Introduction

A technique for bringing an unstable system such as an inverted pendulum into equilibrium is presented. An Arduino Uno microcontroller programmed with a Proportional-Integral-Derivative (PID) algorithm is used to react to the fall of an inverted pendulum subject to gravity. Applied to an industrial problem, an algorithm used to gain control of an unbalanced pendulum could theoretically be converted to the task of transporting large, unstable materials. PID controllers are used to stabilize the velocity of rockets being launched into space, for cruise control in cars and temperature control systems buildings. This innovative algorithm accounts for 80 percent industrial and aerospace controllers. [2] The PID algorithm adjusts the frequency of a stepper motor to keep the pendulum upright when a force is applied and can maintain control for up to twenty minutes before human intervention is needed. As an extension from previous work by MXP students, the critical angle of an inclined plane at which the stepper motor would fail to maintain control was determined to be (6.60 ± 0.20)°. Further data was collected to prove the critical angle is independent of the length of the pendulum. For a preview of the mechanism in action, follow the link listed in the Conclusion section.