1. Field of the Invention
The present invention relates generally to systems for grading or analyzing agricultural solids, such as cotton. More particularly, the present invention relates to an automated calibration system for sensors that are used for analyzing and grading agricultural solids.
2. Related Art
Cotton and other agricultural solids are officially classified and graded by the United States Department of Agriculture (USDA) Agricultural Marketing Service (AMS), as well as other organizations. This is accomplished by the measurement of numerous properties of the cotton such as color and trash content. A camera-type sensor is typically used to measure the color of the cotton, as well its trash content. Some organizations further utilize a separate moisture sensor, such as an infrared moisture sensor, to measure moisture content. These same sensors may also be used in a gin to monitor the properties of the cotton as it is being processed.
Industry protocol for measurement of cotton color and trash in a typical gin processing system requires verification of sensor calibration, and recalibration if necessary, after approximately every four hours of operation. Calibration has heretofore been done manually, using five different color reference tiles and one trash reference tile. In this process, five color reference tiles are sequentially placed in the viewing position for the color/trash camera sensor, with measurements from the color sensors then being taken and recorded for each individual tile. The gathered measurements are then used to calculate coefficients that optimally correlate the measured values with known color reference values. Similarly, a singular trash reference tile, with a known percentage of surface area occupied by dark spots, is manually placed in the viewing position for the color/trash camera sensor. Upon its measurement by the trash sensor an iterative process is used to calculate coefficients that optimally correlate the measured values with known trash content reference values.
Because cotton cannot be graded or analyzed during the sensor calibration process, the calibration process results in downtime for its processing. Presently calibration is a manual operation which is inefficient due to its being time and labor intensive. Therefore, there is a need in the art for a calibration system that can quickly and repeatably calibrate sensors without requiring continuous operator intervention.