- #1
LM741
- 130
- 0
hi alll!
just a quick one.
You know when you design a controller - you go and plot the open loop transmission, L(jw) on a nichols plot, where L(jw) = C(jw)H(jw) P(jw)
where P and C are the plant and controller respectively. You then 'manipulate' this plot (i.e. vary your controller) until your design specs are met. My question is once you have a gain margin - what does this actually tell us - say we have gain margin of -5dB.
does this tell us that our controller gain can only increase by 5dB before the system bcomes unstable (assuming the system was already stable).
The thing i don't get is that our controller gain is fixed and doesn't change after we design it! so which gain (the controller or plant or H(hw) ) does the gain margin put a limit on?
think i might be missing something...
thanks!
just a quick one.
You know when you design a controller - you go and plot the open loop transmission, L(jw) on a nichols plot, where L(jw) = C(jw)H(jw) P(jw)
where P and C are the plant and controller respectively. You then 'manipulate' this plot (i.e. vary your controller) until your design specs are met. My question is once you have a gain margin - what does this actually tell us - say we have gain margin of -5dB.
does this tell us that our controller gain can only increase by 5dB before the system bcomes unstable (assuming the system was already stable).
The thing i don't get is that our controller gain is fixed and doesn't change after we design it! so which gain (the controller or plant or H(hw) ) does the gain margin put a limit on?
think i might be missing something...
thanks!