1. Default Python version: Since ROS melodic is used, the default python version should be python2, which means /usr/bin/python should point to /usr/bin/python2 (or self installed python2). If not, please use sudo update-alternatives --install /usr/bin/python python /usr/bin/python2 1 and sudo update-alternatives --config python to configure it.

2. Intel® RealSense™ SDK 2.0: A cross-platform library for Intel® RealSense™ depth cameras. More details are in this link.

   For Jetson, Librealsense2 SDK supports two API (mutually-exclusive) for communication with RealSense device on Linux platforms:

   1. Linux native kernel drivers for UVC, USB and HID (Video4Linux and IIO respectively)
   2. Using RSUSB - user-space implementation of the UVC and HID data protocols, encapsulated and activated by selecting the SDK's -DFORCE_RSUSB_BACKEND flag (a.k.a. -DFORCE_LIBUVC with SDK versions prior to v.2.30).

   More details are here.

   Choose one from below:

   2.1 Linux native kernel drivers (Recommended but hard)

   Get the source code from the librealsense repository and modify patch-realsense-ubuntu-L4T.sh according to the Jetson and L4T version.

   ./scripts/patch-realsense-ubuntu-L4T.sh  
   sudo apt-get install git libssl-dev libusb-1.0-0-dev pkg-config libgtk-3-dev -y
   ./scripts/setup_udev_rules.sh  
   mkdir build && cd build  
   cmake .. -DBUILD_EXAMPLES=true -DCMAKE_BUILD_TYPE=release -DFORCE_RSUSB_BACKEND=false -DBUILD_WITH_CUDA=true && make -j$(($(nproc)-1)) && sudo make install
   

   2.2 Using RSUSB (Easy)

   sudo apt install ros-melodic-librealsense2

3. OpenCV library: For Jetson users, the default OpenCV library location is different from what is defined in the ros camera build. Therefore, the following cammands are necessary.

sudo ln -s /usr/include/opencv4/opencv2/ /usr/include/opencv
sudo ln -s /usr/include/opencv4/opencv2/ /usr/include/opencv2

1. Put the sensor folder under the src in the catkin workspace directory

2. Install rosdep package if it is not installed by sudo apt-get install python-rosdep. Inside your workspace, install and update all dependencies by using rosdep install --from-paths src --ignore-src --rosdistro melodic -y

3. Use catkin_make when in the workspace directory

4. For development purpose (without catkin_make install), remember to use command source <workspace_path>/devel/setup.bash or source <workspace_path>/devel/setup.zsh depending on your shell

Default value: /dev/ttyACM0. sudo chmod 777 /dev/ttyACM0 command will be needed for the first time. Check in /dev/ folder in the OS. Need to adjust it in sensor/ublox/ublox_gps/config/zed_f9p.yaml file (according to the default launch file).

Default value: eth0. Check for the ethernet port name, type ifconfig -a or ip a in the terminal and identify the names of the ethernet port (normally eth0).

After connecting the ethernet cable to the Lidar, type in nmcli dev disconnect eth0 and sudo ifconfig eth0 192.168.1.x netmask 255.255.255.0. x is a number between 1 to 254, except 201, since the LIDAR's default static IP address is 192.168.1.201 (Do not change it).

To revert back to internet connection, type in nmcli dev disconnect eth0 and sudo dhclient -v eth0 with cable connected.

The setting is configured in the Jetson Xavier ("Lidar" network), remember to enable "Use this connection only for resources on its network" under IPv4 routes setting when using Lidar and Wifi.

Jetson settings: The Wifi IPv4 address is set to "192.168.2.22" with netmask 24, and the gateway is set to "192.168.2.1".

Connecting host settings: Set the Wifi (through Netgear) using address "192.168.2.x" (x could be any number from 2 to 254 except 22) with netmask 24. The gateway is also set to "192.168.2.1". For Windows, remember to set this network as private network.

Check in /dev/ folder in the file system. Need to adjust it in the launch file in sensor/realsense2_camera/launch/. The S/N for one of the cameras is 115422250478.

Simply use roslaunch sensor.launch!

For development and modification purpose, the individual launch files can be modified.

GPS: sensor/ublox/ublox_gps/launch/ublox_device.launch

Lidar: sensor/velodyn/velodyne_pointcloud/launch/VLP16_points.launch

Camera: sensor/realsense2_camera/launch/rs_camera.launch and sensor/realsense2_camera/launch/rs_multiple_devices.launch for multiple cameras

IMU: sensor/razor_imu_9dof/launch/razor-pub.launch and sensor/razor_imu_9dof/launch/razor-pub-diags.launch with diagnostics