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larkinja
larkinja is offline
#91
Feb5-10, 09:46 PM
P: 63
Wondering if you have time for an offshoot question?

I think I am going to use an analog driver card to control the pump. I've been working with the card engineers to figure out the current ratings and such, its got the basics, adjustable ramping, separate adjustments for up and down. Adjustable dithering. Nothing fancy, but should work. It takes its input from a simple potentiometer, so this will give us huge flexibility in what we choose to use for a "throttle" device.

My question is about steering. We want to use a steering cylinder and a valve of some sort. Maybe 2 proportional valves, one for each direction, or some sort of bi-directional valve. Tonight I was looking through this device. Seems more complicated than it needs to be but it seems like the right idea

http://www.sauer-danfoss.com/stellen...e/520l0521.pdf

Do you have any experience with anything like this? I was hoping there would be some sort of basic analog device that would allow us to control the steering in a similar way as the pump control? I know I can use an orbital valve, but I don't want a traditional steering wheel. I know we can get a potentiometer joystick for under $100, so we may still play around with that idea if we can use a potentiometer for steering. Another thought if the joystick is to wierd to drive is a yolk from an airplane. I took about 30 hours of private pilot lessons and the feel of the airplane controls is pretty cool. The thought would be that just a 90 degree turn to the left of the yolk would be a full wheel turn to the left, etc... Throttle could then be a thumb lever or a twist grip or a pedal on the floor with a pot box like what is used on a golf cart.

Anyway, the basic question is how can we steer with a potentiometer. And I mean fairly innexpensively, I realize there are some pretty amazing technologies that can be used, but we just don't want to spend a fortune here. We can always upgrade down the road.

The other thought is about reverse. When the pump reverses the flow to make the vehicle back up, seems the steering will be backwards, so I am guessing we would have to somehow reverse the steering direction when in reverse. Oh, for reverse, the card will have a couple relays that will reverse the polarity going into the valve. So putting the vehicle into reverse will require flipping a switch. I am thinking this switch could signal the steering to reverse as well maybe.