Took the plunge, bought a 3500 series

In my quest for electro-hydraulic power steering for my electric vehicle project, I went ahead and purchased a controller for the pump, a 12v 60A max power steering pump from a Toyota MR2.

I know the controller will basically do what I need it to do (control the motor better than just hard-wiring it to the battery), but what I have yet to learn and be convinced of is that it will do what I WANT it to do that is, help my EV be efficient by drawing less current when it is not needed).

There are numerous ways to tackle this. The one I'm hoping for is by speed control- that is, the faster my vehicle is going, the less power assist the steering has. This is ideal, as I can set zero assist for a vehicle speed I'll never attain, but will get max assist when I need it the most (like moving around in a parking lot).

If this works well, I'll be purchasing an even larger controller for my next project, which I'll want to independently control two motors- the power steering, and the A/C.

I'll post up results, and maybe give some folks reading this a little food for thought in the robotics arena, and beyond!

update:<BR><BR> Got the 3500. It's a little smaller than I initially thought it would be. That's a good thing! I'll be putting this in a small plastic box with another small circuit and a cooling fan or two. The controller won't see high amps constantly, but rather low amps most of the time (running the pump for minimal power assist) and surges of power during low-speed turning.
The additional circuit is to change a +5vdc square wave into a voltage value from 0 - 2.5v, so that I can read the speedometer (the square wave) and operate the speed of the electric power steering pump as an inverse function of vehicle speed. To do this, the controller will think the motor is going from backward to stop, rather than from stop to forward (thanks, Cosma, for making that make sense!).<BR><BR>The power steering pump and reservoir are mounted. For good cooling, the controller box will not be mounted under the hood, but rather in an area under the pickup bed.<BR><BR><BR><IMG style="WIDTH: 297px; HEIGHT: 209px" height=200 alt="" hspace=0 src="www.deyemeracing.com/an/images/AN1_071007-3.jpg" width=283 align=baseline border=0>
The power steering fluid reservoir (the OEM mechanical pump included an integrated reservoir).

www.deyemeracing.com/an/images/AN1_071009-3.jpg" width=475 align=baseline border=0>
...and the pump itself, mounted on the fenderwell, near the firewall.

I have a plastic box to put the controller and "interpreter" circuit in, and the interpreter circuit has been built and tested. Now it's time to do some soldering, and turn the interpreter circuit into a real circuit (it's now on one of those plastic Radio Shack circuit mockup boards), and get the two put together.



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