Turning at high speed, doing sharp turning at low speed, and
doing parking are three critical motions of a vehicle needed to be
considered. This research studied dynamic characteristics of a
multi-function four-wheel steering system that could improve
directional stability of vehicles on turning at high speed,
minimize radius of turning of vehicles while doing sharp turning at
low speed, and reduce spaces needed on parking motion.
Four methods were used to study dynamics characteristics of a
multi-function four-wheel steering system. Those four methods were
method of constant yaw rate, method of equal side slip angle,
method of zero side slip, and method of negative side slip or
controlling side slip angle.
The results of the study show that the method of zero side slip
is the best method to determine rear wheel angle needed for a
vehicle doing parking motion in order to minimize radius of turn.
When a vehicle is turning at high or medium speed, rear wheel angle
needed should be determined by method of negative side slip
angle.
A multi-function, four-wheel steering system could improve
directional stability, sharp turning performance, and parking
performance of a vehicle.