Re: equations for inertial simulator

On Feb 23, 3:15 pm, j...@xxxxxxxxxxxxxxxxxxxx wrote:
How about a much smaller pendulum going through a series of pulleys
such that the mechanical advantage is for the pendulum, thus making,
say a 10 pound bob, feel like the 1 ton bell?

The length would of course have to be diddled to get the same period
as the bell.
Jim Pennino

The trouble with any sort of mechanical advantage system is that if
you arrange it to make the rope feel harder to pull, it also reduces
the distance the rope moves through. Since the design goal is to make
the person pulling on the rope feel like he's manipulating the heavy
bell, both the force and the distance of rope movement need to be
correct.

So it looks like the torque produced by the motor can't depend simply
on its position, since it also depends on the external torque imposed
by the person pulling on the rope. To use the same example I had
before, suppose the rope is held still at such a position as to hold
the shaft 90 degrees up from equilibrium. Then the motor must provide
a large torque to simulate the weight of the heavy bell. However, if
the rope is then suddenly released, the motor must provide a much
smaller torque in the same position, only enough to accelerate the
motor itself in the same way as the large bell would if let go from
that position.

Maybe this means you need a strain sensor on the rope (or
equivalently, a torque sensor on the rope wheel before it is attached
to the motor shaft). However, I can't help feeling it should be
possible to obtain equivalent information from the position and speed
of the shaft itself. That is, since the torque being applied by the
motor at any time is known, and the position of the shaft (hence its
velocity and acceleration, by differentiation) is known, the torque
imposed by the rope must be uniquely determinable.


.

Relevant Pages

  • Re: equations for inertial simulator
    ... pendulum, ignoring the torque applied by the rope altogether. ... Then the rope just does whatever it does. ... Now suppose the rotational inertia of the simulator's motor ...
    (sci.physics)
  • Re: equations for inertial simulator
    ... ignoring the torque applied by the rope altogether. ... Then the rope just does whatever it does. ... i.e. the required motor torque is proportional to the sin of the shaft ... the motor simulate the swinging of the original bell if unperturbed. ...
    (sci.physics)
  • Re: equations for inertial simulator
    ... as the bell. ... the distance the rope moves through. ... Then the motor must provide ... a large torque to simulate the weight of the heavy bell. ...
    (sci.physics)
  • Re: equations for inertial simulator
    ... interest in human-powered bell ringing, ... I think you'd have to control the speed as well as the torque. ... Yes, if the rope is released, the motor should simulate the swinging ...
    (sci.physics)
  • Re: equations for inertial simulator
    ... | rigidly attached to the shaft. ... With no external torque applied to the shaft, ... | input torque is applied to the motor shaft. ... | to a wheel mounted on the bell. ...
    (sci.physics)
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