Innovative Laboratory Projects for a Measurements and Instrumentation Course

A typical Electrical and Computer Engineering Technology program includes a 3-credit upperdivision Measurements & Instrumentation course with an embedded laboratory component. There are three main sections for the course: LabVIEW programming with data acquisition, sensors and signal conditioning, and design of measurement and control systems. Laboratory activities mirror the lecture materials and are designed to reinforce the students understanding of LabVIEW and its data analysis capabilities. Laboratory projects, each consisting of one to two weeks in length, are completed by a team of students, and each team contains no more than two students. Labs covered in this course include the design of a calculator, modeling temperature sensors, and design of signal conditioning circuits. Various measurement systems are also designed, including temperature measurement systems, weighing system using strain gages, distance measurement system using an ultrasonic ranging module, and machine vision system using a USB webcam. Additionally, students design a conveyor control system using a mock-up of a three-station conveyor, and an instrumentation control system for automatically determining the frequency response of a lowpass filter using a digital storage oscilloscope with a built-in waveform generator. Several labs require the design of state machines. The intent for this paper is to provide a detailed summary of several of the above innovative laboratory projects for the course to illustrate measurement and control applications with LabVIEW as the software development environment. For each of the laboratory projects, this paper provides a summary of the contents of student reference materials, lab handouts, and engineering requirements. Project assessment results are provided, and recommendations are included to help ensure student success on each of the projects. Introduction to the Measurements and Instrumentation Course This is a required junior-level course for Electrical and Computer Engineering Technology students. The objectives of the course are for students to be able to1: • Use LabVIEW as a programming language. • Mathematically model sensors using LabVIEW. • Analyze and design signal conditioning circuits. • Design and implementation of measurement and control systems. This course is lab intensive and utilizes LabVIEW with a myDAQ device as a primary vehicle for the design of measurement systems2-4. The course is three credits with two hours of lecture and two hours of lab per week. The lecture content of the course is divided into three primary sections: Programming applications using LabVIEW (7 weeks), Data acquisition, sensors, and signal conditioning (3 weeks), and Design of measurement systems (5 weeks). The lab content of the course is designed to support the material discussed during lecture. Most of the labs are considered design projects since they include a series of engineering requirements. Depending upon the scope of the lab, engineering requirements may include designing a hardware interface, designing a graphical user interface, designing the software architecture for the program, and implementing an operating sequence. Each lab is designed to be completed in one or two weeks by a student team that consists of no more than two students (some students prefer to work by themselves), where students pick their team members at the beginning of the semester. For many of the labs, students are expected to work outside of the scheduled lab time in order to complete the objectives. A listing of the projects for the course is shown below. • Lab 1: Software-defined Calculator (1 week) • Lab 2: Type-K Thermocouple (1 week) • Lab 3: Type-K and Type-J Thermocouple (1 week) • Lab 4: Analog Input for Resistance Measurement (1 week) • Lab 5: Temperature Measurement System using a Thermistor (2 weeks) • Lab 6: Conveyor System with State Machine (2 weeks) • Lab 7: Digital Voltmeter (1 week) • Lab 8: Non-contact Distance Measurement (1 week) • Lab 9: Signal Conditioning Circuit for an RTD (2 weeks) • Lab 10: Measurement System for Applied Mass (1 week) • Lab 11: Machine Vision (1 week) • Lab 12: Instrument Control over USB Interface (1 week) The purpose of this paper is to provide a detailed summary of several innovative laboratory projects for the course to illustrate measurement and control applications using LabVIEW with the myDAQ as the development environment. Temperature Measurement System using a Thermistor The purpose of this lab project (Lab 5) is to use LabVIEW with the myDAQ and a thermistor (part number RL2006-13.3K-140-D1) to design a temperature measurement system. Datasheets for the thermistor were provided to the students. The engineering requirements for the project are listed below. Special features: • Program designed using LabVIEW • Analog input of the myDAQ used for interfacing to the thermistor voltage divider circuit for measuring temperature • Thermistor (part number RL2006-13.3K-140-D1) used as the temperature sensor • Fluke 87 V DMM with the thermocouple probe used as the temperature standard User Interface Requirements: • One numeric indicator showing the temperature in °C Functional Requirements: • Designed operating temperature range: 0°C to 100°C • Implement thermistor equation that converts RT to T. • Temperature measurement range: 25°C to 75°C with accuracy within +/5°C An example of the screen capture of a student’s LabVIEW front panel and block diagram are shown below in Figure 1. For this project, students needed to implement the equation characterizing the relationship between resistance and temperature for the thermistor. Figure 1(b) includes a MathScript Node that determines the resistance of the thermistor (based on the voltage divider configuration) and implements the mathematical equation of the thermistor for calculating temperature in Kelvin from thermistor resistance. Then, the temperature is converted to Celsius and Fahrenheit. Figure 1(a). LabVIEW front panel of Temperature Measurement System using a Thermistor