Rhoeby Dynamics R2D LiDAR ROS Node

The Rhoeby Dynamics R2D LiDAR is a small, light, low-cost scanner that uses IR (Infra-Red) ranging technology from TeraRanger (website: http://teraranger.com). This scanner is designed to replace more expensive laser-based products and avoids the eye-safety issues associated with those devices. For more information on the scanner, please see our website: http://www.rhoeby.com.

Specifications

• Scan rate: 1 - 5 Hz, user-configurable
• Scan range: 360 degrees, over 5 meters
• Angular resolution (minimum): 0.36 degrees (@ 1 Hz scan rate)
• Sample density: 250 - 1000 Samples/scan, user-configurable
• Size: 75 x 44 x 44 mm (with base enclosure)
• IR-based sensor

Quick instructions

1. install/build scanner2d ROS node

2. connect scanner via USB

3. run static tf publisher

rosrun tf static_transform_publisher 0.0 0.0 0.0 0.0 0.0 0.0 base_laser map 1000 &

4. run scanner2d node

rosrun scanner2d scanner2d _port_name:="/dev/ttyACM0"

5. view data in rviz (topic: '/laser_data', frame_id: 'base_laser')

Detailed instructions

1. install/build scanner2d ROS node

• download code from https://github.com/Rhoeby/scanner2d
• place code in sub-directory of catkin workspace
• do 'catkin_make'

2. connect scanner via USB

• plug in scanner
• type 'lsusb', you should see something like: "Bus 002 Device 074: ID 0483:5740 STMicroelectronics"
• confirm sensor blue LED is flashing
• you could verify binary data flow from the scanner, type: 'cat /dev/ttyACM0' (use Ctrl-C to exit)

3. run roscore

roscore &

4. run static tf publisher

   rosrun tf static_transform_publisher 0.0 0.0 0.0 0.0 0.0 0.0 base_laser map 1000 &

This allows the scan to be displayed in RViz by providing a transform from the frame of the scanner to the map.

5. run ROS node as shown here (it's using ttyS3, as an example):

   rosrun scanner2d scanner2d _port_name:="/dev/ttyS3" _scan_rate:=4

The default port name is "/dev/ttyACM0". If you are using a different port, you'll need to specify it on the command line.

6. Confirm scanner starts and speeds up to 240 rpm (4 rotations / sec)

7. run RViz

   rosrun rviz rviz

8. observe scanner plot data in rviz

• in rviz, select "Add"
• select "By topic" tab
• you should see '/laser_data' as a topic
• select LaserScan which appears under the topic
• hit OK

The LaserScan should now be presented in rviz. If you can see it, congratulations! If it does not work, try the Troubleshooting guide below.

Notes

When the ROS node is started, the scanner gets reset. As part of the reset, the scanner starts at a slow speed, then it speeds up to the operational scan rate (whatever is set on the command line). This is required to get the scanner initialized and into a known state prior to starting normal operation.

It's possible to run the scanner at different speeds. From the command-line, you could set the paramter 'scan_rate'. Actually, there are several parameters that can be set. Here is a sample command line:

rosrun scanner2d scanner2d _port_name:="/dev/ttyACM0" _scan_rate:=3 _sample_rejection:=0 _samples_per_scan:=333 _min_angle:=0 _max_angle:=360

These settings are added to the ROS parameter server when the driver is started.

Troubleshooting

Symptom:

Scanner fails to respond when ROS node is started (shows message "Waiting for reset CLEAR to complete...")

Solution:

1. run the following

cat /dev/ttyACM0 (or whatever device your scanner is on)

Is binary data presented?

If yes, restart the scanner ROS node, and try again.

If no, the problem is likely to be connectivity between the scanner and your Linux system... check you have it connected correctly and have specified the correct device (eg. /dev/ttyS2). Try unplug/plug.

Symptom:

When starting the scanner2d node, it reports: "[ERROR] [1427572321.434331608]: /dev/ttyACM0 open failed! " or similar

Solution:

Make sure you have permission to access '/dev/ttyACM0' (or other)

Symptom:

RViz does not display the scan

Solution:

Do the following:

• shutdown rviz (using Ctrl-C)

• shutdown the scanner2d node (using Ctrl-C)

• shutdown the static_transform_publisher

• shutdown roscore

• unplug scanner

• plug scanner back in

• restart roscore

• restart static_transform_publisher

• restart scanner2d node

• restart rviz

Symptom:

Scanner does not enumerate (does not show up as COM port) under Windows

Solution:

Unplug scanner from USB Select "scan for hardware changes" Plug in scanner