Compound control strategy for the pump-controlled-parallel-variable-displacement-motor speed system

Addressing the adaptive characteristics of the flow rate and the multiplying nonlinearity in the pump-controlled-parallel-variable-displacement-motor speed system, a kind of compound control architecture was proposed, in which the pressure is controlled by on the variable displacement pump and the rotational speed of each driving axle is controlled by variable displacement motor respectively. The 2-order linearized models of the pump-controlled-pressure-system and the motor-speed-control-system were derived. A pressure planning algorithm and a sliding mode control law were presented for the dynamic regulating of pressure. By means of introducing of the disturbance observer to the motor proportion integration differentiation controller, the nonlinear disturbance and unknown load disturbance can be restrained, so as to promote the steady precision under fluctuant pressure. The compound controller for a 1-pump-2-motor system of the transporter was designed. The simulation verifies validity of the proposed compound control strategy.