humanoidrobots.systems

anninrobotics/ar4 · spec sheet

Annin AR4 specs

Open-plan, low-cost 6-DOF desktop industrial-style robot arm by Chris Annin, programmable via its HMI, Python or ROS.

Maker
Annin Robotics
Class
Arm
Status
Active
Availability
Kit
Country
United States
Level
L1 Compiled
01

Media

3 items · credited and licensed
AR4 studio render, three-quarter front viewrender
Studio render of the published URDF (xacro), the model's zero pose. Geometry only; colours are the model's own materials.Rendered by Hyperspawn from Annin-Robotics/ar4_ros_driver (MIT)license: Hyperspawn rendergithub.com
AR4 studio render, side viewrender
Side view of the same URDF (xacro) render, the model's zero pose.Rendered by Hyperspawn from Annin-Robotics/ar4_ros_driver (MIT)license: Hyperspawn rendergithub.com
4 s turntable of the URDF (xacro) studio render.Rendered by Hyperspawn from Annin-Robotics/ar4_ros_driver (MIT)license: Hyperspawn rendergithub.com
02

Specifications

1/12 fields sourced
Annin AR4 specifications
Heightspecs.heightCmunsourced
Massspecs.massKgunsourced
Degrees of freedomspecs.dof6
Payloadspecs.payloadKgunsourced
Top speedspecs.speedMpsunsourced
Runtimespecs.runtimeMinunsourced
Battery capacityspecs.batteryWhunsourced
Pricespecs.priceUsdunsourcedTotal build cost just over $2,000 USD (varies with part sourcing)
Actuatorsspecs.actuatorsunsourced
Computespecs.computeunsourced
Sensorsspecs.sensorsunsourced
Year introducedyearunsourced
Licenselicense.hw / .sw / .docsHardware: LicenseRef-Annin-Robotics-NC-1.1Software: MIT AND LicenseRef-Annin-Robotics-NC-1.1

Note · Chris Annin declared the design complete with the final Mark 5 revision. ar4_ros_driver is MIT; ar4-hmi uses the Annin Robotics Open Source Non-Commercial License v1.1 (GitHub NOASSERTION), recorded as LicenseRef-Annin-Robotics-NC-1.1. The design files (STLs in ar4-hmi) fall under the same non-commercial license, so hw is LicenseRef-Annin-Robotics-NC-1.1: no commercial use, no rehosting. The current build is MK5 (AR4-MK5 build manual v1.1 on the downloads page). STL files are free; SolidWorks/STEP CAD for MK5 is sold separately ($99). sim=true refers to URDF in the ROS driver repo.

03

Openness

method
90 / 100Open hardware
ArtifactPublicWeightPoints
CADopenness.cadyes2525
Bill of materialsopenness.bomyes2020
Sim model (URDF/MJCF)openness.simyes2020
Firmwareopenness.firmwareyes1515
Softwareopenness.softwareyes1010
Trained policiesopenness.policiesno100
score = Σ weight × public90
04

Build package

v0.1.0 · full guide
BOM lines
64
Parts (qty)
127.12
Priced BOM
$699
Fab parts
51
Print time
—
Material
—
Build steps
22
Est. assembly
—
Safety steps
7
Vendors
2

BOM by category · USD from priced lines

CategoryLinesQtyUSD
Structure2639699
Cabling1025.12—
Fasteners732—
Actuators66—
Electronics610—
Power33—
Sensors39—
Other22—
Compute11—

Offers in GLOBAL · US from 2 vendors

Subsystems · assembly groups

GroupStepsMinSafety
Fabrication2——
Base enclosure4—2
J1 base3——
Arm5——
Firmware2——
First motion3—3
Calibration2—1
Software1—1

Fabrication: CNC ×26 · FDM print ×25

Firmware

Targets
Teensy 4.1 (arm: step/dir to 3x DM332T + 3x DM320T, 6 motor encoders, calibration inputs pins 26-31, E-stop pin 39), Arduino Nano or Mega (optional gripper / IO board, 5 V)
Repo
github.com/Annin-Robotics/ar4-hmi
Calibrate
AR4 HMI, Config Settings tab: 'Calibrate J1 Only' ... 'Calibrate J6 Only' or 'Auto Calibrate' drive each joint to its Hall sensor (J1-J3) or limit switch (J4-J6) and back to zero; trim per-joint calibration offsets (degrees, opposite sign of the measured error) and save. 'Force Cal Home' / 'Force Cal Rest' exist for setup only. ROS 2: `ros2 launch annin_ar4_driver driver.launch.py ar_model:=mk5 calibrate:=True` and `/calibrate_mask` service; offsets via CAL_OFFSET_DEG in the ROS Teensy sketch.
Notes
Two firmware lines: the Annin HMI sketch (AR4_teensy41_sketch; v7.0 on the downloads page, v6.3 in Annin-Robotics/ar4-hmi, needs Encoder, ModbusMaster, ArduinoJson) and the ROS driver sketch (annin_ar4_firmware/AR4_teensy v2.1.0, needs Bounce2). They are not interchangeable; reflash when switching. Steps per degree for MK4/MK5 per the step-calculation sheet: J1 88.89 (10:1 x 4), J2 111.11 (50:1), J3 111.11 (50:1), J4 99.56 (16:1 x 2.8), J5 43.72 (8 mm lead screw, 1600 microsteps), J6 44.44 (20:1). Servo gripper runs on an Arduino Nano sketch (AR4_nano_sketch).

