Jinx wrote:

>>Does this need to be a random-access unit, or are you just
>>testing durability of the keypad?
>>    
>>
>
>Bob, the 'fingers' have to simulate a person using the device
>
>A PIC will take serial data from a PC and activate the keys
>
>After a chat with the other principals last night, they suggested I keep
>it simple. Which, given my work load, I'm inclined to go along with
>
>What we're doing will be demonstrated to interested parties and
>should be kept as compact as possible. So that ruled out air and
>XYZ actuators and all the other great contributions
>
>I've also been told that there are some (slightly important) timing
>specs involved and that pretty much means solenoids
>
>  
>
The solenoid method sound good but would be hard IMHO to control the 
pressure applied to the key.

What I would suggest is to make fingers of steel that a would be the 
weight of the pressure you need to apply. Then wind an electro magnet 
that would lift the steel finger off the key.  It would be a bit of a 
power hog  being all electromagnets would be energized when no keys were 
pushed .  But it would have the advantage of being able to change the 
key pressure by just adding or removing weight to the finger.  The 
finger would really only need to move just enough to activate the key. 
Say 1/8" to 1/4" maybe.

Also for this to work the key pad would have to be positioned  so the 
finger would be verticle.

Just out of curiosity what size is the keybord and number of keys?  IE  
4 X 5 , 1/2" SQ keys.

RECON
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