the crypt

Gordon McComb wrote:


They can't be enthusiasts than :) Most people will spend thousands of $ on a hobby that interests them.

All my robot bases have been big enough to carry a Mini_ITX board. One was built out of welded steel, solid wheels and uses 24 volt window wiper motors as at the time I was going to use my old PC (I update about every three years :-) ). The PC ran off a 12 volt battery + inverter.

If the robot is worth building, that is can do things worth while, I would spend $5,000! Some car hobbyists spend a lot more than that on their hobby.
However for a mass production robot I agree. That is why I see a radio link to a home computer as the most cost effective solution. There are wireless web cams available now that people can buy for security and child monitoring.

If you need the computing power it is the cheapest solution.
There are many simple control systems that don't need that much computing power but advanced vision and advanced robots will need it.

Yes I have used VB5 to grab images although it was a bit slow and not really ideal. At the moment I am using VC++ with some success. But to be honest the teach yourself VC++ in 21 days didn't really cut it and I have found it difficult to get help from experts. Yes I tried the VC++ newsgroups with nothing but cryptic replies that if I could understand them I wouldn't have asked the question. I used the DJGPP C++ for DOS to capture and process images from the old monochrome QuickCam for which you could get the interface specs.
May I point out I am *only* a hobbyist in electronics and programming with other things that take up my time.

I just googled the Sourceforge library. At this stage I don't see any tutorials on how to use it.
I do remember something about the .NET compiler for free. The books required to get up to speed cost more than the $70 visual system however, and will they be any better than the teach yourself VC++ books I have? I doubt it. I am a hobbyist programmer with limited spare time not a professional.

Well yes I have done all that kind of image processing :)

Ok will have to try and track down where I can get the articles. I live in Australia a long way from the major cities.

Another poster, mlw, can use Linux and says grabbing images is a piece of cake. Well I await a *complete* example program of how he will do it if he ever does. Vague explanations and snippets of code just don't cut it for anyone except a professional programmer.

Do you write from personal experience?
-- John
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JGCASEY wrote:

Adults yes, and adults can and do spend lots of $$$ on their robots. Have you taken a look at DPA's robots? These aren't cheap. However, not everyone has this budget. I know I don't.

So what about this craft doesn't require an investment of some kind for learning?
BTW, the $75 vision doesn't exist! If it did, we wouldn't be having this discussion. It would just be a URL to where you could buy it. Since it doesn't, you either have to spend more for something like a CMUcam2 (not a bad product), or roll your own.

Dick Smith sells SERVO mag, but it is available by subscription to Australia. The vision articles might have been woth the subscription price alone. However if all you want is to play with the vision libraries ytou can download them from here: http://www.robinhewitt.com . Look at Mavis.

Yes, but I'm just a beginner in this area. I've tinkered with extracting bitmaps and doing simple compares, trying a variety of freeware DirectShow filters that detect motion, and tried some demo versions of commercial image libraries (Montivision, LEAD, etc.). Lots of stuff to play with, and so far I haven't written a line of C++ code.
-- Gordon
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Gordon McComb wrote:

I guess I was spoiled by the easy to learn simplicity of DOS that I have found the bureaucratic monstrosity called Windows and its MFC a rather large and obscure tome to deal with. When I dreamt of the day computers would have sufficient speed and memory to do vision in real time it never occurred to me the time taken to learn to do something simple like display a bitmap stored in an array would become so complex.
That's progress I guess :-)
-- JC
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JGCASEY wrote:

I wouldn't mind learning the arcane series of incantations so much if I didn't have to learn new ones every time they change things.
The raw Win16/Win32 API is the most long lasting version for Windows.
Linux/UNIX is interesting as well.
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"Gordon McComb" wrote

<snip>
Now I know what that means. I'm still shopping for components in order to automate my ATV. Because it is funded by my school, it needs to be reproduceable (no ebay, surplus, etc), and it is indecently expensive to buy motors, encoders, gearheads, controllers for things that require a good amount of force to be pushed around.
Cheers
Padu
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Gordon McComb wrote:

