Research On The Complaint Robust Control Of Industrial Assembly Robot

Industrial assemble robots usually work in the constrainted environment and contact with the assembly components,the assembling work process of the robots highly depends on the complaint control of the end-effector.Meanwhile,the accurate tracking control trajectory is very important to precisely finish the assembling work in the conditions of parametric variations and uncertain nonlinearities.However,the current complaint impedance control algorithm mainly aims at the contact force control after the robot end-effector contacts with the assembling environment.It cannot meet the desired requirements of the impedance control because it doesn't include the special design of the impedance.The current research on the trajectory tracking control of industrial robots pays little attention to various disturbances and parametric uncertainties,also does not include the influence of variable load and the collisions between the robots and the environment in the assembling process.Some disturbances such as the dynamic couplings among the joints of the robots and the variable link parameters are also not taken into consideration in the current control design.This dissertation focuses on the complaint impedance control and assembly trajectory tracking control of the industrial assembly robots when working in the assembly process.The main contributions are listed as follows.(1)The dynamic characteristics of the 6 degree of freedom Mitsubishi assembly robots is investigated.The relationship between the control inputs and the velocity,accelerated velocity of the robot joint angles are gained.The dynamic equation is solved by the Lagrange method.The Denavit-Hartenberg method is applied to develop the forward and backward kinetic equations of motion arm in the industrial assembling robots.(2)A dynamic complaint control strategy is proposed in the dissertation.Different from the pure trajectory tracking control or the impedance control among the parts during the assembling operations,the proposed complaint control method applies the sliding mode control algorithm to design the corresponding trajectory control law and uses the impedance filter to obtain the desired assembling trajectory according to the desired contact force.Meanwhile,an external dynamic parametric identification method is used to obtain the necessary matrices and constants online.The robust sliding mode control method has been verified to have relatively high accuracy through comparative simulation results based on the robot experimental platform.The results show that the method can not only achieve the trajectory tracking with high accuracy,but also can shift to the contact force control adaptively with high complaint contact force.(3)Taking the influence of the external disturbances and parametric uncertainties during the assembling process into account,a robust sling mode tracking controller and an adaptive robust controller with disturbance adaptions are designed.The controllers are designed to adaptively address the parametric perturbations and disturbances during the assembling operations and hence to enhance the robustness against the external disturbances and parameter variations.The two designed controllers can enable the industrial robots to normally work in the conditions of large parameter uncertainties and external disturbances.The effectiveness and performances of the proposed controllers have been validated based on the comparative simulation results in the robotic platform.(4)An intelligent robotic experimental platform is established,which consists of automatic conveyor,positioning device,infrared switch,parallel robot,SCARA robot,AGV trolley and the Mitsubishi assembling robots.The research objective is chosen as the 6 DOF Mitsubishi assembling robot and a gripper for the robotic end-effector is designed to grasp and assemble the inner spring mechanism for the air switches.The design procedure is achieved by using a general and scientific method called the axiomatic design theory.