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1
WANG, KE-YI, WEN-YAN ZHAO, ZHUANG HAN, WAN-LI WANG e XIAO-QIANG TANG. "REHABILITATIVE STRATEGIES OF MULTIPLE LOWER LIMBS TRAINING MODELS". Journal of Mechanics in Medicine and Biology 18, n. 08 (dicembre 2018): 1840030. http://dx.doi.org/10.1142/s0219519418400304.
Testo completoAbstract (sommario):
According to the combination of lower limbs rehabilitative robot (LLRR), the effect of multi-point and single point driving form on muscle force and joint torque is explored, and the rehabilitation effect of the training mode of the active–passive rehabilitation training is studied. The musculoskeletal model of lower limbs is established based on the physiological structure of human lower limbs. And considering the position of the attachment points of each muscle, the mechanical properties of muscles and applied moment of joints can be obtained under different rehabilitative training strategies by inverse dynamic analysis. The rehabilitation training strategies of flexion–extension and abduction and adduction movements are put forward according to the movement of lower limbs. And using the wire-driven rehabilitation robot as the driving device of the rehabilitation training, the robot is used to simulate the motor function of patients’ lower limbs by modifying the parameters of muscle which can affect the resistance moment of joint motion, then the effects of driving form and the active–passive training mode are analyzed. The results show that single point driving form is better than multi-point on muscle strength and joint strength training; the rehabilitation training strategies of flexion–extension and abduction–adduction movements show different superiority.
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Zhang, Leiyu, Jianfeng Li, Junhui Liu, Peng Su e Chunzhao Zhang. "Design and Kinematic Analysis of Co-Exoskeleton with Passive Translational Joints for Upper-Limb Rehabilitation". International Journal of Humanoid Robotics 15, n. 05 (27 settembre 2018): 1850020. http://dx.doi.org/10.1142/s0219843618500202.
Testo completoAbstract (sommario):
A key approach for reducing motor impairment and regaining independence after spinal cord injuries or strokes is frequent and repetitive functional training. A compatible exoskeleton (Co-Exoskeleton) with four passive translational joints is proposed for the upper-limb rehabilitation. There are only three passive translational joints to track and assist movements of the glenohumeral joint (GH), where two joints are installed horizontally at the front section and another one at the connecting interface of the upper arm. This type of configuration can lower the influences of gravities of the exoskeleton device and upper extremity. The kinematic models of GH and the corresponding human–machine system are established using the analytical method. A numerical simulation of the kinematic models is implemented with MATLAB to emphatically analyze the kinematic characteristics of passive joints and the center of Co-Exoskeleton. The translational displacements of passive joints in four elevation planes are obtained during the elevating process. The results of the kinematic analysis show that the passive joints have similar motion characteristics under different elevation planes. Additionally, the position changes of GH in three directions can be tracked and compensated approximately. Co-Exoskeleton has an especially good compensation effect for the vertical movement of GH. The compensation effect and kinematic models are verified by using the elevating experiments. This research provides theoretical and methodological guidance for the ergonomic design and kinematic analysis of the rehabilitation exoskeleton.
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CORAZZA, FEDERICO, VINCENZO PARENTI-CASTELLI, RITA STAGNI, ANGELO CAPPELLO, JOHN J. O'CONNOR e ALBERTO LEARDINI. "BIOMECHANICS OF THE INTACT AND REPLACED HUMAN ANKLE JOINT". Journal of Mechanics in Medicine and Biology 06, n. 01 (marzo 2006): 39–46. http://dx.doi.org/10.1142/s0219519406001819.
Testo completoAbstract (sommario):
The main objective of the study was to develop advanced biomechanical models of the intact human ankle complex. It was also aimed at designing a total ankle replacement which would better reproduce the physiological function of the joint. Passive flexion was analyzed in a number of lower-leg preparations with stereophotogrammetry and radiostereometry. The articular surfaces and fibres within the calcaneofibular and tibiocalcaneal ligaments were observed to prescribe the changing positions of bones, ligaments and instantaneous axis of rotation. Joint motion included rolling as well as sliding. Computer-based models elucidated this kinematics at the intact joint, and how changing positions of the centre of rotation and muscle lines of action affect lever arm length at different flexion angles. The mechanical response of the joint to anterior drawer and talar tilt tests was explained in terms of fibre recruitment. The experimental evidence and the geometrical models gave the basis for the design of a novel ankle replacement. A three-component, convex-tibia prosthesis was developed with articular surface shapes that are compatible with the geometry of the ligaments. The proposed prosthesis based on ligament/shape compatibility is showing encouraging results in initial implantation.
4
Di Gregorio, Raffaele, e Vincenzo Parenti-Castelli. "A Spatial Mechanism With Higher Pairs for Modelling the Human Knee Joint". Journal of Biomechanical Engineering 125, n. 2 (1 aprile 2003): 232–37. http://dx.doi.org/10.1115/1.1559895.
Testo completoAbstract (sommario):
By generalizing a previous model proposed in the literature, a new spatial kinematic model of the knee joint passive motion is presented. The model is based on an equivalent spatial parallel mechanism which relies upon the assumption that fibers within the anterior cruciate ligament (ACL), the medial collateral ligament (MCL) and the posterior cruciate ligament (PCL) can be considered as isometric during the knee flexion in passive motion (virtually unloaded motion). The articular surfaces of femoral and tibial condyles are modelled as 3-D surfaces of general shapes. In particular, the paper presents the closure equations of the new mechanism both for surfaces represented by means of scalar equations that have the Cartesian coordinates of the points of the surface as variables and for surfaces represented in parametric form. An example of simulation is presented in the case both femoral condyles are modelled as ellipsoidal surfaces and tibial condyles as spherical surfaces. The results of the simulation are compared to those of the previous models and to measurements. The comparison confirms the expectation that a better approximation of the tibiofemoral condyle surfaces leads to a more accurate model of the knee passive motion.
5
Kositsky, Adam, David J. Saxby, Kim J. Lesch, Rod S. Barrett, Heikki Kröger, Olli Lahtinen, Laura E. Diamond, Rami K. Korhonen e Lauri Stenroth. "In vivo assessment of the passive stretching response of the bicompartmental human semitendinosus muscle using shear-wave elastography". Journal of Applied Physiology 132, n. 2 (1 febbraio 2022): 438–47. http://dx.doi.org/10.1152/japplphysiol.00473.2021.
Testo completoAbstract (sommario):
We conducted an elastography-based investigation of the passive stretching response of the proximal and distal compartments of the human semitendinosus muscle and found no difference in shear modulus-joint angle curves between compartments. We also found that common musculoskeletal models tend to misestimate semitendinosus slack angle, most likely due to typical model assumptions. These results provide an important step toward a better understanding of semitendinosus passive muscle mechanics and improving computational estimates of muscle force.
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Di Gregorio, R., V. Parenti-Castelli, J. J. O’Connor e A. Leardini. "Mathematical models of passive motion at the human ankle joint by equivalent spatial parallel mechanisms". Medical & Biological Engineering & Computing 45, n. 3 (13 febbraio 2007): 305–13. http://dx.doi.org/10.1007/s11517-007-0160-7.
Testo completo
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Zhou, Congcong, Zhao Yang, Kaitai Li e Xuesong Ye. "Research and Development of Ankle–Foot Orthoses: A Review". Sensors 22, n. 17 (1 settembre 2022): 6596. http://dx.doi.org/10.3390/s22176596.
Testo completoAbstract (sommario):
The ankle joint is one of the important joints of the human body to maintain the ability to walk. Diseases such as stroke and ankle osteoarthritis could weaken the body’s ability to control joints, causing people’s gait to be out of balance. Ankle–foot orthoses can assist users with neuro/muscular or ankle injuries to restore their natural gait. Currently, passive ankle–foot orthoses are mostly designed to fix the ankle joint and provide support for walking. With the development of materials, sensing, and control science, semi-active orthoses that release mechanical energy to assist walking when needed and can store the energy generated by body movement in elastic units, as well as active ankle–foot orthoses that use external energy to transmit enhanced torque to the ankle, have received increasing attention. This article reviews the development process of ankle–foot orthoses and proposes that the integration of new ankle–foot orthoses with rehabilitation technologies such as monitoring or myoelectric stimulation will play an important role in reducing the walking energy consumption of patients in the study of human-in-the-loop models and promoting neuro/muscular rehabilitation.
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Engin, Ali Erkan, e Shuenn-Muh Chen. "Kinematic and Passive Resistive Properties of Human Elbow Complex". Journal of Biomechanical Engineering 109, n. 4 (1 novembre 1987): 318–23. http://dx.doi.org/10.1115/1.3138687.
Testo completoAbstract (sommario):
In recent years, owing to their versatility and reduced cost of operation, multisegmented mathematical models of the total human body have gained increased attention in gross biodynamic motion studies. This, in turn, has stimulated the need for a proper biomechanical data base for the major human articulating joints. The lack of such a database for the humero-elbow complex is the impetus for this study. The total angular range of motion permitted by the complex and the passive resistive properties beyond the full elbow extension were studied. Results obtained on ten normal male subjects were utilized to establish a statistical data base for the humero-elbow complex. Results are also expressed in functional expansion form suitable for incorporation into the existing multisegmented models.
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Hughes, J. A. E., P. Maiolino e F. Iida. "An anthropomorphic soft skeleton hand exploiting conditional models for piano playing". Science Robotics 3, n. 25 (19 dicembre 2018): eaau3098. http://dx.doi.org/10.1126/scirobotics.aau3098.
