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Journal articles on the topic 'Joint task environments'
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1
Dufour, Jonathan S., Alexander M. Aurand, Eric B. Weston, Christopher N. Haritos, Reid A. Souchereau, and William S. Marras. "Dynamic Joint Motions in Occupational Environments as Indicators of Potential Musculoskeletal Injury Risk." Journal of Applied Biomechanics 37, no. 3 (June 1, 2021): 196–203. http://dx.doi.org/10.1123/jab.2020-0213.
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The objective of this study was to test the feasibility of using a pair of wearable inertial measurement unit (IMU) sensors to accurately capture dynamic joint motion data during simulated occupational conditions. Eleven subjects (5 males and 6 females) performed repetitive neck, low-back, and shoulder motions simulating low- and high-difficulty occupational tasks in a laboratory setting. Kinematics for each of the 3 joints were measured via IMU sensors in addition to a “gold standard” passive marker optical motion capture system. The IMU accuracy was benchmarked relative to the optical motion capture system, and IMU sensitivity to low- and high-difficulty tasks was evaluated. The accuracy of the IMU sensors was found to be very good on average, but significant positional drift was observed in some trials. In addition, IMU measurements were shown to be sensitive to differences in task difficulty in all 3 joints (P < .05). These results demonstrate the feasibility for using wearable IMU sensors to capture kinematic exposures as potential indicators of occupational injury risk. Velocities and accelerations demonstrate the most potential for developing risk metrics since they are sensitive to task difficulty and less sensitive to drift than rotational position measurements.
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Xu, Chi, Yunkai Jiang, Jun Zhou, and Yi Liu. "Semi-Supervised Joint Learning for Hand Gesture Recognition from a Single Color Image." Sensors 21, no. 3 (February 2, 2021): 1007. http://dx.doi.org/10.3390/s21031007.
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Hand gesture recognition and hand pose estimation are two closely correlated tasks. In this paper, we propose a deep-learning based approach which jointly learns an intermediate level shared feature for these two tasks, so that the hand gesture recognition task can be benefited from the hand pose estimation task. In the training process, a semi-supervised training scheme is designed to solve the problem of lacking proper annotation. Our approach detects the foreground hand, recognizes the hand gesture, and estimates the corresponding 3D hand pose simultaneously. To evaluate the hand gesture recognition performance of the state-of-the-arts, we propose a challenging hand gesture recognition dataset collected in unconstrained environments. Experimental results show that, the gesture recognition accuracy of ours is significantly boosted by leveraging the knowledge learned from the hand pose estimation task.
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Hughes, L. H., S. Auer, and M. Schmitt. "INVESTIGATION OF JOINT VISIBILITY BETWEEN SAR AND OPTICAL IMAGES OF URBAN ENVIRONMENTS." ISPRS Annals of Photogrammetry, Remote Sensing and Spatial Information Sciences IV-2 (May 28, 2018): 129–36. http://dx.doi.org/10.5194/isprs-annals-iv-2-129-2018.
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In this paper, we present a work-flow to investigate the joint visibility between very-high-resolution SAR and optical images of urban scenes. For this task, we extend the simulation framework SimGeoI to enable a simulation of individual pixels rather than complete images. Using the extended SimGeoI simulator, we carry out a case study using a TerraSAR-X staring spotlight image and a Worldview-2 panchromatic image acquired over the city of Munich, Germany. The results of this study indicate that about 55&thinsp;% of the scene are visible in both images and are thus suitable for matching and data fusion endeavours, while about 25&thinsp;% of the scene are affected by either radar shadow or optical occlusion. Taking the image acquisition parameters into account, our findings can provide support regarding the definition of upper bounds for image fusion tasks, as well as help to improve acquisition planning with respect to different application goals.
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Caruso, Matteo, Paolo Gallina, and Stefano Seriani. "On the Modelling of Tethered Mobile Robots as Redundant Manipulators." Robotics 10, no. 2 (June 12, 2021): 81. http://dx.doi.org/10.3390/robotics10020081.
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Controlling a chain of tethered mobile robots (TMRs) can be a challenging task. This kind of system can be considered kinematically as an open-chain robotic arm where the mobile robots are considered as a revolute joint and the tether is considered as a variable length link, using a prismatic joint. Thus, the TMRs problem is decoupled into two parallel problems: the equivalent robotic manipulator control and the tether shape computation. Kinematic redundancy is exploited in order to coordinate the motion of all mobile robots forming the chain, expressing the constraints acting on the mobile robots as secondary tasks for the equivalent robotic arm. Implementation in the Gazebo simulation environment shows that the methodology is capable of controlling the chain of TMRs in cluttered environments.
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Wang, Cong, Shineng Geng, David T. Branson, Chenghao Yang, Jian S. Dai, and Rongjie Kang. "Task space-based orientability analysis and optimization of a wire-driven continuum robot." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 233, no. 23-24 (November 28, 2019): 7658–68. http://dx.doi.org/10.1177/0954406219889083.
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Compared to traditional rigid robots, continuum robots have intrinsic compliance and therefore behave dexterously when performing tasks in restricted environments. Although there have been many researches on the design and application of continuum robots, a theoretical investigation of their dexterity is still lacking. In this paper, a two-joint wire-driven continuum robot is utilized to demonstrate dexterity by introducing the concept of orientability taking into account two indices, the accessible ratio and angle of the robot, when its tip reaches a certain task space inside the workspace. Based on the kinematic model, the accessible ratio and angle of the continuum robot are calculated using the Monte-Carlo method. From this, the influence of individual joint lengths on the proposed orientability indices and the optimal joint length are then investigated via an improved particle swarm optimization algorithm. Finally, the presented methods were validated through experiments showing that the use of optimal joint length can increase the accessible ratio and reduce the minimum accessible angle by more than 10° in the task space.
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Perreault, Eric J., Kuifu Chen, Randy D. Trumbower, and Gwyn Lewis. "Interactions With Compliant Loads Alter Stretch Reflex Gains But Not Intermuscular Coordination." Journal of Neurophysiology 99, no. 5 (May 2008): 2101–13. http://dx.doi.org/10.1152/jn.01094.2007.
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The human motor system regulates arm mechanics to produce stable postures during interactions with different physical environments. This occurs partly via involuntary mechanisms, including stretch reflexes. Previous single-joint studies demonstrated enhanced reflex sensitivity during interactions with compliant environments, suggesting reflex gain increases to enhance limb stability when that stability is not provided by the environment. This study examined whether similar changes in reflex gain are present throughout the limb following perturbations that simultaneously influence multiple joints. Furthermore, we investigated whether any observed modulation was accompanied by task-specific changes in reflex coordination across muscles, a question that cannot be addressed using single-joint perturbations. Reflexes were elicited during the maintenance of posture by perturbing the arm with a three degrees of freedom robot, configured to have isotropic stiffness of either 10 N/m (compliant) or 10 kN/m (stiff). Perturbation characteristics were matched in both environments. Reflex magnitude was quantified by the average rectified electromyogram, recorded from eight muscles crossing the elbow and shoulder. Reflex coordination was assessed using independent components analysis to compare reflex activation patterns during interactions with stiff and compliant environments. Stretch reflex sensitivity increased significantly in all muscles during interactions with the compliant environment and these changes were not due to changes in background muscle activity. However, there was no significant difference in the reflex coordination patterns observed during interactions with the stiff and compliant environments. These results suggest that reflex modulation occurred through altered use of fixed muscle coordination patterns rather than through a change in reflex coordination.
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Florea, George Albert, and Radu-Casian Mihailescu. "Multimodal Deep Learning for Group Activity Recognition in Smart Office Environments." Future Internet 12, no. 8 (August 9, 2020): 133. http://dx.doi.org/10.3390/fi12080133.
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Deep learning (DL) models have emerged in recent years as the state-of-the-art technique across numerous machine learning application domains. In particular, image processing-related tasks have seen a significant improvement in terms of performance due to increased availability of large datasets and extensive growth of computing power. In this paper we investigate the problem of group activity recognition in office environments using a multimodal deep learning approach, by fusing audio and visual data from video. Group activity recognition is a complex classification task, given that it extends beyond identifying the activities of individuals, by focusing on the combinations of activities and the interactions between them. The proposed fusion network was trained based on the audio–visual stream from the AMI Corpus dataset. The procedure consists of two steps. First, we extract a joint audio–visual feature representation for activity recognition, and second, we account for the temporal dependencies in the video in order to complete the classification task. We provide a comprehensive set of experimental results showing that our proposed multimodal deep network architecture outperforms previous approaches, which have been designed for unimodal analysis, on the aforementioned AMI dataset.
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Caroux, Loïc, Ludovic Le Bigot, and Nicolas Vibert. "Impairment of Shooting Performance by Background Complexity and Motion." Experimental Psychology 62, no. 2 (March 1, 2015): 98–109. http://dx.doi.org/10.1027/1618-3169/a000277.
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In many visual displays such as virtual environments, human tasks involve objects superimposed on both complex and moving backgrounds. However, most studies investigated the influence of background complexity or background motion in isolation. Two experiments were designed to investigate the joint influences of background complexity and lateral motion on a simple shooting task typical of video games. Participants had to perform the task on the moving and static versions of backgrounds of three levels of complexity, while their eye movements were recorded. The backgrounds displayed either an abstract (Experiment 1) or a naturalistic (Experiment 2) virtual environment. The results showed that performance was impaired by background motion in both experiments. The effects of motion and complexity were additive for the abstract background and multiplicative for the naturalistic background. Eye movement recordings showed that performance impairments reflected at least in part the impact of the background visual features on gaze control.
