scholarly journals Evaluation of Physical Interaction during Walker-Assisted Gait with the AGoRA Walker: Strategies Based on Virtual Mechanical Stiffness

Sensors ◽  
2021 ◽  
Vol 21 (9) ◽  
pp. 3242
Author(s):  
Sergio D. Sierra M ◽  
Marcela Múnera ◽  
Thomas Provot ◽  
Maxime Bourgain ◽  
Carlos A. Cifuentes
Keyword(s):  
Interaction Force ◽  
Gait Pattern ◽  
Lower Limbs ◽  
Human Gait ◽  
Physical Interaction ◽  
Mechanical Stiffness ◽  
High Stiffness ◽  
Clinical Scenarios ◽  
Analysis Laboratory ◽  
Smart Walker

Smart walkers are commonly used as potential gait assistance devices, to provide physical and cognitive assistance within rehabilitation and clinical scenarios. To understand such rehabilitation processes, several biomechanical studies have been conducted to assess human gait with passive and active walkers. Several sessions were conducted with 11 healthy volunteers to assess three interaction strategies based on passive, low and high mechanical stiffness values on the AGoRA Smart Walker. The trials were carried out in a motion analysis laboratory. Kinematic data were also collected from the smart walker sensory interface. The interaction force between users and the device was recorded. The force required under passive and low stiffness modes was 56.66% and 67.48% smaller than the high stiffness mode, respectively. An increase of 17.03% for the hip range of motion, as well as the highest trunk’s inclination, were obtained under the resistive mode, suggesting a compensating motion to exert a higher impulse force on the device. Kinematic and physical interaction data suggested that the high stiffness mode significantly affected the users’ gait pattern. Results suggested that users compensated their kinematics, tilting their trunk and lower limbs to exert higher impulse forces on the device.

scholarly journals Human Gait Cycle Analysis Using Kinect V2 Sensor

2020 ◽  
Vol 15 (3) ◽  
pp. 3-14
Author(s):  
Péter Müller ◽  
Ádám Schiffer
Keyword(s):  
Gait Cycle ◽  
Medical Condition ◽  
Measurement Data ◽  
Human Movement ◽  
Gait Pattern ◽  
Lower Limbs ◽  
Human Gait ◽  
Skeleton Model ◽  
Kinect V2 ◽  
Reduced Mobility

Examining a human movement can provide a wealth of information about a patient’s medical condition. The examination process can be used to diagnose abnormal changes (lesions), ability development and monitor the rehabilitation process of people with reduced mobility. There are several approaches to monitor people, among other things with sensors and various imaging and processing devices. In this case a Kinect V2 sensor and a self-developed LabView based application was used, to examine the movement of the lower limbs. The ideal gait pattern was recorded in the RoboGait training machine and the measured data was used to identify the phases of the human gait. During the evaluation, the position of the skeleton model, the associated body joints and angles can be calculated. The pre-recorded ideal and natural gait cycle can be compared.With the self-developed method the pre-recorded ideal and natural gait cycle can be compared and processed for further evaluation. The evaluated measurement data confirm that a reliable and mobile solution for gait analysis has been created.

scholarly journals Amble Gait EEG Points at Complementary Cortical Networks Underlying Stereotypic Multi-Limb Co-ordination

2021 ◽  
Vol 15 ◽  
Author(s):  
Joyce B. Weersink ◽  
Natasha M. Maurits ◽  
Bauke M. de Jong
Keyword(s):  
Lower Limb ◽  
Primary Motor Cortex ◽  
Right Hemisphere ◽  
Gait Pattern ◽  
Lower Limbs ◽  
Human Gait ◽  
Hemisphere Dominance ◽  
The Right ◽  
Spectral Perturbation ◽  
Healthy Participants

