Optimization of Drivability Control Functions with Two-Stage Rate Limiters

Abstract

Load changes in automotive drivelines may cause uncomfortable vibrations. A suitable motor torque control is able to remedy this problem. Often, a two degrees of freedom structure is used in these drivability control functions. In this structure, the desired motor torque is pre-filtered by a multi-stage rate limiter. However, those functions are still parametrized experimentally by laborious test drives or on the test-bench. This paper addresses the model-based optimal parametrization of these rate limiters in automotive drivability functions. For this, a recently published gear specific model is identified and validated for another gear position. In addition, a linear transfer function of multi-stage rate limiters is approximated by the transient input describing function method. The characteristics of this transfer function are used to reduce the number of design variables for the multi-objective optimization of a two-stage rate limiter for drivability control.