Skip to content
buildrobots.io
LearnStart

HumanoidROBOTISKR

ROBOTIS OP3

Small 20-DOF open-platform humanoid (~51 cm, 3.5 kg) built on Dynamixel XM430 servos and an Intel NUC, with open ROS software and URDF.

activeBuyL2 Sim-verifiednot buildable

Difficulty index

9.5/13
9.5
Index breakdown
Classhumanoid+5
Costunknown · midpoint+1.5
DOF20 DOF+2
Partsunknown · midpoint+1
How the index works

Top of the ladder. This robot lives on the humanoid domains.

Specimen photographs

5 items
  • ROBOTIS OP3 studio render, three-quarter front view
    Studio render of the published MJCF, the model's zero pose. Geometry only; colours are the model's own materials.Rendered by Hyperspawn from mujoco_menagerie/robotis_op3 (Apache-2.0) · Hyperspawn render · source
  • ROBOTIS OP3 studio render, side view
    Side view of the same MJCF render, the model's zero pose.Rendered by Hyperspawn from mujoco_menagerie/robotis_op3 (Apache-2.0) · Hyperspawn render · source
  • 4 s turntable of the MJCF studio render.Rendered by Hyperspawn from mujoco_menagerie/robotis_op3 (Apache-2.0) · Hyperspawn render · source
  • [ROBOTIS OP3] 두발로 걷는 로봇(ROBOT) 휴머노이드ROBOTIS · official video, embedded · source
  • ROBOTIS OP3 Read Write DemoROBOTIS · official video, embedded · source

Spec card

7/13 known
Degrees of freedom
20
Height
51 cm
Mass
3.5 kg
Battery
36.6 Wh
Actuators
20x Dynamixel XM430-W350-R
Compute
Intel NUC i3, 8GB RAM
Sensors
Logitech C920 camera, 9-axis IMU

Not in the registry: payload, speed, runtime, price, bom total, part count. Left blank rather than guessed.

What you learn building it

  • +Whole-body control
  • +Dozens of actuators on one bus
  • +Balance and fall handling
  • +Safe bring-up of a full-size machine
  • +Reading and flashing open firmware
  • +Testing in simulation (URDF/MJCF) before touching hardware

Openness

45/100
  • not publicCAD
  • not publicBOM
  • publicFirmware
  • publicSim model
  • publicSoftware
  • not publicPolicies

Score 45/100 computed from what is public: CAD 25, BOM 20, sim 20, firmware 15, software 10, policies 10. Software license: Apache-2.0.

Repos & models

URDF ↗MJCF ↗MuJoCo Menagerie ↗
SiteDocs

Build it

Closed hardware. Buy link only.

humanoidrobot.build/robotis/op3 · Closed hardware. Buy link only.

Simulate

Load it in the browser simulator and train a policy before building.

Open on humanoidrobots.training ↗

Next rung

None. This is the top. Find people building it on humanoidrobots.team.

This is the top of the ladder.

NoteBattery 11.1V 3300mAh LiPo (~36.6 Wh computed). e-Manual notes a 2025 ROS 2 re-release. Original release year and CAD availability not verified in fetched sources.

Sources

  1. [1]ROBOTIS e-Manualchecked 2026-09-24
  2. [2]Official repochecked 2026-09-24