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  2. Nyquist stability criterion - Wikipedia

    en.wikipedia.org/wiki/Nyquist_stability_criterion

    The Nyquist plot for () = + + with s = jω.. In control theory and stability theory, the Nyquist stability criterion or Strecker–Nyquist stability criterion, independently discovered by the German electrical engineer Felix Strecker [] at Siemens in 1930 [1] [2] [3] and the Swedish-American electrical engineer Harry Nyquist at Bell Telephone Laboratories in 1932, [4] is a graphical technique ...

  3. Stability criterion - Wikipedia

    en.wikipedia.org/wiki/Stability_criterion

    Stability criterion. In control theory, and especially stability theory, a stability criterion establishes when a system is stable. A number of stability criteria are in common use: Stability may also be determined by means of root locus analysis. Although the concept of stability is general, there are several narrower definitions through which ...

  4. Harry Nyquist - Wikipedia

    en.wikipedia.org/wiki/Harry_Nyquist

    The Nyquist stability criterion can now be found in many textbooks on feedback control theory. His early theoretical work on determining the bandwidth requirements for transmitting information laid the foundations for later advances by Claude Shannon , which led to the development of information theory .

  5. Classical control theory - Wikipedia

    en.wikipedia.org/wiki/Classical_control_theory

    Tools include the root locus, the Nyquist stability criterion, the Bode plot, the gain margin and phase margin. More advanced tools include Bode integrals to assess performance limitations and trade-offs, and describing functions to analyze nonlinearities in the frequency domain.

  6. Hall circles - Wikipedia

    en.wikipedia.org/wiki/Hall_circles

    The M circle with M = 0.45 is highlighted in red and intercepts the Nyquist plot at frequencies . Hall circles (also known as M-circles and N-circles) are a graphical tool in control theory used to obtain values of a closed-loop transfer function from the Nyquist plot (or the Nichols plot) of the associated open-loop transfer function.

  7. Nonlinear control - Wikipedia

    en.wikipedia.org/wiki/Nonlinear_control

    These systems can be solved by powerful frequency domain mathematical techniques of great generality, such as the Laplace transform, Fourier transform, Z transform, Bode plot, root locus, and Nyquist stability criterion. Nonlinear control theory covers a wider class of systems that do not obey the superposition principle.

  8. Control theory - Wikipedia

    en.wikipedia.org/wiki/Control_theory

    Alexander Lyapunov in the 1890s marks the beginning of stability theory. Harold S. Black invented the concept of negative feedback amplifiers in 1927. He managed to develop stable negative feedback amplifiers in the 1930s. Harry Nyquist developed the Nyquist stability criterion for feedback systems in the 1930s.

  9. Single-input single-output system - Wikipedia

    en.wikipedia.org/wiki/Single-input_single-output...

    Bode plot, Nyquist stability criterion, Nichols plot, and root locus are the usual tools for SISO system analysis. Controllers can be designed through the polynomial design, root locus design methods to name just two of the more popular. Often SISO controllers will be PI, PID, or lead-lag.