Cruise control with adaptation and wheel torque constraints for improved fuel economy

Cruise controllers are used to automatically control the speed of motor vehicles. In order to maintain a desired vehicle speed the controller takes over the throttle in a cruise control system which proves particularly useful for long drives. Adaptive Cruise Control (ACC) systems have additional capabilities such as automatic braking or dynamic set-speed type controls and hence can accommodate changes in cruise speed required to adapt to changing road conditions. We propose that further improvement in fuel economy can be achieved by considering the vehicle´s longitudinal dynamics as an input-constrained system and the wheel torque as the corresponding constrained input. We effectively address the resulting input saturation nonlinearity by employing our adaptive anti-windup compensator design. Simulation results are used to compare the performance of the original cruise control system allowing for the full-range of wheel torque and the ACC system where the wheel torque is forced to remain within the user-defined limits for improved fuel economy.