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Building a Small Autonomous Robot?
Nedward asks: "For Christmas I would like to give a friend all the equipment to build a small (approx 1 ft^3) mobile autonomous robot. I have looked up some kits online, but I would like more freedom than the kits offer (fully programmable, etc). The challenge: I only have $200.00 to spend. Has anyone put together a robot (CPU, motor, sensors and so forth) with that kind of a budget? Any other suggestions?"
Take a look at the Lego Mindstorm kits http://www.legomindstorms.com/. They're in the $180 to $200 dollar range and come with all the parts your friend would need. Plus, there are several choices for programming the Lego Mindstorms programmable brick on both Windows and Linux, including BrickOS, Lejos(Java), and NQC(Not Quite C).
I've built a few robot platforms around the 68hc11 brain, and that chip is the easiest one to get started with:
- 8 bucks each, from any number of suppliers
- Single-chip solution - the only external components are an 8 MHz crystal and 2x 22pf capacitors
- DIP package - fits into Radio Shack solderless breadboards nicely
- It's fast - a whopping 2 MHz
- 256 bytes of RAM, and a 2K EEPROM for program storage
- 16 lines of digital I/O, 8 ADCs, input compare and output compare timer lines, 2 serial ports, and a few other nicities
You can download code to it over the serial port (and write it into the EEPROM), with the addition of 1 more chip - a MAX232 serial level converter. Tools for its instruction set (compilers, assemblers, etc) are very easy to find, as are schematics for a basic setup for the chip and for the serial converter. A google search should reveal a BASIC and a FORTH compiler for it, among various other (free) tools.The guys at the Seattle Robotics Society do a lot with this architecture, and they have plenty of articles and links pertaining to it.
Every cloud has a silver lining (except for the mushroom shaped ones, which have a lining of Iridium & Strontium 90)
You might find sumo-related resources helpful or inspiring. Full-size (Japan) scale sumo's are 20cm^2. Mini-sumo (the most popular scale in the US) is limited to 10cm^2. Many of the designs focus on low-cost parts, tricks, etc.
I have a list of some mini-sumo links here
Trusty 'ol HandyBoard
68HC12
Lego Mindstorm
8051 development board
Good 'ol Parallax
There are also chips/development boards from Microchip (manufacturers of PIC series of ucontrollers) and Atmel.
Most of the above DO NOT come with motors, sensors, base, wheels etc. However, these are not difficult to find at a nearby hobby shop.
For a little more challenge, get a DSP board (TI, Motorola, Analog devices etc). You can get a good new/used one for pretty cheap from eBay
http://www.junun.org/MarkIII/Info.jsp?item=1
"This is the complete Mark III Robot kit, everything you need to build a working autonomous robot including controller board, sensors, pre-programmed PIC, chassis, wheels, motors, documentation and software. Just add batteries. Assembly required."
The Handyboard is a favorite of robot hobbiests and researchers. We use them in our Mobile Robotics class at Uni. The full-on Handyboard is about $299, though. A somewhat reduced version of the Handyboard, the Handy Cricket is available for $99 from Gleason Research with a sensor/motor kit included. If you check the Handyboard page, there are several other vendors, including ones that sell unassembled kits for less, if you're not afraid of a little (okay, a fair bit of) soldering.
I recommend using Lego to build the body of the robot as it's highly reconfigurable, cheap, and fun to play with even without the robot parts.
These guys sell a sumo platform (BASIC Stamp powered) for $90. That leaves room in the budget for upgrades. or buy two so they can battle :)
Go to your nearest library (or bookshop if you want to buy it. good reading if you like that stuff) and get a copy of "Robot Builder's Bonanza". It's a big book on how to make small robot projects on low budgets. I got it my self and it's really interesting. The projects are easy to understand and easy to manipulate to your own desires.
The HC11 has been nearing the end of its life for years now. You'd be nuts to use that chip in a new design.
