Dynamic Modeling And Control Strategy Of A Planar Cable-Driven Parallel Robot

At present,the main cleaning schemes for side walls of large buildings are manual suspension scrubbing,wall-attaching scrubbing robot and rail scrubbing.These cleaning methods are slow,high cost and dangerous.In order to improve these shortcomings,this paper studied a four-cable planar driven parallel robot with lower risk factor,higher speed and more efficiency,and lower cost.The kinematics,dynamics and control strategy of the robot are studied.Firstly,the displacement,velocity and acceleration of the flexible parallel robot are analyzed,and the dynamic characteristics of the rope and pulley are analyzed.The inverse kinematics model of the robot is established by vector closure method.According to the practical application,two kinds of configuration of flexible parallel robot for robot are proposed.The simulation analysis of the two configurations shows that the vertical pulley configuration is better than the horizontal pulley configuration.According to the basic definition of stiffness,the inherent stiffness matrix and the controllable stiffness matrix of the system are established.The overall stiffness matrix of the system is obtained by combining the inherent stiffness and the controllable stiffness.A optimization method of cable tension based on the stiffness matrix is proposed through the principle of zero space.The dynamic model of the driving system is established considering the motor's inertia,viscous friction and Coulomb friction.The dynamic model of the moving platform is obtained by Newton-Euler method,and the overall dynamic equation of the system is obtained.According to the established general dynamic equation,the differential equation is solved by Runge-Kutta method,the pseudo-inverse of the structural matrix is solved by Gauss elimination method,and the actual tension of the flexible cable is obtained by the established tension optimization method.The results show that the simplified dynamic model is consistent with the simulation results in Admas and can accurately describe the dynamic characteristics of the flexible connecting rod.The dynamic model is decomposed into linear regression matrix and adaptive parameters.The sliding surface is selected according to the law of equal velocity reaching.The control law is established based on sliding mode control theory.The stability of the system is analyzed by Lyapunov's second method.The force control law of the system is established by the proposed tension optimization method,and the system dynamics and tension controller are obtained.Simulink simulation results show that the proposed control strategy can track trajectory and improve the stiffness performance of the moving platform.The inverse kinematics solution and dynamic model experiment of the planar four-rope parallel robot with vertical pulley configuration were carried out.The camera was calibrated according to the traditional calibration method,and the camera internal parameters matrix was obtained.The image pixel coordinates were transformed into world physical coordinates through the camera internal parameters matrix.The experimental results show that the kinematics and dynamics experimental results are basically consistent with the model.