Research On Compliance Control Of Cooperative Robot Based On Force/Position Double Feedback

Most traditional industrial robots only have position control and can not show flexibility when contacting with the outside world.They usually have to work away from the crowd.The cooperative robot can realize compliance control,ensure the safe interaction between human and robot,and then cooperate with operators to complete some complex and changeable tasks.In this paper,Ta6-r5 robot equipped with joint torque sensor is taken as the research object,and the absolute encoder and joint torque sensor are used as joint position feedback and force feedback.The design and verification of impedance controller based on force position double feedback and the characteristics of impedance parameters are carried out.Among them,the position control of the operation space in the compliance control is transferred to the joint space through kinematics,and the absolute value encoder in the joint module is used as the position feedback to control the rotation of the motor to realize the position control.For the perception of contact force in impedance model,the joint force is obtained by joint torque sensor and calculated by heavy torque compensation.Mainly completed the following work:(1)The improved DH method is used for kinematics modeling and trajectory planning of the robot,and the functional relationship between the end motion of the operation space and the joint motion of the joint space is established.It provides a solution to the rotation of robot joint motor for the end motion control in impedance model.The dynamic model of the robot is established by Lagrange method.The compensation torque of gravity term is obtained,and combined with the force feedback signal of joint torque sensor,the actual contact force of input impedance model is solved.(2)The impedance control method is analyzed,and the robot position impedance control method based on joint force position feedback information is studied.The causes of machine human tracking error under this control method are deduced theoretically,and an adaptive impedance control method is further designed for this reason.The force tracking simulation of adaptive impedance control is completed by MATLAB/Simulink.(3)The compliance control experiment based on force position double feedback is carried out to verify the control method designed in this paper,and other implementation methods are used as a control.The experimental contents are traction force,impedance parameter influence analysis and plane constant force grinding experiment.The experimental results show that the compliance control method of cooperative robot based on force position double feedback is feasible,and the influence of impedance parameters on the control system is analyzed.