EEEN4345 Mini Project 2 PDF

Preview

Summary

Min Project 2: Exploring Rotary Sensors, Data Transmission andControlJahleepha Bailey (EEEN)Mark McAllister (MEEN)Jesus Herrera (MEEN)EEEN 4345: Sensors & SystemsSummer I, 2020Dr. Ruby MehrubeogluMay 22, 2020Table of Contents Experiment 7: The Optical Tachogenerator Objectives Introduction E...

Description

Min Project 2: Exploring Rotary Sensors, Data Transmission and Control Jahleepha Bailey (EEEN) Mark McAllister (MEEN) Jesus Herrera (MEEN) EEEN 4345: Sensors & Systems Summer I, 2020 Dr. Ruby Mehrubeoglu May 22, 2020

2

Table of Contents Experiment 7: The Optical Tachogenerator ................................................................................ 4 Objectives ....................................................................................................................................... 4 Introduction ..................................................................................................................................... 4 Equipment ....................................................................................................................................... 4 Sensors ............................................................................................................................................ 5 Procedure ........................................................................................................................................ 5 Data ................................................................................................................................................. 8 Analysis......................................................................................................................................... 10 Questions....................................................................................................................................... 12 Discussion and Conclusions ......................................................................................................... 13 Experiment 8: The D.C. Tachogenerator .................................................................................. 14 Objectives ..................................................................................................................................... 14 Introduction ................................................................................................................................... 14 Equipment ..................................................................................................................................... 14 Sensors .......................................................................................................................................... 15 Procedure ...................................................................................................................................... 15 Data ............................................................................................................................................... 16 Analysis......................................................................................................................................... 16 Questions....................................................................................................................................... 17 Discussion and Conclusions ......................................................................................................... 17 Experiment 9: The Variable Reluctance Probe......................................................................... 18 Objectives ..................................................................................................................................... 18 Introduction ................................................................................................................................... 18 Equipment ..................................................................................................................................... 18 Sensors .......................................................................................................................................... 19 Procedure ...................................................................................................................................... 19 Data ............................................................................................................................................... 21 Analysis......................................................................................................................................... 22 Questions....................................................................................................................................... 24 Discussion and Conclusions ......................................................................................................... 24 Experiment 10: The Four-Bit Optical Encoder...................................................................... 25

3 Objectives ..................................................................................................................................... 25 Introduction ................................................................................................................................... 25 Equipment ..................................................................................................................................... 25 Sensors .......................................................................................................................................... 26 Procedure ...................................................................................................................................... 26 Data ............................................................................................................................................... 27 Analysis......................................................................................................................................... 28 Questions....................................................................................................................................... 28 Discussion and Conclusions ......................................................................................................... 29 Experiment 11: Data Transmission ......................................................................................... 30 Objectives ..................................................................................................................................... 30 Introduction ................................................................................................................................... 30 Equipment ..................................................................................................................................... 31 Procedure ...................................................................................................................................... 31 Data ............................................................................................................................................... 34 Analysis......................................................................................................................................... 36 Questions....................................................................................................................................... 39 Discussion and Conclusions ......................................................................................................... 39 Experiment 12: Introduction to Control.................................................................................... 40 Objectives ..................................................................................................................................... 40 Introduction ................................................................................................................................... 40 Equipment ..................................................................................................................................... 41 Sensors .......................................................................................................................................... 41 Procedure ...................................................................................................................................... 41 Data ............................................................................................................................................... 43 Analysis......................................................................................................................................... 43 Questions....................................................................................................................................... 43 Discussion and Conclusions ......................................................................................................... 44

4

Experiment 7: The Optical Tachogenerator Objectives In this experiment, the group will utilize the optical tachogenerator. Using an LED, a phototransistor, and the optical disc, speed measurement will be performed by using the frequency and output voltage of the kit

Introduction As seen in Experiment 6, a combination of an LED and a phototransistor can be used to measure changes in an environment or system. The phototransistor recieves the light emitted by the LED and the changes in output voltage can be used to interpret these changes as seen in Figure 1. Experiment 6 used this to measure linear displacement but in this lab, it will be used to measure rotational speed. The rotating body will be in the form of the disc shown in Figure 2. There are four rows of slot of varying lengths which correspond to the proportions of the linear velocity at each radii. To go with these 4 rows of slots, there are 4 pairs of LED’s and phototransistors that line up with each row. As the disc rotates, the solid and slotted portions of the disk pass between the pairs and either blocks the light and allows it through. The phototransistors then output voltage based on the light they receive which can be interpreted to find the rotational speed of the disk. What can also be noted and observed is that the because of ambient light, the phototransistor is always receiving light so even when the transistor is not receiving direct light from the LED, there is still an output voltage.

