Student

Hall Effects Tachometer

Engineering Design Process

Executive Summary

This report gives a detailed explanation of the design and installation of Hall Effect Tachometer to a Yunnan metal lathe in order to be used in measuring the spindle speed in revolution per minute. Here, the tachometer systems was developed by use of Arduino Uno DAQ card and the Arduino IDE. This systems was designed by use of industry proven methods and the use of instrumentation test equipment. To accomplish the mission, the working tachometer systems developed was installed on metal lathe to test the design accuracy under different spindle speed.

Background

The Hall Effect sensor is used in the design of the tachometer that will be used in the detection of the magnetic flus density that is attached to the lathe spindle through sensor’s face. The detected magnetic flux density makes the sensor to give an analogue pulse signal as the output and this will be read by the Arduino DAQ card. This pulses will be processed at a frequency of the 38.2 kHz by the use of the internal analogue to digital converter so that it can determine the period between the signal pulses.

The tachometer developed here will be used in the measuring the spindle speed between the ranges of 20-2000 rpm. After measuring the speed, the speed and frequency will be displayed by the help of an LCD unit. In order to meet the requirement of the tachometer developed, the systems will allow the selection of the spindle speed and the cutting feed rate.

Design Summary

The working of the designed tachometer was observed to be inaccurate at low frequencies that need to be corrected in order to avoid the inaccuracies. In this case, the Hall Effect sensor to be used should be that with an internal which is attached the current sensor and the pulse signal that is generated by the gear material in order to increase rate of signal pulses/revolution.

TABLE OF CONTENTS

1. Introduction 4

1.1. Description of the Project 4

1.2. Abstracting the Problem 5

1.3. Division of Tasks 5

1.4. Problems Faced 5

2. Sensor Selection 6

2.1. Identification of the Sensor Type 6

2.2. Performance Test of the Sensor 6

3. Measurement System Implementation 6

3.1. Hardware Configuration 6

3.2. Software Configuration 7

4. Conclusion 7

7. References 9

5. Appendices 10

  1. Introduction

A tachometer is an instrument used in the measuring of the rotational velocity of the shaft and wheel in rpm. Therefore, tachometers are widely used in industrial and automotive in order to monitor the speed of motors, gearboxes and engines. Through that, the driver‘s work is made easier as the optimal throttle speed is selected and thus, the efficiency of the machine is improved. In order to accomplish the role of the tachometer, the measurand is sensed by the sensor and then the results are displayed to the output device such as an LCD by either use of analogue or digital gauges.

    1. Description of the Project

This project is aimed at the designing and the developing of the tachometer that will be used to measure the lathe spindle speed of a Yunnan 1860G. Here, the DAQ card will be used in monitoring the signal pulses of a Hall Effect sensor that detects the magnet which is attached to the lathe spindle. In addition to the DAQ role of detecting the magnet, it will also calculate the frequency and the rpm of the rotation of the spindle and the results will be displayed to the operator through an LCD unit.

Implementation

The Hall Effect tachometer is to be implemented by use of an Arduino starter kit and its components. Here, the Arduino employed is the Arduino Uno which has an Atmel ATmega328 microcontroller. The DAQ card is to be used in the sampling of the analogue signal of the Hall Effect sensor with a help of an internal analogue to digital converter. Here, every rotation of the lathe spindle will lead to a generation of a pulse signal to be read and calculated to the appropriate value for decision making. After the DAQ reading is taken, the frequencies and the spindle speed will be calculated based on the values read. In addition to that, the DAQ will be reading the cycles between each trigger for purpose of determining the period between the pulses. After that, the frequency and speed is displayed on a Student LCD for the operator to read. Figure 1 below shows the process of measuring the Hall Effect tachometer

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: Measuring Process of A Hall Effect Tachometer1Figure

    1. Abstracting the Problem

The output voltage of a Hall Effect sensor is between 0V to 5V. On the other hand, DAQ card converts this analogue signal to a digital signal. Here, the DAQ utilizes the ATmega328 microcontrollers which is internally embedded to convert the analogue signal to digital signal from 0-255 by the use of a 8 bit resolution. In addition to that, the card detects the upslope pulse, the cards detects the value of the voltage from 2.5V to 4.6V which is equivalent to 127 digital signal to 236 digital signal respectively during the passing of the magnet through the sensor.

