Abstract
Keywords:
EPS-TT (Electric Power Steering – Two Transmission), Torque Sensor, Uni-directional Motor, assist torque, PID (Proportional-Integral-Differential) Control
Abstract
In this study, a new column type electric power steering system (EPS-TT) is developed and evaluated. The remarkable features of this EPS-TT are opto-isolated torque sensor and assist torque control methodology, which uses a uni-directional motor and two clutches. Thus it does not require a complicated motor drive system that consumes a large amount of electrical energy when the direction of rotation is reversed. This allows the new system to use a smaller and simpler assist motor. A numerical model of EPS-TT is developed. In addition a map-based control method and a PID control algorithm are designed to control the EPS-TT. Various steering inputs and driving conditions are applied to the system and the resulting performance is analyzed. The results show that numerical results are good accordance with experimental results. However, the yaw rates and lateral accelerations differed slightly, because the numerical model does not consider the dynamics of the rack, tie rod, tires, and so on. A map-based motor controller is as effective as a PID controller and do not detract from the stability or controllability of the vehicle. The performance achieved by the EPS-TT is similar to that of a conventional EPS across the frequency domain and under various steering input. Thus, EPS-TT can replace the conventional EPS with cheap product cost and simple construction.