Mitsubishi Electronics A173SH, A172SH, A171SH User Manual

Positioning Control

Training Manual

Positioning Control

Cautions on Safety

Make sure to read the manuals and pay careful attention to safety when designi ng a system. In practice, pay attention to the following contents and handle any products or dem onstration units correctly.

Cautions on practice

DANGER

• Never touch any terminal while the power is supplied. If you touch a terminal, you may get an electrical shock.

• Turn off the power before connecting / disconnecting units, or opening any safety covers.

• Never insert your hand or any other object into a moving part.

CAUTION

• Never change the wiring or configuration of demonstration euipment without permission or if you are unsure of how to configure a system correctly. Such actions may cause failure, malfuncti on, injury or fire.

• If a simulation unit (such as an X-Y table) generates an abnormal smell or sound, immediately turn off the power switch.

• If you detect any abnormality, immediately turn off the power and contact a qualified engineer.

Positioning Control

Manual number: JY992D89901 Manual revision: A

Date : July 2000

Positioning Control

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product

iii

Positioning Control

Introduction

This manual describes basic oper ation for those who learn positioni ng control for the first ti me, the aim being so that they can get training using demonstration units of Mitsubishi FA equipment.

The following relevant manuals are available and should be referred to

FX-10GM/FX(E)-20GM Hardware and Programming manual JY992D60401 FX-10GM Users Guide JY992D68401

-10GM/FX2N-20GM Hardware and Programming manual JY992D77801

FX FX2N-10GM Users Guide JY992D77701 FX2N-20GM Users Guide JY992D77601 FX-PCS-VPS Win-E Software Manu al JY992D86801

-10GM/FX2N-20GM Connection Manual JY992D81601

Manual Name Number

Positioning Control

Positioning Control Contents

1. The World of Positioning Control...........................................................1-1

1.1 Welcome to the new world! .................................................................................1-1

1.2 Divers ifi e d a c tu a tors..................... .. .. ........................... .. .. ........................... .. .. .....1-2

1.3 Positioning method type......................................................................................1-4

2. Positioning by AC Servo System...........................................................2-1

2.1 When an AC servo system is introduced........................ ........................ .............2-1

2.2 Examples of AC servo systems....................... .. ........................ .. ........................2-3

3. Components of Positioning Control and Their Roles ............................3-1

3.1 Positioning controller ...........................................................................................3-4

3.1.1 Command pulse and feed quantity............................................................................3-4

3.1.2 Command pulse and feed speed ..............................................................................3-4

3.1.3 Setting the acceleration/deceleration time ................................................................3-5

3.1.4 Backlash correction function ........... ...... ....... ...... ...... .................................................3-5

3.1.5 Zero point return function ..........................................................................................3-6

3.2 Servo amplifier and servo motor.......................... ................................................3-7

3.2.1 Positioning control in accordance with command pulse............................................3-7

3.2.2 Deviation counter function.........................................................................................3-7

3.2.3 Servo lock function....................................................................................................3-7

3.2.4 Regenerative brake function .....................................................................................3-8

3.2.5 Dynamic brake function...................................... ...... ....... ...... ....... .............................3-8

3.3 Drive mechanism......................................................................... ....................... .3-9

3.3.1 Concept of drive system movement quantity ............................................................3-9

3.3.2 Setting the target position........................................................................................3-11

4. Advanced Positioning............................................................................4-1

4.1 Interpolation control.............................................................................................4-1

4.2 Other con t ro ls ................................. .. ... .......................... .. .. ........................... .. .. ... 4 -3

5. Actual Positioning..................................................................................5-1

5.1 Demons tr a ti o n E q u ip me n t ..................... .. .. ........................... .. .. ...........................5-1

5.1.1 Basic Set ...................................................................................................................5-1

5.1.2 Comprehensive Set...................................................................................................5-1

5.2 Operation of the demonstration equipment .........................................................5-2

5.2.1 Program example......................................................................................................5-3

5.2.2 Writing the program...................................................................................................5-4

5.2.3 Parameters................................................................................................................5-5

5.2.4 Operation...................................................................................................................5-7

6. Product Line up .....................................................................................6-1

6.1 Position controller ................................................................................................6-1

6.2 Servo am p lif ie r... ........................... .. .. ........................... .. .. ........................... .. .. .....6-5

6.3 Servo moto r ..................... .. .. ........................... .. .. ........................... .. .. ..................6-7

Appendix A:.............................................................................................. A-1

A-1: Tentative Selection of Motor Capacity................................. ........................ .. ......A-1

A-1-1: Motor effective torque...................... ...... ....... ...... ...... ....... ...... ....... .............................A-2

A-1-2: Load inertia moment..................................................................................................A-4

vii

Positioning Control Contents

viii

Positioning Control The World of Positioning Control 1

1 The World of Positioning Control

2 Positioning by AC Servo Sys tem

3 Components of Positioning Control and Their Roles

4 Advanced Positioning

5 Actual Positioning

6 Product Line up

A Appendix A: Tentative Selection of Motor Capacity

Positioning Control

1. The World of Positioning Control

1.1 Welcome to the new world!

The positioning controller, together with the programmable controller, personal computer and operator interface, is one of the four main units of FA (facto ry automation).

Among them, the positioning controller is important as the basis of FA, and regarded as the center of the mechatronics field in which many senior engineers have been playing active parts.

Positioning is all about motion, and motion often involves speed and precision. As speed can be related to productivity, it is an area of much development. But, when the machine speed increases, a problem with the stop precision is often generated. In order to solve this problem, diversified grades of position controllers have been required and developed.

Improvement of the machine efficiency generates immeasurable added value, including reduction of labour and the machine floor area for the same quantity of production.

The World of Positioning Control 1

If there are no problems related to the pos itioning aspe ct of a ma chine, it may mean that the machine is not running most efficiently. Here is where the science of developing an optimum positioning control system comes in.

1-1

Positioning Control The World of Positioning Control 1

1.2 Diversified actuators

• A power source which moves an element in a system is called actuator. A unit which detects a position of a work piece or moving part is called sensor.

• Diversified actuators and sensors, from simple ones to enhanced ones, are used in positioning.

• This paragraph describes representat ive types, their features and weak points.

Pneumatic

• Air source and high grade piping are required.

• High torque is not available.

• Multi-point positioning is complex and very difficult to achieve.

• Change in pos it ion ing is difficul t.

Brake motor

• Positioning mechanism is simple.

• Repeatability is poor.

• Change in pos it ion ing is difficul t.

(When optical sensors or limit switches are used for stop)

Clutch brake

• Frequent positioning is available.

• Life of friction plate is limited.

• Change in pos it ion ing is difficult.

(When optical sensors or limit switches are used for stop)

1-2

Positioning Control The World of Positioning Control 1

Stepping motor

• Positioning mechanism is simple.

• If load is heavy, motor may step out and displacement can occur.

• Motor capacity is small.

• Precision is poor at high speed.

DC servo system

• Positioning precision is good.

• Maintenance is required for motor brushes.

• It is not suitable for rotation at high speed.

General purpose inverter and general

purpose motor

• Multi-speed positioning is available using high-speed counter.

• High precision positioning is not available.

• Large torque is not available at start. (Specialized inverter is required)

AC servo system

• Precision is good.

• Maintenance is not required.

• Positioning address can be easily changed.

• It is compact, and offers high power.

1-3

Positioning Control The World of Positioning Control 1

1.3 Positioning method type

1) There are three types of positioning method

Control method Description Schematic drawing

Two limit switches are

Moving part

Ball screw

Limit switch for changeover to low speed

Limit switch for stop

High speed

Low speed

Movement

distance

Speed control

Limit switch method

provided in places where a systems moving part passes. At the first limit switch, the motor speed is reduced. At the second limit switch, the motor turns off and the brake turns on, to stop the moving part. In this method, because position controllers are not required, the system configuration can be realized at reasonable cost.

