scholarly journals Multi-Joint Coordination of Vertical Arm Movement

2003 ◽  
Vol 1 (1) ◽  
pp. 45-56 ◽  
Author(s):  
Ajay Seth ◽  
John J. McPhee ◽  
Marcus G. Pandy
Keyword(s):  
Sagittal Plane ◽  
Model Simulation ◽  
Vertical Plane ◽  
Arm Movement ◽  
Elbow Flexion ◽  
Vertical Acceleration ◽  
Joint Movement ◽  
Vertical Movements ◽  
Joint Coordination ◽  
Muscle Torques

A model of the human arm was developed to study coordination of multi-joint movement in the vertical plane. The arm was represented as a two-segment, two-degree of freedom dynamic system with net muscle torques acting at the shoulder and elbow. Kinematic data were collected from a subject who performed unrestrained vertical movements with only the initial and final hand elevations prescribed. Movements were performed with and without a hand-held load. The method of computed torques was implemented to obtain net muscle torques, which enables position and velocity feedback to be used to estimate joint angular accelerations that produce a more stable simulation of arm movement. The model simulation was then used to calculate the contributions of the net muscle torques, gravitational torques and velocity-interaction torques to the angular accelerations of the shoulder and elbow and also to the vertical acceleration of the hand. The net muscle torques and gravity were the prime movers of the arm. The velocity-dependent effects contributed little to the dynamics of arm movement and were, in fact, insignificant when the hand was loaded. The muscles of the shoulder and elbow acted synergistically to elevate the arm in the sagittal plane. The hand was accelerated upward by the elbow first, until the point of maximum elbow flexion, after which the shoulder became the prime mover. Gravity acted consistently to accelerate the hand downward. Coordination was notably invariant to changes in external load. Some compensation for load was observed in the control, and these differences were attributed mainly to an increase in system inertia.

Cerebellar Ataxia: Torque Deficiency or Torque Mismatch Between Joints?

2000 ◽  
Vol 83 (5) ◽  
pp. 3019-3030 ◽  
Author(s):  
A. J. Bastian ◽  
K. M. Zackowski ◽  
W. T. Thach
Keyword(s):  
Cerebellar Ataxia ◽  
Shoulder Joint ◽  
Inverse Dynamics ◽  
Sagittal Plane ◽  
Elbow Flexion ◽  
Free Condition ◽  
Fixed Condition ◽  
Muscle Torques ◽  
Interaction Torques ◽  
General Inability

Prior work has shown that cerebellar subjects have difficulty adjusting for interaction torques that occur during multi-jointed movements. The purpose of this study was to determine whether this deficit is due to a general inability to generate sufficient levels of phasic torque inability or due to an inability to generate muscle torques that predict and compensate for interaction torques. A second purpose was to determine whether reducing the number of moving joints by external mechanical fixation could improve cerebellar subjects' targeted limb movements. We studied control and cerebellar subjects making elbow flexion movements to touch a target under two conditions: 1) a shoulder free condition, which required only elbow flexion, although the shoulder joint was unconstrained and 2) a shoulder fixed condition, where the shoulder joint was mechanically stabilized so it could not move. We measured joint positions of the arm in the sagittal plane and electromyograms (EMGs) of shoulder and elbow muscles. Elbow and shoulder torques were estimated using inverse dynamics equations. In the shoulder free condition, cerebellar subjects made greater endpoint errors (primarily overshoots) than did controls. Cerebellar subjects' overshoot errors were largely due to unwanted flexion at the shoulder. The excessive shoulder flexion resulted from a torque mismatch, where larger shoulder muscle torques were produced at higher rates than would be appropriate for a given elbow movement. In the shoulder fixed condition, endpoint errors of cerebellar subjects and controls were comparable. The improved accuracy of cerebellar subjects was accompanied by reduced shoulder flexor muscle activity. Most of the correct cerebellar trials in the shoulder fixed condition were movements made using only muscles that flex the elbow. Our findings suggest that cerebellar subjects' poor shoulder control is due to an inability to generate muscle torques that predict and compensate for interaction torques, and not due to a general inability to generate sufficient levels of phasic torque. In addition, reducing the number of muscles to be controlled improved cerebellar ataxia.

