Automatic Control System Of Orchard Tractor Based On Laser Navigation

Because of the complex environmental characteristics, it is difficult to carry out mechanical automatic operations in orchard. The goal of this study is to develop the navigation system based on a laser scanner capable of navigating sprayer automatic operating in the orchard. A converted Fukuda-Oubao tractor was used as the platform. This system can navigated the tractor move automatically in straight line and curve line respectively in the simulative orchard condition. In the straight line test, a proportional controller was designed with the direction deviation and lateral deviation as input; in the curve line test, a controller based on fuzzy control was designed. The results of this study were summarized as follows:(1) Laser ranging technology was applied in fruit trees position; and a new method for fruit trees position information extraction was proposed, the method made fruit trees positioning more accurate.(2) The vehicle dynamic coordinate system was established, and the fruit trees position information scanned by the laser scanner was converted from polar form to rectangular form, the fuzzy location information in the orchard was fixed. The accurate fruit trees position information provide obstacles and path identification, navigation path planning with data support.(3) According to analysis on the actual driving experience Vehicle kinematics model based on preview control was designed in this study.(4) According to the analysis of actual road in the road, navigation path planning algorithm based on the least square algorithm was developed when the tractor move in straight line, a proportional controller based on PID theory was designed to navigate the tractor move automatically in straight line.(5) Navigation path planning algorithm based on quadratic curve was developed when the tractor move in curve line, a fuzzy controller based on fuzzy logic theory was designed to navigate the tractor move automatically in curve line, and the deviation from the front and rear wheel shafts center to the rail path was taken as input.(6) The whole design of the system was completed in"VC++"development platform. The maximum error was 15cm within 50m driving stance at the speed of 0.27m/s in the straight line test; the maximum error was 17cm in the quarter turn test; the maximum error was 35cm in the sine curve test.