BackgroundWalking is characterized by stable antiphase relations between upper and lower limb movements. Such bilateral rhythmic movement patterns are neuronally generated at levels of the spinal cord and brain stem, that are strongly interconnected with cortical circuitries, including the Supplementary Motor Area (SMA).ObjectiveTo explore cerebral activity associated with multi-limb phase relations in human gait by manipulating mutual attunement of the upper and lower limb antiphase patterns.MethodsCortical activity and gait were assessed by ambulant EEG, accelerometers and videorecordings in 35 healthy participants walking normally and 19 healthy participants walking in amble gait, where upper limbs moved in-phase with the lower limbs. Power changes across the EEG frequency spectrum were assessed by Event Related Spectral Perturbation analysis and gait analysis was performed.ResultsAmble gait was associated with enhanced Event Related Desynchronization (ERD) prior to and during especially the left swing phase and reduced Event Related Synchronization (ERS) at final swing phases. ERD enhancement was most pronounced over the putative right premotor, right primary motor and right parietal cortex, indicating involvement of higher-order organization and somatosensory guidance in the production of this more complex gait pattern, with an apparent right hemisphere dominance. The diminished within-step ERD/ERS pattern in amble gait, also over the SMA, suggests that this gait pattern is more stride driven instead of step driven.ConclusionIncreased four-limb phase complexity recruits distributed networks upstream of the primary motor cortex, primarily lateralized in the right hemisphere. Similar parietal-premotor involvement has been described to compensate impaired SMA function in Parkinson’s disease bimanual antiphase movement, indicating a role as cortical support regions.

Kinematic Coordination in Human Gait: Relation to Mechanical Energy Cost

1998 ◽  
Vol 79 (4) ◽  
pp. 2155-2170 ◽  
Author(s):  
L. Bianchi ◽  
D. Angelini ◽  
G. P. Orani ◽  
F. Lacquaniti
Keyword(s):  
Energy Expenditure ◽  
Energy Cost ◽  
Time Course ◽  
Sagittal Plane ◽  
Dimensional Space ◽  
Mechanical Energy ◽  
Direction Cosine ◽  
Lower Limbs ◽  
Human Gait ◽  
Plane Orientation

Bianchi, L., D. Angelini, G. P. Orani, and F. Lacquaniti. Kinematic coordination in human gait: relation to mechanical energy cost. J. Neurophysiol. 79: 2155–2170, 1998. Twenty-four subjects walked at different, freely chosen speeds ( V) ranging from 0.4 to 2.6 m s−1, while the motion and the ground reaction forces were recorded in three-dimensional space. We considered the time course of the changes of the angles of elevation of the trunk, pelvis, thigh, shank, and foot in the sagittal plane. These angles specify the orientation of each segment with respect to the vertical and to the direction of forward progression. The changes of the trunk and pelvis angles are of limited amplitude and reflect the dynamics of both right and left lower limbs. The changes of the thigh, shank, and foot elevation are ample, and they are coupled tightly among each other. When these angles are plotted one versus the others, they describe regular loops constrained on a plane. The plane of angular covariation rotates, slightly but systematically, along the long axis of the gait loop with increasing V. The rotation, quantified by the change of the direction cosine of the normal to the plane with the thigh axis ( u 3 t ), is related to a progressive phase shift between the foot elevation and the shank elevation with increasing V. As a next step in the analysis, we computed the mass-specific mean absolute power ( P u ) to obtain a global estimate of the rate at which mechanical work is performed during the gait cycle. When plotted on logarithmic coordinates, P u increases linearly with V. The slope of this relationship varies considerably across subjects, spanning a threefold range. We found that, at any given V > 1 m s−1, the value of the plane orientation ( u 3 t ) is correlated with the corresponding value of the net mechanical power ( P u ). On the average, the progressive rotation of the plane with increasing V is associated with a reduction of the increment of P u that would occur if u 3 t remained constant at the value characteristic of low V. The specific orientation of the plane at any given speed is not the same in all subjects, but there is an orderly shift of the plane orientation that correlates with the net power expended by each subject. In general, smaller values of u 3 t tend to be associated with smaller values of P u and vice versa. We conclude that the parametric tuning of the plane of angular covariation is a reliable predictor of the mechanical energy expenditure of each subject and could be used by the nervous system for limiting the overall energy expenditure.

Mechanical properties of cat soleus muscle elicited by sequential ramp stretches: implications for control of muscle

1993 ◽  
Vol 70 (3) ◽  
pp. 997-1008 ◽  
Author(s):  
D. C. Lin ◽  
W. Z. Rymer
Keyword(s):  
Soleus Muscle ◽  
Constant Velocity ◽  
Short Range ◽  
Single Pulse ◽  
Fold Increase ◽  
Elastic Behavior ◽  
Time Interval ◽  
Mechanical Stiffness ◽  
Initial Portion ◽  
High Stiffness

