Control Systems and Dynamics Flashcards
7 cards from real ME or MEng Master of Engineering 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 and Dynamics flashcards as text
How is the transfer function of a linear time-invariant system formally defined?
Answer: The ratio of the Laplace transform of output to input with zero initial conditions
The transfer function is the Laplace transform of the output divided by the Laplace transform of the input, assuming all initial conditions are zero.
In a closed-loop control system, what is the primary purpose of feedback?
Answer: To compare the output with the desired input and reduce error
Feedback compares the actual output with the reference input to generate an error signal, which the controller uses to drive the error toward zero.
A PID controller combines which three control actions?
Answer: Proportional, Integral, and Derivative
PID stands for Proportional, Integral, and Derivative — actions that reduce error magnitude, eliminate steady-state offset, and improve transient response, respectively.
What is the steady-state error to a step input for a Type 1 control system?
Answer: Zero
A Type 1 system contains one open-loop integrator, which drives the steady-state error to zero for a step (position) input.
In the s-domain, what is the transfer function of an ideal differentiator?
Answer: s
Differentiation in the time domain corresponds to multiplication by s in the Laplace domain, so the transfer function of a differentiator is simply s.
What information does a Bode plot provide about a control system?
Answer: Magnitude and phase of the frequency response versus frequency
A Bode plot consists of two graphs: the magnitude (in dB) and the phase (in degrees) of the open-loop frequency response plotted against logarithmic frequency.
The characteristic equation of a control system is obtained by setting which expression to zero?
Answer: The denominator of the closed-loop transfer function
The characteristic equation is found by setting the denominator of the closed-loop transfer function to zero; its roots (poles) determine stability and transient behavior.