The Impact of Control Structure on the Path-Following Control of Unmanned Compaction Rollers 2020-01-5030

The unmanned roller (UR) can improve the compaction quality and efficiency simultaneously, but suffers from the challenges in path-following control. This is a direct result of 1) the increased degree of freedom in motion from the articulated structure of UR, and 2) the uncertainties from the road condition and position measurement. In this paper, the impact of control structure on the path-following control performance of UR is investigated through a comparative study. The parallel controller, for the lateral error and orientation angle error respectively, as commonly used in passenger vehicles, is used as the baseline. A cascaded disturbance rejection controller is proposed for comparison, where the high-level controller seeks to minimize the lateral error by adjusting the desired orientation angle, to be achieved by the low-level controller through the manipulation of the steering wheel. The superiority of cascade controller over the parallel controller was evaluated in experiments. Results show that the proposed cascade controller is more robust to GPS (Global Positioning System) antenna installation error. When operating on road with large rocks, the cascade controller also shows improved disturbance rejection capability in terms of 87.5% reduction in recovery time. These benefits are achieved due to the local orientation angle feedback controller, relative to the parallel controller. One adverse effect of cascade control is the 26.8% higher electrical energy consumption of the steering system.