Arduino Forum

Topics => Robotics => Topic started by: BlueJakester on Aug 29, 2012, 11:06 pm

Title: Researching first chassis, or suitable donor RC Truck
Post by: BlueJakester on Aug 29, 2012, 11:06 pm
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://i264.photobucket.com/albums/ii180/5e3/Micro/635_Tank-style.jpg)

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? (http://www.pololu.com/catalog/product/61) Here are general specifications:

(http://i264.photobucket.com/albums/ii180/5e3/Micro/tamayispecs.jpg)

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
Title: Re: Researching first chassis, or suitable donor RC Truck
Post by: Sandeep_Raj on Aug 30, 2012, 12:19 pm
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..
Title: Re: Researching first chassis, or suitable donor RC Truck
Post by: DuaneB on Aug 30, 2012, 12:30 pm
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 (http://rcarduino.blogspot.com)
Title: Re: Researching first chassis, or suitable donor RC Truck
Post by: BlueJakester on Aug 30, 2012, 04:18 pm
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?
Title: Re: Researching first chassis, or suitable donor RC Truck
Post by: dxw00d on Aug 30, 2012, 05:06 pm
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.
Title: Re: Researching first chassis, or suitable donor RC Truck
Post by: DuaneB on Aug 30, 2012, 06:23 pm
Look up delta robots, thats how they work - should really build one myself.

Duane B.
Title: Re: Researching first chassis, or suitable donor RC Truck
Post by: DuaneB on Aug 30, 2012, 06:33 pm
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
Title: Re: Researching first chassis, or suitable donor RC Truck
Post by: BlueJakester on Aug 30, 2012, 06:41 pm
Yes, SparkFun has a two-wheel w/caster chassis they call Magician (https://www.sparkfun.com/products/10825) which is $14.95:

(http://i264.photobucket.com/albums/ii180/5e3/Micro/magician-chassis.jpg)

They sell this Ardumoto shield (https://www.sparkfun.com/products/9815) 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.
Title: Re: Researching first chassis, or suitable donor RC Truck
Post by: keeper63 on Aug 31, 2012, 06:31 am

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
Title: Re: Researching first chassis, or suitable donor RC Truck
Post by: Riley-NZL on Aug 31, 2012, 07:36 am
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.
Title: Re: Researching first chassis, or suitable donor RC Truck
Post by: BlueJakester on Aug 31, 2012, 12:34 pm
Thanks for the continued advice. I haven't bought anything yet but am collecting a lot of good information and forming ideas.

Jake
Title: Re: Researching first chassis, or suitable donor RC Truck
Post by: BlueJakester on Aug 31, 2012, 07:01 pm
The Dagu 5 looks like a good way to get started. I read Nick Gammon's thread on the Dagu 5 (http://arduino.cc/forum/index.php?topic=82618.0) with great interest.  I think the encoders would be useful. Definitely an option.
Title: Re: Researching first chassis, or suitable donor RC Truck
Post by: Sandeep_Raj on Aug 31, 2012, 08:22 pm
Here is the chasis which I made. (http://C:\Users\Sandeep\Desktop\32233_119959878028888_3469524_n)
Title: Re: Researching first chassis, or suitable donor RC Truck
Post by: Sandeep_Raj on Aug 31, 2012, 08:27 pm
(http://i46.tinypic.com/1zm02ue.jpg)
Title: Re: Researching first chassis, or suitable donor RC Truck
Post by: BlueJakester on Aug 31, 2012, 09:07 pm
Thanks for posting the photo Felix. What did you use for motors and did you build your own motor controller there?
Title: Re: Researching first chassis, or suitable donor RC Truck
Post by: Sandeep_Raj on Aug 31, 2012, 10:10 pm
I purchased those 2 geared motors and the tyres. The front part has a skid (omni directional). The circuit board over there has a L293D driver IC and a slot for the Atmega 328. All I have to do is burn the code and place the Ic in the board. To make it function, it costed me around 15$. This is a line follower, I used LED and LDR array to make it move.

My opinion is, save the 30$ rather than using it on a chasis, and invest them on some sensors. There are some coll stuff out there. Sculpt the base, make some space for your sensors in it, and they will do what you want them to...  ;)
Title: Re: Researching first chassis, or suitable donor RC Truck
Post by: zoomkat on Sep 01, 2012, 12:23 am
You can use servos modified for continous rotation as drive motors and use cheap materials like below to make a simple bot.

http://www.lynxmotion.net/viewtopic.php?f=20&t=6343