Lecture 1 - Measurement Flashcards
What are the 3 main purposes of a measurement system?
1) Obtain data about an event
2) Inspection or testing
3) as an element in a control system
3 basic constituent elements?
Sensing element, Signal Conditioner & Display
What does the sensing element/transducer do?
takes in information about the system.
Changes it into a suitable form to be given a value.
What does the Signal conditioner do?
converts signal from transducer into a condition for display.
What does the Display do?
Shows the output of the system e.g. a pointer on a scale
Name some common parameters
displacement, speed, fluid flow, acceleration, force etc
What factors can influence your choice of sensor?
Parameters nature, cost, reliability & quality of information
What are 2 distinct areas where sensors are used?
Gathering info and Controlling systems
Example showing the difference between a sensor and transducer?
A light bulb used to light a room is a transducer but used to test a circuit is a sensor
what’s the basis of open loop control
to control a signal at a preset value.
What is an issue with open loop control?
Any factors that change or disturbances that occur will render the output corrupt
How does closed loop control work?
the desired value (set point) is compared to the feedback signal the difference is known as the error. This is then altered to better the system performance and becomes a control signal.
Whats the advantage of a closed loop system?
Compensate for a disturbance
Describe a zero order system?
graph: Up then right angle and flat right
Describe a first order system?
Curve to the right the flat right