DESIGN OF A THRESHOLD FES CONTROL SYSTEM FOR ARM MOVEMENT

2009 ◽  
Vol 09 (04) ◽  
pp. 449-479 ◽  
Author(s):  
L. LAN ◽  
K. Y. ZHU ◽  
C. Y. WEN
Keyword(s):  
Control System ◽  
Control Strategy ◽  
Model Simulation ◽  
Arm Movement ◽  
External Perturbation ◽  
Inverse Dynamic ◽  
Threshold Control ◽  
Human Arm ◽  
Point To Point ◽  
Muscle Torques

The existing functional electrical stimulation (FES) techniques often required to solve the complex "inverse dynamic problem" to calculate the muscle torques for moving along a desired trajectory. According to the threshold control theory of voluntary motor control, a bio-mimetic threshold control strategy for the FES controller is designed and tested in the human arm movement. The arm is modeled as three segments connected by two hinges joints. The movement is driven by seven muscles and limited in the horizontal plane. All muscles are described by a modified Hill-type muscle model. Simulation results suggest that the threshold FES control system can realize point to point movement and can approximately follow the desired traces in presence of feedback delays up to 20 ms. The movement can also maintain stability under external perturbation or external load. The control system can be employed in clinical application because of the following advantages: (1) The control strategy includes some mature control techniques which had been realized in hardware. (2) Only sophisticated sensors of goniometer and the surface electrodes are needed to provide feedbacks and muscle stimulation. (3) The performance of the control system will not be critically influenced by the slight change of musculo-tendon parameters and feedback delays, and even the parameters of controller are fixed.

Modeling the resistance mechanism of passive knee joint flexion and extension for use in rehabilitation equipment

2021 ◽  
pp. 095441192199013
Author(s):  
Mansoor Amiri ◽  
Farhad Tabatabai Ghomsheh ◽  
Farshad Ghazalian
Keyword(s):  
Knee Joint ◽  
Sagittal Plane ◽  
Resistance Mechanism ◽  
Time Dependent ◽  
Coefficient Of Determination ◽  
Joint Movement ◽  
Elastic Coefficient ◽  
Knee Movement ◽  
Joint Flexion ◽  
Flexion And Extension

The purpose of this study was to model the resistance mechanism of Passive Knee Joint Flexion and Extension to create a similar torque mechanism in rehabilitation equipment. In order to better model the behavior of passive knee tissues, it is necessary to exactly calculate the two coefficients of elasticity of time-independent and time-dependent parts. Ten healthy male volunteers (mean height 176.4+/−4.59 cm) participated in this study. Passive knee joint flexion and extension occurred at velocities of 15, 45, and 120 (degree/s), and in five consecutive cycles and within the range of 0 to 100° of knee movement on the sagittal plane on Cybex isokinetic dynamometer. To ensure that the muscles were relaxed, the electrical activity of knee muscles was recorded. The elastic coefficient, (KS) increased with elevating the passive velocity in flexion and extension. The elastic coefficient, (KP) was observed to grow with the passive velocity increase. While, the viscous coefficient (C) diminished with passive velocity rise in extension and flexion. The heightened passive velocity of the motion resulted in increased hysteresis (at a rate of 42%). The desired of passive velocity is lower so that there is less energy lost and the viscoelastic resistance of the tissue in the movement decreases. The Coefficient of Determination, R2 between the model-responses and experimental curves in the extension was 0.96 < R2 < 0.99 and in flexion was 0.95 < R2 < 0.99. This modeling is capable of predicting the true performance of the components of passive knee movement and we can create a resistance mechanism in the rehabilitation equipment to perform knee joint movement. Quantitative measurements of two elastic coefficients of Time-independent and Time-dependent parts passive knee joint coefficients should be used for better accurate simulation the behavior of passive tissues in the knee which is not seen in other studies.

scholarly journals Myoelectric Control Techniques for a Rehabilitation Robot

2011 ◽  
Vol 8 (1) ◽  
pp. 21-37 ◽  
Author(s):  
Alan Smith ◽  
Edward E. Brown
Keyword(s):  
Healthy Subjects ◽  
Sagittal Plane ◽  
Robot Manipulator ◽  
Wrist Joint ◽  
Elbow Flexion ◽  
Myoelectric Control ◽  
Average Error ◽  
Rehabilitation Robot ◽  
Control Scheme ◽  
Central Cord Syndrome

This work examines two different types of myoelectric control schemes for the purpose of rehabilitation robot applications. The first is a commonly used technique based on a Gaussian classifier. It is implemented in real time for healthy subjects in addition to a subject with Central Cord Syndrome (CCS). The myoelectric control scheme is used to control three degrees of freedom (DOF) on a robot manipulator which corresponded to the robot's elbow joint, wrist joint, and gripper. The classes of motion controlled include elbow flexion and extension, wrist pronation and supination, hand grasping and releasing, and rest. Healthy subjects were able to achieve 90% accuracy. Single DOF controllers were first tested on the subject with CCS and he achieved 100%, 96%, and 85% accuracy for the elbow, gripper, and wrist controllers respectively. Secondly, he was able to control the three DOF controller at 68% accuracy. The potential applications for this scheme are rehabilitation and teleoperation. To overcome limitations in the pattern recognition based scheme, a second myoelectric control scheme is also presented which is trained using electromyographic (EMG) data derived from natural reaching motions in the sagittal plane. This second scheme is based on a time delayed neural network (TDNN) which has the ability to control multiple DOF at once. The controller tracked a subject's elbow and shoulder joints in the sagittal plane. Results showed an average error of 19° for the two joints. This myoelectric control scheme has the potential of being used in the development of exoskeleton and orthotic rehabilitation applications.