(Guideline of stopping precision: Approximately ±1.0 to 5.0 mm)*

B IM

INV

DC0 to 10V

IM: Inductive motor B: Brake INV: Inverter

Position control

Pulse count method

Pulse command method

A position detector (such as pulse encoder) is set up in a motor or rotation axis. The pulse number generated from the position detector is counted by a high-speed counter. When the pulse number reaches the preset value, the moving part stops. In this method, because limit switches are not used, the stop position can be easily changed.

An AC servo motor which rotates in proportion to the input pulse number is used as the drive motor. When the pulse number corresponding to the movement distance is input to the servo amplifier of the AC servo motor, positioning can be performed at high speed in proportion to the pulse frequency.

Pulses are fed back.

PLG

INV

DC0 to

High-speed counter unit

Pulses are fed back.

PLG SM

Servo

amplifier

Command pulse

Position controller

Moving part

IM: Inductive motor PLG: Pulse generator INV: Inverter PLC: Programmable cont rol l er

10V

High speed

Movement distanc e

Moving part

SM: Servo motor PLG: P ul s e generator PLC: Programmable

Movement distance

Ball screw

Low speed

Ball screw

controller

*1 The stop precision shows a value in a case where low speed is 10 to 100 mm/s.

1-4

Positioning Control The World of Positioning Control 1

2) Positioning method and stop precision

Velocity

Stop command

Velocity

Heavy load Small inertia

Stop command

Coasting distance

Speed reduction start Time delay

Light load Large inertia

Dispersion in s to p

Stop

Time

Stop

< Limit switch method >

- When automatically stopping a moving part driven by a motor, stop the motor by a position signal, detected by a limit switch (in general conditions, turn on the brake at the same time).

- The moving part continues by a coasting distance until it completely stops, after the stop command is given. The coasting distance is shaded in the figure.

- The stop precision is equivalent to the dispersion in the shaded area as shown in the figure on the left. The dispersion is affected by the speed when the stop command is given, the load size and the time delay since the stop command is given, until speed reduction actually starts.

Time

Velocity

High speed

Speed reduction command

Dispersion in speed reduction distance

Dispersion in stop

Time

Stop command

- If the required stop precision is not satisfactory when stopping from the normal operation speed, t he most effective method to improve the stop precision is to reduce the operation speed.

- However, if the operation speed is simply reduced, the machine efficiency may also be reduced. In actual operation, the motor speed can be reduced fro m high sp eed to low speed once, then the motor stopped.

1-5

Positioning Control The World of Positioning Control 1

< Pulse count method >

- When a pulse encoder is attached to a moving par t, and the mot or speed is c ontrol led by a number steps while the pulse number is counted, the movement qu antity per pulse is determined in accordance with the relationship between the pulse number generated by one rotation of the encoder, and the movement quantity of the mov ing part (workpiece) realized by one rotation of the motor. The movement quantity per pulse is regarded as the minimum unit for the stop command.

- However, the coasting distance at stop is not eliminated.

< Pulse command method >

- In this method using a servo system, the weak points described above are improved. A pulse encoder is attached to the servo motor, detecting the motor rotation quantity (workpiece movement distance), to continuously and directly control the speed from the high-speed operation to the t arget p osit ion, which all ows the wor kpiece t o stop wi th good precision.

- As the coasting distance at stop is eliminated, the positioning precision is improved.

1-6

Positioning Control Positioning by AC Servo System 2

1 The Wor l d of Positioning Control

2 Positioning by AC Servo System

3 Components of Positioning Control and Their Roles

4 Advanced Positioning

5 Actual Positioning

6 Product Line up

A Appendix A: Tentative Selection of Motor Capacity

Positioning Control

2. Positioning by AC Servo System

2.1 When an AC servo system is introduced

• Positioning can be performed by many diversified methods. Recently, AC servo methods which offer many advantages are often introduced.

• In the positioning system of an AC servo method, a position controller, servo amplifier and servo motor are generally required. The representative system configu ration is shown below.

Servo amplifier

Commercial

power supply

Converter



Smoothing

circuit

Inverter

DC ACDCAC DC

Positioning by AC Servo System 2

Servo motor

Command

pulse

Position

controller

The position controller generates a specified quantity of forward rotation (or reverse rotation) pulses at a specified frequency.

Deviation

counter

Why is the AC servo system attracting attention?

Speed

command

Current

control

The command pulse number is subtracted by the feedback pulse number, and the speed command to drive the servo motor is made from the deviation (accumulated pulse number). When the accumulated pulse number becomes 0, the servo motor stops.

PWM (pulse width modulation) control

AC servo systems are easier to h andle than hydraulic equipment.

Feedback

current

Feedback

The servo motor is equipped with a built-in encoder (pulse generator), dedicated to high speed response, and suitable to positioning control.

PLG

Encoder

pulse

The AC servo system satisfies the needs for multi-model small-lot production through only simple changes in the program.

As an AC servo system can generate large torque, it can satisfy the needs for down sizing and high power.

- Release from oil management

Robots in conjunction with an AC ser vo system can satisfy the needs for labor saving and automation.

- Release from dangerous, hard and dirty working environments

2-1

Positioning Control Positioning by AC Servo System 2

In the latest AC servo systems, conventional wea k points have been improved as follows.

- Though the latest systems are completely digital, they are equipped with parameters in conformance to diversified mechanical specifications and electrical specifications so that simple setting is possible.

- As frequent operation is enabled by a low inertia motor, the maximum torque is increased and the system can be applied to diversified machines.

- The latest systems are equipped with an auto tuning function, with which the servo amplifier automatically detects the load inertia moment and adjusts the gain. This is possible even if the load inertia moment is unknown.

Aspects described below are now incorperated to AC serv o systems which offer marked improvements from previous products.

In FA work place, a downsized AC servo system occupying less space is required!

In accordance with sever operation conditions, a tougher AC servo system is required!

An AC servo system anyone can handle easily is required! Even if the performance is good, the AC servo system cannot be accepted if it is difficult to handle.

Compact and light servo

system

Robust servo system

Easy servo system

An AC servo system givi ng suf f icie nt cost performance is required!

Good cost performance servo

system

2-2

Positioning Control Positioning by AC Servo System 2

2.2 Examples of AC servo systems

• Positioning indicates the operation to move an element, such as a workpiece or tool (dril l or cutter) from a certain position (point) to another target position (point) and stop it with high efficiency and high precisi on.

• In other words, the principle of positioning is the control of speed in accordance with the position, performed to promptly eliminate the remaining distance to the target position. The flexibility to change the target position electrically and easil y is an important requirement.

• Several cases of positioning using an AC servo motor are systemati cally shown below.

Constant feed

In the press/shear process for cutting, punching, etc., the processed material is positioned with high precision to produce a constant sized product.

Tapping

In order to tap a workpiece, "1. Quick feed", "2. Cutting feed" and "3. Quick return" are repeatedly performed.

Drilling in steel sheet

In order to perform processing on a flat face, positioning with high precision is performed by two motors (X axis feed motor and Y axis feed motor).

2-3

Positioning Control Positioning by AC Servo System 2

Index table

The position of the circular table is indexed. The index position is set on the outside (digital switch) or the inside (program). Shortcut drive is performed depending on the index position.

Lifter moving-up/down

As negative load is applied on the servo motor in positioning of the lifter in the vertical direction, a regenerative option is used also. In order to hold the lifter stationery and prevent drop of the lifter by power interruption, a servo motor with electromagnetic brake is used.

Cart travel control

A servo motor is mounted in the travel cart as the drive source. A mechanism such as rack and pinion is adopted to prevent slippage between the wheels and rails.

Carrier robot

After the conveyor stops, the 2-axis servo system and the arm lifting mechanism transfer workpieces to a palette. The workpiece input positions on the palette can be set to many points so that setup change can be easily performed, even if the palette position and the palette shape change.

