Optimal Combination of Minimum Degrees of Freedom to be Actuated in the Lower Limbs to Facilitate Arm-Free Paraplegic Standing

2007 ◽  
Vol 129 (6) ◽  
pp. 838-847 ◽  
Author(s):  
Joon-young Kim ◽  
James K. Mills ◽  
Albert H. Vette ◽  
Milos R. Popovic
Keyword(s):  
Lower Limb ◽  
Degrees Of Freedom ◽  
Three Dimensional ◽  
Optimal Combination ◽  
Lower Limbs ◽  
Free Standing ◽  
Joint Torques ◽  
Flexion Extension ◽  
Hip Abduction ◽  
The Individual

Arm-free paraplegic standing via functional electrical stimulation (FES) has drawn much attention in the biomechanical field as it might allow a paraplegic to stand and simultaneously use both arms to perform daily activities. However, current FES systems for standing require that the individual actively regulates balance using one or both arms, thus limiting the practical use of these systems. The purpose of the present study was to show that actuating only six out of 12 degrees of freedom (12-DOFs) in the lower limbs to allow paraplegics to stand freely is theoretically feasible with respect to multibody stability and physiological torque limitations of the lower limb DOF. Specifically, the goal was to determine the optimal combination of the minimum DOF that can be realistically actuated using FES while ensuring stability and able-bodied kinematics during perturbed arm-free standing. The human body was represented by a three-dimensional dynamics model with 12-DOFs in the lower limbs. Nakamura’s method (Nakamura, Y., and Ghodoussi, U., 1989, “Dynamics Computation of Closed-Link Robot Mechanisms With Nonredundant and Redundant Actuators,” IEEE Trans. Rob. Autom., 5(3), pp. 294–302) was applied to estimate the joint torques of the system using experimental motion data from four healthy subjects. The torques were estimated by applying our previous finding that only 6 (6-DOFs) out of 12-DOFs in the lower limbs need to be actuated to facilitate stable standing. Furthermore, it was shown that six cases of 6-DOFs exist, which facilitate stable standing. In order to characterize each of these cases in terms of the torque generation patterns and to identify a potential optimal 6-DOF combination, the joint torques during perturbations in eight different directions were estimated for all six cases of 6-DOFs. The results suggest that the actuation of both ankle flexion∕extension, both knee flexion∕extension, one hip flexion∕extension, and one hip abduction∕adduction DOF will result in the minimum torque requirements to regulate balance during perturbed standing. To facilitate unsupported FES-assisted standing, it is sufficient to actuate only 6-DOFs. An optimal combination of 6-DOFs exists, for which this system can generate able-bodied kinematics while requiring lower limb joint torques that are producible using contemporary FES technology. These findings suggest that FES-assisted arm-free standing of paraplegics is theoretically feasible, even when limited by the fact that muscles actuating specific DOFs are often denervated or difficult to access.

scholarly journals Reliability of a New Portable Dynamometer for Assessing Hip and Lower Limb Strength

2021 ◽  
Vol 11 (8) ◽  
pp. 3391
Author(s):  
Jan Marušič ◽  
Goran Marković ◽  
Nejc Šarabon
Keyword(s):  
Lower Limb ◽  
External Rotation ◽  
Peak Torque ◽  
Knee Extension ◽  
Lower Limb Muscles ◽  
Lower Limb Strength ◽  
Flexion Extension ◽  
Strength Tests ◽  
Hip Abduction ◽  
Maximal Peak

The purpose of this study was to evaluate intra- and inter-session reliability of the new, portable, and externally fixated dynamometer called MuscleBoard® for assessing the strength of hip and lower limb muscles. Hip abduction, adduction, flexion, extension, internal and external rotation, knee extension, ankle plantarflexion, and Nordic hamstring exercise strength were measured in three sessions (three sets of three repetitions for each test) on 24 healthy and recreationally active participants. Average and maximal value of normalized peak torque (Nm/kg) from three repetitions in each set and agonist:antagonist ratios (%) were statistically analyzed; the coefficient of variation and intra-class correlation coefficient (ICC2,k) were calculated to assess absolute and relative reliability, respectively. Overall, the results display high to excellent intra- and inter-session reliability with low to acceptable within-individual variation for average and maximal peak torques in all bilateral strength tests, while the reliability of unilateral strength tests was moderate to good. Our findings indicate that using the MuscleBoard® dynamometer can be a reliable device for assessing and monitoring bilateral and certain unilateral hip and lower limb muscle strength, while some unilateral strength tests require some refinement and more extensive familiarization.

Do Arm Postures Vary With the Speed of Reaching?

