Research On Adaptive Impedance Control Of Polishing Robot Based On Active Compliant Flange

The compliance of a robot is reflected in its adaptability when it comes into contact with the outside environment,which can help people complete many complicated tasks,including assembling,deburring,polishing and so on.This paper focuses on the compliant control of polishing robots.The polishing normal force has a great influence on the surface processing quality of the workpiece,this paper takes the constant force control of the polishing normal force as the starting point to study the contact force control of the robot polishing.First,this paper designs a flange-shaped pneumatic polishing mechanism held by the end of the robot called active compliant flange,based on polishing processing requirements.The mathematical model of its various parts is established,the nonlinear pneumatic flange model is linearized.Then,calculating the various parts of the active compliant flange,the transfer function of the flange system is obtained and the stability of the system is analyzed.Then,in robot feed motion control,the robot coordinate system is established and the positive and negative solution expressions of robot kinematics are obtained.In this paper,the robot's trajectory planning problem is deeply studied by referring to CNC Milling Method.The workpiece is polished by using the direction-parallel method.The mathematical expression for robot's polishing trajectory is obtained,then conduct a simulation study,and solutions to problems which probably arise during problemsolving process are given.Next,as for the contact force control of the robot,impedance control is used.A control model based on impedance control is firstly established.The influence of impedance parameters on the system is further studied by identifying impedance parameters through simulation,and theoretically study the steady-state error.To overcome insufficient of impedance control,according to Lyapunov's asymptotic stability theorem,an adaptive impedance control algorithm is proposed,the expression of adaptive control is given and its adaptability to environmental changes is also studied through simulation.Finally,a robotic polishing experiment platform based on active compliant flange is built and the workpiece is polished with an adaptive impedance control strategy.Many experiments are performed to verify the feasibility and robustness of the algorithm.