2-4

Positioning Control Components of Positioning Control and Their Roles 3

1 The Wor l d of Positioning Control

2 Positioning by AC Servo Sys tem

3 Components of Positioning Control and Their Roles

4 Advanced Positioning

5 Actual Positioning

6 Product Line up

A Appendix A: Tentative Selection of Motor Capacity

Positioning Control

Components of Positioning Control and Their Roles 3

3. Components of Positioning Control and Their Roles

Positioning control requires a number of components such as a positioning controller, servo amplifier, servo motor and drive mechanism. This section describes the role of each component.

3-1

Positioning Control Components of Positioning Control and Their Roles 3

Position controller

• Outputs the positioning speed and the movement quantity in command pulses to the servo amplifier.

• Transfers signals between the programmable controller.

• Controls return to the zero point.

Near point dog signal

In some types, the li mit switc h signal is wired to the posit i on controller.

Main circuit

Position controller

Converter

Positioning

command

control

Command

pulse

AC DC DC DC AC

AC power

supply

Smoothing

circuit

Power board

• Improves the power factor and cuts noise.

• Protects the power circuit.

Servo amplifier

Regenerative

brake

Inverter

Dynamic

brake

Parameter

Pulse

magnification

Zero point

return

control

Servo ready

(Electronic gear)

Counter clear

Zero point signal (PG0)

Operation equipment

• Give inputs for manual/automatic mode, start/stop, zero po int return command, manual forward rotation/ reverse rotation and manual pulse generator to the positioning controller.

Deviation

counter

Speed

command

Current

control

PWM (pulse width

modulation) control

Feedback pulse

Feedback

current

Servo amplifier

• Rectifies the AC power of the main circuit into the DC power in the converter, and smooths it in the smoothing circuit. When the DC power is converted into AC power in the inverter, the current supplied to the servo motor is changed by the P WM (pulse width modulation) control in the contr o l circuit.

• The deviation counter receives and counts the command pulses from the positioning controller, subtracts the feedback pulses from them, then drives the servo motor until the accumulated pulse number becomes 0.

3-2

Positioning Control Components of Positioning Control and Their Roles 3

Servo motor

• Dedicated to hi positionin maximum torque and wide variable speed ran 1/1 or more (1/1,000 to 1/5,000).

Servo motor

In the case of large motor

Cooling fan

Servo motor

Encoder

PLG

(pulse generator)

h speed response optimal to

control, has large start torque, large

When a moving element goes beyond a limit switch (LS), the motor stops.

Drive mechanism

Limit switch

(LS)

Speed

reducer

Near point dog switch

Moving element

Ball screw

Limit switch

(LS)

When

required

Electromag

netic brake

Hand held

Programmer

Setting / display unit

• Used to write pro position controller, allows settin

and display of the data.

Personal

Computer

rams to the

Auxiliary device such as c huck, drill and cylinder

Sensor, actuator,

auxiliary device

• The actuator (moving part drive mechanism) is equipped with speed reducer, timin screw and limit switch.

Graphic Operator Terminal

• Diversified auxiliary devices are also controlled in accordance with positionin

• The PLC or the positionin controller also controls a uxiliary devices.

• The auxiliary device operation completed si PLC or the position controller.

belt, ball

nal is output to the

3-3

Positioning Control Components of Positioning Control and Their Roles 3

3.1 Positioning controller

As the positioning con troller gives position comma nds to the servo amplif ier, positioning programs should be created, and parameters defined. The contents related to programs a nd parameters are described below.

3.1.1 Command pulse and feed quantity

There are the following three types of command pulse output modes.

- PLS/SIGN mode

- CW/CCW mode

- A phase/B phase mode

From the three, the CW/CCW mode is picked up for explanation.

• When the servo motor encoder generates 8,192 pulses for one rotation, the command pulse number "8,192" should be output to rotate the servo motor by 1 rotation. The workpiece feed quantity is in proportion to the puls e number.

< Forward rotation command >

Forward rotation pulse output

Reverse rotation pulse output

< Reverse rotation command >

Forward rotation pulse output

Reverse rotation pulse output

3.1.2 Command pulse and feed speed

• When the servo motor encoder generates 8,192 pulses for one rotation, the command pulse frequency (speed) "8,192 pulses/s" should be output to rotate the servo motor by 1 rotation per second.

Forward rotation pulse output

R e v ers e ro ta tio n pulse output

-1 -2

Pulse number output per

second (frequency)

(8192) pulses

(-8192) pulses

(

8192)

pulses

• Decrease the pulse frequency to rotate the servo moto r at lower speed.

• Increase the pulse frequency to rotate the servo motor at higher speed.

3-4

Positioning Control Components of Positioning Control and Their Roles 3

3.1.3 Setting the acceleration/decelerat ion time

• When the start command is given, acceleration, operation at constant speed and deceleration are performed for positioning. Set the accelera tion time and the deceleration time in the parameters.

Parameter:

Speed

Max. speed

Positioning speed

Actual

acceleration

time

Parameter:

Acceleration

time

• This operation pattern is effective during return to the zero point, positioning and jog operation.

3.1.4 Backlash correction functio n

• The positioning controller can output excessive pulses, only when the movement direction is inverted so that the backlash of the mechanical system is cor rect ed.

< Backlash correction >

Backlash

Parameter:

Deceleration

time

Table

Feed screw

Actual

Time

deceleration

time

3-5

Positioning Control Components of Positioning Control and Their Roles 3

3.1.5 Zero point return function

• There are two types of servo motor encoders, incremental type (pulse count method) and absolute type (absolute position detection method).

• Incremental type is constructed so that the current value stored in the position controller does not increase or decrease, even if the workpiece stop position changes by some reason while the power is turned off, theref ore the positioning address is not assured.

• Accordingly, when the power is turned on, the machine should be moved to the reference point to update the zero point address. This operation is called return to zero point.

• Absolute type is constructed so that the current value stored in the position controller increases or decreases if the workpiece stop positi on changes whil e t he power i s turned of f, thus the positioning address is assured. Accordingly, when the power is turned on, return to the zero point is not required. However , when the machine is used for the first time, it should be returned to the zero point so that it recognizes the zero point address.

Zero point

Deceleration time

Creep speed

Zero point

Dog

switch

Dog

Clear signal

The return point of the dog switch should be adjusted

to a midpoint of the zero point signal (1 pulse per rotation of the motor). In this example, the dog length should not be less than the deceleration distance of the machine.

return speed

Initial position

Zero point return direction

Dog

Backward endForward end

< Operation to return to the zero point >

• The zero point return direction, return speed, deceleration time and creep speed are set by parameters in th e positioning controller.

• There are several zero point return methods. For example, when the forward end of the dog reaches the dog switch, the motor resumes its creep speed. At the first zero point signal after the dog re aches the backward end, the deviation counte r clear signal is output and the motor stops.

• The zero point address set by a parameter is written to the current value register of the position controller.

Limit switch

Initial

position

Escape operation

Dog

switch

Zero point

• In some models, if the zero point return operation is performed while the work piece is stopped beyond the dog switch, the machine moves once until the limit switch is actuated, inverts the direction, then returns to the zero point again (dog search function, zero point return retry function).

3-6

Positioning Control Components of Positioning Control and Their Roles 3

3.2 Servo amplifier and servo motor

The servo amplifier controls the movement quantity and the speed in accordance with commands given by the positioning controller. The servo motor transmits rotation to the drive mechanism after receiving a signal from the servo amplifier.

3.2.1 Positioning control in accordance with command pulse

• By PWM (pulse width modulatio n) control, performed to the servo amplifier main circuit with regard to the position co mmand and the speed command, in accordanc e wi th the command pulses of the position controller, the servo motor is driven. The rotation speed and the rotation quantity are fed back from the encoder attached to t he servo motor.

