Camera vibrations

https://www.google.com/#q=gopro+iso+vibration+damping

why are you using a camera ?

James wrote:
I bought a Mobius miniature camera to fit to my handlebars.

https://www.mobius-actioncam.com/

Image quality is great. It's small and light. Didn't cost a bundle.

I've read about vibration damping and so on, as I see when I go over
bumpy road I get the jello effect through the video.

I came across another bicycle vibration analysis study today
http://mecano.gme.usherb.ca/~jmdrouet/velus/assets/0707cham.pdf and
one part caught my eye.

Frequency 27.8Hz Front-to-back motion of fork.


This got me to thinking. The jello effect is a rippling through the
picture at a few Hz. Could this be a beat frequency between the shutter
speed (30Hz), and the front wheel moving back and forth as it rides over
bumps?

Further to this, if the camera simply moved up and down a small amount,
but continued to aim approximately in the same direction, I don't think
there would be such a big effect on the video. I think to cause the
jello effect the camera is being aimed slightly higher and lower than
the average position, at near 30Hz. That is the camera has changing
pitch, not just raised and lowered.

So I wonder how much bending is transferred through the fork steerer, on
to the head stem and through to the bars?

My next test will be to (temporarily) mount the camera in the middle of
the head tube. There may be some pitch change as the front wheel rides
over a bump and a little later the back wheel follows, but I wouldn't
have thought the bike would pitch at 30Hz.

Thoughts?


It is a build in feature to make it all look more dramatic :-). I have a
Garmin Virb to make little clips from club rides, mostly off road. The
camera has some kind of anti vibration mode but I see little difference
with or without. Still I am impressed with the image quality despite the
bumpy rides on a unsuspended crossbike off road.

--
Lou

On 12/7/2015 3:17 PM, James wrote:
On 08/12/15 02:29, Frank Krygowski wrote:
On 12/7/2015 12:56 AM, James wrote:
I bought a Mobius miniature camera to fit to my handlebars.

https://www.mobius-actioncam.com/

Image quality is great. It's small and light. Didn't cost a bundle.

I've read about vibration damping and so on, as I see when I go over
bumpy road I get the jello effect through the video.

I came across another bicycle vibration analysis study today
http://mecano.gme.usherb.ca/~jmdrouet/velus/assets/0707cham.pdf and
one part caught my eye.

Frequency 27.8Hz Front-to-back motion of fork.


This got me to thinking. The jello effect is a rippling through the
picture at a few Hz. Could this be a beat frequency between the shutter
speed (30Hz), and the front wheel moving back and forth as it rides over
bumps?

Further to this, if the camera simply moved up and down a small amount,
but continued to aim approximately in the same direction, I don't think
there would be such a big effect on the video. I think to cause the
jello effect the camera is being aimed slightly higher and lower than
the average position, at near 30Hz. That is the camera has changing
pitch, not just raised and lowered.

So I wonder how much bending is transferred through the fork steerer, on
to the head stem and through to the bars?

My next test will be to (temporarily) mount the camera in the middle of
the head tube. There may be some pitch change as the front wheel rides
over a bump and a little later the back wheel follows, but I wouldn't
have thought the bike would pitch at 30Hz.

Thoughts?

Interesting. I hadn't heard of the Jello Effect. I guess this is a
good example: https://vimeo.com/69906288

The beat frequency idea seems possible to me.

If the effect is dependent on changes in pitch, I wonder if it could be
prevented by a parallelogram linkage like this:
http://www.atticpaper.com/prodimages...banner1897.jpg
Its intent is to provide vibration isolation without pitch change.



Hmm.. I can understand how the parallelogram may act as a vertical
motion suspension arm, but I do not see how it aims the lamp straight
while the handlebars pitch (rotate to aim higher and lower).

Ah. OK, I see what you're saying.

