Hovering a ping-pong ball: A demonstration setup for teaching PID control

Proportional-Integral-Derivative (PID) controllers are essential in ensuring the stability and efficiency of numerous scientific, industrial and medical processes. However, teaching the principles of PID control can be challenging, especially when the introduction focusses on the underlying mathematical framework. To address this, we developed the PingPongPID - a visually engaging and interactive demonstration instrument designed to make the concepts of PID control more accessible to students. The PingPongPID features a colored ping-pong ball suspended within a transparent plastic tube by a fan whose voltage is controlled by a microcontroller running a PID algorithm. The ball’s height is measured in real-time by a laser distance sensor and the system continuously adjusts the fan voltage to maintain a set target height. The PingPongPID also connects to a computer allowing real-time data logging and visualization through a custom-built Python graphical user interface (GUI). The process of obtaining the three PID gain constants using both the trial-and-error and Ziegler-Nichols methods can be illustrated very nicely with the PingPongPID. In summary, the PingPongPID serves as a powerful educational tool allowing students to explore both the conceptual and practical aspects of PID control before delving into its mathematical foundations. We provide a complete assembly and user guide for the PingPongPID as well as the codes for the microcontroller and the Python GUI.