Testo completoAbstract (sommario):
The development of robotic manipulators and hands that show dexterity, adaptability, and subtle behavior comparable to human hands is an unsolved research challenge. In this article, we considered the passive dynamics of mechanically complex systems, such as a skeleton hand, as an approach to improving adaptability, dexterity, and richness of behavioral diversity of such robotic manipulators. With the use of state-of-the-art multimaterial three-dimensional printing technologies, it is possible to design and construct complex passive structures, namely, a complex anthropomorphic skeleton hand that shows anisotropic mechanical stiffness. We introduce a concept, termed the “conditional model,” that exploits the anisotropic stiffness of complex soft-rigid hybrid systems. In this approach, the physical configuration, environment conditions, and conditional actuation (applied actuation) resulted in an observable conditional model, allowing joint actuation through passivity-based dynamic interactions. The conditional model approach allowed the physical configuration and actuation to be altered, enabling a single skeleton hand to perform three different phrases of piano music with varying styles and forms and facilitating improved dynamic behaviors and interactions with the piano over those achievable with a rigid end effector.
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Li, Na, Ziyan Hao, Haiyong Jiang e Bo Yu. "Positioning Control of a Human-Machine Cooperative Grafting Manipulator for Unstructured Environments". Transactions of the ASABE 63, n. 5 (2020): 1477–91. http://dx.doi.org/10.13031/trans.13817.
Testo completoAbstract (sommario):
HighlightsPositioning of a human-machine cooperative grafting manipulator for high-crown grafting of fruit trees is analyzed.PID control based on feedforward compensation of a dynamic model can realize high-precision position control of the braking process in unstructured agricultural environments.A manipulator based on the proposed control method can realize accurate position control and time-varying operating forces and can provide energy savings to meet the requirements of field operations.Abstract. Crown grafting of fruit trees has the disadvantages of high labor intensity and reduced graft survival. Therefore, a human-machine cooperative manipulator that relies on passive joint braking was designed to realize position control. The manipulator can replace manual operations to solve the problem of different positions in the grafting process and provide positioning and force support for canopy grafting. This study determined that the working space of the manipulator can cover the canopy area of fruit trees. Dynamic equations were established for motion simulation and feedforward compensation control of the manipulator. According to the dynamic model, the joint braking process was simulated. The simulation results showed that the joint braking torque needs to be dynamically controlled to ensure positioning accuracy of the manipulator. A process of passive joint braking was designed based on the proposed ideal braking curve. By comparing the position control accuracy of independent proportional integral derivative (PID) control, dynamic model feedforward compensation control, and PID control based on feedforward compensation of the dynamic model in simulations, it was determined that PID control based on feedforward compensation of the dynamic model was suitable for application in the braking torque control system. Finally, prototype tests showed that PID control based on feedforward compensation of the dynamic model can realize high-precision joint braking and position control of the manipulator. The positioning error was less than 5%, and the maximum vibration acceleration amplitude was reduced by 26.7% to 68.5%. The control system of the manipulator, using PID control based on feedforward compensation of the dynamic model, can provide adaptability for unstructured environments and reduce power consumption for application in field operations. Keywords: Controls, Dynamics, Grafting, Positioning, Simulation models, Unstructured agricultural environment.
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Almuhammadi, Wafaa Salem, Emmanuel Agu, Jean King e Patricia Franklin. "OA-Pain-Sense: Machine Learning Prediction of Hip and Knee Osteoarthritis Pain from IMU Data". Informatics 9, n. 4 (6 dicembre 2022): 97. http://dx.doi.org/10.3390/informatics9040097.
Testo completoAbstract (sommario):
Joint pain is a prominent symptom of Hip and Knee Osteoarthritis (OA), impairing patients’ movements and affecting the joint mechanics of walking. Self-report questionnaires are currently the gold standard for Hip OA and Knee OA pain assessment, presenting several problems, including the fact that older individuals often fail to provide accurate self-pain reports. Passive methods to assess pain are desirable. This study aims to explore the feasibility of OA-Pain-Sense, a passive, automatic Machine Learning-based approach that predicts patients’ self-reported pain levels using SpatioTemporal Gait features extracted from the accelerometer signal gathered from an anterior-posterior wearable sensor. To mitigate inter-subject variability, we investigated two types of data rescaling: subject-level and dataset-level. We explored six different binary machine learning classification models for discriminating pain in patients with Hip OA or Knee OA from healthy controls. In rigorous evaluation, OA-Pain-Sense achieved an average accuracy of 86.79% using the Decision Tree and 83.57% using Support Vector Machine classifiers for distinguishing Hip OA and Knee OA patients from healthy subjects, respectively. Our results demonstrate that OA-Pain-Sense is feasible, paving the way for the development of a pain assessment algorithm that can support clinical decision-making and be used on any wearable device, such as smartphones.
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Remus, Robin, Andreas Lipphaus, Marc Neumann e Beate Bender. "Calibration and validation of a novel hybrid model of the lumbosacral spine in ArtiSynth–The passive structures". PLOS ONE 16, n. 4 (26 aprile 2021): e0250456. http://dx.doi.org/10.1371/journal.pone.0250456.
Testo completoAbstract (sommario):
In computational biomechanics, two separate types of models have been used predominantly to enhance the understanding of the mechanisms of action of the lumbosacral spine (LSS): Finite element (FE) and musculoskeletal multibody (MB) models. To combine advantages of both models, hybrid FE-MB models are an increasingly used alternative. The aim of this paper is to develop, calibrate, and validate a novel passive hybrid FE-MB open-access simulation model of a ligamentous LSS using ArtiSynth. Based on anatomical data from the Male Visible Human Project, the LSS model is constructed from the L1-S1 rigid vertebrae interconnected with hyperelastic fiber-reinforced FE intervertebral discs, ligaments, and facet joints. A mesh convergence study, sensitivity analyses, and systematic calibration were conducted with the hybrid functional spinal unit (FSU) L4/5. The predicted mechanical responses of the FSU L4/5, the lumbar spine (L1-L5), and the LSS were validated against literature data from in vivo and in vitro measurements and in silico models. Spinal mechanical responses considered when loaded with pure moments and combined loading modes were total and intervertebral range of motions, instantaneous axes and centers of rotation, facet joint contact forces, intradiscal pressures, disc bulges, and stiffnesses. Undesirable correlations with the FE mesh were minimized, the number of crisscrossed collagen fiber rings was reduced to five, and the individual influences of specific anatomical structures were adjusted to in vitro range of motions. Including intervertebral motion couplings for axial rotation and nonlinear stiffening under increasing axial compression, the predicted kinematic and structural mechanics responses were consistent with the comparative data. The results demonstrate that the hybrid simulation model is robust and efficient in reproducing valid mechanical responses to provide a starting point for upcoming optimizations and extensions, such as with active skeletal muscles.
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Wünschel, Markus, Ulf Leichtle, JiaHsuan Lo, Nikolaus Wülker e Otto Müller. "Differences in tibiofemoral kinematics between the unloaded robotic passive path and a weightbearing knee simulator". Orthopedic Reviews 3, n. 2 (3 gennaio 2012): 2. http://dx.doi.org/10.4081/or.2012.e2.
Testo completoAbstract (sommario):
Cadaveric <em>in vitro</em> studies are essential to test hypotheses concerning surgical manipulations in the same individual. Robotic technologies as well as different knee-models have been developed to get an in-depth comprehension of knee joint kinematics. The purpose of this study was to compare utilization of these different established principles. Ten human cadaveric knee specimens were used to measure the kinematics during a weight-bearing flexion in a 6-degrees-of-freedom knee simulator. While flexing the knee, joint quadriceps muscle forces were dynamically simulated to reach a vertical ground reaction force of 100N. Fourteen knee specimens were mounted in 6-degrees-of-freedom robotic manipulator with a universal force sensor. The unloaded flexing motion of each specimen was measured by finding positions for each degree of flexion where all forces are minimal (passive path). The kinematic data of the kneesimulator and the robot concerning <em>internal-external</em> rotation, <em>anterior-posterior</em> translation, <em>varus-valgus</em> motion, and <em>medial-lateral </em>translation was examined. For all investigated degrees of freedom the kinematics of the robotic passive path differed from the loaded kinematics in the knee simulator. Simulated bodyweight as well as the examination method used has a substantial influence on joint kinematics during flexion which has to be considered when interpreting biomechanical studies as well as clinical tests.
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Scherb, David, Patrick Steck, Harald Völkl, Sandro Wartzack e Jörg Miehling. "A NEW METHOD FOR PASSIVE ANKLE FOOT ORTHOSIS DESIGN – INTEGRATION OF MUSCULOSKELETAL AND FINITE ELEMENT SIMULATION". Proceedings of the Design Society 3 (19 giugno 2023): 333–42. http://dx.doi.org/10.1017/pds.2023.34.
Testo completoAbstract (sommario):
AbstractMotor disorders are diseases affecting the muscle function of the human body. A frequently occurring motor disorder affects the lower leg muscles resulting in a pathological gait called foot drop. Patients have a higher risk of stumbling and falling. The most common treatment is the use of a passive ankle-foot-orthosis (AFO). However, the compensation of foot drop is only limited due to the non possible support of all rotational directions of the ankle joint. Therefore, a newly developed concept for a passive AFO is currently in work. To ensure a best possible treatment of the patient, the provided support by the AFO and required support by the patient have to be in accordance. Thus, in this contribution a method is presented that integrates model order reduced finite element analysis for computing the provided support of the AFO and musculoskeletal human models for representing the patients' gait behaviour. With the method, the design of the force generating structures of the AFO can be realized regarding the patients' requirements. The presented method is further evaluated with a specific use case. The main focus lies here in the principal functionality of the method and the provision of valid results.
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Dean, J. C., e A. D. Kuo. "Elastic coupling of limb joints enables faster bipedal walking". Journal of The Royal Society Interface 6, n. 35 (28 ottobre 2008): 561–73. http://dx.doi.org/10.1098/rsif.2008.0415.
