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by crubier
1719 days ago
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My understanding is that Overshoot and Ringing are mostly amplitude-related phenomena, they happen even if the transfer function has a phase of zero over the spectrum, as long as the gain is greater than one over the right part of the spectrum. On the other hand, pilot induced oscillation, and the bullwhip effect seem to need some amount of phase-shift or delay to happen. |
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> Category 1 PIO: Characterized by oscillations with an underlying linear cause such as excessive time delay, phase loss, etc., which makes it easy to understand and study. Several criteria for manned aircraft focusing on excessive phase loss and time delay have already been developed. Certain criteria are based on open-loop analysis such as the Bandwidth/Pitch rate overshoot criteria [6,7], while criteria such as Neal-Smith [8] is a closed-loop analysis method with an assumed pilot model.
This one I think is kind like the non-minimum phase system I described and also like your description of delay being the root cause.
> Category 2 PIO: Characterized by nonlinear events which can be modeled as Quasi-linear events such as actuator rate limiting or amplitude limiting, etc. This is the most common type of PIO observed. Most PIOs associated with non-linear events were found to be “cliff-like” [5]; that is, the pilot reported the onset of the PIO as sudden and unexpected. Since control surface actuator rate limiting is a common non-linearity associated with modern flight control systems [9,10,11], most of the studies are focused on studying its influence on aircraft handling quality and PIO. Currently, Open Loop Onset Point (OLOP) developed by Holger Duda at Deutsches Zentrum für Luft-und Raumfahrt e.V. (DLR) is the only commonly accepted criterion for Category 2 PIO resulting from rate limited actuator in the fully rate saturated case [6,7].
This one goes way over my head
> Category 3 PIO: This category of PIO is caused by highly nonlinear events which involve transition in the control element of the aircraft or the human pilot behavioral dynamics. The non-linearities associated are more complex and cannot be modeled as quasi-linear effects. The PIOs associated with this category are also “cliff-like” [5]. Category 3 PIOs are difficult to recognize and are relatively rare, but could be highly dangerous when they do occur.
And this one is even worse