ON DESIGN AND CONSTRUCTION OF MICROPROCESSOR BASED REMOTE SPEED MEASUREMENT, MONITORING AND CONTROL OF D.C MOTOR
BY
JIMOH SAHEED ADESHINA M.ENG./SEET/14/5303
DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING FEDERAL UNIVERSITY OF TECHNOLOGY, MINNA, NIGER STATE
SUPERVISPOR: DR. JACOB TSADO AND DR. ABRAHAM USMAM
SEPTEMBER, 2016
CHAPTER ONE INTRODUCTION 1.1 BACKGROUND OF STUDY The word Tachometer originated from Greek Ταχος, tachos, "speed", and metron, "measure". Tachometer is a sensor and measuring device that can measure the revolution speed of the rotating objects. Tachometers are very useful in monitoring and controlling the Motors in industrial automation, such as in manufacturing plants of industries like chemical, pharmaceutical and textile or it may be a flat-belt and flow-control application. Speed of a motor is one of the important factors to be considered while dealing with dc motors. It determines the power drawn by the motor, efficiency, loading, etc. Also if the machine runs above the rated speed, it might damage or even burn off the machine. So knowing about the speed of a machine is inevitable in order to calculate or control the speed (Nitin Singh and Raghuvir S. Toma, 2013).
It is utilized for measuring the revolution speed of rotating object, for example, shaft or disk, in the motor of the engine vehicles or in different machines where rotation speed is the main impetus. Tachometer is a gadget utilized for measuring the revolution of an object in a given interval of time. Generally it is expressed in revolution per minute or RPM.
Prior tachometers are simply mechanical where the revolution is sent to the tachometer through mechanical coupling (cable or shaft), the rpm is determined gear mechanism and it is shown on a dial. With the coming of current electronics, the tachometers have changed a considerable measure. This anticipated is around a contactless advanced tachometer utilizing 8051 microcontroller. The rate at which the motor spin can be additionally controlled and monitored utilizing the same circuit.
The use of this device is of vital significance for measuring the rotating speed of the shaft or the motor in each vehicle. Given this, this device empowers the driver of the motor vehicle to track the rotating speed and with that to adjust throttle and the gear to the driving conditions. This is vital on the grounds that if the vehicle continues running under prolong speed, it can prompt insufficient lubrication. The insufficient lubrication can influence the work of the engine of the motor and in most pessimistic scenario; it can bring about a breakdown. Hence tachometer is key part of any rotating object.
The utilization of this measuring device is much more extensive. In particular, the tachometer is utilized as a part of: Marine fleet, for measuring the rotating speed of the marine diesel machines on the board ships. This device demonstrates the bearing towards which the boat turns. Broad range of vehicles, for example, automobiles, tractors, tuck airplanes, trains and other light rail vehicles. In Medicine, the device known as haema-tachometer is utilized for evaluating the blood flow rate and numerous laser instruments and devices (Michael Thomas 2015). The traditional Tachometers require contact between the device and the rotating body; there are numerous circumstances where the immediate contact between the tachometer and the device under scrutiny is impractical. To manage such circumstances we require a tachometer which doesn't require direct contact with the rotating body, such tachometers are known as Contact-less Tachometer. Contact less tachometer is a device used to measure speed of a motor by counting the number of rotations per second of a rotating shaft using micro controller. As the name indicates, it can very accurately measure the rotational speed of a shaft without even touching it. This is interesting because making direct contact with the shaft is not an option, and will reduce the speed of the shaft giving faulty readings. This can also be employed to measure the speed of motors which are at unreachable places. Now and again the contact-less tachometer exclusively does not fill the need, as on account of uses where consistent monitoring and control of the RPM is required and the test item is set far from the observing station, in such cases we require a Tachometer which can send the measured value to a remote processing unit. Considering such circumstances, the capacity of sending radio frequency RF signal is likewise added to this configuration by utilizing RF ICs whose average scope of transmission is around 30 meters, which can be effortlessly expanded by utilizing more refined ICs.
Digital Tachometers are used for precise measurement, monitoring and control of all time related quantities, which can be converted into a proportional frequency using appropriate sensor. For non-contact tachometers optical sensors are most suitable especially the reflective optical sensors. The design proposed in this project makes use of the reflective infra-red IR sensor, which is used to convert the angular velocity of the rotating body into corresponding frequency. Once the Frequency corresponding to angular velocity is known it can be used to calculate the RPM using any one of the following methods: direct pulse counting, single pulse time measurement, constant elapsed time (CET), and pulse time measurement using a variable number of counted pulses (Bonert Richard 1989).
