Timeline for For continuous systems that in Quasi-static / Static Equilibrium are Memoryless?
Current License: CC BY-SA 4.0
5 events
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| Jun 6, 2022 at 16:00 | comment | added | L92MD14 | @aconcernedcitizen yes so to get a second order system that is mass•d2x/dt2 + damping•dx/dt + stiffness•x + mass•gravity = external forcing function can be brought into state space after noting that mass•gravity is balanced out by a stiffness•common_static_deflection term. Then if the input, which is the external forcing function (u and du/dt), is ever so slowly applied, then we can assume d2x/dt2 and dx/dt are zero. Yet the outputs and the state position are NOT zero: dy/dt nor y nor x. So I can’t see that as still a zeroth order system. There are rate terms dy/dt & also y & x. | |
| Jun 6, 2022 at 6:59 | comment | added | a concerned citizen | @L92MD14 If a zeroth order system is defined as static that's because it has absolutely zero dynamics involved. Its output will always be K times input, with K being some constant. It's a glorified wire. | |
| Jun 5, 2022 at 23:09 | comment | added | L92MD14 | Ok I actually see what you are saying - sorry I hadn’t realized that when I wrote my previous comment. So it is a true static analysis which where the confusion comes up, between a true static analysis which is in a sense memoryless. Though do you think I should post a follow on question about Quasi-statics represented in State Space as I showed above? If you look up there we see that the system is a sort of static (quasi-static) because dx/dt is zero but not x and also the outputs are not zero, and so are driven by the time varying inputs u & du/dt. This is Quasi-static due to slow loading | |
| Jun 5, 2022 at 22:53 | comment | added | L92MD14 | Thanks for the response, but I am sorry to disagree with you that I am confusing static and memoryless. I am not confusing them (though I admit that maybe I don’t understand their context - I will screenshot the section soon), as according to PHILLIPS4e Digital Control System Analysis & Design Chapter 10, it defines a system that is Static to be one whose states are memoryless. | |
| Jun 5, 2022 at 22:30 | history | answered | TimWescott | CC BY-SA 4.0 |