Position Dependent Control (PDC) of plant production

Authors

• Hannu E. S. Haapala Department of Agricultural Engineering and Household Technology, P.O. Box 27, FIN-00014 University of Helsinki, Finland

DOI: https://doi.org/10.23986/afsci.72612

Abstract

The aims of this work were to get answers to the following three questions: (1) What are the potentialities of coordinate-based field crop production? (2) What are the requirements for the method of attaching field crop information to a coordinate system? (3) What are the possible solutions? The work was focused on the effects of positioning quality. In PDC (Position Dependent Control) positioning is needed to target the inputs and to relate inputs and outputs accurately to each other. Systems analysis was used to accomplish a mathematical model of the position dependent control system. The model developed describes a system which consists of models for the positioning method and the target. An accuracy requirement of ±5 meters for N-fertilization was set with the developed model. The results from Keimola gave information on the variability of soil and wheat yield. Regressions for individual input variables and multiple regressions calculated for whole sample lines (á 50 m) were low (r2 <0.11 and r2 <0.15). Attachment of the variation information to coordinate gave regression estimates with r2's up to 0.99. Positioning tests in Viikki show adequate accuracy (uncertainty ellipse <25 m2 @95%) of DGPS (Differential Global Positioning System) satellite positioning. DGPS was tested both in an accurately measured test route and field tests during drilling. Road tests in covered locations were also made. PDC of plant production gives accurate control over the position fixed production process. The enhanced controllability can be used to adjust the production to meet environmental or economical criteria. The variable requirements for positioning can be set with simulation. The simulations need valid models for the production in the target area. GPS satellite navigation together with a GIS (Geographical Information System) database is a potential technics for the realization of this local control.