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Building a Robot Actuator with ESP32 and a 5010 BLDC Motor






Introduction

Modern robotics demands actuators that aren’t just strong, but also smart — capable of precise control, smooth motion, and safe human interaction. Traditional servos are great for small robots, but they can be stiff, noisy, and limited in range or torque.

This project demonstrates a custom robot actuator built around a 5010 360 KV brushless DC (BLDC) motor, controlled by an ESP32 running the SimpleFOC library. The goal is to create a compliant joint — one that can be moved by hand, but automatically returns to its home position with adaptive stiffness.

🧠 What Makes This Actuator Special

Unlike a typical servo, this actuator behaves intelligently:

  • You can turn it by hand — it feels soft and back-drivable.

  • When you release it, the motor returns to its initial position smoothly.

  • If you twist it harder (e.g., due to gear reduction), it becomes stiffer, resisting displacement more strongly.

  • It’s powered by 12 V and controlled by a simple ESP32 board using FOC (Field Oriented Control) for quiet, precise torque control.

⚙️ Hardware Overview

ComponentDescription
Motor5010 360 KV BLDC (12 N14 P)
Driver3-PWM MOSFET driver (e.g., L6234, DRV8313, or custom)
MicrocontrollerESP32 DevKit
Position SensorAS5600 I²C magnetic encoder
Power Supply12 V DC
FirmwareSimpleFOC running on Arduino framework

The AS5600 provides high-resolution angle feedback, while the ESP32 handles the FOC algorithm at high speed. The 5010 motor, commonly used in drones, provides excellent torque-to-weight ratio when combined with a gear reduction.

🔩 How It Works

The actuator uses a Field-Oriented Control (FOC) loop to control torque and position precisely.
At the core lies a compliance control strategy implemented in firmware:

  1. When the user moves the shaft by hand, the software detects a manual deviation.

  2. It reduces stiffness and limits voltage, allowing free motion.

  3. Once the movement stops, it gradually restores holding torque and returns the actuator to its home position.

This results in a natural, spring-like behavior — soft when you move it, firm when it holds position.

🧰 Firmware Logic Highlights

The core of the firmware is written using SimpleFOC and a few key logic blocks:

  • Angle control loop: Keeps the motor aligned with a target position.

  • Manual detection: Monitors angle deviation and angular velocity to detect hand movement.

  • Adaptive stiffness: Dynamically adjusts P_angle.P and voltage_limit to soften or stiffen response.

  • Return to home: When released, the motor returns smoothly to the original angle.

Here’s a simplified version of the control logic:

if (abs_err > manual_threshold) {
    // User is moving the actuator
    manual_mode = true;
    motor.P_angle.P = soft_P;
    driver.voltage_limit = free_voltage_limit;
} else if (manual_mode && velocity_is_low) {
    // User released it
    manual_mode = false;
    motor.P_angle.P = hold_P;
    driver.voltage_limit = hold_voltage_limit;
    target_angle = home_angle; // return to home
}

This logic makes the motor behave like a robotic spring joint — a balance between freedom and control.

🧩 Gearing and Stiffness

Because the 5010 motor is geared, torque at the output is multiplied, but so is resistance to back-driving.
To compensate, the firmware uses adaptive stiffness control — if you push harder (moving past the manual_threshold), the motor briefly increases its proportional gain (P_angle.P) and voltage limit to push back more strongly, ensuring a natural feel and stable return to the target.

You can tune this behavior with:

const float soft_P = 0.05f;   // free movement
const float hold_P = 1.0f;    // firm hold
const float free_voltage_limit = 1.0f;
const float hold_voltage_limit = 4.0f;

🔌 Power and Performance

At 12 V and around 1 A of current draw during active correction, the actuator is both efficient and quiet.
The ESP32’s dual cores easily handle the FOC loop and serial monitoring, leaving room for Wi-Fi, Bluetooth, or ROS2 communication in future updates.

🤖 Applications

  • Robotic arms and grippers with human-safe compliance

  • Exoskeleton joints with soft-touch feedback

  • Animatronics and camera gimbals requiring natural motion

  • Educational robotics — understanding FOC and compliant actuation


Conclusion

This ESP32-based 5010 actuator shows that compliance and precision don’t require expensive industrial hardware.
With open-source tools like SimpleFOC and affordable drone motors, you can build a smart, smooth, and safe robot joint for your next project.

Whether you’re a maker, researcher, or roboticist — this actuator is a great starting point for exploring modern, FOC-based compliant control.



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