A Novel Assistive Controller Based on Differential Geometry for Users of the Differential-Drive Wheeled Mobile Robots

TL;DR

This paper introduces a differential geometry-based assistive control method for differential-drive wheeled robots, such as electric wheelchairs, enabling safe, smooth navigation without predefined target states, based solely on joystick inputs and vehicle states.

Contribution

It proposes a novel geometric control strategy using Darboux frame kinematics that does not require desired states, improving navigation safety and spontaneity for wheelchair users.

Findings

Successfully tested with different participants.

Achieved smooth trajectories under safety constraints.

Enhanced user control without predefined goals.

Abstract

Certain wheeled mobile robots e.g., electric wheelchairs, can operate through indirect joystick controls from users. Correct steering angle becomes essential when the user should determine the vehicle direction and velocity, in particular for differential wheeled vehicles since the vehicle velocity and direction are controlled with only two actuating wheels. This problem gets more challenging when complex curves should be realized by the user. A novel assistive controller with safety constraints is needed to address these problems. Also, the classic control methods mostly require the desired states beforehand which completely contradicts human's spontaneous decisions on the desired location to go. In this work, we develop a novel assistive control strategy based on differential geometry relying on only joystick inputs and vehicle states where the controller does not require any desired states. We begin with explaining the vehicle kinematics and our designed Darboux frame kinematics on a contact point of a virtual wheel and plane. Next, the geometric controller using the Darboux frame kinematics is designed for having smooth trajectories under certain safety constraints. We experiment our approach with different participants and evaluate its performance in various routes.