|Sudduth, Kenneth - Ken|
Submitted to: American Society of Agricultural Engineers Meetings Papers
Publication Type: Other
Publication Acceptance Date: 4/11/1997
Publication Date: N/A
Interpretive Summary: Many producers are beginning to use combine yield monitoring systems to map grain yield variations in their fields. These yield monitoring systems measure grain flow rate and combine travel speed to calculate a yield for each point in the field. The width of cut (or swath width), which is also needed for the yield calculation, is manually entered by the combine operator. With the manual approach, significant swath width errors, which then translate into yield errors, can occur when harvesting drilled crops and/or irregularly shaped fields. To eliminate these errors, an electronic swath width measurement system was developed. The system was based on an ultrasonic distance sensor, similar to those used for automatic focusing cameras. The measurement system was tested in the laboratory and field and was found to have an accuracy of 4 inches or better during normal harvesting operations. This research will impact producers and agribusinesses interested in using yield mapping as part of their management system. Use of the electronic swath width measurement system will allow them to produce more accurate yield maps with less work on the part of the combine operator. The more accurate maps will then translate into more accurate precision agriculture management plans for the mapped fields.
Technical Abstract: A combine swath width measurement system was developed based on a commercial ultrasonic distance sensor. Temperature compensation was implemented to minimize measurement error. The distance readings of the ultrasonic sensor during dynamic tests in wheat were highly variable. However, a major portion of the readings were close to the actual distances, and filtering techniques were able to extract useful informatio from them. A running median method worked better than running mean or running mode for data filtering. Sampling frequency influenced the accuracy of the distance measurement and should be set as high as possible for improved accuracy. The travel speed of the combine influenced swath width measurement to some extent, and operating at a lower speed could yield more accurate data. On a mean absolute error basis, the overall accuracy of ultrasonic swath width measurement in the field was less than 10 cm when the gap between the ultrasonic transducer and wheat edge was within 1 m and was less than 15 cm when the gap was in the range of 1 m to 2.5 m.