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Topic: Researching first chassis, or suitable donor RC Truck (Read 2854 times) previous topic - next topic

BlueJakester

Aug 29, 2012, 11:06 pm Last Edit: Aug 29, 2012, 11:10 pm by BlueJakester Reason: 1
I'm trying to find an inexpensive way to get started with an Arduino controlled robot chassis. I'd like to keep it under $100 for a complete rolling chassis and motor shield. I already have a suitable Uno board, wire, relays, and other misc. parts.

I was pricing out parts and this setup is quite affordable. Less than $30 I think:



http://www.pololu.com/catalog/product/61
http://www.pololu.com/catalog/product/79
http://www.pololu.com/catalog/product/106

I would still need a motor shield and battery pack. I thought I read somewhere that the Tamiya motors were tricky to use; voltage or current draw? Has anyone built something from the Tamiya 70097 twin motor gearbox? Here are general specifications:



My other thought was to buy a "donor" RC Truck from eBay or a store like Target/Walmart. But the choices are so vast I'm not sure where to start off in that path.

Any advice and/or suggestions would be appreciated.

Thanks,
Jake

FelixFelicis

Its cheaper to make a chasis than to buy 1. I used a SMC sheet for the base, made some markings in it, and gave it to a carpenter to cut it out. Depending on what your truck must do, you wont even need a gear box. Get the battery holders and motors, measure their size and design a chasis. bit of work is needed. But I only spent 3$ on it. Its pretty good..

DuaneB

Hi,
   The tamiya tank tracks are fine on smooth slippery floors but will not work on surfaces with grip like carpet, or most outdoor surfaces.

Duane B

rcarduino.blogspot.com
Read this
http://rcarduino.blogspot.com/2012/04/servo-problems-with-arduino-part-1.html
then watch this
http://rcarduino.blogspot.com/2012/04/servo-problems-part-2-demonstration.html

Rcarduino.blogspot.com

BlueJakester

Thanks for the replies.

I'm going to try and find some suitable wheels and motors to attach to a home-built chassis. I have some woodworking tools and can cut up some thin and light pieces to make something. With wheels, as opposed to treads, I suppose have to include some type of steering. Simply driving the wheels in opposing directions won't work, will it?

dxw00d

Quote
Simply driving the wheels in opposing directions won't work, will it?


It can do. That's how BigTraks work. There are some four wheel drives that also use differential steering.

DuaneB

Look up delta robots, thats how they work - should really build one myself.

Duane B.
Read this
http://rcarduino.blogspot.com/2012/04/servo-problems-with-arduino-part-1.html
then watch this
http://rcarduino.blogspot.com/2012/04/servo-problems-part-2-demonstration.html

Rcarduino.blogspot.com

DuaneB

No its not, apparently a delta robot is something totally different - what I meant was the robots with two wheels and a free rolling caster as the third wheel.

Duane B
Read this
http://rcarduino.blogspot.com/2012/04/servo-problems-with-arduino-part-1.html
then watch this
http://rcarduino.blogspot.com/2012/04/servo-problems-part-2-demonstration.html

Rcarduino.blogspot.com

BlueJakester

Yes, SparkFun has a two-wheel w/caster chassis they call Magician which is $14.95:



They sell this Ardumoto shield too, for $24.95. I have a some suitable Uno builds that could serve as MCUs, so I could probably get started with this for less than $50.

cr0sh


My other thought was to buy a "donor" RC Truck from eBay or a store like Target/Walmart. But the choices are so vast I'm not sure where to start off in that path.


This -is- the least expensive method - but you don't buy one off of ebay or at a store...

You buy one from Goodwill or some other thrift store. It typically won't have the transmitter, but you don't care about that. It shouldn't cost more than $10.00 USD ($5.00 USD is the norm, at least here in AZ). You can find them even cheaper during half-off Saturdays.

There is mainly one brand you are looking for - New Bright Toys. Once you find a suitable chassis, you'll want to inspect it to make sure the wheels are all round, that the gearing is still good, that it "sounds" like nothing is broken, and that the steering mechanism seems in good shape.

The majority of the New Bright Toy vehicles use a chipset called the "TX2/RX2" chipset. It is a very, very common and cheap chipset used for creating these el-cheapo RC toys. Many manufacturers have used the chipset and still do (the SMT version is popular today; the DIP thru-hole was more popular in the past). If you do things right, you can use the pinout of the chipset to figure out where and how to control the h-bridges that control the functions of the vehicle.

Want to know more? See this old mega-thread:

http://arduino.cc/forum/index.php/topic,86883.0.html
I will not respond to Arduino help PM's from random forum users; if you have such a question, start a new topic thread.

Riley-NZL

The problem with the Tamiya motors is that they run at 3v with a high current draw (~2amps at stall). Most motor controllers have a minimum of 6v, there are a few for 4.5v. You can get replacement motors from other brands, but that is an added cost.

BlueJakester

Thanks for the continued advice. I haven't bought anything yet but am collecting a lot of good information and forming ideas.

Jake

BlueJakester

The Dagu 5 looks like a good way to get started. I read Nick Gammon's thread on the Dagu 5 with great interest.  I think the encoders would be useful. Definitely an option.

FelixFelicis


FelixFelicis


BlueJakester

#14
Aug 31, 2012, 09:07 pm Last Edit: Aug 31, 2012, 10:12 pm by BlueJakester Reason: 1
Thanks for posting the photo Felix. What did you use for motors and did you build your own motor controller there?

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