Research On Tracking Control Method Of Cushion Service Robot

With the anabatic aging population and the increase of the patients with lower limb paralysis,to solve their movement problem inside the house,cushion robot is applied.Because the cushion robot is utilized in a narrow and complicated environment,it must accurately accomplish the trajectory tracking in order to avoid repetitive drives and ensure the safety of the user.The movement velocity of cushion robot at work may be too large or change abruptly,considering the security of users,it is of vital importance to limit its velocity.However,the constraint on the velocity and the parameter uncertainty and unknown disturbance existing in the robot system may cause the decline of tracking performance.In this case,it is crucial to design a controller which can improve the tracking precision for the robot trajectory tracking.On basis of the backstepping control theory,in this thesis,the design methods of the controller used to improve tracking precision are researched,the main contents are as follows.Based on the dynamics model of cushion robot,the controller with compensation term and speed constraint is put forward by adopting backstepping control theory.Through the real-time compensation for trajectory tracking error and velocity tracking error,the trajectory tracking within safe velocity range is realized.On basis of the Lyapunov stability principle,the asymptotic stability of the system is proved and the validity of the designed method is verified by the simulation results.In addition,the controller without compensation term is designed.The simulations under the conditions of regular speed and speed constraint are carried out.Through comparing the simulation results,it can show the importance of the velocity constraints and the necessity of compensation term.On account of the parameter uncertainties and external disturbances in the system,the design process of the backstepping robust controller for n order strict feedback nonlinear system is presented and the stability proof is proceeded.As for cushion robot,a novel backstepping robust controller is designed.The backstepping controller can guarantee the global asymptotic stability of the system.At the same time,the robust controller can estimate the parameters and eliminate the unknown disturbance.The simulation results show that the novel backstepping robust controller can make the system own better robustness and the effectiveness and feasibility of the controller design method is verified.