dmplot
(Not recommended) Interpret disk gain and phase margins
dmplot
is not recommended. Use
diskmarginplot
instead.
Syntax
dmplot dmplot(diskgm)
[dgm,dpm] = dmplot
Description
dmplot
brings up a plot that
illustrates the disk gain margin (dgm
) and disk phase
margin (dpm
) for a sample system. Both margins are
derived from the largest disk that
Contains the critical point (–1,0)
Does not intersect the Nyquist plot of the open-loop response L
diskgm
is the radius of this disk and a lower bound on the
classical gain margin.
dmplot(diskgm)
plots the maximum
allowable phase variation as a function of the actual gain variation for a
given disk gain margin diskgm
(the maximum gain variation
being diskgm
). The closed-loop system is guaranteed to
remain stable for all combined gain/phase variations inside the plotted
ellipse.
[dgm,dpm] = dmplot
returns the data
used to plot the gain/phase variation ellipse.
Examples
References
Barrett, M.F., Conservatism with robustness tests for linear feedback control systems, Ph.D. Thesis. Control Science and Dynamical Systems, University of Minnesota, 1980.
Blight, J.D., R.L. Dailey, and Gangsass, D., “Practical control law design for aircraft using multivariable techniques,” International Journal of Control, Vol. 59, No. 1, 1994, 93-137.
Bates, D., and I. Postlethwaite, Robust Multivariable Control of Aerospace Systems, Delft University Press, Delft, The Netherlands, ISBN: 90-407-2317-6, 2002.