step-master lks-1

HM-13009-2
STEP-MASTER LKS-1
Text of learning
how a stepping motor operates
using this demonstration kit
Basic
WELCOME to the Stepping motor world!
Thank you for purchasing
an Oriental Motor
demonstration product.
Contents
Introduction�������������������������������� 3
This demonstration kit is
1 Now, Let’s start! ���������������������������
●
developed for the beginners
1-1
Checking the product
who want to study
1-2
Assemble the disk to the motor
the stepping motor.
1-3
Features of the STEP-MASTER LKS-1
You can easily understand
1-4
Connection
the basics of the stepping motor
2 Let’s drive the motor �������������������������
●
by using this demonstration kit.
2-1
Touch the disk (on the motor shaft) with your fingers when the motor
is stopped.
2-2
Let’s write in your notes about your experience in your words.
2-3
Try to drive or excite the motor
3 What is a stepping motor �����������������������
●
3-1 Construction of the stepping motor
3-2 Theory of driving
3-2-1
Let’s make a paper model
3-2-2
Let’s look at the motion of the motor with the paper model
4
6
8
3-3 Construction of the stepping motor
4 Instruments for driving the stepping motor ��������������� 11
●
4-1 Circuit for driving the stepping motor
4-2 Let’s view the relationship between the movement of the motor and
the electrical pulses.
4-3 Let’s draw the timing chart
5 Let’s create the excitation sequence for moving������������� 14
●
5-1 Set into the controller the data of full-step sequence.
5-2 Let’s drive the motor touching the disk with your fingers.
6 Continuous drive ��������������������������� 16
●
7 Positioning drive ��������������������������� 17
●
8 Basic characteristics of the stepping motor��������������� 18
●
is a registered trademark or
trademark of Oriental Motor Co.,Ltd., in Japan and
other countries.
Copyright Oriental Motor Co., Ltd. 2010
Unauthorized reproduction or copying of all or part
of this Text is prohibited except to use for your own
educational purpose.
2
8-1 Static characteristic
8-2 Dynamic characteristics
9 Let’s play roulette! �������������������������� 21
●
10 Answers������������������������������� 22
●
11 Specifications ���������������������������� 24
●
Introduction
What is Stepping motor
The stepping motor is an
electromagnetic device that translates
electrical pulses into a mechanical
movement. The stepping motor rotates
step by step according to the number
of electrical pulses, as its name shows.
Therefore, it is also known as “ Pulse
motor”. You can easily understand by
imagining the second hand of a clock.
It is understood that the conventional
motor rotates continuously, but the
stepping motor has unique features in
both rotation and stopping.
The stepping motor holds its final
position without any external control.
No other motors have the characteristic
to be able to hold the position
accurately by itself. For example,
a servomotor needs a rotary encoder
and a driver to control positioning.
It is called the “static performance
characteristics” when the stepping
motor is at standstill.
On the other hand, the stepping motor
is driven by controlling the frequency
and the number of electrical pulses.
To rotate continuously synchronizing
the pulses is to move continuously
synchronizing with two or more
stepping motors. This characteristic
of self synchronizing is impossible
when other types of motors are used.
When it is in motion the stepping
motor performance is called “dynamic
performance characteristics”.
Many stepping motors are used in the
fields of office automation machines,
medical devices and machines,
industrial equipment, etc. Thousands of
applications can use the step motor’s
unique performance characteristics.
COLUMN
What is a pulse?
The word “Pulse” is used to
describe an intermittent flow.
The electric intermittent signals
are called “pulses” and are
derived from that meaning.
Electric signals that change
continuously to positive area and
negative area are called “waves”.
An example is a sine wave.
Pulses
Waves
Before using this demonstration kit
Please read the “Instruction manual”
carefully before beginning the learning
process.
The product has been designed and
manufactured for ease of learning.
Do not use this demonstration kit for
any other purpose. Use the product
by persons who are 15 years old or
older. Oriental Motor Co., Ltd. is not
responsible for any damage caused
through failure to observe this warning.
Characteristics, specifications, and
dimensions are subject to change
without notice.
CAUTION
Do not touch any motor when
it is energized in the field.
It is very dangerous due
to high power and high
temperature. It may cause
serious physical damage.
This demonstration kit is
the exception, because it
is specially built and uses
limited power.
3
1
Now, LET’S GET STARTED!
1-1 Checking the product
Verify the list and the items,
which are included in the kit.
1. Text (this book)
2. Instruction manual
3. Model paper pattern
4. Sticker for the disk
5. Stepping motor with mounting base
(LKS-PTM01)
6. Disk
7. Controller (LKS-PTB1)
8. Four AA batteries
9. Battery holder
10. Screw driver
(cross slot – Phillips type)
11. Text CD-ROM
Gather the following items
to assist in assembly.
Tools required:
● Scotch tape,
● Scissors,
● Pushpin.
1-2 Assemble the disk to the motor
1. Install the disk to the motor
shaft.
4
2. Turn the shaft until the
surface of D-cut faces up.
Insert the disk onto the shaft,
keeping the screw head of the
disk on top. Position the disk
where the surface of the disk
and the top of the shaft is flat.
3. Tighten the screw with a
screw driver to push down
onto the surface of the D-cut.
4. Keep the position, pushing
the surface of D-cut tight.
Otherwise the disk will fall off
the shaft during rotation.
1-3 Features of the STEP-MASTER LKS-1
M
●
1 One board controller
● Easy to connect.
