Research On The Compliant Human-machine Interface Mechanism For Exoskeletons

With the social development,number of patients with lower limb motor dysfunction caused by various factors is increasing.Meanwhile,with the improvement of living standard and the development of medical technology,Population aging has become increasingly prominent.Due to the limited mobility of paraplegic patients and the elderly,exoskeleton robots satisfy their needs in supporting rehabilitation training and improving living capacity.Straps are commonly used to connect human with the exoskeleton at this stage,which makes the human body in a state of over-constraint relative to the exoskeleton.Because of the unavoidable joint misalignment between the human body and the exoskeleton,it can only rely on deformations of human tissue and straps to try to make up.This is bound to produce a greater binding in the human-machine interface,as well as discomfort to the wearer,and even cause secondary injury to patients.In view of the present problem,this paper has carried on the research on the compliant human-machine interface(HMI)mechanism for exoskeletons,in order to adapt to joint misalignment and different individuals effectively and improve wearing comfort.This research is supported by National Natural Science Fund of "Research on the Principle and Realization of Compliant Human-Machine Interface Mechanism for Exoskeletons".Main contents are as follows:(1)Biomechanical model of lower limbs and design of compliant HMI mechanism.We proposed a constraint principle of compliant HMI mechanism and completed the specific structure design based on the analysis of Biomechanical model of lower limbs,combined with the existing configuration of exoskeketon robot.We completed the prototype production of compliant HMI mechanism after parts processing and assembly.(2)Mechanical and simulation analysis of rigid-flexible coupling models of both HMI systems.We established rigid-flexible coupling models of both human-machine interface systems respectively,based on the deformations of the human body and straps in the HMI system with straps and the concrete constraints in the compliant HMI system.Results show that the compliant HMI mechanism can effectively reduce the human-machine interaction forces,especially the direction of shank,decreased by 80%and above.The effect of human-machine interaction forces reduction is more obvious with the greater joint misalignment.(3)Research on wearing comfort evaluation model of exoskeletons.A partial wearing comfort evaluation model of objective comfort score was proposed with human-machine interaction forces.Based on the AHP analytic hierarchy process theory,the partial wearing comfort was integrated according to the weight vectors.Finally,the overall comfort evaluation models of two kinds of HMI mechanisms were established by human-machine interaction forces.(4)Experimental research on compliant HMI mechanism.A comparative experiment system was established.Studies of the human body follower experiments and the experimental studies on wearing comfort and individual adaptability were carried out respectively.The experimental results show that the average wearing comfort of compliant HMI mechanism is about 50%higher than that of HMI mechanism with straps,while the human body has better movement followability eelative to exoskeleton robot.This paper presented a compliant HMI mechanism and establisheed a wearing comfort evaluation model based on the human-machine interaction forces.It is proved that the compliant HMI mechanism can improve the wearing comfort and adapt to different individuals under the premise of ensuring that the human body can follow the good movement of the exoskeleton robot.