Instrumentasi Sistem Pengaturan - Website - 01...Instrumentasi Sistem Pengaturan - 01 1...

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  • Instrumentasi Sistem Pengaturan - 01 1

    Instrumentasi Sistem Pengaturan

    Pengantar Sistem Instrumentasi

    Ir. Jos Pramudijanto, M.Eng.Jurusan Teknik Elektro FTI ITS

    Telp. 5947302 Fax.5931237Email: pramudijanto@gmail.com

  • Instrumentasi Sistem Pengaturan - 01 2

    Objektif

    Mengetahui konfigurasi sistem instrumentasi; Perbedaan dari sensor dan tranduser; Mengetahui pentingnya manfaat pengukuran; Akurasi dari sensor;

  • Instrumentasi Sistem Pengaturan - 01 3

    A Instrumentation systems includes all the components necessary for producing a measurement.

    Instrumentation Systems

  • Instrumentasi Sistem Pengaturan - 01 4

    Bicycle Speedometer

    Sensor: A Magnet attached to one of the spokesTransducer: The Hall Effect device that produces an electrical pulse as the magnet passesSignal Conditioning: A circuit compares the pulses to a timer and determines the period. A correlation based on the measured period and wheel diameter is used to determine velocity.Output Stage: A digital signal is sent to the LCD displays and the velocity appears on the screen

  • Instrumentasi Sistem Pengaturan - 01 5

    Measurement: Comparison between a standard and what we want to measure (the measurand).What is the standard?

    Width of a mans thumb =1 inchLength of a mans foot = 1 footLength of a mans belt = 1 yard

    There is a need for an unchanging standard for physical parameters

    length(m), time(s), mass(kg), temperature(K), etc.

    Other parameters can be defined in terms of these standard parameters (velocity = length/time)Oversight of standards and definitions (IEEE)

    What is a Measurement ?

  • Instrumentasi Sistem Pengaturan - 01 6

    Sensor converts some physical quantity into an electrical quantity

    Transducer converts one form of energy into another

    What is a Sensor and Transducer ?

  • Instrumentasi Sistem Pengaturan - 01 7

    Sensors and Actuators

    Transducers:a sensor is an electronic transducer that converts a physical quantity into an electrical signal,an actuator is an electronic transducer that converts electrical energy into a physical quantity.They are essential to digital control systems.

  • Instrumentasi Sistem Pengaturan - 01 8

    TradeGetting what you pay forGetting parts that fit

    DesignDesign parameters are based on experimental measurement (ex. max. temperature = 140oC)Analysis based on measurement (Testing: Does the part fail under max load at T = 140oC?)

    ControlSafety (stall sensors on an aircraft wing measure lift)Economy (fuel system controls on an automobile)

    Why is Measurement so Important ?

  • Instrumentasi Sistem Pengaturan - 01 9

    Strain gauge

    Strain-gauge Measurement System

  • Instrumentasi Sistem Pengaturan - 01 10

    Oxygen Sensor

    Airflow Sensor

    Water Temperature

    Oil Pressure

    Accelerometer

    CO Sensor

    Automotive Measurement System

  • Instrumentasi Sistem Pengaturan - 01 11

    Ultrasound Transducer

    Biomedical Measurement System

  • Instrumentasi Sistem Pengaturan - 01 12

    Direct comparisonMeasure length with a rulerMeasure mass with a balanceMeasure pressure with a deadweight pressure gage

    Indirect comparisonUse of a measuring systemRequires calibrationMeasure temperature with a thermometerMeasure velocity with a bicycle speedometer

    How Do we Measure with Sensor ?

  • Instrumentasi Sistem Pengaturan - 01 13

    There is always some uncertainty in measurementsUncertainty: A likely bound on the error

    The application prescribes the required accuracySignificant consequencesCore temperature of a nuclear reactor vs. outdoor temperatureFunctionalityMeasurement of lens curvature on eyeglasses vs. curvature of a wide-angle mirror

    Error Definition: Difference between the actual value and the measured valuePrecision errorBias error

    How Accurate is the Sensor ?

  • Instrumentasi Sistem Pengaturan - 01 14

    Precision Error

    RandomCauses measurement to be randomly above or below the the average value

    Estimated by statistical methodsEstimation based on standard deviation

    Example: Darts

  • Instrumentasi Sistem Pengaturan - 01 15

    Bias Error

    SystematicConstant fractional or total error

    Can not be estimated by statistical methodsEstimation based on an understanding of sources of error

    Example: Darts

    Instrumentasi Sistem PengaturanSlide Number 2Instrumentation Systems Bicycle SpeedometerSlide Number 5Slide Number 6Sensors and ActuatorsSlide Number 8Strain-gauge Measurement SystemAutomotive Measurement SystemBiomedical Measurement SystemHow Do we Measure with Sensor ?How Accurate is the Sensor ?Precision ErrorBias Error