The Rotary Torque Sensor… continued

Well, so far, so good. That’s all I can say at the moment. The rotary gage is operational, though it hasn’t had brushes made for it and it seems to output a reasonable amount of voltage difference based on displacement.

Here’s what it looks like so far:

The rotary strain sensor
The rotary strain sensor

I’ve put it through its paces thus far and I can see a 10mV difference when I move the sides, that’s good enough. Soon I’ll see if it works with the stuff attached.

Websites and registration, an opinion.

After a few years of looking on the web for various items, the trend towards mandatory registration on certain websites is becoming more and more prevalent. Now, I’m not talking about social networking sites or the really massive corporations, I’m talking about the mid-size companies that have their IT dude make them a site.

Nowadays if you want to find any kind of information on the product a smaller company makes, you have to register for an account on their site even for things like datasheets. While on the surface this seems like a good idea, since you can engage the person in setting up an account on your site and have their e-mail address for later, it is irritating at best. Unfortunately, companies take it so far as to require you to register for almost every thing under the sun. Things I’ve seen required registration for:

  • Product Pricing
  • Data Sheet
  • Frequently asked questions
  • Their forums (Not to post, just to see their forums)
  • The products they make!?!?!

Like I said, I can see the logic to it in terms of engaging the browser, however, myself I find myself backing out of the page, even if I need the information when presented with a ridiculous registration prompt. I’m fairly certain that other people do the same thing when looking for a product. Especially when looking for parts. There are so many manufacturers of similar parts and when you have to go from site to site and fill in a billion fields of data just to see what they fucking make is absolutely ridiculous!

All I can say is this. STOP REQUESTING REGISTRATION YOU IDIOTS!

In the end they only increase the traffic on their phone lines with engineers and designers that simply want some damned information. Stupid.

Been almost 2 years at Endura

Now that It’s coming up on two years at the place I work, I was looking through some of the drawings. I figured it’d be fun to post some of them. I’ll simply place a gallery here, click the images to see a more detailed description

Note that these aren’t all of my drawings, but a decent selection of them.

Torque Coupling Update

This update is a little bigger than usual since I want keep the images and text as a sort of record of what I did for future reference. For the viscometer project, I’ve discovered that the motor is far too unreliable to produce reliable results despite algorithmic compensation. So now I’ve been charged with the task of creating a torque coupling that fits on to the rotating shaft. Now, there is no problem building the torque sensor, however, what is a problem is making it small and making it send the signal back to the device.
Also, instead of using an Analog Devices AD7705B 16 bit serial out ADC. Frankly, I’ve never used one but the greater resolution should enable more useful measurements.
Anyways, here’s a picture of the torque coupling before I ravaged it with hot glue.

Torque Coupling
Torque Coupling

It’s pretty fucking ugly but it’ll work for the time being. I did have the ribs that sit under the sensors quite a bit thicker, but there wasn’t enough strain to be useful for measurement, I had to hacksaw the chunks underneath right off.Unfortunately, I believe the polyurethane glue I used has caused strain on the sensor as it cured, I don’t know of it will go any further.

So, I’ve started on the circuit as of yesterday. I have it set up to take the PICKIT2 interface so that I can hot-program it and I setup the serial out board so that I can output debug data. This works thus far. Soon, I’ll be setting up the ADC and attempting to interface with it.

Starting on the ADC circuit
Starting on the ADC circuit

Here is an image dealing with the read/write cycle on the AD7705, also to note is that the AD7705 is MSB first.

The timing for read/write on the AD7705
The timing for read/write on the AD7705

Here’s the site they came from http://www.protongeeks.com/index.php?option=com_content&task=view&id=63&Itemid=27

Anyways, I’m glad to have my equipment back and ready for whatever crap I decide to build. Here’s a picture for posterity:

My bench as of Nov, 2008
My bench as of Nov, 2008

Anyways, I’ll attempt to update this as much as possible, for whoever is interested (or not).

Creating a strain gage coupling

So now I have to find some way of measuring the torque applied between the two shafts of the viscometer. Here’s my idea.

Strain Coupling Model View
Strain Coupling Model View

What you can’t see is that I plan to manufacture it out of plastic, that way the strain gage experiences the most out of the deflection of the part. I’ll use a flexible polyurethane bonding agent for the strain gages, allowing the forces of the strain to work without breaking the bond.

