Design of robust vehicle launch control system

This paper presents a robust algorithm for vehicle start-up from a stop (commonly referred to as "vehicle launch") using a microprocessor controlled friction clutch. The design applies an "M-exclusion" concept for achieving guaranteed robust tracking and stability using quantitative feedback theory (QFT). The analytical design technique is carried out in the complex plane and improves on the conventional graphical QFT design. An inner control loop achieves a second-order response within specified tolerances for the driveline and clutch. An outer loop develops a reference signal for the inner loop to achieve smooth lockup. A feedforward signal derived from engine acceleration prevents both over-speed and speed droop in the engine. The control algorithm was programmed into a microprocessor and tested in a heavy duty truck. The truck was driven by experienced drivers, who rated the smoothness and responsiveness of the launch better than achievable with a manual clutch.