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Abro, Deng, Memon, Laghari, Mohammadani, and Ain. "A Dynamic Application-Partitioning Algorithm with Improved Offloading Mechanism for Fog Cloud Networks." Future Internet 11, no. 7 (June 28, 2019): 141. http://dx.doi.org/10.3390/fi11070141.
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This paper aims to propose a new fog cloud architecture that performs a joint energy-efficient task assignment (JEETA). The proposed JEETA architecture utilizes the dynamic application-partitioning algorithm (DAPTS), a novel algorithm that efficiently decides and switches the task to be offloaded or not in heterogeneous environments with minimal energy consumption. The proposed scheme outperforms baseline approaches such as MAUI, Think Air and Clone Cloud in many performance aspects. Results show that for the execution of 1000 Tasks on fog, mobile offloaded nodes, JEETA consumes the leas, i.e., 23% of the total energy whereas other baseline approaches consume in between 50%–100% of the total energy. Results are validated via real test-bed experiments and trice are driven efficient simulations.
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Kouno, Kentarou, Hiroya Yamada, and Shigeo Hirose. "Development of Active-Joint Active-Wheel High Traversability Snake-Like Robot ACM-R4.2." Journal of Robotics and Mechatronics 25, no. 3 (June 20, 2013): 559–66. http://dx.doi.org/10.20965/jrm.2013.p0559.
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Snake-like hypermobile robots are thought to be effective in search and rescue task applications, and many research institutions have studied such robots. In prior research, we developed an active-joint activewheel snake-like robot, ACM-R4.1, which had a watertight structure and joint torque sensors that also acted as a torque limiter. Although R4.1 was highly robust in severe environments and had high terrain adaptability, we found problems that had to be overcome, such as getting stuck in rough terrain. We therefore propose a more practical snake-like robot, ACMR4.2, in order to maximizemobility performance. The main features of R4.2 are as follows: (1) thin yaw axis joints, (2) light-weight plastic housing made by vacuum injection method, and (3) wheels those were wider than those of R4.1. We tested R4.2 performance and found that it showed higher traversability than R4.1.
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Singla, E., S. Singh, and B. Dasgupta. "Maximizing safety margins in task-based design of redundant manipulators for cluttered environments." Proceedings of the Institution of Mechanical Engineers, Part O: Journal of Risk and Reliability 231, no. 3 (April 5, 2017): 275–85. http://dx.doi.org/10.1177/1748006x17698332.
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Kinematically redundant manipulators help in handling environmental constraints with extra degrees of freedom, but a large number of links may also lead to significant cumulative errors at the distal end, increasing the likelihood of collisions. The focus of this paper is to synthesize a robot with maximized tolerance to avoid potential collisions, while maneuvering in the workspace. A maximized-tolerance-based method in the design stage provides a significant margin to be utilized further during architectural planning and/or in error compensation against any joint clearance error. This is the main contribution of this paper. The strategy is applicable with even a large number of degrees of freedom. A measure, named as RoboGin, is defined both for a single configuration and for a set of configurations. Maximizing this metric over the large solution space of all robotic parameters provides an optimized design from the reliability perspective. The other requirements related to robot’s reachability at the specified task space locations (TSLs), kinematic conditioning and path connectivity are framed as constraints in the formulated optimization problem. The global solutions computed through a simulated annealing technique show significant improvements in overall safety margins even in highly cluttered environments and with a large number of links. Implementation of the proposed strategy is demonstrated through realistic cluttered environments of a power plant, for a leakage testing application.
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Zhao, Liangliang, Zainan Jiang, Yongjun Sun, Jingdong Zhao, and Hong Liu. "Collision-free kinematics for hyper-redundant manipulators in dynamic scenes using optimal velocity obstacles." International Journal of Advanced Robotic Systems 18, no. 1 (January 1, 2021): 172988142199614. http://dx.doi.org/10.1177/1729881421996148.
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Hyper-redundant manipulators have been widely used in the complex and cluttered environment for achieving various kinds of tasks. In this article, we present two contributions. First, we provide a novel algorithm of relating forward and backward reaching inverse kinematic algorithm to velocity obstacles. Our optimization-based algorithm simultaneously handles the task space constraints, the joint limit constraints, and the collision-free constraints for hyper-redundant manipulators based on the generalized framework. Second, we present an extension of our inverse kinematic algorithm to collision avoidance for the hyper-redundant manipulators, where the workspaces may have different types of obstacles. We highlight the performance of our algorithm on hyper-redundant manipulators with various degrees of freedom. The results show that our algorithm has made full use of dexterity of hyper-redundant manipulators in complex environments, enhancing the performance and increasing the flexibility.
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Tuli, Tadele Belay, and Martin Manns. "Real-Time Motion Tracking for Humans and Robots in a Collaborative Assembly Task." Proceedings 42, no. 1 (November 14, 2019): 48. http://dx.doi.org/10.3390/ecsa-6-06636.
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Human-robot collaboration combines the extended capabilities of humans and robots to create a more inclusive and human-centered production system in the future. However, human safety is the primary concern for manufacturing industries. Therefore, real-time motion tracking is necessary to identify if the human worker body parts enter the restricted working space solely dedicated to the robot. Tracking these motions using decentralized and different tracking systems requires a generic model controller and consistent motion exchanging formats. In this work, our task is to investigate a concept for a unified real-time motion tracking for human-robot collaboration. In this regard, a low cost and game-based motion tracking system, e.g., HTC Vive, is utilized to capture human motion by mapping into a digital human model in the Unity3D environment. In this context, the human model is described using a biomechanical model that comprises joint segments defined by position and orientation. Concerning robot motion tracking, a unified robot description format is used to describe the kinematic trees. Finally, a concept of assembly operation that involves snap joining is simulated to analyze the performance of the system in real-time capability. The distribution of joint variables in spatial-space and time-space is analyzed. The results suggest that real-time tracking in human-robot collaborative assembly environments can be considered to maximize the safety of the human worker. However, the accuracy and reliability of the system regarding system disturbances need to be justified.
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DiCesare, Christopher A., Adam W. Kiefer, Scott Bonnette, and Gregory D. Myer. "High-Risk Lower-Extremity Biomechanics Evaluated in Simulated Soccer-Specific Virtual Environments." Journal of Sport Rehabilitation 29, no. 3 (March 1, 2020): 294–300. http://dx.doi.org/10.1123/jsr.2018-0237.
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Context: Laboratory-based biomechanical analyses of sport-relevant movements such as landing and cutting have classically been used to quantify kinematic and kinetic factors in the context of injury risk, which are then used to inform targeted interventions designed to improve risky movement patterns during sport. However, the noncontextual nature of standard assessments presents challenges for assessing sport-relevant skill transfer. Objective: To examine injury-risk biomechanical differences exhibited by athletes during a jump-landing task performed as part of both a standard biomechanical assessment and a simulated, sport-specific virtual reality (VR)-based assessment. Design: Observational study. Setting: Medical center laboratory. Participants: Twenty-two female adolescent soccer athletes (age = 16.0 [1.4] y, height = 165.6 [4.9] cm, and weight = 60.2 [11.4] kg). Interventions: The landing performance was analyzed for a drop vertical jump task and a VR-based, soccer-specific corner-kick scenario in which the athletes were required to jump to head a virtual soccer ball and land. Main Outcome Measures: Hip, knee, and ankle joint kinematic differences in the frontal and sagittal planes. Results: Athletes exhibited reduced hip and ankle flexion, hip abduction, and frontal plane ankle excursion during landing in realistic sport scenario compared with the standard drop vertical jump task. Conclusion: VR-based assessments can provide a sport-specific context in which to assess biomechanical deficits that predispose athletes for lower-extremity injury and offer a promising approach to better evaluate skill transfer to sport that can guide future injury prevention efforts.
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Hornung, Armin, Stefan Oßwald, Daniel Maier, and Maren Bennewitz. "Monte Carlo Localization for Humanoid Robot Navigation in Complex Indoor Environments." International Journal of Humanoid Robotics 11, no. 02 (June 2014): 1441002. http://dx.doi.org/10.1142/s0219843614410023.
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Accurate and reliable localization is a prerequisite for autonomously performing high-level tasks with humanoid robots. In this paper, we present a probabilistic localization method for humanoid robots navigating in arbitrary complex indoor environments using only onboard sensing, which is a challenging task. Inaccurate motion execution of biped robots leads to an uncertain estimate of odometry, and their limited payload constrains perception to observations from lightweight and typically noisy sensors. Additionally, humanoids do not walk on flat ground only and perform a swaying motion while walking, which requires estimating a full 6D torso pose. We apply Monte Carlo localization to globally determine and track a humanoid's 6D pose in a given 3D world model, which may contain multiple levels and staircases. We present an observation model to integrate range measurements from a laser scanner or a depth camera as well as attitude data and information from the joint encoders. To increase the localization accuracy, e.g., while climbing stairs, we propose a further observation model and additionally use monocular vision data in an improved proposal distribution. We demonstrate the effectiveness of our methods in extensive real-world experiments with a Nao humanoid. As the experiments illustrate, the robot is able to globally localize itself and accurately track its 6D pose while walking and climbing stairs.
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Zeng, Jiang, Guang-Zhong Cao, Ye-Ping Peng, and Su-Dan Huang. "A Weld Joint Type Identification Method for Visual Sensor Based on Image Features and SVM." Sensors 20, no. 2 (January 14, 2020): 471. http://dx.doi.org/10.3390/s20020471.