There is plenty of vision software available for Linux. The Video4Linux API is built into the kernel. There are several Sourceforge projects, the best is Intel's Open Source Computer Vision Library:
http://sourceforge.net/projects/opencvlibrary / http://www.intel.com/technology/computing/opencv
The biggest problem for Linux is that most camera manufacturers provide binary-only drivers for Windows, and won't release the specs so someone can write a Linux driver. This problem is getting worse, with some vendors (such as Logitech) that released specs on their early cameras, refusing to do so on their newer cameras. I guess they figure all the tech support inquiries from random Linux geeks who can't get their drivers to work, isn't worth the tiny increase in sales.
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Gordon the Linux world is eat up with free software for vision processing, including some developed by Intel and several major universities. As for C++, there are tons of win32 IDE's, compilers, libraries etc.. Google is the king as far as finding that stuff is concerned. I personally use DEV-C++ and MinGW for my Windows developing. It reminds me of the old Borland IDE and can be used with many more languages. If I remember correctly they also have a Linux version.
Eljin
Gordon McComb wrote:

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Hi

Some of them are :>)
The LEGO robot and SR04 are both in the under $300 catagory. It's the time that costs the most.
The most expensive part of the robots I've built lately are the industrial grade IMUs on nBot ($800) and jBot ($1800). But I doubt I have more than $1200 in nBot total (not counting time!!!) and probably $3000 in jBot total.
That might be a lot for a hobby robot, but it's not realy a lot for a hobby. Consider all the ATVs out there (usually $5000 or higher) the sailboats, dirtbikes, etc. And most of these are bought by normal working-class folks like us.
As for the expensive sensors, these are the prices most likely to come down, especially as experimentalists like us find nifty uses for the technology. By the time full 6-axis IMUs are 50 bucks, we'll already know how to use them. Hopefully.
I think I tend to agree with Gordon's (?) earlier comment that price is not really the main deteminate. The thing in short supply is really not money, it's cool ideas.
So, here's how I got the IMU for jBot. My wife wanted some new furniture. So she got her couch and chairs. And I got an IMU.
Try it! It might work for you!
best, dpa
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Hi
Here's a simple/cheap video application using the video4linux drivers, a winTV card, and a cheap NTSC B&W video camera. Not a robotics application, but you have to start somewhere.
There is a camera mounted outside the door of my office. A frame is grabbed about 4 times per second and compared to a reference frame. If enough pixels differ by enough of a threshold, then the frame is timestamped, compressed, and saved.
If the number of pixels that have changed is large enough, it's probaby somebody standing outside the door, so it also puts an asterix at the start of the time stamp, and plays a little .wav file that goes "tock" to get my attention.
Here's a little movie of the typical activity outside my office, played backwards just for fun. That's me at the end, spinning down the hall and thumbing my nose at the camera. I just moved once for each time I heard the "tock" coming from inside the office, to make my own little animation.
<http://www.geology.smu.edu/~dpa-www/mpeg/18sep03_rev.mpg>
There is another cheapy video4linux application running this evening (and every tuesday evening) from the DPRG RBNO, all with cheap hardware and free software:
<http://www.dprg.org/lab/>
best, dpa
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Just a question...
Was the mucho dinero spent on the high end inertial components worth it compared to the lesser units out there?
Mike

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blueeyedpop wrote:

Yes.
Well. maybe I should ask, what lesser units?
For the balancing robot, I spent about a year working on my own IMU, which I got to work reasonably well, but not really well. Not as well as a pot with a stick dragging on the floor At that time I decided that I was spending a lot of energy working on a problem (mastery of extended Kalman filtering) that was really tangential to the problem I was actually trying to solve. So I bought the single axis IMU and went back to work on the part that I was really interested in, the robot.
I have several friends that have gotten home-brew IMUs to work reasonably well, but not really well. For example., their robots don't appear to be able to handle the rough off-road terrain that nBot has been able to. The difference might be our control code, but I don't think so. I think it is the sensor.
For jBot, the cool thing about the IMU it uses is that it includes a 3 axis magnetometer with the 3axis accelerometers and gyroscopes. This allows me to use the device as a 3D source for the theta parameter of odometery, which trivializes a lot of the navigation errors. That's why the robot can travel 1000 feet through the woods and get back to within a couple of feet of it's starting location, all without using GPS.
In honesty I haven't yet seen another robot that can do the same for comparison, so I don't really know the answer to that question. Although I've been trying really hard to get Randy to build (or better yet, have built) a similar platform...
cheers dpa

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I wuilt a balancer with a "bare" analog devices accel, and and a silicon sensing systems gyro, which performed moderately crappy with about 20 minutes of coding.
At the last employer, we were using BEI systron gyros for sub degree sensitivity.
I can spend anywhere from 2K for an o-navi, 4-5K for a Rotomotion, 10K for a Crossbow, or 26K for a BEI.
I wonder how good is good enough to keep robots from tipping over on rough terrain. Have you done any studies on known terrain, comparing IMU data to reality, and calculating how poor your IMU can be?
Mike

