In 1996, cotton yield monitors were not commercially-available. To facilitate in-field yield variability research, a weighingbasket was installed in a Case IH 2155 cotton picker. Data gathered with the weighing basket allowed generation of cottonyield maps containing one data point per second of machine operation. Following basket installation, a set of tests wasplanned to evaluate measurement system performance. Tests were designed to allow evaluation of the uncertainty expectedin each individual yield measurement. System dynamic response was also evaluated. One important objective was to generatedata representative of typical operating conditions, thus tests were conducted while the harvester traveled along the edgeof a cotton field. Known flow rates were provided by pumping water into the weighing basket, and a turbine flow meter wasused as a comparative reference. Step loads were applied to allow investigation of system response time requirements. Resultreporting techniques were derived from the American National Standard for test uncertainty and common system analysistexts. According to test results, the uncertainty associated with any individual steady-state flow rate measurement couldbe expected to fall in the range of ± 0.4 lb/s (95% confidence). This corresponded with ± 480 lb seed cotton per acre (95%confidence) assuming a four-row picker configured for 40-in. rows traveling at 2 mph. Random uncertainty was dominant(±0.4 lb/s, max) when compared with systematic uncertainty (±0.04 lb/s, max), thus spatial averaging has potential to reduceuncertainty in yield measurements. Dynamic responsiveness was limited by filtering techniques used to reduce the effect oftransients in basket weight versus time data. Rise time was used as the measure of dynamic responsiveness, and had a maximumvalue of 11 seconds when responding to a step load. The assumed 4-row harvester covers 0.01 acres in 11 seconds.Testing and result reporting methods used in this study can be modified for future use in performance testing of mobile, continuous-weighing flow rate measurement systems.
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