Solo 12 Quadruped

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Solo 12 is an open-source 12-degree-of-freedom quadruped robot developed by the Open Dynamic Robot Initiative (ODRI), a collaboration between New York University and the Max Planck Gesellschaft. Weighing 2.5kg and measuring 45cm x 30cm, Solo 12 is designed for locomotion research — with full joint torque control, high bandwidth actuation, and a BSD-3 open hardware license.

Source: https://github.com/open-dynamic-robot-initiative/open_robot_actuator_hardware

Kinematics

Solo 12 has four identical 3-DOF legs. Each leg provides hip abduction/adduction (Hip AA), hip flexion/extension (Hip FE), and knee flexion. The Hip AA joints allow lateral stabilization; the Hip FE and Knee joints control swing height and stride length. The robot can perform multiple full rotations in the knee and Hip FE joints — enabling stair climbing and fall recovery. Hip height at nominal standing position is approximately 24cm.

Actuators

Each of the 12 joints is driven by a custom brushless DC motor module developed specifically for ODRI robots: the TQ-rMD-X actuator module. These units combine a high-torque motor with a low-ratio gearbox for backdrivable, compliant behavior. All 12 motors communicate over a SPI daisy-chain to a custom Master Board, which connects to an external computer via Ethernet for real-time control at 1kHz.

Electronics

The Master Board (v2) is the central controller, managing all motor communication, IMU data, and user-space Ethernet connectivity. Six Micro Driver boards (two motors each) are stacked inside the body structure. A Lord Microstrain 3DM-CX5-25 IMU provides high-bandwidth inertial measurements for state estimation. The body structure's 3D-printed enclosure houses all electronics, with options for a Vicon motion capture marker plate.

3D Printed Parts

The body structure is entirely 3D-printed: front/back panels, top plates (master board and IMU variants), side panels, center plate, hip adapter blocks, LED covers, and stand forks. Print material is typically PETG or PLA at 0.15mm layer height.

Software

Solo 12 is compatible with the ODRI software stack including pybullet simulation, real-time_tools, and the MPC locomotion controller. The robot has been used in published research on model-predictive control, whole-body control, and reinforcement learning for legged locomotion. Commercial versions are available from PAL Robotics.

Install Notes

This is a hardware design repository — it contains CAD files, assembly guides, and mechanical specifications but no standalone software. The Open Dynamic Robot Initiative publishes the associated software stack separately at odri.dev and in the open-dynamic-robot-initiative GitHub org. Key software repos: robot_interfaces, solo, blmc_robots, master_board_sdk. The orobot Program code is a reference stub only; it will not drive hardware without the full ODRI stack installed and configured.