Block 1 - lecture 1 Flashcards
What’s control?
altering the performance of a system
What are the possible aims of control?
- regulate output
- tracking a varying value
- time/event driven sequencing
Benefits of process control?
- predictable
- stable
- constant
Purpose of sensor?
to measure output
Purpose of actuator?
to adjust input
Purpose of controller?
coordinates sensors and actuators
Setpoint?
a value to be maintained
Discrete-state control systems?
sequence of on/off events
Open loop control?
input isn’t controlled by the output (input on = output on)
Closed-loop control?
input is influenced by the output (eg. thermostat)
Question to ask before choosing closed-loop control?
- really needed?
- input measureable?
- save energy?
- easy to set up/maintain?
- safe?
What are the objectives of control systems?
- stable
- steady state regulation
- transient regulation
What desired quality of a control system can reduce stability?
faster responses
Steady state error?
difference between output and input at steady state
Transient response?
how the system reacts to change
What’s tuning?
adjusting a process-control loop
2 ways to measure transient response?
- response to change of setpoint
- response to transient disturbance
types of response?
- damped
- cyclic
features of a cyclic response?
- overshoot (step input change/first overshoot)
- decay rate (second overshoot/first)
- rise time (time for step change)
- settling time
Cyclic response with quarter amplitude?
decay rate of 1/4
Aims of cyclic tuning?
- reduce area either side of setpoint after rise time
- reduce decay rate
- time rise
Analog vs digital processing?
- analog is smooth
- digital has steps
ADC?
Analog to digital convertor
DAC?
Digital to analog convertor
