The Mechanics of Perturbed Upper Limb Movement Control

2010 ◽  
Author(s):  
Kai Chen ◽  
Richard A. Foulds
Keyword(s):  
Upper Limb ◽  
Muscle Length ◽  
Movement Control ◽  
Elbow Flexion ◽  
Influential Factors ◽  
Least Square ◽  
Movement Trajectory ◽  
Time Duration ◽  
Inverse Dynamic ◽  
Control Signals

The dependence of muscle force on muscle length gives rise to a “spring - like” behavior which has been shown to play an important role during movement. This study extended this concept and incorporated the influential factors of the mechanical behavior of the neural, muscular and skeletal system on the control of elbow movement. A significant question in motor control is determining how information about movement is used to modify control signals to achieve desired performance. One theory proposed and supported by Feldman et. is the equilibrium point hypothesis (EPH). In it the central nervous system (CNS) reacts to movement as a shift of the limb’s equilibrium posture. The EPH drastically simplified the requisite computations for multi-joint movements and mechanical interactions with complex dynamic objects in the context. Because the neuromuscular system is spring-like, the instantaneous difference between the arm’s actual position and the equilibrium position specified by the neural activity can generate the requisite torques, avoiding the complex “inverse dynamic” of computing the torques at the joints. Moreover, this instantaneous difference serves as a potential source of movement control related to limb dynamics and associated movement-dependent torques when perturbations are added. In this paper, we have used an EPH model to examine changes to control signals for arm movements in the context of adding perturbations in format of forces or torques. The mechanical properties and reflex actions of muscles crossing the elbow joint were examined during a planned 1 radian voluntary elbow flexion movement. Brief unexpected torque/force pulses of identical magnitude and time duration (4.5 N flexion switching to 50 N extension within 120ms) were introduced at various points of a movement in randomly selected trials. Single perturbation was implemented in different trials during early, mid, stages of the movement by pre-programmed 6DOF robotic arm (MOOG FCS HapticMaster). Changes in movement trajectory induced by a torque/ force perturbation determined over the first 120 ms by a position prediction formulation, and then a modified and optimization K-B-I (stiffness-damping-inertia) model was fit to the responses for predicting both non-perturbed and perturbed movement of elbow. The stiffness and damping coefficients estimate during voluntary movements were compared to values recorded of different subjects during trials. A least square nonlinear optimization model was designed to help determine the optimized impedance a subject could generate, and the identified of adapted of K-B-I in perturbed upper limb movements confirmed our assumption.

Optimization of Stiffness and Damping in Modeling of Voluntary Elbow Flexions

2011 ◽  
Author(s):  
Kai Chen ◽  
Richard Foulds
Keyword(s):  
Arm Movement ◽  
Random Order ◽  
Influential Factors ◽  
Emg Activity ◽  
Control Parameters ◽  
Skeletal System ◽  
Time Duration ◽  
Control Signals ◽  
Stiffness And Damping ◽  
Virtual Trajectory

A subsequent study of obstructed voluntary arm movement extended the relative damping concept, and incorporated the influential factors of the mechanical behavior of the neural, muscular and skeletal system in the control and coordination of arm posture and movement. A significant problem of the study is how this information should be used to modify control signals to achieve desired performance. This study used an Equilibrium Point Hypothesis (EPH) model to examine changes of controlling signals for arm movements in the context of adding perturbation/load in the form of forces/torques. The mechanical properties and reflex actions of muscles of the elbow joint were examined. Brief unexpected torque/force pulses of identical magnitude and time duration were introduced at different stages of the movement in a random order by a pre-programmed 3 degree of freedom (DOF) robotic arm (MOOG FCS HapticMaster). Key to this research is the optimization of B and K for each subject based on their HM only experimental data. The results shown in each of sections confirm that those parameters. Along with an EMG determined VT can be used successfully to model the perturbed trials. The results also show that the subjects may maintain the same control parameters (virtual trajectory, stiffness and damping) regardless of added perturbations that cause substantial changes in EMG activity and kinematics.

