Video Motion Amplification

Wow, this is one of those tools that once you start using it, you wonder how you ever got along without it...an amazing leap forward in troubleshooting....and pretty scary what you can't see just walking around looking...

Really interesting! Unfortunately, with my hearing limitations, it is too difficult to understand those two guys talking with the machinery running in the background, so I didn't view the entire video.

Also, I have the impression that, in their side-by-side videos, at least some of the "standard video" images were in fact stills, so not quite a fair comparison.

Click on the cc button at the bottom to the right, which stands for closed caption, it prints out the dialog in the video...the text is generated by speech-to-text app, so sometimes there are some problems with accent and other things...

I gotta confess that I didn't think of that! Will do.

For anyone interested, this explains how it's done. In addition to vibration monitoring, other uses include remote medical monitoring such as pulse rate and breathing.

http://people.csail.mit.edu/mrub/papers/vidmag.pdf

https://www.youtube.com/watch?v=ONZcjs1Pjmk

This TED talk also explains it very well:

https://www.ted.com/talks/michael_rubinstein_see_invisible_motion_hear_silent_sounds?language=en#t-198687

This technology has been used for baby monitors to view movement and heartbeat activity at an exaggerated level.

So that the parents can see the baby is alive and moving at a glance.

Using it to amplify motion of equipment was probably found by a parent who noticed the seemingly stable crib rocking and rolling all night.

You always hear statistics on how much buildings are waving in the wind.

I would like to use this equipment to confirm that they are waving at all.

I remember people saying the Sears tower would move about seven feet which seems crazy to me.

Then again the SR-71 Blackbird leaks when it's on the ground so heck. anything's possible.

The expansion and contraction of pipe always seems of interest to me, it's usually ignored when installing, but can have some rather surprising results...when troubleshooting a piping failure it's something to keep in mind....

https://www.youtube.com/watch?v=szp0DAsCdJQ

Three Science Fair Caliber Demos

One demo might feature a bimetallic biplastic strip thermostat coil for a super graphic version of the old style thermostats with visible movement with only minor temperature changes. The student could use two PVC and two PE flat spiral pipe pairs to form the biplastic layers and weave the two flat spirals together with cheap fishing monofilament to hold them in precise relationships to each other. The specific path of the monofilament could provide appropriate tolerance to accommodate the expected difference in linear expansion between PVC and PE. Suspension of the four pipe assembly from a support with more fishing monofilament could minimize any potential friction between the flat coil assembly and the environment to allow free movement of some indicator arrow to a temperature scale. With all these design features and with the significant expansion delta between the two plastics, a fractional degree scale is likely possible. The configuration of the tension elements would provide a lot of design latitude for the precision and dynamic range of the biplastic thermostat implementation. A huge decision is whether and where to rigidly attach any part of the biplastic strip for zeroing and calibration of the scale. Using the thermostat to control the precise temperature of fluids(eg. air or water) flowing through the pipes could be a part of the design. Choices of how to flow the fluids (serial, parallel, PVC first, PE first,...) could impact the behavior of the control system.

A second display which might implement some heat engine oscillator based on water mist cooling driven by changing air pressure in simple, string suspended PE pipes would be a good way to talk about 500 kilocal/liter heat of vaporization of water. The demo might use some visible check valves, perhaps some super graphic toggle latch, and talk about hysteresis.

PE "thermal muscles" could be used to build a plotter which could be controlled by the temperature of the pipes. An Arecibo style moving pen holder could be actuated by thermal control of the lengths of the pipes extending down to the "focus." Resistors strung through PE pipes could control the temperature within each pipe independently. The resistors would need to smoothly accommodate pipe movement and therefore should not catch on the inside of the pipe as the pipe extends or contracts. This plotter would move rather slowly so any pen used to draw with it should be one not prone to bleed excessively if left in one spot on the paper too long.

Details and specifics of these three kernel ideas are left as an exercise for the student. Video motion amplification could be combined with these for extra credit.

_______________

thewildotter

Excellent ideas! I'm afraid I'd need a sketch to truly follow what you are describing in Demo One. If I understand what you mean by a "flat spiral pipe pair", the centers of the two pipes will be separate by one pipe diameter. A greater change in curvature will result if the separation is less, so instead of pipe, I'd suggest flat plastic strips, the thinner the better, within reason.

