First Innovation in Robotic Sensors in 3 years!

First Innovation in Robotic Sensors in 3 years!
Terry Fritz, a Colorado based engineer and creator of award winning robots,
has designed the first new sensor to come on the market for robotics in several years.
Mr. Fritz calls the sensor: ThereminVision in honor of Leon Thermin who invented and patented a musical instrument in 1919, which is played by moving hands near a pair of antennas.
The advantage of Thereminvison II over current technology , infrared sensors, is that, with properly places antennas, you can have a full 360 degree detection zone.
The principle of the sensor is based upon the fact that there is a very weak electromagnetic field which surrounds an antenna. When a conductor enters the electromagnetic field, it changes the field's capacity in a measurable way. This conductor can be a hand or a metal object such as a robot. Almost all objects have some detectable capacitance which changes the electromagnetic field.
ThereminVision II is an inexpensive kit, which when assembled (requires soldering) allows experimenters and robotics enthusiasts to detect when objects approach. The output from the kit is wired to a microprocessor, which is not supplied with the kit. The kit consists of four(4) sensor boards and a processor board. The sensor boards, when placed at the 4 corners of a robot and connected to antennas, form an electromagnetic field around the robot which is a zone of detection for objects that approach.
A microprocessor connects to the kit's processor board and polls the sensors. As an object approaches the sensor's antenna, the sensor will send smaller and smaller numbers to the microprocessor until the object touches the antenna and then the output is one's and zeros. The antenna is NOT included since the kit builder needs to incorporate it into his design. The antenna could consist of a single wire(for testing only) extending upwards from the sensor or a metal tube which has a larger detection range. Design guidelines are in the manual noting that the antenna should be rigid. Sample programs are also included in the manual.
Features of the kit include:
**Four sensors, Each sensor weighs 3.7 grams, draws far less than 1mA at 5 volts, and is less than 1 x 1.25 inches.
**The processor, a separate board, weighing 10.7 grams, at less than 1mA at 5 volts, and is 1.3 x 2.4 inches.
**There are two digital control lines and one output signal line connected to a microprocessor which measures pulse width. An optional control line turns the sensors off.
**Power can easily be drawn off the +5volts of most microprocessor supplies.
**Detection range is proportional to the antenna and object surface area. See manual for details. For example, a small robot with inch x 3-inch rigid copper strips as an antennas, the detection range could be 12 - 15 inches. Programming could randomly move the robot until an object is detected.
** Manual is downloaded and not sent with kit. Complete schematics are supplied noting that the printed circuit board layouts are copyrighted. Needs wire and electrical solder to assemble, also not supplied with kit.
A demonstration robot and a kit can be seen at:
www.robotlandinc.com/tvision.htm
Kit is price at $50. U.S. (plus S&H)
Mr. Fritz has a site devoted this subject which is also an excellent subject resource at: www.thereminvision.com
There is a discussion group devoted to Thereminvision II kit at: http://groups.yahoo.com/group/thereminvision /
Kits can be purchased at: www.robotlandinc.com
###
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Bob Leonard wrote:

Strange. This sounds like a more clunky version of the Motorala e-Field sensor. -- D. Jay Newman http://enerd.ws/robots /
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robots,
weak
Almost
field
send
The
Sample
at
supplies.
This looks to be a rip off of Motorola's E field sensor devices. Looks like someone violated someone's patents. Besides Motorola was giving them away free for a Circuit Cellar contest last year. I wonder if he used the Motorola chips in his system?
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last
Did they licence Q-Prox?
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This is an old, old idea. It was once called a "capacity operated relay". There are lots of variations on this theme, running touchscreens, touch lamps, elevator buttons, and related devices.
Now the next thing would be to build a time of flight/phased array version. Get real distance measurements. And, sure enough, somebody has done that.
http://www.sensorsmag.com/articles/0304/14/main.shtml
                John Nagle
Dave VanHorn wrote:

