Sensor is prone to failure?
What is the cause of the failure?
On the sensor, electronic summed up as: complete failure, failure of fixed deviation, deviation of drift and decline in accuracy the four classes, today electronic also illustrated from four types of sensor fault status and to analyze the causes of sensor fault happened.
Among them, the failure refers to the sudden failure of sensor, measurement, has been to a constant value,
Fault mainly refers to the sensor measurements differ with the real value of a constant constant type of fault, visible from the figure, defective and trouble-free measurement is parallel;
Drift fault is refers to the difference of sensor measurement value and real value q increases with the occurrence of a class of fault at any time;
Drop is refers to the sensor precision measurement ability, accuracy is lower.
Fall, precision grade, measurement of the mean does not change, but the measurement variance changes.
Fixed fault and drift bias is not easy to find fault, in the process of failure will cause a series of unpredictable problem, make the control system can not work for a long time.
1, according to degree of sensor fault classification according to the size of the sensor fault degree can be divided into hard faults and soft faults.
Hard fault refers to damage caused by the fault structure, generally larger amplitude, change suddenly;
Soft fault refers to variation of amplitude is small, change slowly.
Hard fault is also called the complete failure, failure measured values are not completely changes over the actual, always maintain a reading.
In the constant value usually is zero or readings.
Fault measurement is roughly a straight and level.
Soft breakdown including data deviation, drift and the decrease of the precision grade, etc.
Soft fault is relatively small, hard to find, therefore, in a sense, the soft failure harm does more harm than hard fault, the harm caused people's attention gradually.
2, according to the fault in the performance of classification according to the failure of performance can be divided into intermittent fault and permanent fault.
Intermittent failures and downs;
Permanent failure after failure, can't return to normal.
3, according to the classification of fault occurrence, development process, according to fault occurrence, development process can be divided into mutations fault gentle change.
Fault signal mutation rate changed;
Graded fault signal change rate is small.
4, according to the cause of the fault classification according to the cause of the problem can be divided into deviation fault, fault, open circuit fault, drift fault, fault, periodic interference, nonlinear dead zone of failure.
Deviation of failure of the cause of the problem is: the bias current or bias voltage, etc. ;
Impact failure of the cause of the problem is: the random disturbance, power supply and ground surge, electric spark electric, D/A converter of burr, etc. ;
Open circuit failure of the cause of the problem: signal wire is broken, the chip pin didn't even fine;
Drift failure of failure reasons: temperature, etc. ;
Fault of the cause of the problem: pollution caused by the bridge road corrosion, short circuit, etc. ;
The cause of the problem: periodic interference power supply 50 Hz interference, etc.
Nonlinear dead zone of fault fault reason: amplifier saturation, containing nonlinear link, etc.
In addition, from the perspective of modeling, simulation, can be divided into failure of multiplicative and additive.
To offset fault, in the original signal with a constant or random small signal;
For impact interference, can be in a pulse signal superimposed on the original signal;
For fault signal is close to zero;
A maximum open-circuit fault, close to the sensor output signal;
Drift fault signal to a rate offset the original signal;
Periodic interference failure, a frequency signal superimposed on the original signal.
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