Holonomic Control of Arbitrary Configurations of Docked Modboats

TL;DR

This paper introduces a centralized control strategy for Modboats, enabling arbitrary docked configurations to move holonomically, effectively counteracting disturbances and controlling multiple motion parameters simultaneously.

Contribution

It presents a novel iterative potential-field based control method for docked Modboats, allowing arbitrary configurations to achieve holonomic control.

Findings

Controller performs well in experiments

Successfully controls surge, sway, and yaw simultaneously

Demonstrates robustness against disturbances

Abstract

The Modboat is a low-cost, underactuated, modular robot capable of surface swimming, docking to other modules, and undocking from them using only a single motor and two passive flippers. Undocking is achieved by causing intentional self-collision between the tails of neighboring modules in certain configurations; this becomes a challenge, however, when collective swimming as one connected component is desirable. Prior work has developed controllers that turn arbitrary configurations of docked Modboats into steerable vehicles, but they cannot counteract lateral forces and disturbances. In this work we present a centralized control strategy to create holonomic vehicles out of arbitrary configurations of docked Modboats using an iterative potential-field based search. We experimentally demonstrate that our controller performs well and can control surge and sway velocities and yaw angle simultaneously.