Figure 1 & 2 – Sche matic diagram with LED and phototransistor (left) and the optical disc (right)

Equipment • • •

TQ SIS Hardware Module Power Supply Test Leads

5

Figure 3 – SIS module

Sensors • •

Optical Tachogenerator LED and phototransistor

Figure 4 – Rotary a ssembly o f the hardware module

Procedure Part A – Photo-Transmissive System 1. Plug 12 V power adapter into the kit and into a wall outlet 2. Using the test leads, connect the kit in the configuration in Figure 5

6

Figure 5 – Initial configuration for use of photo transmissive system

Figure 6 – Close up view of the rotary assemb le, and LED ’s used in this lab . The LED on the far right is G0 and is what will be used in this portion

3. Set the current to the midpoint 4. Align the mark on the disc with the panel on the encoder of the rotary assembly so that the output is 0 V 5. Move the rotary assembly to all positions 1-9 and record the following data: whether the G0 light at the bottom of the kit is on, is the portion of the disk in front of the LED is solid or a slot (Figure 6), and the output voltage Part B – Photo-Transmissive System (Alternative Source Signal) 1. Assemble the kit in the configuration shown in Figure 7

7

Figure 7 – Alternate configuration for use of photo transmissive system

2. Repeat steps 3-5 of Part A and except use the B0 LED at the bottom of the kit instead of G0 record the results 3. Use the results obtained from Parts A and B to complete Table 3 below Part C – Characteristics of Motor Speed 1. Assemble the kit in the configuration shown in Figure 8

Figure 8 – Configuration fo r observing the characteristic of the motor spe ed

2. Turn on the motor 3. Switching the display between input voltage and frequency, use the reference input voltage knob to adjust the input voltage from -5 V to 5 V in increments of 0.5 V and record the frequency at each increment

8

Data Table 1 – Results for gray scale encoder test

Disc Position

Slot or Solid

1 (index) 2 3 4 5 6 7 8 9

Slot Slot Solid Solid Slot Slot Solid Solid Slot

G0 LED on/off On On Off Off On On Off Off On

Output (V) 0.82 0.82 9.94 9.94 0.82 0.82 11.8 11.83 0.82

Table 2 - Results for b inary encoder test

Disc Position

Slot or Solid

1 (index) 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

Slot Slot Solid Solid Slot Slot Solid Solid Slot Slot Solid Solid Slot Slot Solid Solid Slot

GO LED on/off On Off On Off On Off On Off On Off On Off On Off On Off On

Output (V) 12 0 11.9 0 12 0 12 0 12 0 12 0 12 0 12 0 12

9 Table 3 – Results for frequency at corresponding speeds

Speed (Rev/min) 0 200 400 600 800 1000 1200 1400 1600 1800 2000

Frequency (Hz) 0 3.33 6.66 10 13.33 16.66 20 23.33 26.66 30 33.33

Table 4 – Results for spe ed and frequency at corresponding input vo ltage

Input Voltage (V) -5 -4.5 -4 -3.5 -3 -2.5 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

Frequency (Hz)

Speed (Rev/min)

270 240 200 170 132 100 66 33 0 0 0 0 0 30 61 90 125 163 195 230 265

16200 14400 12000 10200 7920 6000 3960 1980 0 0 0 0 0 1800 3660 5400 7500 9780 11700 13800 15900

10

Analysis Part A the Photo Transmissive System

Disc Position vs. Output (G0 LED) 14

Solid, Off Solid, Off

12 Solid, Off Solid, Off

Output (V)

10 8 6 4 2

Slot, On

Slot, On

1

2

Slot, On

Slot, On

5

6

Slot, On

0 0

3

4

7

8

9

10

Disc Position Figure 9 – Excel graph o f the disc position versus the output voltage for G0 LED

Disc Position vs. Output (G0 LED) 14

Slot, On

Slot, On

Solid, On

Solid, On

Slot, On

Solid, On

Slot, On

Solid, On

Slot, On

12

Output (V)

10 8 6 4 2

Slot,Off

Solid,Off

Slot,Off

Solid,Off

Slot,Off

Solid,Off

Slot,Off

Solid,Off

2

4

6

8

10

12

14

16

0 0

18

Disc Position Figure 10 – Excel graph of the disc position versus the ou t put voltage B0 LED

After reviewing the data results from table 1 it can be concluded that the results were close to what was expected. When viewing the output results, the voltage was low when the slot was aligned with the led phototransistor. After one complete revolution there was only to cycles of change.

