A steering system with reduced coupling between a position overlay unit
and a torque overlay unit may include a remote valve assembly for
controlling a hydraulic assist force or an electric motor for providing
torque overlay and electric assist to a rack of a rack and pinion
steering system. In one embodiment, the position overlay unit may provide
the assist force and the torque overlay unit may provide a motor command
signal to the motor of a differential positioned on a steering shaft. In
another embodiment, the position overlay unit may provide the motor
command signal and the torque overlay unit may provide the assist force.
In either embodiment, the position overlay unit may include variable
ratio gain that uses a position signal to output a variable ratio
command.