My own UAVP: Part 12 - Throttle curve and Bluetooth
Created by Amir on the 12. Jun 2007 at 02:09 in UAVP | Permalink

We finally came round to hack the Wolferl software. As promised in ticket #7 we implemented a throttle curve for UAVPs with overpowered motors like ours.

The implementation was streight forward and when we finally realized that IGas does not get reset on each cycle but only when the RC interface receives a new value the hack was done within minutes. Tuning the throttle curve graph took a while longer.

This is what we came up with:

Implementation of the above throttle curve took place in revisions r170 and r171 in the subversion repository.

A short test and debugging session followed. During that time we plottet the IGas input and output values to see how our new throttle curve is behaving.

As you can see the new curve starts steeper (while we did not yet reach flight velocity) and a while (at 75) before we reach flight velocitoy (which is around 110-120) the new throttle curve starts to have a gradient of 1/2. This allows for a lot smoother control of the motors.

When we finally came round to a real flight test of the new patch we found out, that we were very successfull! Flying our overpowered motors has become a lot easier as you can see in the following short movie which we made while testing:

Get the Flash Plugin to see this movie.

Direct link: Download the FLV Movie, Download the WMV Movie (11.7MB)

We are pondering now, if we shall extend the throttle curve to a more general form where 3 different grantends and one free location of gradient change can be choosen or if the orginal solution is fine enough for everybody like it is.

We will see... further tests will follow.

Last but not least I need to tell you of my newest gadget. It's a Class 1 Bluetooth Serial Adaptor from IOGEAR. I've already cracked the housing and made some pictures of it.

This is the top:

and the downside:

It should be a able to do Bluetooth to RS232 forwarding up to 100m. We will see if it does it as promised. I found one problem. It's powered by a 6V/0.3A power supply. I need to find a way to generate that power on-board.

There will surly be a way... :)

Amir Guindehi's Blog

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