In any metropolitan area, there will be at least one plastics store, and they will have scraps of several kinds of plastic. An enterprising middle- or High-school student could probably obtain enough scraps for free to build a bi-plastic strip long enough.

Concepts Are Often Stereotyped and Limited by Drawing Incidentals

Vanishingly small interest in becoming a CAD guy here. I find actual drawings of concepts too confining. People lock on to scale and other details irrelevant to the concept. I prefer to let others discover and dance with those devils in the details. Here is a little ASCII art of the four pipe spiral bundle as a pathetic substitute:

V-PVC V for polyvinyl chloride pipe end on.

E-PE E for polyethylene pipe end on.

In cross section you have two flat spirals implemented with two vertical pipes of the same type of material.

VE gap VE gap VE gap VE gap VE gap VE gap VE gap VE gap VE gap VE gap VE

VE gap VE gap VE gap VE gap VE gap VE gap VE gap VE gap VE gap VE gap VE

Basically, use two matching over-under spiral pipes of PVC to form a flat spiral. Co-wind it with an identical(at some temp) two pipe flat spiral of PE pipe fastened over-under. The four pipe bundle is probably fixed across materials at some single select phase. The vertical pairs of V or E are fastened tightly. The strike through pairs of VE are fastened so that they can slide slightly with respect to each other to accommodate the length inconsistencies from thermal expansions/contractions. It is the watch spring bimetal configuration, simply impemented with plastic pipe just like traditional bimetal thermostat springs. The fact that the flat strips are implemented with pipe is incidental to operation except that the thickness causes some stiffness due to the geometry as opposed to only inherent stiffness of a flat strip. The pipes can be used for heat transfer from an internal fluid to the pipe if one desires that operation. This becomes complicated because of thermal gradients down the pipes due to heat transfer from the fluids inside the pipe, through the pipes, to the fluids outside the pipes. The flow rate of fluids in the pipes would produce a gradient of temperatures down the pipe.

An alternative configuration would be to use concentric V and E pipes and get a plunger(bicycle brake caliper cable) action at one end. Spiraling such a cable would likely introduce excessive friction into its operation so this would likely be a straight run and would probably operate best hanging vertically with the action at the bottom.

Non-pipe (perhaps rods or strands or beams) variations such as weed wacker or 3D printer material could also present interesting design opportunities perhaps at minimal costs.

______________

thewildotter

P.S. Note that my pathetic ASCII art does not commit itself to choosing V or E for the inner or outer material spiral. Just sayin. I guess my software background inclines me to want data hiding in my mental subroutines.

https://nordiclifescience.org/knitting-weaving-artificial-muscles/

Different people's minds work different ways! For me, words are a very poor way of communicating structure. After reading your descriptions several times, I think this is what you are attempting to describe:

Green and blue, of course represent PVC and PE, and grey represents pins of some kind (could be nails). This is showing roughly 4.5 feet (each) of 1/2" pipe , with pins spaced about 6" apart. I'm assuming the pairs of like material would be simply cemented to each other. In fact, if there is a cement that works on both PVC and PE (I've never worked with PE), then the entire assembly could simply be cemented together, with no pins required.

I don't understand why you chose to use 4 pipes, when one of each material will curve exactly the same way.

There is nothing magic about a spiral, beyond making the assembly fit in a smaller space. It would be extremely difficult for anyone not having special equipment to create two mating spirals. Two straight pieces of different pipe materials attached to each other would curve with changes in temperature, and be vastly easier to fabricate.

Beautiful CAD Work !

First, your graphics are attractive and are a possible accurate instantiation of an example of what I was describing.

