Journal articles: 'Kinematics and compliance'

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Dufek, Janet S., John A. Mercer, and Janet R. Griffin. "The Effects of Speed and Surface Compliance on Shock Attenuation Characteristics for Male and Female Runners." Journal of Applied Biomechanics 25, no. 3 (August 2009): 219–28. http://dx.doi.org/10.1123/jab.25.3.219.

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The purpose of the study was to examine the effects of running speed and surface compliance on shock attenuation (SA) characteristics for male and female runners. We were also interested in identifying possible kinematic explanations, specifically, kinematics of the lower extremity at foot-ground contact, for anticipated gender differences in SA. Fourteen volunteer recreational runners (7 male, 7 female) ran at preferred and slow speeds on an adjustable bed treadmill, which simulated soft, medium, and hard surface conditions. Selected kinematic descriptors of lower extremity kinematics as well as leg and head peak impact acceleration values were obtained for 10 left leg contacts per subject-condition. Results identified significant SA values between genders across conditions and more specifically, across surfaces for females, with male runners demonstrating a similar trend. Regression modeling to predict SA by gender for surface conditions elicited unremarkable results, ranging from 30.9 to 59.9% explained variance. It appears that surface compliance does affect SA during running; however, the runner’s ability to dissipate the shock wave may not be expressly explained by our definition of lower extremity kinematics at contact.

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Zhan, Jun, Jiang Li Lu, and Xin Guan. "Test Method of Suspension Kinematics and Compliance." Applied Mechanics and Materials 278-280 (January 2013): 14–17. http://dx.doi.org/10.4028/www.scientific.net/amm.278-280.14.

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For the wide use of the suspension K&C test rig, this paper presents the basic requirements of the vehicle suspension K&C test and provides a reference for unifying the test methods and the test standards. Then, it also gives the specific test specifications and requirements of the vertical wheel jump test, the roll test, the longitudinal force test, and the lateral force test. Finally, the main indicators of the suspension, the steering system and the tire can be obtained.

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Schütte, Jan, and Walter Sextro. "Tire Wear Reduction Based on an Extended Multibody Rear Axle Model." Vehicles 3, no. 2 (May 18, 2021): 233–56. http://dx.doi.org/10.3390/vehicles3020015.

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To analyze the influence of suspension kinematics on tire wear, detailed simulation models are required. In this study, a non-linear, flexible multibody model of a rear axle system is built up in the simulation software MSC Adams/View. The physical model comprises the suspension kinematics, compliance, and dynamics as well as the non-linear behavior of the tire using the FTire model. FTire is chosen because it has a separate tire tread model to compute the contact pressure and friction force distribution in the tire contact patch. To build up the simulation model, a large amount of data is needed. Bushings, spring, and damper characteristics are modeled based on measurements. For the structural components (e.g., control arms), reverse engineering techniques are used. The components are 3D-scanned, reworked, and included as a modal reduced finite element (FE)-model using component mode synthesis by Craig–Bampton. Finally, the suspension model is validated by comparing the simulated kinematic and compliance characteristics to experimental results. To investigate the interaction of suspension kinematics and tire wear, straight line driving events, such as acceleration, driving with constant velocity, and deceleration, are simulated with different setups of wheel suspension kinematics. The influence of the setups on the resulting friction work between tire and road is examined, and an exemplarily calculation of tire wear based on a validated FTire tire model is carried out. The results demonstrate, on the one hand, that the chosen concept of elasto-kinematic axle leads to a relatively good match with experimental results and, on the other hand, that there are significant possibilities to reduce tire wear by adjusting the suspension kinematics.

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Wang, Meng, Elmar Beeh, David Krüger, and Horst E. Friedrich. "Topological optimization of a suspension concept considering the kinematics and compliance performance and the geometric non-linearity." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 232, no. 3 (August 28, 2017): 318–29. http://dx.doi.org/10.1177/0954407017701281.

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This paper proposes a structure design approach for a suspension concept based on topological optimization. In this approach, the kinematics and compliance requirements and the geometric non-linearity are introduced into the structural optimization in order to generate a new lightweight suspension structure and to simplify the iterative design steps between the mechanical requirements and the kinematics and compliance requirements. In the suspension concept, the electric motors are integrated into the longitudinal arms. This concept needs a new suspension linkage with a lightweight structure. For the cases with suspension compliance, linear implicit optimization is used in the design; for the cases with suspension kinematics, the equivalent static load method for implicit optimization with a geometric non-linearity is employed to seek the optimum. By this approach, a suspension structure is obtained. This structure has a better kinematics and compliance performance with a reduced mass than the reference suspension does.

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Valdivia y Alvarado, Pablo, and Kamal Youcef-Toumi. "Design of Machines With Compliant Bodies for Biomimetic Locomotion in Liquid Environments." Journal of Dynamic Systems, Measurement, and Control 128, no. 1 (September 19, 2005): 3–13. http://dx.doi.org/10.1115/1.2168476.

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The aim of this work is to investigate alternative designs for machines intended for biomimetic locomotion in liquid environments. For this, structural compliance instead of discrete assemblies is used to achieve desired mechanism kinematics. We propose two models that describe the dynamics of special compliant mechanisms that can be used to achieve biomimetic locomotion in liquid environments. In addition, we describe the use of analytical solutions for mechanism design. Prototypes that implement the proposed compliant mechanisms are presented and their performance is measured by comparing their kinematic behavior and ultimate locomotion performance with the ones of real fish. This study shows that simpler, more robust mechanisms, as the ones described in this paper, can display comparable performance to existing designs.

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Hayabuchi, Yasunobu, Akemi Ono, Yukako Homma, and Shoji Kagami. "Assessment of pulmonary arterial compliance evaluated using harmonic oscillator kinematics." Pulmonary Circulation 7, no. 3 (June 16, 2017): 666–73. http://dx.doi.org/10.1177/2045893217714781.

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We hypothesized that KPA, a harmonic oscillator kinematics-derived spring constant parameter of the pulmonary artery pressure (PAP) profile, reflects PA compliance in pediatric patients. In this prospective study of 33 children (age range = 0.5–20 years) with various cardiac diseases, we assessed the novel parameter designated as KPA calculated using the pressure phase plane and the equation KPA = (dP/dt_max)2/([Pmax – Pmin])/2)2, where dP/dt_max is the peak derivative of PAP, and Pmax – Pmin is the difference between the minimum and maximum PAP. PA compliance was also calculated using two conventional methods: systolic PA compliance (sPAC) was expressed as the stroke volume/Pmax – Pmin; and diastolic PA compliance (dPAC) was determined according to a two-element Windkessel model of PA diastolic pressure decay. In addition, data were recorded during abdominal compression to determine the influence of preload on KPA. A significant correlation was observed between KPA and sPAC (r = 0.52, P = 0.0018), but not dPAC. Significant correlations were also seen with the time constant (τ) of diastolic PAP (r = −0.51, P = 0.0026) and the pulmonary vascular resistance index (r = −0.39, P = 0.0242). No significant difference in KPA was seen between before and after abdominal compression. KPA had a higher intraclass correlation coefficient than other compliance and resistance parameters for both intra-observer and inter-observer variability (0.998 and 0.997, respectively). These results suggest that KPA can provide insight into the underlying mechanisms and facilitate the quantification of PA compliance.

