scholarly journals Evaluation of force feedback in walking using joint torques as 'naturalistic' stimuli

2021 ◽  
Author(s):  
Sasha N. Zill ◽  
Chris J Dallmann ◽  
Nicholas Szczecinski ◽  
Ansgar Büschges ◽  
Josef Schmitz
Keyword(s):  
Force Feedback ◽  
Firing Frequency ◽  
Joint Torques ◽  
Stick Insects ◽  
Motor Activities ◽  
Reaction Forces ◽  
Body Load ◽  
Vertical Ground ◽  
Horizontal Substrate ◽  
Vertical Ground Reaction Forces

Control of adaptive walking requires the integration of sensory signals of muscle force and load. We have studied how mechanoreceptors (tibial campaniform sensilla) encode 'naturalistic' stimuli derived from joint torques of stick insects walking on a horizontal substrate. Previous studies showed that forces applied to the legs using the mean torque profiles of a proximal joint were highly effective in eliciting motor activities. However, substantial variations in torque direction and magnitude occurred at the more distal femoro-tibial joint, which can generate braking or propulsive forces and provide lateral stability. To determine how these forces are encoded, we utilized torque waveforms of individual steps that had maximum values in stance in the directions of flexion or extension. Analysis of kinematic data showed that the torques in different directions tended to occur in different ranges of joint angles. Variations within stance were not accompanied by comparable changes in joint angle but often reflected vertical ground reaction forces and leg support of body load. Application of torque waveforms elicited sensory discharges with variations in firing frequency similar to those seen in freely walking insects. All sensilla directionally encoded the dynamics of force increases and showed hysteresis to transient force decreases. Smaller receptors exhibited more tonic firing. Our findings suggest that dynamic sensitivity in force feedback can modulate ongoing muscle activities to stabilize distal joints when large forces are generated at proximal joints. Further, use of 'naturalistic' stimuli can reproduce characteristics seen in freely moving animals that are absent in conventional restrained preparations.

scholarly journals Joint angle estimation with wavelet neural networks

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Saaveethya Sivakumar ◽  
Alpha Agape Gopalai ◽  
King Hann Lim ◽  
Darwin Gouwanda ◽  
Sunita Chauhan
Keyword(s):  
Gait Analysis ◽  
Real Time ◽  
Monitoring Applications ◽  
Reaction Forces ◽  
Multiple Sensor ◽  
Vertical Ground ◽  
Overall Performance ◽  
Gait Monitoring ◽  
Vertical Ground Reaction Forces ◽  
And Control

AbstractThis paper presents a wavelet neural network (WNN) based method to reduce reliance on wearable kinematic sensors in gait analysis. Wearable kinematic sensors hinder real-time outdoor gait monitoring applications due to drawbacks caused by multiple sensor placements and sensor offset errors. The proposed WNN method uses vertical Ground Reaction Forces (vGRFs) measured from foot kinetic sensors as inputs to estimate ankle, knee, and hip joint angles. Salient vGRF inputs are extracted from primary gait event intervals. These selected gait inputs facilitate future integration with smart insoles for real-time outdoor gait studies. The proposed concept potentially reduces the number of body-mounted kinematics sensors used in gait analysis applications, hence leading to a simplified sensor placement and control circuitry without deteriorating the overall performance.

scholarly journals Hindlimb muscular activity, kinetics and kinematics of cats jumping to their maximum achievable heights

1981 ◽  
Vol 91 (1) ◽  
pp. 73-86 ◽  
Author(s):  
F. E. Zajac ◽  
M. R. Zomlefer ◽  
W. S. Levine
Keyword(s):  
Vertical Jump ◽  
Muscular Activity ◽  
Dynamic State ◽  
Extensor Muscles ◽  
Ankle Joints ◽  
Flexor Muscles ◽  
Reaction Forces ◽  
Vertical Ground ◽  
Vertical Ground Reaction Forces ◽  
Propulsion Phase

