Prof. D.K. ChaturvediDept. of Electrical Engineering

D.E.I. (Deemed University)Dayalbagh, Agra

LabVIEW and Its Applications

LabVIEWLabVIEW-Laboratory Virtual Instrument Engineering Workbench

LabVIEW programs are called Virtual Instruments(VIs) as they imitate physical instruments. Graphical Programming language. We can build user interface called front panel with controls and indicators.

ADVANTAGE Higher Modular code User friendly interface Easy to use development environment Provides the capability to build instruments as per our requirements. No obsolescence Cost effective instruments.

Front Panel (User Interface)

Block diagram(Programming Window)

Suppose we are interested to measure the following parameters of a periodic signal

RMS value of the voltageAverage valueFrequencyTrue shape of the waveform

To measure the above parameters, we need the following equipments:

Function generator AC voltmeter Frequency meter Phase angle CRO

We will prefer to measure the above parameters by a single instrument

Generating a periodic signal and measuring parameters of the signal by labview

Labview is a graphical programming system designed for data acquisition, data analysis, and instrument control

LabVIEW program can run on PC Windows, Macintosh and VXI systems, and is transportable from one system to another.

LabVIEW uses graphical symbols (icons) to describe programming actions while other language use text for instruction code

LabVIEW programs are called virtual instruments (VIs) because its appearance and operation imitate actual instruments

When started, two windows are open: (i) Front panel, it simulates front panel of physical instruments (ii) the Block diagram shows the internal components of the program

Front panel can contain control knobs, push button, graph, indicators and other controls

The control and indicator are connected to other operators and program blocks

Each program block has different symbol and data type has different colour

What is Labview

When we start LabVIEW, we will see a screen with a few options on it.

o This is front panel.o Here we can input data and view resultso Data can also be inputed through data file or DAQ cards

Right click the cursor on front panel

o There are numeric, Boolean, string, array, graph, and other controls VI.

o Select numeric control VI and place it on front panel

o Select another numeric VI to display measured value

Numeric control

Numeric display

Block diagram window will be used to create VI programs

Program can be made using Inputs and Outputs of Front panel and Objects from Function window

Labview allows user to set breakpoint and examine data inside the program

Click on red dot on tool manu and then set breakpoint on add iconClick run button on block diagram window and select probe tool from tool menuClick three probes on data path. Three windows will open with values on each path.Click run button to see x+y.

Labview program to display square of numbers Open new VI (front panel and block diagram) Select digital numeric control and waveform graph in front panel Now select block diagram window and open function window Select FOR loop (under structure menu) , multiply VI(under numeric menu), Build array (under Array menu) and Write to spread sheet block (under file I/O menu) Connect ‘N’ of FOR loop to numeric control menu, ‘i’ to inputs of multiplier, Output of multiplier to input of build array menu, Output of array to Graph VI and Spread sheet VI. i = 0, 1, 2…… N (Input of digital control), output of multiplier = i*i.

Modeling of Temperature sensor using Labview VI blocks The characteristics equation of a NTC given thermistor RT = R0 exp(β/T- β/T0), RT resistance at any Temp T °K, R0 resiatnce at ° K, β characteristics coefficient (3500-4000°K), the equation can be further written as

ln (RT/R0) = [ β/T – β/T0] and

T = β/[ln (RT/R0 + β/T0]). If we know β, R0 and RT at any temperature T, then it can be used to display temperature directly.

Following components are required to model thermistor using VI

- Sensor data simulator. - Voltage to thermistor resistance converter module. - Calibration & presentation module Warning system - Password protection (if we are interested)

Sensor Data Simulator ModuleTemperature range: 00C to 650C

Corresponding voltage range (Signal Conditioning Circuit Output): 0.45 V to 1.45 V

This voltage range is generated using random number generator VI in numeric menu of Labview

Here 10 random numbers are averaged to get average Vo

To obtain actual Thermistor Resistance RT at temperature T from voltage output the following equation is implemented