Testo completoAbstract (sommario):
The passive dynamics of bipedal limbs alone are sufficient to produce a walking motion, without need for control. Humans augment these dynamics with muscles, actively coordinated to produce stable and economical walking. Present robots using passive dynamics walk much slower, perhaps because they lack elastic muscles that couple the joints. Elastic properties are well known to enhance running gaits, but their effect on walking has yet to be explored. Here we use a computational model of dynamic walking to show that elastic joint coupling can help to coordinate faster walking. In walking powered by trailing leg push-off, the model's speed is normally limited by a swing leg that moves too slowly to avoid stumbling. A uni-articular spring about the knee allows faster but uneconomical walking. A combination of uni-articular hip and knee springs can speed the legs for improved speed and economy, but not without the swing foot scuffing the ground. Bi-articular springs coupling the hips and knees can yield high economy and good ground clearance similar to humans. An important parameter is the knee-to-hip moment arm that greatly affects the existence and stability of gaits, and when selected appropriately can allow for a wide range of speeds. Elastic joint coupling may contribute to the economy and stability of human gait.
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Kerimoğlu, Deniz, Ömer Morgül e Uluç Saranli. "Stability and control of planar compass gait walking with series-elastic ankle actuation". Transactions of the Institute of Measurement and Control 39, n. 3 (1 ottobre 2016): 312–23. http://dx.doi.org/10.1177/0142331216663823.
Testo completoAbstract (sommario):
Passive dynamic walking models are capable of capturing basic properties of walking behaviours and can generate stable human-like walking without any actuation on inclined surfaces. The passive compass gait model is among the simplest of such models, consisting of a planar point mass and two stick legs. A number of different actuation methods have been proposed both for this model and its more complex extensions to eliminate the need for a sloped ground, balancing collision losses using gravitational potential energy. In this study, we introduce and investigate an extended model with series-elastic actuation at the ankle towards a similar goal, realizing stable walking on level ground. Our model seeks to capture the basic structure of how humans utilize toe push-off prior to leg liftoff, and is intended to eventually be used for controlling the ankle joint in a lower-body robotic orthosis. We derive hybrid equations of motion for this model, and show numerically through Poincaré analysis that it can achieve asymptotically stable walking on level ground for certain choices of system parameters. We then study the bifurcation regimes of period doubling with this model, leading up to chaotic walking patterns. Finally, we show that feedback control on the initial extension of the series ankle spring can be used to improve and extend system stability.
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Belli, Italo, Sagar Joshi, J. Micah Prendergast, Irene Beck, Cosimo Della Santina, Luka Peternel e Ajay Seth. "Does enforcing glenohumeral joint stability matter? A new rapid muscle redundancy solver highlights the importance of non-superficial shoulder muscles". PLOS ONE 18, n. 11 (30 novembre 2023): e0295003. http://dx.doi.org/10.1371/journal.pone.0295003.
Testo completoAbstract (sommario):
The complexity of the human shoulder girdle enables the large mobility of the upper extremity, but also introduces instability of the glenohumeral (GH) joint. Shoulder movements are generated by coordinating large superficial and deeper stabilizing muscles spanning numerous degrees-of-freedom. How shoulder muscles are coordinated to stabilize the movement of the GH joint remains widely unknown. Musculoskeletal simulations are powerful tools to gain insights into the actions of individual muscles and particularly of those that are difficult to measure. In this study, we analyze how enforcement of GH joint stability in a musculoskeletal model affects the estimates of individual muscle activity during shoulder movements. To estimate both muscle activity and GH stability from recorded shoulder movements, we developed a Rapid Muscle Redundancy (RMR) solver to include constraints on joint reaction forces (JRFs) from a musculoskeletal model. The RMR solver yields muscle activations and joint forces by minimizing the weighted sum of squared-activations, while matching experimental motion. We implemented three new features: first, computed muscle forces include active and passive fiber contributions; second, muscle activation rates are enforced to be physiological, and third, JRFs are efficiently formulated as linear functions of activations. Muscle activity from the RMR solver without GH stability was not different from the computed muscle control (CMC) algorithm and electromyography of superficial muscles. The efficiency of the solver enabled us to test over 3600 trials sampled within the uncertainty of the experimental movements to test the differences in muscle activity with and without GH joint stability enforced. We found that enforcing GH stability significantly increases the estimated activity of the rotator cuff muscles but not of most superficial muscles. Therefore, a comparison of shoulder model muscle activity to EMG measurements of superficial muscles alone is insufficient to validate the activity of rotator cuff muscles estimated from musculoskeletal models.
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Gottlieb, G. L., e G. C. Agarwal. "Compliance of single joints: elastic and plastic characteristics". Journal of Neurophysiology 59, n. 3 (1 marzo 1988): 937–51. http://dx.doi.org/10.1152/jn.1988.59.3.937.
Testo completoAbstract (sommario):
1. Step changes in torque were applied to the elbow or ankle joint of normal human subjects who exerted constant levels of effort. They were instructed to not react to the torque but to allow their limbs to move to a new equilibrium position. In this experimental paradigm, the joint may be characterized by a nonlinear compliant element. The aim of this study was to characterize the elastic properties of the compliant element. 2. Joint elasticity is described by an S-shaped relation between torque and angle (a "compliant characteristic curve"). The stiffness of a joint is greatest for small perturbations and decreases as the size of the perturbation is increased whether the limb is loaded or unloaded from its initial equilibrium. 3. The S shape of the compliant characteristic curve is relatively constant when measured at different initial joint angles from the same initial joint torque. 4. Higher levels of initial muscle torque increase the steepness of the compliant characteristic curve. 5. All changes in initial joint torque and angle preserve the S shape. The inflection point of the characteristic curve is always at the initial equilibrium angle and torque. This shifting of the inflection point of the torque-angle relation implies a fundamental plasticity in joint compliance. The elastic component is not invariant but changes with the joint's initial equilibrium state. 6. Changes in muscle tension and length that result from a perturbation are accompanied by changes in muscle activation. The relationship between perturbation torque and mean equilibrium EMG is similar to that found for voluntary isometric contraction. It is not possible to conclude what proportion of the late EMG response to perturbation is mediated by segmental reflex mechanisms. 7. At the levels of torque used here, changes in joint stiffness are highly correlated with changes in tonic contraction of the muscle opposing the load. This change in stiffness is not the result of antagonist coactivation, which was minimal. 8. The compliant characteristic curves of elbow and ankle are qualitatively similar. The principal difference is due to the greater passive stiffness of the ankle. 9. Our findings are inconsistent with aspects of the theory of invariant characteristics or with models of movement and load compensation that postulate a control scheme based only on the setting of muscle and reflex equilibrium points. The data are also incompatible with models that only control the elastic stiffness of the muscle.
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Jackson, Rachel W., e Steven H. Collins. "An experimental comparison of the relative benefits of work and torque assistance in ankle exoskeletons". Journal of Applied Physiology 119, n. 5 (1 settembre 2015): 541–57. http://dx.doi.org/10.1152/japplphysiol.01133.2014.
Testo completoAbstract (sommario):
Techniques proposed for assisting locomotion with exoskeletons have often included a combination of active work input and passive torque support, but the physiological effects of different assistance techniques remain unclear. We performed an experiment to study the independent effects of net exoskeleton work and average exoskeleton torque on human locomotion. Subjects wore a unilateral ankle exoskeleton and walked on a treadmill at 1.25 m·s−1 while net exoskeleton work rate was systematically varied from −0.054 to 0.25 J·kg−1·s−1, with constant (0.12 N·m·kg−1) average exoskeleton torque, and while average exoskeleton torque was systematically varied from approximately zero to 0.18 N·m·kg−1, with approximately zero net exoskeleton work. We measured metabolic rate, center-of-mass mechanics, joint mechanics, and muscle activity. Both techniques reduced effort-related measures at the assisted ankle, but this form of work input reduced metabolic cost (−17% with maximum net work input) while this form of torque support increased metabolic cost (+13% with maximum average torque). Disparate effects on metabolic rate seem to be due to cascading effects on whole body coordination, particularly related to assisted ankle muscle dynamics and the effects of trailing ankle behavior on leading leg mechanics during double support. It would be difficult to predict these results using simple walking models without muscles or musculoskeletal models that assume fixed kinematics or kinetics. Data from this experiment can be used to improve predictive models of human neuromuscular adaptation and guide the design of assistive devices.
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Sultan, Nadia, Asif Mahmood Mughal, Muhammad Najam ul Islam e Fahad Mumtaz Malik. "High-gain observer-based nonlinear control scheme for biomechanical sit to stand movement in the presence of sensory feedback delays". PLOS ONE 16, n. 8 (12 agosto 2021): e0256049. http://dx.doi.org/10.1371/journal.pone.0256049.
Testo completoAbstract (sommario):
Sit-to-stand movement (STS) is a mundane activity, controlled by the central-nervous-system (CNS) via a complex neurophysiological mechanism that involves coordination of limbs for successful execution. Detailed analysis and accurate simulations of STS task have significant importance in clinical intervention, rehabilitation process, and better design for assistive devices. The CNS controls STS motion by taking inputs from proprioceptors. These input signals suffer delay in transmission to CNS making movement control and coordination more complex which may lead to larger body exertion or instability. This paper deals with the problem of STS movement execution in the presence of proprioceptive feedback delays in joint position and velocity. We present a high-gain observer (HGO) based feedback linearization control technique to mimic the CNS in controlling the STS transfer. The HGO estimates immeasurable delayed states to generate input signals for feedback. The feedback linearization output control law generates the passive torques at joints to execute the STS movement. The H2 dynamic controller calculates the optimal linear gains by using physiological variables. The whole scheme is simulated in MATLAB/Simulink. The simulations illustrate physiologically improved results. The ankle, knee, and hip joint position profiles show a high correlation of 0.91, 0.97, 0.80 with the experimentally generated reference profiles. The faster observer dynamics and global boundness of controller result in compensation of delays. The low error and high correlation of simulation results demonstrate (1) the reliability and effectiveness of the proposed scheme for customization of human models and (2) highlight the fact that for detailed analysis and accurate simulations of STS movement the modeling scheme must consider nonlinearities of the system.