Sensitivity Analysis of Dynamics System in the Upper Limb Movement Control

2012 ◽  
Author(s):  
Kai Chen ◽  
Richard A. Foulds
Keyword(s):  
Sensitivity Analysis ◽  
Upper Limb ◽  
Impedance Control ◽  
Muscle Length ◽  
Movement Control ◽  
Arm Movement ◽  
Human Movement ◽  
Limb Movement ◽  
Feedback Information ◽  
Analysis Of Dynamics

The dependence of muscle force on muscle length gives rise to a “spring–like” behavior which has been shown to play an important role during human movement. Neville Hogan (Hogan, 1985) proposed a mathematical model in terms of impedance control of arm movement. Discussing this work, Dr. Hogan admits that it can not effectively model all aspects of the performance of the system. He said “Controlling the complete dynamic behavior of the limb may be beyond the capacity of the central nervous system. If the disturbance is sufficiently abrupt, then, because of the inevitable transmission delays, continuous intervention based on neural feedback information will not be a feasible method of modulating these quantities.”. However, the model proposed in this study, accomplished most the work which Hogan believed was not feasible. In order to validate the result of proposed model, this study perform sensitivity analysis between the results produced by the dynamics system and the results measured, the comparison showed the difference between these two results were less than 10%, which strongly support the idea that proposed dynamic model can accurately reflect dynamics system in the upper limb movement control.

scholarly journals Determination of emergency roads to emergency accommodation using loss analysis results

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Sajad Ganjehi ◽  
Khadijeh Norouzi Khatiri
Keyword(s):  
Estimation Method ◽  
Emergency Evacuation ◽  
Influential Factors ◽  
Urban Crisis ◽  
Time Duration ◽  
Loss Analysis ◽  
Expert Choice ◽  
Data Layers ◽  
Temporary Accommodation

AbstractTeh present study aims to identify proper places to build temporary accommodation for people and accessible roads using damage analysis results during a probable earthquake. Teh HAZUS damage estimation method, which is one of teh most common ones currently used in teh world, was used in dis study. Teh influential factors in locating teh temporary accommodation in Shiraz were studied by using damage results, AHP model, and Expert Choice software. Then, map for temporary accommodation was prepared. By integrating layers, teh ultimate map of optimal locating for temporary accommodation was presented. Subsequently, all teh parameters influencing teh safety of emergency evacuation and relief network were identified and teh impact rate of each one was determined based on experts’ opinions through AHP. Based on teh importance of each index, roads were weighed and coded. Then, teh optimal safe road for relief and emergency evacuation was proposed. Teh results suggested dat relief roads are different based on different indices and teh optimal road was obtained through overlapping teh data layers according to teh importance of each parameter. dis optimal road could provide maximum services in teh minimum time duration and subsequently create capacity building in urban crisis management.

scholarly journals Muscle length and joint angle influence spinal but not corticospinal excitability to the biceps brachii across forearm postures

2019 ◽  
Vol 122 (1) ◽  
pp. 413-423 ◽  
Author(s):  
Davis A. Forman ◽  
Daniel Abdel-Malek ◽  
Christopher M. F. Bunce ◽  
Michael W. R. Holmes
Keyword(s):  
Isometric Contraction ◽  
Elbow Joint ◽  
Joint Angle ◽  
Biceps Brachii ◽  
Motor Evoked Potentials ◽  
Muscle Length ◽  
Elbow Flexion ◽  
Corticospinal Excitability ◽  
Biceps Brachii Muscle ◽  
Spinal Excitability

