Research On Pitch And Roll Control Approach Of Vehicle Actvie Suspension System

The pitch and roll motion of vehicle could have a bad influence on ride comfort when vehicle travels on uneven roads. Therefore, this paper taking active suspension as the actuator, designs the control algorithm of active suspension to suppress the vehicle body’s pitch and roll motion. Considering the application of active suspension, this paper proposed the active suspension start-exit control strategy to reduce the energy consumption of active suspension and designs active suspension hardware controller.At first, in this paper, a 7-DOF vehicle model is established to express the pitch and roll motion of vehicle. Based on the model, a distributed model predictive control(DMPC) method for active suspension is proposed with the consideration of constraints of actuators’ outputs and the distributed architecture of active suspension system. This approach splits the high-dimensional vehicle system into 5 low-dimensional suspension control subsystems, and designs MPC controller for each suspension control subsystem individually. The simulation results show that the control algorithm that proposed by this paper can suppress the vehicle body’s pitch and roll motion effectively.In actual vehicle, some states are unmeasurable and active suspension has high energy consumption. To solve the two problems, this paper designs vehicle Kalman state estimator and active suspension start-exit control strategy. The Kalman state estimator can estimate the unmeasurable states. Analyzing the effects of vehicle pitch and roll motion on the ride comfort, the active suspension start-exit control strategy turns active suspension on or off. It can avoid the unnecessary work of active suspension, reduce the energy consumption.Finally, to apply the control algorithm and control strategy designed before in real system, a hardware controller of active suspension is designed. This paper adopts the method of modular design to design the hardware circuit and software system of active suspension hardware controller. According to the function requirement, the hardware circuit and software system are split into different function modules and designed individually. In order to verify the effectiveness of each function module of the designed active suspension controller, this paper finally carries out the hardware function test experiment based on AMESim simulation software and NI equipment. The experiment result indicates that the function of hardware controller meeting the expectations.