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Brahmi, Brahim, Maarouf Saad, Abdelkrim Brahmi, Cristobal Ochoa Luna, and Mohammad Habibur Rahman. "Compliant control for wearable exoskeleton robot based on human inverse kinematics." International Journal of Advanced Robotic Systems 15, no. 6 (November 1, 2018): 172988141881213. http://dx.doi.org/10.1177/1729881418812133.

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Rehabilitation robots are a new technology dedicated to the physiotherapy and assistance motion and has aroused great interest in the scientific community. These kinds of robots have shown a high potential in limiting the patient’s disability, increasing its functional movements and helping him/her in daily living activities. This technology is still an emerging area and suffers from many challenges like compliance control and human–robot collaboration. The main challenge addressed in this research is to ensure that the exoskeleton robot provides an appropriate compliance control that allows it to interact perfectly with humans. This article investigates a new compliant control based on a second-order sliding mode with adaptive-gain incorporating time delay estimation. The control uses human inverse kinematics to complete active rehabilitation protocols for an exoskeleton robot with unknown dynamics and unforeseen disturbances. The stability analysis is formulated and demonstrated based on Lyapunov function. An experimental physiotherapy session with three healthy subjects was set up to test the effectiveness of the proposed control, using virtual reality environment.

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Tian, Yingzhong, Mingxuan Luan, Xu Gao, Wenbin Wang, and Long Li. "Kinematic Analysis of Continuum Robot Consisted of Driven Flexible Rods." Mathematical Problems in Engineering 2016 (2016): 1–7. http://dx.doi.org/10.1155/2016/6984194.

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This paper presents the kinematic analysis of a continuum bionic robot with three flexible actuation rods. Since the motion of the end-effector is actuated by the deformation of the rods, the robot structure is with high elasticity and good compliance and the kinematic analysis of the robot requires special treatment. We propose a kinematic model based on the geometry with constant curvature. The analysis consists of two independent mappings: a general mapping for the kinematics of all robots and a specific mapping for this kind of robots. Both of those mappings are developed for the single section and for the multisections. We aim at providing a guide for kinematic analysis of the similar manipulators through this paper.

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Marigold, Daniel S., and Aftab E. Patla. "Adapting Locomotion to Different Surface Compliances: Neuromuscular Responses and Changes in Movement Dynamics." Journal of Neurophysiology 94, no. 3 (September 2005): 1733–50. http://dx.doi.org/10.1152/jn.00019.2005.

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Knowledge of how the nervous system deals with surfaces with different physical properties such as compliance that challenge balance during locomotion is of importance as we are constantly faced with these situations every day. The purpose of this study was to examine the control of center of mass (COM) and lower limb dynamics and recovery response modulation of muscle activity during locomotion across an unexpected compliant surface and in particular, scaling behavior across different levels of compliance. Eight young adults walked along a walkway and stepped on an unexpected compliant surface in the middle of the travel path. There were three different levels of surface compliance, and participants experienced either no compliant surface or one of the three compliant surfaces during each trial that were presented in a blocked or random fashion. Whole body kinematics were collected along with surface electromyography (EMG) of selected bilateral lower limb and trunk muscles. The recovery response to the first compliant-surface trial demonstrated muscle onset latencies between 97 and 175 ms, and activity was modulated while on the compliant surface. Vertical COM trajectory was not preserved after contact with the compliant surface: peak vertical COM, while on the compliant surface was lower than when on stable ground. Perturbed-limb knee flexion after toe-off increased with increased surface compliance, which enabled toe clearance with the ground to be similar to control trials. The results suggest that stepping off of a compliant surface is actively modulated by the CNS and is geared toward maintaining dynamic stability.

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Liu, Xin-Jun, Jay il Jeong, and Jongwon Kim. "A three translational DoFs parallel cube-manipulator." Robotica 21, no. 6 (October 24, 2003): 645–53. http://dx.doi.org/10.1017/s0263574703005198.

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This paper concerns the presentation and analysis of a type of three translational degrees of freedom (DoFs) parallel cube-manipulator. The parallel manipulators are the topology architectures of the DELTA robot and Tsai's manipulator, respectively, which have three translational DoFs. In the design, the three actuators are arranged according to the Cartesian coordinate system, which means that the actuating directions are normal to each other, and the joints connecting to the moving platform are located on three sides of a cube, for such reason we call this type of manipulator the parallel cube-manipulator. The kinematics problems, singularity, workspace, compliance characteristic of the manipulator are investigated in the paper. The analysis results show that the manipulators have the advantages of no singularities in the workspace, relatively more simple forward kinematics, and existence of a compliance center. The parallel cube-manipulator can be applied to the fields of micro-motion manipulators, remote center compliance (RCC) devices, assembly, and so on.

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Twiste, Martin, Chris Nester, Laurence Kenney, and Shyam Rithalia. "The effect of longitudinal compliance on amputee gait kinetics and knee kinematics." Gait & Posture 24 (December 2006): S150—S151. http://dx.doi.org/10.1016/j.gaitpost.2006.11.104.

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Liang, Peidong, Lianzheng Ge, Yihuan Liu, Lijun Zhao, Ruifeng Li, and Ke Wang. "An Augmented Discrete-Time Approach for Human-Robot Collaboration." Discrete Dynamics in Nature and Society 2016 (2016): 1–13. http://dx.doi.org/10.1155/2016/9126056.

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Human-robot collaboration (HRC) is a key feature to distinguish the new generation of robots from conventional robots. Relevant HRC topics have been extensively investigated recently in academic institutes and companies to improve human and robot interactive performance. Generally, human motor control regulates human motion adaptively to the external environment with safety, compliance, stability, and efficiency. Inspired by this, we propose an augmented approach to make a robot understand human motion behaviors based on human kinematics and human postural impedance adaptation. Human kinematics is identified by geometry kinematics approach to map human arm configuration as well as stiffness index controlled by hand gesture to anthropomorphic arm. While human arm postural stiffness is estimated and calibrated within robot empirical stability region, human motion is captured by employing a geometry vector approach based on Kinect. A biomimetic controller in discrete-time is employed to make Baxter robot arm imitate human arm behaviors based on Baxter robot dynamics. An object moving task is implemented to validate the performance of proposed methods based on Baxter robot simulator. Results show that the proposed approach to HRC is intuitive, stable, efficient, and compliant, which may have various applications in human-robot collaboration scenarios.

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Zhang, Guoteng, Zhenyu Jiang, Yueyang Li, Hui Chai, Teng Chen, and Yibin Li. "Active compliance control of the hydraulic actuated leg prototype." Assembly Automation 37, no. 3 (August 7, 2017): 356–68. http://dx.doi.org/10.1108/aa-11-2016-160.

