Research On Navigation And Localization System Of Field Working Machine Based On Two Laser Source

Precision location technology is an important research content in precision agriculture, which is also a key technology to realize the intelligent agricultural machinery. The areas in southern paddy field is so small that the expensive and high-precision DGPS could not been applied in more areas. In order to develop a low-price and high-precision location system applied in small-sized agricultural machinery in the south, a kind of the location technology based on the double laser-transmitter was proposed in this thesis. The distance from the laser-transmitter to the laser-receiver can be measured directly at first. Then the transmitting angle can be figured out in real-time. Therefore, the location coordinate of the moving machine and its moving state can be calculated, which provided technology supporting for navigation&location of the agricultural machinery and the fixed-point data acquisition in the field. The content of this thesis belongs to a part of "Research on navigation&location technology of robots working in the paddy field without any mark (09JJ6091)" in Hunan science fund as well as "Research on the key and simple&flexible machinery working in the paddy field "in national science&technology support project.Taking the high-speed rice transplanter2ZG630A as the test platform, the following main contents have been studied in detail such as the system's wireless switch way, laser spot recognition algorithm, the initialization way of the laser transmitting angle, the algorithm for tracking laser receiver and steering control algorithm, etc.1. After the characteristics of location and auto-driving of the machine working in the paddy field have been analyzed, combined characteristics the and cost of the present location system, the navigation and location method for the working machinery in paddy field based on the double laser transmitter was proposed.2. The system used2.4G wireless communication mode to realize the data exchange in real time. Because three-channel data communication (the two laser transmitters and the laser receiver target)may lead to the data communication collision, ring data exchange to realize wireless communication with the proper communication agreement was proposed to make sure the data transmission reliable.3. In order to get the accurate laser transmitter angle and the baseline length, the system used ultrasonic wave at point-to-point to measure the distance. Meanwhile, wireless communication mode helped to realize the start of the reference time. According to the projection principle, the problem about height drop between probes could be solved. By the temperature compensation and system error compensation, the initial distance measurement accurately among two laser emitters and laser receiver can be realized and the initialization of the rotation angle of the laser emitter and the length of baseline also can also be performed.4. In order to deal with the halo and diffuse reflection of the common laser transmitter, the algorithm about laser spot initialization combined the arithmetic average filtering and middle filtering algorithms were raised in this paper. After the theoretical deduction and test, the algorithm's availability and necessity had been proved.5. Because receiving target self-moving and vehicle vibrating lead to the deviation of laser spot center caused between checked and actual during the movement of object, the recursive α-β filtering algorithm with variable gain was taken for the laser spot center's second filtering after initial filtering to realize its dynamic pre-estimate. The accurate center of the laser spot also be gotten, which proved the algorithm's availability and necessity.6. In order to lock the moving laser receiver for a while and realize location calculation in real time, incremental PID quick erection Karlman filtering algorithm was raised after PID algorithm and Karlman filtering theory were studied deeply. It can realize that the double laser source can track and lock the moving receiver all the time and finish the system's high-precision location.7. Taking steering wheel controlling as a study target, the mathematic model of the steering control system was established, the way of the navigation control was studied deeply and fuzzy immune PID steering controlling algorithm was proposed. When Kp,Kt,Kd,K,η of the fuzzy immune PID take the6,2,2,0.5,0.5, the system can be controlled greatly. And the test also proved that the precision of the navigation and tracking could satisfy the requirement of agricultural machinery.