TITLE:
Implementation of Control Algorithms in Small Embedded Systems
AUTHORS:
Lars Bengtsson
KEYWORDS:
Bilinear Transformation, Euler Transformation, Microcontroller, Control System, PID Algorithm, Temperature Sensor, Set Value, Process Value, Plant
JOURNAL NAME:
Engineering,
Vol.12 No.9,
September
14,
2020
ABSTRACT: This work describes how a control algorithm can be implemented in a small (8-bit) microcontroller for the main purpose of merging embedded systems and control theory in electrical engineering undergraduate classes. Two different methods for discretizing the control expression are compared: Euler transformation and bilinear transformation. The sampling rate’s impact on the algorithm is discussed and theoretical results are verified by an application to a temperature control system in a heating plant. Four control algorithms are compared: PID and PI algorithms discretized with Euler and bilinear transformation, respectively. It is shown that for the heating plant used in this work, a bilinear PI algorithm implemented in a small 8-bit microcontroller outperforms a commercial controller from Panasonic. It is also demonstrated that all the derived algorithms can be implemented using integer calculations only, obviating the need for expensive and time-consuming floating-point calculations. This work bridges the gap between control theory equations and the implementation of control systems in small embedded systems with no inherent floating-point processing power.