Adaptive controller for omni-directional walker: Improvement of dynamic model

Mathematical Problems in Engineering

Karimi

2014

Self Cite

The problem of robust reliable tracking control on the omnidirectional rehabilitative training walker is examined. The new nonlinear redundant input method is proposed when one wheel actuator fault occurs. The aim of the study is to design an asymptotically stable controller that can guarantee the safety of the user and ensure tracking on a training path planned by a physical therapist. The redundant degrees of freedom safety control and the asymptotically zero state detectable concept of the walker are presented, the model of redundant degree is constructed, and the property of center of gravity constant shift is obtained. A controller that can satisfy asymptotic stability is obtained using a common Lyapunov function for admissible uncertainties resulting from an actuator fault. Simulation results confirm the effectiveness of the proposed method and verify that the walker can provide safe sequential motion when one wheel actuator is at fault.

Section: Redundant Input Model Of the Omnidirectional Walkermentioning

confidence: 99%

Robust Redundant Input Reliable Tracking Control for Omnidirectional Rehabilitative Training Walker

Sun

Mathematical Problems in Engineering

Karimi

2014

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“…In this section, an adaptive controller is proposed to control the ODW accurately following the reference path to deal with load change and COG shift [3]. …”

Section: Adaptive Congtrollermentioning

confidence: 99%

“…So the accuracy of the path tracking needs to be improved to ensure the users accurately following the exercise programs prescribed by the physical therapists. In previous studies, a nonlinear adaptive controller was developed to deal with load change and COG shift caused by the users, considering a center dynamic model [3]. The path tracking accuracy can be improved by adjust the parameters of adaptive controller.…”

mentioning

confidence: 99%

An improved adaptive controller with parameter optimization by GA for an omni-directional walker

Tan

Ishida

The 6th International Conference on Soft Computing and Intelligent Systems, and the 13th International Symposium on Advanced In

et al. 2012

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An omni-directional walker (ODW) has been developed for walking rehabilitation for people with walking disabilities. In rehabilitation, a user needs to accurately follow the reference path stored in the ODW in order to obtain good training effect. In order to improve the path tracking accuracy, a nonlinear adaptive controller was developed in pervious studies, to deal with load change and center of gravity shift caused by the user. The path tracking accuracy can be improved by adjust the parameter of the adaptive controller. In this paper, genetic algorithm is used to automatically and quickly optimize the parameters of adaptive controller. Simulation was conducted, in which the ODW was controlled to follow a linear path. The results were shown that the parameter optimization strategy is effective to quickly find the optimal parameter.

“…So the motors provided the same force when the different weight patients trained using the walker. Adaptive control method for the omnidirectional walker is discussed in [11][12][13], the kinetics equation was improved by considering the centerof-gravity shifts and load changes caused by users. The adaptive controller had obtained favourable tracking effect.…”

Section: Introductionmentioning

confidence: 99%

Improvement model for omnidirectional rehabilitative training walker and tracking control

Sun

2014 IEEE International Conference on Mechatronics and Automation

2014

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This paper is concerned with the problem of improvement model for the omnidirectional rehabilitative training walker and tracking control. The aim of the study is to obtain a model that closes to actual walker by considering motor rotation character. An asymptotically stable controller was gotten that can ensure tracking on a training path planned by a physical therapist. The controller that can satisfy asymptotic stability is obtained by constructing the Lyapunov function. The simulation results confirm the feasibility and effectiveness of the designed scheme and indicate the walker can ensure tracking motion by using the improved model.Index Terms -omnidirectional rehabilitative training walker, tracking control, improvement model, asymptotical stability