1999 ◽  
Vol 81 (5) ◽  
pp. 2582-2586 ◽  
Author(s):  
Kiisa C. Nishikawa ◽  
Sara T. Murray ◽  
Martha Flanders
Keyword(s):  
Degrees Of Freedom ◽  
Three Dimensional ◽  
Optimal Solution ◽  
Reaching Movements ◽  
Total Force ◽  
Joint Torques ◽  
Dynamic Factors ◽  
Human Arm ◽  
Wide Range ◽  
Dynamic Forces

Do arm postures vary with the speed of reaching? For reaching movements in one plane, the hand has been observed to follow a similar path regardless of speed. Recent work on the control of more complex reaching movements raises the question of whether a similar “speed invariance” also holds for the additional degrees of freedom. Therefore we examined human arm movements involving initial and final hand locations distributed throughout the three-dimensional (3D) workspace of the arm. Despite this added complexity, arm kinematics (summarized by the spatial orientation of the “plane of the arm” and the 3D curvature of the hand path) changed very little for movements performed over a wide range of speeds. If the total force (dynamic + quasistatic) had been optimized by the control system (e.g., as in a minimization of the change in joint torques or the change in muscular forces), the optimal solution would change with speed; slow movements would reflect the minimal antigravity torques, whereas fast movements would be more strongly influenced by dynamic factors. The speed-invariant postures observed in this study are instead consistent with a hypothesized optimization of only the dynamic forces.

The Synergistic Organization of Muscle Recruitment Constrains Visuomotor Adaptation

2009 ◽  
Vol 101 (5) ◽  
pp. 2263-2269 ◽  
Author(s):  
Aymar de Rugy ◽  
Mark R. Hinder ◽  
Daniel G. Woolley ◽  
Richard G. Carson
Keyword(s):  
Time Course ◽  
Neural Circuits ◽  
Visual Target ◽  
Sensory Information ◽  
Visuomotor Adaptation ◽  
Visuomotor Rotation ◽  
Joint Torques ◽  
Flexion Extension ◽  
Isometric Torque ◽  
The Individual

Reaching to visual targets engages the nervous system in a series of transformations between sensory information and motor commands. That which remains to be determined is the extent to which the processes that mediate sensorimotor adaptation to novel environments engage neural circuits that represent the required movement in joint-based or muscle-based coordinate systems. We sought to establish the contribution of these alternative representations to the process of visuomotor adaptation. To do so we applied a visuomotor rotation during a center-out isometric torque production task that involved flexion/extension and supination/pronation at the elbow-joint complex. In separate sessions, distinct half-quadrant rotations (i.e., 45°) were applied such that adaptation could be achieved either by only rescaling the individual joint torques (i.e., the visual target and torque target remained in the same quadrant) or by additionally requiring torque reversal at a contributing joint (i.e., the visual target and torque target were in different quadrants). Analysis of the time course of directional errors revealed that the degree of adaptation was lower (by ∼20%) when reversals in the direction of joint torques were required. It has been established previously that in this task space, a transition between supination and pronation requires the engagement of a different set of muscle synergists, whereas in a transition between flexion and extension no such change is required. The additional observation that the initial level of adaptation was lower and the subsequent aftereffects were smaller, for trials that involved a pronation–supination transition than for those that involved a flexion–extension transition, supports the conclusion that the process of adaptation engaged, at least in part, neural circuits that represent the required motor output in a muscle-based coordinate system.

Multibody Analysis and Control of a Full-Wrist Exoskeleton for Tremor Alleviation

2020 ◽  
Vol 142 (12) ◽  
Author(s):  
Jiamin Wang ◽  
Oumar R. Barry
Keyword(s):  
Degrees Of Freedom ◽  
Controller Design ◽  
Wrist Joint ◽  
Three Dimensional ◽  
Design Parameters ◽  
Light Power ◽  
Multibody Modeling ◽  
Flexion Extension ◽  
Reliable Performance ◽  
Rotational Joint

Abstract Uncontrollable shaking in the human wrist, caused by pathological tremor, can significantly undermine the power and accuracy in object manipulation. In this paper, the design of a tremor alleviating wrist exoskeleton (TAWE) is introduced. Unlike the works in the literature that only consider the flexion/extension (FE) motion, in this paper, we model the wrist joint as a constrained three-dimensional (3D) rotational joint accounting for the coupled FE and radial/ulnar deviation (RUD) motions. Hence TAWE, which features a six degrees-of-freedom (DOF) rigid linkage structure, aims to accurately monitor, suppress tremors, and provide light-power augmentation in both FE and RUD wrist motions. The presented study focuses on providing a fundamental understanding of the feasibility of TAWE through theoretical analyses. The analytical multibody modeling of the forearm–TAWE assembly provides insight into the necessary conditions for control, which indicates that reliable control conditions in the desired workspace can be acquired by tuning the design parameters. Nonlinear regressions are then implemented to identify the information that is crucial to the controller design from the unknown wrist kinematics. The proposed analytical model is validated numerically with V-REP and the result shows good agreement. Simulations also demonstrate the reliable performance of TAWE under controllers designed for tremor suppression and movement assistance.