3.2.2 Deviation counter function

• The difference between the command pulses and the feedback pulses counted by the deviation counter in the servo amplifier is cal led accumulated pulses.

• While the machine is operating at a constant speed, the accumulated pulse quantity is almost constant. During acceleration and deceleration, the accumulated pulse quantity changes more dramatically.

• When the accumulated pulse quantity becomes equivalent to or less than the specified quantity (in-position set value) after command pulses have stopped, the servo amplifier outputs the positioning completed signal. The servo motor continues operation even after that. Then, when the accumulated pulse quantity becomes 0, the servo motor stops. The time after the servo motor outputs th e positioning completed signal, until it stops is called stop settling time.

Speed

Accumulated

pulses

Stop settling time

3.2.3 Servo lock function

• The servo motor is controlled so that the accumulated pulse quantity counted in the deviation counter becomes 0.

• For example, if an external force for forward rotation is applied on the servo motor, the servo motor performs the reverse rotati on operation to eliminate the accumulated pulses.

Command speed

Motor speed

The accumulated pulse quantity is 0, and positioning is completed.

Time

Accumulated pulses in deviation counter Servo motor

Minus pulses Reverse rotation operation

Plus pulses Forward rotation operation

0 (zero) Stop

3-7

Positioning Control Components of Positioning Control and Their Roles 3

3.2.4 Regenerative brake function

• During deceleration, because the servo motor rotates by the load inertia of the drive mechanism, it functions as a generator and electric power returns to the servo amplifier. The regenerative resistor absorbs this electric power, and functions as a brake (called a regenerative brake.)

• The regenerative brake is required to prevent regenerative over voltage in the servo amplifier when the load inertia is large and th e operat ion is frequently performed.

• The regenerative resistor is required when the regenerative power generation quantity during deceleration exceeds the allowable regenerative electric power of the servo amplifier.

3.2.5 Dynamic brake function

• When a circuit inside the servo ampl ifi er is di sabled b y a power int er rupti on in the AC po wer of the main circuit or actuation of the protective circuit, the terminals of the servo motor are short-circuited via resistors, the rotation energy is consumed as heat, then the motor immediately stops without free run.

• When the motor stops by elimination of the rotation energy, the brake is not effective and the motor runs freely.

Main circuit AC power supply

NFB

Position

controller

rotations of motor

Converter

AC DC

Deviation

counter

Number of

Inverter



DC AC

D/A

conversion

Motor stop characteristics when the dynamic brake is actuated

When the dynamic brake is not actuated

U V

These contacts of the dynamic brake turn ON when the power is interrupted.

SM PLG

Power: OFF Contacts of dynamic brake: ON

Time

3-8

Positioning Control Components of Positioning Control and Their Roles 3

3.3 Drive mechanism

The drive mechanism converts the rotation motion of the servo motor into the reciprocating or vertical motion through a speed reducer, timing belt, ball screw, etc. to move the machine.

3.3.1 Concept of drive system movement quantity

1) Representative positioning system using AC servo motor *2 In the structure design, parameters (such as ∆ and V

advance.

Moving part

Encoder

Servo motor

Servo

amplifier

Position

controller

Speed

reducer

1 n

: Movement quantity per pulse (mm/pulse)

: Moving part speed during quick feed (mm/min)

: Number of rotations of motor during quick feed (r/min)

: Lead of ball screw (mm/rev)

: Speed reduction ratio

: Feedback pulse number (pulse/rev)

: Command pulse frequency during quick feed (pulse/s)

: Movement quantity per rotation of motor (mm/rev)

) should be determined in

a) The servo motor stops with the precision (±∆ ) which is within ±1 pulse against the

command pulse.

b) The movement quantity of the work piece is

"Output pulses from position controller × ∆ ". The moving part speed is "Command pulse frequency from position controller × ∆ ".

c) Either "mm", "inch", "degree" or "pulse" can be selected as the positioning command

unit. Accordingly, when data suc h as the movement qu antity per pu lse, posit ioning speed or the positioning address in accordance with the positioning command unit are set, the pulse trains calculated inside the positioning controller are output for the target address, and positioning is performed.

3-9

Positioning Control Components of Positioning Control and Their Roles 3

2) Examples of calculation equations a) Movement quantity per rotation of motor (mm/rev)

Movement quantity per

Lead of ball screw (mm/rev) Speed reduction ratio=

rotation of motor

b) Number of rotations of motor (rev/min.)

(The maximum number of rotations is realized during quick feed.)

Number of rotations of motor

Note:The number of rotations of a motor during quick feed should not exceed the rated number of rotations. The moving part speed during quick feed should not ex ceed the parameter "speed limiting value" of the positioning controll e r.

a) Movement quantity per pulse (mm/pulse)

Movement quantity per pulse

b) Command pulse frequency during quick feed (pulse/s)

Command pulse frequency during quick feed

Moving part speed during quick feed (mm/min)

Movement quantity per rotation of motor

Movement quantity per rotation of mot or (mm/rev)

Feedback pulse number (pulse/rev)

Number of rotations of motor during quick feed (r/min)

Movement quantity per

rotation of motor (mm/rev)

Movement quantity per pulse

(mm/pulse)

Rated number of

rotations of

servo motor

Electronic

gear ratio

Note:The command pulse frequency during quick feed should not exceed the maximum input pulse frequency of the servo amplifier.

a) Maximum movement distance

In each of the absolute and incremental methods, the entire movement distance should not exceed the maximum pulse number of the positioning contro ller.

3-10

Positioning Control Components of Positioning Control and Their Roles 3

3.3.2 Setting the target position

In positioning control, the target position can be set by the following two methods. (Available command units are "mm", "inch", "degree" or "pulse".)

1) Absolute method In this method, a point (absolute address) is specified for positioning while the zero point is regarded as the reference. The start point is arbitrary.

Address

100

Address 100

Start point End point

Address 150

Address 300

Address 150

Address 100 Address 150

Zero point

100

Point A

150

Point B

300

Point C

2) Incremental method In this method, positioning is performed through specification of the m ovement direction and the movement quantity while the current stop position is regarded as the start point.

Movement quantity

Zero point

+100

Movement quantity +100

Movement quantity -150

Movement quantity -100

100

Point A

Movement quantity

Movement quantity +100

Movement quantity +50

150

Point B

-100

300

Point C

Start point End point

3-11

Positioning Control Components of Positioning Control and Their Roles 3

3-12

Positioning Control Advanced Positioning 4

1 The Wor l d of Positioning Control

2 Positioning by AC Servo Sys tem

3 Components of Positioning Control and Their Roles

4 Advanced Positioning

5 Actual Positioning

6 Product Line up

A Appendix A: Tentative Selection of Motor Capacity

Positioning Control

4. Advanced Positioning

4.1 Interpolation control

The interpolation function controls two or more axes alternately or simultaneously. Linear interpolation and circular interpolation are usually offered.

Advanced Positioning 4

< 2-axis linear interpolation >

axis

Start point

< 3-axis linear interpolation >

Z axis

Start point

X axis

Speed change in X axis

Speed

End point

X axis

Y axis

< Linear interpolation >

- Linear interpolation controls two or more axes so that the start point and the end point (target position) are connected in the shortest way.

- In this case, the locus is linear.

- Models applicable to 2-axis linear interpolation control [FX-20GM,E-20GM,FX

-20GM AD75P2/P3,AD75M2/M3, QD75P2/P4,QD75D2/D4, A171SH,A172SH,A173UH,A273UH]

- Models applicable to 3 or 4-axis linear interpolation control [A171SH,A172SH,A173UH,A273UH]

- Application examples [Drilling on steel sheet, insertion of parts into PCB, automatic warehouse, automatic crane, etc.]

