Research On Active Compliant Control Strategy For Robotic Assembly Base On Force Feedback

As an indispensable part of industrial production,assembly is also the most labor-intensive part.But the existing assembly robots have the disadvantages of poor adaptability and low efficiency.It is of great significance to improve the intelligent level of assembly robot for the realization of "Made in China 2025".In this paper,IRB1200 robot with F/T sensor is used as the experimental platform to study the path planning,active compliance control and gravity compensation of F/T sensor.In the aspect of robot path planning,an algorithm based on improved artificial potential field method and fast extended random tree fusion is proposed in this paper.Firstly,the gravitational potential field function is modified by adding floating control points and fixed control points to the robot model.In the repulsion potential field function,the relative distance from the target point is increased,and the adjustment factor is introduced to realize the potential field regulation,so that the robot can move towards the target while avoiding obstacles.Secondly,in order to solve the problem that potential field method is easy to fall into local minimum,the idea of gravity is introduced in the extension stage of random tree to make robot move towards the target and jump out of local minimum.Finally,the simulation experiment is carried out by using MATLAB,which proved that the algorithm can meet the requirements of robots for path planning in the workspace.Research on robotic adaptive control algorithm.In this paper,the mathematical model of shaft-hole contact is established.The measurements of the sensor are converted into the actual contact force,and the impedance control based on the end force feedback is carried out.And Simulink is used to build the simulation model of the robot impedance control system.In order to obtain the appropriate impedance parameters,the parameter identification experiment is carried out by using the control variable method.For the uncertain environment,we design a new adaptive impedance controller.The experimental results show that the system has better dynamic performance and steady-state performance when dealing with environmental changes after adding the adaptive impedance controller.Because the pose of the robot changes continuously during the assembly process,the zero value of the sensor changes.At the same time,the measurements of the sensor will change due to the influence of gravity,which will have a great impact on the subsequent control algorithm.To solve this problem,a gravity compensation system is designed in this paper.The system corrects the reference values of the sensor in different poses to ensure that the force measurements are consistent.And the experiment of the robot following the external force is carried out to verify the effectiveness of the gravity compensation system.Finally,the robotic shaft-hole assembly experiment is carried out.The assembly process is divided into three stages.The mechanical analysis is carried out for each stage,and the corresponding pose adjustment control algorithm is proposed.