CONTROLLING AN ASSIST MOTOR USING A BLENDING FILTER

A method for controlling an electric assist motor (50) for providing steering assist in response to a sensed torque signal (taus) includes the step of filtering the sensed torque signal to provide a low frequency torque signal (tausL) and a high frequency torque signal (tausH). A low frequency assist torque signal (tauassistLF) is determined as a function of the low frequency torque signal (tausL). A high frequency assist gain signal (Kmax) is determined as a function of the sensed torque signal (taus) and a sensed vehicle speed (nu). The high frequency assist gain signal (Kmax) is applied to the high frequency torque signal (tausH) to determine a high frequency assist torque signal (tauassistHF) A torque command signal (taucmd) is determined as a function of the low frequency assist torque signal (tauassistLF) and the high frequency assist torque signal (tauassistHF) The electric assist motor (50) is commanded to provide steering assist in accordance with the torque command signal (taucmd).