Forearm rotation (supination/pronation) alters corticospinal excitability to the biceps brachii, but it is unclear whether corticospinal excitability is influenced by joint angle, muscle length, or both. Thus the purpose of this study was to separately examine elbow joint angle and muscle length on corticospinal excitability. Corticospinal excitability to the biceps and triceps brachii was measured using motor evoked potentials (MEPs) elicited via transcranial magnetic stimulation. Spinal excitability was measured using cervicomedullary motor evoked potentials (CMEPs) elicited via transmastoid electrical stimulation. Elbow angles were manipulated with a fixed biceps brachii muscle length (and vice versa) across five unique postures: 1) forearm neutral, elbow flexion 90°; 2) forearm supinated, elbow flexion 90°; 3) forearm pronated, elbow flexion 90°; 4) forearm supinated, elbow flexion 78°; and 5) forearm pronated, elbow flexion 113°. A musculoskeletal model determined biceps brachii muscle length for postures 1–3, and elbow joint angles ( postures 4–5) were selected to maintain biceps length across forearm orientations. MEPs and CMEPs were elicited at rest and during an isometric contraction of 10% of maximal biceps muscle activity. At rest, MEP amplitudes to the biceps were largest during supination, which was independent of elbow joint angle. CMEP amplitudes were not different when the elbow was fixed at 90° but were largest in pronation when muscle length was controlled. During an isometric contraction, there were no significant differences across forearm postures for either MEP or CMEP amplitudes. These results highlight that elbow joint angle and biceps brachii muscle length can each independently influence spinal excitability. NEW & NOTEWORTHY Changes in upper limb posture can influence the responsiveness of the central nervous system to artificial stimulations. We established a novel approach integrating neurophysiology techniques with biomechanical modeling. Through this approach, the effects of elbow joint angle and biceps brachii muscle length on corticospinal and spinal excitability were assessed. We demonstrate that spinal excitability is uniquely influenced by joint angle and muscle length, and this highlights the importance of accounting for muscle length in neurophysiological studies.

Mechanical Evaluation of the Pronator Teres Rerouting Tendon Transfer

2004 ◽  
Vol 29 (3) ◽  
pp. 257-262 ◽  
Author(s):  
H. E. J. VEEGER ◽  
M. KREULEN ◽  
M. J. C. SMEULDERS
Keyword(s):  
Biceps Brachii ◽  
External Rotation ◽  
Three Dimensional ◽  
Muscle Length ◽  
Biomechanical Model ◽  
Elbow Flexion ◽  
Axial Rotation ◽  
Original Position ◽  
Pronator Quadratus ◽  
Pronator Teres

We simulated pronator teres rerouting using a three-dimensional biomechanical model of the arm. Simulations comprised the evaluation of changes in muscle length and the moment arm of pronator teres with changes in forearm axial rotation and elbow flexion. The rerouting of Pronator Teres was simulated by defining a path for it through the interosseous membrane with re-attachment to its original insertion. However the effect of moving the insertion to new positions, 2 cm below and above, the original position was also assessed. The effect on total internal rotation and external rotation capacity was determined by calculating the potential moments for pronator teres, supinator, pronator quadratus, biceps brachii and brachioradialis. Pronator teres was found to be a weak internal rotator in extreme pronation, but a strong internal rotator in neutral rotation and in supination. After rerouting pronator teres was only a strong external rotator in full pronation and not at other forearm positions, where the effect of rerouting was comparable to a release procedure.

scholarly journals Distinction of Students and Expert Therapists Based on Therapeutic Motions on a Robotic Device Using Support Vector Machine

2020 ◽  
Vol 40 (6) ◽  
pp. 790-797
Author(s):  
Koike Yuji ◽  
Suzuki Makoto ◽  
Okino Akihisa ◽  
Takeda Kazuhisa ◽  
Takanami Yasuhiro ◽  
...  
Keyword(s):  
Support Vector Machine ◽  
Exercise Therapy ◽  
Upper Limb ◽  
Peak Velocity ◽  
Movement Time ◽  
Elbow Flexion ◽  
Flexion Angle ◽  
Support Vector ◽  
Robot Arm ◽  
Clinical Practices