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Purpose Legged robots are inevitably to interact with the environment while they are moving. This paper aims to properly handle these interactions. It works to actively control the joint torques of a hydraulic-actuated leg prototype and achieve compliant motion of the leg. Design/methodology/approach This work focuses on the modelling and controlling of a hydraulic-actuated robot leg prototype. First, the design and kinematics of the leg prototype is introduced. Then the linearlized model for the hydraulic actuator is built, and a model-based leg joint torque controller is presented. Furthermore, the virtual model controller is implemented on the prototype leg to achieve active compliance of the leg. Effectiveness of the controllers are validated through the experiments on the physical platform as well as the results from simulations. Findings The hydraulic joint torque controller presented in this paper shows good torque tracking performance. And the actively compliant leg successfully emulates the performance of virtual passive components under dynamic situations. Originality/value The main contribution of this paper is that it proposed a model-based active compliance controller for the hydraulic-actuated robot leg. It will be helpful for those robots that aim to achieve versatile and safe motions.

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Bai, Fan, Kong Hui Guo, and Dang Lu. "Suspension Optimum Design Considering Tire and Vehicle Matching." Applied Mechanics and Materials 496-500 (January 2014): 617–20. http://dx.doi.org/10.4028/www.scientific.net/amm.496-500.617.

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A method of suspension optimum design based on the tire and vehicle matching was introduced in this paper. Firstly, the vehicle handling stability evaluation standards considering tire matching with vehicle were determined by the subjective and objective assessment. Secondly, the quality, suspension kinematics and compliance characteristics and tire mechanics of prototype were tested. The vehicle model of prototype was built in Carsim with the corresponding experiment data. The model was verified by the results of the vehicle handling stability tests. Then a combination simulation platform was developed by making use of Isight, Matlab and Casim. Finally the optimal design of suspension kinematics and compliance characteristics and tire mechanics were conducted, taking straight running performance index, high-speed driving safety index and high-speed cornering performance index as the objective. The simulation results indicated that after optimization, the straight running performance and high-speed cornering performance of prototype could be improved.

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Manion, Charles, Ryan Arlitt, Matthew I. Campbell, Irem Tumer, Rob Stone, and P. Alex Greaney. "Automated design of flexible linkers." Dalton Transactions 45, no. 10 (2016): 4338–45. http://dx.doi.org/10.1039/c5dt03511b.

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This paper presents a method for the systematic and automated design of flexible organic linkers for construction of metal organic-frameworks (MOFs) in which flexibility, compliance, or other mechanically exotic properties originate at the linker level rather than from the framework kinematics.

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Reynaga, Crystal M., Caitrin E. Eaton, Galatea A. Strong, and Emanuel Azizi. "Compliant Substrates Disrupt Elastic Energy Storage in Jumping Tree Frogs." Integrative and Comparative Biology 59, no. 6 (May 29, 2019): 1535–45. http://dx.doi.org/10.1093/icb/icz069.

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Abstract Arboreal frogs navigate complex environments and face diverse mechanical properties within their physical environment. Such frogs may encounter substrates that are damped and absorb energy or are elastic and can store and release energy as the animal pushes off during take-off. When dealing with a compliant substrate, a well-coordinated jump would allow for the recovery of elastic energy stored in the substrate to amplify mechanical power, effectively adding an in-series spring to the hindlimbs. We tested the hypothesis that effective use of compliant substrates requires active changes to muscle activation and limb kinematics to recover energy from the substrate. We designed an actuated force platform, modulated with a real-time feedback controller to vary the stiffness of the substrate. We quantified the kinetics and kinematics of Cuban tree frogs (Osteopilus septentrionalis) jumping off platforms at four different stiffness conditions. In addition, we used electromyography to examine the relationship between muscle activation patterns and substrate compliance during take-off in a knee extensor (m. cruralis) and an ankle extensor (m. plantaris). We find O. septentrionalis do not modulate motor patterns in response to substrate compliance. Although not actively modulated, changes in the rate of limb extension suggest a trade-off between power amplification and energy recovery from the substrate. Our results suggest that compliant substrates disrupt the inertial catch mechanism that allows tree frogs to store elastic energy in the tendon, thereby slowing the rate of limb extension and increasing the duration of take-off. However, the slower rate of limb extension does provide additional time to recover more energy from the substrate. This work serves to broaden our understanding of how the intrinsic mechanical properties of a system may broaden an organism’s capacity to maintain performance when facing environmental perturbations.

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Yu, Guang, Jun Wu, Liping Wang, Zhufeng Shao, and Ying Gao. "Compliance Analysis of a Novel Tool Head with Parallel Kinematics Considering Joint Clearance." Procedia Manufacturing 10 (2017): 71–82. http://dx.doi.org/10.1016/j.promfg.2017.07.025.

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Young, Jesse W., Bethany M. Stricklen, and Brad A. Chadwell. "Effects of support diameter and compliance on common marmoset (Callithrix jacchus) gait kinematics." Journal of Experimental Biology 219, no. 17 (August 31, 2016): 2659–72. http://dx.doi.org/10.1242/jeb.140939.

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Huang, Hsing-Hui, and Si-Liang Chen. "Effect of compliant linkages on suspension under load." Mechanical Sciences 10, no. 2 (October 29, 2019): 505–16. http://dx.doi.org/10.5194/ms-10-505-2019.

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Abstract. A numerical investigation is performed into the effects of rigid and compliant suspension linkages, respectively, on: the kinematics and handling performance of a lightweight electric vehicle (EV). CAE models of the front and rear suspension systems are first established based on the measured parameters of the target vehicle. The validity of the CAE models is confirmed by comparing the results obtained for the camber angle and kingpin inclination angle with those obtained mathematically using the vector loop method. CAE models are then performed using half-vehicle and whole-vehicle models. Quarter-vehicle simulations are then performed to compare the solutions obtained from the compliance and rigid-body models for the forces acting on the hardpoints of the two suspension systems under pothole impact conditions. Finally, whole-vehicle simulations are conducted using both the rigid-body model and the compliance model to evaluate the handling performance of the EV in impulse steering tests conducted at vehicle speeds of 40, 60 and 80 km h−1, respectively. In general, the results show that the choice of a rigid-body model or a compliance model has a significant effect on the forces computed at some of the hardpoints in the front and rear suspension systems. Furthermore, the rigid-body model predicts a better vehicle body stability following high-speed turns than the compliance model.

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Bahat, Hilla Sarig, Dmitry German, Galia Palomo, Hila Gold, and Yael Frankel Nir. "Self-Kinematic Training for Flight-Associated Neck Pain: a Randomized Controlled Trial." Aerospace Medicine and Human Performance 91, no. 10 (October 1, 2020): 790–97. http://dx.doi.org/10.3357/amhp.5546.2020.

