imu_vn_100

The imu_vn_100 package is a linux ROS driver for VN-100 Rugged IMU of VECTORNAV. The package is developed based on the official SDK v0.3.2 for Linux. The user manual for the device can be found here.

The package is tested on Ubuntu 14.04 with ROS indigo.

Note that the official SDK is modified within this package due to some bugs or unsupported features. Please carefully update the SDK, since the new SDK may not work with the provided software.

License

• The license for the official SDK is the MIT license which is included in the include/imu_vn_100/vncpplib
• The license for the other codes is Apache 2.0 whenever not specified.

Compiling

This is a Catkin package. Make sure the package is on ROS_PACKAGE_PATH after cloning the package to your workspace. And the normal procedure for compiling a catkin package will work.

cd your_work_space
catkin_make --pkg imu_vn_100 --cmake-args -DCMAKE_BUILD_TYPE=Release

Example Usage

Parameters

port (string, default: \tty\USB0)

Port which the device connected to. This can be checked by command dmesg.

frame_id (string, default: imu)

The frame ID entry for the sent messages.

baudrate (int, 921600)

The baud rate of the serial port. The available baud rates can be checked on the user manual. It is suggested that the baud rate is kept at 921600 to ensure the high frequency transmission. The device will send permission denied error code if the baud rate cannot support the desired data package at the desired frequency.

imu_rate (int, 200)

The rate of the IMU data.

enable_magn  (bool, default: true)
enable_press (bool, default: true)
enable_temp  (bool, default: true)
enable_rpy  (bool, default: false)

Enable other possible messages that the driver is available to send. Note that the frequency of the data for each of these messages will be the same with the IMU data, if the topic is enabled.

sync_rate (int, 20)

The rate of the sync out trigger signal. Note that the actual rate may not exactly match the provided rate, unless the provided rate is a divisor of 800. When sync_rate <= 0, it is disabled.

binary_output (boolean, default: true)

Use binary protocol for receiving messages instead of ASCII.

binary_async_mode (int, default: 2)

Set serial port for binary messages to one of:

• 1 - Serial port 1
• 2 - Serial port 2

imu_compensated (boolean, default: true)

Use compensated IMU measurements (i.e. angular velocity, linear acceleration, magnetic field).

vpe_enable (boolean, default: true)

Use Vector Processing Engine.

vpe_heading_mode (int, default: 1)

Set VPE heading mode to one of:

• 0 - Absolute
• 1 - Relative
• 2 - Indoor

vpe_filtering_mode (int, default: 1)

Set VPE filtering mode to one of:

• 0 - Off
• 1 - MODE 1

vpe_tuning_mode (int, default: 1)

Set VPE tuning mode to one of:

• 0 - Off
• 1 - MODE 1

Published Topics

imu/imu (sensor_msgs/Imu)

If imu_compensated is false, the default, then the message contains the uncompensated (for the definition of UNCOMPENSATED, please refer to the user manual) angular velocity and linear acceleration. Otherwise both are compensated.

imu/magnetic_field (sensor_msgs/MagneticField)

Magnetic field. If imu_compensated is false then it is uncompensated otherwise it is compensated.

imu/pressure (sensor_msgs/FluidPressure)

Pressure.

imu/temperature (sensor_msgs/Temperature)

Temperature in degree Celsius

imu/rpy (geometry_msgs/Vector3Stamped)

Estimated roll (x), pitch (y) and yaw (z) angles in radians given as a 3,2,1 Euler angle rotation sequence describing the orientation of the sensor with respect to the inertial North East Down (NED) frame.

Node

With the provided launch file, do

roslaunch imu_vn_100 vn_100_cont.launch

FAQ

1. The driver can't open my device?
   Make sure you have ownership of the device in /dev.

2. Why I have permission error during the initialization process of the driver?
   Most often, this is because the baud rate you set does not match the package size to be received. Try increase the baud rate.

3. Why is the IMU data output rate much lower than what is set?
   This may be due to a recent change in the FTDI USB-Serial driver in the Linux kernel, the following shell script might help:

   # Reduce latency in the FTDI serial-USB kernel driver to 1ms
   # This is required due to https://github.com/torvalds/linux/commit/c6dce262
   for file in $(ls /sys/bus/usb-serial/devices/); do
     value=`cat /sys/bus/usb-serial/devices/$file/latency_timer`
     if [ $value -gt 1 ]; then
       echo "Setting low_latency mode for $file"
       sudo sh -c "echo 1 > /sys/bus/usb-serial/devices/$file/latency_timer"
     fi
   done

Bugs or Features Required of the Official SDK

• [Solved] Define macros for options to set synchronization register and communication control register. (vndevice.h)

• [Solved] Pressure entry is not properly parsed and overwrites temperature in vndevice_processAsyncData when the async data output type is set to VNASYNC_VNIMU. (vndevice.c)

• [Solved] Synchronization time or count is not parsed in vndevice_processAsyncData. (vndevice.c)

• Angular velocity and linear acceleration are flipped when the device is set to binary output using BG1_IMU

• Orientation and uncompensated IMU measurements cannot be acquired within a single setting using async output.