L
●
K
●
● Easy to operate
● Easy to see the motor in operation
2 Battery source
Operate anywhere
C
●
I
●
3 Includes demo drive
A
●
Easy to see the motor operation
without any manipulation
J
●
4 Programmable
excitation sequence
Easy to set the excitation sequence
5 Speed adjust
by potentiometer control
B
●
Easy to set the velocity
6 Includes
basic drive mode commands
● Jog drive
● Continuous drive
● Return drive
● CW/CCW switch
E
●
A Indicator of number of STEPS
●
B Switches for sequencing
●
the DATA set
C LEDs for monitoring the operation
●
Green(PWR) = power,
Red (A, B, A, B) = monitor of
excitation,
Yellow = TIM and BUSY signal
D Rotary switch to change
●
the drive MODE
E Rotary switch to set the number of
●
STEPS
F
●
G
●
H
●
F Potentiometer for setting
●
SPEED
G Switch for changing direction
●
(CW/CCW)
H Switch for STARTING or
●
SETTING motion
I Connector for attaching the
●
MOTOR
J Jack for connecting power
●
supply (DC 6V)
K●
L●
M Connectors for
●
production (not for use in this
kit)
1-4 Connection
1) Insert the connector
of the motor into the
connector ●
I of the
controller. Gently push
the connector until you
hear the sound “click” and
confirm the connection
by pulling lightly on the
connector.
D
●
2) Put the batteries into the
holder making sure the plus
and the minus terminals
are correctly aligned.
5
2
Let’s drive the motor
2-1 Touch the disk (on the motor shaft) with your fingers when the motor is stopped.
● Experiment 1
J .
❶ Do not connect the plug to the jack ●
❷ Try to turn the disk with your fingers before connecting the batteries.
❸ Set the switches as showed left.
J of the controller.
❹ Insert the plug from the battery holder to jack ●
The LEDs turn on sequentially after connecting the battery.
DATA●
B :off
STEP-No.●
E :0
SPEED●
F :CCW end
MODE●
D :0
CW/CCW●
G :CW
After the sequence ends, monitor the LEDs ●
C turn on as follows.
●Green LED for Power,
●Red LEDs for phase A and B,
●Yellow LED for TIM signal.
❺ Try to turn the disk with your fingers.
2-2 Let’s write in your notes about your experience in your words
In noting your experience, “why” you feel this way is very important.
Your understanding of your experience will become clearer later when you have more answers.
COLUMN
6
《Example of noting》
Essence of
Mind Learning Process
❶ Why I felt the weak uneven torque when the stepping motor is not
Generally, the human mind
dislikes a lack of understanding
when confronted by important
questions. The mind will
search the memory on both the
conscious and sub-conscious
levels. The action of writing
down the questions makes one
understand them more clearly.
The mind will imprint these
answers more deeply when
exposed to these answers.
This technique of deep learning
is being used in the STEP
MASTER. Please make a lot of
“why” questions to reinforce this
learning process.
❷ Why I felt the strong power and torque when the stepping motor is
energized.
energized.
Don’t you feel the difference of the stepping motor torque clearly between
not energized and energized.
It is called “ exciting the motor” to create the magnetic flux by putting the
current into the windings of the stepping motor.
The power which keeps the rotor static position is called “ holding torque”
when one excites one set of the windings of the stepping motor.
C
●
J
●
B
●
H
E ●
F ●
D ●
G●
●
2-3 Try to drive or excite the motor
● Experiment 2
Keep the plug connected to the jack ●
J .
Demo drive 1
D to position 1. (demo 1)
❶ Set the MODE ●
H button.
❷ Push the START/SET ●
The disk rotates as follows,
CW 1/4 turn x 8 times － then CCW 2 turns.
D
●
H button,
❸ Whenever you push the START/SET ●
the same motion is repeated.
Demo drive 2
D dial to position 2. (demo 2)
❶ Set the MODE ●
H button.
❷ Push the START/SET ●
The disk rotates as follows,
CW 10 steps － then CCW 10 steps.
D
●
Note: 10 steps times 1.8° per step yields a motor shaft rotation of 18°.
COLUMN
CW/CCW
CW is clockwise and CCW is counter clockwise
when seen from the motor’s shaft side.
CW:Clockwise
CCW:Counter Clockwise
Pull out the plug from the jack ●
J .
Let’s start to study the basics of the stepping motor.
Answer the questions on the way.
7
3
Basis of the stepping motor
3-1 Construction of the stepping motor
Basically, a stepping motor consists of a rotor (consisting
of steel laminations and a permanent magnet) and a stator
(consisting of steel laminations and eight windings).
The rotor rotates by the push and pull power of an
electromagnet that is energized by placing current into the
windings.
There are 50 evenly spaced small teeth on the surface of
rotor when seen in detail.
And there are small teeth located on the inside of the stator as
well.
These teeth create high torque and accurate movement.
Windings basically consist of two phases, A and B.
Each phase is divided into A and A or B and B.
Phase A (B) creates an opposite magnetic pole of phase A (B).
There are two groups of A, A, B and B windings, a total of
eight windings are in the stator.
Figure-1
COLUMN
Phase
In the every day world the word “Phase” indicates a
changing proportion such as the phases of the moon.
In the electrical field, “Phase” represents a segment of
the motor winding. It uses alternating current, which
creates some time lag with respect to each other.
For example, there is single phase 120 VAC power
supply in any house. It is popular to use three phase
200 VAC or 400 VAC power supply in factories.
The number of phases of the power supply for the
motor is the same number as the number of groups of
the motor windings.
