Bestandesorientierte automatische Nachführung landwirtschaftlicher Arbeitsmaschinen in Reihenkulturen mit Hilfe der digitalen Bildverarbeitung = Stand oriented automatic guidance for agricultural vehicles in row crops using digital image processing
Abstract
A stand oriented automatic guidance system for row crops was mounted on a Fendt Xylon 524 tractor. This system consisted of an image processing system, a vehicle specific controller and a proportional hydraulic valve. The development began with a Claas Autopilot with machine vision sensor and ended with the two-computer-system with vision-guided position controller, vehicle specific steering angle controller and a Load-Sensing compatible Danfoss PVG32 hydraulic valve. Image processing hardware was an ITI IC-PCI frame grabber with an AMC colour acquisition mo-dule in an AMD K6/II-300 host, a Pulnix TMC 50 RGB CCD-Camera was used as sensor. After transforming and rescaling the image of the camera's view, two guidelines were calculated from a binarised colour differential image, and, after validating their angle deviation, heading and offset errors were generated. The steering angle controller consisted of an AMD 486 DX 133 host with an AD/DA interface and the developped digital PID-controler. With the heading and offset error calculated by the image processing unit and the actual steering angle provided by the sensor, it supplied the hydraulic valve with the correction voltage, changing the front axle's steering angle. In several field tests performed, the system has shown to be stable, and, despite the increased working speed, not less accurate than the human operated variant.
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