Abstract:

 An active control method of steering-by-wire (SBW) was proposed based on a fractional-order proportional-integral-differential (PID) theory to have a better vehicle running stability. The authors stablished a Simulink dynamic model of the SBW system, and designed a control strategy of state-tracking-correction with yaw-rate-feedback using an ideal variable transmission ratio curve with constant yaw rate gain. Some rationalization and parameter tuning were processed out by using an Oustaloup filter and a particle swarm optimization algorithm. The automobile SBW with a fractional-order PID controller was analyzed by an off-line simulation using a Carsim/Simulink joint simulation under the conditions of high-speed double-shift line and the conditions of fish hook. The results show that the fractional order PID controller reduces the yaw angular velocity by 4.7% and 9%, reduces the lateral acceleration by 6.3% and 7.7%, and reduces the sideslip angle of center of mass by 9.8% and 19.5%, compared with the traditional PID control and with the fuzzy control. Therefore, the controller has better SBW active control performance.

Key words:  vehicle driving stability , active-control , steer-by-wire (SBW) , variable ratio ,  proportion integration differentiation (PID) ,  fractional-order PID , particle swarm optimization