Single phase power supply
Rotor
ロータ
Three phase power supply
Voltage
電圧
＋
Windings
巻線
Slot
スロット
−
Stator
ステータ
180˚
90˚
0
360˚
270˚
時間
Time
120˚
Single
Phase
単相
120˚
2 phase Stepping Motor
Phase A
A
A
Phase B
B
Figure-2
Ball bearing
ボールベアリング
Rotor
ロータcore
1 1
マグネット
Magnet
Rotor
core
ロータ
2 2
Windings
巻線
Shaft
シャフト
5 phase Stepping Motor
Phase A
Phase D
Phase E
8
phase
EE相
phase
AA
相
Phase B
Phase C
Stator
ステータ
B
phase
D相
D
phase
B相
B
phase
C相
C
3-2 Theory of driving
3-2-1
Let’s make a paper model
1) Cut out the rotor and the stator
from the model paper pattern using
scissors along the cut off line as
shown in figures ⓐ and ⓑ.
2) Place scotch tape on to both the
centers of the rotor and the stator
for strengthening the paper.
3) Put the paper stator on a board or
cardboard, which allows one to stick
in a pushpin.
Place the paper rotor on the paper
stator putting the three points of the
marked line together, and then stick
in a pushpin at the center of the
paper rotor.
3-2-2　Let’s look at the motion of the
motor with the paper model
1) The teeth of phase A are
magnetized when one energizes
the phase A windings.
Then the rotor rotates to a new
position until the lines in the rotor
and stator teeth align.
QUESTION
● Question 1
When the B phase is
energized after energizing
the A phase, how many
degrees does the rotor rotate
in the paper model?
Figure-3
Energization
Facing
● Question 2
“long”
“short”
Which winding should be
energized to rotate in the
same direction at the same
angle after energizing B
phase?
The length of alignment
2) Next, magnetize the teeth of
phase B by energizing the phase B
windings.
Then the rotor rotates to the position
where the rotor and stator teeth align.
Figure-4
Facing
Energization
If you can not answer these
questions, please find the
answers on page 22.
9
3-3 Construction of the stepping motor
● Construction of rotor
● Path of magnetic flux flow
The rotor consists of two parts,
the iron cores with many small teeth
and the permanent magnet, which is
set between these iron cores.
The permanent magnet is
magnetized in the axial direction of
the motor shaft.
Both iron cores are fixed to the
motor shaft, and shifted a half pitch
(3.6 degrees) from each other.
The magnetic flux flow is created
from the winding currents using the
following path.
1: one of the windings,
2: the air gap between stator and
rotor,
3: one of the rotor cores,
4: permanent magnet,
5: another side of rotor core,
6: air gap between stator and rotor,
7: right-angled top end turn of
original winding,
8: return path of stator core,
9: original winding
The magnetic flux has passed
through both the rotor and stator
teeth and the three-dimensional
return path creates a strong torque
from the stepping motor.
Figure-5
Rotor core 2
Rotor core 1
Number of tooth 50
Tooth pitch
7.2°
Windings
Rotor core 2
Figure-6
Rotor core 1
End Cap
Ball Bearing
End Cap
Stator
Neodymium magnet
Shaft
10
Figure-6 shows the various parts of
the hybrid type stepping motor.
4
Instruments to drive the stepping motor
4-1 Circuit for driving the stepping motor
The stepping motor cannot run by
itself continuously, unlike the AC
motor and the DC motor.
It needs electric circuits that
consist of a pulse generator,
a device that excites the stepping
motor winding in the proper
sequence, a power switch and
a DC power supply.
Power supply
It needs two kinds of power
supplies, one for the motor and
the other for the control circuit.
The power supply for the motor
should have enough voltage
and current to meet the motor
specification.
The power supply for the control
circuit needs a regulated voltage
type power supply for example 5
VDC.
This kit uses a normal flashlight
battery (size AA) both for the
drive motor and for the control
circuit for easy operation.
Current switch circuit
This part delivers the current to
the proper winding in sequence
which is controlled by the logic
circuit.
There are many systems, which
can drive the motor. One is the
constant voltage system.
Another is the constant current
system, and a third is the
microstep system.
This kit uses the constant voltage
system for easy understanding.
COLUMN
Caution for handling
the stepping motor
The shaft material is stainless
steel to eliminate any magnetic
flux path of the neodymium
magnet.
Do not over tighten the screw of
the disk because the stainless
steel is a soft material compared
to steel and it will dent the shaft.
Do not disassemble the stepping
motor. It is difficult to reassemble
the motor, because of its tight
tolerance dimensions and
strong magnet flux. The strong
magnetic field of the Neodymium
rotor will cause serious damage
to other items, for example a
bankcard.
Pulse
Generator
パルス発生部
Logic Circuit
ロジック部
Pulse generator
This part creates the pulse train.
It should control the frequency
and number of pulses.
Current Switch Circuit Stepping Motor
パワー部
ステッピングモーター
Logic circuit
This part creates a drive
sequence signal from the input
pulses that includes a speed
command by varying the
pulse generator frequency and
position command by counting
the number of pulses.
11
I
●
C
●
J
●
H
D ●
G●
●
4-2
Let’s view the relationship between the movement of the motor and the electrical pulses.
Please note your questions and thoughts in your own words
as mentioned on page 6.
● Experiment 3
Do not connect the plug to the jack ●
J .
D to position 5. (jog)
❶ Set the MODE ●
G to CW.
❷ Set the CW/CCW ●
❸ Confirm that the connector of the motor is in its proper place ●
I .
Connect the plug from the battery holder to the jack ●
J on the controller.
