vectornav_driver

A minimal driver for VectorNav IMUs

Setup

Setup dependancies

sudo apt-get install libspdlog-dev

Setup build

mkdir -p catkin_ws/src
cd catkin_ws/src
git clone [email protected]:ntnu-arl/vectornav.git
cd ..
catkin config -DCMAKE_BUILD_TYPE=Release
catkin build

Usage

Usage of the VN100 via a USB connection requires an FTDI TTL converter. The converter should be connected to the VN100 as shown below

Pin Number on VN100	Label on VN100	Label on FTDI TTL Converter
1	VCC	VCC
5	GND	GND
8	TX2_TTL	RX
9	RX2_TTL	TX

The complete pin assignments for the VN100 can be found in the user manual

Note that the default output from the VN100 is in the NED coordinate system.

Note that the filter topics are bias compensated (with the onboard filter) whereas the imu topics are not.

Topic	Message Type	Description
imu/data	sensor_msgs/Imu	Raw IMU data
imu/mag	sensor_msgs/MagneticField	Raw magnetometer data
filter/data	sensor_msgs/Imu	IMU data from the onboard filter
filter/mag	sensor_msgs/MagneticField	Magnetometer data from the onboard filter
temperature	sensor_msgs/Temperature	Temperature of the IMU
pressure	sensor_msgs/FluidPressure	Pressure measured by the IMU
sync_out_stamp	std_msgs/Header	Approximate timestamp of the sync_out signal

Service Name	Service Type	Description
reset	std_srvs/Empty	Resets the IMU

Setting up custom udev rules

1. Use udevadm info --attribute-walk /dev/ttyUSB0 (change /dev/ttyUSB0 to the port that the converter is connected to) to find the values for your FTDI converter. Typically, idProduct, idVendor and serial should be enough.

2. Edit the vectornav_driver/udev/99-vn100.rules file and replace the values with the ones from your converter.

3. Edit the SYMLINK line in the vectornav_driver/udev/99-vn100.rules file and replace the value with the name of the device that you want to use.

4. Copy the vectornav_driver/udev/99-vn100.rules file to /etc/udev/rules.d/.

   cd catkin_ws/src
   sudo cp vectornav/vectornav_driver/udev/* /etc/udev/rules.d/
   sudo udevadm control --reload-rules && udevadm trigger

5. Add your user to the dialout group with sudo usermod -a -G dialout $USER.

6. Restart the computer.

Note:

1. The USB latency timer should be set to 1 for the IMU to avoid the bunching up of IMU messages. The udev rule automatically does this for you.
2. You can use udevadm test $(udevadm info --query=path --name=/dev/ttyUSB0) to test whether the new rule works as expected. If the rule works, it should show you the attributes for the converter with the rule that was triggered.
3. You may need to unplug and replug the IMU to make the udev rule take effect.
4. If the udev rules do not load, you may need to restart the computer. This only needs to be done once during the setup.

Setting up the parameters

Modify the vectornav_driver/config/vn100_params.yaml per your requirements.

Running the node

cd catkin_ws
source devel/setup.bash
roslaunch vectornav_driver vectornav_driver.launch

Compatibility

This driver has been tested on the following systems:

• VN100 Rugged - USB:
  • Pop OS 20.04 x86-64
  • Ubuntu 20.04 arm64
  • Ubuntu 20.04 x86-64

Known Issues

The Seeed Studio A603 carrier board for the NVIDIA Orin NX has an issue with the kernel drivers for usbserial. Essentially, instead of using the usbserial.ko for the board which are modified by Seeed, the default usbserial.ko is used. This causes the FTDI driver to not work as expected. The solution is to move the usbserial.ko file which causes the new file from Seeed Studio to be used.

cd /lib/modules/5.10.120-tegra/kernel/drivers/usb/serial/
sudo mv usbserial.ko usbserial.ko.bk

Additional Documentation

• VN100 Datasheet
• VN100 User Manual
• Inertial Navigation Primer
• Time Synchronization Application Note: Contact VectorNav for access

For any questions, please contact

• Nikhil Khedekar
• Morten Nissov
• Kostas Alexis