Study On The Control System Of A Multi-DoF Lower Extremity Exoskeleton

The Lower Extremity Exoskeleton (LEE) is a kind of equipment that can be integrated with human for assisting their walking. Owing to the special object of service, it entails higher capability of the control system than that of the usual machine.In this paper, based on the comprehensive investigation of the movement mechanism of human lower limb, a scheme that employs ten motors each of which resembles one critical joint of human lower limb is presented for the sake of making the exoskeleton capable of approximating the actual gait of human at upmost and, consequently, being efficient and effective in implementation.Having sufficiently considered the special requirement of the control system for Lower Extremity Exoskeleton (LEE), a hierarchical architecture of control system, of which several performance indexes are defined for evaluation of its viability, including the upper computerARM, the lower computer DSP and the protocol of CANopen for communication, is proposed for coordinated control of the Ten-DoF motor system. As the whole platform is established, more emphasis, in this paper, is then placed on the coordinated control of Ten-DoF motor system under the protocol of CANopen with the object of having the Lower ExtremityExoskeleton (LEE) moved precisely according to the predefined trajectory of gait. Wherein, the methodology of decomposition and modularization, namely that of dynamically allocating the email box available for communication among several modules, is employed for addressing the problem of inadequate capability of communication owing to the limitation of available email box, especially when ten motors should be controlled simultaneously under even one single DSP. In addition, a prototype of the Lower Extremity Exoskeleton (LEE) control system is established, and the coordinated control of Ten-DoF motor are carried out which demonstrate the feasibility of the control scheme based on DSP and the protocol of CANopen.