Caveats · stated by the package

  • Upstream pins: AR4-MK5 Robot Manual v1.1 (version log 6/8/26; PDF at anninrobotics.com, 390 pages) as of 2026-09-25; AR4-MK5-3D-Print-Files.zip (2026-06 upload); AR4-MK5-motor-step-calculations.xlsx; downloads and robot-kits pages as of 2026-09-25 (Teensy sketch v7.0, HMI 7.0); Annin-Robotics/ar4-hmi@ed2abfd3a33340745dd4e2e114a7b1ac6761fc29 (2025-11-19, HMI 6.3.1, Teensy sketch v6.3); Annin-Robotics/ar4_ros_driver@6a3ebb11cedab12cd1d29b41d63aa270a008ab8b (2026-06-09, Teensy firmware 2.1.0, ar_model mk1-mk5)
  • Only kit-level USD prices are published: MK5 Combo Kit $1,189, Aluminum Parts Kit $699, Hardware Kit $319, Electrical Parts Kit $229, Pneumatic Gripper Parts Kit $139, Servo Gripper Parts Kit $74.50, MK5 CAD (SolidWorks/STEP) $99. Individual parts, the StepperOnline motor/driver/PSU package and printed parts are unpriced here. Only the aluminium kit line carries a price, so any computed total is far below the real cost (robots.ts note: just over $2,000).
  • The main robot BOM does not list a power supply. The 24 V 8 A adapter appears in the pneumatic gripper BOM and ships in the StepperOnline package; it is a mains brick feeding a 5.5 mm jack.
  • Motor part numbers disagree inside the manual: the motor BOM pages list J2 23HS22-2804D-YGS50-AR4 and J6 14HS11-1004D-EGS20-AR4, while the DIP-switch table lists 23HS22-2804D-HG50 and 14HS13-0804D-PG19 (0.92 A). The BOM SKUs are used here; set the J6 driver current for the motor you actually receive.
  • The manual cover says Version 1.0 but its version log records 1.1 (6/8/26: new J3 sensor mount, belt tension text). Build-manual PDFs are replaced on the downloads page without changelogs beyond that log.
  • GitHub lags the website: ar4-hmi holds HMI 6.3.1 and Teensy sketch v6.3 (2025-11), while anninrobotics.com offers HMI 7.0 and sketch v7.0 (2026-07). The sketch and HMI versions must match.
  • The ROS driver README still lists ar_model options up to mk4, but driver.launch.py accepts mk5 and defaults to it. ROS use needs the separate annin_ar4_firmware sketch.
  • Licensing: ar4-hmi and the design files are under the Annin Robotics Open Source Non-Commercial License v1.1 (no commercial use; design files may not be redistributed or rehosted). Only ar4_ros_driver is MIT. STL files are free; SolidWorks/STEP CAD for MK5 is sold ($99).
  • Fully printed builds are possible but the J4 main shaft must be aluminium tube, several large parts must be split and epoxied, and the manual notes belt tension cannot reach aluminium-build levels.
  • Fastener table lists 'M3 x 6 Button Head screw' and 'M3x6 Button head' as separate one-off lines; both are kept. The page 28 table is grouped here into sets, counts unchanged.
  • No trained policies or datasets for AR4 were found on Hugging Face (search 2026-09-25).

Package anninrobotics/ar4@0.1.0 · upstream AR4-MK5 Robot Manual v1.1 (version log 6/8/26; PDF at anninrobotics.com, 390 pages) as of 2026-09-25; AR4-MK5-3D-Print-Files.zip (2026-06 upload); AR4-MK5-motor-step-calculations.xlsx; downloads and robot-kits pages as of 2026-09-25 (Teensy sketch v7.0, HMI 7.0); Annin-Robotics/ar4-hmi@ed2abfd3a33340745dd4e2e114a7b1ac6761fc29 (2025-11-19, HMI 6.3.1, Teensy … (full pins in caveats) · 16 package sources

05

Models, repositories, links

7 links
06

Videos

2 tagged · 0 from the maker's channel
Build Your Own Industrial Robot, AR4 6-Axis Open-Source Arm - Low Cost, Python ProgrammableChris AnninOfficial embedyoutube.comAnnin RoboticsAnnin AR4
AR4 MK5 Open Source Robot Arm | 6DOF Arduino Python ROS2 Automation RobotChris AnninOfficial embedyoutube.comAnnin RoboticsAnnin AR4
07

News and papers

0 stories · 0 papers

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08

Sources

last checked 2026-09-25
  1. [1]Annin downloads: AR4-MK5 build manual, STLs, softwareanninrobotics.com/downloads/checked 2026-09-25
  2. [2]ar4-hmi LICENSE.txt (Annin Robotics Open Source Non-Commercial License v1.1)github.com/Annin-Robotics/ar4-hmi/blob/main/LICENSE.txtchecked 2026-09-25
  3. [3]Annin Robotics siteanninrobotics.com/checked 2026-09-24
  4. [4]Hackster: AR4 Mark 5 final revisionhackster.io/news/chris-annin-calls-the-open-source-ar4-robot-arm-done-with-the-new-final-mark-5-revision-62b51e0ae555checked 2026-09-24
  5. [5]Annin: ~$2000 build costanninrobotics.com/docs/what-6-axis-robot-arm-models-do-you-recommend-for-around-2000-usd/checked 2026-09-24
09

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Cite this page

humanoidrobots.systems. “Annin AR4 specs.” Hyperspawn, data revision 2026-10-08. https://humanoidrobots.systems/anninrobotics/ar4

Machine-readable: /data.json (record anninrobotics/ar4).