Randall,

What amount of dither do you think would be adequate?  I suppose it 
could best be expressed as variation in the spring strain, or in 
whatever other way you suggest.

Thanks,
Brett

At 06:47 PM 8/15/2011, you wrote



>   I see this process as a potential energy function that is very 
> much like the vertical seismometer, except turned upside 
> down.  Extending the spring and then releasing, it does not return 
> to a perfectly defined equilibrium point; i.e., it finds a new very 
> slightly different places to come to rest because of the 'ratchety' 
> nature of the restoring force at the very low levels.  Much of my 
> experimental work is consistent with this 'heretical' viewpoint, 
> and I think it is the very reason, Brett, you would do well to try 
> and do some low level dithering of your instrument.  Allan 
> Coleman's approach seems to accomplish this by means of his passive 
> leveling arrangement.


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