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WISSE, MARTIJN. "THREE ADDITIONS TO PASSIVE DYNAMIC WALKING: ACTUATION, AN UPPER BODY, AND 3D STABILITY". International Journal of Humanoid Robotics 02, n. 04 (dicembre 2005): 459–78. http://dx.doi.org/10.1142/s0219843605000570.
Testo completoAbstract (sommario):
One of the main challenges in the design of human-like walking robots (useful for service or entertainment applications as well as the study of human locomotion) is to obtain dynamic locomotion, as opposed to the static form of locomotion demonstrated by most of the current prototypes. A promising concept is the idea of passive dynamic walking; even completely unactuated and uncontrolled mechanisms can perform a stable gait when walking down a shallow slope. This concept enables the construction of dynamically walking prototypes that are simpler yet more natural in their motions than the static bipeds. This paper presents three additions to the concept of passive dynamic walking. First, hip actuation is added to increase the fore-aft stability and to provide power to the system, removing the need for a downhill floor. Second, a bisecting hip mechanism is introduced to allow the addition of a passive upper body without compromising the simplicity, efficiency and naturalness of the concept of passive dynamic walking. Third, skateboard-like ankle joints are implemented to provide 3D stability. These ankles couple the unstable sideways lean motion to yaw (steering), a kinematic coupling which provides sideways stability when walking with sufficient forward velocity. The three additions are investigated both with elementary simulation models and with prototype experiments. All three prototypes demonstrate an uncannily natural and stable gait while requiring only two foot switches and three on/off actuators.
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Jochumsen, Mads, Sylvain Cremoux, Lucien Robinault, Jimmy Lauber, Juan Arceo, Muhammad Navid, Rasmus Nedergaard, Usman Rashid, Heidi Haavik e Imran Niazi. "Investigation of Optimal Afferent Feedback Modality for Inducing Neural Plasticity with A Self-Paced Brain-Computer Interface". Sensors 18, n. 11 (3 novembre 2018): 3761. http://dx.doi.org/10.3390/s18113761.
Testo completoAbstract (sommario):
Brain-computer interfaces (BCIs) can be used to induce neural plasticity in the human nervous system by pairing motor cortical activity with relevant afferent feedback, which can be used in neurorehabilitation. The aim of this study was to identify the optimal type or combination of afferent feedback modalities to increase cortical excitability in a BCI training intervention. In three experimental sessions, 12 healthy participants imagined a dorsiflexion that was decoded by a BCI which activated relevant afferent feedback: (1) electrical nerve stimulation (ES) (peroneal nerve—innervating tibialis anterior), (2) passive movement (PM) of the ankle joint, or (3) combined electrical stimulation and passive movement (Comb). The cortical excitability was assessed with transcranial magnetic stimulation determining motor evoked potentials (MEPs) in tibialis anterior before, immediately after and 30 min after the BCI training. Linear mixed regression models were used to assess the changes in MEPs. The three interventions led to a significant (p < 0.05) increase in MEP amplitudes immediately and 30 min after the training. The effect sizes of Comb paradigm were larger than ES and PM, although, these differences were not statistically significant (p > 0.05). These results indicate that the timing of movement imagery and afferent feedback is the main determinant of induced cortical plasticity whereas the specific type of feedback has a moderate impact. These findings can be important for the translation of such a BCI protocol to the clinical practice where by combining the BCI with the already available equipment cortical plasticity can be effectively induced. The findings in the current study need to be validated in stroke populations.
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Wang, Su, Sarah Kurth, Christof Burger, Dieter C. Wirtz, Frank A. Schildberg e Robert Ossendorff. "TNFα-Related Chondrocyte Inflammation Models: A Systematic Review". International Journal of Molecular Sciences 25, n. 19 (8 ottobre 2024): 10805. http://dx.doi.org/10.3390/ijms251910805.
Testo completoAbstract (sommario):
Tumor necrosis factor alpha (TNFα), as a key pro-inflammatory cytokine, plays a central role in joint diseases. In recent years, numerous models of TNFα-induced cartilage inflammation have been developed. However, due to the significant differences between these models and the lack of consensus in their construction, it becomes difficult to compare the results of different studies. Therefore, we summarized and compared these models based on important parameters for model construction, such as cell source, cytokine concentration, stimulation time, mechanical stimulation, and more. We attempted to analyze the advantages and disadvantages of each model and provide a compilation of the analytical methods used in previous studies. Currently, TNFα chondrocyte inflammation models can be categorized into four main types: monolayer-based, construct-based, explant-based TNFα chondrocyte inflammation models, and miscellaneous TNFα chondrocyte inflammation models. The most commonly used models were the monolayer-based TNFα chondrocyte inflammation models (42.86% of cases), with 10 ng/mL TNFα being the most frequently used concentration. The most frequently used chondrocyte cell passage is passage 1 (50%). Human tissues were most frequently used in experiments (51.43%). Only five articles included models with mechanical stimulations. We observed variations in design conditions between different models. This systematic review provides the essential experimental characteristics of the available chondrocyte inflammation models with TNFα, and it provides a platform for better comparison between existing and new studies in this field. It is essential to perform further experiments to standardize each model and to find the most appropriate experimental parameters.
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Che, Junjie, Yang Pan, Wei Yan e Jiexian Yu. "Leg Configuration Analysis and Prototype Design of Biped Robot Based on Spring Mass Model". Actuators 11, n. 3 (2 marzo 2022): 75. http://dx.doi.org/10.3390/act11030075.
Testo completoAbstract (sommario):
The leg structure with high dynamic stability can make the bionic biped robot have the inherent conditions to perform elastic and highly dynamic motion. Compared with the quadruped robot, the leg structure of the biped robot is more complex and has more degrees of freedom. This also complicates kinematic and dynamic modeling. In this paper, the kinematics model of a bionic biped robot is established. The leg configuration of the robot is a series parallel hybrid mechanism with five active joints and six passive joints. The mechanism is a spring mass model that interacts organically with the environment and mimics the characteristics of human walking well. By analyzing the topological configuration of leg mechanism, we use the screw theory to establish the forward and inverse kinematics models. Then, we build the prototype, and use a step gait to test the model and prototype. The research of this paper has obvious application significance for the design and iteration of biped robot prototype.
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Geng, Tao, Bernd Porr e Florentin Wörgötter. "A Reflexive Neural Network for Dynamic Biped Walking Control". Neural Computation 18, n. 5 (maggio 2006): 1156–96. http://dx.doi.org/10.1162/neco.2006.18.5.1156.
Testo completoAbstract (sommario):
Biped walking remains a difficult problem, and robot models can greatly facilitate our understanding of the underlying biomechanical principles as well as their neuronal control. The goal of this study is to specifically demonstrate that stable biped walking can be achieved by combining the physical properties of the walking robot with a small, reflex-based neuronal network governed mainly by local sensor signals. Building on earlier work (Taga, 1995; Cruse, Kindermann, Schumm, Dean, & Schmitz, 1998), this study shows that human-like gaits emerge without specific position or trajectory control and that the walker is able to compensate small disturbances through its own dynamical properties. The reflexive controller used here has the following characteristics, which are different from earlier approaches: (1) Control is mainly local. Hence, it uses only two signals (anterior extreme angle and ground contact), which operate at the interjoint level. All other signals operate only at single joints. (2) Neither position control nor trajectory tracking control is used. Instead, the approximate nature of the local reflexes on each joint allows the robot mechanics itself (e.g., its passive dynamics) to contribute substantially to the overall gait trajectory computation. (3) The motor control scheme used in the local reflexes of our robot is more straightforward and has more biological plausibility than that of other robots, because the outputs of the motor neurons in our reflexive controller are directly driving the motors of the joints rather than working as references for position or velocity control. As a consequence, the neural controller and the robot mechanics are closely coupled as a neuromechanical system, and this study emphasizes that dynamically stable biped walking gaits emerge from the coupling between neural computation and physical computation. This is demonstrated by different walking experiments using a real robot as well as by a Poincaré map analysis applied on a model of the robot in order to assess its stability.
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Rico-Garcia, Mateo, Juan Botero-Valencia e Ruber Hernández-García. "Vertical Jump Data from Inertial and Optical Motion Tracking Systems". Data 7, n. 8 (17 agosto 2022): 116. http://dx.doi.org/10.3390/data7080116.
Testo completoAbstract (sommario):
Motion capture (MOCAP) is a widely used technique to record human, animal, and object movement for various applications such as animation, biomechanical assessment, and control systems. Different systems have been proposed based on diverse technologies, such as visible light cameras, infrared cameras with passive or active markers, inertial systems, or goniometer-based systems. Each system has pros and cons that make it usable in different scenarios. This paper presents a dataset that combines Optical Motion and Inertial Systems, capturing a well-known sports movement as the vertical jump. As a reference system, the optical motion capture consists of six Flex 3 Optitrack cameras with 100 FPS. On the other hand, we developed an inertial system consisting of seven custom-made devices based on the IMU MPU-9250, which includes a three-axis magnetometer, accelerometer and gyroscope, and an embedded Digital Motion Processor (DMP) attached to a microcontroller mounted on a Teensy 3.2 with an ARM Cortex-M4 processor with wireless operation using Bluetooth. The purpose of taking IMU data with a low-cost and customized system is the deployment of applications that can be performed with similar hardware and can be adjusted to different areas. The developed measurement system is flexible, and the acquisition format and enclosure can be customized. The proposed dataset comprises eight jumps recorded from four healthy humans using both systems. Experimental results on the dataset show two usage examples for measuring joint angles and COM position. The proposed dataset is publicly available online and can be used in comparative algorithms, biomechanical studies, skeleton reconstruction, sensor fusion techniques, or machine learning models.
