Path Following Control Of Tractor With An Electro-Hydraulic Coupling Steering System: Layered Multi-Loop Robust Control Architecture

Tractor path following control usually suffers from the uncertainties and disturbances especially when tractors are faced with uneven soil. As the main actuator of path tracking control, a electro-hydraulic coupling system has parameter uncertainties and disturbances. Conventional methods pay little attention to the electro-hydraulic coupling system which can generate poor path tracking performance. A layered multi-loop robust control architecture (LMLRC) is proposed including a path tracking layer, an angle tracking layer, and a current tracking layer. The path tracking layer is obtained by model predictive controller (MPC) considering uncertainties and disturbances. The angle tracking layer has a sliding mode controller (SMC) which takes parameter uncertainties and disturbances of electro-hydraulic coupling system into consideration. It is designed to follow the target angle generated by path tracking layer and outputs a tracking torque. The current tracking layer is designed by Proportion-Integration-Differentiation (PID) controller to track the torque output by angle tracking layer. To verify the proposed controller, simulation test and hardware in the loop (HIL) test were implemented. The results show that when faced with uncertainties and disturbances the LMLRC is more effective at path following. Moreover, better dynamic stability is exhibited when compared with other controllers. (c) 2021 IAgrE. Published by Elsevier Ltd. All rights reserved.