YOU CAN BUILD THE SIX-AXIS MOTION PLATFORM THAT THROWS A SEAT AROUND
Six 750-watt servos driving a seat through every degree of freedom a flight simulator uses, and the creator put the controller design and firmware on GitHub under MIT.
RoboticsOpen-hardware
Built withESP32
- difficulty
- ●●●●●
- time
- weeks
- license
- MIT
- repo
- repo ACTIVE380 stars
●●●●● · weeks · MIT · 380 stars · repo ACTIVE
WHAT YOU’LL NEED
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COMPAREE VERDICT
This is a true six-degree-of-freedom Stewart platform: six AC servos arranged so that together they can tilt, roll, pitch, yaw, rise and slide, with no single actuator responsible for any one motion. Christopher Knauf built it for sim racing and published the controller, firmware and some CAD under MIT. The scale is what surprises — six 750-watt motors, each through a 50:1 planetary gearbox, driven by AASD-15A servo drives with differential step/direction signals. The desktop side is a C++ application doing 3D visualisation, motion cueing and hardware-in-the-loop telemetry from the game. Three things will determine whether this is for you. First, the published CAD covers only the mini variant and the motor mounts — the large steel frame in the footage is described in words, not supplied as CAD. Second, the new ESP32-S3 controller board is, by the author's own README, an untested prototype marked do-not-order; the videos show the earlier ESP32 generation. Third, and most important: the author warns this is heavy rotating machinery capable of serious injury or death, and independent emergency stop hardware has to be in place before it is ever powered. If you have the metalworking skill, the patience to follow an evolving controller design, and you take that safety warning seriously, this is a deep and well-documented project. If you were expecting a turnkey, validated build, this is not that yet.
IN THE REPO
GOOD TO KNOW
- —MIT licence — commercial use is allowed.
- —CAD covers the mini variant and motor mounts only. The large steel frame in the footage is welded and described in the README, not supplied as CAD.
- —Electronics have been redesigned since the 2019–2020 videos. The footage shows an earlier revision.
- —Firmware is present for the ESP32-S3 controller board and desktop C++ application for telemetry and motion cueing.
- —The README includes a safety warning that this is heavy rotating machinery capable of serious injury.
- —No complete bill of materials with prices — component list is partial and servo/gearbox costs are not documented.
Parts to buy
7 itemsFrom our check of the build. Exact quantities and part numbers are in the creator’s BOM.
Can I build this?
Build at your own risk. Projects involve tools, electronics and sometimes mains voltage — follow the creator’s safety notes.
Videos
Footage from 2019–2020 showing an earlier electronics revision. The current design uses a newer ESP32-S3 board.
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Start here
Navigation into the creator’s own docs — we don’t rewrite the guide, we route you to the source.
- 1.Read the safety warning in the README and plan emergency stop hardware before anything else (The author's own warning about serious injury risk is the first thing to take in.)
- 2.Review the CAD files and understand what is supplied and what is not (CAD covers the mini variant and motor mounts. The large steel frame is described in the README, not supplied as CAD.)
- 3.Check the electronics schematic and decide whether to build the custom PCB or wire a dev board (The new ESP32-S3 board (r13) is an untested prototype the author marks do-not-order; read hardware/pcb/6DOF2_BOARD.md and the firmware TODO before committing to any controller.)
- 4.Source the servos, gearboxes and drives — these are the long-lead and high-cost items(The controller PCB has a JLC BOM and buying guide, but there is no priced shopping list for the servos, gearboxes, drives and frame — the README lists them only as a description of the original build.)
Resources
Documentation, files and community threads for this build — we link straight to the original sources and never rehost the creator’s files.
KNOWN ISSUES
- The CAD does not include the large welded steel frame — you are fabricating that from the written description in the README, or redesigning it entirely.
- The video footage is from 2019–2020 and shows an earlier electronics revision. The current design uses a newer ESP32-S3 board, so what you see is not what you will build.
- No complete bill of materials with prices — you will be sourcing six 750W servos, six planetary gearboxes, and six servo drives without a verified parts list or cost estimate.
- The desktop C++ application for motion cueing and telemetry is part of the build — this is not just firmware, you are also compiling and configuring software on the PC side.
- Emergency stop hardware is not optional. The author's own warning is that this machine can seriously injure you, and you must have a working e-stop before the first power-on.
- The servo drives take step and direction as differential (RS-422 style) signals through line-driver chips on the controller board — if you have never wired differential signalling before, that will be a learning curve.
Is the full-size steel frame included as CAD?
No. The published CAD covers the mini variant and the motor mounts. The large steel frame in the footage is welded and described in the README, not supplied as CAD files.
Can I use this commercially?
Yes, the licence is MIT and allows commercial use.
What is the total cost?
Not documented. The README describes the original hardware — six 750 W AC servos, six 50:1 planetary gearboxes, six AASD-15A drives, rod-end linkages and a steel base — but explicitly not as a priced shopping list. Price those parts yourself before committing; they are the bulk of the cost, before steel and emergency-stop hardware.
Does the video match the current design?
No. The video is from 2019–2020 and shows an earlier electronics revision. The current design uses a newer ESP32-S3 board.
Community builds
No community builds yet — be the first, we feature the best ones.
Discussion1
FROM THE COMPAREE TEAM
Six 750-watt servos on the full-size rig, or six hobby servos on the Mini-6DOF desktop version. If you were starting today, which would you build first — and would you wait for the new controller board to be tested?
Christopher Knauf
Christopher Knauf built this Stewart platform for sim racing in 2020 and has kept developing it since, publishing the controller design, firmware, desktop app and some CAD under the MIT licence.
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DISCLAIMER
- Comparee is not the author of the projects featured here. All rights to each project belong to its creator — every page links to the original source, and we never host creators’ files.
- Information is provided without warranty and may become outdated as projects evolve. Prices are indicative bands only — always check the creator’s parts list for current costs.
- Building and operating any project is at your own responsibility. Protective equipment, safe workshop practice and compliance with local regulations are the builder’s responsibility.
CompareeTEAM1mo agoedited
Practical notes from our verification: the repository is active (last updated in September 2026), the licence is MIT, and the README is unusually honest about status. The newest controller, the ESP32-S3 based r13 PCB, is marked as an untested prototype that you should not order, and the author says not to run the current firmware and board combination on a powered platform. The videos show the original build (the linked one dates from December 2019), not the current electronics. The original full-size rig used a 31-inch, half-inch steel base plate, six 750-watt AC servos with 50:1 planetary gearboxes and AASD-15A drives; that hardware is described in the README rather than supplied as a complete shopping list. There is also a desktop-scale Mini-6DOF variant with hobby servos, which is the sensible place to start. Above all: this is heavy rotating machinery, and independent emergency stop hardware must be in place before anything is powered. Correction (4 October 2026): we re-checked this page line by line against the project's own repository, documentation and videos, and fixed errors in earlier versions.