测量与信号基础英文PPT (36).pdf
Appendix C Introduction to Arduino8.1 Overview of sensor technology8.2 Resistive sensor8.3 Inductive sensor8.4 Capacitance sensor8.5 Magnetoelectric tranducer8.6 Piezoelectric transducer8.7 Hall sensorChapter 8 Principles of sensorsFundamentals of Measurement and Signal Analysis8.8 Photoelectric sensor8.9 Image sensor8.10 Thermalcouple8.11 Fiberoptic sensor8.12 Grating8.13 Biosensor8.14 How to select a sensor8.2 Resistive sensorA resistive sensor is a sensor that converts the measured quantity into the change of resistance.According to the working principle,it can be divided into:potentiometer,resistive strain gauge,sensitive type(thermosensitive,photosensitive,gas sensitive,magneto sensitive,.)Resistor is the simplest electronic component.The measurement of resistance is simple,accurate and has a large dynamic range.Multimeter can measure resistance from 10 to 10 M;the change of resistance can be easily converted to voltage/current by V=I*R.8.2 Resistive sensor1 PotentiometerA potentiometer is a three-terminal resistor with sliding or rotating contacts to form an adjustable resistance voltage divider.It is widely used to measure displacement or angle.8.2 Resistive sensorEquivalent circuit:Left endRight endMoving endLxl L Total lengthl x Displacementl R Total resistancel Rx Brush resistancel kl Resistance per unit lengthLkRlxkRlxRRLxx*ExxL*E0 EExx0E8.2 Resistive sensorExample:Multi-turn/single-turn potentiometer8.2 Resistive sensorLoading effect:ERxRV VRmVoltage measurement x(1)mEELRxxRLEx0LEExx8.2 Resistive sensorTotal resistance of potentiometer：10kLoading resistance：2kMeasurement range：0-45kgMaximum error：15kgKx*EW Raw materialLoadingReal weightVoltageMeasured weight8.2 Resistive sensorKey parameters of potentiometer:1)Linearity 2)Resolution 3)Deviation of the total resistance4)Measurement range5)Temperature coefficient 6)Lifespan8.2 Resistive sensorHow to manufacture potentiometers:PCB potentiometerWire winding potentiometerSchematic diagram8.2 Resistive sensorPotentiometer products：PotentiometerResistance rulerMulti-turn angle measurement8.2 Resistive sensorPrinciple：weight spring deformation displacement potentiometer resistanceRaw materialExample:Automatic weight measurement 8.2 Resistive sensorPrinciple：steel wire number of coils potentiometer resistanceLiquid levelSteel wireExample:Detection of gas reservation8.2 Resistive sensorPrinciple：motor angle potentiometer resistanceExample:steering angle controlDisplayControlConnect Disconnect ScanMeasureTime:Com name:Baud rate:Status:Time:Com name:Baud rate:Status:Connected8.2 Resistive sensorExample:4-wire resistive touch screen8.2 Resistive sensorConnect four pins of the touch screen to A0,A1,A2,A3void setup()Serial.begin(9600);void loop()pinMode(A3,OUTPUT);pinMode(A1,OUTPUT);pinMode(A2,INPUT);pinMode(A0,INPUT);digitalWrite(A3,HIGH);digitalWrite(A1,LOW);int x=analogRead(A0);Serial.println(x);pinMode(A2,OUTPUT);pinMode(A0,OUTPUT);pinMode(A3,INPUT);pinMode(A1,INPUT);digitalWrite(A2,HIGH);digitalWrite(A0,LOW);int y=analogRead(A1);Serial.println(y);delay(200);Demo Arduino code8.2 Resistive sensorExample:Ball control system using touch screen8.2 Resistive sensorEExRRxDIY：LED control by Arduino and potentiometer8.2 Resistive sensorconst int analogInPin=A0;const int analogOutPin=9;int sensorValue=0;int outputValue=0;void setup()Serial.begin(9600);void loop()/read the analog in value:sensorValue=analogRead(analogInPin);/map it to the range of the analog out:outputValue=map(sensorValue,0,1023,0,255);/change the analog out value:analogWrite(analogOutPin,outputValue);Serial.println(outputValue);delay(100);EExRRx8.1 Overview of sensor technologyHomework1.How does a potentiometer work？2.Under what conditions there will be a good linearity between input and output of a potentiometer?3.Give application examples you know about potentiometer.
