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Author Topic: New to robotics; Lots of questions  (Read 1466 times)

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Offline PyroTopic starter

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New to robotics; Lots of questions
« on: September 04, 2009, 08:02:41 PM »
Hey everyone.  I'm new to robotics (as the title implies), and would like to jump in head first with my own project.  I have done some work with electronics, but just have some basic knowledge of how things work, nothing too advanced.  I do program a bit, and have used HTML/CSS/JavaScript, as well as some C++ and quite a bit of Visual Basic.  I have always been good with anything that I do with my hands, so I'm hoping I'll catch on fast :)

For right now, I'm just wanting to get a chassis constructed and have the essential electronics to get it to a mobile and programmable state, and then expand from there.  This will be a moderately small rig (about the size of a 1/16th or 1/18th scale RC car, if that helps at all).  I am making the chassis myself, and will be fabricating almost everything myself.  One thing that I'd really like to do is to be able to build my own electronics, and I feel that would greatly improve my understanding of how everything works, and would be a fun project.  I'm not sure if there are certain things that are not possible for someone to build or not, so that's my first question; What do I need, and am I able to build it myself?  I would like to be able to run Linux on this robot, so I'd like to be able to incorporate my own memory in some way (SD card?).

So right now I'm just kind of brainstorming and trying to find a fun little project.  As mentioned above, I basically just need to know if this task is possible. 

Thanks,

- Pyro

Offline Half Shell

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Re: New to robotics; Lots of questions
« Reply #1 on: September 04, 2009, 08:32:00 PM »
There are a lot of "IF this, then you can do that"'s to your questions. This isn't a bad thing - you just need to specify where you're looking to learn, what you're willing to spend, and what you're wanting to do.

If you want to teach yourself embedded systems, build up all the circuits from scratch and have a micro controller control your servos/motors, deal with sensor input, etc etc, then a simple micro controller starter kit would be a huge help to you. Arduino and Axon are two excellent suggestions, and I also highly recommend the AVR STK500 (only around 80 dollars and programs all 8 bit AVRs). You won't be able to run Linux on these - instead you will be programming them in C and will run consistently. There are also memory and storage limits to worry about. You won't be doing high level stuff like vision recognition or massive mapping and localization. On the plus side, the basics of even the most advanced robots in the world come down to hundreds if not thousands of micro controllers controlling sub systems of the robot.

Still more, it is possible with the aforementioned micro controllers to connect wirelessly to a PC, allowing you to control the robot with your PC acting as a master brain. This means you program the micro controller in C, and it acts as a slave to the much more powerful computer's demands. You can then program the robot in essentially any language - from C++ to Python to Scheme (I really don't recommend the scheme).

If you are willing to spend anywhere from 60 to 300 dollars, you can get a powerful ARM development board or single board computer (x86 or other kinds). These you can install and run Linux on, with boot times ranging from a mere 1.6 seconds if you strip down Linux enough. Of course that gets longer as you add modules to Linux. These boards come small enough for the chassis you are mentioning - and allow you to have more powerful programming languages and software being ran on your robot. If you are looking to build a robot that will begin to enter the realm of computer vision, mapping, and high level of human/computer interaction, then this is the route to go.


In both the micro controller and Linux versions I mentioned, SD cards are a possibility. It is far easier, however, in Linux as it does not tax your system as much to read and write to it.

I hope this answer helps!

Offline PyroTopic starter

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Re: New to robotics; Lots of questions
« Reply #2 on: September 05, 2009, 12:15:30 AM »
Thank you very much for your suggestions!  That was a lot of help.  I left out a bit of information, I was in a rush to get out the door!

You answered quite a few questions (even some I hadn't asked yet!), so thank you again.

The single board computer sounds like what I need, as I would like to eventually expand into some more complex things involving various sensors, etc.

Another thing I'm curious about, as I'd still like to make some of my own things, I assume that there are output headers on the single board system, allowing me to attach "expansion cards", such at motor controllers, etc.?  If so then i could at least make some of/all the expansion boards myself :)

As for what I'm wanting to learn, just a bit of everything.  I like learning, so any knowledge is worthwhile!

Thank you for your help, it's hard to know what to ask when you know so little about what you're asking about!  But I'm already learning :)

P.S.:  Any single board computers that you'd recommend?  Cost is really an issue here, so I'd prefer the more inexpensive options :)
P.P.S.:  Would it be worthwhile to do something similar to this tutorial: http://www.societyofrobots.com/member_tutorials/node/26 .  That boasts saving money, as well as the satisfaction of making it yourself :)
« Last Edit: September 05, 2009, 01:13:50 AM by Pyro »

Offline Half Shell

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Re: New to robotics; Lots of questions
« Reply #3 on: September 07, 2009, 09:31:17 PM »
Quote
Another thing I'm curious about, as I'd still like to make some of my own things, I assume that there are output headers on the single board system, allowing me to attach "expansion cards", such at motor controllers, etc.?  If so then i could at least make some of/all the expansion boards myself Smiley


Many development boards for single board computers will have headers you can wire from if need be. And yes, depending on the SBC, you can build a nice little expansion board for it. I created an educational robotics board that connected to a small ARM9 development board via its GPIO header, breaking out much of it's IO to a breadboard and easy-to-prototype space. It's possible, and not hard once you figure it out.

Quote
P.S.:  Any single board computers that you'd recommend?  Cost is really an issue here, so I'd prefer the more inexpensive options Smiley


Assuming you desire an SBC that can run Linux, I like the looks of the Beagle Board. Ridiculously low on power consumption, with a good community and lots of features. I haven't been able to play around with it yet though. I've worked with some of Technologic System's stuff (embeddedarm.com) for some intense projects - I give them mix reviews. If you call in for tech support though you WILL get an engineer that actually designed the board who is quick to help (as long as it's a real technical question), so I give them an A there at least. The board I've spent the most time with from them is the TS-7800 - much more expensive overall.

