Plane: Advanced Servo Mixing

[geofrancis]

Now that arduplane has separate servo output and function parameters the logical next step would be to allow more than one function per servo similar to the mixer page on opentx.

so you could have a A for aileron E for elevator T for throttle R for rudder F for Flaps B for airbrakes

servo_1_mix parameter with value "A100E100" servo_2_mix parameter with value "A-100E100" servo_3_mix parameter with value "T100" would be a basic flying wing.

servo_1_mix parameter with value "A100B100" servo_2_mix parameter with value "B-100F-100" servo_3_mix parameter with value "B-100F-100" servo_4_mix parameter with value "A-100B100"

for crow mixing on a glider wing you would use a mix of flaps and airbrakes for the inner flap servos and airbrakes and aileron for the outer wing servos

you could simplify it by just having value of "AE" without the values and use the rc in trims to sort out the ratios or just in 10% steps so it would just be A10E10 for 100%

or to simplify it more have multiple values in the servo function box aileron/elevator using current function numbers servo_1_function parameter with value "4/19" servo_2_function parameter with value "-4/19"

would give you elevons

because could have multiple functions per servo giving you things like crow mixing, speed brakes, split elevons for yaw etc without all the problems people are facing now when they try and build an exotic setup.

It would also make a lot of the current parameters redundant since you wouldn't need the parameters for elevon mixing, vtail, rudder/aileron mixing, flaperons, mix gain, to name a few since all that would be taken care of within the servo mix parameter.

this would also work with dual motor planes since you could mix some rudder into the motors.

[955Ydfgg]

Great to learn that mixing can be more flexible using OpenTx. I want to accomplish something similar, but I need to stick to Arduplane Firmware modification to fit my application. What I essentially need is to vary the output to Four RCn outputs, which currently only depend on Roll angle, (Aileron-type RCn_Function) as a function of Roll and Pitch angle (sth. like Mixing_Offset and Mixing_Gain for Elevons, but with those parameters different for each output, and functionally dependent on Roll and Pitch angle). Do you know whether somebody is already working on similar firmware modification?

[tridge]

I do want to add mixing of this type, and I had planned to do it in a similar way to what @geofrancis describes. I haven't started on an implementation though. If someone else wants to start prototyping this then that would be great.

[geofrancis]

I am willing to test anything anyone comes up with, I really think this along with #6903 could really transform ardupilot in a radical way, it would open up so many possibilities and it could eliminate so many parameters, from wing and tail mixing, speed brakes, ic engine control, auto landing gear, failsafes, auto flaps, you wouldnt have to add more parameters every time somone wanted a feature since it could be all done with custom mixers and logic.

The best flight control software I have found in terms of airframe flexibility is openaeroVTOL, it has 2 tuning pages, one for hover and one for forward flight and it can transition between them, you can select how much of each input, gyro and auto level goes to each servo and motor channel so you can make it fly just about anything you can think of by changing the settings on the kk2 screen. because you can set everything you dont need hard coded airframe types.

[Ryanf55]

Hello, I'd like to help contribute in testing. I have a full house powered glider that uses advanced wing functions such as flaps, flaperson, crow, reflex, camber, and differential. I was tasked last year with replicating all these in Pixhawk and got most of the way there. I'd love to try any new mixers or help draft a good way to setup mixes. Thanks!

[Ryanf55]

Is there any update on the new mixer or any plan been developed for implementation? It seems like a few ideas were bouncing around but nothing was quite decided.

[bart989]

Isn't a LUA scripts a good option for this?

[RFRIEDM-Trimble]

No, Lua is not intended to control critical flight surfaces because the scripts are not safe from being terminated. I can't find a reference on this right now but do remember reading it.

[bart989]

Well I've read it on the documentation on LUA scripts. Also not very happy with "low priorytet". But as I have tiltwing I didn't found a better option to make ailerons steer with yaw in vertical mode. How is model type specified? Maybe if you make a custom type, but I haven't found good instruction for this.

[IamPete1]

The go to method for this is scripting, pcalls can make them more robust. You can read in the normal aileron, elevator ect output functions, mix them however you like and then output to the dedicated scripting functions.