Description

Papaya Pathfinder is an open-source family of small remote-controlled rovers based on the ESP32.

The project currently includes two rover variants, designed for different sizes, motors, and power requirements.

All mechanical parts of the rovers are fully 3D-printable,

The rovers can be operated using either WiFi or ExpressLRS (ELRS), depending on the firmware configuration.

Details

Papaya Pathfinder

Papaya Pathfinder is an open-source family of small remote-controlled rovers based on the ESP32.

The project currently includes two rover variants, designed for different sizes, motors, and power requirements.

All mechanical parts of the rovers are fully 3D-printable, and all models are available in the 3d-models/ directories of each rover variant.

The rovers can be operated using either WiFi or ExpressLRS (ELRS), depending on the firmware configuration.

Watch the Papaya Pathfinder demo on YouTube

Papaya Pathfinder

Controller: ESP32
Radio: ELRS receiver (required only when running firmware-elrs)
Motor Drivers: 2× BTS7960 43A (or similar high-current driver)
Motors: 6× GA25 DC gear motors
Steering: 4× MS24 servos
Power: LiPo 3S Battery
Voltage Regulation:
- 1× UBEC 5V/3A (for ESP32)
- 1× UBEC 6V/8A (High current supply for Servos)

Firmware

The rover supports multiple firmware configurations, each enabling a different communication method.

firmware-wifi
- WiFi-based control
- HTTP API for movement commands
- Compatible controllers:
  - Python desktop controller — sends gamepad-based control commands to the rover via HTTP.
  - Android mobile app — enables rover control using a gamepad, providing the same driving experience available on the desktop controller.
firmware-elrs
- Control via ExpressLRS (ELRS)

3D-Printed Parts

All STL files for this rover are available in: pathfinder/3d-models/

The complete mechanical design is also available in STEP format: pathfinder/cad/papaya-pathfinder.step

Use PETG or PLA for the structural parts, and TPU for the tires. All parts are designed to be assembled using M3 screws and nuts.

File	Qty	Material	Notes
`body.stl`	1	PETG / PLA	Main chassis
`arm_left.stl`	1	PETG / PLA	Left suspension arm
`arm_right.stl`	1	PETG / PLA	Right suspension arm
`pivot_left.stl`	1	PETG / PLA	Left pivot mount
`pivot_right.stl`	1	PETG / PLA	Right pivot mount
`differential_bar.stl`	1	PETG / PLA	Central rocker-bogie differential bar
`differential_link_left.stl`	1	PETG / PLA	Left link between differential bar and suspension arm
`differential_link_right.stl`	1	PETG / PLA	Right link between differential bar and suspension arm
`motor_mount.stl`	4	PETG / PLA	Motor mounts for GA25 motors used on steering arms
`horn_adapter.stl`	4	PETG / PLA	Servo horn adapters for steering servos. Print horizontally for strength.
`rim.stl`	6	PETG / PLA	Standard option. Connects directly to the motor shaft (D-shape). Simple, but can strip over time under high torque.
`rim_hexagonal.stl`	6	PETG / PLA	Pro option (Recommended). Requires 12mm brass hex adapters. Much stronger connection, prevents the motor shaft from stripping the plastic.
`tire.stl`	6	TPU	Tires

Wiring Diagram

Power Distribution: Shows the rover power distribution, including the LiPo 3S battery, separate UBECs for logic (5V) and servos (6V), and the motor power rails.
Motors: Motor wiring using two BTS7960 drivers, each controlling one side of the rover. The ESP32 provides PWM control signals to each driver.
Servos: Servo wiring powered by a dedicated 6V UBEC. PWM control signals are provided by the ESP32.
System Overview: High-level overview of the complete rover wiring, combining power, motor drivers, servos and control logic.

Papaya Pathfinder Mini

ESP32 with camera (ESP32-CAM / ESP32-S3-CAM) (required only when running firmware-wifi)
ELRS receiver (required only when running firmware-elrs)
6× N20 DC gear motors
Power supply: LiPo 2S
Voltage regulation:
- 1× DC-DC step-down to 5V (ESP32 / ESP32-CAM)
- 1× DC-DC step-down to 6V (N20 motors)

Firmware

The rover supports multiple firmware configurations, each enabling a different communication method.

firmware-wifi...

Discussions

Gio wrote 03/20/2026 at 14:59

Just starting the assembly, can you let me know what hardware you used to join everything? jut bolts and nuts, or something else?

Are you sure? yes | no

Sergio García Sánchez wrote 03/21/2026 at 14:27

Only standard M3 bolts and nuts are needed to assemble everything. If you are using the rim_hexagonal.stl wheels, you will also need 12 mm brass hex adapters from RC wheels

Are you sure? yes | no

steve wrote 03/03/2026 at 20:47

Thanks for your suggestions - I tried the above but I think maybe the tire had just shrunk too much as there was a long delay after I printed it before I tried fitting the wheels. I tried warming the tire & cooling the wheels, all kinds of things, but no luck there.
What I finally did was a 'hack' solution, but it worked... I have a 54mm hole saw (2-1/8") and I put that on my drill press and carefully bored out the inside of the tire. It was a bit rough but I think with some epoxy and glue it will be fine. If I reprint the wheels I'll make the wall thicknesses much higher to allow room for the saw. Worst case it looks like a standard RC 'offroad' Truck tire might also fit well out of the box, and they are not too expensive.
This is part of the fun of building a custom project -- I appreciate the collaboration! I'll upload pics with my build and a detailed BOM to supplement yours as well. I do intend to build mine out with a sensor mast (ultrasonic & camera) eventually! Love the project. Great design and a lot to build from. Thanks, sir!

Are you sure? yes | no

Gio wrote 02/21/2026 at 09:53

Is the android app a work in progress? gets a 404 error when I click the link. This is going to be a fun project.

Are you sure? yes | no

Sergio García Sánchez wrote 02/23/2026 at 00:26

I’ve fixed the project links.

To use the Android app, you need a controller. Any controller compatible with Xbox, PlayStation or PC should work

Are you sure? yes | no

steve wrote 02/15/2026 at 16:57

I'm excited by this project and am working on assembly. I am having difficulty on the full-size rover getting the wheels inside the tires. Do you have a recommendation on how best to fit the wheels to the tires? I know we need a very snug fit but I'm having no luck stretching the tires, etc. to allow the wheels to fit.

Are you sure? yes | no

Sergio García Sánchez wrote 02/23/2026 at 00:26

’m really happy to see someone building it!

This is honestly one of the most difficult parts of the whole assembly. Unfortunately, I don’t have a perfect solution. I managed to do it mostly with patience.

What worked for me was:

- Insert one section of the wheel rim into the tire first.

- Place that part on a flat surface.

- Then, using both hands, press the tire downward while pushing the wheel in gradually around the perimeter.

It takes some force, but doing it progressively instead of trying to snap it in at once helps a lot.

If it’s still too difficult, you could slightly modify the design, for example, increase the wheel diameter by about 1 mm and then secure it with adhesive. That can make assembly much easier while still keeping a firm fit.

Are you sure? yes | no

Papaya Pathfinder: Open Source ESP32 Rover

Description

Details

Papaya Pathfinder

Papaya Pathfinder

Firmware

3D-Printed Parts

Wiring Diagram

Papaya Pathfinder Mini

Firmware

Discussions

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Papaya Pathfinder: Open Source ESP32 Rover

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Description

Details

Papaya Pathfinder

Papaya Pathfinder

Firmware

3D-Printed Parts

Wiring Diagram

Papaya Pathfinder Mini

Firmware

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