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LidarLite working correctly? - SOLVED

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

Hi

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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Tags: lidar, lite, mission, pixhawk, planner, pulsedlight, rangefinder
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Replies

  • Distributor
    Felix Meissner January 26, 2016 at 10:35pm

    Hi

    this is the answer from PulsedLight:

    You’ve contacted PulsedLight Inc’s LIDAR-Lite help. PulsedLight was recently acquired by Garmin International and is working to transfer engineering and production to Garmin.

     
    LIDAR-Lite will be in production again.  Please check our website for updates.
  • Nick McCarthy January 25, 2016 at 9:49am

    Best I know, they unfortunately stopped production. It's not clear if Lidar Lite as a product will fit into Garmin's line-up, or if the technology will be integrated into other devices.

  • Nadia Nilsen January 25, 2016 at 6:05am

    I was hoping some of you might have more information about what is happening with the Lidar-Lite products?

    LIDAR-Lite v2 has been marked EOL.

    They were bought by Garmin recently: Garmin® Completes Acquisition of PulsedLight®

    Is there any information available about the status of their current and future UAV products?

    Thank you,

    LIDAR-Lite v2
    This is the LIDAR-Lite v2, a compact high performance optical distance measurement sensor from PulsedLight. The LIDAR-Lite "Blue Label" is ideal when…
    • Cool Dude > Nadia Nilsen March 26, 2016 at 11:57pm

      Robot shop was showing V2 as back ordered, still I went ahead and ordered it hoping to get it when it is back in stock. This was quiet a while back. However few days back I received a mail from robot shop stating that V2 is no more in production and garmin is working on V3 which will be available soon.

  • Nick McCarthy January 18, 2016 at 11:28am

    @ Felix and others:

    I'm using a Lidar-Lite v2 connected via I2C, and I'm trying to make sense of the readings. It seems to me that there is a scaling being applied. I'm seeing similar readings in Copter 3.3 as well as 3.4-dev

    Ruler (cm) Lidar (meters?) Lidar to cm (/100) Difference Scaling?
    30 1.12 112 82 3.7333333333
    60 2.3 230 170 3.8333333333
    90 3.15 315 225 3.5
    120 4.17 417 297 3.475
    150 5.18 518 368 3.4533333333
    180 6.23 623 443 3.4611111111
    215 7.35 735 520 3.4186046512

    The data certainly doesn't correlate well to the accurate, linear results Felix showed in his testing.

    RNGFND_TYPE: 4

    RNGFND_OFFSET: 0

    RNGFND_FUNCTION: 0 / Linear (only required for analog I believe)

    RNGFND_RMETRIC: 0 (only required for analog)

    RNGFND_SCALING: 1 ((only required for analog)

    Any idea what's going on here? I'm going to continue testing, as well as try PWM shortly.  Thanks!

    • Nick McCarthy > Nick McCarthy January 19, 2016 at 10:40am

      Thanks for the details Stephan, 

      I've just rewired my Lidar Lite to connect via PWM. Here's where things get baffling:

      sonarvoltage reads what appears to be proper voltage levels to distance: IE: 0.80 v for 80cm. This looks great - however:

      sonarrange for that value is reading 2.52. You would think I've got RNGFND_SCALING set to a value other than "1", but it's set correctly. Just as with i2c, there's some sort of scaling factor being applied - but I don't know what or where. I'm currently testing this on the Copter 3.3 release and have just reset default parameters and only set up the necessary Lidar params. 

      I can set RNGFND_SCALING to somewhere around 0.33 and get more approximate values for closer distances , but the scaling factor doesn't seem totally linear.

      I don't have a second Lidar, but I do have a second copter I will test this with to rule out something strange with this Pixhawk.

      • Nick McCarthy > Nick McCarthy January 19, 2016 at 1:30pm

        So I've connected this Lidar to another copter I have, currently running 3.4-dev. Using PWM, I see sonarvoltage and sonarrange both correlate well to actual distances.

        So it seems the problem resides with my original Pixhawk, on a 3DR Iris+. I can't think what would cause the unusual scaling issue, especially over both i2c and PWM, and different versions of firmware with parameters restored to defaults before configuring.

        I'll leave this here, just in case anyone else experiences this bizarre issue.

        • Nick McCarthy > Nick McCarthy January 19, 2016 at 2:07pm

          Problem Solved:

          After considering the strange Lidar readings I was getting, even in PWM where sonnarrange did not match sonarvoltage were not from the following:

          • Bad Lidar-Lite (Works fine on other copter)
          • Bad Params (reset to defaults)
          • Bad Firmware (Tried different builds of 3.3 and 3.4)
          • Bad I2C/PWM (Same values on both)
          • Bad 5V supply (tested okay)

          The issue was some sort of non-editable parameter and/or corruption in the Pixhawk's EEPROM.

          To Resolve the issue:

          I installed the firmware for APM:Plane, then reinstalled APM:Copter. By changing the vehicle type, the Pixhawk resets it's EEPROM.

          Then I reloaded my parameters back in, and using PWM, my sonarrange and sonarvoltage values correlate now.

          Definitely a weird one - I'll remember this fix for any other explainable issues. 

          • Nick McCarthy > Nick McCarthy January 23, 2016 at 8:06am

            And just like that, I'm having the problem again. This time on the new copter using PWM (where data initially looked good on first boot).

            Pretty dumb-founded on this one. I also switched to APM:Plane, where I'm seeing the same issue.

        • Distributor
          Felix Meissner > Nick McCarthy January 19, 2016 at 1:44pm

          how do you supply the 5V to the Lidar sensor?
          Can you maybe double check that the power supply is ok?

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