Algorithm and First VI

Objective

The objective is to explore LabVIEW by leveraging a simple algorithm, the use of data and the development of temperature conversion and linear interpolation algorithms for calculating psi from a given temperature.

Introduction

Your program will calculate the resultant saturated pressure of our mythical vessel of special fluid and air to a global variable vesselPressPsi, from a temperature (degrees Fahrenheit, global variable vesselTempFahr). This temperature represents an electrical sensor input that was converted to engineering units. The linear interpolation algorithm is based on degrees Celsius.

Requirements

Design, Code, Test a VI program which will loop forever calculating the resultant saturated pressure of our mythical vessel of special fluid and air to a global variable; vesselPressPsi, from a temperature (degrees Fahrenheit, global variable vesselTempFahr). Temperature will be provided by using a random number generator. Use some form of a modulus operator to place your random number closer to the range vesselTempFahr (138-158F). [U1] This temperature represents an electrical sensor input that was converted to engineering units. The linear interpolation algorithm and corresponding data tables are based on degrees Celsius (local variable vesselTempCelsius). The program will have two pairs of data points See Appendix A, which provide corresponding pressure for a given Celsius temperature. One data pair is the upper and lower degree Celsius and the other pair is the upper and lower relative saturated pressure for the corresponding temperature. Compute the saturated pressure from the temperature input.

Since temperature in this assignment represents an electrical sensor input, we need to understand some basic constraints with sensors. Sometimes sensors are saturated or at their limits of operations, the sensor may respond (signal) with unknown values outside its working range. This could cause erratic or catastrophic conditions for control systems. This is solved by placing limiter testing at saturation points of sensors. Saturation testing imposes upper and lower bounds on a signal. When the input signal is within the range specified by lower limit and upper limit parameters, the input signal passes through unchanged. When the input signal is outside these bounds, the signal is clipped to the upper or lower bound values.[MDV2]

Algorithm

Not every Temperature input will have a direct corresponding pressure. For example if vesselTempCelsius = 65, which is neither of the known Celsius limits in Appendix A. Linear interpolation is a way to fill in the holes'' in tables. Linear Interpolation is a method of constructing new data points within the range of a discrete set of known data points. Linear interpolation is quick and easy, but at times not very precise, to increase precision is to increase the number of data points with in the know set of data points.

In this assignment, you only have two data points, which represent the upper and lower data range.

Interpolation example with Appendix A:

vesselTempFahr = 147.0

Result of hand test is psi= 0.2978 psi

Design considerations:

Use the debugger to set a known value of Fahrenheit before implementing a random number, if you choose.

The data used to validate your hand calculations become your known data inputs to your code. That is a step in validating your code algorithm.

Deliverables 40pts

VI and Icon:

Student name

Student id

Assignment Name

Description of assignment

Input type / limits of VI

Output type / limits of VI

Appendix A

Temperature - t - (oc)	Pressure - pv - (psia, lb/in2)
60	0.2563
70	0.3631

[U1]Additional 10pts extra credit

[MDV2] [MDV2] Information: bounds/saturation testing information