12-07-2014, 01:04 PM
Dynamic Characteristics
Dynamic Characteristics.pdf (Size: 398.59 KB / Downloads: 154)
Dynamic Characteristics
Dynamic characteristics tell us about how well a sensor
responds to changes in its input. For dynamic signals, the sensor or
the measurement system must be able to respond fast enough to keep
up with the input signals.
In many situations, we must use y(t) to infer x(t), therefore a
qualitative understanding of the operation that the sensor or
measurement system performs is imperative to understanding the
input signal correctly.
Dynamic Characteristics
Speed of response: indicates how fast the sensor (measurement system) reacts
to changes in the input variable. (Step input)
Rise time: the length of time it takes the output to reach 90% of full response when
a step is applied to the input
Time constant: (1st order system) the time for the output to change by 63.2% of its
maximum possible change.
Settling time: the time it takes from the application of the input step until the output
has settled within a specific band of the final value.
Transfer Function: a simple, concise and complete way of describing the sensor
or system performance
H(s) = Y(s)/X(s)
where Y(s) and X(s) are the Laplace Transforms of the input and output respectively.
Sometimes, the transfer function is displayed graphically as magnitude and phase
plots VS frequency (Bode plot).