Song, P., Xie, S., Zhong, Y., and Gao, B., "A Unified Creep-Speed Control Approach for Automated Parking System," SAE Technical Paper 2017-01-0609, 2017, doi:10.4271/2017-01-0609.
This paper presents a unified creep-speed controller specifically designed for the automated parking system of an automated manual transmission vehicle, whereby the engine management system, transmission control unit, and electronic stability control system can work cooperatively and harmoniously within the same control framework. First, a novel reference speed generator is designed and employs sinusoidal functions to produce the speed profile based on the maneuver-dependent distances computed by a path planner, such that the lag in vehicle response during start-up can be effectively reduced. Second, a well-tuned PID controller is adopted to determine the resultant longitudinal force in attempt to follow the reference speed and eliminate the distance error during the parking maneuvers. Third, the electronic control units in the powertrain and brake systems interact with one another and generate exclusive control actions in order to achieve the desired motion control command, where the non-smooth actuator nonlinearities are explicitly addressed. Finally, the proposed controller is validated through simulation to improve the tracking accuracy of the predefined time-dependent parallel-parking trajectory at creep speeds.