Design of a High-Performance Automatic Steering Controller for Bus Revenue Service Based on How Drivers Steer

This paper focuses on the design of an automatic steering controller that has been implemented on an 18.3-m articulated bus for revenue service. Compared with the typical environment for autonomous cars, the narrow and curving bus lane and the tight S-shape docking curves require a steering controller to consistently provide high accuracy with ride comfort. While analyzing the data of drivers steering through a double lane change course, we discovered and validated that driver's steering rate is proportional to a specific vehicle angle error. Subsequent analysis showed that drivers in effect execute a naturally robust controller that allows high-gain corrections and is insensitive to variations in vehicle dynamics and speeds. This paper presents the first adaptation of this driver's steering mechanism to a real-world challenging application. The resultant system achieved all performance requirements, and the revenue service at Eugene, OR, USA, started in June 2013. Moreover, the simple control structure greatly facilitated the design of fault detection, degraded control, and control redundancy.