Control system design of electric power steering for a full vehicle model with active stabilizer

In this paper, we designed a control system of an electric power steering (EPS) by considering an active stabilizer. A full vehicle simulation model with the active stabilizer is derived and used to design a controller of the EPS. Although controllers of the EPS are designed generally to obtain the steering feeling similar to a hydraulic power steering (HPS), it is difficult to obtain comfortable steering feeling on driving situations such as on a rough road. Therefore, we design a controller of the active stabilizer which can not only reduce the roll motion of a vehicle body but also suppress the self-aligning torque which acts on a steering axis through front tires on the rough road. The controller of the EPS is designed by applying a gain-scheduled control considering the self-aligning torque which acts on a steering axis from the front tires during driver's steering and a sensor torque on the steering axis. The control system of the EPS considering the active stabilizer is tuned according to a design strategy of the control system. It is verified that the proposed control system is effective to obtain the comfortable steering feeling similar to the HPS during the driver's steering and reduce the loads of both the driver's steering and the EPS during the rough road running.