QualiGrain expert system for stored grain quality maintenance: planning optimal storage technical routes.

The maintenance of cereal grains quality is a complex problem due to the interaction between biotic and abiotic factors in stored grain ecosystem. The biotic factors (germination, insects, moulds and mites) give information on the quality of grain. The abiotic factors (time, temperature, moisture content, impurities and insecticides) influence the biotic factors dynamics and give information on grain storage condition. The planning problem is to control the abiotic factors in view to hold them in a safe storage condition. The QualiGrain preventive approach includes four steps: assessment of grain initial quality and condition, planning of optimal storage technical routes, monitoring of grain condition during storage and re-planning the storage technical route if the grain condition drifts out of safe storage conditions. In the planning module we use the biotic factors as state variables, the abiotic factors as control variables and the storage actions as actions of the plan. A storage action (dry, cool, clean, treat with an insecticide or select a bin) is executable if it is specified with a necessary and available equipment and/or chemical. "Dry grain using the medium dryer MD1 to reach 14.5% of moisture content" and "Store grain in the vertical bin VB4" are executable storage operations. The planning method is hierarchical, with two abstraction levels: i/ generation of the generic storage plans, ii/ refining the generic storage plans taking into account the time, the characteristics of available equipment and allowed consumables. An optimal storage technical route gives a planning of the storage actions to execute during the time with the estimated safe storage period after each action of the plan. A prototype of expert system QualiS© has been developed on Windows® personal computer. The advice afforded by decision support system have been validated by the human experts first and after in pilot scale experiments in Denmark and UK.