Analog fuzzy implementation of a vehicle traction sliding-mode control

Abstract

Road adherence is an imprecise function of many parameters stronglyaffected by road conditions. In this paper, we propose a very robust control with astatic nonlinear feedback law which can consider adherence and other modeluncertainties, regulating the wheel slip at any desired value with good precisionproperties. A sliding-mode control has been designed to provide stability andreliability. Once designed, the control surface has been fuzzified and implementedwith a programmable analog fuzzy circuit which uses a 0.7 mu m CMOStechnology provided by SGS-Thomson Microelectronics. This implementation iscarried out with a semi-automatic design flow and features high computationalefficiency at it very low cost, especially when compared to a digital one.Moreover, the controller response time is less than 1 mu s. A flexible control of theslip coefficient has been performed. Results show that the desired slip coefficientis reached and kept with good approximation in compliance with theoretical results.