Determination of wheel acceleration / deceleration for use in integrated stability control systems

One of the key technologies of automotive active safety systems is to measure the wheel speed and calculate wheel angular acceleration or deceleration as accurate as possible. The accuracy of these crucial inputs parameters is extremely critical for active safety systems irrespective of the control logics used to realize the control function. Determination of acceleration / deceleration of rotating / moving body is not simple, especially when the range of measurement is large, measurement accuracy constraints are stringent, measurement intervals are small, computation resources are restricted like in case of an electronic control unit , resolution of hardware timer is not infinitesimally small and input signals are noisy. This paper is a result of an extensive study carried out on various methods suggested in several patents filed on this topic and subsequent modifications to these methods to improvise the performance in terms of range of measurement (+/-0.01 g to +/-50 g), accuracy of measurement (1%), time response 5 msec& improved noise immunity. This paper proposes two novel methods for determining the wheel acceleration/deceleration for usage in active safety systems such as ABS and ESP: one based on dynamic circular buffer and the other based on time accumulation technique. This paper also provides the results of comparing the performance of conventional method with the methods proposed in this paper.