Here’s a through model view:

Strain Coupling Transparent View
Strain Coupling Transparent View

Of course, it only took me a few minute to make this model but it helped me see if what I was doing would work, I also used FEA to see if the forces would be transmitted where I wanted them. The FEA results were promising, nice even strain along the gage surfaces. (Those gauge surfaces are seen in light blue). You can see though that the hole through the side relieves some strain on the strain area, though, this shouldn’t be an issue.

Strain Coupling Strain Test view
Strain Coupling Strain Test view

Here’s an image of the stress as calculated by Cosmos

Strain Coupling Stress Test view
Strain Coupling Stress Test view

Well, hopefully this will work. First I need to get the strain gages to provide reliable results. By using two of them, temperature concerns should no longer be an issue and should help mitigate innacuracies. I’ll post pictures of the finished part, though I don’t think I’ll do it on the NC, I’ll just do it manually, it may look like ass 😉

Graphing program and viscometer proceeding apace

Well, things are proceeding apace as far as the viscometer is concerned. Unfortunately, the motor is just too non-linear to serve as a useful measuring device. God I’m dumb!

Anyways, my graph-it program is working ok now and producing some useful graphs. I have programmed the save and load features and they seem to work just fine! It will eventually allow for a variety of data analysis techniques.

Here’s a picture of the linearity, or lack thereof.

Reciprocal of motor linearity
Reciprocal of motor linearity

The blue at the bottom represents the overall error , the pinkish is the actual reciprocal of the tach values and the brown is the average of the tach values.

Hopefully I can get this working… Sigh!

A new Youtube video

Yes, I haven’t made a new youtube video in some time. Now the video I make is a redux of one I’ve made already, namely Doki Doki Panic. The reason I redid it was because the original wasn’t narrated. This one is, for only to add some personability and add some information to the video about Doki Doki Panic.


Viscometer and Graphing

Now that I’ve got the new board working, I’ve been programming all of the pertinant functions back into the chip. This time I’ve redesigned them to be a little more modular and useful in the long term. As was mentioned in the post a while back, I made a new board and I’ve come to realise that the RS-485 Port is wrong. It has 2 connectors when it requires 3. A-B-Ground. Sigh!

Anyways, I’ve been running tests with the viscometer and everything is working great so far. I’ve got the temperature sensors working and the conditioning of them with OP-amps has worked like a charm. Though I find that the read value from the ADC is pretty jumpy.

Anyways, as reference, here some photos.


The Whole Deal
The Whole Deal

Temp Conditioner
Temp Conditioner


Also, the linearity test went well. Better than I initially expected.

Motor Linearity
Motor Linearity


One can notice that there are some burps along the graph but for the most part, it’s fairly linear as far as I’m concerned.

Writing a new graphing program

Since I’m starting to take measurements based on time and value along with multiple data sets, I’ve decided that I need a new graphing program. This one will allow the use of multiple data sets and it will have save files to allow for easy recall of color settings and data parameters. Here are some of the features:

  • Multiple data sets
  • Data sets will have options for coloring and graphing choices
  • New data sets can be derived from existing data sets
  • Data sets can be compared
  • More extensive stats will be used

.

This will all be written in FreeBASIC. Why? Because I like it. Also because FBEdit kicks ass in relation to FBIDE.

Anyways, I’ll post incremental versions.

New Viscometer Board

Well, my design finally came to fruition from AP Circuits and I can say I’m quite pleased with the results. The overall appearance of it is really nice, for me at least.

Interestingly enough, I had some problems and made some mistakes. I ties the power regulator input into the motor – terminal… weird. Also, I didn’t tie AVdd high, or to anything.

Remember, programming a pic, remember these things

  • Use caps across power
  • tie ALL Vss and Vdd to their respective rails
  • tie AVss and Avdd to their respective rails

I kept ketting a “Error programming at address 0x000000” error and it turned out to be the Avdd was disconnected.

Minolta MD, AF prime lens review

Well, after spending a bit of time collecting prime lenses, I’ve decide to give them a brief review of sorts. The only way that can be objectively done is with a photographic test. Not being one for planning things out, I oped to use an old magazine and a couple of gameboy games as the test, this at least will be less a test of my focusing abilities and more a test of the clarity of the optics at a specified distance. So with no further ado, let’s introduce the lenses.

