ESP32 Hexapod Robot Controller

This repository contains the firmware for an 18-DOF (Degree of Freedom) hexapod walking robot powered by the ESP32. It handles inverse kinematics, leg coordination, balance leveling, and multiple remote control interfaces in real-time.

There are two versions of this project available in this repository:

• main branch (This branch): The optimized classic Arduino version using a modular .ino structure.
• feature/freertos-native-architecture branch: A native FreeRTOS version structured into clean C++ header and source files (.h/.cpp) using advanced RTOS queues and event groups.

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Features

• Real-Time Inverse Kinematics (IK): Smooth analytical leg angle calculation running at 50Hz.
• Davenport Auto-Leveling: Dynamic body leveling using an MPU6050 IMU and PID correction.
• Smooth Gait Generation: Support for Tripod, Ripple, and Wave gaits using cycloid trajectories.
• Multiple Control Interfaces: Control the robot using a Web App (WebSockets), BLE, or an NRF24L01+ physical remote.
• Wireless Updates (OTA): Upload firmware upgrades wirelessly over WiFi.
• Safety Watchdog: Built-in hardware watchdog timer (TWDT) and battery protection to shut down servos if power gets too low.

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Kinematics & Coordinate System

Below is the layout of the leg coordinates, joint angles ($\alpha, \beta, \gamma$), and leg numbering configurations:

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Hardware Connection Diagram

Below is the wiring schematic showing the connection between the ESP32, PCA9685 servo drivers, MPU6050 sensor, and wireless modules:

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Project Structure

On this branch, the files inside the Hexapod Code folder use standard modular .ino structure:

• hexapod_esp32_v3.ino: Main setup, loop, global variables, and task registration.
• hexapod_tasks.ino: Core 0 (sensors/comm) and Core 1 (kinematics) task loops.
• hexapod_drivers.ino: PCA9685 I2C driver utilizing auto-increment write optimizations.
• hexapod_ik.ino & hexapod_gait.ino: Kinematics equations, cycloid step generation, and gait plans.
• hexapod_wifi.ino & hexapod_comm.ino: WiFi connection, WebSockets handling, BLE, and NRF24 receiver.
• hexapod_config.ino: Settings loading/saving from NVS protected by CRC32 check.
• hexapod_battery.ino & hexapod_watchdog.ino: Power tracking and TWDT system safety.
• hexapod_telemetry.ino: Real-time fast/slow telemetry serialization.

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Getting Started

Prerequisites

To compile the code, you will need the following libraries installed in your Arduino IDE:

• ArduinoJson (by Benoit Blanchon)
• WebSockets (by Markus Sattler)
• RF24 (by TMRh20 - optional, for physical remote control)

Uploading the Code

1. Open hexapod_esp32_v3.ino inside the Hexapod Code folder in Arduino IDE.
2. Under Tools, configure the ESP32 partition scheme to Minimal SPIFFS (1.9MB APP).
3. Select your ESP32 Dev Module port.
4. Click Upload.

Controlling the Robot

• On startup, the robot creates a WiFi Access Point named Hexapod-Setup (password: 12345678).
• Connect to it and open your WebSocket client (or custom controller) at ws://192.168.4.1:81.
• Send walking commands as JSON packets:

  {
    "cmd": "motion",
    "x": 50,
    "y": 0,
    "yaw": 10
  }

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License

Licensed under the MIT License. See LICENSE for details.

Developed & maintained by Ali Eren Safi.