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Here's my current setup for vision on a PC.
- Use a webcam - Logitech 4000Pro's are a good model near the specified price point.
- Use the Intel's OpenCV to import the pictures on a PC. (http://www.intel.com/technology/computing/opencv/index.htm )
- Use CMVision to quickly find colored objects (http://www.cs.cmu.edu/~jbruce/cmvision/)
- Use Qt for a nice GUI interface. (http://www.trolltech.com/download/opensource.html )
- Use MinGW for a MSWindows compiler (http://mingw.org /)
For a robot, the steps are similar. We have some custom camera to DSP interface boards at my school. Reading in the images doesn't require any fancy library. I will probably port CMVision or something similar to C for the DSP this semester.
Later, Daniel
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Daniel, Didn't want your post to go without a *thank you* for providing some really great links.
While on the subject, have you found the color correction in the Logitech's a problem if you do color blob analysis? Are you able to get into the raw format of the camera (like the program here does for still cameras: http://www.pl32.com/pages/digicam.php ), or do you just pick up the corrected image as sent to the PC through the driver?
-- Gordon
D Herring wrote:

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Gordon McComb wrote:

No problem.

I'm just using the built-in color correction. To stabilize things, there is a setting to disable auto color adaptation and enter fixed settings. It also helps if you convert the image to HSL or HSV (http://en.wikipedia.org/wiki/HSV_color_space ) before thresholding. These color spaces are better for specifying object colors than using RGB directly.
On Linux, you might be able to use/modify the Philips WebCam (pwc) driver to obtain pixels in the native camera format; but this is of little interest to me.
Later, Daniel
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On Mon, 30 Jan 2006 11:34:58 -0800, Gordon McComb wrote:

Another explanation, at least for the US is the economy. Times were pretty darn good in the late 90's and peaking around 2000. Then it sort've went bust, at least for a lot of techies which make up this hobby. So instead of a little extra leisure time and a little extra cash to spend building robots, those same people instead are working the second job at night trying to feed and clothe their kids. Or working extra hard to try and not get laid off. Or were laid off and then went on the job hunt - no time for anything but economic survival.
-Brian
--
Brian Dean
ATmega128 based MAVRIC controllers
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And yet here I am (next sunday) looking for something interesting to talk about. Go figure.
But like you, I didn't go to dpa's site, because I have gone there many times before. Figured I knew what he had up there. So I looked. I hadn't seen it before on his videos, but I had seen that behavior before in person.
--
Randy M. Dumse

Caution: Objects in mirror are more confused than they appear.
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You know, I don't think it is as simple as that. (Forgive my biased opinion, but I truly believe:) The IsoPod(TM) was a $99 microcontroller better suited to robotics and motion control than anything industry had ever created. While there were notable exceptions, overall sales to hobbiest have been dismal enough I've discontinued advertizing. I think my HC11 boards did more for robotics, as I am fairly sure the MIT Handiboard was inspired out of my product line.
I think BattleBots had more to do with the 2000 spike in robotics, and 2001 and having real battles to fight did more to undo the spike than products or technologies. There are deeper societal trends afoot than lack or availability of nifty new products.
I'd like to think some new product could open up new worlds. I strive all the time to find them. For instance, it seems Bob has hit a homer with his Maxsonar-EZ1. The innovation is making it half size. But will it make a new wave of interest in robotics. I have my doubts.
You (Gordon) and I discussed a new sonar two or three years ago. We wondered if mounting them on a cheap scanning motor wouldn't be a good idea. I wondered if making them a tenth the size would open new markets and increase uses. So it isn't that the idea was missing. It just seemed Gerald Coe was doing a good job with his products. Clearly Parallax saw the niche as well, and did the PING. Gerald has responded with some new innovations, SRF05, SRF10, etc. Now Bob has announced. Still, I don't think this new wave of sonars will cause a new wave of robot construction.
Likewise, the CMUCam was an exciting new entry. But how many robots really make use of it? I'll bet there are10 or even 20 times the number of CMUCam's owned, than there are CMUCam's actually mounted on robots. I know mine is in a box. I even have worked out what I think is a viable plan to have predictive line following. I have written the interface to send and capture every camera command.
Seems to me the CMUCamII was a move in the opposite direction, bigger, more power hungry, harder to use (odd changes in communications vs. extentions and additions). So, why will a 25% reduction in the cost of a new "vision" system under the under utilized CMUCam's make for a new wave?
It's something else. It's a deeper driven wave than just waiting for the introduction of one product.
As I've already said, I am constantly thinking on how to make significant improvements in peripherals and sensors, and I'd like to believe something like those could energize a new wave in robotics, (See our 'Pod's, see our $29 ARM, look for our new high end H-bridge, look for our new low end H-bridge, look for our new Differential Drive Module, look for our new line of sensors... etc.) but I don't really take that opinion too seriously, because I've been proven wrong before, and often wrong lately. It's something else.
--
Randy M. Dumse
www.newmicros.com
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Randy M. Dumse wrote:

