Research On Force/Position Compliance Control Of Industrial Robot Based On Dynamic Parameter Identification

With the continuous in-depth exploration of robotic application field,the interactive scenes used by robots become more and more abundant and complex.The classical impedance control mode can achieve the dynamic balance between end force and end position while considering both end force and end position tracking control.In classical impedance control mode,impedance parameters are invariable when facing sudden change of position or rigidity of external environment.In order to ensure steady-state force tracking in complex interactive scenes,a method of force compliance control based on fuzzy adaptive impedance is proposed in this paper.The aim is to show compliance characteristics according to the changing trend of external environment,actively respond to sudden changes and disturbances of external environment and timely make corresponding compensation measures to ensure product quality and consistency in grinding and polishing applications.The main research contents include:The XB4 robot was analyzed in forward kinematics and inverse kinematics,and simulated and tested based on the MATLAB simulation mechanism.The dynamic model of the robot is based on the Newton Euler method.A more detailed description of the dynamic properties of the robot,a linear friction compensation dynamic model is introduced.A dynamic feed-forward trajectory tracking controller is proposed based on the dynamic model,and its stability is verified using Lyapunov functions.In order to identify dynamic parameters of XB4 robot,a parameter normalization method is introduced in the process of obtaining the base parameter set,which can effectively avoid the error caused by the great difference of magnitudes between adjacent parameters.Select the fifth order Fourier series as the excitation path to determine the optimal excitation path for the finite term Fourier series with actual physical constraints and nonlinear optimization functions.The current data of joint encoder and motor are collected and converted into joint rotation angle and joint torque information.It is taken into the parameter identification block diagram to obtain the dynamic parameters of each joint.To verify the identified dynamic parameters above,a comparison experiment between calculated and simulated torques is established.The results show that the calculated torque of the identified dynamic parameters has the same trend as that of the simulation experiment,which means that the identified dynamic parameters conform to the dynamic characteristics of the real machine.In order to study the impact of different impedance parameters on system stability,a force flexible control method based on fuzzy adaptive control is proposed.Simulink block diagram is established in Matlab to analyze the effect of constant force,sine force and position tracking under this control method,and a force level compliance control platform is built.Two grinding conditions,plane and surface,are designed to verify the effectiveness of force level compliance control based on fuzzy adaptive control.