Synchronized Robot: A PID Control Project with the LEGO Mindstorm NXT

Typical courses in introduction to controls are usually heavy in theory and light in practical application. In order to emphasize practical application in this type of course, such as the implementation of a PID controller, there are problems with most of the commonly used options. The first option is to provide the students with an approximate model of a system and have them use simulation to implement a PID controller. The simulation approach is limited because there is not an “actual system” to control and the model is likely oversimplified. A second option requires the instructor to create a control system that all students use. This approach is expensive, time consuming, and not all students have access to the system at the same time. A third possibility requires students to build their own system and then control it. The problem with this approach is that so much time is dedicated to mechanical and electrical design, while important control theory concepts are left out or deemphasized. A solution to these problems is providing the students with a LEGO Mindstorm NXT kit, which allows them to quickly design their system so they can focus on the application of control theory. These kits are inexpensive and can be used for other functions such as freshman orientation courses and outreach events when not being used for controls. In the Introduction to Control Systems Engineering course (ECE 4413) at the University of Oklahoma (OU), students were given a LEGO Mindstorm NXT kit and some brief training in the LabVIEW programming environment in order to complete a class project. The students implemented PID control algorithms to produce synchronized robots that tracked each other’s movement. Implementing PID control in LabVIEW without any built-in PID functions allows students to discover how the control algorithm works in a visual way. With this method, the likelihood of retaining the knowledge would appear to be much greater than modifying a built-in function while doing simulations. This paper will show how this project increased the students’ understanding of PID control. Pre-project and post-project quizzes are used to provide statistical evidence of improvement. Students’ perceived value of the project is also explored. Additionally, details of the project are provided so that other universities looking to emphasize practical application in their introductory controls course can replicate it.