Auto-assembled, not yet reviewed

Upkie

Wheeled biped that balances, build-it-yourself.

Reproducibility83/100Strong source coverage, unverifiedCADBOMWIREFWBUILDLICREPHow it is computed
Upkie open-source 6-DoF wheeled biped robot, 3D render from upkie.urdf
full robot 3D · upkie.urdf

About Upkie

Upkie is an open-source wheeled biped that balances on two wheels using mjbots actuators, a Raspberry Pi 4 with a pi3hat CAN and IMU interface, RYOBI-compatible battery power, RC wheels and 3D-printed torso and leg hardware. The main software repository holds the balancing agents and documentation, and the upkie_description repository has the full robot URDF and meshes. The bill of materials lists quantities and suppliers but no complete total.

Licenses

Hardware
Apache-2.0
Software
Not published
Docs
Not published

Degrees of freedom

6 DoF wheels 2hipKnee 4

Breakdown source

Wheeled bipedsource

How to build Upkie

5 steps

Steps marked Motari summary condense the linked source; follow the source for exact instructions. Upstream step marks a step taken from the linked guide.

  1. Print the structure

    Print the torso and leg parts in PETG at 0.2 mm layers from the upkie_parts 3MF or STL files, then press in the heat-set inserts. Upstream says a full build takes 60+ hours of 3D printing.

    Motari summaryupkie.github.io/upkie/build-your-own.html

  2. Configure the actuators

    Set the ID of each of the four qdd100 hip and knee servos and the two mj5208 wheel servos, then test each one with moteus_tool through the pi3hat.

    Motari summaryupkie.github.io/upkie/build-your-own.html

  3. Assemble the legs and wheels

    Screw each mj5208 wheel motor to its printed wheel hub and lock the wheel on with the hex coupler, then assemble the legs around the qdd100 hip and knee servos.

    Motari summaryupkie.github.io/upkie/build-your-own.html

  4. Wire the pi3hat

    Mount the pi3hat on the Raspberry Pi 4 and daisy-chain each leg's hip, knee and wheel servos to it, powered through the power distribution board from an 18V RYOBI-compatible battery.

    Motari summaryupkie.github.io/upkie/build-your-own.html

  5. Run the balancing agent

    Zero the servos, start the pi3hat spine and run the balancing agent, checking that the wheels respond in the air before putting the robot on the ground.

    Upstream stepgithub.com/upkie/upkie/blob/a1914e7a02dd732ca71c82dc1fc2f8be...
Print time60 h
Assembly timenot published

Wiring, power and firmware are safety-relevant and shown for reference only. Check them against the source before building.

Upkie bill of materials

11 rows

Cost to build

The sources do not publish a cost total. The rows below are what they list, without a sum.

Upkie parts, as the source lists them (read 2026-06-07). Prices are the source's, not checked against vendors.

