Date of this Version
The use of satellite-based positioning has advanced considerably in the world of agriculture, providing a range of technical solutions that include the automated steering of tractors and self-propelled machinery. With the development of auto-guidance systems comes the need to evaluate their performance. Given that current precision and accuracy claims are relatively small in magnitude, it is imperative there be a testing system capable of detecting errors with ten times greater accuracy-- possibly as little as a few millimeters. A visual sensor was adopted to achieve this level of measurement resolution. The sensor was used to determine the cross-track error estimates necessary to summarize pass-to-pass and long-term levels of accuracy. To test a tractor with auto-guidance capability, the system was mounted to the tractor's chassis to log the tractor's relative position as it passed through the same course multiple times. Several different pilot tests have been conducted operating tractors at three travel speeds (1.0, 2.5 and 5.0 m/s). The values or guidance error estimates corresponding to 95% of the cumulative unsigned error distributions can serve as publicly acceptable test summaries. The results of this study can be used to pursue standardization of the auto-guidance test process.