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In the field of welding robotics, visual sensors, which are mainly composed of a camera and a laser, have proven to be promising devices because of their high precision, good stability, and high safety factor. In real welding environments, there are various kinds of weld joints due to the diversity of the workpieces. The location algorithms for different weld joint types are different, and the welding parameters applied in welding are also different. It is very inefficient to manually change the image processing algorithm and welding parameters according to the weld joint type before each welding task. Therefore, it will greatly improve the efficiency and automation of the welding system if a visual sensor can automatically identify the weld joint before welding. However, there are few studies regarding these problems and the accuracy and applicability of existing methods are not strong. Therefore, a weld joint identification method for visual sensor based on image features and support vector machine (SVM) is proposed in this paper. The deformation of laser around a weld joint is taken as recognition information. Two kinds of features are extracted as feature vectors to enrich the identification information. Subsequently, based on the extracted feature vectors, the optimal SVM model for weld joint type identification is established. A comparative study of proposed and conventional strategies for weld joint identification is carried out via a contrast experiment and a robustness testing experiment. The experimental results show that the identification accuracy rate achieves 98.4%. The validity and robustness of the proposed method are verified.
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Zhu, Guoniu, Xiao Xiao, Changsheng Li, Jin Ma, Godwin Ponraj, A. V. Prituja, and Hongliang Ren. "A Bimanual Robotic Teleoperation Architecture with Anthropomorphic Hybrid Grippers for Unstructured Manipulation Tasks." Applied Sciences 10, no. 6 (March 19, 2020): 2086. http://dx.doi.org/10.3390/app10062086.
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Bimanual telemanipulation is vital for facilitating robots to complete complex and dexterous tasks that involve two handheld objects under teleoperation scenarios. However, the bimanual configuration introduces higher complexity, dynamics, and uncertainty, especially in those uncontrolled and unstructured environments, which require more advanced system integration. This paper presents a bimanual robotic teleoperation architecture with modular anthropomorphic hybrid grippers for the purpose of improving the telemanipulation capability under unstructured environments. Generally, there are two teleoperated subsystems within this architecture. The first one is the Leap Motion Controller and the anthropomorphic hybrid robotic grippers. Two 3D printed anthropomorphic hybrid robotic grippers with modular joints and soft layer augmentations are designed, fabricated, and equipped for telemanipulation tasks. A Leap Motion Controller is used to track the motion of two human hands, while each hand is utilized to teleoperate one robotic gripper. The second one is the haptic devices and the robotic arms. Two haptic devices are adopted as the master devices while each of them takes responsibility for one arm control. Based on such a framework, an average RMSE (root-mean-square-error) value of 0.0204 rad is obtained in joint tracking. Nine sign-language demonstrations and twelve object grasping tasks were conducted with the robotic gripper teleoperation. A challenging bimanual manipulation task for an object with 5.2 kg was well addressed using the integrated teleoperation system. Experimental results show that the proposed bimanual teleoperation system can effectively handle typical manipulation tasks, with excellent adaptabilities for a wide range of shapes, sizes, and weights, as well as grasping modes.
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Liang, Jinglun, Yisheng Rong, Guoliang Ye, Xiaoxiao Li, Jianwen Guo, and Zhenzhen He. "Acceleration Level Control of Redundant Manipulators with Physical Constraints Compliance and Disturbance Rejection under Complex Environment." Complexity 2020 (November 7, 2020): 1–14. http://dx.doi.org/10.1155/2020/8844209.
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Investigation of joint torque constraint compliance is of significance for robot manipulators especially working in complex environments. A lot of which is attributed to that, on the one hand, it is beneficial to the improvement of both safety and reliability of the mission execution. On the other hand, the energy consumption required by the robot to complete the desired mission can be reduced. Most existing schemes do not take the joint torque limit and other inherent physical structure limits in a manipulator into account at the same time. In addition, many unavoidable uncertainties such as the external environmental disturbance and/or electromagnetism interferences in the circuit system may influence the accuracy and effectiveness of the task execution for a robot. In this study, we cast light on the acceleration level control of redundant robot manipulators considering both four physical constraint limits and interference rejection. A robust unified quadratic-programming-based hybrid control scheme is proposed, where the joint torque constraints are converted as two inequality constraints based on the robots’ dynamics equation. A recurrent-neural-network-based controller is designed for solving the control variable. Numerical experiments performing in PUMA 560 manipulator and planer manipulator illustrate that a rational torque distribution is obtained among the joints and the considered physical structural vectors are all restricted to the respective constraint range. In addition, even disturbed by the noise, the manipulator still successfully tracks the desired trajectory under the proposed control scheme.
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Ondočko, Štefan, Jozef Svetlík, Michal Šašala, Zdenko Bobovský, Tomáš Stejskal, Jozef Dobránsky, Peter Demeč, and Lukáš Hrivniak. "Inverse Kinematics Data Adaptation to Non-Standard Modular Robotic Arm Consisting of Unique Rotational Modules." Applied Sciences 11, no. 3 (January 28, 2021): 1203. http://dx.doi.org/10.3390/app11031203.
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The paper describes the original robotic arm designed by our team kinematic design consisting of universal rotational modules (URM). The philosophy of modularity plays quite an important role when it comes to this mechanism since the individual modules will be the building blocks of the entire robotic arm. This is a serial kinematic chain with six degrees of freedom of unlimited rotation. It was modeled in three different environments to obtain the necessary visualizations, data, measurements, structural changes measurements and structural changes. In the environment of the CoppeliaSim Edu, it was constructed mainly to obtain the joints coordinates matching the description of a certain spatial trajectory with an option to test the software potential in future inverse task calculations. In Matlab, the model was constructed to check the mathematical equations in the area of kinematics, the model’s simulations of movements, and to test the numerical calculations of the inverse kinematics. Since the equipment at hand is subject to constant development, its model can also be found in SolidWorks. Thus, the model’s existence in those three environments has enabled us to compare the data and check the models’ structural designs. In Matlab and SolidWorks, we worked with the data imported on joints coordinates, necessitating overcoming certain problems related to calculations of the inverse kinematics. The objective was to compare the results, especially in terms of the position kinematics in Matlab and SolidWorks, provided the initial joint coordinate vector was the same.
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Nanayakkara, D. P. Thrishantha, Kazuo Kiguchi, Tsukasa Murakami, Keigo Watanabe, and Kiyotaka Izumi. "Enhancing the Autonomy of Teleoperated Redundant Manipulators Through Fusion of Intelligent Control Modules." Journal of Robotics and Mechatronics 14, no. 3 (June 20, 2002): 278–89. http://dx.doi.org/10.20965/jrm.2002.p0278.
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This paper presents a method for redundancy resolution of an industrial manipulator in a teleoperated force control task. A seven degree-of-freedom (DOF) industrial manipulator manufactured by the Mitsubishi Heavy Industries Ltd. is used for experiments. The task involves obeying a force command sent from a remote computer while autonomously adapting the posture to avoid unexpected obstacles moving toward the manipulator. Redundancy resolution is employed for autonomous adaptation of the configuration to avoid the obstacle while continuing the force control task. This self-adaptive skill on the slave manipulator side is very important because teleoperation is often performed in dangerous or partially unknown environments where unexpected changes such as moving obstacles can well be expected. In such situations, the control ability of the master side is very limited due to the practical limitations of vision sensors to capture a comprehensive view of the environment and the limitations of the degrees of freedom on the master manipulator. The proposed method relies on two modules of an intelligent controller on the slave side. The first is an on-line fuzzy neural network (FNN) for intelligent force control, and the second is a configuration controller that works in harmony with the first to exploit redundancy to react to avoid moving obstacles such that the latter does not inhibit the progress of the former. The second controller generates joint velocity commands in null space of the hand Jacobian, so that its activation does not affect the force controller. Here we show that the proposed method can skillfully avoid a moving obstacle without stopping the force control task. This skillful adaptation ability can significantly improve the efficiency and safety of teleoperated force control tasks with less burden on the master side. This paper presents some promising experimental results to demonstrate the effectiveness of the proposed method.
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Paz, Gabriel Andrade, Marianna de Freitas Maia, Haroldo Gualter Santana, Humberto Miranda, Vicente Lima, and John D. Willson. "Knee Frontal Plane Projection Angle: A Comparison Study Between Drop Vertical Jump and Step-Down Tests With Young Volleyball Athletes." Journal of Sport Rehabilitation 28, no. 2 (February 1, 2019): 153–58. http://dx.doi.org/10.1123/jsr.2017-0204.
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Study Design: Observational study. Context: Altered frontal plane knee mechanics during dynamic tasks have been often associated with lower-extremity injuries. Strategies to decrease these risk factors and improve knee joint stability are often applied in rehabilitation and training environments. Objective: The purpose of this study was to compare knee joint frontal plane projection angles (FPPA) via 2-dimensional video analysis during drop vertical jump (DVJ) and step-down test (SDT) tasks in the preferred and nonpreferred limbs of young male and female volleyball players. Methods: A total of 60 young male (n = 29) and female (n = 31) volleyball players (13.6 [1.1] y, 62.2 [11.2] kg, and 170.8 [10] cm) participated in this study. Once the athletes were screened for inclusion and exclusion criteria, limb preference was operationally defined as the preferred kicking leg or the foot used for stair climbing. In a randomized study design, participants were asked to perform a bilateral DVJ and unilateral step-down landing tasks for both preferred and nonpreferred limb. Kinematic analysis was performed via a 2-dimensional video recording of knee joint FPPA alignment. Results: No difference was noted in FFPA during DVJ and SDT tasks between preferred and nonpreferred limbs in both male and female groups (P > .05). The FFPA was significantly higher for both limbs during DVJ versus SDT in both groups (P ≤ .05), but it was not different between male and female athletes. Conclusions: Based on these findings, clinicians may expect young male and female volleyball athletes to demonstrate similar and symmetrical lower-extremity 2-dimensional knee joint FPPA values across screening tests intended to identify lower-extremity injury risk factors. However, greater FPPA values should be expected during the more dynamic DVJ task.
