Asymmetric Cooperation Control of Dual-Arm Exoskeletons Using Human Collaborative Manipulation Models

The exoskeleton is mainly used by subjects who suffer muscle injury to enhance motor ability in the daily life environment. Previous research seldom considers extending human collaboration skills to human–robot collaborations. In this article, two models, that is: 1) the following the better model and 2) the interpersonal goal integration model, are designed to facilitate the human–human collaborative manipulation in tracking a moving target. Integrated with dual-arm exoskeletons, these two models can enable the robot to successfully perform target tracking with two human partners. Specifically, the manipulation workspace of the human–exoskeleton system is divided into a human region and a robot region. In the human region, the human acts as the leader during cooperation, while, in the robot region, the robot takes the leading role. A novel region-based Barrier Lyapunov function (BLF) is then designed to handle the change of leader roles between the human and the robot and ensures the operation within the constrained human and robot regions when driving the dual-arm exoskeleton to track the moving target. The designed adaptive controller ensures the convergence of tracking errors in the presence of region switches. Experiments are performed on the dual-arm robotic exoskeleton for the subject with muscle damage or some degree of motor dysfunctions to evaluate the proposed controller in tracking a moving target, and the experimental results demonstrate the effectiveness of the developed control.

I. Introduction

Currently, stroke and various diseases cause limb movement disorders, which is becoming a leading cause of adult disability [1]. High-intensity and task-specific upper limb treatment consists of active and highly repetitive movements, which is considered to be one of the most effective approaches to arm and hand function restoration [2]. However, traditional methods from therapists are far from being able to complete such rehabilitation training, which, in turn, affects motor task performance, even further leading to the impaired arm motor function. Robot exoskeletons-supported training is emerging as a solution to aid the subjects who suffer muscle injury by providing high-intensity, repetitive, and task-specific treatment to enhance motor ability in the daily life environment, which has become a research hotspot.