The monitor LEDs ●
C will light sequentially in the predefined order.
Then, the following LEDs will light.
●Green LED for power, ●Red LED for phase A, ●Yellow LED for TIM
signal. You can recognize which windings are energized by seeing
the LEDs light up on the monitor ●
C.
H button one time.
❹ Push the START/SET ●
The disk rotates 1.8 degrees in a CW direction.
Then turn on ●the red LED of phase B, and turn off the LED of phase A
and TIM.
H button repeatedly. The disk rotates 1.8 degrees
❺ Push the START/SET ●
each time you push the START/SET ●
H button,
and ●the red LEDs for monitoring ●
C the excitation are turned on
in sequence.
●The yellow LED for TIM is turned on when the phase A is excited.
QUESTION
● Question 3
How do you push
the START/SET ●
H
button to rotate the disk
just one full revolution
in 10 seconds?
Let’s try
to do so using this kit.
Push
H button changing the time interval
❻ Next, push the START/SET ●
from fast to slow.
According to the speed of pushing the button ●
H per time period,
the disk rotates fast and slow.
According to the number of times the button ●
H is pushed,
the disk rotates that multiple number of 1.8 degrees correctly.
● Experiment 4
G switch to CCW.
❶ Set the CW/CCW ●
H button 50 times.
❷ Push the START/SET ●
The disk rotates 90 degrees in a CCW direction.
C the excitation are then turned on
●The red LEDs for monitoring ●
in the reverse direction.
times
in 10 seconds
12
4-3 Let’s draw the timing chart
The timing chart shows which
winding and what timing sequence
should be used to excite the
different stepping motor windings.
The Figure-7 shows the timing chart
of CW direction of Experiment 3.
Figure-7
Phase A
Phase B
QUESTION
● Question 4
Draw the timing chart in a
CCW direction using a wave
drive (one phase excitation
for each move).
It is the timing chart of
Experiment 4
Phase A
Phase B
Phase A
Phase B
Phase A
Phase B
● Question 5
How to draw
a timing chart.
Define “+” as a condition of
exciting of the winding, and “0”
as a condition of not exciting
the winding.
The horizontal axis represents
time, every pulse input moves
the plot from left to right.
You can find which winding is
excited by looking at the various
C.
●LEDs on the monitor ●
You should draw the line to the
place “+” when the winding is
excited and to the place “0”
when the winding is not excited
for each step input.
Draw the timing chart in a
CW direction of a full-step
drive (two phase excitation
for each move).
Let’s confirm where the rotor
stops in relation to the stator
teeth by using the paper
model.
Phase A
Phase B
Phase A
Phase B
● Question 6
Is it possible to move only 0.9
degrees?
If it is possible, how do you
excite the windings?
Can you draw the timing chart
of this movement?
Phase A
Phase B
Phase A
Phase B
13
5
Let’s create the excitation sequence for moving
You can select any excitation sequence easily with this kit.
5-1 Set into the controller the data of full-step sequence.
● Experiment 5
COLUMN
1) Set the switches as follows.
Method of excitation
Connect the plug from the battery holder to the jack ●
J .
MODE ●
D to position 8. (data input mode) CW/CCW ●
G to CW.
There are three sequences for
2) Let’s set the sequence data into the controller as follows.
exciting the 2 phase stepping
E dial to “0”.
❶ Set the STEP No.●
motor.
Wave drive (1 phase drive):
◀Then you can see the same number “0”
at ●
A the 7 segment LED.
B to “A=on”, “B=on”, “A=off”, “B=0ff”.
❷ Set the DATA switches ●
This method excites
a single winding each time.
The step angle movement is
1.8 degrees.
It is not popular to use because of
the low torque generated.
on
◀
◀
Full-step drive (2 phase drive):
This method excites
off
two windings each time.
H button.
❸ Push the START/SET ●
The step angle movement is
◀If ●the red LEDs of A and B are turned on, and
A and B turned off, the controller memorizes the
data correctly.
(The inputted data is set when the START/SET
H button is pushed)
●
Next, set the STEP No.●
E dial to position “1” and set the DATA switches ●
B
to “A=off”,“B=on”, “A=on”, “B=off” and push the START/SET ●
H button.
Set the data like this from step number “0” to “7” according to the table below.
The motor’s full excitation sequence is now input into the controller.
1.8 degrees.
It is a popular method of driving
the 2 phase stepping motor.
Half-step drive (1-2 phase drive):
This method excites
one and two windings
alternatively.
The step angle movement is
0.9 degree.
It drives the stepping motor
STEP No.
0
1
2
3
4
5
6
7
smoother than the full-step drive
Phase A
on
off
off
on
on
off
off
on
because of the smaller half step
Phase B
on
on
off
off
on
on
off
off
angle motion.
Phase A
off
on
on
off
off
on
on
off
Phase B
off
off
on
on
off
off
on
on
3) Let’s drive the motor after you complete the setting of the sequence data.
D to position 5. (jog)
❶ Set the MODE ●
H button.
❷ Push the START/SET ●
The motor’s disk rotates and ●red LEDs of the excitation monitor ●
C are
turned on sequentially step-by-step by pushing the button ●
H.
The direction of disk rotation is changed by the CW/CCW ●
G switch.
14
C
●
A
●
B
●
J
●
H
D ●
G●
●
E
●
5-2 Let’s drive the motor touching the disk with your fingers.
● Experiment 6
Connect the plug to the Jack ●
J .
Demo drive 3
D to position 3. (demo 3)
❶ Set the MODE ●
H button.
