Atmospheric profiles with IRIS

Posted by Dan McKenna on February 2, 2015 at 4:59pm

Hi There,

I am measuring the temperature profile from ground to 100 meters.

At the moment I am using a data logger that records temperature altitude and humidity.

So far I have made all my flights by taking off and the doing a 3 meter loiter for a few seconds

then

upping the rate of climb to about 0.2 to 0.3 meters a second until reaching 100 meters, hold

altitude for a few seconds and then try to descend at the same rate that I climbed.

The data looks good and so I am looking to improve the instrumentation and technique. 

I will be adding a faster response temperature sensor and using the drone altitude data.

Question 1

Can I program the transmitter to use the unused channels to have a climb and descend function?

This would help me by not fiddling with the stick to obtain consistent results.

 

Question 2  

How do I add wind speed and direction to the telemetry stream?

I see the EKF2  VWE and VWN, yet on the log it is always zero.

At the moment I am trying to use Pitch and Roll angles to deduce wind force as I stay in one lat long and just go up and down.

Question 3

I would like to use an onboard A to D for the temperature measurement instead of mounting my data logger.

I am guessing that the IRIS Plus has at least a 12 bit converter and by adding a signal conditioner I could

make for a cleaner install

Thank you for your time

Dan

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Replies

  • Erik Graham February 2, 2015 at 7:10pm
    I got you. Also it would just be cool and pretty convenient to have switches set to do specific maneuvers, whether it be a simple ascend/descend or something else. When you figure it out, please post back. It's something I plan to look into myself at some point.

    Having said that, it occurs to me that a super simple way to do it would be to create an auto mission with only takeoff and land waypoints. NO location waypoints. That way you wouldn't have to fustz with resetting your "top" waypoint to somewhere above your head every time you change locations.

    Since Home is always wherever you arm the Iris, it should work.
    You set take off to 100 meters.
    You build in a pause at the top. Maybe throw in a RTL with a pause built in.
    Then you do the Land... except you set the land altitude to 3 meters.

    So as long as you have that mission loaded, all you would have to do is set the Iris down. Arm it. And flip the switch on your TX to Auto.

    You would never have to reprogram with your GCS, no matter where you are in the world. The Iris would always just take off, wait at the top, then "land" at 3 meters - at which point you could just let it hover there until you get your readings, then manually land it for real. Here's the catch... As you can probably surmise, I'm a bit of a noob here and I'm not really sure what would happen if you set your land altitude to 3 meters. I wouldn't be surprised if it just kept on landing. Nonetheless, I'm sure there is some way you could create a mission such that all you ever have to do is flip the auto switch on your TX.

    But again, please do post some links or tips when/if you find out how to reprogram your TX.

    Regarding wind speed... wouldnt all the prop wash make it impossible to get wind speed with a tube?
    • Dan McKenna > Erik Graham February 2, 2015 at 7:32pm

      Yes indeed Eric

      I just don't know how to make the switch do my bidding. I set a 3 meters loiter to get a return to ground temperature sample and 3 meters seems to be an altitude that I do not really worry about "under shoot", read crash.

      with the fine wire probes out, when I land, I do not want the extended legs to provide a pivot point so that the probes taste the earth. getting them fixed means sending them back for micro welding.

      I really do fuss over landing, kind of like the "oh no!" bird

       

      The pitot tube would need to extend so that prop wash was at best a minor issue and can be addressed partially by doing a helix up and down that provides for a little forward air speed other than than the wind. I expect from other data sets that I can process wind speed in 3 meter slabs.

      I saw that a previous incarnation of of droidplanner 2 did have a change altitude command....yet it disappeared in my last update.

      As I get faster data rates I can up my climb rate and as it is now, I am at 1.7 km elevation so at 0.2 meter/ sec I get one up/down before I change battery.

      regards

      Dan

    • Dan McKenna February 2, 2015 at 8:12pm

      Thanks Dax,

      It is the radio that ships with the IRIS +      FSTH9X?

      Really don't know the details and for me, that is uncomfortable  

      it has a label that says for use at an age over 15 years, I just about extended my landing gear

      when I read that, so to speak.

      I start on stabilize

      quickly t up and then switch to loiter.

      If it sticks to the position then wait a bit at 3 meters and then creep up on the throttle un till

      i get a slow climb

      watch the altitude telemetry to estimate the climb rate.

      so I am looking at my watch and it says 2015

      must be a better way

    • Dan McKenna February 27, 2015 at 9:46am

      No Problem Dax,

      Right now the angry bee is at 3DR and until it comes back will not have time
      to test the settings. I absolutely want to have a deterministic vertical rate control
      and welcome your information. I only have the stock radio supplied with the IRIS+

      Dan

  • This reply was deleted.
    • Dan McKenna February 2, 2015 at 6:59pm

      I am using temp sensors Type T .003 inch in diameter and in the air stream...away from the props

      has a settling time better than 0.1 seconds. On a tower mounted system I record at 100 HZ

      I would be happy at 10 HZ, another way is to preprocess the data with a arduino and send it to the IC2 buss

      I also thought about using the pitot tube and having the IRIS spin as it goes up proving a wind speed Vs Azimuth dataset.

      All ideas welcome

    • Dan McKenna February 2, 2015 at 7:55pm

      Dax,

      I have been programming all kinds of things for decades yet I really am holding back to modifying 

      the drone code. I have crashed to many things and what I have now, kind of works.

      I make measurements at sunrise and not always at my best.

      thus, even after in the loop simulations etc. I need to have everything on my side if we have a glitch.

      After all these years, i still freeze during critical moments and have watched my work...frag ment

      D.

  • Erik Graham February 2, 2015 at 5:31pm
    Re question 1.
    How about doing it all with an auto mission. Set params for WP Speed Up, etc to the exact speed you want (I think it's 2.5 meters per second by default).

    You could program the whole mission, including the pause at 3 meters and the pause at the top. Save it and re run the mission again and again in the same location or different locations (you'll obviously have to make some tweaks to your base mission if you change locations).

    Also, you could use the Land switch for the descent.

    Anyway. Just a thought.
    • Dan McKenna > Erik Graham February 2, 2015 at 5:56pm

      Yes, that was my first thought use the GCS to program auto mission.

      I would like to have a simple set up, goto location, initialize, and go and not to worry

      about my GCS.

      When I fly alone I do like the audio feedback of battery level and link status and do try to have it going.

This reply was deleted.