Abstract:

In order to enhance the automatic emergency collision avoidance ability of intelligent vehicle under extreme working conditions， an integrated control method combined braking and steering is proposed. Firstly， an 18 degrees?of?freedom （DOF） unified dynamic model including the coupling characteristics of steering， braking and suspension subsystems is established， on which a braking on curve simulation is conducted on a level road. Then an overall framework of automatic emergency collision avoidance system combining braking and steering is put forward， in which a fifth?order polynomial programming algorithm is used for path planning， and a sliding mode tracking control is adopted for longitudinal movement while an optimal four?wheel steering tracking control based on two DOF reference model is used for lateral movement. Finally， taking the international standard on double lane change maneuver test under extreme condition as reference， a driving scene of automatic emergency collision avoidance is constructed， and a comparative simulation on above?mentioned 18 DOF model with automatic emergency steering collision avoidance and combined braking and steering collision avoidance at different speeds is carried out. The results show that when the vehicle speed is relatively high， the real trace has a certain lag relative to the ideal trace， and in extreme condition， the collision avoidance is hard to succeed only by steering maneuver， while the combined braking and steering collision avoidance system can further enhance the automatic emergency collision avoidance ability of vehicle in extreme condition， with the maximum passing speed increasing from 50 to 60 km/h.

Key words: intelligent vehicle, extreme condition, automatic emergency collision avoidance, combination control