Cats were trained to jump from a force platform to their maximum achievable heights. Vertical ground reaction forces developed by individual hindlimbs showed that the propulsion phase consists of two epochs. During the initial “preparatory phase' the cat can traverse many different paths. Irrespective of the path traversed, however, the cat always attains the same position, velocity and momentum at the end of this phase. Starting from this dynamic state the cat during the subsequent “launching phase' (about 150 ms long) generates significant propulsion as its hindlimbs develop force with identical, stereotypic profiles. Cinematographic data, electromyographic data, and computed torques about the hip, knee and ankle joints indicate that during the jump proximal extensor musculature is activated before distal musculature. During terminal experiments when the hindlimb was set at positions corresponding to those in the jump, isometric torques produced by tetanic stimulation of groups of extensor and flexor muscles were compared with computed torques developed by the same cat during previous jumps. These comparisons suggest that extensor muscles of the hindlimb are fully activated during the maximal vertical jump.

scholarly journals Hip and Knee Kinematics and Kinetics During Landing Tasks After Anterior Cruciate Ligament Reconstruction: A Systematic Review and Meta-Analysis

2018 ◽  
Vol 53 (2) ◽  
pp. 144-159 ◽  
Author(s):  
Adam S. Lepley ◽  
Christopher M. Kuenze
Keyword(s):  
Ligament Reconstruction ◽  
Cruciate Ligament ◽  
Meta Analysis ◽  
Knee Extension ◽  
Injured Limb ◽  
Reaction Forces ◽  
Vertical Ground ◽  
Anterior Cruciate ◽  
Vertical Ground Reaction Forces ◽  
Kinematics And Kinetics

Objective:  To evaluate the current evidence concerning kinematic and kinetic strategies adopted during dynamic landing tasks by patients with anterior cruciate ligament reconstruction (ACLR). Data Sources:  PubMed, Web of Science. Study Selection:  Original research articles that evaluated kinematics or kinetics (or both) during a landing task in those with a history of ACLR were included. Data Extraction:  Methodologic quality was assessed using the modified Downs and Black checklist. Means and standard deviations for knee or hip (or both) kinematics and kinetics were used to calculate Cohen d effect sizes and corresponding 95% confidence intervals between the injured limb of ACLR participants and contralateral or healthy matched limbs. Data were further stratified by landing tasks, either double- or single-limb landing. A random-effects–model meta-analysis was used to calculate pooled effect sizes and 95% confidence intervals. Data Synthesis:  The involved limbs of ACLR patients demonstrated clinically and significantly lower knee-extension moments during double-legged landing compared with healthy contralateral limbs and healthy control limbs (Cohen d range = −0.81 to −1.23) and decreased vertical ground reaction forces when compared with healthy controls, regardless of task (Cohen d range = −0.39 to −1.75). Conclusions:  During single- and double-legged landing tasks, individuals with ACLR demonstrated meaningful reductions in injured-limb knee-extension moments and vertical ground reaction forces. These findings indicate potential unloading of the injured limb after ACLR, which may have significant implications for secondary ACL injury and long-term joint health.

Comparison of overground and treadmill vertical ground reaction forces

1995 ◽  
Vol 3 (2) ◽  
pp. 86
Author(s):  
H.John Yack ◽  
Carole Tucker ◽  
Scott C White Heather Collins
Keyword(s):  
Ground Reaction Forces ◽  
Reaction Forces ◽  
Vertical Ground ◽  
Vertical Ground Reaction Forces

Effects of partial immersion in water on vertical ground reaction forces and weight distribution in dogs

2010 ◽  
Vol 71 (12) ◽  
pp. 1413-1416 ◽  
Author(s):  
David Levine ◽  
Denis J. Marcellin-Little ◽  
Darryl L. Millis ◽  
Verena Tragauer ◽  
Jason A. Osborne
Keyword(s):  
Weight Distribution ◽  
Ground Reaction Forces ◽  
Partial Immersion ◽  
Reaction Forces ◽  
Vertical Ground ◽  
Vertical Ground Reaction Forces
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