In Kinematics class we were learning about cam design, and about how you want to minimize the 'jerk' and 'ping' of the follower on the cam. I understand jerk. That is what I feel when I'm in a car which suddenly accelerates. I feel jerked back.
I don't know what ping is, other than the derivative of the jerk. How would I feel ping?
Also, does the derivative of ping have a name?
Dear Stacy Haponik:
The derivative of jerk has no standard name. Specifications have been written to limit jerk for passenger vehicles. No limits exist for higher derivatives.
David A. Smith
"N:dlzc D:aol T:com \(dlzc\)" wrote in news:NAaIf.32656$jR.23113@fed1read01:
I'll go a little further than David.
When you model a mechanical system you pretty much lose interest at acceleration, for passive systems.However, if you try and model feed- forward, or feedback systems, you usually include both integrals and differentials of the signal of interest.
The human proprioception demands such a feed forward device - you want to hold your head in the same place, so you want to exert a force so your feed forward system cares about jerk.
If a second order feedforward controller was justified, you'd worry about d jerk/dt, but in practice that does not seem necessary.
Cheers
Greg Locock
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