❷ Push the START/SET ●
The disk rotates as follows.
CW 1.5 rotations – stop for 1 second – CCW 2.5 rotations
Demo drive 4
D to position 4. (demo 4)
❶ Set the MODE ●
H button.
❷ Push the START/SET ●
The disk rotates as follows.
CW 1.5 rotations – stop for 1 second – CCW 2.5 rotations
Probably you noted
“why the smoothness is different between the demo
drive 1 and 2 even if they move in the same way?”
in your notebook.
You felt that the demo drive 4 is smoother than the demo drive 3.
The reason is the difference of step angle between half step
and full step.
The drive data is shown in the table on page 23 for your
reference.
QUESTION
● Question 7
Make the timing chart of the half step
sequences.
Then drive the motor by setting and then
sending the half step data sequence to the
controller.
STEP No.
0
1
2
3
4
5
6
7
Phase A
Phase B
Phase A
Phase B
● Question 8
Make the excitation sequence as follows
without changing the CW/CCW ●
G switch.
Drive 7.2 degree in a CW direction and 7.2
degree in a CCW direction by 1.8 degrees
when you push the START/SET ●
H button
each time.
Then drive the motor by inputting the data
to the controller and energizing the drive.
STEP No.
0
1
2
3
4
5
6
7
Phase A
Phase B
Phase A
You can understand that the stepping motor moves as
a function of the excitation sequence.
Actually, the microprocessor or logic circuits in the driver
control the sequence, so we usually do not care about
the sequence.
Phase B
It is easy for us to give only the pulse sequences to the driver.
But your knowledge about the sequence helps you to apply
stepping motors to wider fields.
15
6
Continuous drive
Let’s drive continuously
1) Pull off the plug of the battery holder from the jack ●
J on the controller.
And insert the plug to jack ●
J again after approximately five seconds.
The data that you made a little while ago will be erased. Load the data,
which the controller contains from the original operation. (This kind of
operation is called “reset”)
2) Set the MODE ●
D to position 6. (continuous)
● Experiment 7
Turn the SPEED potentiometer ●
F in a CCW direction until it stops.
Push the START/SET ●
H button. The disk will start rotating.
Push the START/SET ●
H button again. The disk will stop moving.
This mode 6 operates the motor in continuous drive from the first push
to the second push of the START/SET ●
H button.
Try to drive the motor by changing the SPEED potentiometer ●
F .
You will find the motor can be driven at a lower speed,
but cannot be driven at a higher speed.
(The speed range of the controller is 20Hz to 1040Hz.)
● Experiment 8
Turn the SPEED potentiometer ●
F in the CCW direction until it stops.
Push the START/SET ●
H button. Turn the SPEED potentiometer ●
F
in the CW direction slowly. Speed of the disk will increase slowly. Then
the disk will stop moving with shaft vibration when reaching a certain
speed. It is called “Lose steps condition”. The maximum speed where it
still rotates smoothly is called “Maximum slewing pulse rate”
● Experiment 9
Next, turn the SPEED potentiometer ●
F in the CCW direction very slowly.
The disk will begin to rotate smoothly. You will feel a torque until the disk
stops by touching the disk with your finger. Push the START/SET ●
H button.
The disk will stop. Push the START/SET ●
H button again. The disk will again
start rotating smoothly. The maximum speed at which the motor starts and
stops immediately is called “Maximum starting pulse rate”
Turn the SPEED potentiometer ●
F in the CW direction very slightly until it loses
steps. Push the START/SET ●
H button. The disk will stop. Push the START/
SET ●
H button again. The disk will not start to rotate smoothly. It will oscillate
erratically. The speed setting needs to be reduced, the stepping motor started
and the speed to be gradually increased to achieve this condition again.
The area of speed range that can immediately start and stop a stepping
motor is called the “Start-stop region”. The area of speed range that can
rotate by increasing the motor speed from lower speeds is called the “Slew
range”. The method of driving a motor with increasing and decreasing speeds
is called the “ Slew up and down method”.
16
COLUMN
Temperature of
the stepping motor
There is no torque developed when
exciting the phase A and A together
because both magnetic fluxes are
opposed to each other, however there
are still losses created by the current
in the windings. This condition causes
an abnormal temperature rise in the
motor.
It is same with the B and B phases. Do
not set that sequence. It is not good
for the motor’s safe operation.
The motor heats up due to the copper
winding and iron losses within the
step motor. The allowable maximum
temperature of the motor depends
on the material used in the motor.
The allowed maximum temperature
of a normal stepping motor is 130°C
(266°F). The differential between the
temperature of inside the motor and
outside housing is about 30°C (86°
F). Therefore the allowed maximum
temperature of the motor housing is
100°C (212°F). The motor is safe when
the temperature is 100°C (212°F) or
lower.
However, it is a dangerous temperature
for us. Please do not touch operating
motors in the field.
The motor in this kit is a special motor
that weakens the power to achieve a
safer lower temperature rise.
The temperature rise of the motor
of this kit is 15°C (59°F). It becomes
40°C (104°F) when using the room
temperature 25°C (77°F).
7
Positioning drive
J
●
H
F ●
D ●
G●
●
Let’s try the positioning drive using return mode!
The positioning or index drive commands the number of
pulses to the driver.
Unfortunately, this kit cannot drive the motor by setting the
number of pulses, because the controller does not furnish
the extra switches and displays to set the number of pulses.
But, the controller manages the number of pulses in itself,
so you can experience a positioning drive another way.
1) Pull off the plug from the jack ●
D
J and set the MODE ●
to position 4.