11 Part B the Photo Transmissive System When analyzing the data recorded on table two there is a pattern to the data and is different than the previous table. In this table the voltage is a constant value of 12 volts for every time it is on whether it is solid or slot, as for when it is off the voltage stays at 0. For this table the cycles increased having a total of 8 cycles back to back rather than the first set of data recorded only two cycles. After calculating and recording the values of the frequency graph 1 was constructed showing a constant increasing linear function showing a pattern by doubling the frequency at every other increase of 200 and increasing by value of ten every 600.

Frequency (Hz)

Photo Transmissive System 35 30 25 20 15 10 5 0 0

500

1000 1500 Speed (Rev/Min)

2000

2500

Figure 11 – Exce l graph of the frequency versu s the motor speed

Motor Speed Characteristics 20000 Speed (RPM)

15000 10000 5000 0

-6

-4

-2

0 2 Input Voltage (V)

4

6

Figure 12 – Excel graph of the motor speed and frequency v s. the input voltage

12

Questions 1. How significant is the output frequency from the optical tachometer? The output frequency is significant in that it is used to measure the disc speeds rotation. 2. Can the optical tachometer be used to measure the position of the disc? No, a tachometer is used to measure speed of the disk, but it does not give sense of direction. 3. If the slots in the disc were shortened, what effect would this have on the results? The resolution of the results changes and the results would be more approximate. 4. Can the SIS optical tachogenerator be used to determine the direction of rotation? Yes, it can indicate the direction of rotation by the polarity of the output voltage. 5. Will the accuracy of the measurement be affected by the level of light emitted from the LED and reaching the phototransistor? Yes, the accuracy of the measurement would be affected by the level of light emitted. 6. Would you expect the accuracy of the optical tachogenerator to drift over a period of time? If so, why? Yes, I would expect the accuracy of the optical tachogenerator to drift over a period of time. In addition to a low frequency response, the photo transistor is also inversely proportional meaning, if the speed of the response decreases the gain increases. The increase in gain can affect accuracy. 7. Describe an alternative optical technique that could be used for measuring speed of rotation. Are there any advantages/disadvantages with this technique compared with the opto-transmissive system used in the SIS? Instead of using a phot transistor we could use a photodiode. Photodiodes have a quicker response time and they can work reversed biased, but they are less sensitive and a smaller output current. 8. Describe a non-optical sensor which could be used for transmissive techniques. A hall effect tachometer is a non-optical sensor that could be used for transmissive techniques. The hall effect sensor uses the frequency of activation to measure speed by an induced magnetic field.

13

Discussion and Conclusions In this experiment, we were able to observe the use of the optical tachogenerator, and the use of an optical transmissive technique, to determine the measurement of rotational speed. Since the rate of change of the output signal state varies with shaft speed, the frequency of the output from the phototransistor can be used to measure the rotational speed. For part A of this experiment, the objective was to read the voltages and determine if the disc was in the slot or solid position. Once we graphed the recorded data for the G0 LED, we noticed that any time the disc was in slot and the led was on, the output voltage was 0V and stayed the same. When the disc was in solid and the led was off, the voltage would slightly increase as each pass happened. In part B, the same criteria applied but this time we looked at the B0 LED. We observed a pattern, seen in figure when the disc was solid/slot and led was on/off. And unlike the G0 LED, the output voltages remained consistent.

14

Experiment 8: The D.C. Tachogenerator Objectives In this experiment, the group will take data recorded in Experiment 7 and use it with a DC Tachogenerator in order to record voltage output generated. Plots and tables will be generated that show how this voltage output changes with changes in rotation velocity of the motor.

Introduction A tachogenerator is a device used to convert mechanical rotational energy of a body into electrical output. Figure 1 shows a ba...