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BACKGROUND: Flight-associated neck pain (FANP) is a serious problem in fighter pilots. Despite the high impact of FANP there is little evidence for effective management. However, self-kinematic training showed a positive effect in the general population. The purpose of this study was to investigate the effectiveness of a self-kinematic training program using virtual reality in improving neck pain in fighter pilots.METHODS: There were 45 pilots with FANP who were randomized to a control group (N 23) or a training group (N 22). Training participants were instructed to exercise using a personalized self-training program, for 20 min/wk, for 4 wk. Primary outcome measures were neck disability (NDI%) and mean velocity ( s1), and secondary were pain, health status, accuracy, and isometric strength. Assessments were conducted by a blinded assessor and intention-to-treat analysis by a blinded statistician.RESULTS: There were 40 pilots who completed the postintervention assessments, and 35 completed the 6-mo follow-up. Baseline measurements showed mild pain and disability (mean VAS 43 22.73, NDI 17.76 9.59%) and high kinematic performance. Compliance with self-training was poor. No differences were observed in self-reported measures and strength. Exercise duration was correlated with NDI% improvement.DISCUSSION: This self-kinematic training promoted kinematic performance, but was ineffective in engaging the pilots to exercise, and consequently did not improve pain and disability. Poor compliance was previously reported in self-training for FANP, suggesting further studies should prioritize supervised training. Considering the high baseline kinematic performance, kinematics does not seem to be a key factor in FANP, and future exercise research should aim for intense strengthening to increase endurance to the high Gz pilots experience.Sarig Bahat H, German D, Palomo G, Gold H, Frankel Nir Y. Self-kinematic training for flight-associated neck pain: a randomized controlled trial. Aerosp Med Hum Perform. 2020; 91(10):790797.

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Meier, Horst, Roman Laurischkat, C. Bertsch, and Stefanie Reese. "Prediction of Path Deviation in Robot Based Incremental Sheet Metal Forming by Means of an Integrated Finite Element – Multi Body System Model." Key Engineering Materials 410-411 (March 2009): 365–72. http://dx.doi.org/10.4028/www.scientific.net/kem.410-411.365.

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The main influence on the dimensional accuracy in incremental sheet metal forming results from the compliance of the involved machine structures and the springback effects of the workpiece. This holds especially for robot based sheet metal forming, as the stiffness of the robot’s kinematics compared to a conventional machine tool is low, resulting in a significant deviation of the planned tool path and therefore in a shape of insufficient quality. To predict these deviations, a coupled process structure model has been implemented. It consists of a finite element (FE) approach to simulate the sheet forming and a multi body system (MBS) modeling the compliant robot structure. The forces in the tool tip are computed by the FEA, while the path deviations due to these forces can be obtained using the MBS model. Coupling both models gives the true path driven by the robots. Built on this path prediction, mechanisms to compensate the robot’s kinematics can be implemented. The current paper describes an exemplary model based path prediction and its validation.

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Alon Tzezana, Gali, and Kenneth S. Breuer. "Thrust, drag and wake structure in flapping compliant membrane wings." Journal of Fluid Mechanics 862 (January 15, 2019): 871–88. http://dx.doi.org/10.1017/jfm.2018.966.

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We present a theoretical framework to characterize the steady and unsteady aeroelastic behaviour of compliant membrane wings under different conditions. We develop an analytic model based on thin airfoil theory coupled with a membrane equation. Adopting a numerical solution to the model equations, we study the effects of wing compliance, inertia and flapping kinematics on aerodynamic performance. The effects of added mass and fluid damping on a flapping membrane are quantified using a simple damped oscillator model. As the flapping frequency is increased, membranes go through a transition from thrust to drag around the resonant frequency, and this transition is earlier for more compliant membranes. The wake also undergoes a transition from a reverse von Kármán wake to a traditional von Kármán wake. The wake transition frequency is predicted to be higher than the thrust–drag transition frequency for highly compliant wings.

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Caldwell, Graham E. "Tendon Elasticity and Relative Length: Effects on the Hill Two-Component Muscle Model." Journal of Applied Biomechanics 11, no. 1 (February 1995): 1–24. http://dx.doi.org/10.1123/jab.11.1.1.

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The effects of relative tendon/fiber proportion and tendon elasticity on the force output of the Hill muscle model (a contractile component [CC] in series with an elastic element [SEC]) were examined through computer simulation. Three versions of the Hill model were constructed. Model 1 examined the effect of relative tendon/fiber proportion on CC kinematics and kinetics during an isometric twitch, while Model 2 compared the effect of changes in tendon compliance. These models revealed force profile differences related to alterations in CC velocity, although the reasons underlying the variation in CC kinematics were different. The relative tendon/fiber proportion and tendon compliance differences were examined in combination in Model 3. Test simulations revealed response differences among the three model versions, and therefore verified Alexander and Ker's (1990) contention that the morphology of muscle is related to design criteria. It is suggested that the implementation of generalized muscle models to represent specific units of the musculoskeletal system should be done carefully and that the implementation process itself warrants further study.

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Kim, Sehun, Wenjun Xu, and Hongliang Ren. "Inverse Kinematics with a Geometrical Approximation for Multi-Segment Flexible Curvilinear Robots." Robotics 8, no. 2 (June 19, 2019): 48. http://dx.doi.org/10.3390/robotics8020048.

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Despite research related to flexible or continuum curvilinear robots, there lacks a common simulation tool for continuum robots, which are unlike rigid robots. Thus, in this paper, a robotics toolbox is utilized to model a wire-driven flexible manipulator as one of the continuum robots. Constant curvature property can enable the robotics toolbox to represent the flexible manipulator and validate its kinematics. Moreover, because the closed-form inverse kinematics methods developed previously for real-time control conceded limitations in modeling some continuum robots, we hereby develop an inverse kinematics method for the wire-driven flexible manipulator which can provide fast and reliable inverse results. Experimental results showed that geometrical information offered a stable starting point for the proposed inverse kinematics algorithm. Moreover, the first and second derivatives of a fitness function further contributed to a fast-converging solution within a few microseconds. Lastly, for the potential feasibility of an active compliance controller without physical force/torque sensors, a reaction torque observer was investigated for a flexible manipulator with direct drive mechanisms.

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Ikhsan, N., R. Ramli, and A. Alias. "ANALYSIS OF THE KINEMATICS AND COMPLIANCE OF A PASSIVE SUSPENSION SYSTEM USING ADAMS CAR." Journal of Mechanical Engineering and Sciences 8 (June 30, 2015): 1293–301. http://dx.doi.org/10.15282/jmes.8.2015.4.0126.

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Lv, Tianqi, Yunqing Zhang, Yupeng Duan, and James Yang. "Kinematics & compliance analysis of double wishbone air suspension with frictions and joint clearances." Mechanism and Machine Theory 156 (February 2021): 104127. http://dx.doi.org/10.1016/j.mechmachtheory.2020.104127.

