A stereo vision based method for autonomous spray of pesticides to plant leaves

In this paper, a 3D leaf position measurement method based on stereo vision is proposed for guidance of an autonomous spray robot. A binocular stereo vision system is constructed by a single camera, which can move up and down on the vertical arm of the robot. With this vision system, a disparity map that contains the depth information of the plant leaves are calculated from the acquired image pairs firstly. Disparity map is a mid-step of 3D reconstruction and describes the relative changing depth and contour of the object surface. After processing the disparity map, leaves are segmented and their depth regarding local camera coordinates could be measured. However, camera coordinates does not provide complete 3D information for autonomous spray. The measured results from the local camera coordinates were further converted to the robot coordinates that are uniform for the robot control. The experimental data carried out with simple-shaped leaves were evaluated with the results from the proposed method.