You know what, it would be really interesting if I could stream data from the Raspberry Pi camera and process it in real time. It would also be interesting if I could do likewise with HTML 5 Web API. Guess what? You’re in good luck. On the Raspberry Pi, you can get live streams via Video4Linux2. Also, SimpleCV/OpenCV provides a wrapper to process live streams from web cams. Yes, so OpenCV is a good framework for you to work with, it just doesn’t provide the direct implementation of your needed algorithm. As for the HTML 5 Web API, it looks like you can only fetch a video in bulk, not process a live stream in real time. Anyways, that’s what that new media buffer thing is about in Web APIs, it’s to enable that kind of class of applications. Yeah, like a YouTube web page that makes it super easy to upload smartphone videos to YouTube.
20170416/DuckDuckGo raspberry pi process live video data
20170416/https://raspberrypi.stackexchange.com/questions/23182/how-to-stream-video-from-raspberry-pi-camera-and-watch-it-live
- Also covered were some fast and efficient means to stream video over the Internet. Use VLC client with V4L2.
20170416/DuckDuckGo mdn webcam api html 5
20170416/https://www.webcodegeeks.com/html5/html5-web-camera-example/
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Also, there were a lot of very good questions asked in the comments of this artcle. Like building a mobile app, using multiple web cams, etc.
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Note: Truth in advertising. I didn’t get to that web search result so easily. Nope, it took a few tries. These are the earlier attempts.
20170416/DuckDuckGo mdn webcam
20170416/DuckDuckGo mdn webcam api
Also, here are more details on the Raspberry Pi camera hardware and software. Yes, it looks like it is possible to get manual control over the camera settings as you will need for the 3D scanning job. Well, hopefully, because that was one of the problems with the FabScan, that they couldn’t get manual control and fix the parameters.
20170416/https://www.raspberrypi.org/learning/getting-started-with-picamera/
20170416/https://www.raspberrypi.org/documentation/usage/camera/raspicam/raspivid.md
20170416/https://www.raspberrypi.org/documentation/hardware/camera/README.md
So, about the 3D scanner place mat design. Yeah, the crane. I’m probably going to have to build it out of wood in order to get good structural strength for the range of objects that I might consider hanging. Given the amount of space the crane and back board allows for, some objects that fit in that space might be somewhat heavy and not free-standing.
So, yes, I can build the setup myself, but can I find a setup that is already commercially manufactured? Yeah, like a “desktop crane.” Well, er, the results were hard to find, and oh no! I don’t want a $5000 crane truck! Okay, so changing my search terms to “toy crane,” but then I fear that it appears that many designs are over-complicated, designed more for the sake of intellectual curiosity and entertainment than for practical use.
Okay, fine, so that means that I’ll be building my own in order to get a reasonably simple setup.
20170416/DuckDuckGo small crane armature
20170416/DuckDuckGo small desktop crane armature
20170416/DuckDuckGo desktop mini crane
20170416/https://www.alibaba.com/product-detail/Desktop-Crane_100305812.html
20170416/DuckDuckGo toy crane
20170416/http://www.instructables.com/id/Kid-Crane-Riding-Toy/
3D scanning notes. 3D scanner notes.
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Okay, so I have a new 3D scanner design idea. “Laptop and compass design.” It is a fold-up two-paneled paper with a compass turntable on the bottom panel. It takes the least amount of space to operate. Of course, it comes with many disadvantages, namely that you must move the object to scan it from different angles and that it does not provide an armature to support non-free-standing objects. Hence, it is not truly a “non-contact” 3D scanning system. Suffice it to say, it cannot be used to make 3D scans of as large of a range of objects. On the other hand, this design has superior portability for picking up and moving to distant locations.
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The design idea borrows from that of my toy compass design. Well, why not use that to measure actual angles that you rotate an object to on a platform? As a matter of fact, that is a pretty good design idea for a 3D scanner. Certainly it is a much lower cost and more compact design compared to the similar commercial turn-table portable 3D scanner design that I saw presented in the FabScan research paper.
The only problem is that the angle readings must be performed manually. Not if you mark up the compass construction with machine-readable barcodes? Sure, that can work, but the design of the barcode reader will have to be a little more complex to account for the precise rotation of a small number of barcodes. Well, that’s not too much of a problem if I implement the barcode recognition logic in full for my larger place mat design.
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Important! Remember to account for ramp-up time when starting the motor. Make sure you include this in your instructions to the user.
