Predicting and Achieving Objective Steering Performance Measures

Previous work has shown power steering boost gains are uniquely determined given a vehicle and a single objective target. The objective target used was steering gain, S_g, vs. lateral acceleration, a_y, where steering gain is defined as the slope of the torque vs. lateral acceleration relationship. The previous work is expanded and applied to real world steering systems. Specifically, methods are provided to determine boost gain shapes given a user-defined steering gain vs. lateral acceleration specification or steering gain vs. torque specification. Each specification method is described in detailed steps. Approximations of each method are discussed and analyzed for practical use. The influence of static friction on steering performance is derived. It is shown that the hysteresis of the steering system is due to a coupling between static friction and a vehicle parameter that is easily derived from the bicycle model. Test results are provided to validate predictions.