If the flex of the stem and bars is the real culprit, it might be better
to mount the camera elsewhere on the bike - say, to the head tube.
Nothing is rigid, of course, but I'd expect very little
vibration-induced pitching motion there - just lots of vibration, which
you'll have anywhere. Perhaps the parallelogram would do the job in that
location.

If you must have a handlebar mount and the handlebars and/or stem are
changing the pitch, you might have a chance with a modified
not-quite-parallelogram configuration. That parallelogram is what we
MEs call a four bar linkage, with (in this case) the rear or fixed base
being one bar. If the front vertical bar is shorter than the base bar,
then a downward motion would tend to tilt the camera upward. I suppose
it might be possible to choose the spring constant, mass, and dimensions
so the linkage compensates for the bar's downward tilt.

Sounds tricky, though.
--
- Frank Krygowski

On Tue, 8 Dec 2015 06:07:33 +1000, James
wrote:

On 07/12/15 21:01, John B. wrote:
On Mon, 7 Dec 2015 15:56:14 +1000, James
wrote:

I bought a Mobius miniature camera to fit to my handlebars.

https://www.mobius-actioncam.com/

Image quality is great. It's small and light. Didn't cost a bundle.

I've read about vibration damping and so on, as I see when I go over
bumpy road I get the jello effect through the video.

I came across another bicycle vibration analysis study today
http://mecano.gme.usherb.ca/~jmdrouet/velus/assets/0707cham.pdf and
one part caught my eye.

Frequency 27.8Hz Front-to-back motion of fork.


This got me to thinking. The jello effect is a rippling through the
picture at a few Hz. Could this be a beat frequency between the shutter
speed (30Hz), and the front wheel moving back and forth as it rides over
bumps?

Further to this, if the camera simply moved up and down a small amount,
but continued to aim approximately in the same direction, I don't think
there would be such a big effect on the video. I think to cause the
jello effect the camera is being aimed slightly higher and lower than
the average position, at near 30Hz. That is the camera has changing
pitch, not just raised and lowered.

So I wonder how much bending is transferred through the fork steerer, on
to the head stem and through to the bars?

My next test will be to (temporarily) mount the camera in the middle of
the head tube. There may be some pitch change as the front wheel rides
over a bump and a little later the back wheel follows, but I wouldn't
have thought the bike would pitch at 30Hz.

Thoughts?

From your description and some photography that I've done I suspect
that the camera is moving, however little.

That part is obvious. The question is whether it is simple up and down
movement, or changing pitch, which is worse and how to reduce.

My experience, with film
cameras, is that they sometimes can be isolated from the vehicle to
eliminate high frequency vibration but not actual movement, or perhaps
I should use the term "gross movement" as vibration is, effectively,
movement.

I would wonder what would happen if you mounted the camera on your
helmet (or hat :-)?

Helmet, shoulder or chest mount apparently works, however the first is
possibly illegal in Australia as it may affect the helmet crash
worthiness - low as it is - and I don't care to wear a camera at all.
It has to be bike mounted AFAIAC.

If a mounting other then solidly on the bike seems to solve part or
all of the problem then you have eliminated what you call "vibration",
actually high speed and low amplitude movement. The next step would be
to build/buy some sort of mount that has the properties of damping
vibration. See below for examples:

http://www.helipal.com/lp-0064-jello...ount-base.html

http://flitetest.com/articles/_Vibra...e_Camera_Mount

http://petapixel.com/2014/07/29/buil...rone-mount-10/
--
cheers,

John B.

On 08/12/15 10:27, John B. wrote:
On Tue, 8 Dec 2015 06:07:33 +1000, James
wrote:

On 07/12/15 21:01, John B. wrote:
On Mon, 7 Dec 2015 15:56:14 +1000, James
wrote:

I bought a Mobius miniature camera to fit to my handlebars.

https://www.mobius-actioncam.com/

Image quality is great. It's small and light. Didn't cost a bundle.

I've read about vibration damping and so on, as I see when I go over
bumpy road I get the jello effect through the video.

