Research On Trajectory Tracking And Vibration Suppression Of Vehicle Hydraulic Flexible Manipulator

With the rapid development of science and technology,the robotic arm technology,especially the on-board robotic arm,has achieved unprecedented development.As an efficient,stable and safe transfer machine,the on-board robotic arm has been widely used in various engineering fields.While the demand for vehicle-mounted robotic arms and the requirements for its performance are gradually increasing simultaneously,so the research on the vehicle arm is of great practical significance.Therefore,this paper focus on trajectory tracking and vibration suppression for on-board hydraulic flexible manipulators:First,I have divided the system into two subsystems: the robotic arm system and the hydraulic servo system.Since the third link is a flexible link,the dynamic model of the robotic arm subsystem is established by using the assumption mode method and Lagrange principle.And then established the dynamic model of hydraulic cylinder based on the principle of hydraulic servo system.Finally,the complete dynamic model of the whole system is established by the Jacobin matrix of the two subsystems.Finally,the buffeting problem is solved by using the saturation function instead of the symbolic function,but the saturation function is not a continuous function to suppress the buffeting effect,which is not as good as the hyperbolic tangent function instead of the symbolic function.The saturation function and hyperbolic tangent function are used to replace the sign function to suppress chattering respectively.The simulation results show that the designed controller is effective.Second,based on the complete dynamic model of the vehicle hydraulic flexible manipulator,a controller based on the integral sliding mode variable structure has been proposed in the view of the joint trajectory tracking and vibration problem of the vehicle hydraulic flexible manipulator.It is proved that the system is asymptotically stable through the Lyapunov stability principle.Moreover,the integral term of initial state variables can weaken chattering and reduce steady-state error in the proposed algorithm.However,the cumulative effect will appear in the integral term.When the initial state is relatively larger,the system will be saturated with the actuator,so the hyperbolic tangent function is used to solve the actuator saturation.Finally,the saturation function is used instead of the symbolic function to solve the chattering problem.The simulation results show that the designed controller is effective.Third,considering the uncertainties,unmodeled dynamics and external disturbances in the system,a sliding mode controller according to the improved exponential convergence law is designed based on the complete dynamic model of the system.The second-order sliding surfaces which has good vibration suppression effect is selected as the switching surfaces of the system,and the general exponential convergence law has been improved,which can not only improve the approaching speed,but also solve the high frequency buffeting problem.The simulation results show that the tracking of the joint trajectory and the suppression of buffeting are good,and the buffeting can be effectively suppressed.At the same time,comparing the improved exponential convergence law with the improved exponential approach law on the control input current simulation,the improved exponential convergence law can be more effective to suppress the buffeting,and the effectiveness of the proposed control method has been verified.Finally,we summarize the research contents and look forward to the future.