Thrust Direction Control of an Underactuated Oscillating Swimming Robot
This work addresses control challenges for autonomous surface robots in dynamic environments, representing an incremental improvement over existing inertial control methods.
The paper tackles the problem of controlling an underactuated oscillating swimming robot (Modboat) by developing a thrust direction control method that improves time-response and accuracy, enabling more compact maneuvers compared to prior methods.
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.