3D Robotics

Another flight test of new ArduPilot 2.5 code

Here's a quick report on today's test flight of the latest ArduPilot 2.5 code, including a failed T3 contest run:

(I was using an EasyStar with XY & Z sensors)

The Good

--This version does away with the bind plug process for people who are using ArduPilot to control the throttle (which I am). Worked fine!

--Stabilization gains are dialed in fine. Earlier problems with people using the Z sensor are gone.

--Funky motor pulsing issues at startup and problems with ESC arming are gone.

--New GPS parser for uBlox works fine.

The Bad

--Altitude hold doesn't seem to be working in AUTO mode (although it does seem to work in RTL mode). The plane is supposed to stay at 50m, as you can see in the mission file above, but just seemed to go higher and higher. I had to bring it back manually from about 200m. We've had this problem before, and I think it has to do with the uBlox GPS parser. If it thinks the GPS is reporting that the plane is at an altitude of 0, it will just keep trying to fly higher. We'll need to fly with someone watching the telemetry to figure out what's going on.

--I accidentally set my waypoint radius limit too high (59m) so the plane was just approximately following the course. That should have been closer to 10m.

--The RTL loiter circles were more like figure eights. I think the loiter radius (45m) is too tight, and should be closer to 100m:
//4-7
#define LOITER_RADIUS 45 // radius in meters of a Loiter

The Stupid

Somehow I was under the impression that I could adjust the throttle while the plane was in AUTO mode (you can nudge the aileron/rudder and elevator in that mode). That doesn't appear to be the case. The reason this matters is that if you're trying to set a good time on a T3 run, you don't want the plane to leisurely go around at half throttle!

In the meantime, I need to change something in the settings below. I'm thinking I should crank the Absolute figure up, but how high? (Is it 0-10?). Jason, do you have some advice? Any chance we can allow the user to nudge the throttle when it's in AUTO mode?

//ATTITUDE: THROTTLE OUTPUT GAINS
//9-1
#define THROTTLE_ABSOLUTE 3 //Absolute
//9-2
#define THROTTLE_P .32 //Proportional
//9-3
#define THROTTLE_I .04 //Integrator
//9-4
#define THROTTLE_I_MAX 50 // (0-125) 50 = 40% Integrator limit.
//9-5
#define THROTTLE_CRUISE 30 // (0-125) 30 = 24% throttle, or (int)target airspeed for cruising
//9-6
#define THROTTLE_MAX 60 // (0-125) 60 = 48% maximum throttle
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Comments

  • Developer
    I'm preparing today for testing. I finally have my telemetry back up and running and I'll have a version that will control the throttle in AP so that you change change the throttle_cruise value on the fly.
  • Moderator
    Excellent! Any progress on the possible altitude hold problem?
  • Developer
    Hi Graham,
    The servo wiggle was disabled until we could sort out the throttle output and trim. Some planes were spinning up the prop or un-calibrtating the ESC. I think we have it sorted and I'll bring it back.
  • Wow, awesome update for the docs.

    http://code.google.com/p/ardupilot/wiki/ArduPilot
  • Moderator
    oh ok, I kinda liked the wiggle, that way there was a visual & audible indication of when the code finished uploading and a basic test that the servos were working too when plugging in the battery. No probs, I can always add it to my code.
  • 3D Robotics
    I think the Z is calibrating all the time the plane is in the air, in manual or auto, but I'd have to look at the code more close to be sure.

    The servo wiggle was removed when the bind plug process was removed in the latest version. No need for either anymore if you're letting ArduPilot control the throttle. The manual has been updated to reflect this.
  • Moderator
    Hi Chris, does it do that in manual (off) mode or only in one of the others? I've also noticed that the servo wiggle to confirm a reset has disappeared in v2.5.x?
  • 3D Robotics
    Yes, the Z sensor calibrates over the first few tens of seconds of level flight...it takes it a bit to dial in and stabilize. Faster if your gains are tuned..
  • Appreciate the response Chris. Everyone is doing great work here, just interested in how I can help with what I know.

    Here's the video of the flight. It brings one other question to mind, is the initial "drunk driver" effect a function of the Z sensor getting tuned in flight?

  • 3D Robotics
    John, many thanks for the data. We've obviously got some work to do on the altitude routine. We'll add a bunch of diagnostic code and record some flights to see what's going on.
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