Lidar Lite v3 Irratic Measurement

Question

Hello Everyone!

I have a Garmin Lidar Lite v3.

There is an obstacle at 24" in from of the Lidar. About one percent of the time, the Lidar will give a measurement of about 14" or about 9".

What could possibly be happening?

Bruce

DAB · Accepted Answer

You could be getting reflections from more distant objects that are appearing in the next distance cycle. It depends upon the AGC they use and the chirp encoding. Given the price of the unit, I would expect it to have just minimal interference circuitry built in, so you will expect to see some erratic behavior. Is there a highly reflective target in the far field? Different reflectivity can introduce errors. DAB

the48sicks · Answer

Hi Bruce Mine does exactly the same, I think Douglas and DAB have it thouh. You can try setting the different modes for short/mid/long range to make it a bit more accurate. In the end I started taking 3 measurements and taking an average of the closest 2 results. Increases the scan time though so its not really ideal but it smooths things out a bit

the48sicks · Answer

Hi Bruce Im using the LIDARLite Arduino Library. It gives you options for config and scanning. When you call the distance method there is also a true/false parameter to scan with or without bias correction. Its recommended to run this every 100 scans or so https://github.com/garmin/LIDARLite_v3_Arduino_Library/archive/master.zip Parameters ------------------------------------------------------------------------------ configuration: Default 0. 0: Default mode, balanced performance. 1: Short range, high speed. Uses 0x1d maximum acquisition count. 2: Default range, higher speed short range. Turns on quick termination detection for faster measurements at short range (with decreased accuracy) 3: Maximum range. Uses 0xff maximum acquisition count. 4: High sensitivity detection. Overrides default valid measurement detection algorithm, and uses a threshold value for high sensitivity and noise. 5: Low sensitivity detection. Overrides default valid measurement detection algorithm, and uses a threshold value for low sensitivity and noise. lidarliteAddress: Default 0x62. Fill in new address here if changed. See operating manual for instructions. Hope this helps! Any questions please dont hesitate to ask Matt

the48sicks · Answer

Nice work! Its on by default, so you can run the method sending false as an argument, then every 100 add a true in there Looking at the comments on the method from the .cpp file ------------------------------------------------------------------------------ biasCorrection: Default true. Take aquisition with receiver bias correction. If set to false measurements will be faster. Receiver bias correction must be performed periodically. (e.g. 1 out of every 100 readings). Are you doing point clouds with your scanner?

brucewilsonph@yahoo.com.ph · Answer

For any Python users out there, you may find a configure method in my LidarLite3Ext class. It can be found at https://github.com/Z223I/LidarLite3Ext The Extension class also contains methods for threading. It is a producer/consumer model using the Python thread safe queue class. Best wishes! Bruce

brucewilsonph@yahoo.com.ph · Answer

No. I am not doing point clouds. It does sound interesting. Thank you everyone for your help! My robot works SO MUCH BETTER now.

dougw · Answer

Is it possible it is seeing some dust? You could try sprinkling some dust in the beam to see how much it takes to start getting erroneous data.

brucewilsonph@yahoo.com.ph · Answer

Here is the document that I am using: https://static.garmin.com/pumac/LIDAR_Lite_v3_Operation_Manual_and_Technical_Specifications.pdf Is it the same document that you are using? Apparently I am overlooking the close, mid and long range setting if it is. Thanks, Bruce

Lidar Lite v3 Irratic Measurement

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