Position/velocity

[crwper]

I'm looking for a way to measure accurately my position and velocity on static line jumps. GPS won't cut it, because of the positional accuracy and time sampling required.

I've been thinking about using an aircraft inertial navigation package hooked up to a data logger, but at this point I'm mainly exploring my options.

My goal here is to understand the performance envelope of my canopy as well as possible, particularly opening altitude and velocity changes immediately after opening, and variations in both parameters, using several deployment methods in various environmental conditions. This is a long-term project.

Let me know if you have any ideas!

Michael

[imported_Tom Aiello]

I heard that at one point during the Petronas thing last year, they had cooked up a scheme to measure position and velocity with lasers (for their tracking competition). I think they canned it before the actual event, but maybe someone involved with the initial setup did some of that research already. Anyone know?

If you answer this, please leave out any political diatribe about who ran it, who got left out, etc. We're just looking for technical info, here.

Another idea that I used a while back is to fix cameras in multiple locations, then synchronize the playback to triangulate positions. I did this by trailing a rope with obvious markings off the object, behind the test deployment, and fixing the camera in front of the deployment. To get a real fix, you'd obviously have to create some kind of "measuring sticks" in three dimensions (I thought about painting marks down the side of a concrete pillar on a local 60' span, as I was really only testing deployment, not canopy flight).

I'd love to see the data you come up with, though.

--Tom Aiello
tbaiello@mac.com

[guest]

I know you can do it with sharks with FRICKIN LASER BEAMS on their head.

[guest]

...Your friends are right...you DO need to get out more...:P

[guest]

You are more right than you know

[guest]

Huh, no laser range detecting system was ever seen/used/talked about at that event. Infact it became obvious that focus on a strong push was gonna get you further out than any track could from an object that was essentially about 260m to impact.

I think one judge was playing with same kind of eyeballing it device, most crude ,so it was all scrapped in the end, especially after day 1 which was carnage.

/Lukas

[guest]

Check this out. Dan Preston at Atair has some pretty cool toys that may be helpful for your project. Some of the stuff looks pretty expensive, though.

http://www.extremefly.com/aerospace/...igh-speed.html

http://www.extremefly.com/aerospace/...yperbolic.html

http://www.extremefly.com/aerospace/.../DAS/SDAS.html

[guest]

Yes this site is awesome. His shark head laser mount is really clean looking. Also hie meat helmets are awesome. Good BASE site

[d-dog]

. . . and ill-tempered sea bass?

[460]

Acoustical sensor units.

We used them in high energy nuclear physics experiments to survey magnetic fields. As many as 20 receivers called buttons can be used with an accuracy of +- 1mm, sampling up to 200 times per second when using a single button, and at 10 times per second with 20 buttons.

I'll have to search it down again but I too was interested in putting various position measurement devices on my canopy to measure flight characteristics. I never got around to it. Search the web under:
acoustical sensor and magnetic field and (either)
lawrence berkeley or lawrence livermore.

-Chris

[crwper]

Any idea what the range is?

Michael

[crwper]

This could work at some sites... Thanks!

Michael

[460]

Not that great. Probably a radial range of 40 to 50 feet, relying on ultrasound. Perhaps more if the ultrasound emitter can be turned up.

[guest]

If you want to do this cheaply why not just get a couple of camera's, one a fair distance from the object looking directly at it from as parallel a position as possible, with the shot containing the whole object from base to exit point, and one at the exit point looking straight down, video the jumps from these points and you can work out your position pretty accurately from pausing the video frames using trigonometry equasions that you'll find in a high school maths textbook. I haven't tried it but it will work as long as the initial measurements are right.

And before anyone else gets to it, I know I need to get out more too.

[guest]

I have seen in use a laser system that automatically tracks a mirrored target and measures to the thousandth of an inch. The XYZ coordinates can be imported into a CAD package. I think there are systems out there fully capable of what you describe, except they may not be set up to record the time coordinate.