After 5 second, connect the plug to the jack ●
J . (data reset)
2) Turn the SPEED potentiometer ●
F in the CCW direction
until it stops.
● Experiment 10
D to position 5. (jog mode)
❶ Set the MODE ●
H button repeatedly and count
❷ Push the START/SET ●
the number of pushes.
You can push the button as you like, for example 50 times.
The disk rotates following the number of pulses.
D to position 7. (return mode)
❸ Set the MODE ●
Push the START/SET ●
H button.
Then the disk returns to the initial position by rotating
in the opposite direction.
The drive speed of this action is set by the SPEED
potentiometer ●
F . The theory of this action is follows.
The controller memorizes the number and direction when
you manually push the button while driving the motor.
When the mode is changed to position 7 (return mode),
the controller commands the motor drive with the
same number of pulses that is stored in the controller
memory to rotate in the opposite direction.
● Experiment 11
D to position 6. (continuous mode)
❶ Set the MODE ●
H button, then push the START/
❷ Push the START/SET ●
SET ●
H button again whenever you like.
The disk will start rotating and will stop.
D to position 7. (return mode)
❸ Set the MODE ●
Push the START/SET ●
H button.
The disk will rotate in the opposite direction and stop
at the initial starting position.
● Experiment 12
Try a complex driving scheme using the CW/CCW ●
G
switch and the MODE ●
D dial position 5 (jog mode) and
position 6. (continuous mode)
You can change the switch and the dial when the motor
is at standstill.
Drive the motor using these switches and dials freely.
After that, set the MODE ●
D to position 7 (return mode),
and push the START/SET ●
H button.
The disk will rotate back to the initial position quickly.
As you learned in ● Experiment 10, 11 and 12, the
stepping motor can move correctly by counting pulses.
The controller of this kit can memorize ±8388608 pulses.
COLUMN
The patterns of pulses for driving the stepping motor in specific motion profiles.
●Rectangular profile : The method
of driving within the Start-stop region.
An easy and simple way to create
pulse patterns.
●Trapezoidal profile : The method
to drive over a wide range of speeds
including slew range.It is essential
technology to effectively drive the
stepping motor in many applications.
Rectangular Profile
Trapezoidal Profile
Trapezoidal Profile
Rectangular Profile
Muximum Pulse Speed
Acceleration
Pulse Speed
Starting Pulse Speed
Pulse Number
Time
Time
Pulses(image)
Deceleration
Pulse Number
Pulses(image)
17
8
Basic characteristics of stepping motor
The main
two characteristics of
the stepping motor
Let’s study
the two main characteristics of
the stepping motor
by making use of
your experience up to now.
If you want to know
additional information,
please visit our web site.
http://www.orientalmotor.com
COLUMN
What is torque?
8-1 Static characteristic
Torque vs. Position (θ-T) characteristics
● Experiment 13
Turn the disk with your fingers when the motor is at standstill while power on.
You have already experienced this in experiment 1.
The shaft disk returns to the initial position when moving within a ±particular
angle by an external power such as your fingers.
The disk does not return when moved beyond a ±particular angle.
How many degrees is this particular angle?
The Figure-8 shows the characteristic plot of torque vs. position. There is
zero torque when the motor stops in its stable position with no external force.
Increasing the distance from this initial stable position by external force,
a restoring torque is also increasing up to 1.8 degrees.
Then this restoring torque decreases towards 3.6 degrees. The torque is zero
when the position reaches 3.6 degrees again. The torque increases in the
opposite direction when the distance(s) is over 3.6 degrees. The profile of the
torque vs. position plot is nearly a sinusoidal curve. So, the disk on the shaft
can return to the initial position from the distance within ±1.8 degrees.
Try to analyze why the disk behaves so using the model paper.
トルク
Torque
Figure-8
Motors are used as power
sources to move something
instead of using human beings.
The power to move an object in
linear motion is called “Force”,
and the power to rotate an object
is called “Torque”.
The unit of torque is Nm
(Newton-meters) that means the
force at the circumference of the
radius of a one-meter circle.
Question:
Do you know which force is
bigger when using the same
motors of one Nm torque with
two different size wheels on the
ground?
A:20cm outer diameter wheel
B:60cm outer diameter wheel
18
TH
Stable
Equilibrium
安定点
Position
-3.6
-1.8
Unstable
Equilibrium
不安定点
Position
0
+1.8
+3.6
+5.4
+7.2
Angle
角度
-TH
●The position that the motor stopped with zero torque is called “ Stable
equilibrium position”.
●The maximum torque when the disk (rotor) is at the 1.8 degrees position is
called “Holding torque”.
●To move over 3.6 degrees creates an unstable force that leads to “ Losing
steps”.
●The torque that occurs at a standstill condition without power is called
“ Detent torque” or “ Residual torque”. The feeling of low uneven torque
at experiment 1 is this torque. The value of this torque is around 5% of
the holding torque.
COLUMN
How the “TIM” signal used.
When we use a stepping motor, it
needs to recognize the machine’s
“home position” at first, because
the stepping motor system is
an incrementally controlled system.
The methods to recognize the home
position are as follows.
1) Use a limit switch in the machine.
But a limit switch (mechanical or
electrical) is not very accurate.
2) Use a photo switch to realize
which stable equilibrium position
the motor stops by installing a disk
with a 7.2 degree wide slit on
the motor shaft.
But the photo switch is not more
accurate than one step angle (1.8°).
3) Use the “TIM” signal from
the driver logic.
The “TIM” signal is out when the
excitation sequence is step “0”.