Time

4-1

Positioning Control Advanced Positioning 4

< Circular interpolation when an auxiliary point is specified >

Auxiliary

line

axis

Start point

< Circular interpolation when the radius is specified >

axis

Start point

< Circular interpolation when the center is specified >

Y axis

End point

X axis

End point

Radius

X axis

< Circular interpolation >

- Circular interpolation controls two or more axes so that the start point and the end point (target position) are connected with circular arc.

- As there are innumerable number of arc locus connecting two points, an auxiliary point, the arc radius, the center or the direction should be specified in addition to the start point and the end point to determine the circular arc.

- Models applicable to 2-axis circular interpolation control [FX-20GM,E-20GM,FX

-20GM AD75P2/P3,AD75M2/M3, QD75P2/P4,QD75D2/D4, A171SH,A172SH,A173UH,A273UH]

- Models applicable to 3-axis circular interpolation control [A171SH,A172SH,A273UH]

Speed

Center

Start point

Speed change in X axis

End point

X axis

- Application examples [Steel sheet fusing, welder, applicator, crane, etc.]

Time

4-2

Positioning Control Advanced Positioning 4

4.2 Other controls

In some models, controls in accordance with diversified special needs such as speed control, position follow-up co ntrol and three-dime nsional interpolation c ontrol shown below are available.

< Speed control >

- After movement starts from the start point, it then continues at the

Start point

X axis

Speed change in X axis

Speed

specified speed until the stop command is input.

- Applicable models [FX-1PG,FX

-1PG AD75P1/P2/P3,AD75M1/M2/M3, QD75P1/P2/P3,QD75D1/D2/D3, A171SH,A172SH,A173UH,A273UH]

- Application examples [Conveyor, carrier unit, roller feed, crane, etc.]

Speed

Constant

quantity

Start point

Speed change in X axis

End point

Time

X axis

< Constant feed >

- After start, a workpiece moves by the specified constant quan tity, but the current value do es not increase even if the operation is repeated.

- Applicable models [FX-10GM,FX-20GM,E-20GM,

-10GM,FX2N-20GM AD75P1/P2/P3,AD75M1/M2/M3, A171SH,A172SH,A273UH]

- Application examples [Press, shear, conveyor, transfer unit, assembly line, etc.]

Time

4-3

Positioning Control Advanced Positioning 4

Y axis

Speed

1000 mm/min

Start point

300 mm/min

5000 mm/min

Speed changeover point

Speed change in X axis

End point

X axis

< Speed changeover control >

- From the start point which is the current stop address, positioning control is performed to the e nd point address while the speed changes at speed changeover points.

- The address for speed change can be determined in advance.

- Applicable models

[FX

-1PG,FX-10GM,FX-20GM,

E-20GM,FX

-10GM,FX2N-10GM, AD75P1/P2/P3,AD75M1/M2/M3, QD75P1/P2/P4,QD75D1/D2/D4, A171SH,A172SH,A173UH,A273UH]

- Application examples [Conveyor, carrier unit, roller feed, crane, etc.]

Y axis

Speed

Passing point

Start point

Radius

Passing point

Speed change in X axis

Time

End point

X axis

< Constant speed control >

- From the start point which is the current stop address, positioning control is performed to the end point address at an equal speed by way of passing points.

- Passing points make small circular arc.

- Applicable models [AD75P1/P2/P3,AD75M1/M2/M3, QD75P1/P2/P3,QD75D1/D2/D4, A171SH,A172SH,A273UH]

- Application examples [Steel sheet fusing, welder, applicator, crane, transfer robot, etc.]

Time

4-4

Positioning Control Advanced Positioning 4

Y axis

Speed

Change

point

Start point

Speed change in X axis

Changed end point

Original end point

X axis

Time

< Position follow-up control >

- If the end point address is changed while a positioning control movement is being executed, positioning is controlled to the new end point address.

- Applicable models [A171SH,A172SH,A273UH]

- Application examples [Product follow-up type, application line and welding line]

X axis

Speed

Z axis

Start point

Speed change in the Y axis

Time

End point

Y axis

< Three-dimensional interpolation control >

- From the start point which is the current stop address, 3-axis linear interpolation control and 3-axis circular interpolation control are performed to the end point address by way of passing points.

- Applicable models [A171SH,A172SH,A273UH]

- Application examples [Assembly robot, welding robot, application robot and transfer robot]

4-5

Positioning Control Advanced Positioning 4

4-6

Positioning Control Actual Positioning 5

1 The Wor l d of Positioning Control

2 Positioning by AC Servo Sys tem

3 Components of Positioning Control and Their Roles

4 Advanced Positioning

5 Actual Positioning

6 Product Line up

A Appendix A: Tentative Selection of Motor Capacity

Positioning Control

5. Actual Positioning

Terms required for positioning control have been explained in the first three sections. In this section, let’s experience actual positioning control based on the knowledge you have learned so far.

The position controller FX can also be used in place of the FX

5.1 Demonstration Equipment

Two different levels of demonstration equipment can be u sed for this example, depend ing on what is available. The basic set utilizes the live monitoring function of the FX-PCS-VPS software, where as, the more comprehensive set makes use of an X Y plotting table, to actually see the axes move, and draw the resulting locus.

5.1.1 Basic Set

The demonstration items required for the basic set up are as follows;

-20GM F2-422 CAB0 Communications cable FX-232AW(C) Converter FX-232 CAB-1 Communications cable Personal computer FX-PCS-VPS\Win software

-20GM is used for the demonstration as show below. An FX-20GM

-20GM.

Actual Positioning 5

MITSUBISHI

AUTO

POWER

MELSECFX2N-10GM

READY

START

ERROR

STOP

CPU-E

ZRN

SVRDY

FWD

SVEND

MANU

RVS

PGO

DOG

LSF

LSR

CLR X0 X1 X2 X3 Y0 Y1 Y2 Y3 Y4 Y5

PLC EXT

I/O MOTOR

5.1.2 Comprehensive Set

The demonstration items required for the comprehensive setup are as follows;

-20GM F2-422 CAB0 Communications cable FX-232AW(C) Converter FX-232 CAB-1 Communications cable Personal computer FX-PCS-VPS\Win software Plotter Communications cable (*1 Specific to plotter) X Y Plotting table

MITSUBISHI

AUTO

POWER

MELSECFX2N-10GM

READY

START

ERROR

STOP

CPU-E

ZRN

SVRDY

FWD

SVEND

MANU

RVS

PGO

DOG

LSF

LSR

CLR X0 X1 X2 X3 Y0 Y1 Y2 Y3 Y4 Y5

PLC EXT

I/O MOTOR

FX-422CAB0 F2-232CAB-1FX-232AW(C)

Plotter

FX-422CAB0

F2-232CAB-1FX-232AW(C) Cable *1

5-1

Positioning Control Actual Positioning 5

5.2 Operation of the demonstration equipment

Source the required demonstration equipment, and setup as in section 5.1. If a plotter is being used refer to the operations manual for the particular unit and setup accordingly.

Throughout this example it is assumed that you will have read and understood both the FX 20GM Hardware / Programm ing manual (JY992D77801) and the FX-P CS-VPS/Win-E softtware manual (JY992D86801) or you will have then close at hand for reference.

For this example we will use the basic setup of Personal computer and FX Let’s draw the locus shown below dr iven by the X and Y axes simult aneously. The output Y0 is

added to imitate a pen, or other end effector.

-20GM.

Start point

End Point

A: Start point, this point can be anywhere. B: (0,0), Zero point, wait for 2 seconds. C: (80,100), Output Y0 turns ON, wait for 2 seconds. D: (110,200). E: (200,200).

F: (200,100). G: (150,100), Output Y0 turns OFF, wait for 2 seconds. H: (150,70), End point.

A to B - Return to Electrical Zero. B to C - High speed positioning. C to D - Linear interpolation. D to E - High speed positioning. E to F - Clockwise circular interpolati on. F to G - High speed positioning. G to H - High speed positioning.

