Sensors, Instrumentation & Control

School of Engineering

University of Central Lancashire

Sensors, Instrumentation & Control

(MP 4706)

Exam 2019/20

Open Book Practical Assessment and Reporting

Instructions to candidates:

Attempt all Questions

This is a time-limited open book practical assessment and reporting.

This assessment constitutes 50% of the grade of this module.

You may use any book, personal notes or, design data.

Learning Outcomes

This assignment assesses the level to which the candidate achieves the following learning outcomes:

1- Demonstrate knowledge and critical understanding of sensors and transducers typically encountered in engineering applications.

2. Understand critically the practical aspects of sensor use and type.

3. Demonstrate knowledge and critical understanding of the principles of instrumentation and measurement systems.

4. Demonstrate knowledge and critical understanding in the devise of an appropriate and effective strategy for processing data; virtual instrumentation and virtual simulation.

Time: 24 hours

Sensors, Instrumentation & Control MP4706, Exam 2019/20

Question 1:

1.1 Compare between the zero and 1st order sensors response, give examples for different sensors; support your answer with figures and drawings.

(5 marks)

1.2 Explain the meaning of the following specifications for a typical pressure transducer; support your answer with figures and drawings:

- Pressure Range: 70 – 1000 kPa;

- Temperature Range: -54˚C to +120˚C

- Full Range Output: 40 mV

- Non-linearity and Hysteresis Error: ±0.5% Full Range Output

- Thermal Zero Drift: 0.03 % Full Range Output /°C

- Supply Voltage: 10 V DC

(6 marks)

1.3 During the calibration of a load sensor to identify the effect of temperature at different operating temperatures, you measured the characteristics tabulated in Table 1. Calculate the following parameters for your measurement system:

1. Zero drift/°C

2. Sensitivity drift/°C

Table 1

(4 marks)

1.4 A thermometer that is initially at a stable temperature of 0 ْC, is suddenly placed in a liquid which is maintained at 100 ْC.

• If the 'time constant' is 1 second, what is the temperature value that the thermometer (first-order system) is expected to indicate after this time interval?

• What is the time required to get a reading of approximately 99% from the step input? (5 marks)

Total 20 marks

At

30°C

Load (N)

0

100

200

300

400

Sensor Output (v)

0

1

2

3

4

At

40°C

Load (N)

0

100

200

300

400

Sensor Output (v)

1.5

3

4.5

6

7.5

Question 2:

In your capacity as an instrumentation engineer, a fisherman asked you to help him to build an electronic scale out of an old rod that is sticking to a room ceiling (shown in Figure1.1). Using your background about strain measurement, answer the following:

2.1 Build a load cell utilising WSG (Wire Strain Gauge) measurement by selecting the suitable strain gauge configuration to be mounted on the old rod (shown in Figure 1.1) to measure the strain. (4 marks)

(Figure 1.1)

2.2 State the following:

i. Which type of strain gauge you are going to use, and why? (2 marks)

ii. Steps you are going to do for the WSG Installation. (2 marks)

iii. Factors that could affect the WSG measurements. (2 marks)

iv. The advantages of connecting the WSG configurations as Wheatstone bridge sensing circuit. (2 marks)

v. WSG common resistance values? (2 marks)

2.3 Draw a new WSG configuration on the old rod (shown in Figure 1.1) to compensate the above WSG configuration for temperature effects; The circuit diagram is required. What is the name of the new configuration? (4 marks)

2.4 Draw the wiring diagram used to measure strain for this load cell, including the complete measurement system using USB-6003 or USB-6002 NI DAQ card.

(7 marks)

Total 25 marks

Question 3:

If you like to develop a computer-based DAQ measurement system or that can provide several functions in a Smart Home System, such as climate control or gas leakage detection functions, answer the following for the climate control system function:

3.1 Draw the hardware connections of the system focusing on the pin connections of the system components, so that the system can provide the 'Climate Control' function. The available devices are: (5 marks) Microprocessor-based system (Laptop/PC). Interface board: NI USB DAQ. LM35 Temperature sensor Humidity sensor Micro-switches Variable resistor LEDs Relays Multi-output power supply Include any required passive electronic components

3.2 Draw a flowchart for a program that can achieve both the climate control and gas leakage detection functions. (4 marks)

3.3 What are the factors that should be considered when selecting a DAQ card? (4 marks)

3.4 Discuss the signal aliasing problem and how you can overcome this effect; support your answer with figures and drawings (2 marks)

3.5 What are the steps of conversion of continuous signals to digital values (ADC)? (2 marks)

3.6 Name four types of ADC’s and choose any two to compare between them; what is the ADC type that is used in NI DAQ’s? support your answer with figures and drawings (7 marks)

3.7 Compare between RTD (Resistance Type Device) and Thermocouples temperature sensors; support your answer with examples and drawings. The LM35 sensor can be classified as which type of temperature sensors? (5 marks)

3.8 Give examples of DAQ cards that can be used to measure the following properties and discuss the reasons for your selection.?

1- Displacement

2- Vibration

3- Strain (6 marks)

Total 35 marks

Question 4:

You are to develop a home security system that can be used to monitor a house of two

doors and four windows. The output of the system should present the status of each

location independently and should provide an audible warning in case of any problem -

including the detection of smoke. The available devices are:

− PIC16F877 Microcontroller (given in Figure 4.1)

− two door push button switches

− four window push button switches

− one Motion Detector

− one smoke detector sensor

− eight LEDs

− one buzzer

− Include any passive electronic components required.

According to your study answer the following questions:

4.1 Draw a block diagram for the complete system. (4 marks)

4.2 Using the PIC16F877A microcontroller shown in Figure 4.1, draw the wiring

diagram of the proposed system. Include any necessary electronic components

required for the microcontroller to function correctly; state the function of each

element. (8 marks)

4.3 Draw a flowchart for a program that can achieve the above function. (4 marks)

4.4 Given the pin configuration of the PIC16F877A microcontroller (shown in Figure

4.1), describe the function of the following: (4 marks)

-

- OSC1/OSC2

- RA0

- RD5

(Figure 4.1)

Total 20 marks

____________

MCLR