6 Wheeled Robot - Differential Steering

Alright, so I will connect the H-Bridges to the Arduino, and the batteries and motors to the H-Bridge?

doctorflash:
Alright, so I will connect the H-Bridges to the Arduino, and the batteries and motors to the H-Bridge?

Yes. Your h-bridges - depending on what you buy - will likely offer different modes of operation; the better ones will offer R/C mode (use the Servo library to command them - easy-peesy), TTL serial mode (some also offer full RS-232, USB, and sometimes ethernet), or PWM mode (which will be a couple of pins you supply PWM signals to - one to drive the h-bridge "forward", the other "reverse").

If you are building all of this - or have built it - I trust that you do understand that your h-bridge controller will need to be very powerful, and thus will likely be very expensive...

Also - you may want to rethink just driving two wheels on a side - you'll likely have much better luck running all three wheels at once on a side...

doctorflash:
Great! This is more information than I have found anywhere. Thanks a lot!

~million hits, very common robot platform.

https://www.google.com/search?as_q=DIY+skid+steer+robot+&as_epq=&as_oq=&as_eq=&as_nlo=&as_nhi=&lr=&cr=&as_qdr=all&as_sitesearch=&as_occt=any&safe=images&tbs=&as_filetype=&as_rights=

Try this H-bridge: the L298, made by ST. It's dead simple to use and not very expensive (~$5 or so).

cr0sh:
Also - you may want to rethink just driving two wheels on a side - you'll likely have much better luck running all three wheels at once on a side...

Planning on putting gears on front and back to make it 4WD. Would that work?
And would that L298 motor driver work for my purposes? To clarify: I am only using two 12V batteries total, even though the motors are 24V. Not sure on amps, but probably peaking at 35ish.

oops, no way then, the L298 is only good for 4A...

I'd have a look at the Polulu high current H-bridges, probably upto handling a wheelchair
motor at half voltage. Something like this: Pololu Dual VNH5019 Motor Driver Shield for Arduino (ash02a)
seems appropriate. Note that forced-air cooling of the motor driver board is assumed for those
current levels. The chips used are actually multiple discrete MOSFETs and a controller chip mounted in
a single package, about the neatest solution for a power H-bridge there is.

That looks more like it. Even though it's peak is only 30, do you think that'd give me enough headroom?
And is it easy enough to use?

You would be better off at the full 24 volts. Higher voltage means lower current at the same power.

You can also connect both outputs to a single motor which doubles the current rating. You would then need 1 board per motor.

Okay. So it looks like I need to solder the motor wires directly onto the board.
Do you know where I can find an RC remote with the sensor, and where it would go on the Arduino?

Discussion on a fairly high powered inexpensive H-bridge.

http://forum.arduino.cc/index.php?topic=148482.0

http://www.ebay.com/itm/Double-BTS7960B-43A-Motor-Driver-High-power-module-smart-car-driver-For-Arduino-/221235721147?pt=LH_DefaultDomain_0&hash=item3382ad33bb

Do you know where I can find an RC remote with the sensor, and where it would go on the Arduino?

Do you mean Radio Control or a TV style IR Remote?

If you mean IR, here is what I use with robots. Notice the small handheld remote on the same page.

I use this library: A Multi-Protocol Infrared Remote Library for the Arduino

Radio control. Similar to this: http://site.rctoyz.com/rideon-car-remote.jpg

Would this work if I remove the sensor? (Or whatever it's called that picks up the signal).

RC controllers are normally used with RC Receivers. The Receiver then controls motor ESC's and servos. The ESC is somewhat similar to a motor control board but not identical. Putting an Arduino in the loop is possible but a bit convoluted.

Are you trying for remote control, autonomous control or some mixture of them?

Here is an interesting tutorial with followup comments: RC Hobby Controllers and Arduino - SparkFun Electronics

I want it to be remote controlled, but just to start out with. Eventually fully autonomous.
Could I use the parts from that car?

Could I use the parts from that car?

Probably not. In any case, all RC boxes work the about the same differing in # of channels, range etc.

You should start with something inexpensive like this kit. I am not recommending this model just using it as an example.

The little black box receiver 6 outputs must then be read and interpreted by the Arduino. This only makes sense if you intend to move toward semi-autonomous or fully autonomous operation. Otherwise the Arduino is pointless and direct RC control easier.

If you search this forum you will find others who have done similar projects. I'm no expert on RC systems.

Would that automatically do differential steering? Because I already bought the Arduino and $50 motor controller that connects to the it... can I still use those for something? Maybe once I go autonomous?

[I already bought the Arduino and $50 motor controller ](http://I already bought the Arduino and $50 motor controller)

You should use them. The Arduino will interpret the RC commands and perform the differential steering thru the motor controller you purchased. I was just pointing out that the system could be built without the Arduino but with no independent abilities. The Arduino allows you to evolve the system over time.

Oh, great. I was worried. Thanks so much for all of your help!