OmniDrone Flight Control System

A sophisticated flight control system for an omni-directional drone using ESP32 microcontroller, featuring advanced stabilization, altitude hold, and safety features.

Hardware Components

Core Components

• Flight Controller: ESP32 Development Board
• IMU: MPU6050 (Gyroscope + Accelerometer)
• Radio: NRF24L01 2.4GHz Transceiver
• Altitude Sensor: LightWare LW20/C LIDAR
• Battery Monitor: MAX17043 Fuel Gauge
• Motors: 4x Brushless DC Motors
• ESCs: 4x DShot600-compatible Electronic Speed Controllers (ESCs)

ESC Protocol

This project currently only supports DShot600 protocol for ESC communication. The implementation uses the ESP32's RMT (Remote Control) peripheral for precise timing control, based on the excellent DShotRMT library by derdoktor667.

DShot600 Specifications:

• Bitrate: 600kbit/s
• Bit timing: 1.67µs per bit
• Frame time: 26.72µs
• Signal timing:
  • Bit 1: 1.25µs high, 0.625µs low
  • Bit 0: 0.625µs high, 1.25µs low

ESP32 Connections

Component	ESP32 Pin	Description
MPU6050
SDA	GPIO 21	I²C Data
SCL	GPIO 22	I²C Clock
VCC	3.3V	Power
GND	GND	Ground
NRF24L01
CE	GPIO 4	Chip Enable
CSN	GPIO 5	Chip Select
MOSI	GPIO 23	SPI MOSI
MISO	GPIO 19	SPI MISO
SCK	GPIO 18	SPI Clock
VCC	3.3V	Power
GND	GND	Ground
LightWare LW20/C
TX	GPIO 16	UART RX
RX	GPIO 17	UART TX
VCC	5V	Power
GND	GND	Ground
MAX17043
SDA	GPIO 21	I²C Data
SCL	GPIO 22	I²C Clock
VCC	3.3V	Power
GND	GND	Ground
ESCs
Motor1	GPIO 25	Front Right Motor
Motor2	GPIO 26	Front Left Motor
Motor3	GPIO 27	Rear Left Motor
Motor4	GPIO 33	Rear Right Motor

Quick Start Guide for Beginners

Testing Motors with Arduino IDE

Before diving into the full flight control system, you can test your hardware setup using our simple motor test sketch.

1. Hardware Setup

   • Connect your ESP32 to your computer
   • Wire the ESCs to the following pins:
     • Motor1 (Front Right): GPIO 25
     • Motor2 (Front Left): GPIO 26
     • Motor3 (Rear Left): GPIO 27
     • Motor4 (Rear Right): GPIO 33
   • Connect ESC power to a suitable battery/power supply

2. Software Setup

   • Install Arduino IDE
   • Install ESP32 board support
   • Download and install the DShotRMT library
   • Open tutorial/DShot_Motor_Test.ino

3. Testing Procedure

   • Upload the sketch to your ESP32
   • Open Serial Monitor (115200 baud)
   • Use the following commands:
     • motor,speed (e.g., "1,50" sets motor 1 to 50% speed)
     • 0,0 stops all motors
   • Test each motor individually to verify:
     • Proper connections
     • Correct rotation direction
     • Smooth throttle response

4. Safety Notes

   • Remove propellers during initial testing
   • Keep fingers away from motors
   • Have a way to quickly disconnect power
   • Start with low throttle values (10-20%)

This test provides a simple way to verify your hardware setup before proceeding with the full flight control implementation.

Software Architecture

Core Systems

1. Flight Control

   • PID controllers for roll, pitch, yaw, and altitude
   • Multiple flight modes including manual and altitude hold
   • Safety features and failsafe mechanisms

2. Sensor Integration

   • MPU6050 for attitude estimation
   • LightWare LW20/C for precise altitude measurements (0.2-50m range)
   • MAX17043 for battery monitoring

3. Communication

   • Bidirectional telemetry
   • Control input processing
   • Fail-safe communication monitoring

Flight Modes

1. Normal Operation

   • Full manual control
   • Real-time attitude stabilization

2. Altitude Hold

   • Maintains specified altitude using LIDAR
   • Allows focus on horizontal movement

3. Safety Modes

   • Warning Low Battery: Limited performance
   • Return to Home: Automated return (requires GPS, not implemented)
   • Emergency Landing: Controlled descent
   • Failsafe: Emergency motor stop

Building and Flashing

1. Prerequisites

   # Required libraries
   - ESP32Servo
   - MPU6050
   - RF24
   - LightWare_LW20
   - MAX17043

2. Build Process

   mkdir build
   cd build
   cmake ..
   make

3. Flashing

   # Using esptool
   esptool.py --port /dev/ttyUSB0 write_flash 0x10000 OmniDrone.bin

Safety Features

1. Battery Management

   • Real-time voltage monitoring
   • Multiple warning thresholds
   • Automatic landing on critical battery

2. Motor Safety

   • Gradual throttle changes
   • Emergency stop capability
   • Motor failure detection

3. Communication Safety

   • Signal loss detection
   • Automatic failsafe activation
   • Telemetry monitoring

Calibration and Setup

1. ESC Calibration

   • Power on with zero throttle
   • Wait for ESC initialization beeps
   • System automatically sets proper PWM range

2. Sensor Calibration

   • MPU6050 auto-calibrates on startup
   • Place drone on level surface during boot
   • Allow 5 seconds for gyro calibration

3. Radio Setup

   • Verify NRF24L01 addresses match between transmitter and receiver
   • Test range before flight
   • Verify failsafe behavior

Operation Guidelines

1. Pre-flight Checks

   • Battery voltage above 30%
   • All sensors reporting valid data
   • Motors responding to input
   • Radio link established

2. Flight Controls

   • Throttle: Vertical movement
   • Roll: Left/Right tilt
   • Pitch: Forward/Backward tilt
   • Yaw: Rotation
   • Altitude Hold: Automatic height maintenance

3. Emergency Procedures

   • Low battery: Land immediately
   • Signal loss: Automatic landing
   • Sensor failure: Switch to manual mode
   • Critical failure: Emergency stop

Troubleshooting

Common issues and solutions:

1. Unstable Flight

   • Check PID tuning parameters
   • Verify sensor readings
   • Check propeller balance

2. Communication Issues

   • Verify NRF24L01 connections
   • Check radio channel settings
   • Verify antenna orientation

3. Sensor Errors

   • Check I²C connections
   • Verify power supply stability
   • Check for interference sources

Contributing

Feel free to contribute to this project by:

1. Reporting issues
2. Suggesting enhancements
3. Creating pull requests

License

This project is licensed under the MIT License - see the LICENSE file for details.

Acknowledgments

Special thanks to:

• derdoktor667 for the DShotRMT library, which provides the foundation for our ESC communication implementation
• The ESP32 community for their extensive documentation and support

Altitude Sensing

The LightWare LW20/C LIDAR provides:

• Range: 0.2m to 50m
• Update Rate: up to 388 readings per second
• Accuracy: ±0.1m
• Serial Interface: 3.3V TTL UART
• Supply Voltage: 5V DC
• Low power consumption: 100mA (typical)