Consider using an AVR chip. Its a nice, modern RISC (32 registers, compared to the shitty HC11's handful). They are much cheaper, have a shitload more memory and peripherals, and tons faster (16/24 MIPS). Even a common-as-dirt PIC chip would be better then this.
The tools are much better for PICs and AVRs because they are much more popular.
Lego Mindstorms can be a great way to start. But it can be limiting. It comes with only 2 motors. It can control only 3 motors and have 3 sensors. The programming environment can be limiting too, but there are other options on the web to help.
If you think your friend would be interested in something a little more complex, I can point you to some other resources...
There are some robot kits on the market. A pretty good one is: SumoBot Robot ~$150
Or you could get a platform and controller board seperately:
Tracked Motorized Platform ~$60
Controllers The OOPIC II Starter package ~$70 is a decient starter
A number of hobby clubs in Colorado like the Atmel Atmega Microcontrollers for building custom robot board such as the DARC Board.
The Portland Robot Group has a lot of great information for people starting out with hobby robotics.
My robot blog with lots of pictures.
You basically have 3 main parts or units for an autonomous robot - the body, the brains, and the sensors. You want to do this cheap, and you want to do this fast. So, start off with the body:
Go down to the Goodwill stores in your area. Look around. See something that can be used for the body? Grab it. Miscellaneous parts? Grab it. Go on 50% off day, all the better. You are looking for things like remote controls, old joysticks, used VCRs and cassette recorders, old radio controlled cars or other similar things (or remote controlled tank devices, etc). I was at some Goodwills these past two weekends, I managed to score 2 old "battlebot" toys (nice battery operated simple tank drives), 1 full direction radio-shack dune buggy, and a complete Star Wars Droid Mindstorms kit (cheesy, yeah - but goes great with my full RCX 1.5 kit) - spent less than 10 bucks (!). You want the remotes for the IR LEDs in them, and the other stuff for motors and gears, etc.
Another possibility (though more expensive) is to get some cheapo toys and such from bargain places (like Big Lots) that will work for a robot body. Don't forget ideas like a piece of 2x2 plywood, a couple of casters, a couple of lawnmower wheels, and a couple of cheap power screwdrivers (all that should be doable under $50.00).
Get him the "Robot Builder Bonanza" book - he will need it and cherish it - buy a used copy for cheap. Don't worry about the condition much, if he likes your gift, he won't care.
Alright, so you got the body - you need the brains. Hopefully, you didn't spend much more than 10 dollars on the body - but no more than $50. And the book should be cheap, too ($10.00 if you bought it used). So, for the brains you need something easy to use - go for a Basic Stamp 2 (Parallax). The hardware is cheap ($40.00), the software is plentiful (even free), and there is a lot of documentation and tutorials online. Interface electronics will be needed - a good pack of resistors, transistors (throw in many NPN and PNP power transistors for H-bridges, too), diodes, capacitors, and some relays and LEDs. Also, add several "glue logic" chips (most won't be needed for the Stamp, but they're cheap, so put some in). Toss in a breadboard, and add a few copper-holed protoboards, too.
Now, for sensors: remember those remote controls from Goodwill - well, there is where you get some of your sensors: You want simple devices for the sensors, so go with IR LED/phototransistor pairs - easy to drive and sense from the Stamp. The remotes and such will have one or more of the IR LEDs you will want (and some of the LEDs, as well). The VCRs, etc that you pick up will also have the receiver units or phototransistors needed (or, just buy some phototransistors). The reason I say get the stuff from Goodwill, is that the parts can sometimes be cheaper to get this way than buying new - but shop around, it may be cheaper to buy many of the parts from say, All Electronics or something.
Throw in some double-sided tape, some corruplast or thin plywood, a pack of screws and/or bolts - and hopefully he (or she?) will have enough imagination to supply to turn it all into a functional robot...
Reason is the Path to God - Anon