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Choi, Wan-Su, Jeong-In Yang, Wihak Kim, Hyo-Eun Kim, Seul-Ki Kim, Yoonkyung Won, Young-Ok Son, Churl-Hong Chun e Jang-Soo Chun. "Critical role for arginase II in osteoarthritis pathogenesis". Annals of the Rheumatic Diseases 78, n. 3 (4 gennaio 2019): 421–28. http://dx.doi.org/10.1136/annrheumdis-2018-214282.
Testo completoAbstract (sommario):
ObjectiveOsteoarthritis (OA) appears to be associated with various metabolic disorders, but the potential contribution of amino acid metabolism to OA pathogenesis has not been clearly elucidated. Here, we explored whether alterations in the amino acid metabolism of chondrocytes could regulate OA pathogenesis.MethodsExpression profiles of amino acid metabolism-regulating genes in primary-culture passage 0 mouse chondrocytes were examined by microarray analysis, and selected genes were further characterised in mouse OA chondrocytes and OA cartilage of human and mouse models. Experimental OA in mice was induced by destabilisation of the medial meniscus (DMM) or intra-articular (IA) injection of adenoviruses expressing catabolic regulators. The functional consequences of arginase II (Arg-II) were examined in Arg2−/− mice and those subjected to IA injection of an adenovirus encoding Arg-II (Ad-Arg-II).ResultsThe gene encoding Arg-II, an arginine-metabolising enzyme, was specifically upregulated in chondrocytes under various pathological conditions and in OA cartilage from human patients with OA and various mouse models. Adenovirus-mediated overexpression of Arg-II in mouse joint tissues caused OA pathogenesis, whereas genetic ablation of Arg2 in mice (Arg2−/−) abolished all manifestations of DMM-induced OA. Mechanistically, Arg-II appears to cause OA cartilage destruction at least partly by upregulating the expression of matrix-degrading enzymes (matrix metalloproteinase 3 [MMP3] and MMP13) in chondrocytes via the nuclear factor (NF)-κB pathway.ConclusionsOur results indicate that Arg-II is a crucial regulator of OA pathogenesis in mice. Although chondrocytes of human and mouse do not identically, but similarly, respond to Arg-II, our results suggest that Arg-II could be a therapeutic target of OA pathogenesis.
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Zong, Zhixian, Xiaoting Zhang, Zhengmeng Yang, Weihao Yuan, Jianping Huang, Weiping Lin, Ting Chen et al. "Rejuvenated ageing mesenchymal stem cells by stepwise preconditioning ameliorates surgery-induced osteoarthritis in rabbits". Bone & Joint Research 10, n. 1 (1 gennaio 2021): 10–21. http://dx.doi.org/10.1302/2046-3758.101.bjr-2020-0249.r1.
Testo completoAbstract (sommario):
Aims Ageing-related incompetence becomes a major hurdle for the clinical translation of adult stem cells in the treatment of osteoarthritis (OA). This study aims to investigate the effect of stepwise preconditioning on cellular behaviours in human mesenchymal stem cells (hMSCs) from ageing patients, and to verify their therapeutic effect in an OA animal model. Methods Mesenchymal stem cells (MSCs) were isolated from ageing patients and preconditioned with chondrogenic differentiation medium, followed by normal growth medium. Cellular assays including Bromodeoxyuridine / 5-bromo-2'-deoxyuridine (BrdU), quantitative polymerase chain reaction (q-PCR), β-Gal, Rosette forming, and histological staining were compared in the manipulated human mesenchymal stem cells (hM-MSCs) and their controls. The anterior cruciate ligament transection (ACLT) rabbit models were locally injected with two millions, four millions, or eight millions of hM-MSCs or phosphate-buffered saline (PBS). Osteoarthritis Research Society International (OARSI) scoring was performed to measure the pathological changes in the affected joints after staining. Micro-CT analysis was conducted to determine the microstructural changes in subchondral bone. Results Stepwise preconditioning approach significantly enhanced the proliferation and chondrogenic potential of ageing hMSCs at early passage. Interestingly, remarkably lower immunogenicity and senescence was also found in hM-MSCs. Data from animal studies showed cartilage damage was retarded and subchondral bone remodelling was prevented by the treatment of preconditioned MSCs. The therapeutic effect depended on the number of cells applied to animals, with the best effect observed when treated with eight millions of hM-MSCs. Conclusion This study demonstrated a reliable and feasible stepwise preconditioning strategy to improve the safety and efficacy of ageing MSCs for the prevention of OA development. Cite this article: Bone Joint Res 2021;10(1):10–21.
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Rusnak, Janice M., Pamela J. Glass, Scott C. Weaver, Carol L. Sabourin, Andrew M. Glenn, William Klimstra, Christopher S. Badorrek, Farooq Nasar e Lucy A. Ward. "Approach to Strain Selection and the Propagation of Viral Stocks for Venezuelan Equine Encephalitis Virus Vaccine Efficacy Testing under the Animal Rule". Viruses 11, n. 9 (31 agosto 2019): 807. http://dx.doi.org/10.3390/v11090807.
Testo completoAbstract (sommario):
Licensure of a vaccine to protect against aerosolized Venezuelan equine encephalitis virus (VEEV) requires use of the U.S. Food and Drug Administration (FDA) Animal Rule to assess vaccine efficacy as human studies are not feasible or ethical. An approach to selecting VEEV challenge strains for use under the Animal Rule was developed, taking into account Department of Defense (DOD) vaccine requirements, FDA Animal Rule guidelines, strain availability, and lessons learned from the generation of filovirus challenge agents within the Filovirus Animal Nonclinical Group (FANG). Initial down-selection to VEEV IAB and IC epizootic varieties was based on the DOD objective for vaccine protection in a bioterrorism event. The subsequent down-selection of VEEV IAB and IC isolates was based on isolate availability, origin, virulence, culture and animal passage history, known disease progression in animal models, relevancy to human disease, and ability to generate sufficient challenge material. Methods for the propagation of viral stocks (use of uncloned (wild-type), plaque-cloned, versus cDNA-cloned virus) to minimize variability in the potency of the resulting challenge materials were also reviewed. The presented processes for VEEV strain selection and the propagation of viral stocks may serve as a template for animal model development product testing under the Animal Rule to other viral vaccine programs. This manuscript is based on the culmination of work presented at the “Alphavirus Workshop” organized and hosted by the Joint Vaccine Acquisition Program (JVAP) on 15 December 2014 at Fort Detrick, Maryland, USA.
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Gasparutto, Xavier, Eric Jacquelin e Raphael Dumas. "Contribution of passive actions to the lower limb joint moments and powers during gait: A comparison of models". Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine 232, n. 8 (13 luglio 2018): 768–78. http://dx.doi.org/10.1177/0954411918785661.
Testo completoAbstract (sommario):
The lower limb passive actions representing the actions of all the passive periarticular structures have been shown to have a significant contribution to the power generation and absorption during gait. However, the respective magnitude of its different components was not established, although models of ligament moment were implemented in some musculoskeletal models. These ligament moments have shown to have an influence on the musculo-tendon forces and contact forces but the models used were never specifically evaluated, that is, compared to the passive and net joint moments. Two models of passive joint moments and three models of ligament moments were selected from the literature. Ten subjects (23–29 years old, 79.8 ± 9.5 kg, 1.85 ± 0.06 m) participated in the study. Each subject performed three gait cycles in a gait laboratory to acquire the kinematics and ground reaction forces and to compute the ligament, passive and net moments of the right lower limb joints. The contributions of the passive joint moments to the net joint moments were in accordance with the literature, although time shifts appeared for peaks in the hip and knee powers. Two of the models of ligament moments seemed, in fact, to represent the passive joint moments as their contributions were very similar while the third model of ligament moments seemed to represent only penalty-based joint limits. As a conclusion, this study showed that the models of ligament moments existing in the literature do not seem reliable. This study also demonstrated that the use of non-subject-specific models of the passive joint moments could be a valid approach for healthy subjects.
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Zaier, Riadh, e A. Al-Yahmedi. "Design of Biomechanical Legs with a Passive Toe Joint for Enhanced Human-like Walking". Journal of Engineering Research [TJER] 14, n. 2 (30 giugno 2017): 166. http://dx.doi.org/10.24200/tjer.vol14iss2pp166-181.
Testo completoAbstract (sommario):
This paper presents the design procedure of a biomechanical leg, with a passive toe joint, which is capable of mimicking the human walking. This leg has to provide the major features of human gait in the motion trajectories of the hip, knee, ankle, and toe joints. Focus was given to the approach of designing the passive toe joint of the biomechanical leg in its role and effectiveness in performing human like motion. This study was inspired by experimental and theoretical studies in the fields of biomechanics and robotics. Very light materials were mainly used in the design process. Aluminum and carbon fiber parts were selected to design the proposed structure of this biomechanical leg, which is to be manufactured in the Mechanical Lab of the Sultan Qaboos University (SQU). The capabilities of the designed leg to perform the normal human walking are presented. This study provides a noteworthy and unique design for the passive toe joint, represented by a mass-spring damper system, using torsion springs in the foot segment. The working principle and characteristics of the passive toe joint are discussed. Four-designed cases, with different design parameters, for the passives toe joint system are presented to address the significant role that the passive toe joint plays in human-like motion. The dynamic motion that is used to conduct this comparison was the first stage of the stance motion. The advantages of the presence of the passive toe joint in gait, and its effect on reducing the energy consumption by the other actuated joints are presented and a comparison between the four-designed cases is discussed.