Upkie bill of materials
PartQtySpecSourceConfidence
mjbots qdd100 servoHip and knee quasi-direct-drive servos
4qdd100 servo beta 2+ per Upkie wiki BOM
mjbotsprice not listedUpkie wiki Bill-of-materials.md lines 3-38
high
moteus developer kit wheel actuatorWheel drive actuators
2moteus developer kit r4.11+ per Upkie wiki BOM
mjbotsprice not listedUpkie wiki Bill-of-materials.md lines 3-38
high
mjbots pi3hatRaspberry Pi CAN-FD and IMU interface
1pi3hat r4.4b+
mjbotsprice not listedUpkie wiki Bill-of-materials.md lines 3-38
high
mjbots power distPower distribution board for actuators and electronics
1power dist r4.3b+
mjbotsprice not listedUpkie wiki Bill-of-materials.md lines 3-38
high
Raspberry Pi compute stackBalancing host computer and supporting storage/cooling
1Raspberry Pi 4 Model B, microSDXC card, aluminum heat sink, micro HDMI cable
Raspberry Pi / online retailprice not listedUpkie wiki Bill-of-materials.md lines 3-38
high
RYOBI-compatible battery and contactsRobot battery and battery-contact hardware
1RYOBI 18V-compatible battery plus 2 battery contact springs and XT90-S connector
online retail / Digi-Keyprice not listedUpkie wiki Bill-of-materials.md lines 3-38
high
RC wheels and 17 mm hex couplersTwo RC wheels plus matching couplers and wrench
2112 mm outer diameter, 80 mm inner diameter, 17 mm wheel-drive hex, 12 mm axle hole
online retail / 3D-printed wrenchprice not listedUpkie wiki Bill-of-materials.md lines 46-55
high
CAN and power cabling/connectorsCommunication and power cable set
1JST PH-3 CAN connectors, XT-30 connectors, leg power cables, torso power cables, 26 AWG comms wire, 14 AWG power wire
mjbots included connectors / online retailprice not listedUpkie wiki Bill-of-materials.md lines 3-38 and Cables.md lines 1-43
high
Fasteners, inserts, spacers and heat shrinkMechanical/electrical consumables for assembly
1M2.5/M3 screws, M2.5/M3 heat-set inserts, M2 hex spacers, heat-shrink tubing, terminator resistors
online retail / included with pi3hatprice not listedUpkie wiki Bill-of-materials.md lines 3-38
high
3D-printed torso and leg partsPrinted structural parts and wheel hub
1PETG/rigid printed parts with source quantities and print settings from wiki
3D print yourself from upkie partsprice not listedUpkie wiki 2)-3D-printing.md lines 7-55
high
Optional RTC moduleOptional DS3231 real-time-clock module
0DS3231 chip
online retailprice not listedUpkie wiki Bill-of-materials.md lines 40-44
high

Rows from the source's own parts list 6

Bill-of-materials.md@6df8cbamarkdown

Source rowQtyPrice and vendorLine
Upkie main BOM table
source table quantities
Upkie wiki supplier columnno price listed
L3
Upkie optional RTC module
1 optional
online retailno price listed
L40
Upkie RC wheel requirements
2 wheels
online retailno price listed
L46

2)-3D-printing.md@6df8cbamarkdown

Source rowQtyPrice and vendorLine
Upkie 3D printed parts
source-listed printed part quantities
self-printno price listed
L7

Cables.md@6df8cbamarkdown

Source rowQtyPrice and vendorLine
Upkie cable specifications
source-listed cable specs
self-assemble / online retailno price listed
L1

6)-Assembly.md@6df8cbamarkdown

Source rowQtyPrice and vendorLine
Upkie assembly prerequisites
Upkie wikino price listed
L1

Upkie source files

12 files

Files stay in the upstream repository under their own licenses; these links open them there. The 3D model on this page is Motari's conversion of the file named under Simulation.

Upkie in simulation

Robot description files a simulator or CAD tool can load, linked at the commit they were found.

The 3D specimen on this page is converted from urdf/upkie.urdf at 94735fb.

Builds of Upkie

0 reviewed

No reviewed builds of Upkie yet.

A build log records the evidence (photos, a video, your repository), what the build cost, how long it took and what you changed. Each one is checked by Motari (until a maintainer claims this page) before it shows here, and reviewed builds count toward the reproducibility score.

Sources and provenance

Sources

Last push to upkie/upkie: 2026-09-30 (checked 2026-10-01)

How this page was made

Assembled from public sources on 2026-05-11, not yet reviewed by the maintainer. Each figure links to where it is stated; a value the sources do not state reads "not published". Last source review: 2026-06-07 Upkie wiki BOM and upkie_description URDF.

Original files stay intact and separately licensed; Motari adds only the summary on this page. Maintainer? Request a correction or removal.

Badge for the README

Maintain Upkie? Show its reproducibility score in the project's README. The badge links back to this page and updates with the score.

Badge: reproducibility 83/100

Markdown
[![Motari reproducibility score for Upkie](https://motari.io/api/v1/badge/upkie)](https://motari.io/r/upkie)
HTML
<a href="https://motari.io/r/upkie"><img src="https://motari.io/api/v1/badge/upkie" alt="Motari reproducibility score for Upkie" height="20"></a>

Not fully met yet: wiring diagram (partial). The score is read from the project's own sources, so publishing what is missing is what raises it. A score of 90 or more needs a reviewed build. How the score is computed