ABSTRACT
In this paper it is to be highlighted that, the functionality of D. C. motor in combination
with photo device to work as stepper motor. The heart of this system is a photo device as
they have fast response, low cost, compactness and compatibility. The D. C. motor with
simple additional gear arrangement and simple feedback system, which can be control by
simple microprocessor with short instruction, can work as stepper motor. In this
arrangement it is observed that this combination gives comparatively better performance
than stepper motor as low cost, small step angle, less weight, better torque characteristics,
low power requirement, etc. So, this can be the most efficient solution in the future of
smart industrial control, if simple modification is made on the limitation such as brush
maintenance, noise of gears and inertia problem of big DC motors by using brushless DC
motor, by using the helical gear train and by special electrical and mechanical
respectively.
In today’s automatic world the entire machine control becomes “Intelligent”. This
intelligence is offered by the tiny but smart microprocessor. The microprocessor forms
the brain of these automatic machines: it is requires mechanical machine, which
understand the language of the microprocessor i.e. ‘0’s and ‘1’s. For this purpose until we
are using popularly called as ‘Stepper motors’. So today’s formula is
Automation = Microprocessor + Stepper motor
But the cost and the circuit complexity are increasing, although accuracy and precision is
increasing, for which we are paying the price. We are having with an alternative “The
simple D. C. Motor and photo device with simple additional arrangement”. So the new
formula will be
Automation = Microprocessor + D. C. motor + Photo Devices
ADVANTAGES OFFERED BY STEPPER MOTOR: -
1. It can convert the digital pulses fed to it into discrete mechanical movements. For
the movement of the stepper motor it requires the pulses into the stator windings
in proper sequence. The pulses fed are of digital nature either the current is
flowing or not.
2. As the motor works with the digital signal i.e. pulses it can easily interfaced with
the microprocessor or controller. The pulses provided to the windings must have a
definite sequence, which can be easily provided by the microprocessor.
3. Controlling the pulses fed to the motor can easily control of the rotation. The
direction of the rotation is dependent upon the sequence of the pulses fed to the
motor, not on the polarity of the supply so by just reversing the sequence of pulses
fed; the direction of rotation can be changed. This is very easy with help of the
microprocessor, as it only of the programmed software.
4. The speed of the motor or the R.P.M. of the motor is very just the frequency of
pulses or ‘Step rate’ has to be increased which also done through the software.
5. The rotor remains locked in the position in which the last step was taken at any
time two windings are always energized which locks rotor electromagnetically.
6. These motors can be programmed in three parameters: -
1. Direction
2. Speed
3. Number of steps.
7. These motors are having high torque at low R.P.M. The torque is constant
whether the motor is running or standstill.
8. These are special, controllers available for interfacing the Stepper Motors with the
microprocessors, which greatly simplifies and facilitates the working with the
stepper motors.
9. These motors are having high torque is constant whether the motor is running or
standstill.
10. There are special controllers available for interfacing the Stepper Motors with the
microprocessors, which greatly simplifies and facilitates the working with the
stepper motors. Thus after seeing the advantages the main reasons for which the
stepper motors are preferred are as follows.
1. Microprocessor Compatible
2. The direction of rotation is software controlled.
3. The speed is also software controlled.
4. For a given pulse the mechanical displacement is known
(Depends on the mode in which motor operates.)
DISADVANTAGES OF USING STEPPER MOTORS: -
Besides previously mentioned advantages the use of Stepper Motor suffers
from the following drawbacks as
1. These motors are very costly.
2. The R.P.M. hardly crosses the limit of 1000.
3. The dynamic torque of the motor reduces as the speed increases.
4. These motors requires driver circuitry when works along with the microprocessor
which is costly affair.
5. When the motor stands still, two windings remain energized consumes
unnecessary power which is same as it consumes during the running condition.
6. At high loads as the R.P.M increases due to the sleep precision of the movement
diminishes.
7. The main drawback of the Stepper Motor is that the operation is open loop i.e. if
load is intermittent there is no guarantee of the rotation of the shaft and in
programming is it assumes that if pulse is applied rotation is confirmed.
PRINCIPLE OF WORKING: -
As motor start the photo devices the are, transmitter and receiver pair the
pulse according to the stepper of motor. These pulses are monitored by
microprocessor and give the stop signal to motor as the required position achieved
by shaft in combination with proper gear train. This gives us required step angle.
Using this system improvement in minimum step angle, a torque speed
characteristic possible.
ADVANTAGES USING THE SIMPLE STEPPER MOTOR:-
1. Operation is close loop, (i.e. for rotation of the D.C. Motor the rotational
feedback is available and programmer has to make use of this signal in
programming, so ultimately he is always knows whether the motor shaft is
rotating or not.)
2. Cost is less.
3. Power required is less.
APPLICATIONS: -
1. It can be used in all types of automation application.
2. It can be used in Robotics.
3. In printers, graph plotters, automobiles.
4. Several industrial applications
FUTURE DEVELOMPENT: -
1. Instead of using the conventional D.C. Motor one can use brush less D.C.
Motor.
2. Using the helical gear train can reduce the noisy operation.
3. The problem in ease of big D.C. Motors can be over come special electrical and
mechanical modification
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