Research On External Force Estimation And Force Drag Control Of The Industrial Robot

Most of the traditional industrial robots only have the ability of position control,and the completion of tasks such as grinding and assembly in contact with working parts is low,and it is difficult to participate in human-robot collaborative work,which makes it difficult for robots to be further applied.Therefore,based on the identification of the robot model,the design of the external torque observer,and the admittance control,this paper studies the flexible drag control method of the industrial robot.This paper takes the ER3A-C60 six-degree-of-freedom robot as an example,and conducts research from the following parts:In order to improve the accuracy of robot dynamics identification,this paper proposes an improved identification method that can improve the identification accuracy of joint friction and reduce the influence of noise on experimental data.The method firstly processes the experimental data by iterative weighted least squares method,thereby reducing the heteroscedasticity of noise and improving the robustness of identification results.By adding physical feasibility constraints,the identified parameters have real physical meaning,which is more convenient for upper-layer applications.At the same time,the friction identification of each joint is carried out using the Stribeck friction model.In order to realize sensorless external torque estimation,an external torque estimation algorithm based on robot dynamics model is proposed in this paper.The method starts from the identified dynamic model,and then constructs a generalized proportional-integral disturbance observer(GPIO),so as to realize the effective observation of the time-varying external torque.Simulation and experimental results show that the method has higher estimation accuracy and better dynamic performance than the traditional extended state observer(ESO).In order to realize the fast and compliant drag of the robot,a sensorless force drag control algorithm based on the external torque observer and terminal sliding mode control is proposed in this paper.The method first obtains the accurate external torque signal through the GPIO observer,then designs the admittance controller to convert the force offset into the position offset,and finally realizes the position servo control under the action of the non-singular terminal sliding mode controller.Then a smooth drag effect is achieved.The simulation and experimental results show that the drag control algorithm can well realize the human-robot cooperative control.