Identifying Electrically Assisted Steering Transfer Functions using a Modified FIR Filtering Approach

The transfer function required to control an electrically assisted steering gear is identified using a modified FIR filtering approach. The topology of the electrically assisted steering gear is described. The modified FIR filtering approach is explained with emphasis on the frequency domain implication of window choice when performing measurements. An example is provided using an analytic model of the steering gear so that the accuracy of the technique can be evaluated on a known system. The technique is applied to measure the transfer function of an actual electrically powered steering gear on a test bench and in a rolling vehicle.