RT =((Vi – V0) / V0 ) * Rs

Where RT – Thermistor Resistance at T

Vi – Input voltage (= 5 V)

Rs – Series resistance (= 1 K-ohm)V0 – Voltage across Rs

Conversion of Vo to RT using Labview

RT =((Vi – V0) / V0 ) * Rs

Front panel for RT

Calibration And Presentation ModuleThe calibration module implements following expression:-

T = /[{ln(RT/ R0)}+ /T0] -------- RT Thermistor resistance at T (K)T Thermistor temperature (K)R0 Resistance at T0 (K) Thermistor characteristics constant (K)

Integrated Block Diagram to simulate inverse model of thermistor

Front Panel Of The Developed Application

The Alarm Module Alarm module in the designed application is used to check the variation of

measurand beyond and below certain user specified boundaries. The application will work if the parameter is within range, otherwise it will give the range violation alarm. The design is sensitive to temperature range between 60C and 30C.

Online Temperature Measurement Using Labview

Vi

RTH

R=1Kohm DAQDevice

LabVIEW

Vo

+

-

Real Time Data File

National Instruments DAQ card

Real-time humidity and temperature measurement using Labview

Front panel of the application

LabVIEW APPLICATION

SYSTEMS where LabVIEW is being used during performance evaluation trials

• Parachute systems• Aircraft Arrester barrier System(AABS)• Heavy Drop System(HDS)• Controlled Aerial Delivery System(CADS)• Floatation systems for Space recovery module• Human Space Program(HSP) deceleration system

etc.

For performance evaluation of the various systems developed in ADRDE, Instrumented trials are conducted using Telemetry and Data Acquisition Systems. LabVIEW is used as Data Acquisition and Data Analysis Tool.

Measured ParametersSnatch and Opening Shock of Parachute Steady load and terminal

velocity of parachute systems. Burst pressure measurement of

FloatsImpact measurement Oscillation of payload

Load Profile Acc/Dec Profile OscillationAltitude Profile Rate of Descent

TELEMETRY AND DATA ACQUISITION TELEMETRY

Data Acquired from various sensors are transmitted through wireless channel. At Ground Station, these signals are received,acquired and processed using Data acquisition card and PC with LabVIEW VI.

Receiver Discriminator DAQ Card

Antenna

PC with LabVIEW

ONBOARD DATA ACQUISITIONData from various sensors is recorded using microcontroller based Data Acquisition system. Data is stored in the internal memory of the DAQ system.Stored data is then downloaded to PC using HyperTerminal for post trial Analysis using LabVIEW application.

SENSORMICRO CONTROLLER BASED DATA ACQUISITION SYSTEM WITH STORAGE MEMORY

Data Acquisition

MICRO CONTROLLER BASED DATA ACQUISITION SYSTEM WITH STORAGE MEMORY

PC with HyperTerminal

Data Downloading

ONLINE DATA ACQUISITION SYSTEM Used when parameters to be recorded are easily accessible. Sensors output is directly acquired by PC using

DAQ card and LabVIEW VI

Sensor DAQ CardPC with LabVIEW

Sensor output is acquired and recorded using LabVIEW

Recorded data after data analysis

Impact Measurement using LabVIEW

DATA ANALYSIS USING LabVIEW

Data recorded using DAQ system Data analysis using LabVIEW: Load profile

Data analysis using LabVIEW: Acceleration Profile Data analysis using LabVIEW: Altitude Profile

DEVELOPMENT OF DISCRIMINATORDiscriminator hardware has been replaced by LabVIEW applicationADRDE has a patent for the scheme.

STRAIN MEASUREMENT SYSTEM-PXI BASED DATA ACQUISITION SYSTEM

Four SCXI-1520 modules capable to interface 32 strain gauge bridges and other Wheatstone bridge based sensors.

Used for strain measurement on metallic structure.

NIcRIO Data Logger

Modular Telemetry and data Acquisition system Video Acquisition using LabVISION. Real time application.

Receiver Discriminator DAQ Card

Antenna

PC with LabVIEW

THANK YOU