Research On Key Techniques Of Master-slave Massage System

With the development of China’s economy,people’s living standards are constantly improving,and they pay more attention to physical health.However,with the development of economy,the competition is increasingly fierce,the social rhythm is faster and faster,the exercise time of young people is gradually reducing,and the sedentary time in office is gradually increasing,which often leads to low back pain and even lumbar disc herniation.The elderly are prone to osteoporosis and often have low back pain.For low back pain,the most appropriate treatment is the physical therapy,and the most appropriate way in physical therapy is traditional Chinese massage.At present,the massage equipment developed by researchers at home and abroad is to set the program first and then perform the massage operation according to the program,which has poor flexibility.Therefore,this paper studies the master-slave massage system,which can make the massage operation more flexible.The master-slave control algorithm is studied,the advantages and disadvantages of joint space control,position space control and velocity space control are analyzed,and a hybrid master-slave control mode is designed for the master-slave system;The characteristics of position / force hybrid control mode and damping control mode with force feedback are analyzed.Because the admittance control mode in damping control mode does not need to establish the dynamisc model of slave and is easy to be realized,and the admittance control is adopted in the force feedback control.The hybrid master-slave admittance control mode is adopted by the system,the control block diagrams in the position control mode and velocity control mode are presented,and the admittance control laws corresponding to the position control mode and velocity control mode are deduced.The Chinese massage techniques are analyzed,and the Chinese pressing and Chinese pushing are selected as the experimental massage techniques,and the forces exerted in the two methods are analyzed.The theoretical analysis lays a theoretical foundation for the following experiments,and the selection of massage techniques provides a medical basis for the following experiments.A 6-DOF series master is developed independently.6 potentiometers are used to be the angle sensors,and the master circuit is established.The kinematics of the master is analyzed,and the position vector of the master end point is obtained.According to the control needs in velocity space,the master Jacobian matrix is obtained.The master developed provides a physical master for master-slave control experiments,the position vector of the master end point provides a theoretical basis for the subsequent master-slave control experiment in position space,and the Jacobian obtained provides a theoretical basis for the subsequent master-slave control experiment in velocity space.A 6-DOF parallel slave is designed.The slave is the Stewart structure,driven by 6 electric cylinders,and the power source of a electric cylinders is a stepping motor.The slave circuit is estabblished,and the 3D force sensor used by the slave is selected.The inverse kinematics of the slave is analyzed,the Jacobian of the slave is obtained,the actual cylinder speeds are obtained,and the pose iteration process of the main points in the velocity space control mode is given.According to the kinematics analysis results of the slave,the reachable workspace and flexible workspace of the slave are obtained.The slave designed provides the physical slave for the subsequent master-slave control experiments,the kinematic analysis provides the theoretical basis for the subsequent master-slave control experiments,and the workspace analysis provides the necessary data for the subsequent physical experiments.The semi-physical simulation platform is built,and the composition of the platform is described.The principles of master filtering,debouncing and scaling are explained.The master-slave simulation experiments in position space and velocity space with force feedback are carried out,the master-slave experiment of pressing a plane in position space with force feedback is carried out,and the master-slave experiment of pushing a plane in velocity space with force feedback is carried out.The master-slave simulation experiments in position space and velocity space without feedback prove the correctness of the kinematics algorithm.The master-slave simulation experiment of pressing a plane in position space with force feedback provides an algorithm basis for the subsequent master-slave physical experiment of pressing a plane in position space with force feedback;At the same time,the simulation process of force feedback gives the conclusion that the simulation experiment of force feedback can not be carried out on ordinary desktop computers.The physical experiment platform is built,the hardware equipment for communication between MATLAB and slave is selected,the hardware signal processing board of 3D force sensor is established,and the hardware components of the physical platform are described.The principle of slave limit is explained,and the filtering of 3D force sensor is carried out.Without considering the organization model,the physical experiments of master-slave control without force feedback are performed,and the master-slave control experiments of traditional Chinese pressing and pushing with force feedback using the admittance control are carried out,and the experimental results are analyzed.According to the comfort requirements of the patients,the mechanical model of human skin is established,the admittance control rate is modified,the physical experiment of traditional Chinese pushing considering the tissue model is carried out,and the experimental results are analyzed.The algorithm of physical experiments without considering the tissue model provides an algorithm basis for the physical experiment considering the tissue model,and it proves that the system can realize the simple physical experiments of traditional Chinese massage.To improve the massage comfort of the system,the mechanical characteristics of tissue are analyzed,the mechanical model of spring damping of skin and subcutaneous tissue are established,the model is calibrated,the formula for calculating the z-direction displacement correction using force error is given,the algorithm diagram under the condition of known tissue mechanical parameter is given,and the pushing physical experiment is carried out,and the experimental results show that the system can ensure better massage comfort.Aiming at the disadvantage that the algorithm needs to know the mechanical parameter of the system,two massage algorithms for estimating the mechanical parameters are proposed,the corresponding physical experiments are carried out,and the experimental results show that the algorithms are also practical.There are 148 figures,16 tables and 157 references in the paper.