A Modular 3D-Printed Inverted Pendulum.

Here we describe a simple modular 3D-printed design for an inverted pendulum system that is driven using a stepper motor operated by a microcontroller. The design consists of a stainless-steel pole that acts as the pendulum, which is pivoted at one end and attached to a cart. Although in its inverted configuration the pendulum is unstable without suitable control, if the cart travels backwards and forwards appropriately it is possible to balance the pole and keep it upright. The pendulum is intended for use as a research and teaching tool in the fields of control engineering and human sensori-motor control. We demonstrate operation of the design by implementing an observer-based state feedback controller, with augmented positional state of the cart and integral action, that can balance the pole in its unstable configuration and also maintains the cart at its starting position. When the controller is running, the pendulum can resist small disturbances to the pole, and it is possible to balance objects on its endpoint.