Are there controllers to separately control 2 wheels, like a skid steer?

Do It Yourself (DIY)
1

I want to build a vehicle that has 2 rear motors with steering control like a skid steer.
I am wondering if anyone makes and sells a controller for this purpose or if I would have to buy 2 controllers and wire them to separate levers sorta like a skid steer?

I am looking at a small vehicle weight ~3-400 lbs and top speed ~4-8 mph, I was thinking of 2- ~500 watt motors at 36V w/6 6V deep cycle batteries (~300lbs alone)

I know I can build the vehicle and could control it with 2 controllers easily, however it would be nicer if there was a Controller that was made to do this so there could be just one input.

Anyway just a shot in the dark wondering.

~Sean

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Sorry what is skid steer?

If it is to steer by changing speed of tires a very over looked idea is to use non-bike parts -
gyros ($30) in line with the two speed controls ($60 each) will actually provide traction control and assisted spin out control.

It saves needing to add steering it is just 4 wheels pointed straight.

To see the parts I am talking about check out the propeller driven bike.
It was made specifically to show these parts. They will work with lead acid batteries if you want to churn my stomach :slight_smile:

http://www.evforum.net/forums/showthread.php?p=5334#post5334

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skid steer is tank drive…

each side moves front and backwards to drive like a tank… like the skid steer excavators.

And the issue with skid steer, is that controllers themselves do not do rapid changes in forward or reverse direction. They have to use contactors. You’re not supposed to change “direction” while the motor is in motion, or your contactors will fail.

You might want to look at sevcon and a sepex motor, they can rapidly change direction, but I don’t know if it’l handle your needs.

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skid steer is tank drive…

each side moves front and backwards to drive like a tank… like the skid steer excavators.

And the issue with skid steer, is that controllers themselves do not do rapid changes in forward or reverse direction. They have to use contactors. You’re not supposed to change “direction” while the motor is in motion, or your contactors will fail.

You might want to look at sevcon and a sepex motor, they can rapidly change direction, but I don’t know if it’l handle your needs.

Interesting I would prefer an electronic solution but perhaps I would be $$ ahead to just use a mechanical solution. (just lost efficiency right?)

I was aware that I wouldn’t want to reverse the direction with the motor still spinning but I was hoping there was a controller out there with reversibility in the design. Any ideas on one from another intended use that would work?

With regards to Outrunner I already built a bottom bracket drive E-bike… but haven’t found any lithium batteries I can afford yet… With 24v (2 12v 18AH SLA) I had ~25 miles range and 20-26mph speed.

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[QUOTE=oregonbolens;5340]Interesting I would prefer an electronic solution but perhaps I would be $$ ahead to just use a mechanical solution. (just lost efficiency right?)

I was aware that I wouldn’t want to reverse the direction with the motor still spinning but I was hoping there was a controller out there with reversibility in the design. Any ideas on one from another intended use that would work?

With regards to Outrunner I already built a bottom bracket drive E-bike… but haven’t found any lithium batteries I can afford yet… With 24v (2 12v 18AH SLA) I had ~25 miles range and 20-26mph speed.[/QUOTE]

Contactor option is not really an option, you’ll be replacing contactors left and right. they’re not made to switch under heavy loads, which you will do with a skid steer.

Also, its a pretty specialized design, there just aren’t many vehicles that need to go front and back quickly like a skid steer.

You could forgo reversing quickly and just use forward only steering… and only switch to reverse if you need it… but there IS a delay, you can’t just jam it into reverse.

What kind of power levels/size of vehicle are we talking?

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[QUOTE=frodus;5342]Contactor option is not really an option, you’ll be replacing contactors left and right. they’re not made to switch under heavy loads, which you will do with a skid steer.

Also, its a pretty specialized design, there just aren’t many vehicles that need to go front and back quickly like a skid steer.

You could forgo reversing quickly and just use forward only steering… and only switch to reverse if you need it… but there IS a delay, you can’t just jam it into reverse.

What kind of power levels/size of vehicle are we talking?[/QUOTE]

I think having them have to stop before reversing would be totally fine for my application. As this would be normal operation mode, probably build in an ■■■■■ switch so it wouldn’t even do it.

I am looking at more of a ZTR mower application with 2 small motors in the rear for each wheel separate controllers allowing for no steering linkage and ability to use casters over a deck. (Another DC Motor running 1-1 ratio with just a contactor/solenoid)

I am looking at a weight of ~50-150 lbs before motors batteries, rider, etc. I think I can do >500lbs without rider probably 700 loaded, but geared way down should be able to run on 500W Motor per wheel or even 350W. This would Leave me enough power to run for an hour I figure.

Anyway I want to do this really cheap with chinese DC brushed Motors for now what controllers should I look at for cheap easy to reverse action.

I am hoping I can wire up a switch that reverses the polarity when pressing a lever past a “center” point and up to that point it is a rheostat that is higher speed the further from the “center” it gets. I think I can engineer it with relays and some crazy levering system.

Anyway Frodus you are pretty local I would love to swing by and check out your shop sometime I hear you have an E-motorbike you are working on I have one for a someday project sitting outside…

I am up in portland most thursdays…

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You’re welcome to swing by. I’m in PDX in Northwest at the EV shop (Synkromotive) on Tues/thurs and Saturdays.

www.evfr.net is my bike/blog.

It sounds like you should be able to do this project, but what kind of range (in miles) are you looking, is it just a recreation vehicle for your yard? or something to drive in the neighborhood/streets?

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[QUOTE=frodus;5371]You’re welcome to swing by. I’m in PDX in Northwest at the EV shop (Synkromotive) on Tues/thurs and Saturdays.

www.evfr.net is my bike/blog.

It sounds like you should be able to do this project, but what kind of range (in miles) are you looking, is it just a recreation vehicle for your yard? or something to drive in the neighborhood/streets?[/QUOTE]
Where in NW is your shop located?

My Company’s main office is in NW just near the Fremont bridge, I am up there regularly.

I am looking for more of a range of 3/4-2 acres on a charge, thinking I will use 6V deep cycle batteries series to 36V. Then have 2 Deck motors ~1000W each (just on off no controller), and two drive motors 350-500W. Figuring I want to be able to mow at 5mph with a 40" mowing width. Looks like I will need about 2 hours worth of charge…

I am going to start looking for a frame to start from on this project, hoping that I will not have to build one from scratch. But my goal is to have a working nice prototype before 2010. (from my garage…)

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2 Hrs at 5mph sounds doable…might not be differential stearing, but more like a tail drag mower (stears in forward only, but motors won’t reverse). If you need reverse, you can switch to reverse.

sounds like you want something like these:
http://www.robotmarketplace.com/products/speed_controllers_main.html

they’re controllers for heavy robots, and alot of people use them for etek motors… have a look and see if they’re reversing.