Marvin, a 3D-Printed Open-Source Robot (ESP32 + FreeRTOS)

Marvin is a fully 3D-printed open-source robot based on an ESP32 microcontroller running FreeRTOS. He features animated LCD eyes, an OLED mouth, servo-driven arm and head movements, stepper-based locomotion, sound sensing, orientation sensing, autonomous behaviors, and optional Wi-Fi remote control.

The project is designed for makers, students, and educators who want to explore embedded systems, electronics, the Arduino framework, 3D printing, PCB design, and robotics in a hands-on way. Marvin uses inexpensive and widely available components such as breakout boards, servos, steppers, and an ESP32 D1-mini module, making the robot reproducible without specialized tools.

All project files are publicly available, including firmware, PCB design files (KiCad), CAD models (Autodesk Fusion), STL and 3MF printing data, and a complete bill of materials.

🔧 GitHub Repository:
https://github.com/lhm0/marvin_robot

📄 Build Instructions (Instructables):
https://www.instructables.com/ESP32-B...

The robot can be built as a small “lively” desktop companion or as an educational platform for teaching robotics concepts such as real-time scheduling, I/O control, sensor fusion, and behavior control.

Technologies used:
– ESP32 (D1-mini module)
– FreeRTOS task scheduling
– Arduino framework (PlatformIO)
– KiCad for PCB design
– Autodesk Fusion for CAD
– 3D printing (STL + 3MF)
– Wi-Fi remote control
– Servo / stepper motor control
– I2S audio output + microphone input
– MPC6050 orientation sensing

If you decide to build your own version or modify the design, I’d be happy to see it!

00:00 Introduction
00:47 Project Goals
01:19 Actuators and Displays
02:54 The ESP32 and Electronics
03:30 The 3D-Printed Mechanical Enclosure
03:54 Behaviors: Eyes, Mouth, Sound
04:17 FreeRTOS Processes and Scheduling
05:00 Servo and Stepper Movements
05:44 Sound Detection
06:04 Orientation and Service Modes
06:53 Wi-Fi Remote Control
07:33 Resources for Reconstruction
07:44 GitHub Repository Overview
09:05 CAD and PCB Design Files
09:44 Software in VS Code (PlatformIO)
10:26 Instructables Build Guide
10:47 Concluding Remarks