Ranger FLEX Initialization and Acquisition Workflow
Ranger FLEX Backpack LiDAR Initialization:
It is important to begin your data acquisition outside to allow the system to receive GPS time and record an initial position. PLS recommends approximately 5 minutes of Static time before and after acquisition.
PLS recommends a 10 second kinematic straight line walk and a figure eight at the speed of approximately 1.4 m/s before and after acquisition of your POI. More information can be found on the best practices page.
Ranger FLEX Acquisition Workflow:
Mount the Ranger FLEX to the backpack using the attached PLS Dovetail-Quick Release connection. Ensure the Quick Release is tight after locking by using a #4 Allen key to tighten the lock.
Connect the LEMO power cable and SMA GPS 1 and 2 cables. The GNSS receivers are labeled so make sure you are correctly attaching the correct GPS to the correct port.
Ensure the SD card is inserted in the NavBox on the LiDAR as highlighted in the picture below.
Check the XT60 connectors where they attach to the Battery trays. Ensure the battery trays are in good condition.
Make sure batteries are fully charged and install the batteries into the battery tray, the batteries will lock into place when installed correctly.
The Ranger FLEX backpack angle of the sensor can be adjusted by the user. The sensor angle can be set to 30, 45, and 90 degrees. For the Ranger FLEX we recommend either 30 or 45 degrees only. Check and confirm the acquisition angle for the sensor on the back pack matches the angle you wish to acquire at.
Although 30-degrees will likely lead to better point density for most applications, please remove the R6 camera using the thumbscrews prior to mounting the Ranger FLEX in order to prevent scratching or damage.
Extend and lock the GPS antennas out fully. The dual antenna setup can be raised and lowered manually. They lock in the up position automatically; to release them you need to push the lock release lever for each arm.
Power on the Ranger FLEX via the batteries. The batteries are TB47S DJI batteries. To power on each battery press the button once and release, then press the button again and hold until the NavBox and LiDAR LEDs power on.
Connection to the Ranger FLEX should be done via Wi-Fi through the web interface. Using an internet browser on your phone you can type the IP address 192.168.20.10. This will give you access to the mobile version of Spatial Explorer. From here you can turn the sensors on/off, monitor navigation statuses, and confirm the LiDAR is functioning properly.
In the mobile Spatial Explorer GUI, ensure the settings are correct and the correct profile is set for the angle of the backpack. (insert location in docs for this procedure of checking SE rover settings)
The system will need approximately 5 minutes of static time prior to starting acquisition. Capture will be enabled when “fine steering” is achieved. Once you activate and begin, you should see “fine steering” change to “Solution good”
Ensure the Angular range of the sensor is configured to capture the maximum FOV
It is recommended to select the reduced power measurement program in order to optimize the laser power for measurements of short range targets using the highest pulse repetition rate. This will reduce MTA ambiguities in short range mobile mapping applications. The table below shows recommended sensor configurations based on desired target range:
Recommended Sensor Configurations for Backpack-based LiDAR Acquisition
System | Target Range (m) | Measurement Program (PRR) | Lines Per Second (LPS)* |
Ranger-HA | 5 | VUX1-HA 1000 KHz (reduced laser power) | 200 |
| 20 | VUX1-HA 1000 KHz (reduced laser power) | 100 |
| 50 | VUX1-HA 1000 KHz (reduced laser power) | 65 |
Ranger-LR | 5 | VUX1-LR 820 KHz (reduced laser power) | 185 |
| 20 | VUX1-LR 820 KHz (reduced laser power) | 90 |
| 50 | VUX1-LR 820 KHz (reduced laser power) | 60 |
Ranger-UAV | 5 | VUX1-UAV 550 KHz (reduced laser power) | 150 |
| 20 | VUX1-UAV 550 KHz (reduced laser power) | 75 |
| 50 | VUX1-UAV 550 KHz (reduced laser power) | 50 |
*Recommended LPS computed based on the average walking speed of 1.3 meters/second for uniform point spacing at the desired target range
After activating the sensor, maintain a steady comfortable walking speed during your 10 sec kinematic alignment, figure-8 and throughout the entirety of the acquisition AOI. PLS recommends a walking speed of 1 - 1.4 m/s.
Maintain a good posture during collection to ensure proper angle of the sensor. Refrain from stopping, walking backwards, or turning at the waist while actively collecting in the AOI. See example below:
If possible, end your collection where you began. After collecting the AOI, complete with another 10 sec kinematic and figure-eight at a comfortable walking speed.
Turn the sensors off and allow the system to collect another 5 minutes of static time before shutting down the LiDAR completely.
The data is stored on the SD card located in the SD card slot on the PLS NavBox as seen in the image below.
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