Lecture 2 - Motion Flashcards
What are the types of motion sensors?
Linear and angular displacement, Proximity & acceleration
What is displacement?
distance measured in a stated direction from a reference point.
What is linear displacement?
if displacement is measured in a straight line
What is angular displacement?
if displacement is measured in terms of angle of rotation about an axis
Devices used to measure LD?
rulers, slip gauges, micrometers & vernier gauges.
Dial test indicator (More accurate)
What is a linear potentiometer ?
a variable resistor, made of a sliding contact moving over resistive material. Made from copper alloys
What is capacitance given by?
C = (EoErA)/d
Eo = 8.85*10^-12
Change in Capacitance?
C = (EoErA)/d+x
What does LVDT stand for?
Linear Variable Differential Transformer
What is an LVDT made up of?
1 primary, 2 secondary windings. Connected to provide a voltage differential
Describe the LVDT operation?
secondary voltage are in phase and when connected should cancel. iron core moved into one secondary winding where the flux linkage increases and the other winding’s decreases. once the core is fully in the winding the output voltage is saturated.
What is a strain gauge (SG)?
measure changes in size of an object due to strain (stretched or compressed). as this occurs the resistance also changes.
Describe the SG Operation
Stretching the filament reduces area and inscreases length.
R = (p*L)/A
What does the gain factor equal?
G = Electrical strain/Mechanical strain
= (Change in R/R)/(Change in L/L)
