Sucker detection of grapevines for targeted spray using optical sensors.

摘要

Chemical control of suckers has been proven to be a validalternative and could gradually replace other methods of sucker removal in vineyards. But the potential for environmental pollution and cost increase due to overapplication negatively affects its acceptance by grape growers. Targeted application in proportion to the amount of suckers on a vine-specific basis can reduce chemical applications and alleviate potential problems. A sucker detection system consisting of a laser scanner for vine detection and a color camera for imaging suckers was developed to trigger targeted spray for vine-specific sucker control in grape vineyards. The camera was installed directly below the laser scanner. The laser scanned vine trunks two-dimensionally to calculate the diameter and position of the vine trunk, which then triggered the camera to capture a sucker image as soon as it faced the trunk directly. Extra-green image segmentation was used to identify the green targets from the background. A sucker window was located in the image after segmentation. With the distance information supplied by the laser scanner, the actual dimensions of the sucker window were obtained. The results of field tests showed that the developed system could identify more than 97% of the suckers at three travel speeds from 1.6 to 3.2 km h-1. The average accuracy of sucker dimension measurement ranged from 83% to 88%. The root mean square error (RMSE) of the relative position of suckers to the corresponding trunk varied from 13 to 29 mm. The real-time laser positioning and image processing made this system practical and suitable for targeted spray for sucker control.