Design and Development of a Microcontroller-based Versatile Stepper Motor Control System
Chapter One
Objective of the Project
The Objectives of this project are as follows,
- To design and implement a stepper motor controller by programming the microcontroller with a sequence
of actions to carry out as at when due - To design and implement a stepper motor drive or power circuit
- To design and develop stepper motor base experiments to serve as laboratory work for students of tertiary institution
- To interface the stepper motor controller to the stepper motor drive using opto isolators to protect digital circuits from power circuits
- To test the system by performing all the designed experiments with it.
CHAPTER TWO
LITERATURE REVIEW
Review of Related Past Work
Microcontrollers has been a great support in the advancement of effective control of electric conventional motors(AC/DC) since it houses the control software that permits signal flow that enhance electric motor operations. Sequel to the past works on electric motors, it was made known that electric motors undergoes a rotational motion under the influence of electric current[1]. Motor style and size vary as demands for rotational speed (revolution per minute or rpm ), starting torque and other specifications vary simultaneously, most times this depends on the load level attached A solenoid is an elementary device that converts an electrical signal into mechanical motion, usually rectilinear. It is of great importance when dealing with designs that demands straight line movements [2].
The solenoid consist of a coil and plunger with the plunger being in freestanding mode or spring loaded, the coil will have some voltage or current rating and may and may be DC or AC.
Solenoid specifications include the electrical rating and plunger pull or push force when excited by the specified voltage. Some solenoids are rated only for intermittent duty because of thermal constraints; in which case the maximum duty cycle will be specified.
A microcontroller based AC motor control system is a closed loop feedback control system which could be manually or automatically activated depending on the design of the system and the environmental demands. This system when switched on and the signal inputs set, controls the rotational ability of the AC
motor either in speed or direction and there by transferring control to an attached object. The design has separate feedback circuit and undergoes a free run movement and can only be stopped by switching off the system[3]. The AC motor is comprised of a permanent magnet within a magnetic field.
A microcontroller based DC motor control system is a design which transfers control to DC motor attached to an external object to aid the movement of such objects over time. This design comprise a feedback system that indicates the position and rate of rotation of the motor. The DC motor in experiment is attached to a CD plate which has an opening at the edge and this opening allows the transmition of light signal from an LED sensor. This is to dictate and control the speed at which the DC motor rotates [4].
Electric Motors
Electric motors are devices that accept electrical input and produce a continuous rotation as a result. Necessity of electric motors is to enhance the mechanical movement of object in their various applications, having this in mind, there are numerous cases where electrical motors are employed as actuators in process control. Probably the most common control situation is where motor speed drives some part of a process and must be
controlled to control some variable in the process – the drive of a conveyor system for example. These motors can be activated with the help of a microcontroller and microcomputer based procedures [5]. Looking at the three most common varieties of
electric motors which are DC motors, AC motors and Stepper motors.
Dc Motors
The rotation of a dc motor is produced by the interaction of two constant magnetic field. A type of dc motor employs a permanent magnet (PM) to form one of the magnetic fields . The second magnetic field is formed by passing a current through a coil of wire contained within the PM field. This type of wire called
armature is free to rotate. The coil of wire is connected to the current source through slip ring and brushes (called commutator) but the slip rings are split so that the current reverses direction as
the armature rotates[6]. For rotation to occur, the north and south poles of the PM and the
armature are not aligned . thus there will be a torque driving the north from the north and the south from the south, therefore the armature will rotate counter clockwise.
CHAPTER THREE
SYSTEM ANALYSIS
Methodology
microcontroller based stepper motor control with experiments is a project comprising of various steps and modules which has a clear view of the intentions towards actualizing an aim. Having set of modules that will join together to get this work, each of this modules was separately prepared to give a proposed result.
The methods i applied in the design of this project will go a long way to elaborate the various techniques which could be introduced in future control projects. The modules that make up this system are the input interface module, control system module, software module, output interface module and the power module.
Structured Analysis
In designing a defined system, methods are implemented for integrating the different stand alone units. The method or approach of knowing which to design first before arriving to an additive system resultant is termed design approach. For instance, during the individual module design, power module was
considered first because of its need to test and confirm the efficiency of the stepper motor (ie can the power module drive the stepper motor).
The power module comprise of a 220 volt AC by 12 volts AC transformer, a regulator chip (lm7805), an electrolytic capacitor (1000uf), diodes for rectification and the paper capacitors(10pf)
CHAPTER FOUR
SYSTEM DESIGN
System Specification
Bearing in mind the objectives of this work, certain specification were considered in order to achieve a design that could demo our aim. The system was designed in individual modules with each recommending its distinctions. The power consumption level ofthe stepper motor was put into consideration to reduce cost and since a 5volts stepper motor was available then an AT89C51 microcontroller chip is suitable since we can program it to perform all our duties without an external stepper motor control circuit. There are three types of stepper motor which are
permanent magnet, variable reluctance, and hybrid stepper motor, we are going to use a hybrid stepper motor(5vdc) in our design and Table 4.1 explains the stepper motor specification ability and the corresponding figures that defines the range of functionality of the design.
