Control Systems Flashcards
7 cards from real BME practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Control Systems flashcards as text
In a PID controller, which term is responsible for eliminating steady-state error?
Answer: Integral (I) term
The integral term continuously accumulates error over time and generates an output that drives steady-state error to zero by adding an effective open-loop integrator.
In state-space representation ẋ = Ax + Bu, y = Cx + Du, the matrix A is called the:
Answer: System (state) matrix
Matrix A is the system (state) matrix; its eigenvalues are the natural frequencies of the system, and it governs how state variables evolve without external input.
What is the primary practical drawback of applying pure derivative (D-only) control action?
Answer: It amplifies high-frequency measurement noise
Differentiation magnifies rapid signal changes, so a pure derivative controller greatly amplifies high-frequency noise present in measured outputs, making stand-alone D control impractical.
The Nyquist stability criterion determines closed-loop stability based on:
Answer: Net encirclements of the −1 + j0 point by the Nyquist plot
Using Cauchy's argument principle, the Nyquist criterion counts net clockwise encirclements of −1 + j0 by the open-loop Nyquist plot to determine the number of unstable closed-loop poles.
A system is completely controllable if:
Answer: Any initial state can be driven to any desired state in finite time via an appropriate input
Complete controllability requires that for any initial state x₀ and desired final state xf, there exists an input u(t) that transfers the system from x₀ to xf in finite time; this is verified by the rank of the controllability matrix.
Dominant poles of a higher-order system are those located:
Answer: Closest to the imaginary axis in the left half-plane
Dominant poles are closest to the imaginary axis (smallest magnitude of negative real part), so they decay most slowly and exert the greatest influence on the transient response.
For a type-1 feedback control system subjected to a unit ramp input r(t) = t, the steady-state error is:
Answer: 1/Kv, where Kv is the velocity error constant
A type-1 system has one open-loop integrator, giving a finite velocity error constant Kv; the steady-state ramp error equals 1/Kv, which is nonzero but finite.