Electric tractors driven by dual motors have become a critical research topic in the field of pure electric tractor research. As a key component of the transmission system, the optimization of the internal parameters of the power-coupled transmission gearbox has a crucial impact on the power transmission of the whole machine. This work combines the characteristics of low speed and high torque during tractor operation, and adopts the transmission form of double motor input and double planetary group coupling output to design the transmission structure of the gearbox. Then, this paper proposes a dynamic optimization method of the transmission system based on the Improved Deep Deterministic Policy Gradient (IDDPG) algorithm, which realizes the optimization of the gear ratio of the transmission system by constructing a virtual prototype and hardware-in-the-loop simulation environment. In transport mode, the optimized gear ratios shorten the acceleration time of the tractor from 0-20 km/h by 13.6% and increase the motor efficiency by 10%; in rotary mode, the acceleration performance is improved by 28.5% and the motor efficiency is increased by 5%. The study shows that the proposed method is significantly better than the traditional static design and provides a new technical path for the intelligent optimization of the electric tractor drive train, while promoting the efficient and sustainable development of agricultural machinery.

The high-gap plant protection machine is taken in this paper as the research object to ensure the good driving power and safety of the high-gap plant protection machine, and the control strategy of inter-shaft torque distribution is established under different working conditions to improve vehicle power and lateral stability. The anticipated demand torque is initially determined based on the structural characteristics and operational principles of the plant protection machine. Subsequently, a hierarchical control framework is devised by incorporating a formulated switching control strategy. Finally, a simulation model for torque distribution control strategy between shafts is developed on the Matlab/Simulink platform, followed by simulation and experimental verification. The results are presented as follows: the inter-shaft torque distribution strategy established in this paper increases the average longitudinal acceleration by 0.13 m/s² and 0.14 m/s² under the control of low and high to low adhesion road surfaces, respectively. Under the control of the single-line shifting condition, the yaw velocity can successfully follow the expected value with a maximum value of 0.61 rad/s. The side deflection angle of the center of mass does not exceed 2.8°, which can follow the ideal trajectory and improve power and safety.