I agree that words are a poor way of communicating a specific structure. I was doing my best to communicate a genre of structures any one of which might approximate a bimetallic thermostat coil. You chose to use pins and mused about glue. Those are two alternative configurations. I talked about string to allow the latitude of movement between the various pipes to be customized as the designer might wish. For example, you could use string to minimize movement between PVC and PVC and also between PE and PE but between PVC and PE allow considerable relative movement. You might allow even more movement between a supporting rigid frame of minimal thermal expansion and the entire spiral in any but the Z direction. The origin of the expanding lengths might be at one end or the other of the spiral to provide a zeroing with respect to the scale which might appear on the rigid support frame. I did not want to communicate these specifics because they represent customizable design features. That latitude is where a student can demonstrate their understanding and cleverness in using the "physical thermal expansion difference between different materials" phenomenon to innovate a demo device with various useful features. Your cement or your pins might easily produce a device which destroys itself or deforms in undesirable ways such as getting mouth-like gaps between the different materials at the midpoints between pins. OTOH, with limitations on the thermal dynamic range of the device they might be fine.

Four pipes approximates the edges of two thin strips of homogeneous material where the centers of the pipes approximate the two edges of each thin strip. This minimizes vertical squirm that you might get with just one PVC and one PE pipe. I had considered describing many pipes aligned vertically of the same material type but I felt that it was just an incremental refinement of the approximation of a thin strip of homogeneous material which was adequately represented by two pipes of each material defining the two virtual edges of each thin strip. A second red herring avoided by using just two pipes of each material is a cost objection to too many pipes.

The magic of a spiral beyond fitting into a smaller space is that it can be made to look a lot like the thing people see when they disassemble a traditional thermostat. To address ease of construction: PE pipe often comes in spirals when you buy it in big box stores. Rigid straight sections of PVC pipe can be heated and wrapped, once softened, around itself so that when it cools, it retains the spiral shape . There are lots of YouTube videos showing how to make custom angle bends in PVC conduit and how to bell out the ends of PVC pipe to make joints without F/F couplers. I mentioned the straight pipe option in the bike caliper cable description.

I would like to thank you for considering my suggestions. I would like to thank you very much for the amazingly attractive graphic. I know slogging through vague verbal descriptions is not very pleasant, yet you were interested enough to exert that effort. I wrote that stuff just in case someone wanted to have something to inspire some student to innovate. I was trying to be careful to provide as much design latitude as I could without just handing over some specific design. I do not know if there are any parents or teachers lurking who can use this to tickle the creative juices of some STEM student but I had the thoughts and this forum with this thread seemed a reasonable place to enshrine them until someone appropriately motivated came along. The demos actually are intended to move easily and far enough to not require Video Motion Amplification to perceive, so in a sense, they are the classical way to do what Video Motion Amplification does without actually needing the VMA.

_____________

thewildotter

Thanks. It did turn out to be more of a challenge than I originally anticipated, but once I started, I had to finish. FWIW, the 'spirals' aren't true spirals; they are a series of 90° arcs, each one larger than the previous by the same amount.

I taught physics and related subjects for 32 years, before 'retiring' into my second engineering career. While teaching, I had two hand-held bimetallic demonstrators. Each had a bimetallic strip around 10 inches long and a half inch wide, with a wooden handle on one end. One of them was made with two strips of metal (I believe steel and brass) each about 0.05" thick, and riveted together every couple of inches. The other had similar strips, but the strips were only around 0.006" thick, and they were directly bonded to each other, or possibly one metal plated onto the other.

They were initially straight; if you held them in a Bunsen burner, they would curve. The thicker one would curve into an arc of 10 or 15°. Of course the thinner one would heat up faster, but mostly due to being so thin, the thin one could easily be made to curve into a full 180° arc.

I just did some computer graphics to verify: the amount of curvature created by a given temperature difference (and thus the visibility to an untrained observer) is inversely proportional to the separation of the centerlines of the two strips. Thus, if a structure made of 2-1" OD rods or pipes bent a distance of 0.1" for a certain temperature difference, a similar structure made of rods, tubes, or strips of the same materials only 0.1" in OD or thickness would bend a full inch.

That's why I suggested getting flat strips of plastic scraps, rather than pipe. Let's hope some teacher reads this, and suggests some student make one or more. They'd be welcome to contact me for more info.

Finally, the curvature will be greatest when the coefficients of expansion have the greatest difference, so the best demonstration would be of a PE strip bonded to a Stainless steel strip.

Objective Analysis Starts with "What Objective?" Teach Being Willing to Think

"more of a challenge than I originally anticipated" Yep. Every time I start doing CAD things that seems to be the case. Also, I have trouble ever being completely satisfied with the result so it becomes an infinite hole for my time because I want to make this one last improvement.

