Papaya Pathfinder

Papaya Pathfinder patch

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 - Demo Video

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

Printables

Papaya Pathfinder model

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.
    Papaya Pathfinder power distribution
  • Motors: Motor wiring using two BTS7960 drivers, each controlling one side of the rover. The ESP32 provides PWM control signals to each driver.
    Papaya Pathfinder motors
  • Servos: Servo wiring powered by a dedicated 6V UBEC. PWM control signals are provided by the ESP32.
    Papaya Pathfinder servos
  • System Overview: High-level overview of the complete rover wiring, combining power, motor drivers, servos and control logic.
    Papaya Pathfinder overview

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.

Read more »