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Use a wind-up spring instead of a motor to rotate the laser at constant angular velocity? Would it be better and cheaper? Cheaper if you use a cheap winding and spring mechanism, but the high quality springs can get rather expensive.
20170418/https://en.wikipedia.org/wiki/Mainspring
20170419/https://en.wikipedia.org/wiki/Clockwork_radio
20170419/https://en.wikipedia.org/wiki/Human_power
It’s interesting that they have an article named “Human power.”
Off topic, but useful general knowledge:
20170418/https://en.wikipedia.org/wiki/Leaf_spring
Wind-up notes. Yeah, there’s the clockwork radio. So is there a such a thing as a wind-up flashlight?
20170419/DuckDuckGo wind up spring flashlight
20170419/http://ask.metafilter.com/104007/Windup-light-that-does-not-use-a-battery-to-store-power
20170419/https://en.wikipedia.org/wiki/Human_power
Yes it does look rather challenging to do well.
20170419/DuckDuckGo micro electric generator
20170419/DuckDuckGo raspberry pi wind up
20170419/https://www.raspberrypi.org/forums/viewtopic.php?f=2&t=4122
Okay, so these MEMs devices are a little bit smaller than my target size.
20170419/https://en.wikipedia.org/wiki/Microelectromechanical_systems
Okay, this is a very good article.
20170419/DuckDuckGo clockwork electric generator module
20170419/http://www.trevorbaylisbrands.com/tbbnew/technology/winduppower.asp
So, the conclusion. Want to power a small hand-held electronic using wind-up power? You’re definitely in good shape for your particular use case. Even though clockwork springs are heavier and store less energy than AA batteries, it turns out that I don’t need nearly the full energy of a AA battery for my application, so the spring energy storage will work just fine.
Never fear, you can turn a DC motor into a generator with ease. So you can go both ways, no need to make up your mind before you get started.
20170419/DuckDuckGo can you use a dc motor module as a generator
20170419/http://www.instructables.com/id/DC-motor-as-a-generator/
Okay, looking for motors that I can wind in reverse to make an electric generator.
Oh, this is a really nice document. Wow, it totally compensates for the lack of information available on Wikipedia in this subject of mechanical engineering. And, the document design is really gaudy. If you look closely, there is a screenshot of a web browser that appears to be Internet Explorer 5.5 running on Microsoft Windows 98. Interesting that they could make such a nice looking document way back then. Then again, mechanical engineering is a pretty old and established engineering profession, so it’s no wonder that there were highly knowledgeable people in the profession. And, being that they were engineers, of course they had access to one of the more powerful Windows 98 computers.
20170419/DuckDuckGo milliwatt motor
20170419/http://www.farnell.com/datasheets/89672.pdf
Okay, so I’ve learned quite some new things from reading this document. First of all, DC motors are designed to have a range of speeds at which they work optimally at. Below those speeds they don’t work so well. Usually, the default speed of the motor is too fast for most applications, so gearing must be used to slow down the motor. But then the motor outputs more torque! Also, what is the minimum energy output of the motor? 12 V input, 3 W output. Oh, yeah, the disadvantages of the system.
So, it looks like the disadvantage of even a DC motor generator is that it may require quite some energy input to get even any energy output.
Here are some more useful resources on DC motors.
20170422/DuckDuckGo low current dc motor
20170422/http://www.designworldonline.com/Selecting-Small-DC-Motors-for-Low-power-Applications/
20170422/https://en.wikipedia.org/wiki/DC_motor
Okay, I think I get the idea. The number of windings determines how much energy you get out of the motor for a particular voltage. As my experiments below show, it’s okay to feed the motor less voltage than the specification indicates. I believe the indicated voltage is the maximum voltage for continuous operation under the specified environmental conditions. So we’re okay, no need for more searching.
Next question.
20170420/DuckDuckGo is it safe to connect an led and a motor to the same power supply
Okay, now I couldn’t really find a real answer, but I guess that it is safe when you think about it. If you can connect a relay and a LED in parallel, then it must be just as safe to do so with a motor, and I’m pretty sure I’ve done that before with the 200 in 1 electronics kit.
“Yes” is the answer. Indeed, I have done an experiment where I power both an LED and turn a motor on and off from the same 3 V power source and I have not had issues. Thus such a mechanism must work just as well in the case of using the laser diode.
