Week 4 Flashcards
what is a continuous time signal?
Represented by a continuous function of time u(t), y (t), x (t)
what is a Discrete-time signal?
Represented by a sequence of numbers
u1, u2, . . ., y1, y2, . . . (with a constant separation in time, fixed period)
what is an event?
Represented by a sequence of (finite) numbers occuring at some moments in time (no fixed period)
what is a state?
one or more variables (including output signals?)
x (t), xk
what is a state transition law?
how state changes over time
what is an output function?
How the output of the system depends on the state
what is control theory?
the branch of engineering which deals with the identification or modeling of systems and the design of methods to control their outputs.
what is a plant?
The given system we want to control
what is a setpoint?
The signal we want the system’s output to be
what is a controller?
The system (sometimes just a function, i.e. no state) we design to control the plant
what is an error?
The difference between the setpoint and the output of the plant i.e. what we want the plant to do vs. what it is really doing
what is the stability of a system?
Has many different definitions. BIBO stability (Bounded Input Bounded Output) is widely used: If the input of the system stays within some bounds the output will also be bounded (i.e. nothing blows up)
what is perturbation?
A signal, we cannot control, that affects the output of the plant
what is a transient?
The period of time from setting the setpoint until the system does what we actually requested (Nothing changes instantaniuosly)
what is a steady state?
Period of time we consider the system is behaving as we wanted (after settling time).
what are examples of control systems?
-elevator
-driving
what is a block diagram?
A graphical way of representing the connections/relations between sub-systems in control theory
what 2 sides does a DC motor have?
-electrical
-mechanical
what is the electrical side of a DC motor?
When you plug a battery to the motor
what is the mechanical side of a DC motor?
The acceleration of the motor axis
what is an open loop control?
a type of continuous control system in which the output has no influence or effect on the control action of the input signal
what is a feedback control?
A feedback controller measures the output of a process and then manipulates the input as needed to drive the process variable toward the desired setpoint.
what is a cascade control?
Cascade control involves the use of two controllers with the output of the first controller providing the set point for the second controller, the feedback loop for one controller nestling inside the other
what is a proportional controller?
a control system technology based on a response in proportion to the difference between what is set as a desired process variable (or set point) and the current value of the variable.
