Research On Modeling And Control Methods Of Three-Degree-of-Freedom Assisted Standing Mechanism

Difficulty in standing due to diseases or aging will lead to a decline in the quality of life.Assisted standing training can not only help users complete the standing process,but also exercise the user’s ability to stand independently.Applying robot technology to assisted standing training can effectively reduce the workload of rehabilitation physicians and improve the effect of rehabilitation training.In recent years,with the increasing demand for assistive standing equipment among people with standing difficulties,various assisted standing mechanisms have emerged.This paper focuses on the kinematics,dynamics and control of a three degree of freedom assisted standing mechanism.The specific research contents are as follows:(1)Analysis of the human standing process.Combined with domestic and foreign research results,the characteristics of the human standing process were analyzed,and combined with the limb characteristics of patients with difficulty in standing,a four-stage standing based on knee flexion is proposed,and the motion characteristics of different stages are analyzed.Through the experiment of the actual process of standing with knees bent,the characteristics of human motion in the four stages of standing are described.(2)Research on kinematics model of the assisted standing mechanism and the human-machine kinematics modeling.Through the analysis of the auxiliary standing process,the assisted standing mechanism is simplified in the sagittal plane,and the motion mapping relationship between the generalized coordinates of the assisted standing mechanisms and the driving variables is established.The structure of human body is simplified according to the characteristics of joint movement during the standing process,and the human-machine motion constraints are constructed according to the characteristics of human-machine cooperation standing,thus the human-machine cooperation kinematics model is established,and the accuracy of the kinematics model is verified through simulation.(3)Research on human-machine dynamics modeling of the assisted standing mechanism.The dynamic characteristics of the human standing process are analyzed,and the dynamic model of the human-machine system assisted standing process is established by using the Lagrange method.Based on the human-machine kinematics model,the mapping relationship between the driving force of the assisted standing mechanism and the human joint angle was constructed,and the validity of the model was verified through joint simulation.(4)Research on active and passive control algorithms of the assisted standing mechanisms.According to the motion characteristics and structural characteristics of the mechanism,the controlled object of the assisted standing mechanisms is designed,and a PID controller is optimized by using the fuzzy control principle;based on the generalized coordinate characteristics of the assisted standing mechanisms,the motion state of the human body is described,and the human-machine interaction force is used as the input information to identify the human standing intention.Based on this,the active control method of the auxiliary standing mechanism based on the finite state machine is established.Finally,a standing-up experimental platform is designed and built,and the effectiveness of the algorithm is verified through experiments.