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Shevek
06-16-2009, 09:38 PM
Ok, so I have a small to medium size rover project coming along, and I have some questions, If anyone can help. I'll post pictures for reference, along with pictures of my other projects, soon. So the robot is about 2.5' by 2', and uses a pair of power wheels motors with machined hubs that have sprockets bolted to them. The sprockets connect bicycle chain to two wheels per motor, two sprockets per hub. This gives the robot a general tank-style control, and now I'm thinking in terms of control. I'd like to avoid the use of a microcontroller, as I've done all of my other projects with BS2's and autonomous navigation, and I want to make this manually controlled. So I was thinking of a simple circuit with a pair of solid state relays that I have to switch between forward and reverse for each motor, thereby creating a rudimentry control method. I think I've worked out how to wire this, although any glaring concerns that you guys see would be appreciated, as I'm new at this :) My question, therefore, is what about wireless communication? I would like to make this thing wireless, but I am working on a tight budget, like most of us. This also doesn't have to be exact, it's more just a thing for fun, going forward/reverse and turning while 20 feet away would be great. I've seen some of the bluetooth options, but they all seem to require at least microcontroller support, and are rather expensive generally. If I need a microcontroller, so be it, but I figured there might be an electronics solution to bypass that for simple control. I can also do some decent electronics work, as in building some more complicated circuits and/or a remote control for the thing. Sorry If I missed any crucial points of information needed to help, or if I'm too vague, I'll update with any info you guys deem necessary. Thanks for the help! :veryhappy:

Adrenalynn
06-16-2009, 09:54 PM
Welcome to the forum!

I'd suggest XBee and a simple HBridge controlled via an AVR micro.

I'm moving this thread over to I/O Boards. Again - welcome!

Shevek
06-17-2009, 03:30 PM
Thanks for the help. An H-Bridge was pretty much exactly what I had in mind in terms of electronics, and the XBee seems to be the perfect solution :)

robologist
06-18-2009, 09:51 AM
Here's a possible solution to bypass a micro :
http://cgi.ebay.com/4-CH-RF-Wireless-Remote-Control-Momentary-Toggle-Latch_W0QQitemZ350212808902QQ
The relays are probably a little light to control your power wheels motors, but maybe you could pair them up, or solder in something heftier.

Adrenalynn
06-18-2009, 11:25 AM
Have you tried those yourself? I bought two from them, and a handful of different ones from another eBay seller in China - they stunk-on-ice. Not even 50% reliable within a few feet... If you've tried 'em and they've worked for you, I've just had a couple dozen bad ones - actually entirely possible with the quality [un]control on those things.

Orac
06-18-2009, 01:10 PM
I must be lucky as I've not had a problem with mine ...yet

Adrenalynn
06-18-2009, 01:17 PM
So what kind of range are you getting - and is it that one specifically? What are you using it to control?

robologist
06-18-2009, 03:13 PM
Have you tried those yourself?

Can't say that I have, but have wanted to on several occasions. I actually wanted a unit without the relay board, just a couple channels to send a short range signal. Since it was mentioned in the OP that the range should be 20 feet, I figured that would be about the performance of this item, similar to a car remote. Ebay does have feedback that can be used to complain on performance issues if there were a major problem with this.

Alternatively, a cheap Futaba or other RC radio could also be used get a little further range, kicking a relay or switch mechanically, without resorting to a micro/h-bridge combo. I have a cheap Futaba AM that I've used. ;)

Adrenalynn
06-18-2009, 04:19 PM
yeah, or one of those PWM "battle switch" relays

Shevek
06-18-2009, 06:55 PM
yeah, or one of those PWM "battle switch" relays

What do you mean?

robologist
06-18-2009, 11:11 PM
Something like this, a relay that operates off an RC servo signal :
http://www.robotmarketplace.com/products/0-BATTLSW1.html

Just plug it into a RC receiver and it should toggle based on whatever controls that channel from the RC transmitter.

Adrenalynn
06-18-2009, 11:31 PM
http://www.robotmarketplace.com/products/rc_interfaces.html

[Edit] Sorry - I didn't see a page2, I still had page-1 cached

Al1970
06-20-2009, 02:21 AM
Hi:

I use a "VEX" transmitter which you can pick up on E-bay for $20 to $30. I send the signal to a PIC which then can control up to 8 motors. There more info on my site.

http://www.geocities.com/robotsandyou/

Al