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Li, Shuyang, Paolo Dario e Zhibin Song. "Prediction of Passive Torque on Human Shoulder Joint Based on BPANN". Applied Bionics and Biomechanics 2020 (28 agosto 2020): 1–10. http://dx.doi.org/10.1155/2020/8839791.
Testo completoAbstract (sommario):
In upper limb rehabilitation training by exploiting robotic devices, the qualitative or quantitative assessment of human active effort is conducive to altering the robot control parameters to offer the patients appropriate assistance, which is considered an effective rehabilitation strategy termed as assist-as-needed. Since active effort of a patient is changeable for the conscious or unconscious behavior, it is considered to be more feasible to determine the distributions of the passive resistance of the patient’s joints versus the joint angle in advance, which can be adopted to assess the active behavior of patients combined with the measurement of robotic sensors. However, the overintensive measurements can impose a burden on patients. Accordingly, a prediction method of shoulder joint passive torque based on a Backpropagation neural network (BPANN) was proposed in the present study to expand the passive torque distribution of the shoulder joint of a patient with less measurement data. The experiments recruiting three adult male subjects were conducted, and the results revealed that the BPANN exhibits high prediction accurate for each direction shoulder passive torque. The results revealed that the BPANN can learn the nonlinear relationship between the passive torque and the position of the shoulder joint and can make an accurate prediction without the need to build a force distribution function in advance, making it possible to draw up an assist-as-needed strategy with high accuracy while reducing the measurement burden of patients and physiotherapists.
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TANIGUCHI, Shohei, Ryuta OZAWA, Norimitsu SAKAGAMI e Sadao KAWAMURA. "Joint Torque Decomposition of Human Body in Passive Motion". Transactions of the Society of Instrument and Control Engineers 41, n. 9 (2005): 763–71. http://dx.doi.org/10.9746/sicetr1965.41.763.
Testo completo
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Blankevoort, L., R. Huiskes e A. de Lange. "The reproducibility of passive human knee-joint motion characteristics". Journal of Biomechanics 18, n. 7 (gennaio 1985): 529–30. http://dx.doi.org/10.1016/0021-9290(85)90726-2.
Testo completo
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Marko Gjinko, Juliana. "The 2008 Law “On Gender Equality in Society” and Some of its Effects on Equal Representation." Academicus International Scientific Journal 29 (gennaio 2024): 119–33. http://dx.doi.org/10.7336/academicus.2024.29.07.
Testo completoAbstract (sommario):
Since the fall of their socialist centralized systems, the countries of Central and Eastern Europe have experienced considerable changes to their socioeconomic policies. The Republic of Albania has encountered several noteworthy challenges since 1992, and initially, eradicating gender inequality was not given much emphasis. Gender equality is an essential element that needs to be incorporated into the legal frameworks of all candidate countries aspiring to join the EU, in addition to being a fundamental right and a shared vision of EU institutions. In developing nations, social exclusion can be either active or passive. Because females are excluded from many facets of society, such as the workforce, education, access to the legal system, the realization of their property rights, and so forth, women’s demands and interests are frequently disregarded. Following the UN Convention on the Elimination of All Forms of Discrimination Against Women (CEDAW), the Republic of Albania has developed a number of laws, policies, and action plans pertaining to gender equality, in addition to measures addressing issues such as human trafficking, domestic abuse, closing the representational gap in politics and the economy, and other matters. This essay looks at Albania’s methodology for evaluating European standards and, where necessary, adapts them to regional political and cultural norms. Ensuring that the body of legislation is in accord with the culture in which it functions is a better strategy to enforce laws than merely making models, rules, and regulations. This is a comprehensive effort to assess and contrast specific in pursuing full EU integration. This is an overall attempt to evaluate and compare some of the strategies and actions Albanian representatives and society have taken to address the gender factor in the democratization process and institution-building while pursuing full EU integration.
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Qin, Ling, e Bo Lei. "Distributed Multiagent for NAO Robot Joint Position Control Based on Echo State Network". Mathematical Problems in Engineering 2015 (2015): 1–7. http://dx.doi.org/10.1155/2015/945493.
Testo completoAbstract (sommario):
Based on echo state networks, the joints position control of NAO robot is studied in this paper. The process to control the robot position can be divided into two phases. The senor parameters are released during the first phase. Depending on the dynamic coupling effect between the angle acceleration of passive joint and the torque of active joint, passive joint can be controlled indirectly to the desired position along the desired trajectory. The ESN control rules during the first phase are described and ESN controller is designed to control the motion of passive joint. The brake is locked during the second phase; then active joint is controlled to the desired position. The experimental control system based on PMAC controller is designed and developed. Finally, the joint position control of the NAO robot is achieved successfully by experiments. Echo state networks utilized incremental updates driven by new sensor readings and massive short memory with history inputs; thus varying communication rates can help imitate human upper limb motion based on wearable sensors to obtain human joint angles.
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Schliemann, Benedikt, Michael Raschke, Philipp Michel, Lukas Heilmann, Felix Dyrna, Julia Sußiek, Andre Frank, Jan Katthagen e Jens Wermers. "It’s more than size that matters: The role of glenoid concavity in shoulder instability with anterior bone loss". Orthopaedic Journal of Sports Medicine 9, n. 7_suppl4 (1 luglio 2021): 2325967121S0019. http://dx.doi.org/10.1177/2325967121s00198.
Testo completoAbstract (sommario):
Objectives: The mechanism of concavity-compression is known to be a key factor for glenohumeral stability in the mid-range of motion. This stabilizing effect is impaired by traumatic bone loss at the anterior glenoid rim. Currently, a critical threshold based on the defect size is used as a decisive criterion for surgical treatment. However, recent studies using finite element method (FEM)-simulations indicate that glenoid concavity is essential for an assessment of remaining glenohumeral stability. To date, there is no biomechanical investigation involving glenoid concavity in combination with defect size. In this biomechanical study we focused on the interdependence between glenoid concavity, defect size and glenohumeral stability. We hypothesized that glenohumeral stability is mainly dependent on concavity and that the initial concavity affects the loss of stability caused by bony defects at the anterior glenoid rim. Methods: A 6-degree-of-freedom industrial robot was utilized to determine the stability of 17 human cadaveric glenoids, depending on osteochondral concavity and anterior defect size. Load-and-shift tests were performed with artificial humeri equipped with a best-fit implant while joint positions and loads were captured. The Stability Ratio (SR), defined as the maximum tolerated anterior force related to a constant compression force, was determined for a compression of 50 N. In addition to a translation in 3 o’clock direction relative to a right scapula, a passive path dislocation was performed using compensatory translations to minimize superoinferior forces occurring during anterior translation. Defects were created in 2 mm steps parallel to the long axis of the glenoid until dislocation occurred self-acting and a 3D measuring arm was used for morphometric measurements as depicted in Figure 1. For statistical analysis, linear mixed-effects models were established to exploit the impacts of fixed effects (defect size and concavity gradient) as well as random effects (repeated measures and friction) on the SR. The influence of defect size on SR was analyzed for a translation in 3 o’clock by classifying the specimens into three groups of low (<25 %, n = 6), medium (25-35 %, n = 6) and high (>35 %, n = 5) initial concavity gradients. In addition, the Bony Shoulder Stability Ratio (BSSR), a characteristic based on glenoid depth and radius, was determined to evaluate its correlation with the measured SR and to find a suitable characteristic for the assessment of SR independent of defect size. Results: For a translation in 3 o’clock, the linear model resulted in an intercept of 7.13 ± 1.57 (95 % CI [4.01, 10.24]), representing the SR for zero defect size and concavity gradient. The linear coefficient for the predictor concavity gradient averaged 1.05 ± 0.05 (95 % CI [0.96, 1.14]) corresponding to a rise of SR by 1.05 % with each percentage of concavity gradient. Both coefficients were significantly different from zero with p<0.001. The defect size had only an indirect impact on SR, as the linear coefficient of 0.03 ± 0.04 (95 % CI [-0.10, 0.05]) differed insignificantly from zero (p = 0.53). The entire model featured a determination coefficient of R² = 0.98 and a mean squared error (MSE) of 4.22 %. This relationship is diagramed in Figure 2. Using the defect size as an exclusive predictor reduced R² to 0.87 and increased MSE up to 25.72 %. The passive path translation started on average in 2:16 o’clock for the intact glenoid and shifted to 3:06 o’clock with increasing defect size. Though the model indicated a significant impact of concavity gradient as well as defect size on SR (p<0.001), the influence of defect size ( 0.18 ± 0.03, 95 % CI [ 0.24, -0.11])) was significantly smaller than the effect of concavity gradient (0.97 ± 0.04, 95 % CI [0.88, 1.05]). However, the linear model for the passive path resulted in R² = 0.97 and MSE = 5.5 %. Separate linear models for the three groups of low, medium and high initial concavity gradients indicated significant differences in the slope coefficients (low: -0.55 ± 0.05 (95 % CI [ 0.65, 0.45]); medium: 0.78 ± 0.04 (95 % CI [-0.87, -0.70]); high: -1.25 ± 0.06 (95 % CI [ 1.36, -1.13])). This represented a significant impact of the initial glenoid concavity on the loss of SR per defect size. Raw data points as well as the linear approximations are shown in Figure 3. The linear model with the BSSR as a predictor for the measured SR is depicted in Figure 4 indicating a highly linear correlation with R² = 0.98 and MSE = 3.4 % for the translation in 3 o’clock. Conclusions: The SR is significantly dependent on the glenoid concavity whereas the defect size has a negligible indirect impact, provided that both predictors are included in a linear model. Due to constitutional different glenoid shapes, the loss of SR per defect size is significantly dependent on the initial concavity gradient. However, the BSSR has proven to be a reliable predictor of glenohumeral stability independent of defect size. These findings demonstrate that concavity is a crucial factor in estimating residual SR and substantiate that defect size as the only critical threshold is an inappropriate decisive criterion in the treatment of shoulder instabilities with anterior glenoid bone loss.
