A multirate adaptive technique for temperature control in greenhouses

摘要

In this paper, a new adaptive technique is presented, for temperature control of greenhouses, for which, heat capacity, heat transfer coefficient and thermocouple's dead-time vary with the ventilation as well as the velocity of the air in the greenhouse. The proposed technique relies on multirate sampling of the greenhouse temperature. The sampled-data, obtained by this procedure, are appropriately used for feedback control, thus providing a globally stable indirect adaptive scheme. This scheme estimates the unknown parameters of the process on-line, from sequential data of the greenhouse temperature and the power of electrical heating, which are recursively updated within the time limit imposed by a fundamental sampling period. The effectiveness of the proposed technique is demonstrated by several simulation results.