My Five Primes
My Five Primes

All of these lenses were purchased off EBay. Some of them were cheap, the AF’s however were not so cheap. So, Let’s introduce each lens shall we?

Minolta 28mm F2.8 AF Lens:

This lens thus far has been a pretty good lens. It’s dead sharp and it’s nice and stout.  It has a minimum F of 2.8 and maximum of 22.

And here are the shots taken from the lens. Keep in mind that these are directly from the camera and may look a tad dark. Click on the links to see the full size image, usually your browser will allow switching between sizes.

  1. Minolta AF 28mm Lens at F2.8
  2. Minolta AF 28mm Lens at F8
  3. Minolta AF 28mm Lens at F22

Looking at the pictures, they’re pretty sharp. My own personal opinion is that there is some blurring around the text but color rendition is pretty good.

Minolta 50mm F1.7 AF Lens:

This lens is really nice for portraiture and it has nice bokeh. I find that on my camera, auto-focus tends to focus behind the subject at F1.7.

Here are the test images.

  1. Minolta AF 50mm at F1.7
  2. Minolta AF 50mm at F8
  3. Minolta AF 50mm at F22

On this lens it’s pretty obvious that at F8 it becomes pretty clear  but at F1.7 and F22 there is some blur at the edges of the text. Again, the color rendition is pretty good and the clarity is a bit better than the 28mm AF lens. Something to take note of I guess.

Minolta 28mm F2.8 MD Lens

Something to note on all of these MD lenses is the fact that I used an adapter to facilitate mounting them on the camera. Something else to note is that they’re manual focus lenses and the focus is limited by my own vision, which is good, but not perfect. I tried to focus them via trial and error, however, I may not have gotten everything in focus at the lowest F number.

Here is the 28mm Minolta MD lens,. It feels really nice to focus and is of entirely metal build. It feels solid. Looking at it, it is almost entirely the same as the later model AF lens, certainly the majority of the design was retained for the later lens.

Here are the test images, remember, the color/focus may be different due to the adapter.

  1. Minolta MD 28mm at F2.8
  2. Minolta MD 28mm at F8
  3. Minolta MD 28mm at F22

Based on what I can see, there is little difference between the MD and the AF versions of the lenses. I suspect that my focus was folly in the F2.8 test, though I got it as close as I could over several exposures. There was slightly more chromatic aberration in the F22 test in the MD Lens as well. All in all,  a comparitive lens if you like manual focus.

Minolta 50mm Rokkor F1.4 Lens

I have to say, I really like the look of this lens. The overall appearance of it looks as though it’s of high quality. Again, quality may be skewed due to the adapter. It’s also interesting to note that its maximum aperture is F16, lower than the other lenses.

Here are the test images.

  1. Minolta Rokkor 50mm at F1.4
  2. Minolta Rokkor 50mm at F8
  3. Minolta Rokkor 50mm at F16

I have to say, with this lens at F1.4, everything seems washed out to a large degree however at F8 it appears as though it is somewhat sharper than its AF cousin despite the fact that the exposure is a tad darker. Even at F22 Vs. F16, the Rokkor appears a tad bit clearer, again, it could be the lower exposure time.

Star-D 135mm F2.8 Lens

I bought this lens because I wanted to try a manual focus lens and because it was cheap. Frankly, it’s a piece of shit. Taking a picture in any sort of light washed out the colors and any sort of night photography (with lights) results in halos and U.F.O like apparitions all through the image, though it does have the benefit of being fast. Though it is a prime lens that I own and as such, I figured it’d be worth testing.

Here are the test images.

  1. Star-D 135mm at F2.8
  2. Star-D 135mm at F8
  3. Star-D 135mm at F22

Clearly, this lens is inferior to the other lenses. While it is somewhat clear at F8, the contrast is lower than the other lenses. It’s not a bad lens of there is no other option but I’m going to try and find an AF verison.

Conclusion

Well, I can’t really draw too many conclusions from the images provided. I would need to take pictures in the real world and take images of more three dimensional objects in order to get a better idea of their true qualities. Truly, this is nothing more than a cursory test.

Please, if you have a comment to make, please do so

Also, here is the gallery of images used, for reference: