Integration of an Adaptive Control Strategy on an Automated Steering Controller

Abstract

This paper describes an adaptive control strategy for improving the steering response of an automated vehicle steering controller. In order to achieve repeatable dynamic test results, precise steering inputs are necessary. This strategy provides the controller tuning parameters optimized for a particular vehicle's steering system. Having the capability to adaptively tune the steering controller for any vehicle installation provides an easy method for obtaining precise steering inputs for a wide range of vehicles, from small off-road utility vehicles to passenger vehicles to heavy trucks. The S.E.A. Ltd. Automated Steering Controller (ASC) is used exclusively in conducting this research. By recording the torque input to the steering system by the steering controller and the resulting steering angle during only a single test, the ASC is able to characterize the steering system of the test vehicle and create a computer model with appropriate parameters. With this information about the vehicle, the computer model and adaptive controller automatically tune the ASC control gains for that vehicle. The S.E.A. Ltd. steering controller is described briefly. See reference [5] for a detailed description of the ASC development. The steering system model development is described, and the model itself is validated using in-vehicle test data. Various system identification and controller tuning methods are discussed. The adaptive control strategy performance and robustness to steering parameter uncertainty is investigated. Finally, examples of the adaptive control strategy using results from full-scale vehicle tests are presented.