The width of TIM signal is 1.8
degrees in full-step sequence and
0.9 degrees in half-step sequence.
We can attain the motor position
within 1.8 degrees with the electrical
and-logic settings of 1) and 2) and 3).
Driver
ドライバ
Motor
トセンサ モーター
Photoフォ
Sensor
駆動機構
Limit
Switch
リミットスイ
ッチ
TIM信号
TIM
Signal
Drive Mechanism
幅のばらつきは大きい
The
position varies widely
Limitトスイ
Switch
リミッ
ッチ
Rotating
回転位置position
Photo
Sensor
フォ
トセンサ
TIM Signal
TIM信号
Width 7.2
degrees or less
幅7.2°
以下
幅1.8°
Width
1.8 degrees
このポイントで止めると
When
stopping at this
1.8°以下の精度で
point,
the home position
動作原点を決める
ことができる
can be set the accuracy
1.8 degrees or less.
19
8-2 Dynamic characteristics
Speed vs. Torque (F-T) characteristics
● Experiment 14
D setting 6 (continuous
Let’s drive the motor by MODE ●
mode).
Touch and brake the disk movement with your fingers
until the disk is stopped.
Does the torque vary depending on the speed when
stopping the disk?
The speed vs. torque characteristics of a stepping motor
is a very simple vertical line.
The speed of a stepping motor is not changed when
changing the load because a stepping motor is
a synchronous motor.
It supports an increasing load until the motor pulls out of
synchronous speed and drops to zero speed.
The torque when the motor loses synchronism is called
“ Pull out torque” at the indicated speed.
We used to make the chart as stepping motor speed vs.
torque that shows the near horizontal line that connects
each pull out torque at various speeds.
The shape of a stepping motor torque vs. speed or
frequency plot is a family of vertical plots or lines that are
traditionally shown by connecting the maximum pull out
torque values in a descending horizontal line.
All motor types except the stepping motor do follow
a descending horizontal line as speed or frequency
increases, for example a DC motor.
The torque where speed is zero is called “Holding
torque”. The speed where torque is zero is called
“Maximum slewing pulse rate“.
You should take the following into consideration when
using a stepping motor.
1) Maximum start-stop pulse rate
Stepping motors cannot start over a certain speed as
you learned in experiment 9.
The maximum start-stop speed when the load is zero is
called “ Maximum starting pulse rate”.
The maximum torque that can be developed when
the motor starts at each speed is called the “Pull in
torque”.
You have to use a trapezoidal speed vs. time drive profile
when using a stepping motor at high speed and high
torque by starting at lower pull in torque ranges and
gradually increasing the speed into the pull out torque
range.
2) Resonance
The motor drives smoothly over all ranges in this kit
when the torque is set to lower values.
But, if you want to achieve maximum output power for
commercial products, there are some points that one
cannot drive smoothly due to vibration problems.
This phenomenon is called “Resonance”.
You should avoid using that area of the torque vs. speed
range.
The solution is to use a mechanical damper or change
the motor system from a 2 phase to a 5 phase stepping
motor.
Figure-9
Torque
TH
Family of Muximum Torque
Muximum Slewing Pulse Rate
Start-Stop Region
Speed
Muximum Start-Stop Pulse Rate
20
Damper
9
COLUMN
How to use the “BUSY” signal.
The stepping motor stops with over-shoot and
under-shoot in the same way as any other types of
motors.
The time during the oscillation period is called the
“Settling Time”.
You should start the next motion after the oscillations
have ceased.
Some controllers have the “BUSY” signal that is output
from start of the pulse to 0.1 second after the end of
pulses.
The “BUSY” signal means that the motor is still moving
and not at zero speed.
You can start the next action immediately after seeing
the end of “BUSY” signal.
Let’s play roulette!
This kit include program for roulette.
Let’s play with roulette
at the end of this learning process.
1) Put the sticker of the roulette
pattern on the rotating disk, and
also put the triangle indication
mark or another method to
point at the number on the
rotating disk.
2) Set the MODE ●
D dial to
position 9.
Set the STEP No.●
E dial to
position 0.
3) Push the START/SET ●
H button.
The disk starts rotating.
COLUMN
Why the torque decreases
when speed goes higher.
The relation of torque and current is proportional.
To drive the stepping motor, it is necessary to change
the current to the windings sequentially.
That means alternating current is input into the motor
windings.
You will understand how the value of current into
the coil changes depending on the frequency.
After some time, push the START/SET ●
H button again.
The disk will stop randomly.
Therefore we cannot control the stopping position.
Please create this motion profile application
to play yourself.
Congratulations!
You have finished the STEP-MASTER LKS-1 successfully.
You have learned the basic motion technology of
the stepping motor using this kit.
Next step, please locate and learn an application using
commercial products.
21
10
Answers
● Question 1
● Question 6
It rotates 1.8 degrees.
Please think about the following when
It is possible to excite 1 and 2 phase
Let’s try to do this with the paper model.
using the paper model. Which way creates
alternately.
When phase A is excited, the center teeth
more torque, Wave Drive or Full-step Drive?
Let’s make sure with the paper model.
of phase A and one teeth of rotor face each
The hint is in the facing line length of the
other, the center teeth of phase B and one
teeth of the rotor and the teeth of excited
teeth of rotor is shifted by a quarter pitch
phase. Also note that in a wave drive only
of teeth. Next, excite phase B, the center
25% of the windings are energized , while
teeth of phase B and one teeth of rotor
50% of the windings are energized in a 2
face each other after a short move.
phase drive.
