RobotArm first project ever

Hi,
I am studying electronic engineering and would like to do the following project:
1) make a computer aided design of a robotarm
2) build or buy the constructionparts that I have designed 3) buy about 5 small servomotors for it 4) buy some chips and stuff to get everything working 5) program the chips 6) writing some software so that I can control the arm from my laptop.
But I have never done anything like this before. So this leaves me with a 1000nd questions. I went to the library checked the internet. But after days of searching I made little improvement. I hope some people in this discussion group can help me with some of my questions.
1) Can anybody tell me what my total balance of costs would be?
2) Building the parts: Is it expensive to let some firm produce the parts I have designed? Or am I better of checking some catalog and using default parts. I thought about using LEGO, but my professors would be furious and annoyed if I did do that. Maybe making it in wood is a good idea? Any advice in this field would be welcome.
3) I have very little experience with these computer chips. The only thing I ever did that comes near to this is programming the EPF10K20R240 from Altera in Quartus 2. Are there standard predesigned cards for what I try to do? What do I want? What do I need?
4) I saw there are some default modules available on the market that have functions like "Ethernet", "Light Sensors", "Camera", "Serial Port" etc... Is it hard to put several modules together into 1 system. How does one combine all these modules. Are there controller modules for that? Pfff, I know so little about it. For example, how to split the power of one adapter over the different modules that all require power ofcourse. Are there splitters for that? Probably a very stupid question but I'm overwhelmed by questions like that.
5) I noticed when I programmed the EPF10K20R240 microprocessor, it loses it's program when it loses power. Is there an explanation for that ? Is this common? Do I need to recompile and upload my code again every time?
6) Is there anybody willing to give me regular feedback on msn messenger? My address is: snipped-for-privacy@hotmail.com
Thank you in advance for your patience to read my questions and for all help! BramGo
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snipped-for-privacy@gmail.com wrote:

Does your laptop have a parallel port?
What computer language and do you want to use?
-- JC
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Thank you for your reply JGCASEY
Computer languages: Java, C#, Visual Basic 6, VB.NET, ... I have a little bit basic knowledge of C++ too. And I wouldn't be affraid to learn some new language as long as they aren't too hard. (like assembler would be TOO hard for me I think...)
It only has USB. But if it's worth getting a converter for parallel/serial ports I'll just buy one.
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Hi there
Have you looked at the Basic Stamp from Parallax, http://www.parallax.com. You can program this in PBasic which is pretty close to VB. If you look on the site you'll find some handy manufactured boards to do the controling of your motors for starters.
You can control the Basic stamp from a serial port, I have before. You even get the cable to talk to your "chip" with depending on what you buy. The stamp is quite expensive, $50 but it is really eay to program and nice for beginning and prototyping later. I currently use mine to test first and then build the final product.
You haven't said how much you have to design/build yourself?
I'm designing my own arm currently, I'll let you know if I run into anything unforseen.
Hope this help Fick
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Take a look at these guys. They sell parts that allow you to design your own robotics without wasting a lot of time on all those tiny little details.
http://www.lynxmotion.com/Category.aspx?CategoryID'
-howy
snipped-for-privacy@gmail.com wrote:

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    --The thing I don't like about the lynxmotion kits is they are terribly small and wimpy. I suppose once you know what you're doing you could scale one up, yes?
--
"Steamboat Ed" Haas : Better an early adapter
Hacking the Trailing Edge! : than an early adopter..
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steamer wrote:

Hey Burner buddy ;-)
Scaling up is a pretty big problem because when you, for example, double the height of your bot, you actually create 8 times the mass. Since all your levers double in length as well, you need to generate *16* times the power of the original.
A complete redesign is usually a much better approach.
Matthias
--
http://matthiasm.com/vehicles.html for my BM '00-'03 art cars
http://www.robowerk.com /
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    --Agreed. I went for Stamp (cuz I don't have a clue about circuitry and their tutorial is first rate) and I'm now building big-ass "servos", bwahaha..
--
"Steamboat Ed" Haas : Better an early adapter
Hacking the Trailing Edge! : than an early adopter..
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I made this one (
http://www.waycoolgear.com/er1/servogripper.jpg ) using the servo brackets from LynxMotion, by just connecting them directly to each other. I "stole" the idea for using a hobby clamp for the gripper from Gordon McComb's website: http://www.budgetrobotics.com/shop/index.php?shop=1&cat7 .
I used a Phidgets 4 servo controller board to control the servos. With Phidgets, you can write your own code in C++ or VB, on Windows or Linux, and control them from a USB port.
I just used a couple of cheap L brackets from Home Depot and some scrap mdf wood to mount the servo to it.
This is not a very good design because all of the servos are the same size and strength -- this design requires at least one stronger servo to lift the whole gripper assembly, especially with any payload. It was mostly just an exercise to see how easy it was using Lynxmotion's "servo erector set". It was a breeze!
I think 3 servos + brackets + phidgets board would probably have cost me about $200 if I had bought everything new. Lynxmotion's new aluminum tubing connectors make some really cool looking robotic arms! See this link for a great photo of one of those:
http://www.lynxmotion.com/images/jpg/aarm05.jpg
I had this mounted to my ER1 robot in such a way that I didn't need to the other degree of freedom a 4th servo would have provided:
Hope that helps some ... JCD
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Hi
I have this book:
"Build Your Own Humanoid Robots" by Karl Williams. It has three chapters on building an arm, including VB 6 interface software, and if you want, optional voice control.
The only problem is the microprocessor code is in PIC BASIC Pro - C is the industry standard. A trial (*free* ) C compiler from Hi-Tech www.htsoft.com will program the PIC16F84A no problems The Hi-Tech compiler is one of the industry standard. Porting from PIC BASIC Pro to C will not be trivial for a beginner, but an engineering student should work it out -it depends on how much time you have.BASIC programming for microcontrollers is not recommended for professionals or at university engineering level. The PIC BASIC Pro software is expensive and outdated. As a last resort and you decide to program in BASIC, buy a or build a BASIC Stamp from components available from www.parallax.com. The code is similar to PIC BASIC Pro (you will have to get a PB Pro manual to see which commands are similar to the PBASIC code used for the BASIC Stamp).
The hex code is also supplied with the book, so you could use that 'out of the box' if despearate with the Microchip MPLAB assemble/IDE at www.microchip.com.
Also consider the book "123 PIC Microcontroller Experiments for the Evil Genius" by Myke Predko -an excellent coverage of Hi-Tech C programming and programming in Assembly ( the chip in this book is different to that used in the book "Build Your Own Humanoid Robots" by Karl Williams, but with help from others you should get around this).
If you live in the USA, Microchip will send you some FREE samples, and with the Hi-TEch compiler, you will have free development tools. You can build your own PIC programmer from plans off the Internet, or from tyhe book: "programming Robot Controllers" by Myke Predko.
This beats paying USD $250 for the PIC BASIC Pro compiler, and the outdated PIC Programmer in the book "Build Your Own Humanoid Robots" by Karl Williams.
Cheers
|-]
Dale

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I guess the "selling point" of PIC Basic is that it is BASIC Stamp compatible, so if you come from that environment it's viable option.
Just to clarify a point: The standard Hi-Tech C compiler is not free. They have a PICC Lite compiler that is free, and though for the 84A there are no limitations, it's mostly because this is an enemic chip. Otherwise the software has a 1K or 2K limit, and supports only a subset of processors. Not sure I'd recommend the Lite version for professionals or university labs either (the full version is fine), and the full version is close to a thousand dollars. Anyway, just to put this in perspective. If the lite version is enough for a project, then that's great, but it isn't always the case. Many a project I've started where I realized the lite/demo version was insufficient, and I had to fork over money to complete it.
Replying to the OP through your post: I would seriously reconsider your points 1 and 2 if you've not done this before. It's rather like: "1. Take some art classes. 2. Paint the Mona Lisa." Of course, you could be a mechanical engineer by trade, but you didn't mention it, so I'll just point out that the physical construction of the robot should not be an after-thought. A good base will go a long way to building a reliable arm.
Another approach: Buy off-the-shelf parts if you can. Some systems are more flexible than others. Though I haven't personally tried them, Lynxmotion sells some generic brackets that you can assemble to make various types of servo-based robots. If you don't like your first design you can take it apart and rebuild it. Most standard Futaba and Hitec servos will work with the brackets. You can also fashion your own brackets out of aluminum channel, and build your arm out of those. The benefit of using component parts is that you can change your mind without having to rebuild from scratch.
-- Gordon
Dale T Stewart wrote:

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Hello, you can see my project of a robot arm: http://www.geocities.com/gidesay/roboticarm.html It seems to me very similar to your ideas. I builded all parts myself (except servo motors and chips of course! :-) I use plywood in different thickness. There is one of 3 mm for airplanes models that is as strong and rigid as aluminium! In the site there are details of mechanical construction, electronic card assembly to control the servos from a serial port, source programs for a Pic 16F628 microcontroller, and finally a Delphi program to command arm from the pc. Have fun
Gidesa
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Hello, you can see my project of a robot arm: http://www.geocities.com/gidesay/roboticarm.html It seems to me very similar to your ideas. I builded all parts myself (except servo motors and chips of course! :-) I use plywood in different thickness. There is one of 3 mm for airplanes models that is as strong and rigid as aluminium! In the site there are details of mechanical construction, electronic card assembly to control the servos from a serial port, source programs for a Pic 16F628 microcontroller, and finally a Delphi program to command arm from the pc. Have fun
Gidesa
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great job on the wood arm!
Rich
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First of all I would like to thank all of you!
The lynxmotion parts look very nice, but too expensive for me.
I am not sure what kind of material I will use for the arm. I think I might go for wood after all. Light, strong, easy to get my hands on, ... It's something I can easely do on my own. I guess this will save me a lot of money.
And I figured it's probably better to do the electronics first. Either way I will need to know the sizes of the servos before designing the construction parts of the arm.
I had a lot of nice replies of all of you. But the most helpful one of all was the one of Gidesa. (http://www.geocities.com/gidesay/roboticarm.html ) I must say your website is really impressive. But I was stuck with a lot of small questions on your diagram of the electronics.
Yesterday I took all my courage together and took your diagram to one of my profs of "digital electronics and communication technology". He explained me a lot. Turns out most of my questions like "why use a 18pF component?, why the 240 ohm?, why use a polarized capacitor?". My prof explained me that most of these details just come straight from the manual. He showed me the manuals of the MAX232, PIC16F628 and LM317. And indeed all my questions seemed to be answered in there.
So the most important lesson I learned here is: digital electronics is not about small details like in analog electronics: capacitors, diodes, etc... . But it's about making a selection of the chips and then looking up the required smaller components that are necessary without worrying too much about them.
My prof also told me I could use the programmers that are available at school. He also warned me that I should order my chips before the diodes and capacitors, because sometimes electronic shops sell different types of MAX232 chips that might require different kind of capacitors.
So what I am going to do now is compare prices and look for a board to mount all my parts on. I checked some websites so far and this really doesn't look that expensive at all. I guess total costs of the electronics components will be 15 at most. PIC16F628: 5,35 MAX232: 1,94 LM317: 2x0,38 a cheap LED: 0,119
Does anybody know a good website for circuit boards for soldering my components on? And maybe somebody knows a good website for servos?
Thank you for all the nice replies so far.
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Bvanden, thanks for your preference for my site! :-) Indeed I completely agree with your professor. I am only a novice in electronic, but I find that when using IC many of the circuital details are just "written" in datasheet. Of course in industrial projects the chips are choosen with great attention, but in our simplified projects the main rule is: I choose the chip more cheap and more easy to find and use! :-) In my circuit schemes many parts are really standard sub-circuits taken from 16F628 or MAX232 or Lm317 datasheets. The main problems I had in testing the circuit after the solders. Every time sometimes was bad, but was also difficult to discover what was bad! Anyway I built these circuits with very simple materials, a solder, a board and wire. And they work, no matter of my really not perfect solders. Here an hints: Maxim and also Microchip send samples of their IC at no cost! Go on their website and sign with a valid email (no google, yahoo, ecc.) and postal address. And in few weeks you will receive some IC, also Pic 16F628! Of course be moderate, do not request too many pieces! two of every types is sufficient. For servos I know an italian site where I bought someones.
gidesa
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Thank you for the hint ;-)
Ordered samples from the PIC16F628 and some kind of MAX232 chip.
Oh, now that I think about it: Do you have any idea what kind of chip I would need if I wanted to use USB instead of the serial connector? I figured that would be handy since USB also delivers some power. So, maybe I wouldn't need the battery connectors that way. Would the power supplied by the pc (through the USB cable) be enough to power all chips and the servos?
Would be pretty cool I think :).
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The power from USB could be enough for the electronic part, it's just good to maintain the "brain" power distinct from "muscle" power. But absolutely not for servos! Maybe at max 1 servo, but I have doubts. When I use my adapter circuit from 12 v to 6 v with Lm317 to power the 6 servos, it becomes soon very hot! Remember to screw a metal hot discharger to the Lm317. I think all 6 servos can consume around 1,5-2 ampere, for a total power at 6 v of 9 -12 watt. The most hot servo is the one in the "elbow", it must balance continuosly the load at the gripper, plus the 3 wrist-gripper servos. The serial connection is very simple electrical, only 3 wires (ground, tx, rx), and as a protocol. I think that USB is much more complicated as a protocol, but I have not direct experience on it. Regards
gidesa
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I found a great link to make my own PIC compiler.
The site says it works for the PIC16F628 (and the PIC16F84A). It seems to be a very simple circuit.
The say I only need: 1x 15kO 1x 10KO 1x 100uF capacitor 1x BC547B transistor 1x 5,1V zenerdiode 1x 18 pin's ic socket 1x DB9 connector (RS232)
It says total costs should be about 1,5 . What a contrast to the commercial versions that cost about 100 $.
I hope this helps other people that were concidering to buy a programmer. :-).
Greetings BramGo
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Forgot to mention the URL.
Link: http://www.circuitsonline.net/circuits/view/91
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