PA—Precision Agriculture: An Analytical Grain Flow Model for a Combine Harvester, Part II: Analysis and Application of the Model

✍ Scribed by K. Maertens; J. De Baerdemaeker; H. Ramon; R. De Keyser

• Publisher: Elsevier Science
• Year: 2001
• Tongue: English
• Weight: 225 KB
• Volume: 79
• Category: Article
• ISSN: 0021-8634
• DOI: 10.1006/jaer.2000.0681

✦ Synopsis

A dynamic grain #ow model describes how the grain #ow at the end of the threshing process reacts to feedrate variations during harvest. These input #ow variations have di!erent origins as there are variations in travel speed, cutting width and locally variable grain yield. In this study, an analysis of the model is performed and a speci"c application in the domain of precision farming is illustrated.

A closer look at the construction of the analytical grain #ow model reveals some complicated dynamics in the system and an internal return loop with a signi"cant time delay. Especially, the latter property makes it di$cult to simplify the model into a linear transfer function, an interesting form for further applications. Due to a speci"c property of grain spreading in the return #ow, it is possible to compensate for the variations in the return #ow fraction. The grain smoothing e!ect of the combine harvester for 0% return #ow was approximated by a fourth-order linear transfer function.

Some producers of combine harvesters already possess a commercial product for online grain yield measurement. These sensors are typically mounted at the end of the threshing process since this is the only place where a #ow of clean grain is present. Nevertheless, this position has also a drawback. Grain #ow signals, measured at the end of the threshing process contain unconditionally the in#uence of disturbing machine dynamics. In practice, this means that feedrate variations and subsequently estimated yield variations, are smoothed reducing the economic interest of the resultant yield maps. The inverse simpli"ed linear transfer function makes it possible to reduce these latter errors and to improve immediately the results of further site-speci"c grain yield analysis.