Modular approach for motion control design of three-dimensional two-wheeled inverted pendulum

This article reports a mechatronic project of a two- wheeled inverted pendulum system in a modular approach. A mathematical model for the three-dimensional plant was obtained by using Lagrange mechanics, and a turning control module was incorporated so the system could perform free movement along the plane. This controller allowed the system to achieve rapid turning speed responses, with rising times less than 1s, overshoots of around 4% and null steady-state error. The overall system was then simulated so the reference signals were generated by different methods using five approaches: (i) direct leaning reference input with turning speed input; (ii) direct longitudinal speed reference input with turning speed input; (iii) limited speed by bounding the leaning reference input at high speeds; (iv) independent speed control for each wheel; and (v) automatic trajectory following. A stabilization time of 5.5s for the maximum longitudinal speed of 5.5m/s was obtained by using the bounded torque approach. The results showed that every performance requirement in terms of each control module were fulfilled when working with non-extreme situations.