Robotics 'half' beginner. Any help appreciated

The base you've selected seems way too small. I didn't notice that they provide dimensions, but as the base is built on Tamiya's Track-and-Wheel set, it's probably around 4" wide by maybe 7" long, Your Mini-ITX board is close to 7" square, and you still have to find room for a 12 volt battery, the DC-DC converter, and any other electronics and sensors. Weight adds up quickly.

Jay Newman, who posts here, has extensive experience with building robots using Mini-ITX boards. Check out his posts. He keeps a blog of sorts of his building trials, and the mechanics he's used. His tracked bases are 4-5 times larger than this one.

Personally, I'd go with a base of at least 10" square, and IMO forget the tracks unless they are rigid. As weight increases, rubber-only tracks can stretch, then pop off the drive sprocket in a turn.

Before buying any hardware I'd suggest:

1. Get a good all-around book on robotics basics. I wrote one, and there are some others, like David Cook's Robot Building for Beginners, and Gareth Branwyn's Absolute Beginner's Guide to Robotics. Thumb through the books at a bookstore to see which one(s) suit your needs. Mine probably has the most about interfacing to PC electronics (though via a parallel port mostly), and I'll say now it's limited to just a couple chapters, because it covers several other electronics approaches as well.

1. Look into USB-serial and USB-parallel converters. You can then buy or build interfaces from these converters, as needed. These are easier to use under Windows, especially if you use a simple DLL in your C program.

2. Bone up on general electronics with a good book, or use Google to find the *numerous* Web page tutorials. You may only have one or two questions now, but as you get into this, you'll have dozens, and it's just better to educate yourself first with the basics.

1. Keep doing lots of searches on Google to see what others have done. It'll save you lots of time in not reinventing the wheel. More and more folks are using Mini-ITX boards for robots. Check out VIA's Web pages for their robot initiative stuff. They include some links to companies trying to make this approach commercially viable.

2. And most important: start with a low-cost (0-150) basic robot kit that is programmed using a microcontroller. Get some experience with the smaller form factor. You may want to get a controller you can program in C. Check out Brian Dean's MAVRIC boards at bdmicro.com. His are based on the Atmel AVR chips, which can be programmed using free versions of C (gcc, and several others).

-- Gord> I'm a software developer delving into robotics, something I've always

Sounds like you've got a good handle on the number cruncher for your robot. I'm about to buy an ITX board for my web-controlled robot.

You will need to get into microcontrollers for motor control, sensor feedback, etc. I prefer PICs

I plan to interface my ITX board to my main PIC with RS232 serial comm.

BRW

Then is is best to use ready made circuits that come with instructions how to control them from your software.

Resistor (brake pads) voltage (accelerator position). This would be like controlling your cars speed by applying the brake without releasing the accelerator pedal. There are circuits that will drop the voltage efficiently. No major loss of energy in the resistor (brake pads).

Gordon, thanks for taking the time to reply. All comments are very useful.

Hi John

Thanks for your reply. Do you have any info on 'recommended circuits' ?

Hi Bennet. Thanks for your reply

I have read about the 'PIC' controllers. I understand you have to write code for them and load this code onto the chip. However, as I already have a 'brain' (My ITX board), do I really need to get another smaller 'brain' to control the robot. Can I not do this direct? Any comments greatly appreciated.

Likewise for the most part.

OK, I have the M10000 and PW60, but I run Gentoo Linux on it. I like to use Java for robotic control.

I think that this base might be a bit small for the Mini-ITX system.

Zagros Robotics makes some bases that are large enough.

I warn you that batteries are either going to be heavy or expensive.

You'll also need some sort of I/O processor for dealing with real-time systems (motors, sensors, etc.).

Phidgets have some interesting USB devices.

If you don't want to build your own H-Bridge, you can use R/C Electronic Speed Controllers. You'll still need a device to sit between the computer and the motors/sensors.

You can try the motors at 12 V. Sometimes you can use extra voltage safely.

One thing I've learned: if the motors you have don't work, it's often cheaper to buy new motors.

-- D. Jay Newman

Well, yes. However, it doesn't seem that Walmart carries that

Agreed.

Gordon's _The Robot Builder's Bonanza_ is still the bible for this hobby.

I don't think that they are shipping yet, but White Box Robotics are made for the Mini-ITX boards.

I second this. It will be much less expensive and you'll be up and running faster. You'll also get experience with the basics.

-- D. Jay Newman

The PIC will give you some very important things that the PC cannot. For example: Dual PWM output for variable speed motor control Extremely fast I/O control - e.g. determine distance and speed from an encoder and control the motor with a PID loop. Accurate time measurement and generation.

After you get some experience with robotics, you will see that the above things are very important.

BRW

Thanks Jay and for everyone else for taking the time to reply

Yes I have just purchased a 12v 7.2ah battery. 2.5Kilo is a hefty lump! And I imagine that even this may not run things for too long. I've bought an ammeter just learned how to work out how to use it to determine current drain! I'm hoping my move to ommit a hard drive and use CF will help things somewhat.

I've had a look at Zagros Robotics. Very interesting, and I'm starting to think that a robot without tracks may be the answer for my first attempt. (Shame as I think the tracked robots look very cool, is there not an alternative tracked kit someone can recommend? Perhaps with many levels and one that can handle a few kilos of weight without springing off it's tracks :-) ). Otherwise I'll go for a wheeled one.

I looked at

Thanks.

Jay. Do you have a website detailing your experiments? Gordon mentioned a Blog.

Thanks again

No. Sorry rw but I have never used commercial interfaces as I have enough electronic knowledge to cobble together my own interfaces from circuits given in electronic magazines and books.

Also I don't use the latest languages like C# and have been limited to using C, BASIC or Assembler with DOS for my PC based robot projects.

John

Also, Gordon, I like the look of your Octobot II. Very good value, and I'm thinking with it's multilevels, I might squeeze my ITX on one level, and battery, camera and sensors on the others?

Your thoughts appreciated.

I get a couple of hours from a 9 volt SLA battery. This runs all my electronics.

Qute a bit. I'm mvoing to a 70 amp-hour battery when I go for a real hard-drive.

I will admit that I have to mount some of my development directories via NFS.

I like tracked robots also but as Gordon says, large tracks are non-trivial. The R/C tank I'm using has tracks which are composed of small individual segments.

Yes. I have tested this on one of Gordon's kits, but the PhidgetServo4 only provides power to only a single servo, unless you provide the extra power.

The "blog" is my URL at the end of this post.

-- D. Jay Newman

I don't think that it is big enough.

I have the original Octobot.

There seems to be about a 4 lb payload and your battery alone is more than that.

Plus the Mini-ITX board is 7.5 inches by 7.5 inches aquare and is bigger than the Octobot base.

Now, if you were to get a Nano-ITX board and use higher density batteries you might get it to work.

-- D. Jay Newman

This is correct. The Octabot is suggested at no more than four pounds total weight, and the base itself weight one pound. RW's battery alone is 5.5 pounds.

-- Gordon Author: Robot Builder's Bonanza Budget Robotics:

Thanks again Jay and Gordon.

Ok so it looks like I'll have to lay out some cash and go for the Zargos beast for my first attempt. Better get saving! (unless of course Gordon expands his excellent range for a larger based kit for ITX users? hint hint :-) )

Anyway, I realise you guys are into your linux, but just for info for others I've managed to get win98 on a 512 CF card with 350mb to spare. Check this

Also I think I'll play around with the USB stuff and grab a copy of Gordons book.

I enjoyed reading your blog Jay, good luck with Stuart. I think a tracked vehicle may be a my second or third robot perhaps?