CHAPTER FIVE
SYSTEM IMPLEMENTATION
Hardware Implementation
Chapter four dealt exclusively with the design of all interfaces required to achieve the hardware objectives of the project, the next step is to implement it. The hardware modules to be implemented in this project work are the input interface module, control system interface module, and the output interface module . The components used in the implementation of this project was carefully chosen and arranged to meet up with the expected objectives of the project. Appendix A shows the list of components used during the implementation process.
Input Interface
This module was implemented using four input switches, port three (3) and pins 3.0, 3.1, 3.2, and 3.3 of the AT89C51 microcontroller. The four mentioned switches that allows signal flow once pressed were soldered to the four mentioned pins of port three of the microcontroller (one switch per pin) using a soldering device and the soldering lead. This switches were not directly soldered to the pins rather a Vero board was used as a base for soldering the connection.
CHAPTER SIX
SUMMARY AND CONCLUSION
Summary of Achievements
This system was created out of the need to make available to students of both secondary and tertiary institutions a tool for experiments with stepper motors and also making this device easily accessible with the aid of a user guide and a list of experiments it could offer. This project was achieved at a low cost, though what it will teach the upcoming generation is far much the price and it will stand as a bedrock for better understanding in the application of stepper motors. With this tool made available to our tertiary institutions, there is no doubt that it will boost the know how of the students and by extension improve their capacity to help automate our local
industries
Problems Encountered and Solutions
So many problems were encountered during the development of this project. However through the continuous support of the Supervisor of the project work, guidance from graduated students, remedies to such problems were not far fetched.
One of the greatest challenges was that of decoding the keys. Another aspect of the problems is that of getting the right component for the design work. Some of the components were not found and some do not have immediate replacement in the data books. In such cases, re-design was the only solution.
There was lack of information source at the early development stage, the information obtained from the school library wasn’t enough to equip the amount of information needed for the commencement of this project. Solution was meeting System Engineers outside to seek for books on systems programming.
Thanks to the Internet.
Although a lot was spent on browsing for information, but it helped a long way towards achieving many goals.
Lastly, getting the right code that worked took a lot of time. This is so in the sense that several debugging and testing was undergone before successful results appeared.
Suggestions for Further Improvements
The result of design and implementation of this work yielded the
expected result. However it would be necessary to cite some
areas that need improvement for further implementations. Any such intentions to improve this work should mind power consumption.
Recommendations
It will be of great importance if more time should be allocated to school project. This will go a long way to
helping the student involved to truly participate actively in developing his work.
Another important suggestion is financial support. Government and agencies should come to the aid of the
student carrying out such project work as this financially. This can only be possible if the school will link the student to such agencies and governmental institutions. Another obvious set back on project implementation is the
non – availability of some components. In the light of this money and time wasted in running around for these
components will be reduced if the university laboratories could liaise with external bodies or relevant organizations for the provision of these components.
Provision of basic amenities like well equipped project lab and library were students can get all the available
information and even electronic components at a subsidized rate. Provision of constant supply of power in the project lab, such that students can spend less time in implementation rather than be delayed by power failure.
Contribution to knowledge
This project work was developed using readily available electronics components, thus obviating the need for foreign
exchange expenditure attendant when importing a foreign made variety. It is tailored to the learning needs of undergraduate students of engineering interested in incremental motion control with stepper motors. Seven experiments have also been developed(Appendix I) to enable students grasp the subject matter through hands on practical exercises
Conclusions
A working model of the project was realized at the end of this exercise, This project is highly educative and gives the student an insight of the basic principles of Small Scale Integration (SSI) technology. The task of achieving this goal (the implementation of the project) was not an easy one, but in the end, the primary aim was achieved. Thanks be to God Almighty.
References
- Schertz, Paul (2000), Practical Electronics for Inventors, pp 589-596
- Jung, Walter G.(1983), IC Timer Cookbook, Second Edition, pp. pg 40-41
- Thomas L. Floyd, Electronic Fundamentals Circuits, Devices and Applications, Prentice-Hall International INC. fourth edition. 2007 pp 201-211
- V.K. Mehta, Shalu Mehta (2003), Principles of Electronics, S. Chand and Company Ltd. Ram Nagar, New Delhi. PP 155- 173
- John H., “Electronic Devices”, Prentice Hall, London, (2000: 175) 1st edition, pp 34 – 45
