Disturbance observer and ageing estimation for a temperature controlled food transporter

Abstract

Temperature control of a food transport system with an insulated cool box (ICB) can be efficiently provided by model predictive control (MPC). However, disturbances like solar irradiation or deterioration of the heat transfer coefficient α of the ICB are typically not detected by sensors. In this paper a disturbance observer for solar irradiation is used to design a fast sampled disturbance compensation obtaining a fast response of the system. Two specific characteristics of the disturbance are utilized to estimate α: 1) During nighttime solar irradiation has its minimum. 2) α declines at a very slow rate. The MPC, irradiation estimation, and α estimation are implemented with different sampling rates. This enables separate and robust estimation and efficient implementation. The system and control architecture is presented, the concept of the observer and estimation is given and simulation results demonstrate the performance of the concept.