| The vehicle steering system is critical to the handling stability, initiative security, and comfort of the vehicle. Electric power steering (EPS) is a new technology of automotive power steering, which can be used to save fuel, improve initiative security, control the steering feel, and protect the environment. This technology meets the demand to electronicalize and intelligentize modern vehicles, and it has become the research focus of the power steering technology. Based on EPS dynamic model, the assist characteristics, steering compliance, and driving feel of EPS system are analyzed in present study; furthermore, three transfer functions -- , and are proposed as the quantitive indexes. After the analysis on the stability of the system, the actuator assist torque-speed requirements and assist stiffness-inertia requirements have been generated. They are served as theoretical basis for the parameter and control strategy of EPS system.The present paper analyzes the effect of EPS on steering performance. The new system of evaluation includes steering maneuverability, steering returnability, on-center handling performance, steering hand-wheel vibration, servo motion sensitivity and assist characteristics. Some relevant evaluation indexes are also discussed here. The results will shed light on the design of EPS system and criteria of related experiments.Based on Robust control method, uncertain factors and disturbance are effectively restricted by H_infinity optimal controller. In this way, the goal of system control has been achieved. In order to make the system more stable, assist strategy and returnability strategy are also studied in this paper. The present paper proposes an efficient design method of EPS system. With the technology of hardware-in-the-loop, virtual design and driver-vehicle-environment closed loop simulation based on virtual reality, we can effectively shorten the design period and save cost, as well as meet the system performance requirements.
|
PDF Full Text Request