Helical Axis Data Visualization and Analysis of the Knee Joint Articulation

2016 ◽  
Vol 138 (9) ◽  
Author(s):  
Ricardo Manuel Millán Vaquero ◽  
Alexander Vais ◽  
Sean Dean Lynch ◽  
Jan Rzepecki ◽  
Karl-Ingo Friese ◽  
...  
Keyword(s):  
Knee Joint ◽  
Lie Algebra ◽  
Degrees Of Freedom ◽  
Spatial Scales ◽  
Three Dimensional ◽  
Patient Specific ◽  
Helical Axis ◽  
Accurate Analysis ◽  
Related Data ◽  
Flexion Extension

We present processing methods and visualization techniques for accurately characterizing and interpreting kinematical data of flexion–extension motion of the knee joint based on helical axes. We make use of the Lie group of rigid body motions and particularly its Lie algebra for a natural representation of motion sequences. This allows to analyze and compute the finite helical axis (FHA) and instantaneous helical axis (IHA) in a unified way without redundant degrees of freedom or singularities. A polynomial fitting based on Legendre polynomials within the Lie algebra is applied to provide a smooth description of a given discrete knee motion sequence which is essential for obtaining stable instantaneous helical axes for further analysis. Moreover, this allows for an efficient overall similarity comparison across several motion sequences in order to differentiate among several cases. Our approach combines a specifically designed patient-specific three-dimensional visualization basing on the processed helical axes information and incorporating computed tomography (CT) scans for an intuitive interpretation of the axes and their geometrical relation with respect to the knee joint anatomy. In addition, in the context of the study of diseases affecting the musculoskeletal articulation, we propose to integrate the above tools into a multiscale framework for exploring related data sets distributed across multiple spatial scales. We demonstrate the utility of our methods, exemplarily processing a collection of motion sequences acquired from experimental data involving several surgery techniques. Our approach enables an accurate analysis, visualization and comparison of knee joint articulation, contributing to the evaluation and diagnosis in medical applications.

A Three-Dimensional Biomechanical Analysis of the Cat Ankle Joint Complex: I. Active and Passive Postural Mechanics

1999 ◽  
Vol 15 (2) ◽  
pp. 95-105 ◽  
Author(s):  
John H. Lawrence ◽  
T. Richard Nichols
Keyword(s):  
Ankle Joint ◽  
Three Dimensional ◽  
Joint Stiffness ◽  
Biomechanical Analysis ◽  
Reference Plane ◽  
Joint Orientation ◽  
Orthogonal Axis ◽  
Joint Torques ◽  
Flexion Extension ◽  
Force Moment

Muscle actions are often defined with respect to a single anatomical reference plane based on a “predominant” functional activity. Yet animals must control posture and movement within a three-dimensional (3-D) environment, exerting control over more than one reference plane when responding to a 3-D array of perturbing forces. Consequently, enhanced knowledge concerning the 3-D torque capabilities of certain appendicular muscles might provide for greater understanding of the biomechanical basis for motor control. We propose that the cat postural control mechanism utilizes the inherent 3-D mechanical actions of ankle flexors and extensors to maintain extra-saggital joint stiffness. We used a 6 degree-of-freedom force-moment sensor to assess the effect of ankle joint orientation on the 3-D nature of isometric joint torques evoked by electrical stimulation of muscles crossing the AJC in the deeply anesthetized cat. An orthogonal axis system was established at the designated ankle rotation center, such that pitch (defining flexion-extension), yaw (abduction-adduction), and roll (inversion-eversion) axis torques were calculated. Experimental results show that the classical cat ankle flexor and extensors evoke large extra-sagittal torques as well. Also, the hind limb levering system stabilizes the AJC against large yaw and roll rotations away from the control position.

scholarly journals Relationships between Hip Flexibility and Pitching Biomechanics in Adolescent Baseball Pitchers

2021 ◽  
Author(s):  
Maxwell L. Albiero ◽  
Wesley Kokott ◽  
Cody Dziuk ◽  
Janelle A. Cross
Keyword(s):  
External Rotation ◽  
Pearson Correlation ◽  
Three Dimensional ◽  
Correlation Coefficients ◽  
Kinematic Chain ◽  
Abduction Angle ◽  
Cross Sectional ◽  
Flexion Extension ◽  
Hip Abduction ◽  
Baseball Pitchers

