Thrust Direction Control of an Underactuated Oscillating Swimming Robot

TL;DR

This paper introduces a thrust direction control method for the Modboat robot, enhancing its responsiveness and maneuverability in dynamic environments through experimental validation and an improved controller extension.

Contribution

It presents a novel thrust direction control approach that improves response time and accuracy, and extends the controller to address actuator velocity limitations.

Findings

Enhanced maneuverability compared to prior methods

Improved response time and control accuracy

Successful experimental validation

Abstract

The Modboat is an autonomous surface robot that turns the oscillation of a single motor into a controlled paddling motion through passive flippers. Inertial control methods developed in prior work can successfully drive the Modboat along trajectories and enable docking to neighboring modules, but have a non-constant cycle time and cannot react to dynamic environments. In this work we present a thrust direction control method for the Modboat that significantly improves the time-response of the system and increases the accuracy with which it can be controlled. We experimentally demonstrate that this method can be used to perform more compact maneuvers than prior methods or comparable robots can. We also present an extension to the controller that solves the reaction wheel problem of unbounded actuator velocity, and show that it further improves performance.