5-2

Positioning Control Actual Positioning 5

5.2.1 Program example

The program below demonstrates basic positioning using the FX

-20GM. As this program is designed to be used without a mechanical plotter, the electrical zero point is used for reference.

Many programs can be stored in a GM unit at one time. This example uses program number 0.

This command is to move from the start point, to the electrical zero point

Here the program waits for 2 seconds, using a 10ms timer.

This command indicates the rapid command to position C.

Here Y0 is turned on, to mimic the use of an end effector tool.

This timer allows a tool to be activate d, or an operation executed.

This command is the start of a continuous steady path, first using linear interpolation to position D

To position E, only the X axis need move.

For a smooth arc, circular interpolation is use d. This example shows the start and end positions (F), as well as the radius and a speed f.

To position G, only the X axis need move.

Here Y0 is turned off, to mimic the the end of the end effector use.

Again a timer related to the operation above.

This command rapidly moves only the Y axis a short distance to position H.

The end of the program, and a wait for the next start command.

5-3

Positioning Control Actual Positioning 5

5.2.2 Writing the program

Using FX-PCS-VPS\Win-E, re-create the flow chart program shown in section 5.2.1. If assistance is required in the operation of the software, please refer to the Software manual JY992D86801.

When opening a new file in VPS, choose ‘FX(2N)/E-20GM with simultaneous 2 axis’

The example program is designed to utilize the real time monitor function of VPS software. If a mechanical plotter is being used substitute the ‘DRV Ret’ command for a ‘DRVZ’, return to origin command. Be sure to set up the plotter in accordance with the instructions and guidelines applicable to and supp lied with your specific plotter.

Along with the Flow chart, create a monitoring window similar to the one shown below.

All of the items on the monitoring window can be found under the insert tab on the main menu at the top of the screen.

Items inserted include: Current Position

Plotting (double click on plot area to change the scale) Device Status (Y0) Manual Operation (Start, Stop, Jog -, Jog +, for both X and Y axes, each inserted separately) FX-GM Status

Plus, a rectangle from the drawing tool bar, to highlight the Y0 indicator .

5-4

Positioning Control Actual Positioning 5

5.2.3 Parameters

In addition to the preparation of a positioning program, diversified parameters should be set in the FX

-20GM. In this example, only a few parameters need be set. If a plotting table is used, the parameters should be set in accordance with its mechanism. The se will depend upon the spe cific plotter type, and should be found in the documentation provided with the plotter.

Below are the four positioning parameter w indows from VPS, cop y these settings into your program.

The values for both the X and Y axes are the same for all parameters.

The system of units we will be using is both mechanical and motor, so that the position can be controlled in mm, deg, 1/10 inch etc. while the speed can be controlled by the number o f pulses. The system units should be set to ‘mm, and all other options left as default.

So that we can follow the path created by the FX2N-20GM, the Max speed should be set quit e low. Intern both the JOG speed and the Interpolation value must be reduced. In practice, it is impossible to have the JOG speed faster than the Max speed setting.

Remember to change the setting for the Y axis also.

5-5

Positioning Control Actual Positioning 5

As we will not be connecting any mechanical hardware to the FX2N-20GM, the li mit switch and DOG switch settings do not require setting. We do how ever need to reduce the Creep speed and the Zero return speed.

All of the parameter settings o n this screen window can be left as their def ault values, they are already optimized for our program.

If a plotter table is be ing used, all o f the above p arameters will need to be checke d before power ON, or operation.

5-6

Positioning Control Actual Positioning 5

5.2.4 Operation

Now that your program has been written, check the communication cables between the FX 20GM and PC, then download your program to the FX

-20GM. Make sure that the GM unit is

in ‘MANU’ mode before download, or it will be impossible to communicate. In VPS, start the Monitor mode by clicking the Monitor icon on the tool bar, shown below.

Monitor icon

The Monitor mode screen will appear. Here, the flow icon menu and program map have been removed. Three windows are displayed;

Monitoring window: This is the window you c reated, and will use to cont rol t he FX

-20GM and

view the resulting locus. Sub-task - Monitor mode: This window in not needed as we do not use any sub rout ines in our

programs, it can be minimized to create more space on the screen. X-axis and Y-axis - Monitor mode - At first this window will be empty, but as soon as you start

your program, the flow chart will appear, and scroll through, keeping the live instruction highlighted in red.

After minimizing the Sub-task monitor window, resize the Monitoring window and then the Xaxis and Y-axis window.

Now you are ready to begin. Firstly set the start point, thi s can be done be either using the X and Y axis JOG buttons, or by

double clicking on the current position display. Double clicking the current position display brings

up this window; For X, replace 0 with 50, and click on the ‘Write to

FX-GM’ button. For Y, replace 0 with 125, and click on the ‘Write to

FX-GM’ button. As you write that data to the GM, you will see a

red line being draw n on th e plot in the M onitoring window. This shows the current position.

We want a clean plot area to begi n with , so double click on the plotting area, and click on the clear button.

5-7

Positioning Control Actual Positioning 5

The next step, it to switch the FX2N-20GM to ‘AUTO’ mode, so that the program can be executed.

Finally, on the Monitor screen click on either the X or Y axis start buttons. It does not matter which one, as both will start the program. Sit back and see what you have produced.

Your screen should look similar to the one shown below, the plot should be identical.

To run the program again, set a new start position (or let it start from where it is), clean the plot area, and press start.

If your plot does not look the same as the one above, check yo ur program against the one in section 5.2.1.

If it does, now is the time to experiment some more. Try a new program, perhaps include subtasks and multiple flow charts . Only a sample of the functionality available in VPS has be used in this example program, try using some of the other programming aspects.

5-8

Positioning Control Product Line up 6

1 The Wor l d of Positioning Control

2 Positioning by AC Servo Sys tem

3 Components of Positioning Control and Their Roles

4 Advanced Positioning

5 Actual Positioning

6 Product Line up

A Appendix A: Tentative Selection of Motor Capacity

Positioning Control

6. Product Line up

We are offering diversified position controllers, servo amplifiers and servo motors. You can select desired units in accordance with your system and application. For the derails, refer to the catalog of each product.

6.1 Position controller

1) Outline of position controller models

In the position controller, the positioning function is built in or extended. For some position controllers, an PLC executes positioning programs. Other position contro llers execute programs using their unique positioning language without regard to any PLC.

Product Line up 6

FX Series

A Series

Q Series

Model name/unit

name

/FX1N Series

FX PLC

1-axis position controller FX-10GM

-10GM

2-axis position controller FX-20GM

-20GM

2-axis position controller E-20GM

1-axis pulse output block FX

1- to 3-axis position controller AD75P1 to AD75P3

1- to 3-axis position controller AD75M1 to AD75M3

1- to 4-axis position controller QD75P1 to QD75P4

1- to 4-axis position controller QD75D1 to QD75D4

-1PG

Positioning

language

FX sequence

language

Dedicated

language

FX sequence

language

A sequence

language

Positioning

data

Q sequence

language

Positioning

data

Outline

Pulse output type for independent 2 axes Through application instructions in the PLC main unit, absolute position detection, return to mechanical zero point and one-speed constant positioning are available.