Simulated Compensatory Motion of Transradial Prostheses

2008 ◽  
Author(s):  
Derek Lura ◽  
Rajiv Dubey ◽  
Stephanie L. Carey ◽  
M. Jason Highsmith
Keyword(s):  
Range Of Motion ◽  
Shoulder Joint ◽  
Degrees Of Freedom ◽  
Biomechanical Model ◽  
Elbow Flexion ◽  
Limited Range ◽  
Joint Movement ◽  
Range Of Movement ◽  
Limited Range Of Motion ◽  
Compensatory Motion

The prostheses used by the majority of persons with hand/arm amputations today have a very limited range of motion. Transradial (below the elbow) amputees lose the three degrees of freedom provided by the wrist and forearm. Some myoeletric prostheses currently allow for forearm pronation and supination (rotation about an axis parallel to the forearm) and the operation of a powered prosthetic hand. Older body-powered prostheses, incorporating hooks and other cable driven terminal devices, have even fewer degrees of freedom. In order to perform activities of daily living (ADL), a person with amputation(s) must use a greater than normal range of movement from other body joints to compensate for the loss of movement caused by the amputation. By studying the compensatory motion of prosthetic users we can understand the mechanics of how they adapt to the loss of range of motion in a given limb for select tasks. The purpose of this study is to create a biomechanical model that can predict the compensatory motion using given subject data. The simulation can then be used to select the best prosthesis for a given user, or to design prostheses that are more effective at selected tasks, once enough data has been analyzed. Joint locations necessary to accomplish the task with a given configuration are calculated by the simulation for a set of prostheses and tasks. The simulation contains a set of prosthetic configurations that are represented by parameters that consist of the degrees of freedom provided by the selected prosthesis. The simulation also contains a set of task information that includes joint constraints, and trajectories which the hand or prosthesis follows to perform the task. The simulation allows for movement in the wrist and forearm, which is dependent on the prosthetic configuration, elbow flexion, three degrees of rotation at the shoulder joint, movement of the shoulder joint about the sternoclavicular joint, and translation and rotation of the torso. All joints have definable restrictions determined by the prosthesis, and task.

Effects of Inactivation of the Anterior Interpositus Nucleus on the Kinematic and Dynamic Control of Multijoint Movement

2000 ◽  
Vol 84 (4) ◽  
pp. 1988-2000 ◽  
Author(s):  
Scott E. Cooper ◽  
John H. Martin ◽  
Claude Ghez
Keyword(s):  
Angular Displacement ◽  
Elbow Flexion ◽  
Elbow Flexor ◽  
Target Height ◽  
Flexor Muscle ◽  
Interpositus Nucleus ◽  
Interaction Torque ◽  
Muscle Torque ◽  
Phase Lead ◽  
Muscle Torques

We previously showed that inactivating the anterior interpositus nucleus in cats disrupts prehension; paw paths, normally straight and accurate, become curved, hypometric, and more variable. In the present study, we determined the joint kinematic and dynamic origins of this impairment. Animals were restrained in a hammock and trained to reach and grasp a cube of meat from a narrow food well at varied heights; movements were monitored using the MacReflex analysis system. The anterior interpositus nucleus was inactivated by microinjection of the GABA agonist muscimol (0.25–0.5 μg in 0.5 μL saline). For each joint, we computed the torque due to gravity, inertial resistance (termed self torque), interjoint interactions (termed interaction torque), and the combined effects of active muscle contraction and passive soft tissue stretch (termed generalized muscle torque). Inactivation produced significant reductions in the amplitude, velocity, and acceleration of elbow flexion. However, these movements continued to scale normally with target height. Shoulder extension was reduced by inactivation but wrist angular displacement and velocity were not. Inactivation also produced changes in the temporal coordination between elbow, shoulder, and wrist kinematics. Dynamic analysis showed that elbow flexion both before and during inactivation was produced by the combined action of muscle and interaction torque, but that the timing depended on muscle torque. Elbow interaction and muscle torques were scaled to target height both before and during inactivation. Inactivation produced significant reductions in elbow flexor interaction and muscle torques. The duration of elbow flexor muscle torque was prolonged to compensate for the reduction in flexor interaction torque. Shoulder extension was produced by extensor interaction and muscle torques both before and during inactivation. Inactivation produced a reduction in shoulder extension, primarily by reduced interaction torque, but without compensation. Wrist plantarflexion, which occurred during elbow flexion, was driven by plantarflexor interaction and gravitational torques both before and during inactivation. Muscle torque acted in the opposite direction with a phase lead to restrain the plantarflexor interaction torque. During inactivation, there was a reduction in plantarflexor interaction torque and a loss of the phase lead of the muscle torque. Our findings implicate the C1/C3 anterior interpositus zone of the cerebellum in the anticipatory control of intersegmental dynamics during reaching, which zone is required for coordinating the motions of the shoulder and wrist with those of the elbow. In contrast, this cerebellar zone does not play a role in scaling the movement to match a target.

