Using Breaking Ground for quadcopter style flight control?

[aryeh56]

Hi everyone,

I recently picked up the Breaking Ground Expansion and I've really been enjoying it. I'm really impressed with the versatility of the robotics system, but I seem to have run into its upper limit. I'm trying to make a craft which hovers on four motors and pitches and rolls by adjusting the throttle in each motor independently. Effectively, I need what 'absolute mode' does in the control editor, but making small changes relative to overall throttle position instead of just jumping between 0, 50, and 100. Is anyone aware of a way to do this? I haven't figured anything out yet.

The closest I've come is by running a KAL1000 in pitch control in absolute mode with different thrust values in the KAL's beginning, mid, and end points. This achieves the desired result, but only for one axis, and only at full main throttle.

I can't seem to come up with a better solution for this. It is annoying that when something is activated in relative mode on pitch, yaw, or roll the value does not return to it's starting point when you release the key.

I'd really appreciate any suggestions! Happy flying!

[AHHans]

What kind of "motors" are you talking about? Jet / rocket engines or (electric) rotors with (helicopter) blades attached to it?

What works quite well for me is a quadcopter with four electric rotors and helicopter blades. In order to have a separate collective control I attached the blades not directly to the rotors but with a small rotation servo in between to set the collective pitch of the blades. Cyclic control is done by using the blades as "regular" control surfaces. Because the blades are always clearly on one side of the center-of-mass of the craft, KSP doesn't get confused whether an individual blade should generate more or less lift as a result of a control input. Then I set up the target angle on the servos to be "incremental control" on one axis (I chose the translate forward/back), and set the rotor torque to be controlled by the throttle.

P.S.: If you plan to use robotic parts for control, the please no that SAS doesn't use the yaw/ pitch / roll axis groups:

 

Edited September 25, 2019 by AHHans
Added P.S.

[Fierce Wolf]

Is there a tutorial for building quadcopters? I want one!

[aryeh56]

4 hours ago, AHHans said:

What kind of "motors" are you talking about? Jet / rocket engines or (electric) rotors with (helicopter) blades attached to it?

 

Its Jets for me, frustratingly. I'm trying to build a cargo VTOL. Your solution sounds pretty great for rotors though. I'll remember that!

[AHHans]

3 hours ago, aryeh56 said:

Its Jets for me, frustratingly. I'm trying to build a cargo VTOL.

Well, about jet VTOLs the only useful comment that I have is that the gimbal range of the  J-404 "Panther" makes it a good choice.

Hmmmm... *sound of gears grinding* hmmmm... O.K. you want to have kind of two input for the thrust setting of each engine: a general (collective) that defines how hard the engine lifts your craft and some modification on that modifies that thrust a bit to pitch / roll your craft (in a helicopter this would be the cyclic). Unfortunately that cannot (yet?) be done directly with the KAL-1000.

What may work is to set the thrust limiter with a KAL-1000 to modify the thrust limit of the jet engines. Set it to change the limit from e.g. 80% to 100% for the engines on one side and from 100% to 80% for the engines on the other side. Then the play position in the center will have both at 90%, i.e. same thrust on both sides, but changing the play position will give more thrust on one side or the other. If that works that should give you pitch or roll control. Hmmm... and for both you could double up the engines. I.e. not have four engines, but have four pairs of engines. And then use one of each pair for pitch and the other for roll.

3 hours ago, Fierce Wolf said:

Is there a tutorial for building quadcopters? I want one!

Have you tried building a quadcopter from what I wrote earlier? If you think it will help you then I could also put my basic quadcopter onto KerbalX.

[Fierce Wolf]

18 hours ago, AHHans said:

Have you tried building a quadcopter from what I wrote earlier? If you think it will help you then I could also put my basic quadcopter onto KerbalX.

Yes please

[AHHans]

4 hours ago, Fierce Wolf said:

22 hours ago, AHHans said:

If you think it will help you then I could also put my basic quadcopter onto KerbalX.

Yes please

Warjaklar.(*)

O.K. Here it is: https://kerbalx.com/AHHans/Basic-Quadcopter

P.S. (*) Yes, that's German. After a fashion.