FS2Phidget... what support for servos?

[JBaymore]

Does the FS2Phidget program have the ability to relate values to servos in some manner?

In other words... can I assign "servo#1" to rotate to a specific position based on the value of an offset in FSUIPC? Example...... flaps indicator. If the flaps are at 1... move to this position. If the flaps are at 30.... move to this position. And so on.

best,

......................john

[alandyer]

John,

Here's current functionality:
- you can specify the minimum and maximum range that a servo can travel.
e.g. you can specify that servo must only travel between 45 and 135 degrees of
its full 0-180 degree range.
Default is full travel.
- Software will move servo a proportional amount through this range.
e.g. if FS Flap Control value is at 0 in the range -16383 to 16383 (half-way in range) then servo will be set to position of 90 degrees (half-way between 45 and 135 degrees).

Regards,
Alan.

[JBaymore]

Alan,

Thanks for the info. So that says I can make a flaps position indicator easliy if I restrict the "full scale" guage face image to occupying only 180 degress of the face. A 1- to - 1 linkage. Not exactly realistic from the real world ones... but "close enough for government werk". ;)

Any recommendation on the lightest servo that would serve to move only a pointer on a fake guage?

By the way... I had sent you via PM my email address at your request so that you could send a "beta" of the FS2Phidgets software. Did you get it.


best,

...................john

[alandyer]

The restriction of 180 degrees is mechanical limit.
Most servos only have 0 - 180 degrees of travel.
If you find a server with a greater range it is supported by software.
You can specifiy the maximum travel.

Did not get your email.
What is PM ?

[JBaymore]

Alan,

PM is "private message". I clicked on your name here in the forum and it said something like "send this member a Private Message".

I'll have to do a web search for a higher travel servo. Needless to say... I know NOTHING about servos and robotics and such :rolleyes: .

best,

........................john

[Steve Daly]

John,

I'll help you through the mysteries of servos. :)

I know a few things about them...built my first R/C model ship 28 years ago. I've even still got the original radio and one fo the servos, in working order.


Any recommendation on the lightest servo that would serve to move only a pointer on a fake guage?

The smallest made will drive a single needle...as long as the system is relatively slop free. I would suggest you get something in the standard size ranges though. Servo prices are like a valley in cross section: Standard in the middle and smaller, faster, stronger all having positions on the surrounding hils.

The servo output shaft can also be geared...meaning that a standard 90 deg servo (actual travel about 135 deg) can easily drive the tail-end object 180/360...as long as you remember that if it goes one way it has to come back the opposite direction. Model boaters uch as myself often do this to drive gun turrets, it's a lot cheaper than buying 180 deg servos! If you decide to buy 180 deg servos, stay away from those marked "Gear Retraction" unless they are also labelled as proportional. Many gear servos are bipolar...they can only go to the limits with no stops in between, not very useful.

Show me a graphic of the guage face you want to drive and I'll help you get a setup that will do the job with good accuracy without resorting to specialized (high priced) options.

[alandyer]

John,

If you download fs2phidgets.zip you will see it now contains
Beta3.0.zip

The beta zip contains:

FS2PhidgetBeta30.exe
readme.txt

The readme has overview of new features and enhancements.
I did make a last minute change to improve performance.

Check it out and give me some feedback.

Regards,
Alan.

[JBaymore]

Alan,

Thanks for the Beta upload. I got it but haven't had a chance to test it out yet.

Steve,

Thanks for the ofer of help on the servo issue. I'll take you up on it. :)



Alan and Steve...........please take a look at the diagram I have done up for an idea for a whiskey compass located at the URL below, and tell me what you think.

Homebuild Cockpits Forum message at Simvation (http://www.simviation.com/cgi-bin/yabb/YaBB.cgi?board=homebuild;action=display;num=1113870876;start)


best,

..................john

[Steve Daly]

Originally posted in response to John's question over at SimV:


Sadly, no it won't work.

Modification to a servo to make it turn 360 degrees removes the feedback ability...the servo no longer knows where it is pointed.

What might work is to add a rotary encoder to the servo output. The encoder could pass the position back to the Phidget so that the system would know where the output was. I don't think that the programming exists in FS2Phidgets to use that feedback, but the guy who wrote it seems cool and might add the capability if asked nice. :)

I do like the idea of magnetically coupling the pices together...vary the distance slightly and you can get the typical "Whiskey Compass Hunt" and is lags behind and the oscillates and overswings a little bit.

For my own Whiskey compass I was thinking of gearing a standard servo output by 1:4...the output is then 360, plus a little bit of available over travel. The only hangup is that when rotating past end-of-travel points the servo would have to swing all the other way around. :(

I can live with that limitation...but if the software can be tweaked to allow your idea, well I'll go another way. :)

Alan:

Please note my comment about the rotary encoder:

What might work is to add a rotary encoder to the servo output. The encoder could pass the position back to the Phidget so that the system would know where the output was. I don't think that the programming exists in FS2Phidgets to use that feedback, but the guy who wrote it seems cool and might add the capability if asked nice. :)

Any chance that something like this could be done? It would greatly simplify any tasks that are done in simpits using servos...like the vast majority of instruments. It wouldn't be anywhere near as accurate as the self correcting systems that some have worked out...but a manual "calibration" scheme isn't that hard. It would need 3 switches:

One to scroll the output up.
One to scroll the output down.
One to tell the output it is now calibrated.

The first two switches could even be replaced by a rotary encoder...use two rotary encoders and one switch and you can select any instrument possible, adjust it and then tell the system that it's calibrated.

Thoughts?

[Steve Daly]

I had a thought about controlling 360 deg servos.

I modified John's picture over at Simviation to show what I mean, but the idea is very simple.

What it is:

On the servo output you add an optical encoder disk. This disk would be clear with opaque sections marking "calibration positions". The encoder disk is fitted through the slot of an optical interrupter. The interrupter feeds it's info back to a Phidget as a pulse train.

How it works:

As the servo turns the encoder disk turns as well. This brings the opaque sections through the interrupter. The interrupter reads the opaque sections and outputs a pulse train, if the disk is marked with definable positions at certain locations then the Phidget can read those positions and update the system. Such a feedback system would be useable in more than just cockpits...any place where 360 degree servos are used could use it. Obvious applications in Robotics exist.

Advantages:
Self calibrating
Calibrates continuously as it rotates
Applications across many fields
Simple to build
Inexpensive hardware