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Zhao, Weiwei, Hairong Chu, Xikui Miao, Lihong Guo, Honghai Shen, Chenhao Zhu, Feng Zhang, and Dongxin Liang. "Research on the Multiagent Joint Proximal Policy Optimization Algorithm Controlling Cooperative Fixed-Wing UAV Obstacle Avoidance." Sensors 20, no. 16 (August 13, 2020): 4546. http://dx.doi.org/10.3390/s20164546.
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Multiple unmanned aerial vehicle (UAV) collaboration has great potential. To increase the intelligence and environmental adaptability of multi-UAV control, we study the application of deep reinforcement learning algorithms in the field of multi-UAV cooperative control. Aiming at the problem of a non-stationary environment caused by the change of learning agent strategy in reinforcement learning in a multi-agent environment, the paper presents an improved multiagent reinforcement learning algorithm—the multiagent joint proximal policy optimization (MAJPPO) algorithm with the centralized learning and decentralized execution. This algorithm uses the moving window averaging method to make each agent obtain a centralized state value function, so that the agents can achieve better collaboration. The improved algorithm enhances the collaboration and increases the sum of reward values obtained by the multiagent system. To evaluate the performance of the algorithm, we use the MAJPPO algorithm to complete the task of multi-UAV formation and the crossing of multiple-obstacle environments. To simplify the control complexity of the UAV, we use the six-degree of freedom and 12-state equations of the dynamics model of the UAV with an attitude control loop. The experimental results show that the MAJPPO algorithm has better performance and better environmental adaptability.
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Wang, Binrui, Jiqing Huang, Guoyang Shen, and Dijian Chen. "Design of admittance controller with sliding mode based on disturbance observer for elbow joint actuated by pneumatic muscles." Industrial Robot: the international journal of robotics research and application 47, no. 5 (May 20, 2020): 657–67. http://dx.doi.org/10.1108/ir-12-2019-0246.
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Purpose Active compliance control is the key technology for Tri-Co robots (coexisting–cooperative–cognitive robots) to interact with the environment and people. This study aims to make the robot arm shake hands compliantly with people; the paper proposed two closed-loop-compliant control schemes for the dynamic identification of cascade elbow joint. Design/methodology/approach The active compliance control strategy consists of inner and outer loops. The inner loop is the position control using sliding mode control with disturbance observer (SMCDO), in which a new saturation function is designed to replace the traditional signal function of sliding mode control (SMC) law so as to mitigate chatter. The outer loop is the admittance control to regulate the dynamic behaviours of the elbow joint, i.e. its impedance. The simulation is carried out to verify the performance of the proposed control scheme. Findings The results show that the chatter of traditional SMC can be effectively eliminated by using SMCDO with this saturation function. In addition, for the handshake task, the value of threshold force and elbow joint compliance is defined. Then, the threshold force tests, impact tests and elbow-joint compliance tests are carried out. The results show that, in the impedance model, the elbow joint compliance only depends on the stiffness parameters, not on the position control loop. Practical implications The effectiveness of the admittance control based on SMCDO can improve the adaptability of industrial manipulator in different working environments to some degree. Originality/value The admittance control with SMCDO completed trajectory tracking has higher accuracy than that based on SMC.
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Hinshelwood, R. D., and Craig Fees. "Joint responsibility as an attitude of mind (working alongside) a letter by David Wills in the PETT archives." Therapeutic Communities: The International Journal of Therapeutic Communities 36, no. 3 (September 14, 2015): 186–91. http://dx.doi.org/10.1108/tc-01-2014-0001.
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Purpose – The purpose of this paper is to present a previously unpublished letter from children’s therapeutic community pioneer David Wills to his younger colleague in the field, Robert Laslett, which attempts to define and summarise a lifetime’s understanding of the essence of a therapeutic environment. This raises concepts and issues of relevance to current theory and practice in therapeutic environments. Design/methodology/approach – The authors contextualise the 1977 letter from David Wills before presenting it verbatim, with clarifying annotations relating to people and events. They then analyse and discuss the fundamental arguments presented in the letter, with relevance to current thinking and practice. Findings – The approach presented by David Wills to his younger colleague is deeply challenging to current concepts and understandings of therapeutic environments and the role in the therapeutic task of subjectivity and “attitude of mind”. The view is taken that this presents “a great question for wide debate, right now”. Research limitations/implications – Very little historical/analytical research has taken place into the experiences, thinking and practice of those who have built the diverse fields of therapeutic communities and environments, not least because history disturbs and challenges the present. This paper opens a small window on the vast resources which are available, and indicates something of the rich potential for debate and practical challenge Experts by Experience pose to living and, hopefully, learning practitioners to day. Practical implications – Questions are raised: the debate they engender should eventuate into clearer, better grounded, more radical, and more effective practice. Social implications – This letter challenges assumptions about the role and nature of the “therapeutic attitude” and the place of subjectivity, with profound implications for the therapeutic enterprise itself, and the organisation of therapeutic environments, as well as policy, assessment and regulation regimes. Originality/value – The use of previously unpublished archive material opens living questions to examination from a different perspective, widening the debate to include voices of expertise and experience which are generally, consciously or unconsciously, excluded from it. Presenting the letter in its whole, and not excerpted as supporting evidence, allows the voice of expertise by experience to contribute directly to discussion and debate; unbalancing and enriching it.
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de Rugy, Aymar, Mark R. Hinder, Daniel G. Woolley, and Richard G. Carson. "The Synergistic Organization of Muscle Recruitment Constrains Visuomotor Adaptation." Journal of Neurophysiology 101, no. 5 (May 2009): 2263–69. http://dx.doi.org/10.1152/jn.90898.2008.
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Reaching to visual targets engages the nervous system in a series of transformations between sensory information and motor commands. That which remains to be determined is the extent to which the processes that mediate sensorimotor adaptation to novel environments engage neural circuits that represent the required movement in joint-based or muscle-based coordinate systems. We sought to establish the contribution of these alternative representations to the process of visuomotor adaptation. To do so we applied a visuomotor rotation during a center-out isometric torque production task that involved flexion/extension and supination/pronation at the elbow-joint complex. In separate sessions, distinct half-quadrant rotations (i.e., 45°) were applied such that adaptation could be achieved either by only rescaling the individual joint torques (i.e., the visual target and torque target remained in the same quadrant) or by additionally requiring torque reversal at a contributing joint (i.e., the visual target and torque target were in different quadrants). Analysis of the time course of directional errors revealed that the degree of adaptation was lower (by ∼20%) when reversals in the direction of joint torques were required. It has been established previously that in this task space, a transition between supination and pronation requires the engagement of a different set of muscle synergists, whereas in a transition between flexion and extension no such change is required. The additional observation that the initial level of adaptation was lower and the subsequent aftereffects were smaller, for trials that involved a pronation–supination transition than for those that involved a flexion–extension transition, supports the conclusion that the process of adaptation engaged, at least in part, neural circuits that represent the required motor output in a muscle-based coordinate system.
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Jablonski, James A., Brian M. Wade, and Jonathan K. Alt. "Operation assessment: Lessons learned across echelons." Journal of Defense Modeling and Simulation: Applications, Methodology, Technology 16, no. 4 (February 2019): 297–304. http://dx.doi.org/10.1177/1548512919826405.
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Assessors often become invaluable assets to commands, especially during the execution of critical or non-standard missions. Unfortunately, due to the nature of these missions and staff turn-over, assessors often start from ‘scratch’ as young officers in nascent assessment programs. Years of lessons learned are often overlooked. This paper brings together a team of analysts with separate experiences as assessors in Army and Joint assignments from the Combined Joint Task Force (CJTF) level to the Brigade level to share insights gained through experience that apply in nearly all assessment contexts. The authors focus on three primary areas. First, they show how assessors must understand context and should often use reason and qualitative data more than rely on numerical metrics. They then explore how assessors can help staffs and leaders accurately identify trends amidst noisy and chaotic operational environments. Finally, they demonstrate how the assessment team can leverage and assist the staff to enable better assessments.
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Travers, Matthew, Julian Whitman, and Howie Choset. "Shape-based coordination in locomotion control." International Journal of Robotics Research 37, no. 10 (March 24, 2018): 1253–68. http://dx.doi.org/10.1177/0278364918761569.
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Highly articulated systems are capable of executing a variety of behaviors by coordinating their many internal degrees of freedom to help them move more effectively in complex terrains. However, this inherent variety poses significant challenges that have been the subject of a great deal of previous work: What are the most effective or most efficient methods for achieving the intrinsic coordination necessary to produce desired global objectives? This work takes these questions one step further, asking how different levels of coordination, which we quantify in terms of kinematic coupling, affect articulated locomotion in environments with different degrees of underlying structure. We introduce shape functions as the analytical basis for specifying kinematic coupling relationships that constrain the relative motion among the internal degrees of freedom for a given system during its nominal locomotion. Furthermore, we show how shape functions are used to derive shape-based controllers (SBCs) that manage the compliant interaction between articulated bodies and the environment while explicitly preserving the inter-joint coupling defined by shape functions. Initial experimental evidence provides a comparison of the benefits of different levels of coordination for two separate platforms in environments with different degrees of inherent structure. The experimental results show that decentralized implementations, where there is relatively little inter-joint coupling, perform well across a spectrum of different terrains but that there are potential benefits to higher degrees of coupling in structured terrains. We discuss how this observation has implications related to future planning and control approaches that actively “tune” their underlying structure by dynamically varying the assumed level of coupling as a function of task specification and local environmental conditions.
