Solo12 is an open-source 12-DOF quadruped robot from the Open Dynamic Robot Initiative (ODRI), a collaboration between MIT, LAAS-CNRS, NYU, and MPI-IS to provide the legged-locomotion research community with an affordable, reproducible platform for dynamic control research.

The robot has four legs, each with three degrees of freedom (hip abduction/adduction, hip flexion/extension, and knee), actuated by ODRI's open-source brushless direct-drive actuator modules. Direct-drive transmissions give the robot high-bandwidth torque control and transparent dynamics — critical for whole-body MPC, reinforcement learning, and contact-rich locomotion experiments that are difficult or impossible on geared quadrupeds.

Solo12 has been used in dozens of published locomotion papers studying bounding gaits, stair climbing, reactive balance control, sim-to-real reinforcement learning, and model-predictive control. The full hardware and software stack — actuator PCBs, mechanical CAD, master board firmware, real-time control interface, and Pinocchio-based dynamics — is published under BSD-3-Clause, making Solo12 one of the most accessible research-grade quadrupeds available.

This program provides cloud-side locomotion commands (stand, sit, directional walking, trot, emergency stop) that relay to the onboard controller over WebSocket. The hardware requirement is a Raspberry Pi 4 acting as the high-level controller; the real-time low-level control loop runs on the master board over EtherCAT/SPI to the 12 actuator modules.

Credit to the Open Dynamic Robot Initiative consortium (LAAS-CNRS, MPI-IS, NYU, MIT) — upstream repository at https://github.com/open-dynamic-robot-initiative/open_robot_actuator_hardware under BSD-3-Clause.

Build Guide

Step-by-step assembly instructions for the Solo12 quadruped: Solo12 hardware README

Printing

Solo12 is a research-grade direct-drive quadruped — most of the robot is custom electronics, machined aluminium, and ODRI actuator modules, so the 3D-printed set is intentionally small (this is the correct, complete print set, not a partial one). The 11 parts below are the Solo12-specific printable components, curated from the much larger ODRI open_robot_actuator_hardware repo (which contains 200+ STLs spanning tools, jigs, and other robot configurations). PLA/PETG, ~214 cm³ total.

Leg hip modules — print one per corner (4, all distinct):

• solo12_hip_fe_fl (front-left), solo12_hip_fe_fr (front-right), solo12_hip_fe_hl (hind-left), solo12_hip_fe_hr (hind-right)
• These are the hip flexion/extension housings; each corner is a separate handed part — print all four.

Body frame — print one each (5):

• body_structure_center, body_structure_side, body_structure_top_imu (top plate with IMU mount)
• hip_adapter (mounts the hip modules to the body)
• led_cover (status-LED cover for the NeoPixel ring)

Assembly stand (accessory — 2):

• stand_foot and stand_fork form a benchtop stand/cradle used to hold the robot during assembly and calibration. This is an accessory/jig, not part of the walking robot — print it if you want the stand, skip it otherwise.

Not printed: the 12 ODRI brushless direct-drive actuator modules, 6 micro-driver PCBs, master board, IMU, timing belts, bearings, and machined plates are all sourced/fabricated per the BOM — only the parts above are 3D-printed.