Sliding mode control of vehicle hydraulic travelling system based on exponential convergent disturbance observer

This paper takes the motor drive travelling system of vehicles as research object. Addressing the disturbance derived from complex pavement and nonlinearity of system during walking and combined the characteristics of the mathematical model of hydraulic travelling system, a disturbance observer based on exponential convergent is designed on the conditions of the vehicle drives at low speed. It can estimate disturbances online and feedforward compensate to the control system. Then a sliding mode control strategy is used to motor speed control system. The simulation model of valve controlled motor system is carried out through MATLAB/Simulink platform. Compared of the result between the proportion integral differential (PID), sliding mode control (SMC) and sliding mode control (SMC) + disturbance observer (DOB), the oscillation and overshoot of step response on SMC are decreased obviously. When the slow time-varying torque disturbance is added on to evaluate the effects of disturbance observer induced on the SMC, the disturbance value can estimate precisely and deduce influence of motor speed. It improves the SMC + DOB control accuracy and made the vehicle travel on the complex pavement more smoothly.