The angle of this movement is a quarter
pitch of rotor teeth. One pitch of rotor teeth
● Question 3
is 1/50 of one revolution. So, a quarter pitch
Twenty times per one second.
is 1/200 of one revolution.
You should push the button 200 times in
● Question 7
That is 360/200 degrees, which equals 1.8
10 seconds because the motor rotates 1.8
Please compare the table and the timing
degrees. Generally, the equation of step
degrees per one pulse. It means 20 times
chart of ● Question 6.
angle of stepping motor is as follows.
in one second. This is impossible for us. It
You can easily establish the sequence data
needs an electrical controller, for example,
from timing chart immediately.
θ=360/2nZ
θ: step angle n:number of phase Z:number of
rotor teeth
computer, PLC, etc.
● Question 4
The area that is the exciting phase moves
right down in the sequence chart when
rotating in the CW direction.
The case of CCW, the area of the exciting
1pitch
7.2°
1/4 pitch
1.8°
phase moves right up.
Let’s make sure with the paper model.
Phase A
● Question 2
Put the current into the A phase
winding.
Phase B
Phase A
Phase B
Let’s try to do this with the paper model
you have seen from question 1. Putting
● Question 5
the current into A phase next to B phase
Draw the sequence chart for a 2 phase
causes the motor movement to CW by 1.8
excitation pattern.
degrees.
Let’s make sure with the paper model.
Therefore, when driving in the CW direction,
The position of the rotor stopping is in the
we have to excite A-B-A-B one after another
middle of phase A and phase B.
sequentially.
This way of exciting the motor windings
Phase A
is called a “Wave Drive” or “1-phase
Phase B
Drive”. But this sequence is inefficient. It is
popular to drive the step motor by exciting
two phases at once, it’s called “Full-step
Drive” or “2-phase Drive”.
22
Phase B
Phase A
Phase B
STEP No.
0
1
2
3
4
5
6
7
Phase A
on
off
off
off
off
off
on
on
Phase B
on
on
on
off
off
off
off
off
Phase A
off
off
on
on
on
off
off
off
Phase B
off
off
off
off
on
on
on
off
● Question 8
There are two ways to drive the stepping
motor by using the wave drive or full-step
drive.
Do you understand that the stepping motor
can move continuously only by changing
the sequence and not switching direction?
Actually, the method is seldom used in
today’s machines, but the knowledge helps
you to expand applications.
Wave drive
too. By exciting B phase after exciting A
phase the motor moves 1.8 degrees as
Phase A
Phase A
Phase B
STEP No.
0
1
2
3
4
5
6
7
Phase A
on
off
off
off
on
off
off
off
Phase B
off
on
off
off
off
off
off
on
Phase A
off
off
on
off
off
off
on
off
Phase B
off
off
off
on
off
on
off
off
Full-step drive
STEP No.
0
1
2
3
4
5
6
7
Phase A
on
off
off
on
on
on
off
off
Phase B
on
on
off
off
on
off
off
on
Phase A
off
on
on
off
off
off
on
on
Phase B
off
off
on
on
off
on
on
off
11
Specifications
● Specifications
● Dimensions
Item
Dimentions
Specification
Unit
around 305×225×60
mm
around 1
kg
DC 6
V
Mass
Rated Voltage
KIT
Rated Input Current
0.5
A
around 3
Hour
Ambient Temperature
0 ～ 40(32 ～ 104)
°C(°F)
Number of Phases
2
Life of Battery
Step Angle
1.8
Holding Torque
MOTOR
Rotor Inertia
Temperature Rise
CONTROLLER
● Motor
degree
0.1
Nm
3.5×10 -6
kg・m2
around 15(59)
°C(°F)
Inertia of Disk
35×10 -6
kg・m2
Inner Voltage
DC 4 〜 5
V
Excitation Method
( Unit : mm )
80
Unipoler Const. Voltage
Pulse Speed
20 〜 1040
Number of RTN Pulses
±8388608
Hz
102
● Function of the MODE switch
Position
Symbol
Drive Mode
1
DEMO 1
Demo 1
2
DEMO 2
Demo 2
3
DEMO 3
Demo 3
4
DEMO 4
Demo 4
5
JOG
Jog Drive
6
SCAN
Continuous Drive
7
RTN
Return Drive
8
DATA
Input the Sequence Data
9
ROULETTE
Roulette
0
DRIVER
Driver
71
● Controller
DEMO No.
Data of Drive
92
● Data of the DEMO drive
Method of Excitation
DEMO 1
(CW 200Hz 50pulses, Stop 0.2seconds)×8,
Stop 1second,CCW 300Hz 400pulses
Full-step drive
DEMO 2
CW 1Hz 10pulses,CCW 1Hz 10pulses
Full-step drive
DEMO 3
CW 100Hz 300pulses,Stop 1second,
CCW 200Hz 500pulses
Full-step drive
DEMO 4
CW 200Hz 600pulses,Stop 1second,
CCW 400Hz 1000pulses
Half-step drive
120
31
23
ORIENTAL MOTOR U.S.A. CORP.
http//www.orientalmotor.com
Technical Support
Tel (800)468-3982
E-mail [email protected]
ORIENTAL MOTOR (EUROPA) GmbH
http//www.orientalmotor.de
Customer Center
Tel 00800 22 55 66 22
E-mail [email protected]
SINGAPORE ORIENTAL MOTOR PTE LTD
http//www.orientalmotor.com.sg
Customer Support Centre
Tel 1800-8420280
E-mail [email protected]
July 2011
Printed in Japan Printed
May in
2012
Japan