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LidarLite working correctly? - SOLVED

Posted by Felix Meissner on April 28, 2015 at 3:40am

I am trying to set up a LidarLite sensor from PulsedLight.

I set it up according to the wiki (new sensor, manufactured Feb 2015, interfaced with a Pixhawk)

http://copter.ardupilot.com/wiki/common-optional-hardware/common-rangefinder-landingpage/common-rangefinder-lidarlite/

In the wiki it points to the Flight Data Screen to test the sensor,

but I only get zero as reading in this window.

But if I check in the terminal,

I can see that the sensor is working (see attached file),

so is it working ok? Is the wiki wrong?

Thanks a lot,

Felix

Capture.JPG

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Replies

Dom May 11, 2015 at 12:10pm

Hopefully the readings get adjusted till 3.3 Copter Final. I have "zero" readings with 38cm. When Copter is 1m over the ground, reading is ~1,40m - LIDAR is working perfectly with perfect and correct readings over arduino - So definitly a pixhawk problem. But I read about other people having this issue too.. And it seems you too Felix
- Distributor
  
  Felix Meissner > Dom May 11, 2015 at 2:19pm
  
  I didn't have much time for testing in the last few days, but I have as well a constant offset. On the ground it displays a value of ~ 30 (I saw that there is a parameter describing the sensor distance to the ground - but adjusting it didn't change anything). But it says that the sensor doesn't produce reliable readings close to the ground (<20 cm), mine is mounted 12 cm above the ground, so maybe that's the reason for the ~ 30 value ...
  
  If I lift it up it produces pretty good measurements, even though they are all offset by about 15 cm ...
  - Dom > Felix Meissner May 11, 2015 at 10:36pm
    
    Mine produces always a Offset about +40cm +/-5cm -Even when Holding it 2m above the ground. So the 20cm Thing is definitly not the issue. - I already get a reading of 50cm, when my landing gear is extracted -> Prearm check useless for me ;) Adjusting the Offset values in the param list of the pixhawk does not have any effect.
    
    I thought my lidar needs to be calibrated - But suprise. When connecting it with Arduino it produces perfect values and Shows "Zero" when the laser is completly hidden
    
    I dont think ist a big Problem in practice but why spending 100USD for a "high precision laser distance measuring System" when getting 40cm Offset values ;) That Comes in my mind
    - Developer
      
      Grant Morphett > Dom May 13, 2015 at 3:12am
      
      Hi. Is your scaling parameter set correctly?
      
      http://plane.ardupilot.com/wiki/arduplane-parameters/#rangefinder_s...
      
      Thanks, Grant
Distributor

Felix Meissner May 3, 2015 at 3:32am

I did fly today with AC 3.3 RC3 - LidarLite works :)
- Robert Szabo > Felix Meissner May 3, 2015 at 11:19am
  
  I flew Lidar (pwm) with AC3.3 rc3 too - works well in alt hold. however ... I am not sure but my feeling was that the copter loses altitude as I change pitch ... Is it possible that as the pitch changes and the Lidar does not measure straight ground distance but does it from an angle the FC does not correct the raw altitude info ? Again, it was only a cople of minutes atl hold test in strong wind so not absolutely sure
  - Distributor
    
    Felix Meissner > Robert Szabo May 4, 2015 at 10:24am
    
    that's something I wanted to test too - I will report back.
- MR60
  
  Hugues > Felix Meissner May 3, 2015 at 4:26am
  
  Thx Felix for bedugging lidar lite and wiki documentation. It will save me a lot of time as I intend to install one on my XUAV Talon. I can't find it for sale on your web site though ?
  - Distributor
    
    Felix Meissner > Hugues May 3, 2015 at 4:33am
    
    it will be available on the website this evening
    
    :)
    - Distributor
      
      Felix Meissner > Felix Meissner May 3, 2015 at 5:38am