driver_mpu9250

Overview

This package includes driver software for the InvenSense MPU9250 9DoF IMU. It provides a base driver class that allows a device specific (e.g. RPi, Arduino, etc.) driver to be easily derived and implemented. In it's current state, this repository includes a derived driver for the Raspberry Pi using pigpio.

Keywords: mpu9250 imu driver raspberry_pi

License

The source code is released under a MIT license.

Author: Paul D'Angio
Maintainer: Paul D'Angio, pcdangio@gmail.com

The driver_mpu9250 package has been tested under ROS Melodic and Ubuntu 18.04. This is research code, expect that it changes often and any fitness for a particular purpose is disclaimed.

Installation

Building from Source

Dependencies

• Robot Operating System (ROS) (middleware for robotics)
• sensor_msgs_ext (ROS extended sensor messages)
• pigpio (Raspberry PI I/O)

Building

To build from source, clone the latest version from this repository into your catkin workspace and compile the package using

# Switch to your catkin workspace directory.
cd catkin_workspace

# Clone the package into the workspace src directory.
git clone https://github.com/pcdangio/ros-driver_mpu9250.git src/driver_mpu9250

# Build the package.
catkin_make

Usage

Run any of the driver nodes with (where xxx is the driver type):

rosrun driver_mpu9250 driver_mpu9250_xxx

For example, to run the node using a driver for a Raspberry Pi:

# First, in a different terminal, start up the PiGPIO Daemon:
sudo pigpiod

# In a second terminal, start up the driver.
rosrun driver_mpu9250 driver_mpu9250_rpi

Creating Device Drivers

This package uses polymorphism with a base driver class to enable drivers to be built for a variety of hardware interfaces. To create your own device-specific driver:

• Create a new class for your device driver that extends the base driver class in src/driver.h
• In your derived driver class, implement the several pure abstract functions of the base driver class
• Create a new main.cpp that instantiates your derived class and passes it to the src/ros_node.h instance through polymorphism before running the node.
• Add the new main.cpp to your CMakeLists.txt as a new node executable.

You can refer to the following files in this package as an example for creating your custom device driver:

src/rpi_driver.h
src/rpi_driver.cpp
src/main_rpi.cpp
CMakeLists.txt

If you have created and tested a driver for a device not already covered in this package, please feel free to submit a pull request!

Nodes

rpi_node

A Raspberry Pi driver for MPU9250. Ensure that the pigpio daemon is running before starting this node, and that your username is added to the 'gpio' group.

Published Topics

• imu/accelerometer (sensor_msgs_ext/accelerometer) The acceleration measurements from the MPU9250.
• imu/gyroscope (sensor_msgs_ext/gyroscope) The gyroscope measurements from the MPU9250.
• imu/magnetometer (sensor_msgs_ext/magnetometer) The magnetic field measurements from the onboard AK8963 compass.
• imu/temperature (sensor_msgs_ext/temperature) The die temperature of the MPU9250 sensor.

Services

• imu/calibrate_gyroscope (driver_mpu9250_msgs/calibrate_gyroscope) Calibrates the gyroscope by calculating and removing gyroscope bias. The bias is calculated by averaging gyroscope data over an averaging period.

Parameters

• ~/i2c_bus (int, default: 1)
  The I2C bus to communicate with the MPU9250 over.

• ~/i2c_address (int, default: 0x68) The I2C address of the MPU9250.

• ~/interrupt_gpio_pin (int, default: 0)
  The GPIO input pin connected to the MPU9250's interrupt pin. NOTE: You must use GPIO numbers, not pin numbers.

• ~/gyro_dlpf_frequency (int, default: 0)
  An enum value representing the digital low pass filter (DLPF) cutoff frequency for the gyroscopes.
  NOTE: The publishing rate of Imu, MagneticField, and Temperature messages will be approximately 2.5x the gyro OR accel DLPF frequency (whichever is larger).
  Enumerated Values:
  250Hz = 0
  184Hz = 1
  92Hz = 2
  41Hz = 3
  20Hz = 4
  10Hz = 5
  5Hz = 6

• ~/accel_dlpf_frequency (int, default: 0)
  An enum value representing the digital low pass filter (DLPF) cutoff frequency for the accelerometers.
  NOTE: The publishing rate of Imu, MagneticField, and Temperature messages will be approximately 2.5x the gyro OR accel DLPF frequency (whichever is larger).
  Enumerated Values:
  460Hz = 0
  184Hz = 1
  92Hz = 2
  41Hz = 3
  20Hz = 4
  10Hz = 5
  5Hz = 6

• ~/gyro_fsr (int, default: 0)
  The full scale range (FSR) of the gyroscopes.
  Enumerated Values:
  +/- 250deg/sec = 0
  +/- 500deg/sec = 1
  +/- 1000deg/sec = 2
  +/- 2000deg/sec = 3

• ~/accel_fsr (int, default: 0)
  The full scale range (FSR) of the accelerometers.
  Enumerated Values:
  +/- 2g = 0
  +/- 4g = 1
  +/- 8g = 2
  +/- 16g = 3

• ~/max_data_rate (float, default: 8000)
  The maximum allowable sensor data rate, in Hz. Data rate is normally calculated as half of the accel/gyro DLPF frequency (nyquist criterion). This parameter allows maximum cap on the data rate, regardless of the DLPF frequency.

Bugs & Feature Requests

Please report bugs and request features using the Issue Tracker.