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Ai, Haiping, An Zhu, Jiajia Wang, Xiaoyan Yu, and Li Chen. "Buffer Compliance Control of Space Robots Capturing a Non-Cooperative Spacecraft Based on Reinforcement Learning." Applied Sciences 11, no. 13 (June 22, 2021): 5783. http://dx.doi.org/10.3390/app11135783.

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Aiming at addressing the problem that the joints are easily destroyed by the impact torque during the process of space robot on-orbit capturing a non-cooperative spacecraft, a reinforcement learning control algorithm combined with a compliant mechanism is proposed to achieve buffer compliance control. The compliant mechanism can not only absorb the impact energy through the deformation of its internal spring, but also limit the impact torque to a safe range by combining with the compliance control strategy. First of all, the dynamic models of the space robot and the target spacecraft before capture are obtained by using the Lagrange approach and Newton-Euler method. After that, based on the law of conservation of momentum, the constraints of kinematics and velocity, the integrated dynamic model of the post-capture hybrid system is derived. Considering the unstable hybrid system, a buffer compliance control based on reinforcement learning is proposed for the stable control. The associative search network is employed to approximate unknown nonlinear functions, an adaptive critic network is utilized to construct reinforcement signal to tune the associative search network. The numerical simulation shows that the proposed control scheme can reduce the impact torque acting on joints by 76.6% at the maximum and 58.7% at the minimum in the capturing operation phase. And in the stable control phase, the impact torque acting on the joints were limited within the safety threshold, which can avoid overload and damage of the joint actuators.

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Sadeqi, Soheil, Shaun P. Bourgeois, Edward J. Park, and Siamak Arzanpour. "Design and performance analysis of a 3-RRR spherical parallel manipulator for hip exoskeleton applications." Journal of Rehabilitation and Assistive Technologies Engineering 4 (January 2017): 205566831769759. http://dx.doi.org/10.1177/2055668317697596.

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This paper presents the design and performance analysis and experimental study of a 3-RRR spherical parallel manipulator in the context of hip exoskeleton applications. First, the mechanism’s inverse kinematics analysis and Jacobian matrix development are revisited. Manipulability, dexterity, and rotational sensitivity indices are then evaluated for two different methods of attachment to the human body. The superior attachment method in terms of these performance measures is indicated, and an experimental study based on the selected method is conducted; the experiment involves testing the capability of a 3-RRR manipulator’s end-effector in tracking the motions experienced by a human hip joint during normal gait cycles. Finally, the results of the experimental study indicate that the manipulator represents a feasible hip exoskeleton solution providing total kinematic compliance with the human hip joint’s 3-degree-of-freedom motion capabilities.

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Hirabayashi, Hisaaki, Koichi Sugimoto, Atsuko Enomoto, and Ichirou Ishimaru. "Robot Manipulation Using Virtual Compliance Control." Journal of Robotics and Mechatronics 12, no. 5 (October 20, 2000): 567–76. http://dx.doi.org/10.20965/jrm.2000.p0567.

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Experimental results proved that a unified method of impedance control, already presented as virtual compliance control, can make a robot manipulator without any special mechanism perform various patterns of motion, corresponding to the specified software parameters of the control method. Outcomes demonstrated are as follows. (1) The proposed control method can change the characteristics of spring constant and dashpot constant, that is impedance, of 6 degree of freedom (translational: 3 , rotational: 3) of the robot hand. (2) The change of characteristics mentioned above in (1) can be treated equivalently in both translational and rotational. (3) The change of characteristics mentioned above in (1) and (2) can be implemented in real time. (4) The proposed control method can change the characteristics of transient response in velocity control of 6-d.o.f. of the robot hands. (5) The change of characteristics mentioned above in (4) can be treated equivalently both translationally and rotationally. (6) The change of characteristics mentioned above in (4) and (5) can be implemented in real time. (7) The proposed control method can make impedance control applied to one axis, and position control applied to other axis simultaneously, as to 6-d.o.f. of the robot hands. (8) Experimental results mentioned above in (1) - (7) imply the following advantage and disadvantage; advantage: a unified control method that can perform various patterns of motion by specifying software parameters, disadvantage: control response is not necessarily precise that is because proposed control method is base on not dynamics but kinematics.

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Foster, Kathleen L., and Timothy E. Higham. "Context-dependent changes in motor control and kinematics during locomotion: modulation and decoupling." Proceedings of the Royal Society B: Biological Sciences 281, no. 1782 (May 7, 2014): 20133331. http://dx.doi.org/10.1098/rspb.2013.3331.

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Successful locomotion through complex, heterogeneous environments requires the muscles that power locomotion to function effectively under a wide variety of conditions. Although considerable data exist on how animals modulate both kinematics and motor pattern when confronted with orientation (i.e. incline) demands, little is known about the modulation of muscle function in response to changes in structural demands like substrate diameter, compliance and texture. Here, we used high-speed videography and electromyography to examine how substrate incline and perch diameter affected the kinematics and muscle function of both the forelimb and hindlimb in the green anole ( Anolis carolinensis ). Surprisingly, we found a decoupling of the modulation of kinematics and motor activity, with kinematics being more affected by perch diameter than by incline, and muscle function being more affected by incline than by perch diameter. Also, muscle activity was most stereotyped on the broad, vertical condition, suggesting that, despite being classified as a trunk-crown ecomorph, this species may prefer trunks. These data emphasize the complex interactions between the processes that underlie animal movement and the importance of examining muscle function when considering both the evolution of locomotion and the impacts of ecology on function.

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Gilman, C. A., M. D. Bartlett, G. B. Gillis, and D. J. Irschick. "Total recoil: perch compliance alters jumping performance and kinematics in green anole lizards (Anolis carolinensis)." Journal of Experimental Biology 215, no. 2 (December 21, 2011): 220–26. http://dx.doi.org/10.1242/jeb.061838.

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Gilman, C. A., M. Bartlett, G. Gillis, and D. Irschick. "Total recoil: perch compliance alters jumping performance and kinematics in green anole lizards (Anolis carolinensis)." Journal of Experimental Biology 215, no. 3 (January 12, 2012): 568. http://dx.doi.org/10.1242/jeb.069724.

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Wei, T. E., and H. R. Dorfi. "Vehicle Suspension Measurements: Evaluation of the Benefits of Dynamic over Quasistatic Kinematics and Compliance Testing3." Tire Science and Technology 37, no. 1 (March 1, 2009): 32–46. http://dx.doi.org/10.2346/1.3078489.