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MOOSAVIAN, S. ALI A., MANSOOR ALGHOONEH, and AMIR TAKHMAR. "CARTESIAN APPROACH FOR GAIT PLANNING AND CONTROL OF BIPED ROBOTS ON IRREGULAR SURFACES." International Journal of Humanoid Robotics 06, no. 04 (December 2009): 675–97. http://dx.doi.org/10.1142/s0219843609001942.
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Biped robots possess higher capabilities than other mobile robots for moving on uneven environments. However, due to natural postural instability of these robots, their motion planning and control become a more important and challenging task. This article presents a Cartesian approach for gait planning and control of biped robots without the need to use the inverse kinematics and the joint space trajectories, thus the proposed approach could substantially reduce the processing time in both simulation studies and online implementations. It is based on constraining four main points of the robot in Cartesian space. This approach exploits the concept of Transpose Jacobian control as a virtual spring and damper between each of these points and the corresponding desired trajectory, which leads to overcome the redundancy problem. These four points include the tip of right and left foot, the hip joint, and the total center of mass (CM). Furthermore, in controlling biped robots based on desired trajectories in the task space, the system may track the desired trajectory while the knee is broken. This problem is solved here using a PD controller which will be called the Knee Stopper. Similarly, another PD controller is proposed as the Trunk Stopper to limit the trunk motion. Obtained simulation results show that the proposed Cartesian approach can be successfully used in tracking desired trajectories on various surfaces with lower computational effort.
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McGhee, Scott, Sivrama Nalluri, Ron Reeve, Robert Rongo, Fritz Prinz, and Jim Hemmerle. "Automatic Programming System for Shipyard Robots." Journal of Ship Production 13, no. 02 (May 1, 1997): 93–100. http://dx.doi.org/10.5957/jsp.1997.13.2.93.
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The application of robots to variable tasks in unstructured environments presents a series of problems that must be solved in order to achieve viable results Common teaching-type robots cannot be applied in these cases as the programming time and labor investment far exceed the time and cost of direct manual production. Numerically controlled (NC) robots programmed off-line by modified NC methods have been applied with economic success to program robots directly from computer-aided design (CAD) data where tasks are sufficiently repetitive and the operating environment is sufficiently structured Similarly, off-line programming systems have been developed by various robot manufacturers to generate instructions from CAD data for their robots. Likewise, developers of 3D simulation software have devised methods to merge CAD data with physical models of robots and system hardware to produce robot path programs that approximate the tasks to be performed. Each of these systems is unable to provide a totally automated means to program robot tasks directly from CAD data due to inaccuracies in the real-world elements and/or the models, and due to a lack of knowledge about the processes. A new approach to automatic robot programming is needed that is capable of dealing with:inherent differences between the CAD models and the real-world parts;uncertainties regarding the precise location and accessibility of the parts relative to the robot:process knowledge required to adapt these differences and uncertainties; andprocess knowledge essential to optimizing robot activities. Such an automatic robot programming system is being developed to meet the dual-use defense and commercial ship construction needs of American shipyards under the Technology Reinvestment Project (TRP) for Shipbuilding Robotics. This system automates the programmer's task of identifying location of welds, assigning weld process parameters and adaptive welding strategies to each joint. A procedural diagram for this system is shown in Figure 1. The results and benefits of this approach are described herein. Fig. 1Procedure for automatic off-line robot task planning
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Basso, Marcos Aurélio, and Daniel Rodrigues dos Santos. "A JOINT EFFORT OF SPEEDED-UP ROBUST FEATURES ALGORITHM AND A DISPARITY-BASED MODEL FOR 3D INDOOR MAPPING USING RGB-D DATA." Boletim de Ciências Geodésicas 24, no. 3 (August 2018): 351–66. http://dx.doi.org/10.1590/s1982-21702018000300023.
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Abstract In this paper, we present a method for 3D mapping of indoor environments using RGB-D data. The contribution of our proposed method is two-fold. First, our method exploits a joint effort of the speed-up robust features (SURF) algorithm and a disparity-to-plane model for a coarse-to-fine registration procedure. Once the coarse-to-fine registration task accumulates errors, the same features can appear in two different locations of the map. This is known as the loop closure problem. Then, the variance-covariance matrix that describes the uncertainty of transformation parameters (3D rotation and 3D translation) for view-based loop closure detection followed by a graph-based optimization are proposed to achieve a 3D consistent indoor map. To demonstrate and evaluate the effectiveness of the proposed method, experimental datasets obtained in three indoor environments with different levels of details are used. The experimental results shown that the proposed framework can create 3D indoor maps with an error of 11,97 cm into object space that corresponds to a positional imprecision around 1,5% at the distance of 9 m travelled by sensor.
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H. Godiwalla, Yezdi. "Global Organizational Innovation Strategy." International Journal of Social Science Studies 6, no. 8 (July 24, 2018): 45. http://dx.doi.org/10.11114/ijsss.v6i8.3477.
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Global innovation strategy makes a global (or international) organization more competitive and contributes to long term growth. A focus on newer trends and approaches in the technology and internal and external organizational processes would help the innovative and entrepreneurial spirit and endeavor. The proper organizational entrepreneurial goals, strategy and culture would generate greater connectedness with the relevant task environments for the global organization to explore and subsequently pursue newer product and services. Altogether, the integrated global sharing, joint experimentation among its subsidiaries and their combined innovation effort, the well-interfaced global supply chain’s innovative endeavors, and the well-planned and systematic innovation strategy, together would spur greater global competitiveness and growth. It is a combined global approach that would effectively generate innovation.
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Park, Tae-Yong, Jang-Joon Lee, Jung-Hoon Kim, and Hyun-Ung Oh. "Preliminary Thermal Design and Analysis of Lunar Lander for Night Survival." International Journal of Aerospace Engineering 2018 (October 30, 2018): 1–13. http://dx.doi.org/10.1155/2018/4236396.
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A lunar lander is exposed to extreme lunar thermal environments with a nighttime of 14.75 earth days. Thus, a proper thermal design is an important task to guarantee a successful lunar mission. This paper describes a preliminary thermal design and analysis results of a lunar lander to ensure its survivability during lunar night. The effectiveness of the thermal designs of a lunar lander with various thermal hardwares was numerically investigated according to the landing candidate areas to determine which design is the most feasible for night survival. In addition, we analyzed the mechanical safety of the solder joint of electronic components in accordance with the operating temperature range, because it is an important factor for reducing the system power budget during night survival.
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Schiller, Mark. "Nato Multinational Brigade Interoperability: Issues, Mitigating Solutions and is it Time for a Nato Multinational Brigade Doctrine?" Journal on Baltic Security 2, no. 1 (June 1, 2016): 102–16. http://dx.doi.org/10.1515/jobs-2016-0032.
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Abstract Multinational Brigade Operations involving NATO and its European Partners are the norm in the post-Cold War Era. Commonplace today are Multinational Brigades, composed of staffs and subordinate units representing almost every NATO Country and Partner, participating in training exercises or actual operations in both the European and Southwest Asian Theatres. Leadership challenges are prevalent for the Multinational Brigade Commander and his staff, especially those challenges they face in achieving an effective level of brigade interoperability in order to conduct successful operations in NATO’s present and future operating environments. The purpose of this paper is twofold: to examine the major interoperability obstacles a multinational brigade commander and his staff are likely to encounter during the planning and execution of brigade operations; and, to recommend actions and measures a multinational brigade commander and his staff can implement to facilitate interoperability in a multinational brigade operating environment. Several key interoperability topics considered integral to effective multinational brigade operations will be examined and analysed to include understanding partner unit capabilities and limitations facilitated by an integration plan, appropriate command and support relationships, compatible communications, synchronized intelligence and information collection, establishing effective liaison, and fratricide prevention. The paper conclusion will urge for a NATO land brigade doctrine considering doctrine’s critical importance to effective brigade command and control interoperability and the expected missions a land brigade will encounter in future NATO operating environments as part of the NATO Very High Readiness Joint Task Force (VJTF).
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Dideriksen, Jakob L., Francesco Negro, and Dario Farina. "The optimal neural strategy for a stable motor task requires a compromise between level of muscle cocontraction and synaptic gain of afferent feedback." Journal of Neurophysiology 114, no. 3 (September 2015): 1895–911. http://dx.doi.org/10.1152/jn.00247.2015.
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Increasing joint stiffness by cocontraction of antagonist muscles and compensatory reflexes are neural strategies to minimize the impact of unexpected perturbations on movement. Combining these strategies, however, may compromise steadiness, as elements of the afferent input to motor pools innervating antagonist muscles are inherently negatively correlated. Consequently, a high afferent gain and active contractions of both muscles may imply negatively correlated neural drives to the muscles and thus an unstable limb position. This hypothesis was systematically explored with a novel computational model of the peripheral nervous system and the mechanics of one limb. Two populations of motor neurons received synaptic input from descending drive, spinal interneurons, and afferent feedback. Muscle force, simulated based on motor unit activity, determined limb movement that gave rise to afferent feedback from muscle spindles and Golgi tendon organs. The results indicated that optimal steadiness was achieved with low synaptic gain of the afferent feedback. High afferent gains during cocontraction implied increased levels of common drive in the motor neuron outputs, which were negatively correlated across the two populations, constraining instability of the limb. Increasing the force acting on the joint and the afferent gain both effectively minimized the impact of an external perturbation, and suboptimal adjustment of the afferent gain could be compensated by muscle cocontraction. These observations show that selection of the strategy for a given contraction implies a compromise between steadiness and effectiveness of compensations to perturbations. This indicates that a task-dependent selection of neural strategy for steadiness is necessary when acting in different environments.