There are still more, some that you can even find on new egg. Just do some google searching along do it yourself project sites, and see what kind of SBCs are used in those projects.

Quote
P.P.S.:  Would it be worthwhile to do something similar to this tutorial: http://www.societyofrobots.com/member_tutorials/node/26 .  That boasts saving money, as well as the satisfaction of making it yourself Smiley
Quote

That is a cool tutorial, and great if you want to learn how a micro controller works and build one. Do not let my advice stop you from doing that tutorial, as you got nothing to lose from it.

HOWEVER, I recommend you learn C (if you don't have a good handle on it already) and try to learn either the PIC or AVR 8 bit micro controllers. These two brands of chips are very, very powerful, cheap, and can provide a great set of features designed to make your life easier. The Admin's famed Axon is made using an ATMEGA644p, I believe - an AVR chip. Of the two, AVR is, in my opinion, much easier to get started in.

For 80 dollars, you can purchase an STK500, which will allow you to program all of AVR's 8 bit chips available in a DIP package. This is not much more than the 60 dollars you were talking about spending before, and a great investment if you are going to follow this. While I have recently had this programmer stolen, I also have built and used the USBtinyISP:
http://www.ladyada.net/make/usbtinyisp/
It is a 22 dollar kit and can program all ATMEGA chips, and I can at least confirm it can program the ATTINY45 as well It might do all 8 bit AVRs, but I'm not sure. It isn't difficult to put together, and can get you started as well. The annoying part is having to wire up or build a target board for each micro controller.

Offline Admin

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Re: New to robotics; Lots of questions
« Reply #4 on: September 09, 2009, 05:43:15 PM »
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The Admin's famed Axon is made using an ATMEGA644p
ATmega640 ;D


Pyro, all I can say is, read through all my tutorials, watch all my youtube vids (at least all that look relevant for you), and it'll start to make sense.

The $50 Robot is a great beginner project. Or you can just buy off the shelf, like my Axon, and not bother with the low level details. Depends on what you want to do!

Offline PyroTopic starter

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Re: New to robotics; Lots of questions
« Reply #5 on: September 10, 2009, 06:07:22 PM »
Alright, thanks a lot everybody for the help.  I'll be sure to ask if I have any more questions (you guys are helpful :D).

Offline radhoo

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Re: New to robotics; Lots of questions
« Reply #6 on: September 14, 2009, 03:28:52 AM »
Alright, thanks a lot everybody for the help.  I'll be sure to ask if I have any more questions (you guys are helpful :D).

Definitely go for the "$50 Robot project " . It helped a lot of people including me.

Building a first robot requires bypassing two major obstacles:
1) how to build the platform (be it 3 wheels, 4 wheels, tracks, etc), including the motors and the complete propulsion.
2) the robot's brain (either you use a simple microcontroller like Atmega8, or an advanced mini-itx, or pc board).

Not to be redundant (the $50 robot already covers both), but for the sake of diversity here are my solutions:

- for platforms, I've tried to build a few, the main requirement was power : the platform to be able to bypass rough terrain, etc. I've opted for differential control and came up with the following:
Two-wheels robot: Twinmotion, http://www.pocketmagic.net/?p=520 (bottom of post)
Four-wheels robot: Ara , http://www.pocketmagic.net/?p=789
Modified Ara platform (one motor to each wheel), as used in my latest robot Perseus 3: http://www.pocketmagic.net/?p=869
As you can see I'm using geared motors that offer a lot of trust to the cost of RPM's.

- for brain/control unit, my first approach was a PC board with a LPT1 port for controlling external motors (I knew nothing about Microcontrollers at that time).
Then I;ve tried to use a mini-itx board, but the batteries required were to heavy and lasted only a few minutes.
Finally I've found a good compromise between Processing performance and Power consumption/Weight by using a microcontroller for low level stuff (like sensors or motor control) and an embedded processing unit (a smartphone), for the high level programming and unit control. See Perseus 3 for this.
Basically you can only use microcontrollers (see the $50 Robot, for me it was even cheaper :) but I didn't stick to the exact instructions).
Here are my research logs of when I did my first steps with MCU's including the tools I've used, might help you:
http://www.pocketmagic.net/?tag=microcontrollers (go from bottom to top).

Hope this helps. Looking forward to your first project!

[youtube]WnrERopbXD8[/youtube]

Good luck


Offline PyroTopic starter

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Re: New to robotics; Lots of questions
« Reply #7 on: September 16, 2009, 07:07:04 PM »
Thanks for your input radhoo.

I can't seem to find prices on SBC's anywhere (with the exception of one website).  Is there a place with a large variety of SBC's that actually displays prices? ??? That's somewhat of an important deciding factor for me :)  Thank.

Offline PyroTopic starter

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Re: New to robotics; Lots of questions
« Reply #8 on: September 20, 2009, 03:20:12 PM »
Well I've found a few little platforms that may work for me.  I've decided to drop the Linux idea as of now, and just getting a good beginner board for me to fool around with, until I get better at programming, and have a better idea as to what I want to do.  The platforms I've found are as follows:

ET-STM32 Stamp Module     - $24.90
ET-ARM Stamp Module     - $27.90
ET-AVR Stamp Module - Upgraded     - $19.90
AT89C51ED2 Controller - Upgraded     - $24.90
ARM2103 Controller     - $24.90

Keep in mind that I'm a beginner, and I just need something inexpensive that's moderately powerful, and it will eventually be replaced by a more expensive SBC.  So which of these would be the best option?  If none, what is there that would work and is in that approximate price range?  Thanks :)

 


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