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Abstract Vehicle dynamics packages can be used to simulate handling or braking maneuvers that would otherwise need to be performed outdoors. Many of the parameters for these types of vehicle models are determined through kinematics and compliance (K&C) measurements. Machines that perform these measurements apply various forces or moments and measure the response of the vehicle. The rate that these forces or moments are applied can be quasistatic or dynamic. Machines that are capable of performing dynamic tests are more expensive due to the need for inertia compensation, sensors that can acquire data at higher rates, and larger actuators or hydraulic power supplies. However, it is possible that measurements of dynamic vehicle response may increase the fidelity of parameter identification, compared to the sole use of quasistatic tests. One reason that parameter identification may be more accurate is the rate of force and moment application in dynamic tests is more like those in the actual maneuvers that are desirable to simulate. A study was performed to determine where the advantages of performing dynamic K&C testing lie. Quasistatic K&C tests, along with dynamic tests performed at several frequencies up to 3.0 Hz, were performed on the front axle of a front-wheel drive compact sedan, using an MTS Systems High-Rate K&C Machine. Assessment of any advantages of dynamic K&C testing has been made through correlations of the vehicle response between dynamic and quasistatic tests.

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Gao, Jin, and Fuquan Wu. "Analysis and optimization of the vehicle handling stability with considering suspension kinematics and compliance characteristics." Advances in Mechanical Engineering 13, no. 5 (May 2021): 168781402110155. http://dx.doi.org/10.1177/16878140211015523.

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The dynamic model of the front double wishbone suspension and the rear multi-link suspension of the vehicle are established. On the basis of detailed analysis of suspension kinematics, calculation method of wheel alignment angle and force calculation of suspension bushing, the influence mechanism of suspension bushing on the vehicle transient state is clarified, and the vehicle transient characteristic index is derived from the vehicle three-free dynamic model. The sensitivity analysis of the suspension bushing is carried out, and the bushing stiffness which has a great influence on the transient state of the vehicle is obtained. The bushing stiffness scale factor is used as the optimization variable, the vehicle transient characteristic index is used as the optimization target, and the NSGA-II optimization algorithm is used for multi-objective optimization. After optimization, one Pareto solution is selected to compare with the original vehicle, the comparison results show that the yaw rate gain, resonance frequency and delay time of yaw rate in the vehicle transient characteristic index are all improved, other optimization targets change less. In the steady-state comparison, the understeer tendency of the vehicle increases, and the roll angle of the vehicle increases but is within an acceptable range.

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Allen, Emily, and John Swensen. "Directional Stiffness Control Through Geometric Patterning and Localized Heating of Field’s Metal Lattice Embedded in Silicone." Actuators 7, no. 4 (November 27, 2018): 80. http://dx.doi.org/10.3390/act7040080.

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This research explores a new realm of soft robotic materials where the stiffness magnitude, directionality, and spatial resolution may be precisely controlled. These materials mimic biological systems where localized muscle contractions and adjustment of tissue stiffness enables meticulous, intelligent movement. Here we propose the use of a low-melting-point (LMP) metal lattice structure as a rigid frame using localized heating to allow compliance about selectable axes along the lattice. The resulting shape of the lattice is modeled using product of exponentials kinematics to describe the serial chain of tunably compliant axes; this model is found to match the behavior of the physical test piece consisting of a Field’s metal (FM) lattice encased in silicone rubber. This concept could enable highly maneuverable robotic structures with significantly improved dexterity.

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Liang, Qiaokang, Dan Zhang, Yaonan Wang, and Yunjian Ge. "Design and Analysis of a Novel Six-Component F/T Sensor based on CPM for Passive Compliant Assembly." Measurement Science Review 13, no. 5 (October 1, 2013): 253–64. http://dx.doi.org/10.2478/msr-2013-0038.

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Abstract This paper presents the design and analysis of a six-component Force/Torque (F/T) sensor whose design is based on the mechanism of the Compliant Parallel Mechanism (CPM). The force sensor is used to measure forces along the x-, y-, and z-axis (Fx, Fy and Fz) and moments about the x-, y-, and z-axis (Mx, My and Mz) simultaneously and to provide passive compliance during parts handling and assembly. Particularly, the structural design, the details of the measuring principle and the kinematics are presented. Afterwards, based on the Design of Experiments (DOE) approach provided by the software ANSYS®, a Finite Element Analysis (FEA) is performed. This analysis is performed with the objective of achieving both high sensitivity and isotropy of the sensor. The results of FEA show that the proposed sensor possesses high performance and robustness.

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Moon, I. D., and C. Y. Oh. "Computational model for analyzing the kinematics and compliance characteristics of a commercial vehicle’s front suspension system." International Journal of Automotive Technology 13, no. 2 (January 29, 2012): 279–84. http://dx.doi.org/10.1007/s12239-012-0025-4.

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WHITNEY, J. P., and R. J. WOOD. "Aeromechanics of passive rotation in flapping flight." Journal of Fluid Mechanics 660 (July 27, 2010): 197–220. http://dx.doi.org/10.1017/s002211201000265x.

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Flying insects and robots that mimic them flap and rotate (or ‘pitch’) their wings with large angular amplitudes. The reciprocating nature of flapping requires rotation of the wing at the end of each stroke. Insects or flapping-wing robots could achieve this by directly exerting moments about the axis of rotation using auxiliary muscles or actuators. However, completely passive rotational dynamics might be preferred for efficiency purposes, or, in the case of a robot, decreased mechanical complexity and reduced system mass. Herein, the detailed equations of motion are derived for wing rotational dynamics, and a blade-element model is used to supply aerodynamic force and moment estimates. Passive-rotation flapping experiments with insect-scale mechanically driven artificial wings are conducted to simultaneously measure aerodynamic forces and three-degree-of-freedom kinematics (flapping, rotation and out-of-plane deviation), allowing a detailed evaluation of the blade-element model and the derived equations of motion. Variations in flapping kinematics, wing-beat frequency, stroke amplitude and torsional compliance are made to test the generality of the model. All experiments showed strong agreement with predicted forces and kinematics, without variation or fitting of model parameters.

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Marcinkevičius, Andrejus Henrikas. "Analysis of Work Accuracy Dependencies on Design of a Device for Control of Workpiece Dimensions and Compliance at Machining." Solid State Phenomena 113 (June 2006): 471–76. http://dx.doi.org/10.4028/www.scientific.net/ssp.113.471.

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Work accuracy dependencies of a new scheme device for automatic dimension control and follow rest at machining of multi step shaft are analyzed. The device can automatically reset from control and the support of one step of a shaft to the other and can be used on programmed cylindrical grinders or lathes. Errors connected with the kinematics scheme and showing in static and uprising at working of a device are analyzed and ways of their decreasing are shown.

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Karande, Sandesh R., Lenin Babu Mailan Chinnapandi, P. Jeyaraj, and Jeyanthi Subramanian. "Kinematics and compliance analysis of active suspension system and Development of control algorithm to maximize ride comfort." IOP Conference Series: Materials Science and Engineering 1128, no. 1 (April 1, 2021): 012044. http://dx.doi.org/10.1088/1757-899x/1128/1/012044.

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GRAU, Jan, Matej SULITKA, and Pavel SOUCEK. "INFLUENCE OF LINEAR FEED DRIVE CONTROLLER SETTING IN CNC TURNING LATHE ON THE STABILITY OF MACHINING." Journal of Machine Engineering 19, no. 2 (June 9, 2019): 18–31. http://dx.doi.org/10.5604/01.3001.0013.2221.

