Static-dynamic analysis of a lower limb exoskeleton controlled by a fuzzy PD

2021 ◽

Vol 51 ◽

pp. 77-94

Author(s):

Olurotimi A. Adeleye ◽

Tamunomiete S. Ekine ◽

Ahmed A. Yinusa

Keyword(s):

Dynamic Analysis ◽

Lower Limb ◽

Nonlinear Dynamic ◽

Differential Transform Method ◽

Transform Method ◽

Positive Direction ◽

Lower Limb Exoskeleton ◽

Applied Torque ◽

Differential Transform ◽

And Control

In this study, the nonlinear dynamic analysis of the motion and control of the lower limb exoskeleton using differential transform method is presented. Devices for medical processes are continuously undergoing improvement such as enhancing and assisting automatic therapies with flexible and configurable programs for treating people with partial disability in lower limbs as applied in lower-limb exoskeleton. The configurable programs in this exoskeleton can be applied to observe and control the motion of the exoskeleton for effective physiotherapy and reduced rehabilitation time for patients with such disability. Hence, a two degree of freedom nonlinear dynamic model for the motion and control of the lower limb exoskeletons was developed for two links. The nonlinear dynamic models are solved by applying the differential transform method (DTM) and verified with the forth order Runge-Kutta numerical method (RK4). The effects of the applied torque on the two links are investigated and it is observed that Link 1 has large negative deflection amplitude that drives link 2 towards the opposite positive direction. An increase in the applied torque resulted in increase in the amplitude of the system for all initial condition considered. This in turns increases the nonlinear dynamic behavior of link 2 due to its lower mass value. The speed of both links dampens out over the history due to the presence of damping term. At equilibrium, both links are in phase and have the same amplitude over the time history. This study provides an analytical tool for observing and controlling the motions of the lower limb exoskeleton and for improving the designs of the medical device.

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Design of Lower Limb Exoskeleton using Gearbox for Rehabilitation of Paralyzed Patients

International Journal of Engineering and Advanced Technology - Regular Issue ◽

10.35940/ijeat.e9338.069520 ◽

2020 ◽

Vol 9 (5) ◽

pp. 112-115

Keyword(s):

Dynamic Analysis ◽

Lower Limb ◽

Mechanical Design ◽

Design Procedure ◽

Primary Analysis ◽

Static And Dynamic Analysis ◽

Lower Limb Exoskeleton ◽

Standard Design ◽

Cord Injury ◽

Paralyzed Patient

The number of people with mobility disorder cause by stroke spinal cord injury or related disease is increasing rapidly.To improve quality of life of this people device that can assist them to regain the ability to work are of great demand. Robotic devices are generally used for purpose.The aim of this paper is to present the design and analysis of lower limb exoskeletons.The Exoskeleton is designed by Mechanical Design Procedure for linkages and against the Position values obtained from Gait Analysis.The Gearbox is designed using standard design procedure. This exoskeleton work on the principle of robotics by using sensors, actuator like DC motor. Gait analysis is used as a primary analysis followed by static and dynamic analysis of designed model.Static and Dynamic Analysis is performed in ANSYS Workbench. This exoskeleton will be used for paralyzed patient (paraplegia)as well as for the people who have had accidents for lower body.The limitation of this work is the same exoskeleton cannot be used for all person and a small defect in sensor and other electronic devices will stop the exoskeleton. Using this exoskeleton a paralyzed patient will be able to rehabilitate they will be able to perform stand to sit motion.

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Preliminary design and development of a low-cost lower-limb exoskeleton system for paediatric rehabilitation

Proceedings of the Institution of Mechanical Engineers Part H Journal of Engineering in Medicine ◽

10.1177/0954411921994940 ◽

2021 ◽

pp. 095441192199494

Author(s):

Jyotindra Narayan ◽

Santosha Kumar Dwivedy

Keyword(s):

Dynamic Analysis ◽

Lower Limb ◽

Low Cost ◽

Coupled System ◽

Contact Forces ◽

Lagrange Principle ◽

Element Analysis ◽

Lower Limb Exoskeleton ◽

Simulation Results ◽

Paediatric Rehabilitation

In this work, the design, modeling, and development of a low-cost lower limb exoskeleton (LLES) system are presented for paediatric rehabilitation (age: 8–12 years, mass: 25–40 kg, height: 115–125 cm). The exoskeleton system, having three degrees-of-freedom (DOFs) for each limb, is designed in the SolidWorks software. A wheel support module is introduced in the design to ensure the user’s stability and safety. The finite element analysis of the hip joint connector along with the wheel support module is realized for maximum loading conditions. The holding torque capacity of exoskeleton joints is estimated using an affordable spring-based experimental setup. A working prototype of the LLES is developed with holding torque rated actuators. Thereafter, the dynamic analysis for the human-exoskeleton coupled system is carried out using the Euler-Lagrange principle and SimMechanics model. The simulation results of estimating joint actuator torques are obtained for two paraplegic subjects (Case I: 10 years age, 30 kg mass, 120 cm height and Case II: 12 years age, 40 kg mass, 125 cm height). The details of input parameters such as body mass, link lengths, joint angles, and contact forces are discussed. The simulation results of dynamic analysis have shown the potential of estimating the torques of joint actuators for the developed prototype during motion assistance and gait rehabilitation.

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