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
- WiFi-based control
- HTTP API for movement commands
- Live video streaming over WiFi
- Compatible controllers:
- Python desktop controller — displays the live video stream and sends gamepad-based control commands to the rover via HTTP.
- Android mobile app — displays the live video stream and 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-mini/3d-models/
The complete mechanical design is also available in STEP format: pathfinder-mini/cad/papaya-pathfinder-mini.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 differential bar for the rocker-bogie suspension |
differential_link.stl |
2 |
PETG / PLA |
Links between the differential bar and each suspension arm |
motor_retainer.stl |
6 |
PETG / PLA |
Holds each N20 motor |
rim.stl |
6 |
PETG / PLA |
Wheel rims |
tire.stl |
6 |
TPU |
Tires |
Wiring Diagram
- System Overview: High-level overview of the complete rover wiring, combining power,
motor drivers and control logic.
License
This project is licensed under the Apache License 2.0.
See the LICENSE file for details.
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