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The paper deals with the influence of linear feed drive controller setting of a CNC turning lathe on the stability of machining. A coupled simulation model of feed drive control and ball screw drive mechanics with a transmission belt was created and validated by the feed drive diagnostic measurements. The influence of drive control on the overall dynamic compliance at the TCP and the limits of stable depth of cut was examined. Impact of the feed drive actual kinematics configuration on the stability limits was studied as well.

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Lu, Y., B. Hu, and J. Yu. "Analyses of the stiffness and elastic deformation of a 2(3-SPR) serial—parallel manipulator." Proceedings of the Institution of Mechanical Engineers, Part K: Journal of Multi-body Dynamics 223, no. 3 (April 30, 2009): 189–98. http://dx.doi.org/10.1243/14644193jmbd199.

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Stiffness is one of the important indices for evaluating the performances of serial—parallel manipulators (S—PMs), particularly when the S—PMs are used as machine tools and the robot arm/leg, and higher stiffness allows higher machining speed with higher accuracy of the end-effector. In this article, the stiffness and the elastic deformation of a 2(3-SPR) S—PM are studied systematically. First, a 2(3-SPR) S—PM, including an upper 3-SPR parallel manipulator (PM) and a lower 3-SPR PM, is constructed, and its characteristics are analysed. Second, some formulae for solving the elastic deformation and the compliance matrix of the active legs are derived from the available kinematics/statics of this S—PM. Third, based on the principle of virtual work and the compliance matrix of the active legs, the elastic deformation and the total stiffness matrix of this S—PM are solved and analysed.

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Liu, Jingfang, Yanxia Cheng, Shuang Zhang, Zhenxin Lu, and Guohua Gao. "Design and Analysis of a Rigid-Flexible Parallel Mechanism for a Neck Brace." Mathematical Problems in Engineering 2019 (November 3, 2019): 1–20. http://dx.doi.org/10.1155/2019/9014653.

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A rigid-flexible parallel mechanism called 3-RXS mechanism as a neck brace for patients with head drooping symptoms (HDS) is presented. The 3-RXS neck brace has a simple and light structure coupled with good rotation performance, so it can be used to assist the neck to achieve flexion and extension, lateral bend, and axial torsion. Firstly, to prove that the X-shaped compliant joint has a rotational degree of freedom (DoF) and can be used in the 3-RRS spherical parallel mechanism (3-RRS SPM), the six-dimensional compliance matrix, axis drift, and DoF of the X-shaped compliant joint have been systematically calculated. Secondly, the 3-RXS mechanism and its pseudo-rigid-body model (PRBM) are obtained by replacing the revolute pair with the X-shaped compliant joint in the 3-RRS SPM. The rotation workspace of the 3-RXS mechanism is also performed. Finally, to verify the rotation function and effect of 3-RXS mechanism for neck-assisted rehabilitation, the kinematics simulations of the 3-RXS and 3-RRS mechanisms are carried out and compared with the theoretical result, and a primary experiment for rotation measurement of 3-RXS mechanism prototype is carried out. All results prove the feasibility of the 3-RXS mechanism for a neck brace.

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Brand, Andreas, Isabella Klöpfer-Krämer, Mario Morgenstern, Inga Kröger, Björn Michel, Andreas Thannheimer, Janina Anna Müßig, and Peter Augat. "Effects of knee orthosis adjustment on biomechanical performance and clinical outcome in patients with medial knee osteoarthritis." Prosthetics and Orthotics International 41, no. 6 (February 19, 2017): 587–94. http://dx.doi.org/10.1177/0309364617691623.

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Background: Valgus bracing in medial knee osteoarthritis aims to improve gait function by reducing the loading of the medial compartment. Orthosis composition and optimal adjustment is essential to achieve biomechanical and clinical effectiveness. Objectives: To investigate biomechanical functionality during gait, pain relief and compliance in patients with knee osteoarthritis using a lightweight adjustable knee unloader orthosis. Study Design: Prospective observational clinical trial. Methods: Instrumented gait analysis in 22 patients with unilateral medial knee osteoarthritis was performed after a 2-week orthosis acclimatisation period. Kinematics and kinetics during gait as well as force transmission from the orthosis to the knee were analysed. Measurements were performed without, at individualised and at reduced orthosis setting. The assessment was supplemented by patient-related pain sensation and compliance questionnaires. Results: Orthosis wear significantly reduced the knee adduction moment by up to 20% depending on orthosis adjustment, whereas pain sensation was significantly reduced by 16%. A significant positive correlation was found between force transmissions and knee adduction moment as well as for frontal knee angle. Compliance was good with a main daily use of 2–6 h. Conclusion: The orthosis provides significant biomechanical improvements, pain relief and good patient compliance. Patients had a biomechanical benefit for the individualised and reduced orthosis adjustments. Clinical relevance In patients with medial knee osteoarthritis, a lightweight medial unloader orthosis effectively reduced external knee adduction moment and pain sensation during daily activities. Thus, use of lightweight orthoses effectively supports conservative treatment in medial knee osteoarthritis.

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Fu, Qiyuan, Sean W. Gart, Thomas W. Mitchel, Jin Seob Kim, Gregory S. Chirikjian, and Chen Li. "Lateral Oscillation and Body Compliance Help Snakes and Snake Robots Stably Traverse Large, Smooth Obstacles." Integrative and Comparative Biology 60, no. 1 (March 26, 2020): 171–79. http://dx.doi.org/10.1093/icb/icaa013.

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Abstract Snakes can move through almost any terrain. Similarly, snake robots hold the promise as a versatile platform to traverse complex environments such as earthquake rubble. Unlike snake locomotion on flat surfaces which is inherently stable, when snakes traverse complex terrain by deforming their body out of plane, it becomes challenging to maintain stability. Here, we review our recent progress in understanding how snakes and snake robots traverse large, smooth obstacles such as boulders and felled trees that lack “anchor points” for gripping or bracing. First, we discovered that the generalist variable kingsnake combines lateral oscillation and cantilevering. Regardless of step height and surface friction, the overall gait is preserved. Next, to quantify static stability of the snake, we developed a method to interpolate continuous body in three dimensions (3D) (both position and orientation) between discrete tracked markers. By analyzing the base of support using the interpolated continuous body 3-D kinematics, we discovered that the snake maintained perfect stability during traversal, even on the most challenging low friction, high step. Finally, we applied this gait to a snake robot and systematically tested its performance traversing large steps with variable heights to further understand stability principles. The robot rapidly and stably traversed steps nearly as high as a third of its body length. As step height increased, the robot rolled more frequently to the extent of flipping over, reducing traversal probability. The absence of such failure in the snake with a compliant body inspired us to add body compliance to the robot. With better surface contact, the compliant body robot suffered less roll instability and traversed high steps at higher probability, without sacrificing traversal speed. Our robot traversed large step-like obstacles more rapidly than most previous snake robots, approaching that of the animal. The combination of lateral oscillation and body compliance to form a large, reliable base of support may be useful for snakes and snake robots to traverse diverse 3-D environments with large, smooth obstacles.

