Fuzzy cerebellar model articulation controller-based adaptive tracking control for load-carrying exoskeleton

Han Wu,Lin Lang,Hongxu Ma,Honglei An,Qing Wei

doi:10.1177/0020294020944962

Abstract

Load-carrying exoskeletons need to cope with load variations, outside disturbances, and other uncertainties. This paper proposes an adaptive trajectory tracking control scheme for the load-carrying exoskeleton. The method is mainly composed of a computed torque controller and a fuzzy cerebellar model articulation controller. The fuzzy cerebellar model articulation controller is used to approximate model inaccuracies and load variations, and the computed torque controller deals with tracking errors. Simulations of an exoskeleton in squatting movements with model parameter changes and load variations are carried out, respectively. The results show a precise tracking response and high uncertainties toleration of the proposed method.

Highlights

The exoskeleton is a kind of wearable and anthropomorphic device that enhances the physical capabilities of a non-disabled wearer.1,2 It looks like a humanoid robot or a part of that in appearance and is worn in parallel with human body in general
A trajectory tracking controller associated with fuzzy cerebellar model articulation controller (FCMAC) compensation for load-carrying exoskeleton in the stance phase is proposed in this paper
The control scheme is mainly composed of computed torque control (CTC) and FCMAC

Summary

Introduction

The exoskeleton is a kind of wearable and anthropomorphic device that enhances the physical capabilities of a non-disabled wearer. It looks like a humanoid robot or a part of that in appearance and is worn in parallel with human body in general. The exoskeleton developed by Massachusetts Institute of Technology (MIT) uses similar force control method under a state-machine control strategy with the support of plenty of sensor information.. The exoskeleton developed by Massachusetts Institute of Technology (MIT) uses similar force control method under a state-machine control strategy with the support of plenty of sensor information.13 Both of them showed wearer’s metabolism reduction during locomotion. Though much progress has been achieved in adaptive control of load-carrying exoskeleton, few works touch on the situation of a broad range of load mass and inertia variation, which is practically unavoidable. A computed torque control (CTC) associated with fuzzy cerebellar model articulation controller (FCMAC) method is proposed for loadcarrying exoskeleton on tracking problems. FCMAC is used to approximate modeling deviation, overcome parameter variations as well as represent the dynamic payload model. If the exoskeleton tracks the reference trajectory decided by the wearer well, the interaction force will be minimum, and that is what a load-carrying exoskeleton should achieve

Method

Findings

Conclusion