"taught physics" I suspected as much since you clearly have the Feynmann-esque prerequisite "intuitive grasp" of most natural mechanisms which is generally missing in the general population and even weak in most engineers. Sadly, "intuitive grasp" seems to me to be diminishing due to cultural bias against being willing to think or at least being averse to being perceived as willing to think. This aversion seems to have become highly popular in our institutions of public education at every level which basically renders them pointless. There are refreshing exceptions but it appears that the patient is snake bit, necrotic, and unresponsive.

"visibility... inversely proportional to the separation of the centerlines" ... There is that intuitive grasp of mechanism. You probably also understand that dramatic movement such as this is likely to lead to early failure since it is, at its essence, severe local deformation of the strips. The thinness of the strips is important for tolerating the deformation and you rightly point out that tube geometry has a stiffness which will resist deformation due directly to that stiffness relative to a thin strip. I thought about recommending sheeting or siding but most such commodities have asymmetry which would result in Z direction excursions so I elected to sacrifice centerline distance for symmetry and manufactured uniformity. With the string attachment scheme to allow progressive relative displacement down the spiral and long pieces of cheap, uniform material one can distribute the deformation over the entire length of the spiral and stress the materials less but still find great movement at the end of the assembly opposite the single attachment point. This works best when the temperature is applied to the entire assembly rather than at a single point but it is probably prudent not to be applying a point flame to plastic anyway. The accumulated displacement can optionally be emphasized at the end of a spiral with leverage on an indicator pointer hinged at each terminus of the two materials for visible movement.

I like these potential variations(like the hinged pointer) so that multiple students given the same general task can personalize their solutions. Then they can analyze their personalized variations to see what trade-offs were available and demonstrate their "intuitive grasp" of how to optimize what is important to them. Some may care about how similar their demo is to the commodity thermostat guts. Others may care how much dynamic range, precision, or accuracy they achieve. Others may care how much their demo moves to attract attention. Their advisors can guide them to pinpoint these advantages and what they may be sacrificing to achieve them. Quantifying the tradeoffs can be a good challenge for the most advanced students. Hyping their chosen advantage can be rewarding for those students who may not have a high enough aptitude for quantification. Both are valuable skills and students watching their rivals are motivated to overcome their weaker skillset deficiencies. A mentor with techo-tools like Video Motion Amplification can take quantification and analysis to another level for all the participants and gain higher than usual attention since the tools can rank the efforts. Disparity here can be presented as diversity and flip from having a negative halo to having a positive one. Objective measurement can minimize impact of perceived teacher bias especially if the teacher has good diplomatic skills. This, of course, should be what teachers are all about: demonstrating mechanism and objective comparative analysis.

I seem to be preaching to the choir here. Although, I would recommend thinking about PE/SS being "best".... For what?... greatest movement(dynamic range), useful lifespan, fast response, shiny attention grabber, high repeatability, precision, accuracy, video motion amplification demonstration, cheap purchase, easy to build, teaching the "too cool to learn", mechanism understanding, ...

______________

thewildotter

Corner Mirror Retroreflectors

Your bimetallic strip video showed an "also viewed" retroreflector video which was quite nice. If the metallic coatings on your bubble pack were to be intentionally formed to incorporate lots of corner reflector embossed dents then a lot of the radiant energy would return to its source. Since the metallic coatings are first surface mirrors they would not suffer from absorption by bulk transparent material in the direction opposite the bubbles. This retroreflector would have the advantages of retroreflectors that I have previously posted about. For example, if a house with this retroreflector were beside neighboring houses, the heat reflected would return to its source more than impacting any nearby house. Returning to, say, the direction of the sun would minimize local warming and ultimately global warming. It constitutes low hanging fruit for an actually effective strategy to impact climate as opposed to most others which almost all end up mostly heating the earth despite the intentions.

It, of course, does not eliminate all bad effects such as greenhouse phenomena where lowered frequency of radiation has a harder time exiting the atmosphere but simple reflection of frequencies that made it to the radiant barrier have a better chance of making it back out since those frequencies made it in. If, instead, the heat had been absorbed by a surface, it would most likely be reradiated at lower frequencies which would have a harder time escaping the atmosphere.

____________

thewildotter