Sensors Flashcards
Sensors Define
A device that detects and responds to some type of input from the physical environment
Responds to a physical stimulus and transmits a resulting impulse
Sensor vs Transducer
Sensor: produces a signal relating to the quantity being measures
Transducer: converts energy from one form to another
Absolute/ Incremental
Absolute: Detect a unique position
Incremental: Measure a relative position which depends on a prior position
Analogue vs Digital
Analogue: Continuous output
Digital: Discrete digital output
Analogue Sensor Measurement
Output a signal that correlates to the quantity it is measuring
can be linear, polynomial or exponential
Signal Conditioning
OPAMPS provide amplification when connected to either an inverting or non-inverting
Filtering: Low Pass, High Pass, Band Pass
Range
Limits Between which the input can vary, two values
Span
Maximum value - Minimum value for the inputs
Error
Error = Measured value - true value
Accuracy
The extent to which the value indicated by a measurement system might be wrong. Percentage of the full range of the output.
Sensitivity
How much the output there is per unit input
Hysteresis Error
Maximum difference in output for increasing and decreasing values
Non-linearity error
Occurs as a result of the assumption of linearity
Repeatability
Repeatability = (max-min)/range *100
Ability to give the same output for repeated tests
Stability + Drift
Stability: Ability to give the same output when used to measure a constant input over a period of time
Drift: Change in output that occurs over time
Zero drift: change in output, no change in input
