Learning goals

Knowledge (remember and understand)

  • Explain how the peak in the sensitivity and complementary sensitivity functions relate to gain and phase margins.
  • Explain the concept of a bandwidth. Shall we define it using the sensitivity or the complementary sensitivity functions?
  • Give the two “waterbed effect” integral formulas. You do not have to remember the formulas exactly but at least the essence.
  • Give the SISO version of interpolation conditions of internal stability. Namely, assuming that the transfer function of the system vanishes at z in the right half plane of the complex plane, it must hold that S(z) = 1. Similarly, for an unstable pole p of the system, it must hold that T(p) = 1.
  • Give the lower bound on the peaks in the weighted sensitivity function in presence of poles and/or zeros in the right half plane.
  • How does the time delay in the system affects the achievable bandwidth?
  • How does the presence of disturbance affect the achievable bandwidth?
  • What conditions on system transfer function(s) are imposed by the saturation of actuators? More accurately, under which conditions is it guaranteed that the actuators do not saturate?
  • Explain the concept of directionality in MIMO systems.
  • Explain the condition number of the matrix of transfer functions. How can it be computed? Perhaps only approximately.
  • How does the presence of input multiplicative uncertainty affect the achievable behavior of the closed-loop transfer functions?

Skills (use the knowledge to solve a problem)

  • Analyze the provided linear model of dynamics of the system to be controlled in order to learn the limitations on achievable performance such as bandwidth, resonant peak, steady-state regulation error etc.
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