1⁄4 Car Model for Suspension Trim Corrector Performances Evaluation

2016 ◽  
Vol 823 ◽  
pp. 205-210
Author(s):  
Adrian Ioan Niculescu
Keyword(s):  
Contact Force ◽  
Harmonic Functions ◽  
Degrees Of Freedom ◽  
The Body ◽  
Vertical Acceleration ◽  
Vertical Movements ◽  
The Road ◽  
Quarter Car Model ◽  
Car Model ◽  
Quarter Car

The paper presents a complex quarter car model obtained with ADAMS software, View module, useful in the first stage of suspension dimensioning and optimization.The model is equipped with compression and rebound stopper buffer and suspension trim corrector.The proposed quarter car model with two degrees of freedom (wheel and body) performs all these goals allowing changing:Geometrical elementsPosition of equilibrium, depending on vehicle load;Trim correction;Elastic and dissipative characteristics of the suspension and tire;Suspension stroke;Road profile, assessed either by simple or summation of harmonic functions or reproducing real roadsBuffers (for stroke limitation) position and characteristics;The models developed provide information on:Vertical stability assessed by vertical movements of the body and the longitudinal and transversal stability evaluated based on adherence characterized by wheel ground contact force and frequency of soil detachment wheel.Comfort assessed on the basis of body vertical acceleration and collision forces to the stroke ends.The body-road clearanceThe trim corrector efficiencyAll above performances evaluated function the road unevenness, acceleration, deceleration, turning regime.The damping characteristic is defined by damping forces at different speed for each strokes respectively one for rebound and other for compression.The contact force road-wheel is defined based tire rigidity law.The stopper buffer forces on rebound and compression are defined based each specific rigidity characteristics.The road excitation is realized with a function generator.The software allow the model evolution visualisation in real time, also generating the diagrams of displacements, forces, accelerations, speeds, for each elements or for relative evolution between diverse elements.The simulation was realized for unloaded and fully loaded car using a road generated by a sum of harmonic functions presented in equation (8).The excitation covers the specific frequencies area, being under the body frequencies up to the wheel proper frequencies.The realized ¼ car model, have reached the goal to evaluate the suspension trim correction advantages.The simulations confirm the trim corrector increases the suspension performances, thus for the analyzed case the trim corrector increase simultaneous:Body-ground clearance (evaluated by body higher increasing) between 18.5÷55.1 %Body stability (evaluated by maximal body displacement) between 9.8÷11.4 %Body comfort (evaluated by maximal body acceleration) between 3.4÷35.5 %Adherence (evaluated by maximal and RMS wheel-groundcontact force variation) between 7.0÷12.1 %Body and axles protection (evaluated by buffer strike force) between 10.8÷38.2 %

scholarly journals Ankle morphology amplifies calcaneus movement relative to triceps surae muscle shortening

2013 ◽  
Vol 115 (4) ◽  
pp. 468-473 ◽  
Author(s):  
R. Csapo ◽  
J. Hodgson ◽  
R. Kinugasa ◽  
V. R. Edgerton ◽  
S. Sinha
Keyword(s):  
Magnetic Resonance ◽  
Achilles Tendon ◽  
Ankle Joint ◽  
Sagittal Plane ◽  
Triceps Surae ◽  
Myotendinous Junction ◽  
Joint Movement ◽  
Center Of Rotation ◽  
Moment Arms ◽  
Plantarflexor Muscles

