Automatic Driving Control Technology For Tidal Flat Shellfish Harvester

Harvesting is an important part of tidal flat shellfish cultivation.It is an urgent problem to reduce the leakage of shellfish and improve the level of intelligent technology.In this paper,according to the technical requirements of tidal flat shellfish vibration harvester developed by our research group,the automatic steering control technology of tidal flat shellfish vibration harvester is studied,which provides technical support for the automatic driving control of tidal flat shellfish vibration harvester.The real-time position and attitude positioning system of the harvester is determined.The number of visible satellites and the PDOP values were analyzed by using GPS Global Positioning System based on the working conditions of tidal flat and the acquisition characteristics of vibration harvester.The results show that when the cut-off height angle is 10°,the average number of visible satellites is 6.47,the PDOP parameter value is 2-3,and the optimal cut-off height angle is 10° in the operation condition of tidal flat.A fuzzy control algorithm with correction factor was designed to correct the movement trajectory of the harvester,and its control effect was verified by Matlab.The kinematics model and the trajectory error model of the harvester were established,and the rotating speed and heading angle of the crawler driving wheel of the harvester were calibrated,the maximum skid rate of the crawler is 3.3% and 2.6% when the speed of the harvester is 0.12m/s in dry tidal flat and 0.15m/s in wet tidal flat.The results of Matlab simulation show that the control precision of fuzzy control algorithm with correction factor is improved by 66.7% and 33.3% respectively compared with the conventional fuzzy control algorithm when the speed of acquisition machine is 0.12m/s and 0.15m/s,respectively,the control time was shortened by 44.4% and 35.7%respectively.The development of automatic driving control system is completed.A combined control system with PC as Upper Computer and vehicle controller as Lower Computer is designed,and the selection of vehicle controller,Electronic Control push rod and GPS satellite positioning module is completed,the man-machine interaction program for automatic driving of harvester is developed by using Lab VIEW.The experiment of automatic running control system for tidal flat shellfish harvester was carried out.The results of capture test in tidal flat shellfish cultivation area showed that the positioning error of GPS satellite positioning module was less than 8cm when the speed of trap was 0.15m/s,and the speed of trap was 0.12m/s and 0.15m/s respectively,the average lateral deviation is 0.057 m and 0.067 m,and the maximum lateral deviation is 0.14 m and 0.2m,respectively.The results show that the automatic driving control system meets the requirements of tidal flat shellfish harvesting machine.