I2C IMU

The Perseus V2 system includes an I2C IMU (Inertial Measurement Unit) driver that provides orientation, angular velocity, and linear acceleration data through ROS2.

Supported IMU Types

The driver supports multiple IMU devices:

• LSM6DSOX (0x6A) - 6-axis accelerometer + gyroscope (default)
• MPU6050 (0x68) - 6-axis accelerometer + gyroscope
• MPU9250 (0x68) - 9-axis accelerometer + gyroscope + magnetometer
• LSM6DS3 (0x6A) - 6-axis accelerometer + gyroscope

Building and Running

Enter Development Environment

nix develop

Build the Package

colcon build --packages-select perseus_sensors

Source the Environment

source install/setup.bash

Launch the IMU Node

ros2 launch perseus_sensors i2c_imu.launch.py

Configuration

Using Different IMU Types

To use a different IMU type, modify the config file at src/perseus_sensors/i2c_imu_driver/config/i2c_imu_config.yaml

Example configuration for MPU6050:

i2c_imu:
  ros__parameters:
    device_type: "mpu6050"
    i2c_bus: "/dev/i2c-7"
    device_address: 104
    update_rate: 100.0
    frame_id: "imu_link"

Multiple IMUs

For multiple IMUs of the same type, use different I2C addresses:

# First IMU
i2c_imu_1:
  ros__parameters:
    device_type: "lsm6dsox"
    device_address: 106
    frame_id: "imu_1_link"

# Second IMU
i2c_imu_2:
  ros__parameters:
    device_type: "lsm6dsox"
    device_address: 107
    frame_id: "imu_2_link"

Troubleshooting

Common Issues

1. Permission denied on I2C bus: Ensure the user has access to the I2C device
2. Device not found: Check if the IMU is properly connected and the correct address is used
3. Wrong device type: Verify the device_type parameter matches your physical IMU

Verification

To verify the IMU is working correctly:

ros2 topic echo /imu/data

The node publishes sensor_msgs/Imu messages containing orientation, angular velocity, and linear acceleration data.