Research On The Drive Control Strategy Of Wolfberry Harvesting Platform Based On Electric Drive

Chinese wolfberry is an economic forest fruit which has advantageous geographic characteristics of Ningxia.Currently,manual picking is maily adopted in wolfberry harvesting,while this kind of intensive picking because of its seasonal maturity increased harvest cost greatly.To better develop the wolfberry industry and realize the mechanized harvesting of wolfberry,a wolfberry harvesting platform based on electric drive is constructed in this study,and the object is to explore drive control strategy of the platform.Firstly,the platform model selection is determined taking wolfberry planting environment into account.Secondly,the motor drive-control system is investigated according to the operational requirements of the harvesting platform,therefore,a fuzzy PID-based vector control strategy of the permanent magnet synchronous motor is proposed.Finally,the torque distribution strategy is developed with the drive antislip control as the constraint and the improvement of the comprehensive efficiency of the harvesting platform as the goal,and the drive control strategy is modeled and jointly simulated,so as to verify the feasibility of the drive control strategy designed in this paper.The main work of this paper is as follows:(1)Power system design and selection.According to the performance requirements and operating conditions of the wolfberry harvesting platform,establish the front and rear axis dual motor drive power system configuration,analyze the platform under different working conditions of the force,combined with the project requirements,the platform key components selection and preliminary parameter matching.(2)Motor control strategy research.Through simulation experiments comparing traditional PID control method and fuzzy PID control method,the results show that the time and overshoot of reaching the reference speed with fuzzy PID control are 0.013 s and 1.7 r/min respectively;when the torque changes,the change of fuzzy PID speed is 2 r/min,and both are better than traditional PID control.It shows that the vector transform control system under fuzzy control can output more stable speed and torque,and has better anti-interference ability to meet the driving demand of the harvesting platform and improve the stability of the harvesting platform in the field operation.(3)Optimal torque distribution strategy of the drive system.Based on the requirements of the working conditions of the harvesting platform,the torque distribution strategy is designed from the principles of power,economy and stability,which is suitable for this paper.Firstly,the optimal torque distribution method of different components is analyzed,and the comprehensive efficiency optimization method based on motor power loss is determined,and the torque distribution strategy model of the harvesting platform is established by using Matlab.Secondly,in order to improve the vehicle stability,a dual-motor drive anti-skid control strategy based on PID controller is built,and dynamic torque limitation is performed for the efficiency-optimal torque distribution strategy.Finally,the torque distribution strategy with the drive anti-skid strategy as the constraint and improving the comprehensive efficiency of the harvesting platform as the goal is proposed to provide the theoretical basis for the subsequent joint simulation of the harvesting platform control strategy.(4)Drive control strategy validation.The Wolfberry Picking Driving Cycle(WPDC)was established according to the operating conditions of the Wolfberry harvesting platform,and a joint simulation model of the harvesting platform drive control strategy was established in Cruise and Matlab/Simuink software for analysis of the conditions.The results show that,in terms of dynamics,under the China Light Vehicle Test Cycle(CLTC)and WPDC conditions,the vehicle speed follows well and can respond to the speed change of the cycle conditions in time,and the model dynamics meets the requirements of platform dynamics;in terms of economy,the introduction of the torque distribution strategy and the torque distribution strategy designed in this paper In terms of economy,the introduction of the torque averaging strategy and the torque distribution strategy designed in this paper can reduce the 100 km electric power consumption by 4.06%and increase the range by 5.26%;in terms of stability,the slip rate of the front and rear axles under WPDC conditions is about 20%,which meets the design target of the platform drive antiskid control strategy developed in this paper;at the same time,it also verifies the effectiveness of the drive control strategy proposed in this paper.This paper researches the torque distribution method and motor drive control strategy suitable for agricultural electric drive harvesting machinery,and obtains that the motor drive control strategy based on fuzzy PID and the torque distribution strategy with the drive anti-slip strategy as the constraint and the goal of improving the comprehensive efficiency of the harvesting platform can meet the drive requirements of the platform for efficient operation,which provides ideas for the research of the control strategy of electric drive agricultural harvesting machinery.