1. Force changes in areflexive cat soleus muscle in decerebrate cats were recorded in response to two sequential constant velocity (ramp) stretches, separated by a variable time interval during which the length was held constant. Initial (i.e., prestretch) background force was generated by activating the crossed-extension reflex, and stretch reflexes were eliminated by section of ipsilateral dorsal roots. 2. For the initial 400-900 microns of the first stretch, the muscle exhibited high stiffness, classically termed "short-range stiffness." This high stiffness region was followed by an abrupt reduction in stiffness, called muscle "yield," after which force remained at a relatively constant level, achieving a plateau in force. This plateau force level depended largely on stretch velocity, but this dependence was much less than proportional to the increase in stretch velocity, in that a 10-fold increase in velocity produced < 2-fold increase in plateau force. 3. In experiments where the velocities of the two sequential ramp stretches were identical, the force plateau level was the same for each stretch, regardless of the time elapsed before the second stretch (varied from 0 to 500 ms). In contrast, measures of stiffness during the initial portion of the second stretch showed time-dependent magnitude reductions. However, stiffness recovered quickly after the first stretch was completed, returning to control values within 30-40 ms. 4. In one preparation, in which the velocities of the two sequential ramp stretches were different, the force plateau elicited during the second stretch exhibited velocity dependence comparable with that recorded in the earlier single velocity studies. Furthermore, muscle yield was still evident in the case where the force change was due solely to the change in velocity and where short-range stiffness had not yet recovered fully from the initial stretch. On the basis of these findings, we argue that the classical descriptions of short-range stiffness and yield are inadequate and that the change in force that has typically been called the muscle yield reflects a transition between short-range, transient elastic behavior to steady-state, essentially viscous behavior. 5. To examine changes in the muscle's mechanical stiffness during single ramp stretches, a single pulse perturbation was superimposed at various times before, during, and subsequent to the constant velocity stretch. The force increment elicited in response to each pulse decreased relative to the initial isometric value, remained essentially constant until the end of the ramp, and then returned to its prestretch magnitude shortly (30-40 ms) after stretch termination.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Biomechanical parameters characterising the foot during normal gait

2021 ◽  
Vol 21 (2) ◽  
pp. 87-104
Author(s):  
Arina SEUL ◽  
Aura MIHAI ◽  
Antonela CURTEZA ◽  
Mariana COSTEA ◽  
Bogdan SÂRGHIE
Keyword(s):  
Neuromuscular Control ◽  
Gait Pattern ◽  
Biomechanical Analysis ◽  
Human Gait ◽  
Foot Health ◽  
Mean Values ◽  
Study Results ◽  
Size Groups ◽  
Biomechanical Parameters ◽  
Extended Group

The biomechanical analysis allows to understand the normal and pathological gait, the mechanics of neuromuscular control, and last but not least, allows the visualisation of the effects of footwear on human gait or feet. Biomechanical analyses are very important for the footwear development process, as they can identify the incorrect loading of the foot or the incorrect gait pattern, thus avoiding the occurrence of deformations. This paper aims to create an average representative model of barefoot loading based on an extended group of participants by applying an optimal procedure for measuring biomechanical parameters. The variation of four basic biomechanical parameters, namely force, pressure, contact time and contact area, was measured using a pressure platform and a specialised software system. The data was collected from 32 healthy females, without particularities regarding foot health and the practice of performance sports, aged between 18 and 30 years, divided into three size groups – 36, 37 and 38. The T-Student test was applied to verify if there are significant differences between the left and right foot. Statistical indicators for each parameter were calculated, in order to characterize and establish the degree of variation of the obtained values, as follows: mean, standard deviation, minimum and maximum values, the amplitude of variation and coefficient of variation (CV). The study results confirm that the obtained mean values can be used as input data to load the foot and perform virtual simulations of footwear products.

scholarly journals Neuromechanical adaptations of foot function to changes in surface stiffness during hopping

2021 ◽  
Author(s):  
Jonathon V. Birch ◽  
Luke A. Kelly ◽  
Andrew G. Cresswell ◽  
Sharon J. Dixon ◽  
Dominic J. Farris
Keyword(s):  
Muscle Activation ◽  
Center Of Mass ◽  
Lower Limbs ◽  
Foot And Ankle ◽  
High Stiffness ◽  
Movement Strategies ◽  
Compliant Surfaces ◽  
Foot Function ◽  
Intrinsic Muscles ◽  
Ankle Mechanics