So, to put things this way, the inductive spiking problem is only a problem when you need to interface CMOS electronics with motors. Otherwise, you wouldn’t normally expect it to be a problem with most electronics. LEDs and TTL circuitry are okay.
Next question.
About DC motor voltages and power generation. Can a DC motor generate 3 volts with ease? Well, let’s do an experiment. Take that small Lego motor and wire it up to the 200 in 1 electronics kit to 3 volts. Does it work? Yes it does. Now let’s check if we turn it and connect it to our digital multimeter. What voltage do we get? We can easily sustain 3 volts by rotating the motor at a decent speed, but greater voltages can be generated by rotating the motor faster.
Thus, in order for this to work well with our laser, we need current smoothing and voltage regulation circuitry on the output. Perhaps a simple integrated bridge rectifier with a built-in voltage regulator would do the trick.
Yes, now for the question on voltage regulation. Does a switched-mode power supply generate electromagnetic noise? Does a voltage regulator generate less EMF noise than a switched-mode power supply?
Let’s go check Wikipedia. And the answer? Yes, indeed a simple linear voltage regulator generates less EMF noise than a switched-mode power supply. Actually, in fact, for very low voltage applications, the linear voltage regulator can be preferred not just due to implementation simplicity, but also due to superior performance under some circumstances.
20170422/https://en.wikipedia.org/wiki/Voltage_regulator
20170422/https://en.wikipedia.org/wiki/Voltage_regulator#Comparing_linear_versus_switching_regulators
20170422/https://en.wikipedia.org/wiki/Constant_current_regulator
Off topic. Ah, so this is the Wikipedia article on the related computer component.
20170422/https://en.wikipedia.org/wiki/Voltage_regulator_module
Next question.
Where do we buy the wind-up spring module?
20170422/DuckDuckGo wind up gearbox mechanism do it yourself instructables
20170422/http://www.instructables.com/id/Creating-3D-printed-wind-up-no-assembly-required-g/
Interesting, but not what we want. No, we want professional metallurgy in the spring mechanism, not just flexible plastic. But, remember that you can 3D print plastic gears if you don’t think you can get what you need as already manufactured parts.
20170422/DuckDuckGo wind up mainspring module
20170422/DuckDuckGo wind up spring
Ah, yes, looks like we’re making progress.
20170422/http://www.globalspec.com/Industrial-Directory/wind_up_spring
Okay, no, that’s not good enough.
20170422/DuckDuckGo wind up spring supplier
Here is a listing of mostly just bare springs that need to be integrated with additional mechanisms to make a useful spring motor.
20170422/https://www.alibaba.com/showroom/wind-up-spring.html
20170422/https://www.alibaba.com/product-detail/Stainless-steel-wind-up-spring-rewind_60631166549.html?s=p
20170422/DuckDuckGo how to build a wind up toy
This page contains useful information on the internals of wind-up mechanisms.
20170422/http://re.trotoys.com/article/wind-up-mechanics/
20170422/DuckDuckGo spring-powered motor
20170422/https://www.alibaba.com/showroom/spring-powered-motor.html
These are some useful information pages on the different kinds of springs. Unfortunately, these company websites center around custom manufacturing for engineer requests. Yeah, too expensive for my taste. Looking at these, I think it is clear that I just want a conventional power spring made of stainless steel.
- Yes, but I want it built into a packaged enclosure!
20170422/http://www.springcompany.com/products/power-springs
20170422/http://www.hunterspringandreel.com/products/springs
20170422/http://www.hunterspringandreel.com/products/springs/power-spring-clock-spring
20170422/http://www.hunterspringandreel.com/products/springs/power-spring-clock-spring/conventional-power-spring
20170422/http://www.hunterspringandreel.com/products/springs/power-spring-clock-spring/prestressed-power-spring-spirator
20170422/http://www.hunterspringandreel.com/products/springs/constant-force-spring-negator
20170422/alibaba spring powered wind-up motor
20170422/https://www.alibaba.com/showroom/wind-up-spring-motor.html
Lots of good results on Alibaba, but I need to go revisit the pages with a better browser. They might have what I need, but some assembly may be required, unfortunately. Unfortunately it seems that I can’t just get a metal box containing everything I need.
Anyways, about the spring speed. Maybe you don’t need to spin the motor at the full 3 volts speed. Perhaps the “joule thief” circuit can somehow be used to deliver the correct voltage even when the motor spins at a slower speed. This will allow me to use less powerful springs, and it will make the entire system more energy efficient.