Talk:Ball-and-disk integrator

This is a very poorly written article in that it has too many grammatical errors. It's important to keep our standards high; articles with grammatical errors suffer from a lack of credibility. I know absolutely nothing about the subject or I'd volunteer to clean it up myself. Wdwrx (talk) 13:45, 1 January 2013 (UTC)

Alrighty... I cleaned it up a bit.... just changed a few words to make it read better, and deleted one sentence fragment that appeared to be somewhat redundant anyways. Sorry, I hate to be a grammar nazi but sometimes I just can't help myself Wdwrx (talk) 13:55, 1 January 2013 (UTC)

Merger proposal
This device is the core of a Differential analyser, and this one source-article will be better integrated in the more general article.--Demostene119 (talk) 11:04, 14 February 2014 (UTC)


 * Oppose The component and the system are distinct enough to justify separate articles. Also there are plenty systems using ball-and-disc mechanisms, but that aren't differential analysers. Andy Dingley (talk) 22:14, 25 February 2014 (UTC)
 * Oppose The differential analyzers used wheel-on-disk integrators, not the ball.  From what I've read, the ball was useful when it could be loaded heavily, providing more output torque than a wheel. --Wtshymanski (talk) 21:21, 27 February 2014 (UTC)

Contradictory figure caption
The text describes the inputs as a spinning disk and carriage with the output appearing on a shaft. The figure caption describes a "cylindrical input shaft, ball and output disk". Which is it? 130.246.58.72 (talk) 09:21, 22 October 2018 (UTC)
 * Discs are always input. Otherwise you can't get a zero term (by moving the ball to the centre).
 * Potentially, the mechanism works both ways (and I'm sure that someone, somewhere, has done it each way). But the ratios between the two, dependent on the ball position, are then the reciprocals of each other.  It's necessary to be able to produce a zero term (and so the disc needs to be the input). If you drove the shaft as the input, then the mechanism would become unworkable for the smaller radii. Andy Dingley (talk) 10:47, 22 October 2018 (UTC)
 * Question - should the disk be described as the input? To me the disk is simply a constant timebase, the input is the ball position. Martin of Sheffield (talk) 16:38, 22 October 2018 (UTC)
 * Yes. The article scope, and the machine described here, is one small component of what is usually a larger machine. It has "input" and "output", as entirely neutral terms. There's no sense of one being a time (or other) dimension, until the integrator is made into something broader and with a more specific purpose. Andy Dingley (talk) 10:49, 23 October 2018 (UTC)
 * OK, I see what you mean, just haven't seen it used as other than a timebase. Thanks, Martin of Sheffield (talk) 11:09, 23 October 2018 (UTC)

Missile speed vs position
"The accelerometer for forward movement transmitted its position to the ball position radial arm, causing the ball fixture to move away from the disk center as acceleration increased. The disk itself represents time and rotates at a constant rate. As the ball fixture moves further out from the center of the disk, the ball spins faster. The ball speed represents the missile speed, the number of ball rotations represent distance traveled."

This seems inaccurate. If the disc rotates at a constant rate, then the ball speed is directly proportional to acceleration, and the speed will be zero if there is zero acceleration. That's clearly not true for missile speed. And the output can't be distance travelled, because integrating acceleration gives you speed; you need to integrate that again to get distance. Since the distance travelled seems important, did the missile use two integrators in series to find the distance? Or was the output from the accelerometer already integrated, like the output of a PIGA accelerometer? User:CamTarn (talk) 07:24, 2 February 2020 (UTC)
 * Good question! Needs looking into.  would be someone who'd know this, although they haven't edited for some time. Also the Pershing ST-120 introduction manual is on Scribd.  I think it may well be (given the history here) as you describe, in relation to PIGA. Andy Dingley (talk) 12:54, 2 February 2020 (UTC)