Humans choose work-minimizing movement strategies when interacting with compliant surfaces. Our ankles are credited with stiffening our lower limbs and maintaining the excursion of our body's center of mass on a range of surface stiffnesses. We may also be able to stiffen our feet through an active contribution from our plantar intrinsic muscles (PIMs) on such surfaces. However, traditional modelling of the ankle joint has masked this contribution. We compared foot and ankle mechanics and muscle activation on Low, Medium and High stiffness surfaces during bilateral hopping using a traditional and anatomical ankle model. The traditional ankle model overestimated work and underestimated quasi-stiffness compared to the anatomical model. Hopping on a low stiffness surface resulted in less longitudinal arch compression with respect to the high stiffness surface. However, because midfoot torque was also reduced, midfoot quasi-stiffness remained unchanged. We observed lower activation of the PIMs, soleus and tibialis anterior on the low and medium stiffness conditions, which paralleled the pattern we saw in the work performed by the foot and ankle. Rather than performing unnecessary work, participants altered their landing posture to harness the energy stored by the sprung surface in the low and medium conditions. These findings highlight our preference to minimize mechanical work when transitioning to compliant surfaces and highlight the importance of considering the foot as an active, multi-articular, part of the human leg.

Application of Floquet Theory to Human Gait Kinematics and Dynamics

2021 ◽  
pp. 1-35
Author(s):  
Sandesh G. Bhat ◽  
Susheelkumar Cherangara Subramanian ◽  
Thomas S Sugar ◽  
Sangram Redkar
Keyword(s):  
Floquet Theory ◽  
Gait Pattern ◽  
Human Gait ◽  
Reduced Order ◽  
Oscillator System ◽  
Walking Gait ◽  
Gait Kinematics ◽  
Dimension Analysis ◽  
Time Trace ◽  
Original Domain

Abstract In this work, the lower extremity physiological parameters are recorded during normal walking gait, and the dynamical systems theory is applied towards its stability analysis. The human walking gait pattern of kinematic and dynamical data is approximated to periodic behavior. The embedding dimension analysis of the kinematic variable's time trace and use of Taken's theorem allows us to compute a reduced-order time series that retains the essential dynamics. In conjunction with Floquet Theory, this approach can help study the system's stability characteristics. The Lyapunov-Floquet (L-F) Transformation application results in constructing an invariant manifold resembling the form of a simple oscillator system. It is also demonstrated that the simple oscillator system, when re-mapped back to the original domain, reproduces the original system's time evolution (hip angle or knee angle, for example). A re-initialization procedure is suggested that improves the accuracy between the processed data and actual data. The theoretical framework proposed in this work is validated with the experiments using a motion capture system.

MECHANICAL STIFFNESS OF MAN'S LOWER LIMBS

1964 ◽  
Author(s):  
Arthur E. Hirsch ◽  
Leonard A. White
Keyword(s):  
Lower Limbs ◽  
Mechanical Stiffness

Modeling a Predictive Control of Human Locomotion Based on the Dynamic Behavior

2018 ◽  
pp. 316-331
Author(s):  
Joao Mauricio Rosario ◽  
Leonimer Flavio de Melo ◽  
Didier Dumur ◽  
Maria Makarov ◽  
Jessica Fernanda Pereira Zamaia ◽  
...  
Keyword(s):  
Dynamic Behavior ◽  
Predictive Control ◽  
Lower Limb ◽  
Center Of Mass ◽  
Human Locomotion ◽  
Lower Limbs ◽  
Human Gait ◽  
Virtual Model ◽  
Dynamical Study ◽  
Continuous Dynamic

This chapter presents the development of a lower limb orthosis based on the continuous dynamic behavior and on the events presented on the human locomotion, when the legs alternate between different functions. A computational model was developed to approach the different functioning models related to the bipedal anthropomorphic gait. Lagrange modeling was used for events modeling the non-holonomic dynamics of the system. This chapter combines the comparison of the use of the predictive control based on dynamical study and the decoupling of the dynamical model, with auxiliary parallelograms, for locating the center of mass of the mechanism using springs in order to achieve the balancing of each leg. Virtual model was implemented and its kinematic and dynamic motion analyzed through simulation of an exoskeleton, aimed at lower limbs, for training and rehabilitation of the human gait, in which the dynamic model of anthropomorphic mechanism and predictive control architecture with robust control is already developed.

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