| In recent years, the robot technology and visual navigation have developed rapidly, and its expansion in the agricultural field receives widespread concern. The research and application on the agricultural utility robot technology not only can solve the operational difficulties in the agricultural environment and reduce the labor intensity, but also suit the market demand, increase economic efficiency and has realistic meaning to accelerate the agricultural modernization. This paper is supported by the"863"project (2008AA100903-7) and its studying object is the new developed crawler orchard farming micro-machine. The paper researched and designed an orchard robot control system based on visual navigation. The main research work as followed:(1) Overall design and analysis of orchard robot control system. Firstly, proposing the orchard robot platform architecture and design the overall frame of control system hierarchically and modularly. Then, dividing the robot control system into vision subsystem and motion control subsystem, and designing the hardware and selecting components.(2) The design of vision subsystem. The vision subsystem has one single camera. The improved two-step calibration method based on OpenCV was chosen after experimental results compare of two methods. Based on analyzing in depth the position relationship between the orchard machine moving route and navigational path, the conversional equations of image information in the farming environment and planed mission parameters was derived. According the image features of the two standardized orchard road environment the article chosen, the images processing algorithm and the navigating center line extracted algorithm were analyzed and designed in detail with using the high-performance processing core of TMS320DM642.The extracting methods of navigation path based on two points and pre-limited bilateral Hough transform were proposed, and analyzed by stability and real-time.(3) The design of motion control subsystem. The motion control system uses the fuzzy control method to convert the lateral deciation and heading angle obtained by vision subsystem to the corresponded control signal of hydraulic system. The fuzzy controller and modeling of fuzzy control system were researched and designed detailed by using the software of MATLAB. Finally, fuzzy control system was simulated in the simulation environment of SIMULINK. The result shows that the fuzzy controller run with strong robust, response with high accuracy, has good control effect and meets the basic design request.(4) Software implementation of the orchard robot control system. The whole control system of the orchard robot was divided into the vision subsystem software which the control core was DM642 and the motion control system which the control core was AT89S52.Then, all the parts that were divided according to the functions of each subsystem were analyzed and designed detailed, and a part of procedures was given. |
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