System and method of controlling vehicle steer-by-wire systems

摘要

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. The method includes modeling the multivariable road wheel controlled plant and implementing the multivariable road wheel controller. Moreover, the method includes applying road wheel angles and angular rates as feedback signals to construct a servo control system with the multivariable controlled plant and the multivariable road wheel controller to implement the left and right road wheel angles tracking for left and right road wheel reference angles. Then, the method includes receiving left and right road wheel reference angles being based on the steering wheel angle command from the steering wheel control sub-system and receiving the left and right road wheel angles from the multivariable road wheel controlled plant. The method includes calculating the left and right road wheel angle errors based on the left and right road wheel angles and left and right road wheel reference angles and generating the left and right road wheel torque control variables from the multivariable road wheel controller with servo control performances based on the left and right road wheel angle errors. After generating road wheel torque control variables, the method includes applying torque control variables of the multivariable road wheel controller to the multivariable controlled plant to control tracking of the actual left and right wheel angles with the left and right road wheel reference angles, respectively.