A Study on Integrated Control of Tractor Speed and Tillage Depth for Power-Shift Tractors Based on Workload Adjustment

Complex unstructured factors, such as the spatial heterogeneity of soil mechanical properties and random variations in farmland topography, cause fluctuations in working load, resulting in low efficiency and poor quality of subsoiling operations. To address this, this study developed a combined speed–tillage depth control system for power-shift tractors based on working load adjustment. Based on dynamics theory, a six-degree-of-freedom dynamic model of the tractor subsoiling unit was established. Through simulation experiments, the working quality of the combined speed–tillage depth control system was evaluated under different working speeds, tractor gear positions, and traction resistance conditions. Simulation results indicated that under stable working conditions, the speed control error was <0.03 km/h; when the increase in traction resistance was less than 4000 N, the speed control error was less than 0.19 km/h; and when the increase in traction resistance exceeded 4000 N, the speed control error was <0.53 km/h. Field test results indicated that the speed control error was less than 0.6 km/h, the tillage depth control error was less than 4 cm, and the slip was less than 0.25. The coordinated speed–tillage depth control system developed in this study enables precise control of speed and tilling depth under dynamic operating conditions.