Development discussion of TauLabs software such as ground control stations, antenna trackers etc.
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RVCTinker

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Mixer/Software Setup for a new type of flying object

by RVCTinker » Sun Jan 24, 2016 5:01 am

Greetings Airborn Peoples,

For a project for school, my son has developed a 'flying cube' if you will, consisting of an EDF (electric ducted fan) with four servos controlling fins to direct where it is going.

Nothing in OpenPilot or Taulabs GCS can handle this type of setup, unless somebody knows some trick?

The throttle controls how high/low it goes - that one is simple. The problem is that by moving the fins, we can go in any direction in a 2 dimensional plane, with a couple of the fins having to be constantly slanted a bit to compensate for the torque of the EDF - kind of like the tail rotor of a helicopter.

I thought the helicopter type would work, but alas everything wants the input controls to be specified in terms of roll, pitch, and yaw (collective for helicopter) but what we need is 'arcade drive' (left, right, forward, back) which controls the four servos.

Using the mixer setup, I can get servos in the same orientation operating together, but only in one direction.

We are using a CC3D controller right now and would like to use that with Taulabs GCS, but it just doesn't seem to me that it is possible - anybody know of a way that I am wrong?

If I connect the remote receiver outputs directly to the servos, then I lose all of the nice telemetry and auto positioning features of a flight controller. If I use an arduino to get better control of the servos, then I have to use the serial interface to get telemetry data from the CC3D and that will cause a LOT of extra programming.

Thanks in advance for any ideas on this one!

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peabody124

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Re: Mixer/Software Setup for a new type of flying object

by peabody124 » Mon Jan 25, 2016 1:14 pm

Most things can be controlled via the mixer (which is essentially a matrix). You don't want to use a preconfigured thing though, you want to go custom and manually make the entries.

Without knowing the geometries of all your surfaces it is basically impossible to blindly suggest things, but you should be able to try around and make the surfaces do what you want.
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RVCTinker

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Re: Mixer/Software Setup for a new type of flying object

by RVCTinker » Mon Jan 25, 2016 2:48 pm

Here is my experience with the mixer: I need to have two servos controlled by one channel from the transmitter e.g. a single joystick. If I put 127 in for both servos for pitch for example, then from the center of the joystick to the top, I can control both servos together, but only in one direction (0 to 127). If I put 127 for one servo and -127 for the other, then the positive (up) part of the joystick controls one, the lower (down) part of the joystick controls the other, but they are again only operating in one direction. I need to tie two servos to a single control using its full range from -127 to 127, but I'll be damned if I can figure out how to make that happen!
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piglet_74

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Re: Mixer/Software Setup for a new type of flying object

by piglet_74 » Mon Jan 25, 2016 3:02 pm

I saw someone who made a stick fly. It was pretty cool. I'm trying to find the project but I came across some others in the meantime:

http://diydrones.com/profiles/blogs/rct ... ed-vehicle

Here he is!

https://www.youtube.com/watch?v=XxyqklMx96I

Hopefully there's some useful info in there.
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RVCTinker

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Re: Mixer/Software Setup for a new type of flying object

by RVCTinker » Mon Jan 25, 2016 4:10 pm

piglet_74 wrote:Hopefully there's some useful info in there.


One is very similar to ours. Here is what we hope to get flying... https://youtu.be/TPH0vOxDMbo
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pug398

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Re: Mixer/Software Setup for a new type of flying object

by pug398 » Mon Jan 25, 2016 8:40 pm

Have you tried using the custom mixer? Say set output1 to motor and set the throttle curve for it. Then set 2,3,4,5 output for servo type. Enter numbers on pitch line for the servo channels you want affected when stick/craft is pitched. Same for roll and yaw. The servo center is set by the sliders on the output page. You move the slider to 1500uS in case of 1000uS to 2000uS output pulse for servos. I think there is a mixing issue if you use 127 and that is why you always see max of 63-64.
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RVCTinker

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Re: Mixer/Software Setup for a new type of flying object

by RVCTinker » Mon Jan 25, 2016 9:06 pm

pug398 wrote:Have you tried using the custom mixer? Say set output1 to motor and set the throttle curve for it. Then set 2,3,4,5 output for servo type. Enter numbers on pitch line for the servo channels you want affected when stick/craft is pitched. Same for roll and yaw. The servo center is set by the sliders on the output page. You move the slider to 1500uS in case of 1000uS to 2000uS output pulse for servos. I think there is a mixing issue if you use 127 and that is why you always see max of 63-64.


Yes, that is what I did, but no matter what it won't use the full range for the servos from -127 to 127. If I enter -127, then it uses -127 to 0. If I enter 127, then it uses 0 to 127. No way that I can tell to get it to use -127 to 127.
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icee

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Re: Mixer/Software Setup for a new type of flying object

by icee » Mon Jan 25, 2016 9:11 pm

Yes, that is what I did, but no matter what it won't use the full range for the servos from -127 to 127. If I enter -127, then it uses -127 to 0. If I enter 127, then it uses 0 to 127. No way that I can tell to get it to use -127 to 127.


The input "pitch" has a range of -1.0f to 1.0f. (pseudocode) The mixer calculates pitch * pitchMixerValue / 127.0f + roll * rollMixerValue / 127.0f ... to come up with a new number of the range -1.0f to 1.0f. E.g. a value of 127 will pass through the input pitch value to the servo unaltered (with full range). A value of -127 will pass through the input pitch value to the servo inverted.

Values between -1.0f and 0.0f are scaled to the range output min .. neutral. Values between 0.0f and 1.0f are scaled to the range neutral .. output max.

You should be able to get the behavior you want between the positioning of the "neutral" value and the mixer.
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Laurakep

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Mixer/Software Setup for a new type of flying object

by Laurakep » Tue Nov 08, 2016 4:01 pm

I have heard a whisper that v4.11 is on the go for the 797, still being tested, not availble to the public yet. Anyone else heard of this?

Any ideas when its going to be released?

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