⚖️ PID Balancing Robot

Defy gravity with math. Dynamically balance a two-wheeled ESP32 robot using an MPU6050.

📋 Overview

An inverted pendulum is a classic control theory problem. By reading the precise tilt angle from an IMU and applying a calculated counter-force via the wheels, the robot can remain upright indefinitely.

What you'll learn: I2C IMU reading, complementary/Kalman filters to fuse accelerometer and gyroscope data, and advanced PID loop tuning.

Estimated time: 6-8 hours. Difficulty: ⭐⭐⭐⭐⭐ Expert.

🧩 Components Needed

Component	Specification	Qty	Notes
ESP32 Development Board	Fast processing	1	Needed for fast PID loops
MPU6050	6-DOF IMU	1	Accelerometer + Gyro
Stepper Motors	NEMA 17 or similar	2	For precise, immediate torque
A4988 Drivers	Stepper Driver	2
Chassis	Custom/3D Printed	1	Center of mass should be high

📖 Step-by-Step Tutorial

Mechanical Build

A high center of gravity actually makes balancing EASIER because it falls slower. Mount heavy components (like batteries) near the top.

Read the IMU

Raw accelerometer data is noisy; raw gyro data drifts over time. Use a Complementary Filter: angle = 0.98 * (angle + gyro * dt) + 0.02 * accel.

Fast PID Loop

The PID loop must run at a strict, fast interval (e.g., 200Hz). Use timer interrupts on the ESP32 to ensure the loop timing is precise.

Drive Steppers

Unlike DC motors, steppers need step pulses. The PID output determines the frequency of these step pulses (speed).

💡

Tuning a balancing robot PID: Set Kp until it oscillates quickly. Set Kd to slow down the oscillation. Set Ki to fix long-term drift.

💻 Code / Configuration

balancing_bot.ino

INO

// Balancing Robot IMU Filter (Snippet) - Volt X
#include <Wire.h>
#include <MPU6050.h>

MPU6050 mpu;
float angle, gyroRate;
unsigned long lastTime;

void setup() {
  Wire.begin();
  mpu.initialize();
  lastTime = micros();
}

void loop() {
  unsigned long now = micros();
  float dt = (now - lastTime) / 1000000.0;
  lastTime = now;
  
  int16_t ax, ay, az, gx, gy, gz;
  mpu.getMotion6(&ax, &ay, &az, &gx, &gy, &gz);
  
  // Calculate accelerometer angle
  float accelAngle = atan2(ay, az) * 180 / PI;

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