MODELING AND SIMULATION FOR CONTROL OF NUTRIENT APPLICATION IN CLOSEDGROWING SYSTEMS

In some European countries the year 2000 will be a target to enforce t he use of closed growing systems in greenhouses. Closed growing system s collect the surplus of water and nutrients and recirculate it to the crop after treatment. The design of a controller for water supply and nutrient application in closed growing systems is presented and discu ssed. Seasonal changes in the root mat or models which do not describe the real process precisely in all details, influence the general stab ility of the controlled supply process. It is shown, that robust perfo rmance and robust stability - as qualities of the controlled process - are feasible in these circumstances. Loopshaping proves to be a very useful design technique. Algorithm performance is tested in a simulati on procedure. Results of simulation tests show very good disturbance s uppression.