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McDaniel, John, Stephen J. Ives e Russell S. Richardson. "Human muscle length-dependent changes in blood flow". Journal of Applied Physiology 112, n. 4 (15 febbraio 2012): 560–65. http://dx.doi.org/10.1152/japplphysiol.01223.2011.
Testo completoAbstract (sommario):
Although a multitude of factors that influence skeletal muscle blood flow have been extensively investigated, the influence of muscle length on limb blood flow has received little attention. Thus the purpose of this investigation was to determine if cyclic changes in muscle length influence resting blood flow. Nine healthy men (28 ± 4 yr of age) underwent a passive knee extension protocol during which the subjects' knee joint was passively extended and flexed through 100–180° knee joint angle at a rate of 1 cycle per 30 s. Femoral blood flow, cardiac output (CO), heart rate (HR), stroke volume (SV), and mean arterial pressure (MAP) were continuously recorded during the entire protocol. These measurements revealed that slow passive changes in knee joint angle did not have a significant influence on HR, SV, MAP, or CO; however, net femoral blood flow demonstrated a curvilinear increase with knee joint angle ( r2 = 0.98) such that blood flow increased by ∼90% (125 ml/min) across the 80° range of motion. This net change in blood flow was due to a constant antegrade blood flow across knee joint angle and negative relationship between retrograde blood flow and knee joint angle ( r2 = 0.98). Thus, despite the absence of central hemodynamic changes and local metabolic factors, blood flow to the leg was altered by changes in muscle length. Therefore, when designing research protocols, researchers need to be cognizant of the fact that joint angle, and ultimately muscle length, influence limb blood flow.
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Liu, Ying-Chi, e Yukio Takeda. "Kineto-Static Analysis of a Wrist Rehabilitation Robot with Compliance and Passive Joints for Joint Misalignment Compensation". Machines 8, n. 2 (2 maggio 2020): 23. http://dx.doi.org/10.3390/machines8020023.
Testo completoAbstract (sommario):
In this paper, we present a kineto-static analysis on a wrist rehabilitation robot to compensate for joint misalignment between human and robot joints. Since joint misalignment has proved to generate user–device interaction forces, which reduce the comfort and safety of the wearable devices and limit the user’s willingness to use it. The use of compliance and the addition of passive joints for joint misalignment compensation are discussed. In order to study the effect of the initial offset, we find that the initial offset in the direction perpendicular to the forearm causes a larger unwanted force. In addition, the use of the softest compliance can minimize unwanted force by 38% compared to the case without compliance. Furthermore, the effect of the addition of passive joints to the exoskeleton is investigated. From the analysis results, the soft part of the human being is regarded as a passive joint with the ability to compensate for joint misalignment. Moreover, the influence of the soft characteristics of human limbs should be considered when designing a wearable robot. This soft property, causing the movement of the braces, results in reducing the angular range of the wrist. Through the analysis results, we provide effective ideas for joint misalignment compensation to fulfill a comfortable and safer robot design.
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Spazzin, Aloísio Oro, Guilherme Elias Pessanha Henriques, Mauro Antônio de Arruda Nóbilo, Rafael Leonardo Xediek Consani, Lourenço Correr-Sobrinho e Marcelo Ferraz Mesquita. "Influence of Prosthetic Screw Material on Joint Stability in Passive and Non-Passive Implant-Supported Dentures". Open Dentistry Journal 3, n. 1 (30 dicembre 2009): 245–49. http://dx.doi.org/10.2174/1874210600903010245.
Testo completoAbstract (sommario):
Objectives: This study evaluated the influence of prosthetic screw material on joint stability in implantsupported dentures at two levels of fit. Methods: Ten mandibular implant-supported dentures were fabricated. Twenty cast models were fabricated using these dentures. Four groups (n=10) were tested, according to the vertical fit of the dentures [passive and non-passive] and prosthetic screw materials [titanium (Ti) or gold (Au) alloy]. The one-screw test was performed to quantify the vertical misfits using an optic microscope. The loosening torque for the prosthetic screws was measured 24 hours after the tightening torque (10 Ncm) using a digital torque meter. Data were analyzed by two-way ANOVA and Tukey’s test (α=0.05). Results: Overall, dentures with passive fit and Ti screws resulted in significantly higher loosening torque of the prosthetic screws (p<0.05). No significant interaction was found between fit level and screw material (p=0.199). The prosthetic screw material and fit of implant-supported dentures have an influence on screw joint stability. Ti screws presented higher joint stability than Au screws and minimum of misfit should be found clinically to improve the mechanical behavior of the screw joint.
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Køster, D., J. H. Egedal, M. Hvid, M. R. Jakobsen, U. Müller-Ladner, B. Deleuran, T. W. Kragstrup, E. Neumann e M. A. Nielsen. "AB0100 PHENOTYPIC AND FUNCTIONAL CHARACTERIZATION OF SYNOVIAL FLUID-DERIVED FIBROBLAST-LIKE SYNOVIOCYTES IN RHEUMATOID ARTHRITIS". Annals of the Rheumatic Diseases 79, Suppl 1 (giugno 2020): 1349.1–1349. http://dx.doi.org/10.1136/annrheumdis-2020-eular.3884.
Testo completoAbstract (sommario):
Background:Fibroblast-like synoviocytes (FLS) are central cellular components in persistent inflammatory joint diseases such as rheumatoid arthritis (RA). Pathological subsets of FLS have been identified from synovial tissue. However, the synovial tissue obtained from arthroplasty procedures is acquired at late disease stages and the cellular yield obtained from synovial tissue biopsies is fairly low. Collectively, challenging the robustness of human RAin vivoandin vitromodels. FLS obtained from the synovial fluid (SF-FLS) are proposed as an alternative source of FLS, but a detailed phenotypical and functional characterization of FLS subsets from the synovial fluid has not been performed.Objectives:The aim of this study was to determine the phenotypical and functional characteristics of synovial fluid-derived fibroblast-like synoviocytes in rheumatoid arthritis.Methods:In the present study, paired peripheral blood mononuclear cells (PBMC) and SF-FLS from patients with RA were obtained (n=7). FLS were isolated from the synovial fluid by a strict trypsinization protocol1and their cellular characteristics and functionality were evaluated at passage 4. Monocultures (SF-FLS) and autologous co-cultures (SF-FLS and PBMC) were established from five patients with RA and subsequently evaluated by flow cytometry, Western blotting and multiplex immunoassays. Human cartilage-sponges (n=3) with SF-FLS and without SF-FLS (n=3) were co-implanted subcutaneously in SCID mice (n=15), mice with only cell-free human cartilage-sponges were used as controls (n=12). After 45 days, the implants were evaluated using stained sections to determine the SF-FLS invasion score based on perichondrocytic cartilage degradation. Data are expressed as median (25-75 percentile). P-values <0.05 were considered statistically significant.Results:The homogeneous subpopulations of FLS, isolated from the synovial fluid, were negative for CD34 and CD45 [98.9%, (97.5-99.7]) and positive for Thy-1 and PDPN [94.6%, (79.9-97.4]). Without stimulation, RA SF-FLS showed high and comparable levels of NFκB related pathway proteins and secreted multiple pro-inflammatory cytokines and chemokines dominated by IL-6 [2648 pg/mL, (1327-6116)] and MCP-1 [2458 pg/mL, (692-8719)]. SF-FLS increased their ICAM-1 and HLA-DR expression after encountering autologous PBMCs (p<0.01), (p<0.05). Further, SF-FLS and PBMC interacted synergistically in a co-culture model of RA and significantly increasing the secretion of several cytokines (IL-1β, IL-2, IL-6, (p<0.01)) and a chemokine (MCP-1, (p<0.01)). The invasion score of the human SF-FLSin vivowas at primary site, [1.6, (1.3-1.7)] and contralateral implantation site [1.5, (1.1-2.2)]. The invasion score of the human SF-FLS-containing implants both at primary and contralateral site were significantly higher compared with cartilage-sponges evaluated from SF-FLS-free control mice (p<0001).Conclusion:This phenotypical and functional characterization of SF-FLS, acquired and activated at the site of pathology, lays a foundation for establishingin vivoandin vitroFLS models. These FLS models will be beneficial in our understanding of the role of this cellular subset in arthritis and for characterization of drugs specifically targeting this pathological RA FLS subset.References:[1]Nielsen M. A. et al. Responses to Cytokine Inhibitors Associated with Cellular Composition in Models of Immune-Mediated Inflammatory Arthritis. ACR Open Rheumatology, 2(1):3-10.http://doi.org/10.1002/acr2.11094Disclosure of Interests:Ditte Køster: None declared, Johanne Hovgaard Egedal: None declared, Malene Hvid: None declared, Martin Roelsgaard Jakobsen: None declared, Ulf Müller-Ladner Speakers bureau: Biogen, Bent Deleuran: None declared, Tue Wenzel Kragstrup Shareholder of: iBio Tech ApS, Consultant of: Bristol-Myers Squibb, Speakers bureau: TWK has engaged in educational activities talking about immunology in rheumatic diseases receiving speaking fees from Pfizer, Bristol-Myers Squibb, Eli Lilly, Novartis, and UCB., Elena Neumann: None declared, Morten Aagaard Nielsen: None declared
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Galley, Alexandre, Emma Donnelly, Ilya Borukhov, Brent Lanting e Ryan Willing. "Muscle-Driven Total Knee Replacement Stability with Virtual Ligaments". Bioengineering 12, n. 2 (25 gennaio 2025): 112. https://doi.org/10.3390/bioengineering12020112.
