Capturing Joystick input for non-traditional uses

[cbaye]

I originally posted this on AVSIM but got no response, perhaps a member of this forum can provide some insight.

- CB

I have a nice home cockpit with lots of gadgets; but when I travel I like to use my laptop and gamepad (for it's compact size) to fly. The game pad does not feature a sliding throttle control like most joysticks have.

I want to develop an alternate throttle control using the input from a self-centering joystick on a game pad. I Plan to use this feature with Jets only, so I think it might be possible to map a prop joystick axis as my input. FWIW, I have a registered copy of FSUIPC.

Design Intent: The joystick input range will be divided into 5 zones: Null, Slow change, Fast change With changes in both the positive and negative directions. When the Joystick is in the null position, the throttle condition (% throttle) will remain fixed. In the +Slow zone it will slowly advance the throttle, in the +Fast zone it will quickly advance the throttle. Retarding the throttle will work the same way as -Slow and -Fast zones. The null zone will be quite wide to avoid changing the throttle as the second axis of joystick is used.

Here are my questions:

Will this approach work... i.e. if I use the prop-pitch axis or cowling axis while flying a jet will do I run a high risk of having an unstable system?

Has anybody done anything like this in the past that I might use as an example?

Thanks,

- Chris

[Frank.O]

Hi Chris,

if I were you I wouldn't make it that complicated. Why not use a pair of buttons and assign the throttle increase/decrease controls available in FS to them. You don't even need to use FSUIPC for this. Just make the assignments in FS and activate the repeat function. If you want a slow change just tap on the respective button repeatedly, if you want a fast change keep holding it down. That's how I did it with prop and mixture until I got better hardware.

And even easier - you could use the assignments that are already there in FS on F1-F4 (idle/dec/incr/full). I mean you have the keyboard in reach when you fly on a laptop, haven't you.

Regards,

Frank

[cbaye]

Hello Frank,

Thanks for the reply.

I use both of the methods you suggested and find that I am looking for a more flexible method of control. I have used joysitcks with my laptop and have found most of them too bulky (and a little geeky) to travel with. The game controller was a nice compromise; it has 4 joystick-axes, a hat switch and 10 buttons. In a way I am trying to emulate Radio-Control style Elevator, Aileron, Rudder and Throttle control.

Flying from a laptop is a compromise at best. I use my manual controls only in the early and final stages of flight and taxi. Once my hands are on the gamepad I'd prefer to keep them there rather than have to operate the pad with one hand and the KB/Mouse with the other.

What I did not say in my original "design intent" statement is that I intend to implement this as a gauge and then put some logic behind certain behaviors. For instance, the thrust reverser function will be locked-out unless the aircraft is correctly configured, on the ground, and at appropriate speeds for safe operation. The function can only be activated if the throttles have been resting at idle for a set period of time (say 1 second).

[tuomas]

Chris, build a small 5-axis control using the USBAxis card from http://www.opencockpits.com and 5 slider pots. You can have a bunch of buttons too.

Get a small slim aluminium box from an electronics store and cut holes for the sliders on top - basically it could look like a small audio mixer table, with some buttons. Then map one or two of the sliders for throttle and whatever you need. 5 axis is quite useful and it all connects with just USB without extra drivers needed.

You can make it look REALLY nice if you have the top panel done with FrontDesign (http://www.schaeffer-ag.de / frontpanelexpress.com) - you can have the holes precision-cut for the buttons and potentiometer sliders. And it can have engraved text legends and such. It'd look very pro, not so geeky.. :)

//Tuomas