Two-Wheeled Inverted-Pendulum Self-Balancing Robot with LQR or PID Control

The two-wheeled inverted pendulum (WIP) is an unstable nonlinear system used in industrial and academic applications. Two control methods for WIP-based self-balancing robot are developed, implemented in Matlab-Simulink and tested by simulation with good results. These methods are: i) LQR control with state observer to stabilize the pendulum vertical-angle and to track a desired motion trajectory, and ii) PID control for vertical-angle stabilization. An experimental prototype of WIP self-balancing robot with only the PID vertical-angle control is designed, implemented, and experimental tested on surfaces with different friction coefficients, proving good vertical-angle stabilization.