Auto-assembled, not yet reviewed

OpenBot

~$50 smartphone-brained wheeled robot for AI driving.

Reproducibility80/100Strong source coverage, unverifiedCADBOMWIREFWBUILDLICREPHow it is computed
OpenBot open-source 4-DoF mobile robot, 3D render from main_frame.stl
simplified 3D · main_frame.stl

About OpenBot

OpenBot turns an Android smartphone into the brain of a low-cost wheeled robot. The project provides 3D-printable body variants, Arduino Nano firmware, Android apps, controller tooling and a training pipeline so a small vehicle can do person following and real-time autonomous navigation. The upstream DIY bill of materials comes to about $50. No assembled CAD model of the robot is published.

Licenses

Hardware
MIT
Software
MIT
Docs
Not published

Degrees of freedom

4 DoF wheels 4

Breakdown source

Wheeledsource

How to build OpenBot

5 steps

Steps marked Motari summary condense the linked source; follow the source for exact instructions.

  1. Print the body

    Print a documented body variant such as the regular body top/bottom, plus the two phone mount parts from the STEP/STL files.

    Motari summarygithub.com/ob-f/OpenBot/blob/master/body/diy/README.md

  2. Assemble the chassis

    Mount the four TT motors and wheels, phone mount, battery holder and required fasteners into the printed body.

    Motari summarygithub.com/ob-f/OpenBot/blob/master/body/diy/README.md

  3. Wire the electronics

    Wire the motors to the L298N driver and Arduino Nano, add the 18650 battery pack and Dupont wiring, following the DIY wiring guide.

    Motari summarygithub.com/ob-f/OpenBot/blob/master/body/diy/README.md

  4. Flash the firmware

    Upload the OpenBot Arduino firmware to the Nano and connect it to the Android phone with the USB OTG cable.

    Motari summarygithub.com/ob-f/OpenBot/blob/master/body/diy/README.md

  5. Install the app and drive

    Install the Android OpenBot app, pair a controller, then run person-following or train a driving policy.

    Motari summarygithub.com/ob-f/OpenBot/blob/master/body/diy/README.md
Print timenot published
Assembly timenot published

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

OpenBot bill of materials

13 rows

Cost to build

$50USDsource total

In the source currency, as read on 2026-09-30. Not converted, and not checked against current vendor prices: none of these is a Motari-verified checkout total.

OpenBot parts, as the source lists them. Prices are the source's, not checked against vendors.

OpenBot bill of materials
PartQtySpecSourceConfidence
Arduino Nanomicrocontroller for DIY option
1ATmega328P Nano-class board
retailers linked by the projectprice not listedbody/diy/README.md line 76 lists 1x Arduino Nano with EU/US/AE retailer links
high
TT motors with tiresfour-wheel drive hobby motors
4yellow TT gearmotor with tire
retailers linked by the projectprice not listedbody/diy/README.md line 77 lists 4x TT motors with tires with EU/US/AE retailer links
high
18650 Li-ion batteriesvehicle battery cells
318650 cells
retailers linked by the projectprice not listedbody/diy/README.md line 78 lists 3x 18650 battery with retailer links
high
18650 battery holderthree-cell holder
13x 18650 holder
retailers linked by the projectprice not listedbody/diy/README.md line 79 lists 1x 18650 battery holder with retailer links
high
USB OTG cablephone-to-Arduino link
1USB OTG cable
retailers linked by the projectprice not listedbody/diy/README.md line 80 lists 1x USB OTG cable with retailer links
high
Spring or rubber bandphone mount retention
1spring or rubber band
retailers linked by the projectprice not listedbody/diy/README.md line 81 lists 1x spring or rubber band with retailer links
high
M3x25 screwsmotor/body/phone mount fasteners
16M3 x 25 mm screw
retailers linked by the projectprice not listedbody/diy/README.md line 82 lists 16x M3x25 screw with retailer links
high
M3 nutsmatching fasteners
16M3 nut
retailers linked by the projectprice not listedbody/diy/README.md line 83 lists 16x M3 nut with retailer links
high
M3x5 screwselectronics/sensor mounting fasteners
6M3 x 5 mm screw
retailers linked by the projectprice not listedbody/diy/README.md line 84 lists 6x M3x5 screw with retailer links
high
Dupont cablesDIY wiring harness
1jumper wire set
retailers linked by the projectprice not listedbody/diy/README.md line 85 lists Dupont cables with retailer links
high
L298N motor driverDIY option dual H-bridge driver
1L298N motor driver module
retailers linked by the projectprice not listedbody/diy/README.md line 97 lists 1x L298N Motor Driver for DIY option with retailer links
high
3D-printed regular body and phone mountstandard DIY body: body top/bottom plus two phone mount parts
1STEP/STL printable parts
3D print yourselffilament not costedbody/diy/README.md lines 24 and 31-34 identify regular body option and phone mount STEP/STL parts
high
Android smartphonerobot brain; usually reused
1Android phone with camera and sensors
reusenot included in about-$50 body claimREADME.md line 27 says OpenBot uses Android smartphones as brains for low-cost robots
high

Rows from the source's own parts list 15

README.md@abac28bmarkdown

Source rowQtyPrice and vendorLine
about $50 Android smartphone robot body
source-linked retailersno price listed
L27

body/diy/README.md@abac28bmarkdown

Source rowQtyPrice and vendorLine
regular body printable body option
source-linked retailersno price listed
L24
phone_mount_bottom STEP/STL
1x
source-linked retailersno price listed
L33
phone_mount_top STEP/STL
1x
source-linked retailersno price listed
L34
Arduino Nano
1x
EUUSno price listed
L76
TT motors with tires
4x
EUUSno price listed
L77
18650 battery
3x
EUUSno price listed
L78
18650 battery holder
1x
EUUSno price listed
L79
USB OTG cable
1x
EUUSno price listed
L80

6 more rows in body/diy/README.md

OpenBot source files

14 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.

OpenBot in simulation

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

No URDF, MJCF, SDF, USD or Onshape model has been found in the sources.

The 3D specimen on this page is converted from body/rc_truck/cad/rc_truck_body/main_frame.stl at abac28b.

Builds of OpenBot

0 reviewed

No reviewed builds of OpenBot 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 ob-f/OpenBot: 2026-09-25 (checked 2026-10-01)

Related links

How this page was made

Assembled from public sources on 2026-06-04, 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: source-linked DIY BOM; prices not vendor-reconciled.

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

Badge: reproducibility 80/100

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

Not fully met yet: bom evidence (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