The present invention involves a method of controlling a vehicle
steer-by-wire system having two independent road wheels. In one
embodiment, the method comprises providing a steering wheel control
sub-system to generate road wheel reference angles and to produce steering
feel for a vehicle driver. The method further includes providing a road
wheel control sub-system including a multivariable road wheel controlled
plant and a multivariable-road wheel controller for controlling actual
road wheel angles to track to road wheel reference angles within a servo
control system structure having road wheel angular position feedback and
road wheel angular rate feedback loops. Moreover, the method includes
implementing the multivariable road wheel controller to control tracking
of the actual left and right wheel angles with the left and right road
wheel reference angles, respectively. The method further includes
decoupling the left and right road wheel angles with the multivariable
road wheel controller in the road wheel servo control system. The
multivariable road wheel controller controls the left and road wheel angle
based only on the left road wheel reference angle independent of the right
road wheel reference angle. Also, the multivariable road wheel controller
controls the right road wheel angle based only on the right road wheel
reference angle independent of the left road wheel reference angle.