<snip>
You're right; it's not as simple as that. But newsgroup postings aren't great at providing a platform for complete analysis and reportage, and for something as complex as consumer buying patterns, no one thread will cover it all.
One part of the equation that's missing is how well the product is marketed to its audience. What the product had to offer, and how the market perceived its value, don't always coincide. Betamax was arguably the better tape format, but it lost out because its creators were convinced that it would be the dominant player simply because it was better. As we all know that's not how the story went.
What keeps people in the BASIC Stamp camp, or using 8-bit processors, is not the capability of the hardware, but the availability of examples and other support materials. Parallax has built an entire business not on a microcontroller, but on support for that microcontroller.

Absolutely it did contribute, but fads are like that. Robotics has largely followed the hobby electronics trends. As someone in this biz for a while, I'm sure you remember the ups and downs. As I've said before, this is a natural cycle, and I've been watching it for the past 35+ years. Having written for electonics magazines since the late 70s, I watched my ability to place articles rise and fall with the trends of the hobby.

I also have my doubts, though I wish Bob's product well. Gerry already had introduced smaller units, though at something of a premium price, and to me they didn't seem to be barn burners (but, I don't have insider knowledge here, so maybe they were). I'm not sure size has ever been a compelling issue with ultrasonic sensors, as the SRF04/08 were already pretty small. Or even the issue of accuracy. The logjam today is the lack of suitable examples to use what's already available.

I agree, because these products are not revolutionary in concept. They are incremental improvements of what's been out for 6+ years. It's becoming something of a commodity business, which is largely played by the price card. The winner is the person who can outlast the competition, given smaller and smaller margins. It's not a business segment I'd be interested in pursuing, I can tell you that.

Like the shortcomings with sonar, the problem with vision is the lack of example code to make it fully functional to the average experimenter. There really is a dearth of examples. I have many things competing for my time. I'm not likely to mess with some new piece of hardware unless it offers at least a degree of plug-and-playability.

I'd rather see lots and lots of examples, so that I'm not stuck reinventing the wheel to do common -- and not so common -- tasks. These sound like great products, but how fast can I develop something from them? Are there ready-to-go samples that will help me? Preferably not ina language I'm not likely to be familiar with. The best car in the world isn't worth much if isn't filled with gas; roads aren't as useful without a map. IMO, the actual product is maybe 25 percent of the effort in making something successful. The rest maybe something like this: 25% user education and support, 25% advertising, marketing, and other promotion, and 25% sheer luck. YMMV.
-- Gordon
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dpa wrote:

The UserFriendly cartoon (http://www.userfiendly.org ) had an interesting clip that drew the conclusion that blogs are the new usenet.
Other than that, c.r.m is sort of esoteric. While you may not have appreciated my post on PID (I think we have philosophical differences), it is one of the things that I think this group needs.
Right now, it feels more like a "support group," as people post questions and hope for answers. Because of this, people won't come here to see new stuff.
I also sense, and it is hard to articulate, it is like disrespect. (everyone is guilty on some level) Sure this is usenet, but look at the thread for my PID essay. I posted a link to something I thought would make good reading for someone new or just beginning. I was asking for critique. Now there was some useful criticism, and some off topic criticism like colored comments. Those aren't bad, then there was yours, which at the very beginning seemed to imply that I hadn't done what I wrote about or at the very least attempted to minimize it, the thread quickly got out of hand. There is clearly no incentive now to write about how to hack up a simple ball mouse and make it a dual motor encoder or the other aspects of the $500 robot.
Building and maintaining a community takes, if not work, at least activity. I love robotics, I built my first robot in (I think I remember) 1978, based on an old BigTrac and a COSMAC 1802, maybe it is like Heathkit, no longer generally interesting.
People need to post, to share, to create and to feel encouraged to do so.
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