Decoupled multi-loop robust control for a walk-assistance robot employing a two-wheeled inverted pendulum
Journal
Machines
Journal Volume
9
Journal Issue
10
Date Issued
2021
Author(s)
Abstract
This paper develops a decoupled multi-loop control for a two-wheeled inverted pendulum (TWIP) robot that can assist user’s with walking. The TWIP robot is equipped with two wheels driven by electrical motors. We derive the system’s transfer function and design a robust loop-shap-ing controller to balance the system. The simulation and experimental results show that the TWIP system can be balanced but might experience velocity drifts because its balancing point is affected by model variations and disturbances. Therefore, we propose a multi-loop control layout consisting of a velocity loop and a position loop for the TWIP robot. The velocity loop can adjust the balancing point in real-time and regulate the forward velocity, while the position loop can achieve position tracking. For walking assistance, we design a decoupled control structure that transfers the linear and rotational motions of the robot to the commands of two parallel motors. We implement the designed controllers for simulation and experiments and show that the TWIP system employing the proposed decoupled multi-loop control can provide satisfactory responses when assisting with walking. ? 2021 by the authors. Licensee MDPI, Basel, Switzerland.
Subjects
Decouple
Inverted pendulum
Multi-loop control
Robust control
TWIP
Type
journal article