Research On Intelligent Assistance Method Of Nursing Robot In The Stand-to-sit Interaction

STS（Stand-to-sit interaction）refers to the process from stand to sit,and the interaction usually refers to the process of contact between the human body and the seat.STS is as easy and natural as breathing for normal people with healthy lower limbs,and they won’t perceive any obstacles.However,for those people with lower extremity disabilities or insufficient lower extremity muscle strength,they have certain obstacles in STS.When they perform STS,their lower extremity muscles couldn’t work properly,causing them to receive a violent shock from the seat after contacting the seat surface.Therefore,it is necessary to develop a assisted nursing robot helping them perform STS.In the development of the STS nursing robots,it is significant to analyze the human dynamics of the stand-to-sit interaction,aims to understand the force and motion mechanism,and guide the construction of the control strategy of the robot.STS can be divided into two sub-processes according to whether the body is in contact with the seat.This paper proposed a lumped parameter model with 9 degrees of freedom composed of three dimensions torsional,vertical,and horizontal to simulate the post-contact process of STS.The modeling process includes the simplification of human biological structure,the setting of lumped parameters,the modeling of horizontal dimension,the staged modeling of vertical dimension and the predictability analysis of vertical dimension model.This study verified the feasibility of the model in the torsional dimension by comparing the model-fitted thigh muscle force changes in STS with the muscle force transformed by the EMG signal.This study also verified the validity of the model in the vertical dimension by comparing the attitude information fitted by the model to that obtained through automatic dynamic analysis of mechanical systems（ADAMS）simulations.Based on the modeling of the human body,this study proposed an auxiliary model of the nursing robot,analyzed the task goals and specific processes of the intelligent assistance of the nursing robot and design an intelligent auxiliary control system for the nursing robot.Through the simulation experiment of the control system,the effectiveness of the intelligent assistance method of the nursing robot is verified.