DESIGN OF A MODEL-REFERENCE ADAPTIVE CONTROLLER FOR VEHICLE ROAD FOLLOWING

The design of a model reference adaptive controller (MRAC) for vehicle road following is discussed. There are many factors which make automa tic lateral control of vehicles difficult. These include changing vehi cle parameters, changing road conditions,:as well as disturbances caus ed by wind and other factors. Traditional controllers have difficulty guaranteeing performance and stability over a wide range of parameter changes. Model. reference adaptive controllers on the other hand, can guarantee both stability and performance over a wide range of slowly v arying parameter changes as long as several conditions are met. Diffic ulties with model reference adaptive controllers (as well as other con trollers) arise when saturation appears on the input or states. For ve hicle applications, the steering angle is limited. Therefore, the adap tation gains for the MRAC designed in this paper were chosen so that t he steering command remained reasonable, even during adaptation. We fi nally show that there is a tradeoff regarding input amplitude and inpu t frequency during adaptation.