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Caliskan, Pinar Melodi, Anne Benjaminse, and Alli Gokeler. "Development of an on-field injury screening test using wearable sensor technology." Orthopaedic Journal of Sports Medicine 8, no. 9_suppl7 (September 1, 2020): 2325967120S0051. http://dx.doi.org/10.1177/2325967120s00513.
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Introduction: Injuries of the anterior cruciate ligament (ACL) commonly occur during complex game situations when the athlete encounters multiple factors such as ball, opponent, field position, and game strategy (Grooms et al., 2018). Many of the current traditional injury screening programs are performed within a predictable, fixed or ‘closed’ environment which do not represent real game situations that require high neurocognitive demands (Dingenen & Gokeler, 2017; Grooms et al., 2018). A complementary approach to lab-based settings is necessary to incorporate the demands of the complex athletic environments. By using wearable sensor technology, we aim to develop an on-field injury screening test in elite youth male soccer players. Investigating the individual differences in motor coordination patterns of the players during sport-specific tasks might enhance our understanding of how ACL injuries occur. Hypotheses: We hypothesized that the motor coordination patterns of the players would be affected when they perform under different conditions manipulated with constraints (task and environmental). Methods: A football-specific test setup was created to analyse the kinematic and performance measures of a group of 17 male youth elite football players aged 15 years (height = 164 ± 9 cm, mass = 50.9± 7.4 kg). The players were grouped into two and measured on two consecutive days. All the players were instructed to complete the test setup (4 conditions, 5 trials) as fast as possible. Condition 1 includes no constraint, condition 2 includes a task constraint (football dummies), condition 3 includes an environmental constraint (stroboscopic glasses) (SENAPTEC, Beaverton, Oregon) and condition 4 includes both task and environmental constraints. 3-D kinematics of the hip, knee, ankle joints were captured using Xsens wearable full-body sensor suits (Xsens, MVN Link version, Enschede, The Netherlands). MATLAB (MATLAB R2019a, The MathWorks Inc., Massachusetts) was used to process and analyse the kinematic data. Data from condition 1 was determined as reference behavior/condition to be compared to other conditions. Kinematic data are presented in attitude vectors (ATV). Results: In total, 81% of the players demonstrated a significant difference (P < 0.05) in angles of hip, knee and ankle joints when performing under different conditions. The percentage of players with increased comparison-based joint movements as follows; condition 1 to condition 2 comparison; 41% hip flexion, 59% hip extension, 53% hip abduction, 47% hip adduction, 62% knee flexion, 38% knee extension, 59% knee abduction, 41% knee adduction, 47% ankle dorsiflexion, 53% ankle plantarflexion, condition 1 to condition 3 comparison; 35% hip flexion, 65% hip extension, 47% hip abduction, 53% hip adduction, 50% knee flexion, 50% knee extension, 41% knee abduction, 59% knee adduction, 59% ankle dorsiflexion, 41% ankle plantarflexion and condition 1 to condition 4 comparison; 31% hip flexion, 69% hip extension, 38% hip abduction, 62% hip adduction, 60% knee flexion, 40% knee extension, 44% knee abduction, 56% knee adduction, 69% ankle dorsiflexion, 31% ankle plantarflexion. Conclusion: The result of this pilot study demonstrated that manipulating task with different constraints caused significant changes in players’ motor coordination patterns which supported the hypothesis of our study. Our findings suggest to develop ACL injury screening tests in a sport-specific setting.
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de La Ville, Valérie-Inés, and Nathalie Nicol. "Shopping from a child’s perspective: an anxiety-generating experience?" International Journal of Retail & Distribution Management 47, no. 6 (June 10, 2019): 680–98. http://dx.doi.org/10.1108/ijrdm-09-2017-0210.
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Purpose The purpose of this paper is to offer some insight into how siblings aged between 4 and 12, engaged in a collaborative drawing activity at home, recall the shopping trips they have experienced. Design/methodology/approach Using a Vygotskian perspective, the data collection consisted of engaging 15 pairs of siblings in the production of a joint drawing of a shop of their choice. Drawing in pairs opens a Zone of Proximal Development (Vygotsky, 1978) where the younger child benefits from verbal guidance by the older one to achieve the common task. This situation enables the researcher to gain close access to children’s knowledge about stores and to the words they use to describe their personal shopping experiences. Findings This exploratory research reveals some constitutive elements of children’s “shopscapes” (Nicol, 2014), i.e. the imaginary geographies they actively elaborate through their daily practices and experiences with regard to retail environments. In their communicative interactions when elaborating a joint drawing of the shop they have chosen, children demonstrate that they master a considerable body of knowledge about retail environments. Surprisingly, recalling their shopping practices sheds light on various anxiety-generating dimensions. Research limitations/implications The data collection is based on a remembering exercise performed at home and does not bring information about what children actually do in retail environments. Moreover, the children were asked to focus on buying a present for a friend’s birthday, therefore the information gathered essentially relates to toy stores. Practical implications This research underlines the necessity for retailers to endeavour to reduce some of the anxious feelings depicted and verbalized by children, by improving the welcome for children into their stores. Social implications There are also opportunities for retailers to invest in the consumption education area by guiding young visitors so that they learn how to behave as apprentice consumers in retail outlets. Originality/value The child-centric perspective of the study reveals new and surprising insights about the way children report their memorised shopping experiences.
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Wang, Wenbo, Houguang Liu, Jianhua Yang, Guohua Cao, and Chunli Hua. "Speech enhancement based on noise classification and deep neural network." Modern Physics Letters B 33, no. 17 (June 18, 2019): 1950188. http://dx.doi.org/10.1142/s0217984919501884.
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Deep neural network (DNN) has recently been successfully adopted as a regression model in speech enhancement. Nonetheless, training machines to adapt different noise is a challenging task. Because every noise has its own characteristics which can be combined with speech utterance to give huge variation on which the model has to operate on. Thus, a joint framework combining noise classification (NC) and speech enhancement using DNN was proposed. We first determined the noise type of contaminated speech by the voice activity detection (VAD)-DNN and the NC-DNN. Then based on the noise classification results, the corresponding SE-DNN model was applied to enhance the contaminated speech. In addition, in order to make method simpler, the structure of different DNNs was similar and the features were the same. Experimental results show that the proposed method effectively improved the performance of speech enhancement in complex noise environments. Besides, the accuracy of classification had a great influence on speech enhancement.
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Andersh, Jonathan, and Bérénice Mettler. "Modeling the Human Visuo-Motor System to Support Remote-Control Operation." Sensors 18, no. 9 (September 6, 2018): 2979. http://dx.doi.org/10.3390/s18092979.
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The working hypothesis in this project is that gaze interactions play a central role in structuring the joint control and guidance strategy of the human operator performing spatial tasks. Perceptual guidance and control is the idea that the visual and motor systems form a unified perceptuo-motor system where necessary information is naturally extracted by the visual system. As a consequence, the response of this system is constrained by the visual and motor mechanisms and these effects should manifest in the behavioral data. Modeling the perceptual processes of the human operator provides the foundation necessary for a systems-based approach to the design of control and display systems used by remotely operated vehicles. This paper investigates this hypothesis using flight tasks conducted with remotely controlled miniature rotorcraft, taking place in indoor settings that provide rich environments to investigate the key processes supporting spatial interactions. This work also applies to spatial control tasks in a range of application domains that include tele-operation, gaming, and virtual reality. The human-in-the-loop system combines the dynamics of the vehicle, environment, and human perception–action with the response of the overall system emerging from the interplay of perception and action. The main questions to be answered in this work are as follows: (i) what is the general control and guidance strategy of the human operator, and (ii) how is information about the vehicle and environment extracted visually by the operator. The general approach uses gaze as the primary sensory mechanism by decoding the gaze patterns of the pilot to provide information for estimation, control, and guidance. This work differs from existing research by taking what have largely been conceptual ideas on action–perception and structuring them to be implemented for a real-world problem. The paper proposes a system model that captures the human pilot’s perception–action loop; the loop that delineates the main components of the pilot’s perceptuo-motor system, including estimation of the vehicle state and task elements based on operator gaze patterns, trajectory planning, and tracking control. The identified human visuo-motor model is then exploited to demonstrate how the perceptual and control functions system can be augmented to reduce the operator workload.
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Zirk, Anna, Rebecca Wiczorek, and Dietrich Manzey. "Do We Really Need More Stages? Comparing the Effects of Likelihood Alarm Systems and Binary Alarm Systems." Human Factors: The Journal of the Human Factors and Ergonomics Society 62, no. 4 (June 19, 2019): 540–52. http://dx.doi.org/10.1177/0018720819852023.
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Objective This research investigates the potential behavioral and performance benefits of a four-stage likelihood alarm system (4-LAS) contrasting a 3-LAS, a binary alarm system with a liberal threshold (lib-BAS), and a BAS with a conservative threshold (con-BAS). Background Prior research has shown performance benefits of 3-LASs over conventional lib-BASs due to more distinct response strategies and better discriminating true from false alerts. This effect might be further enhanced using 4-LASs. However, the increase in stages could cause users to reduce cognitive complexity by responding in the same way to the two lower and the two higher stages, thus treating the 4-LAS like a con-BAS. Method All systems were compared using a dual-task paradigm. Response strategies, number of joint human machine (JHM) false alarms (FAs), misses, and sensitivity were regarded. Results Compared with the lib-BAS, JHM sensitivity only improved with the 4-LAS and the con-BAS. However, the number of JHM misses was lowest for the con-BAS compared with all other systems. Conclusion JHM sensitivity improvements can be achieved by using a 4-LAS, as well as a con-BAS. However, only the latter one may also reduce the number of JHM misses, which is remarkable considering that BASs with conservative thresholds a priori commit more inbuilt misses than other systems. Application Results suggest implementing conservative BASs in multi-task working environments to improve JHM sensitivity and reduce the number of JHM misses. When refraining from designing systems which are miss prone, 4-LASs represent a suitable compromise.
