Hey guys! It's been a while, but the snow is back and my garage is too cold to be working on motorcycles, so back to the robot projects!
I've been stashing stuff away for a little while for this one, so I might as well let the cat out of the bag and ask for some help. The way I work is that I am easily able to come up with crazy mechanical ideas, but maaaaaaan do I suck at electronics.
Right now I am trying to figure out what to do with the guts of my base, which is a 21st century toys Stuart 1/6 scale tank. The thing runs off a 12v 7.5A battery, and is RC. My plan is to use the track setup as a platform for messing around with large (and frankly probably dangerous) scale robotics to do things like mow my lawn, sweep snow, pick up dog poo, etc.
So today I was cooped up with a massive chest cold so of course I used the time to start taking the thing apart to see what my options are for driving the motors and controlling the thing. When I opened it I found the 2 dc motors with gearboxes running the tracks, and from there the motors were connected to a small board with the 12v input, what I can assume were crappy speed controllers, and then connected to the receiver board.
My options are to run the tank base using the old electronics, which turn the tracks at single speed, and which also means trying to figure out where to control from, being either prior or after the receiver board (no idea on what voltages are running where yet), or just ripping everything out and starting from scratch.
I think I want to start from scratch... too bad I don't know what I'm doing!
My plan right now would be to either get a t'rex controller or "Cytron 13A, 5-25V Single DC Motor Controller" which is dirt cheap (but I would need two) for the tracks, and then have a seperate powered setup for any attachments like a mower, etc. Everything could then be run off of the EZ, but it would be nice to also set up an RC override with FPV for fun.
I am looking at using a battery powered mower I have for the attachment, which runs off a pack with 2x 12v10A batteries in it. This will be on a separate system, since I have no idea how to connect all this together without blowing something up.
Any advice on motor control boards or anything else would be much appreciated! Has anyone ever done a project like running a large power attachment off a bot? I can post pics if anyone is really interested in looking at a bunch of disassembled junk as well.
Thanks in advance!
Other robots from Synthiam community
DJ's Vision Tracking Robot
Khanflicks's Minion Project - Help With Eyes / Mouth
No question about it. You gotta use a Sabertooth. Completely indestructible, easy to control through the Uart port and is supported by EZ Robot. Lots of support here on the forum also. You can set it up to receive RC or let EZB control it. It's a little expensive but you get what you pay for. Here's one that will handle 12 amps per motor but you can get them that will handle all the way up to 60 amps. It will control 2 motors and perfect for what you're wanting to do.
Sabertooth2x12
Thanks Dave,
Yeah, I was considering the Sabertooth, and wow does it have a lot of cool options like being able to hook up and power the controller directly, although not knowing much about electronics the recharge thing kinda has me worried that I would somehow pooch my battery or even the controller. I hadn't noticed the additional servo capacity off of it though, which seems neat.
The reason I was looking at the t'rex ( https://www.sparkfun.com/products/12075 ), was that it was rated for 18A, but it seems like the reviews for it really suck, so I dunno...
Obviously the reason I was looking at that other driver board was that it was so damn cheap.
The more I read about it, I suppose the Sabertooth might be the one I actually end up getting. The expensive FPV setup might just have to wait until after I have rallied local investors who will be shocked and amazed at the versatility of my blow/whack/crap picker. This thing practically names itself!
Anyone know of any other options? Do they make such thing as a 3 or even 4 brushed motor controller, running in these higher amperaged/voltages? I suppose that cost would be outrageous for something like that in a single package.
Has anyone tried any of those cheaper Hong Kong or China boards available on Ebay? Why doesn't EZ-robot sell stuff for applications like this? Lol.
I repurposed a Sherman tank using the Sabertooth 2x5. They make 25, 50, and 60 Amp versions. I put an amp meter in-line with the motors to see how much they pulled under load. With 10lbs of weight, they pulled 3 amps, so I felt the 2x5 should be good. I added a thermistor and small fan to keep it cool, just in case.
Here's the link if it helps. http://www.dimensionengineering.com/products/sabertooth2x60 https://synthiam.com/Community/Questions/1430
Dave l.
Yeah, I checked out your build Dave, and that looks great! I bookmarked the thread as reference too...
Unfortunately I think the beast that I picked up for $50 is a bit bigger than the tiger you used, mine is about 2' in length and 1' wide, and according to a couple of other write ups I found on the net the amperage on the motors may spike to up to 20 at points. So far the 2x12 that Dave S mentioned might be the best fit, but I am still trying to figure out what to do with the power attachment that will run the blower/reel/sweeper I am going to come up with. At this point I think it's just going to come down to yet another high amp driver board. This thing is going to be pretty heavy the way it is going.
I'll put up some pics soon.
A servo can always be used to flip a switch or two if the attachments just need to turn on or off with no speed control. No reason to have expensive speed controllers to just turn the mower deck on and off. I think I have the same tank you have. One of mine tanks wont reverse anymore under RC control, so it will be used for a rover type outdoor robot when I get another EZ Robot board and some warmer weather.
I hope you post some pictures of your build.
David Mc (Seems to be lots of Davids building robot!)