I came across another bicycle vibration analysis study today
http://mecano.gme.usherb.ca/~jmdrouet/velus/assets/0707cham.pdf and
one part caught my eye.

Frequency 27.8Hz Front-to-back motion of fork.


This got me to thinking. The jello effect is a rippling through the
picture at a few Hz. Could this be a beat frequency between the shutter
speed (30Hz), and the front wheel moving back and forth as it rides over
bumps?

Further to this, if the camera simply moved up and down a small amount,
but continued to aim approximately in the same direction, I don't think
there would be such a big effect on the video. I think to cause the
jello effect the camera is being aimed slightly higher and lower than
the average position, at near 30Hz. That is the camera has changing
pitch, not just raised and lowered.

So I wonder how much bending is transferred through the fork steerer, on
to the head stem and through to the bars?

My next test will be to (temporarily) mount the camera in the middle of
the head tube. There may be some pitch change as the front wheel rides
over a bump and a little later the back wheel follows, but I wouldn't
have thought the bike would pitch at 30Hz.

Thoughts?

From your description and some photography that I've done I suspect
that the camera is moving, however little.

That part is obvious. The question is whether it is simple up and down
movement, or changing pitch, which is worse and how to reduce.

My experience, with film
cameras, is that they sometimes can be isolated from the vehicle to
eliminate high frequency vibration but not actual movement, or perhaps
I should use the term "gross movement" as vibration is, effectively,
movement.

I would wonder what would happen if you mounted the camera on your
helmet (or hat :-)?

Helmet, shoulder or chest mount apparently works, however the first is
possibly illegal in Australia as it may affect the helmet crash
worthiness - low as it is - and I don't care to wear a camera at all.
It has to be bike mounted AFAIAC.

If a mounting other then solidly on the bike seems to solve part or
all of the problem then you have eliminated what you call "vibration",
actually high speed and low amplitude movement. The next step would be
to build/buy some sort of mount that has the properties of damping
vibration. See below for examples:

http://www.helipal.com/lp-0064-jello...ount-base.html

http://flitetest.com/articles/_Vibra...e_Camera_Mount

http://petapixel.com/2014/07/29/buil...rone-mount-10/

Yep. I have looked at such things. I made something similar using an
aluminium sheet, some foam and a strip inner tube. My camera mount has
slots that I can feed the inner tube strip through, and this holds the
camera down on a couple of pieces of foam that sit between the camera
and the aluminium plate, that is cable tied to the supplied handlebar
mount platform.

It certainly reduces some vibration, but all these ideas are for a
quad-copter or similar, that probably has vibration amplitudes far lower
than a bicycle handlebar being ridden over rough chip seal.

My current thought is to produce an arm about 50-75mm long to mount the
camera on, and pivot the arm using an elastomer bush (maybe silicon
rubber) from a rigid handlebar clamp. The difficulty will be to get a
low enough spring constant and high enough damping so that the natural
frequency of the mass/arm/elastomer bush is around 10Hz or lower I
guess, and over damped.

I'm not keen on attaching it to the head tube if I can help it, but that
might be the next step.

--
JS

minimalist device. Instaled an Audio vox forwardview vehicle loop recoder, same price similar size. The van does not vibrate with acceleration/distance/frequency of a chip sealed bicycle.

See: iso vibration
utube: Mobius software

Google Images has charts for: iso vibration

Within the cost design package seems no way the Mobius would image on a chip seal bicycle frame.

only a Mobius forum or Mobius hisself could focus the application

rOn Tue, 8 Dec 2015 12:16:35 +1000, James
wrote:

On 08/12/15 10:27, John B. wrote:
On Tue, 8 Dec 2015 06:07:33 +1000, James
wrote:

On 07/12/15 21:01, John B. wrote:
On Mon, 7 Dec 2015 15:56:14 +1000, James
wrote:

I bought a Mobius miniature camera to fit to my handlebars.

https://www.mobius-actioncam.com/

Image quality is great. It's small and light. Didn't cost a bundle.