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Kundu, Jogendra Nath, Siddharth Seth, Rahul M V, Mugalodi Rakesh, Venkatesh Babu Radhakrishnan, and Anirban Chakraborty. "Kinematic-Structure-Preserved Representation for Unsupervised 3D Human Pose Estimation." Proceedings of the AAAI Conference on Artificial Intelligence 34, no. 07 (April 3, 2020): 11312–19. http://dx.doi.org/10.1609/aaai.v34i07.6792.
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Estimation of 3D human pose from monocular image has gained considerable attention, as a key step to several human-centric applications. However, generalizability of human pose estimation models developed using supervision on large-scale in-studio datasets remains questionable, as these models often perform unsatisfactorily on unseen in-the-wild environments. Though weakly-supervised models have been proposed to address this shortcoming, performance of such models relies on availability of paired supervision on some related task, such as 2D pose or multi-view image pairs. In contrast, we propose a novel kinematic-structure-preserved unsupervised 3D pose estimation framework, which is not restrained by any paired or unpaired weak supervisions. Our pose estimation framework relies on a minimal set of prior knowledge that defines the underlying kinematic 3D structure, such as skeletal joint connectivity information with bone-length ratios in a fixed canonical scale. The proposed model employs three consecutive differentiable transformations namely forward-kinematics, camera-projection and spatial-map transformation. This design not only acts as a suitable bottleneck stimulating effective pose disentanglement, but also yields interpretable latent pose representations avoiding training of an explicit latent embedding to pose mapper. Furthermore, devoid of unstable adversarial setup, we re-utilize the decoder to formalize an energy-based loss, which enables us to learn from in-the-wild videos, beyond laboratory settings. Comprehensive experiments demonstrate our state-of-the-art unsupervised and weakly-supervised pose estimation performance on both Human3.6M and MPI-INF-3DHP datasets. Qualitative results on unseen environments further establish our superior generalization ability.
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Niu, Guochen, Yunxiao Zhang, and Wenshuai Li. "Path Planning of Continuum Robot Based on Path Fitting." Journal of Control Science and Engineering 2020 (December 22, 2020): 1–11. http://dx.doi.org/10.1155/2020/8826749.
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The Continuum Robot has a multiredundant dof structure, which is extremely advantageous in the unstructured environment, and can complete such tasks as aircraft fuel tank inspection. However, due to its complex kinematics and coupling of joint motion, its motion path planning is also a challenging task. In this paper, a path planning method for Continuum Robot based on an equal curvature model in an aircraft fuel tank environment is proposed. Considering the complexity of calculation and the structural characteristics of Continuum Robot, a feasible obstacle avoidance discrete path is obtained by using the improved RRT algorithm. Then, joint fitting is performed on the existing discrete path according to the kinematic model of Continuum Robot, joint obstacle avoidance was conducted in the process of fitting, and finally, a motion path suitable for the Continuum Robot was selected. A reasonable experiment is designed based on MATLAB, and simulation and analysis results demonstrate excellent performance of this method and feasibility of path planning.
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Godiwalla, Yezdi H. "Strategic Management for Global Firms: A Conceptual Discussion." International Journal of Social Science Studies 6, no. 11 (October 18, 2018): 40. http://dx.doi.org/10.11114/ijsss.v6i11.3695.
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Global organizations have to proceed with a global and strategic perspective in order to be effective. This is in contrast to domestically or regionally focused organizations. Global organizations would benefit from simultaneously pursuing: (a) led by headquarters (HQ) selectively-fostered integrative, global and strategic approaches, and, (b) decentralized foreign subsidiary tactical and operational initiatives. The simultaneous pursuits of the two divergent approaches require capable management teams at both levels: (a) the global HQ, as well as, (b) the foreign subsidiary units. The unique task environments of each foreign subsidiary make it compelling for the HQ to delegate the operational decision making to the foreign subsidiary. For the combined and well-coordinated global vision, choices, goals and strategy, the HQ must take the strategic leadership role.The partnership and collaborative efforts among the HQ and foreign subsidiaries’ executives will foster a together-ness feeling and better ownership of the responsibility among the foreign subsidiaries’ executives. The hierarchical, top-down approach would then be replaced by a joint, information-sharing approach that would engender an era of trust and mutual respect. There would be closer to power equality rather than disproportionate distribution of power. Power would then be posited to where most information and direct skills reside.
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Madinei, Saman, Sunwook Kim, Mohammad Mehdi Alemi, Divya Srinivasan, and Maury A. Nussbaum. "Assessment of Two Passive Back-Support Exoskeletons in a Simulated Precision Manual Assembly Task." Proceedings of the Human Factors and Ergonomics Society Annual Meeting 63, no. 1 (November 2019): 1078–79. http://dx.doi.org/10.1177/1071181319631192.
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Low back pain (LBP) remains the most prevalent and costly work-related disability in the United States, accounting for ~40% of annual musculoskeletal disorders (BLS, 2018) and imposing an economic burden of over $50 billion (Davis, 2012). Many intervention approaches have been explored to reduce the physical requirements of occupational tasks. Examples include training in work methods, modifying work stations, re-organizing work processes, and using mechanical aids such as cranes and power-lift tables (Chaffin et al., 1999; Lavender et al., 2013; Madinei et al., 2018). While these approaches can be effective, they can also be excessively costly or even infeasible for certain work environments (Graham et al., 2009). Industrial back-support exoskeletons (BSEs) – designed to augment the back and hip muscles – have been introduced as an alternative intervention to reduce the physical demands on the back muscles and consequently mitigate the risk of LBP (De Looze et al., 2016). However, there is limited evidence regarding the efficacy of BSEs in work scenarios that require sustained and/or non-neutral trunk bending (such as manual assembly), which are well-known LBP risk factors (e.g., Norman et al., 1998; Fathallah et al., 2008). The efficacy of two passive BSE designs (i.e., BackX™ and Laevo™) was examined by quantifying trunk extensor muscle activity during a lab-based simulation of a precision manual assembly task. Both devices incorporate a passive torque generation mechanism about the hip joint that is intended to augment the torso extensor muscles. Yet, the devices differ in specific design characteristics, such as major body anchor points for the torque generation mechanism (upper back, waist, and thigh [BackX™ AC] vs. chest, waist, and thigh [Laevo™]). Eighteen (gender-balanced) participants, with no recent musculoskeletal injuries or disorders, completed a simulated assembly task using a “grooved pegboard” (Lafayette Instruments, IN, USA) in 20 different pegboard locations. These locations were defined by four different heights (waist, knee, ankle, and below floor levels), three horizontal distances (0, 20, and 40 cm away from the feet), and three orientation angles (0°, 45°, and 90° to the right of the mid-sagittal plane). For a given pegboard location condition, participants were asked to complete the assembly task “as quickly as possible”. Muscle activity was monitored bilaterally from two trunk extensors (i.e., iliocostalis lumborum [ILL] and thoracic erector spinae [TES]) using a telemetered surface electromyography (EMG) system (TeleMyo Desktop DTS, Noraxon, AZ, USA). Note that before performing the assembly task in any of the pegboard location conditions, participants completed trials of maximum isometric voluntary contractions for those muscle groups for normalizing EMG. Outcome measures were the median level of left-side back muscle activity (LBM = mean of 50th percentile normalized EMGs [nEMGs] of left TES and ILL) and the median level of right-side back muscle activity (RBM). Overall, BackX™ use (vs. Laevo™) led to a larger reduction in median levels of back muscle activity levels (≤ 37.9% vs. ≤ 23.9% reduction), and a significant reduction in activity was observed in a larger set of conditions (15 vs. 7 conditions). Additionally, the largest reductions when using BackX™ were found at the ankle level (≤ 38% vs. no reductions for Laevo™), followed by knee level (≤ 32% vs. ≤ 24% for Laevo™), waist level (≤ 30% vs. ≤ 14% for Laevo™), and below floor level (≤ 29% vs. ≤ 10% for Laevo™). Our findings suggest that the beneficial effects of a BSE can be task-specific and that such effects may also be specific to BSE design approaches. Notably, the effects of BSE use found here can be considered practically meaningful. For context, the magnitude of median levels of bilateral low-back muscle activities ranged from ~4-18% nEMG, and using a BSE yielded reductions up to ~5% nEMG, depending upon the specific BSE and task condition. More research is warranted, though, to characterize the task specificity and generalizability of different BSE design approaches in terms of physical demands and task performance.
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Douville, Brett, Libby Levison, and Norman I. Badler. "Task-Level Object Grasping for Simulated Agents." Presence: Teleoperators and Virtual Environments 5, no. 4 (January 1996): 416–30. http://dx.doi.org/10.1162/pres.1996.5.4.416.
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Simulating a human figure performing a manual task requires that the agent interact with objects in the environment in a realistic manner. Graphic or programming interfaces to control human figure animation, however, do not allow the animator to instruct the system with concise “high-level” commands. Instructions coming from a high-level planner cannot be directly given to a synthetic agent because they do not specify such details as which end-effector to use or where on the object to grasp. Because current animation systems require joint angle displacement descriptions of motion—even for motions that incorporate upwards of 15 joints—an efficient connection between high-level specifications and low-level hand joint motion is required. In this paper we describe a system that directs task-level, general-purpose, object grasping for a simulated human agent. The Object-Specific Reasoner (OSR) is a reasoning module that uses knowledge of the object of the underspecified action to generate values for missing parameters. The Grasp Behavior manages simultaneous motions of the joints in the hand, wrist, and arm, and provides a programmer with a high-level description of the desired action. When composed hierarchically, the OSR and the Grasp behavior interpret task-level commands and direct specific motions to the animation system. These modules are implemented as part of the Jock system at the University of Pennsylvania.
