Larry Smith wrote in  MMD 030908,

> Technically, yes, all automata of any sort, including orchestrions,
> music boxes, band organs, and automata figures are robots.  However,
> the more modern function -- al definition of "robot", which is not
> likely to be in modern dictionaries yet and may never be -- implies
> some sort of self-regulating feedback.  That is, a robot not only
> manipulates the environment but also senses it and responds to it.

A number of respondents have suggested that feedback might be included
as part of the criteria for defining a system as robotic.  The most
basic pneumatic player piano has at least five feedback systems, I would
guess; the more sophisticated reproducers may have more.

It is my understanding that some of the newer solenoid player systems,
also have electronic feedback associated with the striker solenoids.

Feedback: The return of a portion of the output, or processed portion
of the output, of a (usually active) device to the input. The feedback
signal will have a certain magnitude and phase relationship relative to
the output signal or the input signal. This relationship can be used to
influence the behavior, such as the gain and stability, of the overall
circuit.

Common feedback systems used on pneumatic player pianos:

1.  The first thing that comes to mind with respect to feedback systems
on pneumatic players would be the roll tracking mechanism, which
monitors position of the roll and sends feedback to the centering
system.  This would fit the definition of a closed loop feedback
system.

Closed loop feedback (feedback as information) deals with correcting
errors.  Since this type of system has ways of correcting errors,
errors are of primary importance.

2.  I believe a relief valve system on a reservoir bellows could
rightly be considered a closed loop feedback system also.  Input: when
the bellows are collapsed to the point of engaging the relief valve.
Feedback: the relief valve opens, allowing the bellows to open as
necessary until the relief valve is closed.

3.  A spinning spring and weight type governor used in mechanical
musical devices is an example of a simple, elegant, self-contained,
closed loop feedback system for controlling speed.

4.  The end-of-roll/rewind signal system.

5.  The rewind shut off sensor which monitors the paper or lack thereof
on the take-up spool.

There are probably other obvious examples of these simple, yet very
effective feedback systems used in Mechanical Music machines that
I am overlooking.

Tom Lear
Tujunga, Calif.