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Friction Stir Welding! Now that is a really cool idea, thing, thought.
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It's more than an idea/thought.     http://www.eclipseaviation.com/progress/milestones/20040508.htm
--kyler
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The other chips that are discussed are not appropriate.
On the discussion group site:
http://groups.yahoo.com/group/thereminvision /
Mr. Fritz writes about the Motorola chip, e.g. which I have copied below:
I first started this project using the MC33974 back in mid November. I overnighted the eval kit in from DigiKey thinking I would be all set...
Unfortunately, the MC33974 is very insensitive. It can detect a car seat (it's real use) but it cannot detect to the fine levels needed for robot work. With a 10 bit AtoD (it has analog output), the chip can go to 0.1pF if you are "really" lucky. Most of the details I stuck here:
http://hot-streamer.com/temp/MC33974EvalKitCD /
Although neat for many uses, it was instantly obvious that the chip was not going to work for the range of 0.0001pF which such a system really needs. I gave the kit to a guy at the robot club for his object grabber where it might be more useful (I think I also have a bunch of bare chips in my junk box...). I then started looking into the theremin's circuits. There was a version-I which used all analog circuits that is still described at:
http://thereminvision.com /
However, the new all digital version is vastly better and really made this whole system fly:
http://thereminvision.com/version-2/TV-II-index.html
ThereminVision can detect capacitance levels about to 1/10000th what the Motorola chip can. The Motorola chip does have nine channels and can do shield referenced antennas which is cool, but the sensitivity is just not there.
http://hot-streamer.com/temp/MC33974EvalKitCD/CD33794DWBEVM % 20Documentation/MC33794.pdf
The key difference is that the Motorola chip just sets up a 120kHz capacitance controlled oscillator and measures the frequency delta directly. A nice solid thing for critical car safety systems, but too insensitive in our case. However, ThereminVision "heterodynes" the oscillator signal with a reference signal just like the theremin instrument to run the sensitivity way up while still remaining stable. That is the key difference. This is all explained in the manual under "Theory of Operation" on page 5.
http://thereminvision.com/version-2/ThereminVision-II-manual.pdf
What is really sad is that apparently the Motorola chip was originally going to heterodyne the signal against a reference and be very sensitive just like the theremin. I might guess that the analog designers were just not able to get it going or the car application changed there plans with million piece sales prospects. ThereminVision could actually be adjusted to be just as insensitive as the MC33974 if anyone really wanted too. If they had just gone all digital and allowed for the full range of sensitivity adjustment, the Motorola chip might have been perfect for everyone!! But they didn't... Maybe someday they will... The Motorola package is also pretty messy for home soldering and such. They added a bunch of automotive things too like the incandescent dash board light driver circuits (it does have an error signal if it burns out :-p).
If I have not already told you far more than you wanted to know ;-)) Here are two posts that go over this too:
http://groups.yahoo.com/group/FrontRangeRobotics/message/1678
http://groups.yahoo.com/group/FrontRangeRobotics/message/1711
There has been a long running saga about this at:
http://groups.yahoo.com/group/FrontRangeRobotics/messages/1697
All the relevant posts are "MC33947" or "ThereminVision" reports.
Cheers,
Terry
(via Bob Leonard)
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Bob Leonard wrote:

Sorry, but I feel that the other chips discussed are higly appropriate.
This is a robotics newsgroup, and not an advertisment for the theremevision.
Also, the first posting stated that the theremevision was a "new" and "innovative" sensor. Indeed, the claim was that it was the "First Innovation in Robotic Sensors in 3 Years".
Frankly, this is what I was disputing. This is *not* an innovation. It is merely an improvement of an existing sensor technology. -- D. Jay Newman http://enerd.ws/robots /
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Agreed.
It's a nicely executed project, though.
Once you get past the awful web site design and find the manual
http://thereminvision.com/version-2/ThereminVision-II-manual.pdf
there's some good stuff in there.
                John Nagle
D. Jay Newman wrote:

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John Nagle wrote:

Yes, I can see that now. Unfortunately I didn't see that in my first look at the web site.
They look interesting, but I *really* hate two things about this site:
1. The blinking text! I hope there is a special place in hell for the programmer who inserted the "blick" tag into HTML.
2. Even worse, I couldn't find the price for the kits until I actually clicked the "buy" button. I then had to cancel the purchace as all I was looking for was the price. Plus it took several clicks to get to this place.
On the other hand, I will probably buy a kit next month or so. -- D. Jay Newman
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I think advertisements are welcomed if they are robot related. I just bought one of these kits for 50 bucks for my ER1 platform and will post the test results here.

