Robust State Observers for Two Wheeled Inverted Pendulum under wheel-slip

Abstract

Two Wheeled Inverted Pendulums (TWIP) are among the most agile wheeled robots; as such, they are the perfect choice for Unmanned Ground Vehicles (UGV) that need to perform tight turns. TWIP's parallel-wheels structure allows turning-on-the-spot, but makes them intrinsically unstable; as such they require a closed-loop controller to prevent toppling. Accurate estimates of the vehicle dynamical states are required at all times. TWIPs are often used only in undemanding environments as testbeds for the development and testing of new control strategies on nonlinear underactuated systems. This work is dedicated to the development of a complete suite of state observers to be used on TWIPs operating in challenging environments. In particular, the robustness of the estimates to temperature-related gyrometer biases and wheel slip events will be verified. The effectiveness of the algorithms will be demonstrated using a prototype TWIP designed to operate as an autonomous parcel-delivery robot in urban environments.