Joint control method based on speed and slip rate switching in plowing operation of wheeled electric tractor equipped with sliding battery pack

Abstract

For the wheeled electric tractor with a sliding battery pack, a switching control system between the tillage speed and slip rate was developed for the plowing operation to meet the agronomic requirements of efficient and high-quality operations. The plowing dynamic model of the tractor was firstly established. Then, a switching control method was proposed on the basis of adjusting motor torque and battery pack displacement. Using the slip rate as a switching condition, the sliding-mode control algorithm was utilized to raise the speed to 6 km/h when the slip rate was less than 20%. Otherwise, a designed SSA-RBF-PID controller was used to keep the slip rate below 20%. Finally, a real vehicle testbed was built and plowing tests were conducted. The research results showed that the proposed method can effectively control the speed and slip rate under varying plowing resistance without adjusting the tillage depth. The average slip rate is reduced by 38.26% while the speed is kept around 6 km/h, and the traction efficiency is improved by 22.84%. In addition, the tillage depth error is decreased compared with the slip rate control based on the tillage depth adjustment, which is significant to improve tillage efficiency and keep tillage depth uniformity.