The subject line may be a bit exaggerated but it did catch my attention. I don't think it's a big deal if the product is affordable and can improve our robots. We'll see.
DT
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Danh Trinh wrote:

Agreed. My objection was not to the original posting being an advertisement, but to Bob's attempt to close discussion about the topic.

I'll probably purchace a kit next month. This month I already have enough budgeted under the topic "robotics". -- D. Jay Newman http://enerd.ws/robots /
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1.A close friend called the web site 'Visually Unappealing'. My own characterization is: Amateurish. And I wrote it. I'm obviously not a web designer. The web site was rushed. The Web design company told me, at he last minute, they were over-comitted. The site will get a facelift (hopefully sooner than later)
2. I'm sorry if it appeared I wanted to shut-down a discussion. That was not my intent. I wanted to point out that the kit designer did not like the chips being discussed and his reasons for rejecting those chips.
3. I could have made it more clear, I suppose, that if you had any questions for Mr. Fritz, he is monitoring the discussion group on Yahoo and I'm sure would respond to any Yahoo posts
Bob Leonard

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wrote:
Good luck responding to Yahoo posts. I quit trying to use that crappy, unreliable forum.
BRW

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Indeed. I hope someone with more information posts here where everyone can easily follow.
I'm thinking that these sensors *might* be useful for detecting obstacles around a wheelchair robot I'm trying to develop as a research project.
--kyler
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Bennet Williams wrote:

I still follow a couple of groups which are only on Yahoo, but their licencing policies pretty much keep me from posting code there. -- D. Jay Newman http://enerd.ws/robots /
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wrote:

So, what was that innovation three years ago???

----- http://mindspring.com/~benbradley
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Hmmm. I went to the website. Looked for about three and a half seconds, and didn't see how this is a "vision" system.... went back while writing this just to make sure, and took a longer look. Understand, I am not knocking it... looks like a useful proximity system. It just doesn't seem to be what I'd call "vision."
Am I correct in my understanding that the four antennas on the corners of the example 'bot are the sensors? And that the information they give can be interpreted to give a direction, from a reference point at the center of mass of the four antennas, to a nearby object? The website was kind of sketchy on the kind of data that the thing would collect...
Does it resolve distance too, or just direction?
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be
The kit designer responded to you question on the discussion group: http://groups.yahoo.com/group/thereminvision /
His answer is below:
Hi,
I really did not think about the name very much. I wanted to certainly credit Leon Theremin. I quickly though of a few terms and just started using "ThereminVision". Then I made PC file directories called ThereminVision and started naming all the files with it. For better or worse, that is the name that stuck. If I had thought about it "too" long, it may have been named something like "Pentium", "palladium", or ".net" :0))) I guess I really like the name. The "theremin" right off tells a lot of people how it works and the "vision" thing sort of indicates it help a robot "see" what's going on out there. But it is certainly not like a TV camera or true image processing thing at all.
The four antennas are indeed proximity sensors. They detect capacitance change caused by an object near the antennas. If we take the case of just one antenna, there is no direction information since the object would "look" the same in any direction. With two antennas, we can tell if the object is closer to one more than the other or if the object is centered (near equal readings). We still really would not know where in the center it is (front, true center, behind), but rather that it is just equally distant to the two antennas. With three antennas, you can "triangulate" and pretty much determine the general direction. Four antennas fit most robots well so there ended up being four. The number of antennas "could be" more or less. Four just worked out well without adding complexity in our case.
For distance, we can just look at the one antenna case as an example. If we have a reading of say 1000, we don't really know if it is a full size car 10 feet away or a fly sitting on the antenna. Each could give the same reading. A tiny fly very very close, or a giant metal object far off. But we can guess about "what" we are looking for. Say it is a 10cm x 10cm sumo robot that we are really looking for. Since all little sumos will "look" very much the same. We could make a little table of readings vs. distance and it would be fairly close for all sumos.
I should point out that one may not really need to worry too much about distance. In my case, I just look for "anything" out there and attack it >:o)) In a Critter Crunch match, there is only one other thing out there, the opponent robot, so I go for it. One "could" make things very complex by reducing the readings to degrees, velocity, meters, Farads... but the number crunching gets to be hard for a little microcontroller. But if one wants to crunch the numbers, you could get a lot of info other than just which direction to attack.
Cheers,
Terry
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