Sand Dunes Rover Project

Spring 2025 Arapahoe Community College Robotics Club - rover project

Overview

This project implements a rover system designed for sand dune environments. The system consists of:

1. An Arduino-controlled Rover with DC motors, servo steering, IMU sensors, and LIDAR
2. A Raspberry Pi Controller that interfaces with sensors and communicates with the Arduino

System Architecture

Rover Hardware

The rover consists of:

• Arduino controller with SoftPWM for motor control
• 2 DC motor channels for differential drive
• 2 Servo channels for wheel steering
• I2C bus for sensor communication

Sensor System

The sensor system includes:

• MPU6050 IMU (Accelerometer/Gyroscope) connected via I2C
• LIDAR sensor connected via serial port for distance measurement
• UART connection between Raspberry Pi and Arduino for commands

Features

• Movement Control: Forward, backward, left, right, stop, and active braking
• Precision Steering: Servo-controlled wheel direction with configurable angles
• IMU Data: Real-time acceleration and gyroscope data collection
• Motion Detection: Algorithms to detect significant movement changes
• LIDAR Scanning: Collects distance measurements across 360° rotation
• Data Processing: Converts LIDAR polar coordinates to Cartesian
• Data Logging: Records LIDAR measurements to timestamped files

Control System

Arduino Motor Control

• DC Motor States:

  • Forward: IN1=HIGH, IN2=LOW
  • Reverse: IN1=LOW, IN2=HIGH
  • Brake: IN1=HIGH, IN2=HIGH
  • Coast: IN1=LOW, IN2=LOW

• Servo Control:

  • Straight position: 45 degrees (configurable)
  • Turn margin: 45 degrees (configurable)

Command Interface

The rover accepts the following UART commands:

• f: Move forward
• b: Move backward
• l: Turn left
• r: Turn right
• s: Stop motors (coast)
• t: Brake motors (active stop)
• w: Start writing LIDAR data
• e: End writing LIDAR data
• q: Quit controller program

Sensor Details

MPU6050 IMU Sensor

• Measures acceleration and angular velocity in 3 axes
• Detects movement with configurable thresholds
• Provides data in physical units (g for acceleration, degrees/s for rotation)

LIDAR Sensor

• Rotational scanner providing 360° distance measurements
• Data provided in polar format (angle, distance, intensity)
• Converts to Cartesian coordinates (x, y)
• Outputs timestamped data for analysis and mapping

Data Format

IMU Data Format

Accel (g): X=0.00, Y=0.00, Z=0.00 | Gyro (deg/s): X=0.00, Y=0.00, Z=0.00

LIDAR Data Format

timestamp,angle,distance,intensity,x,y
1711212151.324,352.45,342,127,328.4,-95.2

Getting Started

Prerequisites

• Arduino with SoftPWM, Servo, and SoftI2CMaster libraries
• Raspberry Pi with Python 3
• Required Python packages:
  • serial
  • smbus
  • time
  • struct
  • math
  • os
  • datetime

Hardware Setup

1. Connect Arduino to Raspberry Pi via UART (/dev/ttyACM0)
2. Connect MPU6050 to I2C bus 1
3. Connect LIDAR to serial port (/dev/ttyUSB0)
4. Connect motors and servos as defined in the pin assignments

Running the Controller

1. Power on the rover hardware
2. Run the Python controller script
3. Enter commands via the terminal interface

Troubleshooting

IMU Issues

• Check I2C bus connections
• Verify the IMU address (default: 0x68)
• Use scan_bus() function to detect connected I2C devices

LIDAR Issues

• Verify serial port connection (/dev/ttyUSB0)
• Ensure baudrate is set to 230400
• Check data format with debug output

Motor Control Issues

• Verify the Arduino is properly responding to commands
• Check motor driver connections
• Verify servo positions and calibration