Testo completoAbstract (sommario):
Knee joint stability comprises passive (ligaments), active (muscles), and static (articular congruency) contributors. The stability of total knee replacement (TKR) implants can be assessed pre-clinically using joint motion simulators. However, contemporary testing methods with these platforms do not accurately reproduce the biomechanical contributions of passive stabilizers, active stabilizers, or both. A key component of joint stability is therefore missing from laxity tests. A recently developed muscle actuator system (MAS) pairs the quadriceps-driven motion capabilities of an Oxford knee simulator with the prescribed displacements and laxity testing methods of a VIVO robotic knee testing system, which also includes virtual ligament capabilities. Using a TKR-embedded non-cadaveric joint analogue, TKR with two different virtual ligament models were compared to TKR with no active ligaments. Laxity limits were then obtained for both developed models using the conventional style of laxity testing (the VIVO’s force/displacement control) and compared with results obtained under similar conditions with the MAS (gravity-dependent muscle control). Differences in joint control methods identified the need for muscle forces providing active joint stability, while differences in the effects of the virtual ligament models identified the importance of physiological representations of collateral ligaments during testing.
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Lucie, Sarah. "A Passive Performative: Alternative Models of Human Agency". Journal of Dramatic Theory and Criticism 35, n. 2 (2021): 113–16. http://dx.doi.org/10.1353/dtc.2021.0008.
Testo completo
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CHAN, CHING-CHAO, CHOU-CHING K. LIN e MING-SHAUNG JU. "ESTIMATION OF ANKLE JOINT ANGLE FROM PERONEAL AND TIBIAL ELECTRONEUROGRAMS — A MUSCLE SPINDLE MODEL APPROACH". Journal of Mechanics in Medicine and Biology 12, n. 04 (settembre 2012): 1250080. http://dx.doi.org/10.1142/s0219519412005046.
Testo completoAbstract (sommario):
This study develops a method for estimating the angle of a passively stretched ankle joint from electroneurograms (ENGs) based on structural muscle spindle models of the tibial and peroneal nerves. Passive ramp-and-hold and alternating stretches of the ankle joint are performed on an anesthetized rabbit. Two cuff electrodes are employed to measure the ENGs of peroneal and tibial nerves simultaneously. From the two ENG signals and the joint angle trajectory, two intrafusal muscle fiber models are constructed and their inverse models are derived. The results of the two models are combined to generate the final angle estimate. An optimization method, called sequential quadratic programming, is employed to find the model parameters that minimize the squared errors between the ankle angles predicted by the model and the measured ankle angles. The performance of the proposed approach is compared with those of an adaptive neuro-fuzzy inference system and an artificial neural network model. The results reveal that the proposed model has the best performance in estimating the ankle joint angle in large-range movements and the smallest tracing error. The proposed method effectively estimates the passive ankle joint angle using the inverse physiological model of an intrafusal muscle fiber.
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Wong, Kayleigh, Guy Trudel e Odette Laneuville. "Noninflammatory Joint Contractures Arising from Immobility: Animal Models to Future Treatments". BioMed Research International 2015 (2015): 1–6. http://dx.doi.org/10.1155/2015/848290.
Testo completoAbstract (sommario):
Joint contractures, defined as the limitation in the passive range of motion of a mobile joint, can be classified as noninflammatory diseases of the musculoskeletal system. The pathophysiology is not well understood; limited information is available on causal factors, progression, the pathophysiology involved, and prediction of response to treatment. The clinical heterogeneity of joint contractures combined with the heterogeneous contribution of joint connective tissues to joint mobility presents challenges to the study of joint contractures. Furthermore, contractures are often a symptom of a wide variety of heterogeneous disorders that are in many cases multifactorial. Extended immobility has been identified as a causal factor and evidence is provided from both experimental and epidemiology studies. Of interest is the involvement of the joint capsule in the pathophysiology of joint contractures and lack of response to remobilization. While molecular pathways involved in the development of joint contractures are being investigated, current treatments focus on physiotherapy, which is ineffective on irreversible contractures. Future treatments may include early diagnosis and prevention.
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McFaull, Steve, e Mario Lamontagne. "The passive elastic moment about the in vivo human knee joint". Journal of Biomechanics 27, n. 6 (gennaio 1994): 809. http://dx.doi.org/10.1016/0021-9290(94)91356-0.
Testo completo
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Hu, Jie, Yuantao Zhuang, Yudi Zhu, Qiaoling Meng e Hongliu Yu. "Intelligent Parametric Adaptive Hybrid Active–Passive Training Control Method for Rehabilitation Robot". Machines 10, n. 7 (6 luglio 2022): 545. http://dx.doi.org/10.3390/machines10070545.
Testo completoAbstract (sommario):
Rehabilitation robots facilitate patients to take part in physical and occupational training. Most of the rehabilitation robots used in clinical practice adopt pure passive training or active training, which cannot sense the active participation of patients during passive training and lack adaptive dynamic adjustment of training parameters for patients. In this paper, an intelligent hybrid active–passive training control method is proposed to enhance the active participation of patients in passive training mode. Firstly, the patients’ joint mobility and maximum muscle power are modelized and calibrated. Secondly, the robot joints are actuated to train according to joint mobility and speed for two cycles. The human–machine coupled force interaction control model can recognize the patients’ active participation in the training process. Finally, the passive training joint motion speed for the next training cycle is adaptively updated by the proposed control method. The experimental results demonstrate that the control method can sense the patients’ active participation and adjust the passive training speed according to the patients’ active force interaction. In conclusion, the hybrid active–passive training control method proposed in this paper achieves the desired goal and effectively improves the patients’ rehabilitation effect.
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Kozuka, Hiroaki, Daisaku Uchijima e Hiroshi Tachiya. "Motion-Assist Arm with a Passive Joint for an Upper Limb". Journal of Robotics and Mechatronics 32, n. 1 (20 febbraio 2020): 183–98. http://dx.doi.org/10.20965/jrm.2020.p0183.
Testo completoAbstract (sommario):
This study proposes a motion-assist arm that can accurately support the positioning of a human upper limb. The motion-assist arm is a three-degree-of-freedom (DOF) planer under-actuated robotic arm with a 1-DOF passive joint that can be driven by an human. A control method for the robot arm is as follows. First, when the human moves an output point of the arm manually, the passive joint is rotated with the movement of the output point. Then, for accurate positioning of the output point on a target path, the actuated joints are controlled according to the displacement of the passive joint. Based on the above method, the human can adjust the velocity of the output point deliberately while its position is accurately corrected by the actuated joints. To confirm its effectiveness, the authors conducted tests to assist the human’s upper limb movement along straight target paths, a square path, and free curves paths such as italic letters with the proposed robot arm prototype. From the results of the tests, the authors confirmed that the proposed robot arm can accurately position the upper limb of the human on the target paths while the human intentionally moves the upper limb. It is expected that the proposed arm will be used for rehabilitation because it can aid patients to move their arms correctly. In addition, the proposed arm will enable any human to achieve complex work easily.
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Ibrahim, B. S. K. K., M. O. Tokhi, M. S. Huq, R. Jailani e S. C. Gharooni. "Fuzzy Modelling of Knee Joint with Genetic Optimization". Applied Bionics and Biomechanics 8, n. 1 (2011): 85–99. http://dx.doi.org/10.1155/2011/103031.
Testo completoAbstract (sommario):
Modelling of joint properties of lower limbs in people with spinal cord injury is significantly challenging for researchers due to the complexity of the system. The objective of this study is to develop a knee joint model capable of relating electrical parameters to dynamic joint torque as well as knee angle for functional electrical stimulation application. The joint model consists of a segmental dynamic, time-invariant passive properties and uncertain time-variant active properties. The knee joint model structure comprising optimised equations of motion and fuzzy models to represent the passive viscoelasticity and active muscle properties is formulated. The model thus formulated is optimised using genetic optimization, and validated against experimental data. The developed model can be used for simulation of joint movements as well as for control development. The results show that the model developed gives an accurate dynamic characterisation of the knee joint.
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Zhang, Leiyu, Jianfeng Li, Shuting Ji, Peng Su, Chunjing Tao e Run Ji. "Design and human–machine compatibility analysis of Co-Exos II for upper-limb rehabilitation". Assembly Automation 39, n. 4 (2 settembre 2019): 715–26. http://dx.doi.org/10.1108/aa-09-2018-0127.
Testo completoAbstract (sommario):
Purpose Upper-limb joint kinematics are highly complex and the kinematics of rehabilitation exoskeletons fail to reproduce them, resulting in hyperstaticity and human–machine incompatibility. The purpose of this paper is to design and develop a compatible exoskeleton robot (Co-Exos II) to address these problems. Design/methodology/approach The configuration synthesis of Co-Exos II is completed using advanced mechanism theory. A compatible configuration is selected and four passive joints are introduced into the connecting interfaces based on optimal configuration principles. A Co-Exos II prototype with nine degrees of freedom (DOFs) is developed and still owns a compact structure and volume. A new approach is presented to compensate the vertical glenohumeral (GH) movements. Co-Exos II and the upper arm are simplified as a guide-bar mechanism at the elevating plane. The theoretical displacements of passive joints are calculated by the kinematic model of the shoulder loop. The compatible experiments are completed to measure the kinematics of passive joints. Findings The compatible configuration of the passive joints can effectively reduce the gravity influences of the exoskeleton device and the upper extremities. The passive joints exhibit excellent compensation effect for the GH joint movements by comparing the theoretical and measured results. Passive joints can compensate for most GH movements, especially vertical movements. Originality/value Co-Exos II possesses good human–machine compatibility and wearable comfort for the affected upper limbs. The proposed compensation method is convenient to therapists and stroke patients during the rehabilitation trainings.