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Kurokawa, Sadao, Tetsuo Fukunaga, and Senshi Fukashiro. "Behavior of fascicles and tendinous structures of human gastrocnemius during vertical jumping." Journal of Applied Physiology 90, no. 4 (April 1, 2001): 1349–58. http://dx.doi.org/10.1152/jappl.2001.90.4.1349.

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Behavior of fascicles and tendinous structures of human gastrocnemius medialis (MG) was determined by use of ultrasonography in vivo during jumping. Eight male subjects jumped vertically without countermovement (squat jump, SQJ). Simultaneously, kinematics, kinetics, and electromyography from lower leg muscles were recorded during SQJ. During phase I (−350 to −100 ms before toe-off), muscle-tendon complex (MTC) length was almost constant. Fascicles, however, shortened by 26%, and tendinous structures were stretched by 6%, storing elastic energy of 4.9 J during phase I. During phase II (−100 ms to toe-off), although fascicles generated force quasi-isometrically, MTC shortened rapidly by 5.3%, releasing prestored elastic energy with a higher peak positive power than that of fascicles. Also, the compliance of tendinous structures in vivo was somewhat higher than that of external tendon used in the simulation studies. The results demonstrate that the compliance of tendinous structures, together with no yielding of muscle fibers, allows MTC to effectively generate relatively large power at a high joint angular velocity region during the last part of push-off.

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Zadarnowska, Katarzyna, and Krzysztof Tchoń. "A control theory framework for performance evaluation of mobile manipulators." Robotica 25, no. 6 (November 2007): 703–15. http://dx.doi.org/10.1017/s0263574707003803.

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SUMMARYWe propose a new, control theoretic methodology for defining performance measures of mobile manipulators. As a guiding principle, we assume that the kinematics or the dynamics of a mobile manipulator are represented by the end point map of a control system with outputs, and that a locally controllable system yields nontrivial performance measures. In the paper, we focus on two categories of dynamic performance measures: the compliance measure and the admittance measure. In both these categories, the following local and global performance characteristics are introduced: the agility ellipsoid, the agility and mobility, the condition number and the distortion. The usefulness of new local measures is demonstrated on the example of determining optimal motion patterns of a wheeled mobile robot.

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Campisano, Federico, Simone Caló, Andria A. Remirez, James H. Chandler, Keith L. Obstein, Robert J. Webster, and Pietro Valdastri. "Closed-loop control of soft continuum manipulators under tip follower actuation." International Journal of Robotics Research 40, no. 6-7 (March 15, 2021): 923–38. http://dx.doi.org/10.1177/0278364921997167.

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Continuum manipulators, inspired by nature, have drawn significant interest within the robotics community. They can facilitate motion within complex environments where traditional rigid robots may be ineffective, while maintaining a reasonable degree of precision. Soft continuum manipulators have emerged as a growing subfield of continuum robotics, with promise for applications requiring high compliance, including certain medical procedures. This has driven demand for new control schemes designed to precisely control these highly flexible manipulators, whose kinematics may be sensitive to external loads, such as gravity. This article presents one such approach, utilizing a rapidly computed kinematic model based on Cosserat rod theory, coupled with sensor feedback to facilitate closed-loop control, for a soft continuum manipulator under tip follower actuation and external loading. This approach is suited to soft manipulators undergoing quasi-static deployment, where actuators apply a follower wrench (i.e., one that is in a constant body frame direction regardless of robot configuration) anywhere along the continuum structure, as can be done in water-jet propulsion. In this article we apply the framework specifically to a tip actuated soft continuum manipulator. The proposed control scheme employs both actuator feedback and pose feedback. The actuator feedback is utilized to both regulate the follower load and to compensate for non-linearities of the actuation system that can introduce kinematic model error. Pose feedback is required to maintain accurate path following. Experimental results demonstrate successful path following with the closed-loop control scheme, with significant performance improvements gained through the use of sensor feedback when compared with the open-loop case.

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Qi, Fei, Feng Ju, Dong Ming Bai, and Bai Chen. "Kinematics optimization and static analysis of a modular continuum robot used for minimally invasive surgery." Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine 232, no. 2 (December 11, 2017): 135–48. http://dx.doi.org/10.1177/0954411917747008.

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For the outstanding compliance and dexterity of continuum robot, it is increasingly used in minimally invasive surgery. The wide workspace, high dexterity and strong payload capacity are essential to the continuum robot. In this article, we investigate the workspace of a cable-driven continuum robot that we proposed. The influence of section number on the workspace is discussed when robot is operated in narrow environment. Meanwhile, the structural parameters of this continuum robot are optimized to achieve better kinematic performance. Moreover, an indicator based on the dexterous solid angle for evaluating the dexterity of robot is introduced and the distal end dexterity is compared for the three-section continuum robot with different range of variables. Results imply that the wider range of variables achieve the better dexterity. Finally, the static model of robot based on the principle of virtual work is derived to analyze the relationship between the bending shape deformation and the driven force. The simulations and experiments for plane and spatial motions are conducted to validate the feasibility of model, respectively. Results of this article can contribute to the real-time control and movement and can be a design reference for cable-driven continuum robot.

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Konow, Nicolai, and Thomas J. Roberts. "The series elastic shock absorber: tendon elasticity modulates energy dissipation by muscle during burst deceleration." Proceedings of the Royal Society B: Biological Sciences 282, no. 1804 (April 7, 2015): 20142800. http://dx.doi.org/10.1098/rspb.2014.2800.

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During downhill running, manoeuvring, negotiation of obstacles and landings from a jump, mechanical energy is dissipated via active lengthening of limb muscles. Tendon compliance provides a ‘shock-absorber’ mechanism that rapidly absorbs mechanical energy and releases it more slowly as the recoil of the tendon does work to stretch muscle fascicles. By lowering the rate of muscular energy dissipation, tendon compliance likely reduces the risk of muscle injury that can result from rapid and forceful muscle lengthening. Here, we examine how muscle–tendon mechanics are modulated in response to changes in demand for energy dissipation. We measured lateral gastrocnemius (LG) muscle activity, force and fascicle length, as well as leg joint kinematics and ground-reaction force, as turkeys performed drop-landings from three heights (0.5–1.5 m centre-of-mass elevation). Negative work by the LG muscle–tendon unit during landing increased with drop height, mainly owing to greater muscle recruitment and force as drop height increased. Although muscle strain did not increase with landing height, ankle flexion increased owing to increased tendon strain at higher muscle forces. Measurements of the length–tension relationship of the muscle indicated that the muscle reached peak force at shorter and likely safer operating lengths as drop height increased. Our results indicate that tendon compliance is important to the modulation of energy dissipation by active muscle with changes in demand and may provide a mechanism for rapid adjustment of function during deceleration tasks of unpredictable intensity.

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Journal articles on the topic 'Kinematics and compliance'

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