UR-50 Long Range LiDAR

When changing out sensors makes sure to disconnect the RED battery cable from the batteries and wait 2 minutes so high voltage and current are not linked with the main board!

This tutorial is intended for magni_robot branch: indigo-devel and ROS Kinetic.

Installation

Connect the lidar lan cable into Raspberry Pi lan port and the power supply connector into the right molex connector on the MCB board:

Using 4xM3 screws, the lidar can be mounted on the top plate that comes with Magni robot

Now the batteries can be reconnected and the robot powered on.

Default location

The default location of the lidar is on the top plate looking into the forward direction (lidar connector is turned backward). Top plate of newer robots comes ready with holes for lidar mounting. But some of the older versions don’t have those holes. In that case please either contact Ubiquity Robotics to supply you with a new top plate OR use double sided tape to mount the lidar. If you chose to mount the lidar with the double sided tape please make sure its 1.) turned exactly forward - a slight offset in angle can result in inaccurate localization and 2.) its center is EXACTLY the position shown on the picture.

On the picture red, green, blue correspond to x, y and z axis. Lidar is the component that says ‘laser’ on the image (lidars are sometimes also called lasers)

Advanced: Changing LIDAR internal IP settings

Warning: IPs are changed from their defaults, it is highly likely nothing will work out of the box with Ubiquity Robotics products.

If buying a lidar from Ubiquity Robotics, the lidar will come pre-set with the IPs that were used in these tutorials:

• LIDAR IP: 192.168.42.222
• IP to which lidar is connected (workstation IP): 192.168.42.125

If you want to change those lidar-internal IPs here is a video about how to do that.

Additionally to whats shown on the video, make sure:

1. First make sure you have WinPcap installed (sourced here or download from the internet)
2. Follow the steps shown on the video to change the LIDAR IP, but a couple of notes:
   • in the video PC IP is changed from 192.168.1.125 to 192.168.42.125. This was done because often external network is also on the subnet 192.168.1.xxx and this creates problems with the internet connection.
   • in the video the IP is changed to 192.168.42.125 -> this is arbitrary and can be any IP

Setup to work with RaspberryPi

Network

The lidar should come pre-configured with static IP: 192.168.42.222 and only answering to requests coming from IP 192.168.42.125, so we need to configure that on the RPI.

A static interface needs to be set on RPIs lan port by editing the interfaces file

sudo nano /etc/network/interfaces

we need the eth0 interface to have a static address of 192.168.42.125/24:

auto eth0
iface eth0 inet static
address 192.168.42.125/24 #this IP may depend on your lidar settings
gateway 0.0.0.0
dns-nameservers 8.8.8.8

Compiling

cd ~/catkin_ws/src
git clone https://github.com/LS-Technical-Supporter/LS-LIDAR-N301ROS.git
cd ~/catkin_ws/
catkin_make

Running

cd ~/catkin_ws/
source devel/setup.bash
roslaunch lslidar_n301_decoder lslidar_n301_config.launch device_IP:=192.168.42.222

Default lidar extrinsics

The lidar position that is going to be loaded when robot starts up can be set in /etc/ubiquity/robot.yaml:

sudo nano /etc/ubiquity/robot.yaml

which should, among other things also contain:

lidar_installed: True

Example: Adding a custom lidar location

If the lidar is set in a different position, readjust its coordinates in the urdf files. Example:

<origin xyz="0 0.1 0.4" rpy="0 0 0"/> <!--change lidar pose here-->