Research on patients-passive control strategy of the rehabilitation exoskeleton based on NN-SMC

There are amounts of patients with locomotor dysfunction caused by stroke until now. Body weight supported treadmill training (BWSTT) has proved to be an efficient method of rehabilitation training for those people. The lower exoskeleton consists of two legs which is used to guide and assist motions of patients with the help of weight support devices and a treadmill. A prototype of the body weight support exoskeleton rehabilitation device (BWSERD) has been designed in this paper, which contains two pairs of direct drives at hip and knee joints. It has also four torque transducers and four encoders. In order to conduct the patients-passive rehabilitation training after stroke, a control strategy based on neuro network and sliding mode controller is developed. The effectiveness of the proposed method is confirmed by the simulation results.

Empowering lower limbs exoskeletons: state-of-the-art

SUMMARYGiven the advanced breakthroughs in the field of supportive robotic technologies, interest in the integration of the human body and a robot into a single system has rapidly increased. The aim of this work is to provide an overview of empowering lower limbs exoskeletons. Along with lower exoskeleton limbs, their unique design concepts, operator–exoskeleton interactions and control strategies are described. Although many problems have been solved in recent development, many challenges remain. Especially in the context of infantry soldiers, fire fighters and rescuers, the challenges of empowering exoskeletons are discussed, and improvements are outlined and described. This study is not only a summary of the current state, but also points to weaknesses of empowering lower limbs exoskeletons and outlines possible improvements.

BIO-BASED SUPERVISORY CONTROL OF A LOWER EXOSKELETON FOR STANCE PHASE

This paper presents a newly supervisory impedance control strategy of a wearable lower limb exoskeleton in stance phase intended to enhance human performance and support load-carrying using biomechanical analysis. In order to control the coupled human-robot system, the impedance control strategy, previously developed by the authors for swing phase, has been herein expanded up to the stance phase by regulating the desired impedance between the exoskeleton and a wearer's limb according to a specific motion speed. The effect of human behaviours on the change of impedance parameters across variable walking speeds in the stance phase is adopted to design the fuzzy rules for the control strategy. The control performance of the designed exoskeleton is evaluated on a bench-testing over different ranges of walking speeds (about 0.3 m/s to 1.2 m/s). Experimental results show that the resulting interaction torque, the human-exoskeleton tracking error, and electrical power consumption are significantly reduced as compared to a traditional impedance control, especially in the stance phase. Besides that, an average of 72.3 % of the load was transferred to the ground by the exoskeleton during the stance phase of walking. The developed control strategy on the lower exoskeleton has the potential to increase comfort and adaptation to users during daily use.