High Efficient Cooperation Control of Distributed Motor Drive Electric Tractor Considering Complex Farmland Operation Conditions

Electric tractors have been increasingly favored in modern smart agriculture due to their flexible maneuverability, quick dynamic response, and zero emissions. However, during complex farmland operations involving frequent traction and turning, traditional tractors, constrained by insufficient four-wheel cooperation, are prone to dynamic wheel slip, inter-wheel drag, and chassis oscillations, which generate additional soil compaction besides that caused by unavoidable vertical loading and could ultimately lead to excessive soil compaction. To effectively tackle these challenges, this paper proposes a distributed motor drive electric tractor (DMD-e-Tractor) equipped with four in-wheel permanent magnet motors. Furthermore, a double-layer cooperation control strategy is proposed to enhance the cooperation among distributed drive motors and alleviate excessive dynamic soil compaction during field operations. Specifically, in the lower-level control, a fixed-time extended state observer (FTESO) is designed to ensure high consistency in dynamic response among motor systems, as well as high cooperation in compensation control. In the upper-level control, an improved mean deviation coupling structure is proposed, and a nonsingular terminal sliding mode control is designed by utilizing FTESO. Finally, the experimental are conducted and the results show that the proposed strategy can effectively improve the cooperation control performance of the DMD-e-Tractor distributed motor drive system and alleviate excessive soil compaction.