Research On Dynamics And Control Strategy Of Active Suspension Mobile Manipulator

Mobile manipulator robot is a working platform composed of mobile platform and manipulator.This kind of robot has good space maneuverability and motion flexibility,and is widely used in industrial production such as pipeline cleaning,self-assembly and national defense and military industry,and has broad application prospects.Therefore,it is of great practical significance to study the working stability of mobile manipulators.At present,many significant progress has been made in the research of mobile manipulator robots at home and abroad,and relevant control strategies have been developed.However,few studies have been carried out on the stability of mobile manipulators with controllable suspension.In the mobile manipulator robots studied in this paper,active suspension is proposed to replace the traditional hard-axle suspension in the mobile platform.Active suspension and manipulator constitute complete constraints to reduce disturbances caused by the movement of part of the manipulator and improve the stability and controllability of the mobile platform.In this paper,from the point of view of sliding mode control and fuzzy control,the dynamic model of mobile manipulator with active suspension is taken as the research object.Lyapunov method is used to verify the stability.Two high performance trajectory tracking controllers are proposed.The reliability of the new controller is verified by comparing with the simulation experiment of sliding mode controller with constant gain.The main contents are as follows:Firstly,the dynamic model of the mobile manipulator with active suspension is built,and the control force of the active suspension is taken into account to form a complete constrained dynamic equation,which is the basis of the controller design.Then,the sliding mode control theory is used to design the controller according to the coupling and uncertainty characteristics of the model.Firstly,a sliding mode-fuzzy control strategy based on upper bound estimation of uncertain information of the model is designed,which achieves fast convergence and reduces jitter through adaptive piecewise design of sliding mode gain.Fuzzy strategy is used to estimate the upper bound of uncertain information in piecewise sliding mode gain design,and the theoretical stability is verified by Lyapunov equation.The convergence and jitter reduction effect of this control strategy are very good,but it relies on the understanding of model precise data.Considering the cost of obtaining model precise parameters in practical engineering,the design is further considered.An efficient synovial controller is designed for the case of model uncertainties and missing information.Aiming at the problem of missing upper bound uncertain information,a sliding mode-fuzzy control strategy without upper bound information of model uncertainties is designed.The control strategy has the characteristics of reducing jitter and fast convergence.The sliding mode gain derivative is designed by segments,and the fuzzy strategy is used to adjust the gain according to the state of the sliding mode variable function and its derivative.This control strategy can make the sliding film variable converge to the sliding film plane at a higher speed when it is far from the sliding film surface.When it is near the sliding film plane,the fuzzy strategy is used to adapt according to the current state of the sliding film variable and its derivative state.By adjusting the gain derivative,the sliding variables are always smooth when they approach the synovial surface,thus reducing the jitter phenomenon.The theoretical stability is verified by Lyapunov equation.