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Haaken, Klaus, Gian Piero Deidda, Giorgio Cassiani, Rita Deiana, Mario Putti, Claudio Paniconi, Carlotta Scudeler, and Andreas Kemna. "Flow dynamics in hyper-saline aquifers: hydro-geophysical monitoring and modeling." Hydrology and Earth System Sciences 21, no. 3 (March 9, 2017): 1439–54. http://dx.doi.org/10.5194/hess-21-1439-2017.
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Abstract. Saline–freshwater interaction in porous media is a phenomenon of practical interest particularly for the management of water resources in arid and semi-arid environments, where precious freshwater resources are threatened by seawater intrusion and where storage of freshwater in saline aquifers can be a viable option. Saline–freshwater interactions are controlled by physico-chemical processes that need to be accurately modeled. This in turn requires monitoring of these systems, a non-trivial task for which spatially extensive, high-resolution non-invasive techniques can provide key information. In this paper we present the field monitoring and numerical modeling components of an approach aimed at understanding complex saline–freshwater systems. The approach is applied to a freshwater injection experiment carried out in a hyper-saline aquifer near Cagliari (Sardinia, Italy). The experiment was monitored using time-lapse cross-hole electrical resistivity tomography (ERT). To investigate the flow dynamics, coupled numerical flow and transport modeling of the experiment was carried out using an advanced three-dimensional (3-D) density-driven flow-transport simulator. The simulation results were used to produce synthetic ERT inversion results to be compared against real field ERT results. This exercise demonstrates that the evolution of the freshwater bulb is strongly influenced by the system's (even mild) hydraulic heterogeneities. The example also highlights how the joint use of ERT imaging and gravity-dependent flow and transport modeling give fundamental information for this type of study.
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Tang, Jianzhong, Yougong Zhang, Fanghao Huang, Jianpeng Li, Zheng Chen, Wei Song, Shiqiang Zhu, and Jason Gu. "Design and Kinematic Control of the Cable-Driven Hyper-Redundant Manipulator for Potential Underwater Applications." Applied Sciences 9, no. 6 (March 18, 2019): 1142. http://dx.doi.org/10.3390/app9061142.
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Underwater manipulators are important robotic tools in the exploration of the ocean environment. Up to now, most existing underwater manipulators are rigid and with fixed 5 or 7 degrees of freedom (DOF), which may not be very suitable for some complicated underwater scenarios (e.g., pipe networks, narrow deep cavities, etc.). The biomimetic concept of muscles and tendons is also considered as continuum manipulators, but load capacity and operation accuracy are their essential drawbacks and thus limit their practical applications. Recently, the cable-driven technique has been developed for manipulators, which can include numerous joints and hyper-redundant DOF to execute tasks with dexterity and adaptability and thus they have strong potential for these complex underwater applications. In this paper, the design of a novel cable-driven hyper-redundant manipulator (CDHRM) is introduced, which is driven by multiple cables passing through the tubular structure from the base to the end-effector, and the joint numbers can be extended and decided by the specific underwater task requirements. The kinematic analysis of the proposed CDHRM is given which includes two parts: the cable-joint kinematics and the joint-end kinematics. The geometric relationship between the cable length and the joint angles are derived via the established geometric model for the cable-joint kinematics, and the projection relationship between the joint angles and end-effector’s pose is established via the spatial coordinate transformation matrix for the joint-end kinematics. Thus, the complex mapping relationships among the cables, joints and end-effectors are clearly achieved. To implement precise control, the kinematic control scheme is developed for the CDHRM with series-parallel connections and hyper-redundancy to achieve good tracking performance. The experiment on a real CDHRM system with five joints is carried out and the results verify the accuracy of kinematics solution, and the effectiveness of the proposed control design. Particularly, three experiments are tested in the underwater environment, which verifies its good tracking performance, load carrying and grasping capacity.
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Bates, Nathaniel A., Gregory D. Myer, Rena F. Hale, Nathan D. Schilaty, and Timothy E. Hewett. "Prospective Frontal Plane Angles Used to Predict ACL Strain and Identify Those at High Risk for Sports-Related ACL Injury." Orthopaedic Journal of Sports Medicine 8, no. 10 (October 1, 2020): 232596712095764. http://dx.doi.org/10.1177/2325967120957646.
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Background: Knee abduction moment during landing has been associated with anterior cruciate ligament (ACL) injury. However, accurately capturing this measurement is expensive and technically rigorous. Less complex variables that lend themselves to easier clinical integration are desirable. Purpose: To corroborate in vitro cadaveric simulation and in vivo knee abduction angles from landing tasks to allow for estimation of ACL strain in live participants during a landing task. Study Design: Descriptive laboratory study. Methods: A total of 205 female high school athletes previously underwent prospective 3-dimensional motion analysis and subsequent injury tracking. Differences in knee abduction angle between those who went on to develop ACL injury and healthy controls were assessed using Student t tests and receiver operating characteristic analysis. A total of 11 cadaveric specimens underwent mechanical impact simulation while instrumented to record ACL strain and knee abduction angle. Pearson correlation coefficients were calculated between these variables. The resultant linear regression model was used to estimate ACL strain in the 205 high school athletes based on their knee abduction angles. Results: Knee abduction angle was greater for athletes who went on to develop injury than for healthy controls ( P < .01). Knee abduction angle at initial contact predicted ACL injury status with 78% sensitivity and 83% specificity, with a threshold of 4.6° of knee abduction. ACL strain was significantly correlated with knee abduction angle during cadaveric simulation ( P < .01). Subsequent estimates of peak ACL strain in the high school athletes were greater for those who went on to injury (7.7-8.1% ± 1.5%) than for healthy controls (4.1-4.5% ± 3.6%) ( P < .01). Conclusion: Knee abduction angle exhibited comparable reliability with knee abduction moment for ACL injury risk identification. Cadaveric simulation data can be extrapolated to estimate in vivo ACL strain. Athletes who went on to ACL injury exhibited greater knee abduction and greater ACL strain than did healthy controls during landing. Clinical Relevance: These important associations between the in vivo and cadaveric environments allow clinicians to estimate peak ACL strain from observed knee abduction angles. Neuromuscular control of knee abduction angle during dynamic tasks is imperative for knee joint health. The present associations are an important step toward the establishment of a minimal clinically important difference value for ACL strain during landing.
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Singh, Satwinder, and Ekta Singla. "Service Arms with Unconventional Robotic Parameters for Intricate Workstations: Optimal Number and Dimensional Synthesis." Journal of Robotics 2016 (2016): 1–11. http://dx.doi.org/10.1155/2016/3537068.
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A task-oriented design strategy is presented in this paper for service manipulators. The tasks are normally defined in the form of working locations where the end-effector can work while avoiding the obstacles. To acquire feasible solutions in cluttered environments, the robotic parameters (D-H parameters) are allowed to take unconventional values. This enhances the solution space and it is observed that, by inducing this flexibility, the required number of degrees of freedom for fulfilling a given task can be reduced. A bilevel optimization problem is formulated with the outer layer utilizing the binary search method for minimizing the number of degrees of freedom. To enlarge the applicability domain of the proposed strategy, the upper limit of the number of joints is kept more than six. These allowable redundant joints would help in providing solution for intricate workcells. For each iteration of the upper level, a constrained nonlinear problem is solved for dimensional synthesis of the manipulator. The methodology is demonstrated through a case study of a realistic environment of a cluttered server room. A7-link service arm, synthesized using the proposed method, is able to fulfill two different tasks effectively.
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Babiński, Aleksander, and Janusz Falecki. "Joint Operations of the Polish Armed Forces and the Police." Internal Security 9, no. 1 (December 29, 2017): 0. http://dx.doi.org/10.5604/01.3001.0010.7464.
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Task performance in the area of counteraction and removal of contemporary threats results requires a state to use all of its possible sources and resources. Main entities that carry out those tasks are Armed Forces of the Republic of Poland and Polish Police. Important areas of Polish Armed Forces and Police activities include tasks in the field of crisis management, security and public order maintenance, as well as country’s defence. An effective task performance in particular areas is highly reliant on the quality of joint operations of the entities. Different legislative acts only slightly define powers to organize joint operations by Armed Forces and Police, however, the rules of such operations are described in detail in the agreements concluded between them. The area of joint operations of Polish Armed Forces and Police which should be of much attention is a good organization of joint training courses and field exercises. Such undertakings would significantly improve the effectiveness of joint operations of the entities, consequently reducing the number of victims and material loss, improving the protection of natural environment and providing the state security at a high level.
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Afrati, Foto, Zaid Momani, and Nikos Stasinopoulos. "Cross-Checking Multiple Data Sources Using Multiway Join in MapReduce." Scientific Programming 2017 (2017): 1–9. http://dx.doi.org/10.1155/2017/3072813.
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As data sources accumulate information and data size escalates it becomes more and more difficult to maintain the correctness and validity of these datasets. Therefore, tools must emerge to facilitate this daunting task. Fact checking usually involves a large number of data sources that talk about the same thing but we are not sure which holds the correct information or which has any information at all about the query we care for. A join among all or some data sources can guide us through a fact-checking process. However, when we want to perform this join on a distributed computational environment such as MapReduce, it is not obvious how to distribute efficiently the records in the data sources to the reduce tasks in order to join any subset of them in a single MapReduce job. To this end, we propose an efficient approach using the multiway join to cross-check these data sources in a single round.