Sensors and data acquisition Flashcards
a device that measures a physical quantity and turns it in to a signal which can be read by an instrument/observer
a sensor
the tension of a strain gauge results in?
area narrows, resistance increases
strain gauge converts ?
force along one axis to volts
force platform converts?
force along 3 axis to volts
accelerometer converts?
acceleration to volts
potentiometer converts?
angular displacement to volts
motion capture converts?
light to volts
all sensors are designed to convert a physical value into a?
electrical signal
the compression of a strain gauge results in?
area widens, resistance decreases
the physical quantity or effect that can be varied in such a way as to convey info
signal
what type of signal is continuous? what type is discontinuous?
- analog, digital
a process of converting a continuous signal into a digital signal
sampling
the sample frequency is the # of samples taken in?
1 second
the validation of specific measurement techniques and equipment
calibration
the equation used if the calibration is linear
y=mx+b
with what 2 values can we determine the force for any voltage output
slope and offset
the influence of the previous history of the system on its subsequent response to a given stimulus
hysteresis
the gradual change in a transducers voltage output with out an accompanying change in applied force
drift
could be due to the system warmign up
drift
steps of data aquisition
- sensor
- breakoutbox
- multiplexor
- amplifier
- sample and hold circuit
- analog to digital converter
- storage device
- software
2 problems with the multiplexor
- effective sampling rate is decreased (the more sensors that are added)
- delay between taking each sample
what is the sample skew created by?
the delay between taking each sample (the multiplexor)
the # of times a signal is amplified is called a?
gain
the A/D is limited by 3 things
- the range of voltages it can read
- the # of magnitude options
- the # of times options
the magnitude resolution of an A/D is usually expressed in units of?
BITS
a 4 bit has how many levels of info? a 2 bit has how many levels of info?
- 2^4 =16
- 2^2 = 4
the common # of steps is ? if the voltage range is 0-10 V, what is the amp between each step?
- 4096
- 10/4096= 0.00244V
the # of steps that divides an A/D range is called its
resolution
