ESP32 Firmware

This page documents the ESP32-based firmware for the Weefee quadruped robot.

Architecture Overview

The ESP32 firmware uses ESP-IDF (Espressif IoT Development Framework) and micro-ROS to control the quadruped robot hardware. The firmware is organized into several key components:

espidf/weefee_esp32/
├── main/
│   ├── main.c                 # Main application with micro-ROS integration
│   ├── quadruped_kinematics.h # Kinematics declarations
│   ├── quadruped_kinematics.c # Kinematics implementation
│   ├── quadruped_robot.h      # Robot control declarations
│   ├── quadruped_robot.c      # Robot control implementation
│   ├── servo_controller.h     # Servo control declarations
│   └── servo_controller.c     # Servo control implementation
└── components/
    └── micro_ros_espidf_component/ # micro-ROS integration

Main Components

1. Servo Controller

The servo_controller.h/c files handle the low-level control of the servomotors. Key features:

• PWM signal generation using ESP32's LEDC peripheral
• Calibration and angle mapping
• Safety limits to prevent servo damage

Key functions:

• setup_servos() - Initialize all servos with default positions
• set_servo_values() - Update servo angle values
• apply_servo_positions() - Apply angles to physical servos

2. Quadruped Kinematics

The quadruped_kinematics.h/c files implement forward and inverse kinematics algorithms. These mathematical functions convert between:

• Joint angles (servo positions)
• Foot positions in 3D space

Key functions:

• inverse_kinematics() - Calculate joint angles from a desired foot position
• forward_kinematics() - Calculate foot position from joint angles
• set_robot_dimensions() - Configure the robot's physical dimensions

3. Quadruped Robot

The quadruped_robot.h/c files provide high-level robot control. This includes:

• Gaits (walking, trotting)
• Body position and orientation control
• Leg coordination

Key functions:

• robot_init() - Initialize the robot
• robot_stand() - Put the robot in standing position
• robot_sit() - Put the robot in sitting position
• robot_start_gait() - Begin a walking pattern
• robot_stop_gait() - Stop any active movement
• robot_set_body_position() - Adjust the body position
• robot_set_body_orientation() - Adjust the body orientation

4. Main Application

The main.c file is the entry point that integrates all components:

• Initializes the ESP32 hardware
• Sets up micro-ROS communication
• Processes commands from ROS2
• Controls the robot based on commands

The firmware uses micro-ROS to communicate with ROS2 over WiFi or Ethernet.

Command Processing

The firmware uses a string-based command protocol. When commands are received via micro-ROS, they are parsed in the command_callback() function:

Command Type	Format	Example	Description
Servo	servo:angle1,angle2,...,angle12	servo:90,45,120,90,90,90,90,90,90,90,90,90	Direct servo control
Stand	stand	stand	Put robot in standing position
Sit	sit	sit	Put robot in sitting position
Walk	walk [speed]	walk 1.0	Start walking gait
Trot	trot	trot	Start trotting gait
Stop	stop	stop	Stop movement
Position	position x y z	position 0 0 20	Set body position
Orientation	orientation roll pitch yaw	orientation 0 10 0	Set body orientation

Communication

The robot communicates using micro-ROS with the following topics:

Topic	Type	Direction	Description
/robot_command	std_msgs/String	Input	Commands to control the robot
/robot_status	std_msgs/String	Output	Status messages from the robot
/robot_pose	geometry_msgs/Pose	Input	Body position and orientation

Configuration

The ESP32 firmware can be configured using idf.py menuconfig. Important configuration options:

• WiFi credentials
• micro-ROS agent IP and port
• Servo pin assignments
• Robot dimensions

Building and Flashing

cd espidf/weefee_esp32
idf.py build
idf.py -p /dev/ttyUSB0 flash

Logs and Debugging

The firmware uses ESP-IDF's logging system. You can view logs with:

idf.py -p /dev/ttyUSB0 monitor

Log levels can be adjusted in menuconfig under "Component config" → "Log output".