Timescapes - Digital Timelapse Discussion
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DIY - Stabilising Gimbal and Timelapse pan/tilt in one unit?
http://forum.timescapes.org/phpBB3/viewtopic.php?f=24&t=12521
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Author:  cbkernow [ Mon Jan 19, 2015 2:49 am ]
Post subject:  DIY - Stabilising Gimbal and Timelapse pan/tilt in one unit?

I'm looking to create a useful Raspberry Pi based pan tilt mechanism for my own use in timelapse and panoramic photography. (Eventually I will also incorporate horizonatl movement along my slider)

It occurs to me that a simple pan tilt mechanism is very similar to a gimbal based video stabilisation platform.

A potential problem though: is the hardware (stepper motor or brushless motor) suitable for both applications?

Do you forsee that choosing the best motor for a precise slow pan/tilt mechanism is totally wrong for a real time reactive gimbal? (and of course vise versa)

Just curious to hear your thoughts on this?

My number one aim is the pan tilt so rather than compromise to do both, I'll stick with the best for that application.

Author:  wsp35 [ Mon Jan 19, 2015 8:25 am ]
Post subject:  Re: DIY - Stabilising Gimbal and Timelapse pan/tilt in one u

I would say it is not possible.

Stepper motors are too slow for stabilisation.

Brush less motors are too inaccurate for motion control.

Maybe a brushless motor with an incredibly accurate encoder geared down a little may work, but you aren't going to be able to DIY that realistically.

S

Author:  sciencelookers [ Tue Jan 20, 2015 7:01 am ]
Post subject:  Re: DIY - Stabilising Gimbal and Timelapse pan/tilt in one u

I wouldn't say the stabilizer part is impossible, just that its probably going to get interesting before its done. If it works well and is affordable, I'd buy one. Would be cool to try hyperlapse without the tripod, also if it actually stabilizes hand held shots so they don't need stabilization in post, would be great.

The worst part of making pan-tilt heads is the requirement for zero backlash. There have been several threads about this on the forum over the years, and a lot of good information is available if you look them up.

The gist of it is that wind can make the head wobble within the range of the backlash. Easiest way to fix that is not having such good bearings or have a little friction brake, so the brake prevents wind from moving the head but the motor overpowers the brake when you want it to move. Tilt has a problem as unbalanced loads go past the tipping point. Again you see a bump as it moves within the backlash. Backlash is the gap between gear teeth which is necessary to prevent them from locking up.

eMotimo uses the brake method. Expensive heads use harmonic drive or other special gear reducers which do not have backlash, but those are expensive gear reducers and are really difficult to make yourself.

Good luck!

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