I've read about vibration damping and so on, as I see when I go over
bumpy road I get the jello effect through the video.

I came across another bicycle vibration analysis study today
http://mecano.gme.usherb.ca/~jmdrouet/velus/assets/0707cham.pdf and
one part caught my eye.

Frequency 27.8Hz Front-to-back motion of fork.


This got me to thinking. The jello effect is a rippling through the
picture at a few Hz. Could this be a beat frequency between the shutter
speed (30Hz), and the front wheel moving back and forth as it rides over
bumps?

Further to this, if the camera simply moved up and down a small amount,
but continued to aim approximately in the same direction, I don't think
there would be such a big effect on the video. I think to cause the
jello effect the camera is being aimed slightly higher and lower than
the average position, at near 30Hz. That is the camera has changing
pitch, not just raised and lowered.

So I wonder how much bending is transferred through the fork steerer, on
to the head stem and through to the bars?

My next test will be to (temporarily) mount the camera in the middle of
the head tube. There may be some pitch change as the front wheel rides
over a bump and a little later the back wheel follows, but I wouldn't
have thought the bike would pitch at 30Hz.

Thoughts?

From your description and some photography that I've done I suspect
that the camera is moving, however little.

That part is obvious. The question is whether it is simple up and down
movement, or changing pitch, which is worse and how to reduce.

My experience, with film
cameras, is that they sometimes can be isolated from the vehicle to
eliminate high frequency vibration but not actual movement, or perhaps
I should use the term "gross movement" as vibration is, effectively,
movement.

I would wonder what would happen if you mounted the camera on your
helmet (or hat :-)?

Helmet, shoulder or chest mount apparently works, however the first is
possibly illegal in Australia as it may affect the helmet crash
worthiness - low as it is - and I don't care to wear a camera at all.
It has to be bike mounted AFAIAC.

If a mounting other then solidly on the bike seems to solve part or
all of the problem then you have eliminated what you call "vibration",
actually high speed and low amplitude movement. The next step would be
to build/buy some sort of mount that has the properties of damping
vibration. See below for examples:

http://www.helipal.com/lp-0064-jello...ount-base.html

http://flitetest.com/articles/_Vibra...e_Camera_Mount

http://petapixel.com/2014/07/29/buil...rone-mount-10/

Yep. I have looked at such things. I made something similar using an
aluminium sheet, some foam and a strip inner tube. My camera mount has
slots that I can feed the inner tube strip through, and this holds the
camera down on a couple of pieces of foam that sit between the camera
and the aluminium plate, that is cable tied to the supplied handlebar
mount platform.

It certainly reduces some vibration, but all these ideas are for a
quad-copter or similar, that probably has vibration amplitudes far lower
than a bicycle handlebar being ridden over rough chip seal.

My current thought is to produce an arm about 50-75mm long to mount the
camera on, and pivot the arm using an elastomer bush (maybe silicon
rubber) from a rigid handlebar clamp. The difficulty will be to get a
low enough spring constant and high enough damping so that the natural
frequency of the mass/arm/elastomer bush is around 10Hz or lower I
guess, and over damped.

I'm not keen on attaching it to the head tube if I can help it, but that
might be the next step.

The basic idea - an arm with an elastic pivot is certainly sound but I
think that you are going to have problems with both frequency
dampening and gross movement, the "buzz" from smooth pavement versus
hitting the big bump.

Probably some large, low pressure, say 4 inch, tires would help a lot
:-)

--
cheers,

John B.

It certainly reduces some vibration, but all these ideas are for a
quad-copter or similar, that probably has vibration amplitudes far lower
than a bicycle handlebar being ridden over rough chip seal.

Mount the camera on a quad-copter.
http://reviews.mtbr.com/news-silca-l...-support-drone