Mass-Spring-Damper Simulation

CSGnet Archive CSG2015
21

The concept is to introduce the term action in units other than force.

···

On Sun, Aug 7, 2016 at 8:24 PM, Martin Taylor mmt-csg@mmtaylor.net wrote:

[Martin Taylor 2016.08.07.23.21]

  On 2016/08/7 8:40 PM, PHILIP JERAIR

YERANOSIAN wrote:

    Here's a conversation we had where we used a

simulator to model a disturbance to a mass on a spring and we
were discussing what the controlled variable was - I don’t think
we reached a conclusion, but the conversation pivoted between
Rick and Bruce. What I propose is to run a simulation of the
experiment where the mass on the spring is subject to circular
motion and it is the centripetal motion of the mass (i.e. a
moment of inertia) which causes the linear displacement of the
spring.

Given the equivalence between acceleration and gravity, which I

believe has been tested out to quite a few decimal places, what
would be the point? How would it differ from having a heavier weight
on the pendulum? Or were you thinking of introducing angular
accelerations into the mix? If so, what would they tell you?

Martin

      On Mon, May 18, 2015 at 11:20 AM,

PHILIP JERAIR YERANOSIAN pyeranos@ucla.edu wrote:

[Philip 5.18.15]

          Instead of running the TCV on the position of a mass on a

spring, why don’t we run this TCV analysis on a
gyroscope’s orientation? This would make for a much
richer discussion, because the physical laws are more
complex. Perhaps we could even devise a controller
similar to the one Bill described for controlling the
position of a mass. Angular orientation would substitute
for mass position, angular velocity for mass velocity, and
torque for applied force.

                On Sun, Feb 8, 2015 at 7:07

AM, Martin Taylor csgnet@lists.illinois.edu
wrote:

                    [Martin

Taylor 2015.02.07.17.35]

                        [From Rick Marken

(2015.02.07.1400)]

** negative feedback
exists when the output of a system has a
negative effect on the cause of that
output.**

                    Why do you keep reiterating what has been agreed

by all from the get-go, as if it were a critical
argument against the fact that equilibrium
systems are (as they indeed are and have been
shown to be) negative feedback systems?

                    EQUILIBRIUM SYSTEMS DO NOT CONTROL!!!!!  We get

it, have got it, never have had a problem with
it. It’s just a fact.

                    So please stop using it as though it were an

argument.

                     That's a funny definition. "The cause"

of the output of a control system is the
combination of the output function and the
history of the error variable (two causes). Is
that not so?

                    My preferred definition deals with changes in

variables, not their causes, nor their values,
and says nothing about what variable you are
considering, something like this: * Negative
feedback exists when a change in a variable
result in an influence that opposes the
change.*

                    The actual words might be better put, but that's

my idea of negative feedback.

                    In the case of the spring, changing the value of

the variable “position of the mass” changes the
compression or extension of the spring, which
results in an influence that opposes the change
of position. (See attached figure – it doesn’t
seem to want to go in-line).

                    Martin

                            :So the mass

spring system is a negative feedback
system that doesn’t seem to resist
disturbances; that is, it doesn’t
control.