TurtleRabbit 2024 SSL Team Description Paper

TL;DR

The TurtleRabbit paper tackles the high entry barrier of RoboCup SSL by presenting a cost-efficient, open-source hardware and software stack that avoids custom PCBs. The approach leverages off-the-shelf components (Raspberry Pi 4, moteus controllers, drone motors) and additive manufacturing to build a functional SSL-capable robot, complemented by a 4-wheel omniwheel chassis and modular software featuring a PRM path planner, linear trajectory estimation, and role-based strategy. Key contributions include a detailed bill of materials with per-robot costs, an open hardware design repository, and initial autonomous capabilities (ball following and obstacle avoidance) with plans for scalable coordination and set plays. The work demonstrates a practical, replicable pathway for new teams to enter SSL, potentially lowering costs and accelerating education and entry into the league, while providing a foundation for more advanced future iterations.

Abstract

TurtleRabbit is a new RoboCup SSL team from Western Sydney University. This team description paper presents our approach in navigating some of the challenges in developing a new SSL team from scratch. SSL is dominated by teams with extensive experience and customised equipment that has been developed over many years. Here, we outline our approach in overcoming some of the complexities associated with replicating advanced open-sourced designs and managing the high costs of custom components. Opting for simplicity and cost-effectiveness, our strategy primarily employs off-the-shelf electronics components and ``hobby'' brushless direct current (BLDC) motors, complemented by 3D printing and CNC milling. This approach helped us to streamline the development process and, with our open-sourced hardware design, hopefully will also lower the bar for other teams to enter RoboCup SSL in the future. The paper details the specific hardware choices, their approximate costs, the integration of electronics and mechanics, and the initial steps taken in software development, for our entry into SSL that aims to be simple yet competitive.

Figures (6)

• Figure 1: Left: Render of the base plate with wheel arrangement and kicker (front right wheel and controller removed, exposing motor). Centre: Intermediate stage, plywood base plate. Right: completed, with PETG shell.
• Figure 2: The TurtleRabbit omniwheel drive with motor, controller, and motor mount.
• Figure 3: Left: Subwheels mounted on PETG wheel chassis. Right: Subwheel exploded view, with washers, MF52 2Z bearings, NBR $4.47mm \times 1.78mm$ X-ring, $2mm \times 10mm$ dowel pin.
• Figure 4: Left: Motor mount Right: Completed drive with motor mount, wheel, and controller.
• Figure 5: Path planner example for a robot moving to the ball with 20 random milestones. The other robots are seen as obstacles. While the thin lines show collision free paths between neighbouring milestones, the thick blue lines show the shortest path.