Abstract Context: Inadequate hip active range of motion (AROM) may stifle the energy flow through the kinematic chain and decrease pitching performance while increasing the risk for pitcher injury. Objective: To examine the relationship of hip AROM and pitching biomechanics during a fastball pitch in adolescent baseball pitchers. Design: Cross-Sectional study. Setting: Biomechanics laboratory. Participants: A voluntary sample of 21 adolescent baseball pitchers (16.1 ± 0.8 yrs.; 183.9 ± 5.2 cm; 77.9 ± 8.3 kg). Main Outcome Measure (s): Bilateral hip internal rotation (IR), external rotation (ER), flexion, extension, and abduction AROM were measured. Three-dimensional biomechanics were assessed as participants threw from an indoor pitching mound to a strike zone net at regulation distance. Pearson correlation coefficients were used to determine correlations between hip AROM and biomechanical metrics. Results: Statistically significant negative correlations were found at foot contact between back hip ER AROM and back hip abduction angle (p=0.030, r=−0.474), back hip ER AROM and torso rotation angle (p=0.032, r=−0.468),and back hip abduction AROM and lead hip abduction angle (p=0.037, r=−0.458). Back hip extension AROM was positively correlated with increased stride length (p=0.043, r=0.446). Lead hip abduction AROM was also positively correlated with normalized elbow varus torque (p=0.034, r=0.464). Conclusions: There were several relationships between hip AROM and biomechanical variables during the pitching motion. The findings support the influence hip AROM can have on pitching biomechanics. Overall, greater movement at the hips allows for the kinematic chain to work at its maximal efficiency, increasing pitch velocity potential.

scholarly journals Design and Simulation Analysis of a Robot-Assisted Gait Trainer with the PBWS System

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Jiancheng (Charles) Ji ◽  
Yufeng Wang ◽  
Guoqing Zhang ◽  
Yuanyuan Lin ◽  
Guoxiang Wang
Keyword(s):  
Lower Limb ◽  
Degrees Of Freedom ◽  
Gait Cycle ◽  
Simulation Analysis ◽  
The Elderly ◽  
Lower Limbs ◽  
Robot Assisted ◽  
Limb Rehabilitation ◽  
Gait Trainer ◽  
Lower Limb Rehabilitation

In response to the ever-increasing demand of lower limb rehabilitation, this paper presents a novel robot-assisted gait trainer (RGT) to assist the elderly and the pediatric patients with neurological impairments in the lower limb rehabilitation training (LLRT). The RGT provides three active degrees of freedom (DoF) to both legs that are used to implement the gait cycle in such a way that the natural gait is not significantly affected. The robot consists of (i) the partial body weight support (PBWS) system to assist patients in sit-to-stand transfer via the precision linear rail system and (ii) the bipedal end-effector (BE) to control the motions of lower limbs via two mechanical arms. The robot stands out for multiple modes of training and optimized functional design to improve the quality of life for those patients. To analyze the performance of the RGT, the kinematic and static models are established in this paper. After that, the reachable workspace and motion trajectory are analyzed to cover the motion requirements and implement natural gait cycle. The preliminary results demonstrate the usability of the robot.

Dual mutation (MTHFR A1298C with PAI (4G) mutation) manifesting with bilateral lower limb gangrene in a neonate

2021 ◽  
Vol 14 (1) ◽  
pp. e237340
Author(s):  
Ashutosh Kumar ◽  
Sateesh Ramachandran ◽  
Pranati Swain ◽  
Vandana Negi
Keyword(s):  
Lower Limb ◽  
Methylenetetrahydrofolate Reductase ◽  
Plasminogen Activator Inhibitor ◽  
Lower Limbs ◽  
Homozygous Mutation ◽  
Single Mutation ◽  
Prothrombotic State ◽  
Life Threatening ◽  
Bilateral Lower Limb ◽  
The Individual

Neonates are at highest risk of thrombosis among paediatric patients. The relative prothrombotic state in a well neonate is compensated by other factors preventing spontaneous thrombosis; however, in a neonate with genetic predisposition, the balance is tilted predisposing them to a life-threatening thrombotic episode. We describe a rare case of methylenetetrahydrofolate reductase A1298C (homozygous) mutation along with plasminogen activator inhibitor (4G) mutation in a neonate who developed bilateral lower limb gangrene following thrombosis of the iliac vessels without any triggering factor. The neonate underwent thrombectomy as debulking measure along with thrombolytic therapy followed by unfractionated heparin and low-molecular-weight heparin which is still being continued along with oral aspirin. The neonate had to undergo amputation of both the involved lower limbs in view of dry gangrene. This case highlights that the dual mutations causing the prothrombotic state predispose the individual to the spontaneous life-threatening thrombotic episode as compared with the single mutation.

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