    1. Division of Tasks

In this project, the designing and the development of the tachometer was done by following number of steps. The first step was the researching on the best sensor to use and the methods that can be used in the measuring speed in order to be compatible with the Arduino DAQ card. After the selection, an electrical schematic for both the tachometer and the Hall Effect sensor was acquired. This was later assembled on the Arduino DAQ and the bread. In addition to that, the software was written in Arduino IDE. In addition that, the software was also debugged by use of instrumentation test equipment.

    1. Problems Faced

There was a problem of signal detection. This was due to the use of the ratio metric Hall effect sensor that had an analogue output which made the signal pulse detection to be incompatible with the Arduino pulse input function, PulseIn().

  1. Sensor Selection

The Hall Effect sensors varies their output voltage with varying magnetic flux density. With respect to that, the Hall Effect sensors are commonly applied in proximity, current, speed and current measurements. The output of this type of sensors in analogue form but this output can be easily be converted to digital with an incorporation of an extra circuitry. With respect to that, the Hall Effect sensors operates in two methods, by placing the magnet on shaft of disc and by position of the magnet behind Hall Effect sensors.

    1. Identification of the Sensor Type

The UGN3503UA is to be used in the generation of the pulse signal as an output to the DAQ Card. This sensor employs the ratio metric linear behaviour in its operation in an a SIP Package. This package has three pins as the ground, supply and output. The output of this sensor is analogue in nature and it is proportional to the magnetic flux density is measured.

    1. Performance Test of the Sensor

The Fluke 289 multimeter and a magnet was used in testing the UGN3503U Hall effects sensor. In this case, the sensor was connected to the 5V supply of pin 1, then grounded at pin 2 and then the magnetic density was given as an output from pin3.

  1. Measurement System Implementation

Here, the prototype designed was tested by use of the oscilloscope. In addition to that, the calibration was done within the range of 20-2000 rpm for accuracy purposes.

    1. Hardware Configuration

Here, the tachometer is to be assembled by use of Arduino LCD unit and Uno R3 DAQ and breadboard. Here, the Arduino library code will be utilized by the Arduino and wiring standards so that it will be interfaced with the LCD display unit as result, it will simply the programming assembly. Figure 2 shows the schematic circuit of the Hall Effect Tachometer.

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schematic circuit of the Hall Effect tachometer2:Figure

    1. Software Configuration

In the compilation and programming of the Arduino Uno DAQ card Atmel ATmega328 microcontroller, the Arduino IDE software is used. In this case, the software is used in the monitoring of input signal and that detects the consistent trigger point of the signal during the upslope.

  1. Conclusion

The research and development of the Hall Effect tachometer was successful with the prototype assembled and installed for use on the Yunnan metal lathe. The testing was done by the help of the instrumentation test equipment and later the working systems was tested using the industry standard test equipment for accuracy purposes. From this, the system was able to measure accurately the lathe spindle rpm between 75 and 2000rpm speed ranges. In comparison to the test carried out by the in test equipment, inaccuracy in measuring speed below 75rpm was experienced.

7. References

Allegro Microsystems. (2015, June 3). UGN3503UA Hall Effect Sensor Datasheet. Arduino. (2015, June 5). Arduino Uno. Retrieved from www.arduino.cc: http://www.arduino.cc/en/Main/ArduinoBoardUno

Arduino. (2015, June 5). LiquidCrystal — «Hello World!». Retrieved from www.arduino.cc: http://www.arduino.cc/en/Tutorial/LiquidCrystal

Atmel. (2015, June 4). ATmega328 Datasheet. Retrieved from www.atmel.com: http://www.atmel.com/Images/doc8161.pdf

  1. Appendices

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