Invariant Manifolds in Human Joint Angle Analysis During Walking Gait

2021 ◽  
Author(s):  
Sandesh Bhat ◽  
Sangram Redkar ◽  
Thomas G. Sugar
2021 ◽  
Author(s):  
Sandesh Bhat ◽  
Sangram Redkar ◽  
Thomas G. Sugar

Author(s):  
Sandesh G. Bhat ◽  
Thomas G. Sugar ◽  
Sangram Redkar

Abstract The complex dynamics of human gait is yet to be completely understood. Researchers have quantified stability of walking gait using Floquet multipliers as well as Lyapunov exponents. In this article, we utilize the techniques and tools from dynamical system theory and invariant manifolds to map the gait data onto a time invariant representation of a dynamical system. As an example, the complex behavior of the joint angle during walking was studied using a conformal mapping approach that transformed the time periodic system into a time invariant linear system. Time-delay embedding was used to reconstruct the dynamics of the original gait system with time series kinematic data. This minimal realization of the system was used to construct a Single Degree of Freedom (SDOF) oscillator. The time evolution of the linear oscillatory system was mapped back using the conformal mapping derived using Lyapunov-Floquet Theory. This algorithm was verified for walking gait kinematics data for two healthy human subjects. A comparison was drawn between the phase space behavior of the original time periodic system and the remapped time invariant system. The two systems showed good correlation. The algorithm resulted in a well correlated phase space representation.


2021 ◽  
Author(s):  
Rongguo Song ◽  
Zelong Hu ◽  
Shaoqiu Jiang ◽  
Li Ma ◽  
Qingsong Ai ◽  
...  

2017 ◽  
Vol 865 ◽  
pp. 547-553 ◽  
Author(s):  
Ji Hun Park

This paper presents a new computation method for human joint angle. A human structure is modelled as an articulated rigid body kinematics in single video stream. Every input image consists of a rotating articulated segment with a different 3D angle. Angle computation for a human joint is achieved by several steps. First we compute internal as well as external parameters of a camera using feature points of fixed environment using nonlinear programming. We set an image as a reference image frame for 3D scene analysis for a rotating articulated segment. Then we compute angles of rotation and a center of rotation of the segment for each input frames using corresponding feature points as well as computed camera parameters using nonlinear programming. With computed angles of rotation and a center of rotation, we can perform volumetric reconstruction of an articulated human body in 3D. Basic idea for volumetric reconstruction is regarding separate 3D reconstruction for each articulated body segment. Volume reconstruction in 3D for a rotating segment is done by modifying transformation relation of world-to-camera to adjust an angle of rotation of a rotated segment as if there were no rotation for the segment. Our experimental results for a single rotating segment show our method works well.


2020 ◽  
Vol 32 (5) ◽  
pp. 863-875
Author(s):  
Seigo Kimura ◽  
Ryuji Suzuki ◽  
Katsuki Machida ◽  
Rie Nishihama ◽  
Manabu Okui ◽  
...  

In recent years, the burden per worker has increased due to a decrease in the working population. Wearable assist suits have been developed as one of the methods for solving the problem. To extend the assist suit to practical situations, it is necessary to provide a motion judgment interface for judging the motion of a wearer. Therefore, in our study, a motion judgment algorithm is proposed for assist suits, based on variable viscoelasticity. The proposed algorithm judges sitting, standing-up, stance, sitting-down, and gait using only the joint angle information of the suit and verification is performed using human joint angles obtained by motion capture. Thus, the motion judgment rate is 90% or more for sitting, standing-up, stance, and sitting-down, and 80% or more for gait, confirming the usefulness of motion judgment. Additionally, based on these results, further verification is performed on an actual machine. As a result, in a series of motions starting from the sitting to the standing-up, the stance, and the gait, the motion judgement is successful five times from the sitting to the standing-up, the stance, and once in gait. In a series of motions from sitting to standing-up, the stance, and sitting-down, the motion judgment is successful five times during sitting; five times during sitting, stance, and sitting-down; and three times during standing-up. In this way, it is confirmed that the proposed method can judge the motion only by angle information, although there is a problem in a success rate depending on the motion.


Author(s):  
Alastair B. During ◽  
Sudesh Sivarasu ◽  
George Vicatos

A-priori research show that trans-tibial (TT) amputees display poor gait parameters when walking with passive mechanical ankle-foot prosthetics (AFP’s). This has large implications for the amputee populations in the developing world, who have limited access to advanced prosthetic technologies and instead rely on baseline AFP’s. Analysis of such baseline AFP’s in literature indicates that the predominant issue with these devices are their inability to adequately replicate the mechanics of a normal ankle during the stance phase of a walking gait cycle. This has shown to be a contributory cause of increased energy expenditure, as well as secondary complications such as osteoarthritis and joint deterioration. This paper presents the design and analysis of a modular low-cost ankle-joint prosthetic (AJP) that serves as an attachment to existing prosthetic feet, with the intention to improve the ankle mechanics thereof. The AJP is modelled to reproduce ankle joint mechanisms, specifically controlled relative angular flexion in the sagittal plane, using only simple mechanical elements (i.e. compression springs instead of electronics). Initial results were positive, indicating that the AJP improves the stance phase mechanics of the baseline AFP in a simulated TT amputee gait cycle. During forefoot dorsiflexion rollover, an 80%–132% (p < 0.001) increase in joint angle and a 42–56% decrease in ankle stiffness (p < 0.001 for all but one participant) is observed. Following heelstrike a 22%–77% (p < 0.001) increase in joint angle is observed. However equipment and methodology errors left the moment response of this phase unverifiable. The overall conclusion of this paper is that the introduction of the AJP to baseline AFP’s supplies evidence of improved rollover shapes, easier phase transitions, and the facilitation of footflat during mid-stance.


2013 ◽  
Vol 52 (12) ◽  
pp. 126106 ◽  
Author(s):  
Ana S. Silva ◽  
André Catarino ◽  
Miguel V. Correia ◽  
Orlando Frazão

Author(s):  
Han-Byeol Oh ◽  
Ji-Sun Kim ◽  
A-Hee Kim ◽  
Bong-Jun Goh ◽  
Jun-Sik Kim ◽  
...  
Keyword(s):  

2018 ◽  
Vol 30 (8) ◽  
pp. 1787
Author(s):  
Sang-Ho Han ◽  
Mun-Ho Ryu ◽  
Je-Nam Kim

2019 ◽  
Vol 69 (3) ◽  
pp. 293-306
Author(s):  
Rui Zhang ◽  
Dianlei Han ◽  
Qiaoli Ji ◽  
Guoyu Li ◽  
Xian Li ◽  
...  

Abstract When studying the gait of pheasants, an intermittent-flight bird, it is necessary to take into account changes in the gaits and hindlimb joint angles resulting from increases of speed. In this study, pheasant locomotion postures were recorded on a speed-variable treadmill with high-speed cameras. Firstly, kinematic analysis showed that the stride cycle of pheasants decreased and the stride length increased with increasing speed. The duty factor also decreased, but was less than 0.5 in only about 10% of measurements. Thus, pheasants are more inclined to choose the grounded running or walking gait in laboratory situations. Secondly, changes in the tarsometatarso-phalangeal joint angle and the intertarsal joint angle at touch-down, mid-stance and lift-off concomitant with speed variation were studied. Tarsometatarso-phalangeal joint angle was found not to be significantly affected by changes in speed, but changed over larger ranges than the intertarsal joint angle. Thirdly, the continuous changes in the joint angles were studied during a complete stride cycle. The curves shifted leftward with increasing speed. Finally, the changes at four main positions were analyzed with increasing speed.


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