3D Print Open Source AI Robots

54 stars on GitHub. AcroMonk is a minimalist underactuated brachiating robot — it swings hand-over-hand across a horizontal ladder bar using just one quasi-direct drive (QDD) actuator and passive grippers. Published in IEEE Robotics and Automation Letters 2023 (featured in IEEE Spectrum Video Friday), it is the first brachiator with unactuated grippers that can perform more than two consecutive brachiation maneuvers. Source: https://github.com/dfki-ric-underactuated-lab/acromonk The robot is built from a single brushless QDD motor (MIT Cheetah-style), 3D-printed structural links, and simple passive hook grippers that rely on gravity and swing momentum for release and re-grasp. The absence of gripper actuators dramatically simplifies the mechanical design while making the control problem much harder — AcroMonk must time its swing precisely. Control methods include trajectory stabilization via TVLQR (time-varying LQR) and reinforcement learning. A full simulation environment (MuJoCo/PyBullet) is provided alongside hardware controllers. The kit is designed to be an affordable research testbed for underactuated locomotion research. Hardware: 1× quasi-direct drive brushless actuator (MIT Cheetah motor or equivalent), 3D-printed links and gripper hooks, horizontal ladder test bar. Open source under BSD-3-Clause license with accompanying IEEE RA-L paper. Build Guide Hardware build files, BOM, and assembly docs: github.com/dfki-ric-underactuated-lab/acromonk/tree/main/hardware