Abstract Purpose To clarify the feature values of exercise therapy that can differentiate students and expert therapists and use this information as a reference for exercise therapy education. Methods The participants were therapists with 5 or more years of clinical experience and 4th year students at occupational therapist training schools who had completed their clinical practices. The exercise therapy task included Samothrace (code name, SAMO) exercises implemented on the elbow joint based on the elbow flexion angle, angular velocity, and exercise interval recordings. For analyses and student/therapist comparisons, the peak flexion angle, peak velocity, and movement time were calculated using data on elbow angle changes acquired via SAMO. Subsequently, bootstrap data were generated to differentiate between the exercise therapy techniques adopted by therapists and students, and a support vector machine was used to generate four types of data combinations with the peak flexion angle, peak velocity, and movement time values. These data were used to estimate and compare the respective accuracies with the Friedman test. Results The peak flexion angles were significantly smaller in the case of students. Furthermore, the peak velocities were larger, the peak flexion angles were smaller, and the movement times were shorter compared with those of therapists. The combination of peak velocity and peak flexion angle yielded the highest diagnostic accuracies. Conclusion When students and therapists performed upper limb exercise therapy techniques based on the kinematics movement of a robot arm, the movement speeds and joint angles differed. The combination of peak velocity and peak flexion angle was the most effective classifier used for the differentiation of the abilities of students and therapists. The peak velocity and peak flexion angle of the therapist group can be used as a reference for students when they learn upper limb therapeutic exercise techniques.

Human upper-limb force capacities evaluation with robotic models for ergonomic applications: effect of elbow flexion

2015 ◽  
Vol 19 (4) ◽  
pp. 440-449 ◽  
Author(s):  
Vincent Hernandez ◽  
Nasser Rezzoug ◽  
Julien Jacquier-Bret ◽  
Philippe Gorce
Keyword(s):  
Upper Limb ◽  
Elbow Flexion ◽  
Human Upper Limb

The reproducibility and responsiveness of subjective assessment of upper limb associated reactions in people with acquired brain injury during walking

2019 ◽  
Vol 34 (2) ◽  
pp. 252-262 ◽  
Author(s):  
Michelle B Kahn ◽  
Ross A Clark ◽  
Kelly J Bower ◽  
Benjamin F Mentiplay ◽  
Pua Yong Hao ◽  
...  
Keyword(s):  
Brain Injury ◽  
Upper Limb ◽  
Acquired Brain Injury ◽  
Elbow Flexion ◽  
Subjective Assessment ◽  
Flexion Angle ◽  
International Classification Of Functioning ◽  
Post Injury ◽  
Rehabilitation Centre ◽  
Injury Rehabilitation

Objective: The aim of this study is to determine inter-rater, test–retest and intra-rater reproducibility and responsiveness of subjective assessment of upper limb associated reactions in people with acquired brain injury using (1) the ‘Qualifiers Scale’ of the International Classification of Functioning, Disability and Health Framework, and (2) visually estimated elbow flexion angle during walking. Design: Observational study. Setting: A brain injury rehabilitation centre, Melbourne, Australia. Subjects: People with acquired brain injury and upper limb associated reactions and experienced neurological physiotherapists. Main measures: The Qualifiers Scale applied to individual upper limb joints and global associated reaction on a 5-point scale (0–4), a summed upper limb severity score and visually estimated elbow flexion angle. Results: A total of 42 people with acquired brain injury (mean age: 48.4 ± 16.5 years) were videoed walking at self-selected and fast speeds. A subset of 30 chronic brain injury participants (mean time post injury: 8.2 ± 9.3 years) were reassessed one week later for retest reproducibility. Three experienced neurological physiotherapists (mean experience: 22.7 ± 9.1 years) viewed these videos and subjectively rated the upper limb associated reactions. Strong-to-very strong test–retest, intra- and inter-rater reproducibility was found for elbow flexion angle (ICC > 0.86) and the Qualifiers Scale applied to global and individual upper limb joints (ICC > 0.60). Responsiveness of change from self-selected to fast walking speed (mean increase 0.46 m/s) was highest for elbow flexion angle (effect size = 0.83) and low-to-moderate for the Qualifiers Scale. Conclusion: Subjectively rated associated reactions during walking demonstrated strong reproducibility and moderate responsiveness to speed change. The Qualifiers Scale and elbow flexion angle can both subjectively quantify associated reactions during walking in a clinical setting.

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