Development and validation of an automated steering control system for bus revenue service

This paper presents the development and validation of an automatic steering controller that has been successfully implemented on a 18.3-m articulated bus for revenue service in Eugene, Oregon, USA. The automated steering system provides both lane keeping and S-curve precision docking on a 4-km-long narrow and curving urban segment with six stations and mixed traffic lanes while the operator controls the speed. The objective of deployment with an extended period of revenue service (carrying passengers) elevated the system safety and performance requirements. To meet the requirements, the controller needed to address accuracy, robustness, comfort, and fault tolerant capabilities. The baseline high-gain controller adopted for the automated bus takes the structure of the steering mechanism of a human driver with optimized parameters. The fault tolerant control incorporates a family of Kalman filters to sustain the automation after part of the sensing system fails. The resultant system achieved all performance requirements and the revenue service started in June, 2013.