Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!rutgers!tut.cis.ohio-state.edu!cwjcc!hal!ncoast!mattern
From: mattern@ncoast.ORG (Duane L. Mattern)
Newsgroups: sci.electronics
Subject: Re: Mechanical actuators
Message-ID: <13775@ncoast.ORG>
Date: 25 Jun 89 20:47:33 GMT
References: <1436@xn.LL.MIT.EDU>
Organization: Cleveland Public Access UN*X, Cleveland, OH
Lines: 35

rsteele@LL-XN.ARPA.UUCP (Rob Steele) writes:
>I need a mechanical actuator to operate under microprocessor 
>control.  Ideally it would be a solenoid that works off of
>5 VDC and not much current.  The thing will be pulsed at 
>around 7 Hz. with a

Some questions...                      0 1 0 1 0 1 0
- Pulsed?  Like in a 50/50 square wave _|-|_|-|_|-|_ ?
- Do you need or will you want in the future, a finite resolution
  in the movement or just bang-bang?
- Have you consider using a stepper motor and a rod-crank mechanism
  to generate straight line movement, or do you need specific
  velocity, acceleration characteristics of the movement?
- How accurate do you need the pulse frequency, 7.000 Hz, or
  +/- 1 Hz.  If you don't need high accuracy, you could use a
  toy DC motor to drive you rod-crank mechanism.  Even the rod
  and crank could be obtained from a toy.

You could build a solenoid yourself.  It would just take some 
windings.  We did that at Purdue for one of those ME land 
vehicle races.  We used a two speed gear box which shifted 
gears automatically on a slope which was detected by a mecury switch.
The solenoid shifted the transmission by force meshing a new gear.
The solenoid force will be proportional to the current which depends
on the voltage supply and the number of windings squared (I think).
You can find this in any physics book (mines not handy). 
Our solenoid was driven by batteries with a hand wound solenoid.
Frequency response will of course be determined by the magnitude
of the maximum possible force generated and the size of the load,
which also includes the mandrel.
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|  Duane Mattern (216)433-8186         (mattern@ncoast.uucp)        |
|  Sverdrup Technology, Inc.           at NASA Lewis Research Center|
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