The present study investigated the mechanical role of the dorsoventral curvature of the Achilles tendon in the conversion of the shortening of the plantarflexor muscles into ankle joint rotation. Dynamic, sagittal-plane magnetic resonance spin-tagged images of the ankle joint were acquired in six healthy subjects during both passive and active plantarflexion movements driven by a magnetic resonance compatible servomotor-controlled foot-pedal device. Several points on these images were tracked to determine the 1) path and deformation of the Achilles tendon, 2) ankle's center of rotation, and 3) tendon moment arms. The degree of mechanical amplification of joint movement was calculated as the ratio of the displacements of the calcaneus and myotendinous junction. In plantarflexion, significant deflection of the Achilles tendon was evident in both the passive (165.7 ± 7.4°; 180° representing a straight tendon) and active trials (166.9 ± 8.8°). This bend in the dorsoventral direction acts to move the Achilles tendon closer to the ankle's center of rotation, resulting in an ∼5% reduction of moment arm length. Over the entire range of movement, the overall displacement of the calcaneus exceeded the displacement of the myotendinous junction by ∼37%, with the mechanical gains being smaller in dorsi- and larger in plantarflexed joint positions. This is the first study to assess noninvasively and in vivo using MRI the curvature of the Achilles tendon during both passive and active plantarflexion movements. The dorsoventral tendon curvature amplifies the shortening of the plantarflexor muscles, resulting in a greater displacement of the tendon's insertion into the calcaneus compared with its origin.

An Unlearned Principle for Controlling Natural Movements

1999 ◽  
Vol 82 (1) ◽  
pp. 255-259 ◽  
Author(s):  
Frank T.J.M. Zaal ◽  
Kristin Daigle ◽  
Gerald L. Gottlieb ◽  
Esther Thelen
Keyword(s):  
Degrees Of Freedom ◽  
Sagittal Plane ◽  
Arm Movement ◽  
First Year ◽  
Strong Constraint ◽  
A Value ◽  
Pointing Movements ◽  
Before And After ◽  
First Year Of Life ◽  
Coordination Patterns

Recently, Gottlieb and colleagues discovered a linear relation between elbow and shoulder dynamic torque in natural pointing movements in the sagittal plane. The present study investigates if the process of learning to reach involves discovering this linearity principle. We inspected torque data from four infants who were learning to reach and grab a toy in front of them. In a longitudinal study, we collected data both in the period before and after they performed their first successful reaches. Torque profiles at the shoulder and elbow were typically multipeaked and became more and more biphasic toward the end of the first year of life. Torques at the shoulder and elbow were correlated tightly for movements in the prereaching period as well as for reaches later in the year. Furthermore, slopes of a regression of shoulder dynamic torque on elbow dynamic torque were remarkably constant at a value ∼2.5–3.0. If linear synergy is used by the nervous system to reduce the controlled degrees of freedom, it will act as a strong constraint on the complex of possible coordination patterns for arm movement early in life. Natural reaching movements can capitalize on this constraint because it simplifies the process of learning to reach.

Coordinating movement at two joints: a principle of linear covariance

1996 ◽  
Vol 75 (4) ◽  
pp. 1760-1764 ◽  
Author(s):  
G. L. Gottlieb ◽  
Q. Song ◽  
D. A. Hong ◽  
G. L. Almeida ◽  
D. Corcos
Keyword(s):  
Degrees Of Freedom ◽  
Sagittal Plane ◽  
Linear Scaling ◽  
Joint Movement ◽  
Zero Crossings ◽  
Linear Dynamic ◽  
Important Principle ◽  
Linear Covariance ◽  
At Will ◽  
Scaling Rule

1. Six subjects performed fast, "single-joint" flexions at either the elbow or shoulder over three angular distances in a sagittal plane. Movement endpoints were located to require flexion of only a single, "focal" joint, without any external, mechanical constraint on the other, "nonfocal" joint. Three subjects performed another series of movements between two targets while moving along different paths and in which both joints were flexed. 2. We compared the torque patterns that were produced at the two joints. For single-joint movements, they were both biphasic pulses that accelerated and then decelerated the limb. 3. The torque at the nonfocal joint of a single joint movement was very close to linearly proportional to that at the focal joint throughout the movement. Elbow and shoulder torques differed by a linear scaling constant and went through extrema and zero crossings almost simultaneously. 4. In contrast, during movements in which subjects were explicitly instructed to use a hand path they would not naturally, use the linear interjoint torque scaling rule did not apply. This demonstrated that when we wish to move along a path between two targets that is not produced by linear torque covariation, we are able to modify that rule at will. 5. We speculate that linear, dynamic covariation of the torque patterns across two joints may be an important principle for reducing the number of degrees of freedom that the nervous system must independently control in performing unconstrained limb movements over naturally chosen paths.

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