Research On Teaching By Demonstration Technology For Cooperative Manipulator Using Variable Impedance Based On SEMG

Compared with traditional industrial robots,the human-robot cooperative robot has good autonomy and flexible operating performance,and can complete complex tasks with human.For the flexible operation task,the simple trajectory teaching can not meet the demand of impedance change.In this subject,the end-point impedance model of the human arm is built on the basis of human arm s EMG information.Based on this model,the estimation of the impedance changes during the human-robot cooperation process is mapped to the variable impedance gain of the manipulator's impedance controller.In order to improve the performance of complex and flexible tasks,human-robot cooperation is achieved through the joint control of trajectory and impedance parameters which learning from human tutor.Firstly,kinematics analysis of iiwa human-machine cooperation robot is carried out.The D-H method is used to establish the coordinate system of the robot links,and the forward kinematics equation of the robot is derived according to the coordinate transformation matrix,and the Jacobi matrix is derived by differential transformation.The inverse Jacobian matrix is used to transform the velocity of Cartesian space into the joint space,thus the inverse kinematics of the robot is calculated.The MATLAB Robotic toolbox is used to establish the virtual simulation environment where can carry out the kinematics simulation verification.The workspace of iiwa robot is evaluated to provide a theoretical basis for the workable space in the process of human-robot cooperation.Secondly,the impedance estimation of human upper limb based on s EMG is studied.The stiffness model of the upper limb was established to analyze the stiffness and orientation of the upper limb.On the basis of the collection and preprocessing of surface EMG signal,the stiffness estimation model of the upper limb based on s EMG is established.Through the experiment,two model parameters of the end force mapping T_F and the force mapped zero space EMG signal are mapped to the end stiffness of the upper extremity to establish the arm terminal stiffness model based on the s EMG information.Thirdly,the research of variable impedance control based on s EMG is carried out.The variable impedance control architecture based on s EMG and the parameter mapping criterion are established.According to the physical and mathematical models of human-robot interaction impedance,the influence of impedance parameters for the control performance is simulated and analyzed;the research of gravity compensation and filtering algorithm based on force signal was finished;theperformance of force servo and the s EMG based variable impedance controller were verificated experimental.The experiment lays the foundation for the next step of human-robot cooperation flexible teaching experiment on the basis of s EMG signal.Finally,the variable impedance human-robot cooperation experimental platform is built,including the hardware and software systems.Two typical experiments are designed for the complex trajectory tracking experiment and the flexible operation reiteration experiment.The feasibility of the variable impedance human-robot cooperation arm impedance teaching based on s EMG information propose here is verified and its performance is evaluated.