Pulse output type for 1 axis

Pulse output type for 2 axes Independent 2 axes or simultaneous 2 axes (linear interpolation, circular interpolation)

Pulse output block for FX Used as an extension block

Pulse output type for 1 to 3 axes Simultaneous 1 to 3 axes, independent 1 to 3 axes, 2axis linear interpolation, 2-axis circular interpolation

SSC net connection type for 1 to 3 axes Simultaneous 1 to 3 axes, independent 1 to 3 axes, 2axis linear interpolation, 2-axis circular interpolation

Pulse output type for 1 to 4 axes (open collector output) Simultaneous 1 to 4 axes, independent 1 to 4 axes, 2 to 4-axis linear interpolation, 2-axis circular interpolation

Pulse output type for 1 to 4 axes (differential output) Simultaneous 1 to 4 axes, independent 1 to 4 axes, 2 to 4-axis linear interpolation, 2-axis circular interpolation

Easy sequence function is provided. Bus connection to FX Series PLC is available. (Position controller can be used independently also. )

Easy sequence function is provided. (Position controller can be used independently also. )

Series PLC

6-1

Positioning Control Product Line up 6

Motion

controller

Model name/

unit name

A171SH A172SH A173SH

A273UH

Positioning language Outline

Language dedicated to servo system [4-, 32-axis independent control, 2- to 4axis linear interpolation control, 2-axis circular interpolation control, speed control, equal speed control, position follow-up control]

NC language [Control using G codes]

Dedicated robot [Three-dimensional linear/circular interpolation control]

Mechanical support language [Synchronous operation control]

A171UHCPU (512 I/O points): 4-axis control A172SHCPU (512 I/O points): 8-axis control A173UHCPU (2,048 I/O points): 32-axis control

Servo amplifier (0.05 to 55 kw are dedicated to SSC net connection.)

A3UCPU (2,048 I/O points): 32-axis control

Servo amplifier (0.05 to 0.6 kw allow built-in type also.) (0.05 to 55 kw are dedicated to SSC net connection.)

Mechanical support language in motion controller

A new world of synchronous mechanism is open.

Programming in virtual world By simply connecting and laying out a

transmission module and an output module to a virtual main shaft on the screen, while regarding diversified synchronous mechanism as software mechanical modules, you can easily program a synchronous system.

6-2

Positioning Control Product Line up 6

1) When and which position controller?

In addition to the PLC series, take into account the following contents to determine the position controller to be used.

a) Determine the position controller to be used in accordance with the number of controlled

axes (motors).

1-axis control

2-axis control

3-axis control

Control of 4-

axes or more

Position controller dedicated to 1 axis

FX-10GM, FX

-10GM, FX2N-1PG

AD75P1, AD75M1, QD75P1, QD75D1

Only 1 axis of 2-axis position controller

FX-20GM, E-20GM, FX

-20GM, FX1S/FX1N Series PLC

AD75P2, AD75M2, QD75P2, QD75D2

2-axis position controller

FX-20GM, E-20GM, FX

-20GM, FX1S/FX1N Series PLC

AD75P2, AD75M2, QD75P2, QD75D2

3-axis position controller

AD75P3, AD75M3

Combination of 1-axis position controller and 2-axis position controller

For 1-axis control, for 2-axis control

4-axis position controller

QD75P4, QD75D4, A171SH

Position controller for 4 axes or more

A171SH, A172SH, A173UH, A273UH -----

Combination of 1-axis position controller, 2-axis position controller and 3-axis position controller

for 1-axis control, for 2-axis control, for 3-axis control

6-3

Positioning Control Product Line up 6

b) Determine the position controller to be used in accordance with the output pulse

frequency. However, the pulse frequency actually used inside the servo amplifier can be increased by electronic gearing.

100kp/sec

200kp/sec

When the required command pulse is 100 kpps or less

-1PG, FX1S/FX1N Series PLC

When the required command pulse is 200 kpps or less

FX-10GM, FX-20GM, E-20GM, FX2N-10GM, FX2N-20GM

400kp/sec

1Mkp/sec

AD75P

When the required command pulse is 400 kpps or less

AD75P

When the required command pulse is 1 Mpps or less

AD75M

, QD75P



, QD75P



, A171SH, A172SH, A173UH, A273UH



c) Determine the position controller to be used in accordance with handli ng of the feedback

pulse.

Position

controller

Command

pulse

To servo amplifier

Servo

amplifier

Servo

motor

The position controller only outputs pulses, and does not check feedback pulses. Accordingly, it is not confirmed whether or not rotation in accordance with command pulses is actually performed.

Position

controller

SSC net

Feedback

pulse

PLG

Encoder

To position controller

Servo

motor

Servo

amplifier

Feedback

pulse

PLG

Encoder

FX-10GM, FX-20GM, FX E-20GM, FX

/FX1N Series PLC

FX AD75P

-10GM, FX2N-20GM,

, QD75P, QD75D



-1PG,



The position controller checks feedback pulses. Accordingly, it is confirmed whether or not rotation in accordance with command pulses is actually performed.

AD75M

, A171SH A172SH,



A173UH, A273UH

6-4

Positioning Control Product Line up 6

6.2 Servo amplifier

1) Outline of serve amplifier models

Model name Outline

• DC 24V

• Size is extremely small, and capacity is small.

MR-J2-Jr Series

MR-C Series

MR-J2/J2S Series

MR-H Series

MR-H-ACN Series

• Applicable to 10 to 30 w.

• Used for semiconductor manufacturing unit and small robots.

• Setup so ftware by per s ona l com pute r is availab le.

• General-purpose type optimal to use instead of stepping motor (dedicated to position control).

• Size is extremely small.

• Applicable to 30 to 400 w.

• Real-time auto tuning eliminates adjustment in setup.

• Inertia is extremely low.

• Speed can increase at constant torque without step out until high speed area, and operation is smooth even at low speed.

• Setup so ftware by per s ona l com pute r is avai lab le.

• General-purpose type in compact body easy to use.

• Applicable to 50 w to 7 kw. 100 VAC input type is offered as a series.

• Real-time auto tuning eliminates adjustment in setup.

• Convenient test run function and diagnosis function are provided.

• Applicable to low noise operation.

• Setup so ftware by per s ona l com pute r is avai lab le.

• General-purpose type of high performance and high response.

• Applicable to 50 w to 55 kw.

• Real-time auto tuning eliminates adjustment in setup.

• Applicable to low noise operation.

• Interactive parameters facilitate maintenance.

• Setup so ftware by per s ona l com pute r is avai lab le.

• 1-axis positioning function is built in.

• Applicable to 50 w to 55 kw.

• Frequent operation of high precision is available.

• Real-time auto tuning eliminates adjustment in setup.

• Applicable to low noise operation, absolute value and diversified ways of return to zero point.

6-5

Positioning Control Product Line up 6

2) When and which servo amplifier? In addition to the series, take into account the following contents to determine the servo amplifier to be used.

a) Determine the servo amplifier to be used in accordance with the ra ted output of the servo

motor.

400w or less

7kw or less

55kw or less

Extremely small capacity type servo amplifier

MR-J2-Jr, MR-C

Small capacity type servo amplifier

MR-J2



Medium or large capacity type servo amplifier

MR-H-



b) Determine the servo amplifier to be used in accordance with the servo motor model.

When the servo motor is determined in accordance with the purpose of use, the rated torque and the inertia moment, select a connec table servo amplifier while taking into account the responsibility and the extensibility.

6-6

Positioning Control Product Line up 6

6.3 Servo motor

Servo motors are classified into series in accordance with the application, the outside dimensions and the motor inertia moment. In each series, models of different output capacity are lined up.

Motor model

name

(encoder

resolution)

HC-AQ (8192P/rev)

HC-PQ (4000P/rev)

HC-KF (8192P/rev) HC-KFS (131072P/rev)

HC-MF (8192P/rev) HC-MFS (131072P/rev)

HA-FF (8192P/rev)

HC-SF (16384P/rev) HC-SFS (131072P/rev)

Rated

rotation

speed

(r/min.)

3000 10W to 30W

3000 30W to 400W

3000 50W to 400W

3000 50W to 750W

3000 50W to 600W

3000 500W to 3.5kW

2000 500W to 7kW

1000 850W to 3kW

Rated

output

capacity

Features Application

Extremely small size, small capacity and 24 VDC specification (compatible with speed reducer). Optimal to application for small capacity using servo amplifier MR-J2-JR.

Extremely low inertia and small capacity (compatible with speed reducer). Optimal to use instead of stepping motor.

