Provably Correct Sensor-Driven Path-Following for Unicycles Using Monotonic Score Functions

• Published in: 2023 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS) pp. 354 - 360
• Main Authors: Clark, Benton, Hariprasad, Varun, Poonawala, Hasan A.
• Format: Conference Proceeding
• Language: English
• Published: IEEE 01.10.2023
• Subjects: Angular velocity; Intelligent robots; Kinematics; Mobile robots; Robot kinematics; Robot sensing systems; State estimation
• ISSN: 2153-0866
• DOI: 10.1109/IROS55552.2023.10342233

This paper develops a provably stable sensor-driven controller for path-following applications of robots with unicycle kinematics, one specific class of which is the wheeled mobile robot (WMR). The sensor measurement is converted to a scalar value (the score) through some mapping (the score function); the latter may be designed or learned. The score is then mapped to forward and angular velocities using a simple rule with three parameters. The key contribution is that the correctness of this controller only relies on the score function satisfying monotonicity conditions with respect to the underlying state - local path coordinates - instead of achieving specific values at all states. The monotonicity conditions may be checked online by moving the WMR, without state estimation, or offline using a generative model of measurements such as in a simulator. Our approach provides both the practicality of a purely measurement-based control and the correctness of state-based guarantees. We demonstrate the effectiveness of this path-following approach on both a simulated and a physical WMR that use a learned score function derived from a binary classifier trained on real depth images.