Real-Time Feedback Control Using Raspberry Pi: Reducing Barriers to Feedback Control Experiments

Feedback control has benefited society in many ways, but in order to fully realize the potential benefits, feedback control needs to be implemented in a wider range of physical systems and products. In order to achieve this goal, more control engineers need to get involved in working on control implementation details. There are at least two issues that prevent more controls engineers from getting involved in experiments on physical systems: conducting real-time feedback control experiments can be difficult and expensive. This work seeks to make it easier for controls engineers to get started with real-time experiments using low-cost hardware and open-source software. A Raspberry Pi mini-computer can be a cost-effective option for performing feedback control experiments, but programming it for real-time execution of a control law can be complicated. This paper makes two contributions to advancing broader use of Raspberry Pi’s in feedback control implementation: 1) verification of the ability of the Raspberry Pi to consistently execute the control law at hard real-time intervals on the order of one to two milliseconds and 2) an object-oriented C++ library to make it easier to write real-time code that mimics a classical controls block diagram