Low inertia and small capacity (compatible with speed reducer). Optimal to machine with load inertia moment fluctuation and machine of low rigidity such as belt drive type because motor inertia moment is large.

Extremely small inertia and small capacity (compatible with speed reducer). Optimal to frequent operation directly connected to ball screw because motor inertia moment is small.

Small inertia and small capacity (compatible with speed reducer). Applicable to wide range of applications because control is stable from low speed to high speed.

For high speed

For speed reducer (compatible with speed reducer)

For high torque

Medium inertia and medium capacity. Selectable in accordance with motor rated rotation speed from low speed to high speed.

• Small sl ider

• Small ac tuato r

•Cylinder

• Ext re mely small robot

• Tip of robot

• In-circuit tester

• Belt drive, robot

• Mounter, sawing machine

• X-Y table, food machine

• Inserter, mounter, bonder

• Drilling unit for PCB

• Label printer, knitting machine

• Ext re mely small robot

• LCD/wafer carrier unit

• Food machine, printer

• Small ro bot, X-Y table

• Winder, tension unit

• Carrier unit, dedicated machine

• Robot, testing machine

• X-Y table, turret

• Loader, unloader

• Winder, tension unit

6-7

Positioning Control Product Line up 6

Motor model

name

(encoder

resolution)

HC-RF (16384P/rev) HC-RFS (131072P/rev)

HC-UF (16384P/rev) HC-UFS (131072P/rev)

HA-LH (16384P/rev)

HA-LF (16384P/rev)

Rated

rotation

speed

(r/min.)

3000 1kW to 5kW

3000 100W to 750W

2000 750W to 5kW

2000 11kW to 22kW

2000 30kW to 55kW

Rated

output

capacity

Features Application

Low inertia and medium capacity (compatible with speed reducer). Optimal to frequent operation directly connected to ball screw because motor inertia moment is low .

Small capacity

Medium capacity

Low inertia and large capacity. Suitable to frequent positioning because motor inertia is low.

Large capacity and 400 V AC specification. Suitable to positioning requiring large force because motor capacity is large.

Flat type Optimal to application in which mounting is restricted.

• Frequent carrier unit

• Roll feeder

• Loader, unloader

• Robot

• Food processor

• Carrier unit

• Winder, tension unit

• Press feeder, injection molding unit

• Semiconductor manufacturing unit, carrier line

• Press transfer unit

• Lifter, automatic warehouse

• Injecti on molding unit

• Semic ondu ctor manufacturing unit

• Large carrier unit

*3 The model name "HC-S" is compatible with the servo amplifier MR-J2S.

6-8

Positioning Control Tentative Selection of Motor Capacity A

1 The Wor l d of Positioning Control

2 Positioning by AC Servo Sys tem

3 Components of Positioning Control and Their Roles

4 Advanced Positioning

5 Actual Positioning

6 Product Line up

A Appendix A: Tentative Selection of Motor Capacity

Positioning Control

Appendix A:

A-1: Tentative Selection of Motor Capacity

Temporarily select the motor capacity at fir st while taking into account the following two points, and determine the model.

• The rated torque of the motor should be larger than the effective torque.

• The load inertia moment shoul d not ex ceed ap proximate ly 10 times of the in ert ia momen t of the motor itself.

A-1

Positioning Control

A-1-1: Motor effective torque

When the motor effective torque obtained by the calculation below does not exceed the rated torque (100%) of the servo motor specifications, it is suitable.

If the obtained effective torque exceeds 100%, increase the motor capacity and perform the calculation again.

Effective torque

(Trms)

(Torque during acceleration)2 × Acceleration time +

(Torque during constant speed)

(Torque during deceleration)2 × Deceleration time

Cycle time (including rest time)

× Constant speed time

In the effective torque calculation equation, the torque during acceleration, constant speed, deceleration, the cycle time and the machine load are as follows.

1) The torque during acceleration is the torque required to reach the constant speed after startup and acceleration.

Torque during acceleration = Torque to accelerate load inertia moment + Load torque

(TL)(Ta)(TMa)

A-2

Positioning Control

2) The torque during constant speed is the torque required to move the load at the constant speed.

Motor torque during constant speed = Load torque

3) The torque during deceleration is the torque required for deceleration and stop.

Torque during deceleration = Torque to decelerate load inertia moment + Load torque

(TL)(TML)

(TL)(-Ta)(TMD)

4) How to obtain the cycle time The representative machine operation pattern consists of acceleration, constant speed, deceleration and rest. The cycle time indicates the total time required for these actions.

A-3

Positioning Control

5) Machine load torque (TL) The rotation force required to move or cut an object is called load torque. During operation at constant speed, the motor is outputting the torque balancing this load torque.

• The calculation equation to obtain the load torque varies depending on the motion type (horizontal, rotation or vertical).

• In the case of rotation, the load torque is calculated based on the product of the rolling resistance coefficient o f the bearing (ba ll beari ng, for example ) and the load applie d in the radius direction of the bearing.

A-1-2: Load inertia moment

Difficulty to move a stationary object or difficulty to stop a moving object is called inertia moment. As the inertia moment is larger, the load is more difficult to move and stop. In the servo motor, the inertia moment gives considerable effect especially at the time of start and stop. Accordingly, calculate the load inertia moment, then select a servo motor so that the obtained load inertia moment does not exceed 10 times of the inertia moment of the se rvo motor itself.

Start

The motor starts to move an object while overcoming the inertia moment.

Operation at constant speed

The inertia moment gives no effect.

Stop (deceleration



stop)



The motor stops an object while overcoming the inertia moment.

A-4

Under no circumstances will Mitsubishi Electric be liable or responsible for any consequential damage that may arise as a result of the installation, use and/or programming of the products associated with this manual. All examples and diagrams shown in this manual are intended as an aid to understanding the text, n ot to guarantee operation. Mitsubish i Electric will accept no responsibility fo r actual use of the product based on t hese illustrative examples. Owing to the very great variety of possible applications, users must satisfy themselves as to the suitability of each specific application.

JY992D89901A (MEE0007)

HEAD OFFICE: MITSUBISHI DENKI BLDG MARUNOUCHI TOKYO 100-8310 TELEX: J24532 CABLE MELCO TOKYO HIMEJI WORKS: 840, CHIYODA CHO, HIMEJI, JAPAN

Effective July. 2000 Specifications are subject to change without notice.

Mitsubishi Electronics A173SH, A172SH, A171SH User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

Cautions on Safety

Introduction

1 The World of Positioning Control

1.1 Welcome to the new world!

1.2 Diversified actuators

1.3 Positioning method type

2 Positioning by AC Servo System

2.1 When an AC servo system is introduced

2.2 Examples of AC servo systems

3 Components of Positioning Control and Their Roles

3.1 Positioning controller

3.1.1 Command pulse and feed quantity

3.1.2 Command pulse and feed speed

3.1.3 Setting the acceleration/decelerat ion time

3.1.4 Backlash correction functio n

3.1.5 Zero point return function

3.2 Servo amplifier and servo motor

3.2.1 Positioning control in accordance with command pulse

3.2.2 Deviation counter function

3.2.3 Servo lock function

3.2.4 Regenerative brake function

3.2.5 Dynamic brake function

3.3 Drive mechanism

3.3.1 Concept of drive system movement quantity

3.3.2 Setting the target position

4 Advanced Positioning

4.1 Interpolation control

4.2 Other controls

5 Actual Positioning

5.1 Demonstration Equipment

5.1.1 Basic Set

5.1.2 Comprehensive Set

5.2 Operation of the demonstration equipment

5.2.1 Program example

5.2.2 Writing the program

5.2.3 Parameters

5.2.4 Operation

6 Product Line up

6.1 Position controller

6.2 Servo amplifier

6.3 Servo motor

A-1: Tentative Selection of Motor Capacity

A-1-1: Motor effective torque

A-1-2: Load inertia moment