Mirror Assembly Controller Based on

S7-200 PLC

Qiang-qiang RONG1 Jin-hua DING

1 Xiao-jing LEI

1 Yu-jun HU

1

Wei-fu WANG1 Wen-jing LI

1

1Dalian Polytechnic University, Dalian, China

Abstract

Aimed at features of mirror assembly

process, a mirror assembly controller

with servo motor as actuators was

developed, based on S7-200 PLC and

position control module EM253.

According to the working principle of

mirror assembly, the mirror positioning,

mirror frame orientation and manipulator

working process were described. This

control system realized precise position

control of the manipulator and the

location error could be reached 30μm.

The hardware and software of the mirror

assembly controller was also discussed.

Keywords: Mirror assembly; S7-200

PLC; Servo motor; EM253

1. Introduction

Mirror assembly is one of the processes

in furniture production line. This process

involves mirror frame orientation, mirror

positioning, mirror suction, mirror

moving, blowing, etc. The key

technology is how to ensure positioning

accuracy of the picture frame and the

manipulator. Position precision of the

manipulator mainly depends on the

motion controller and the servo driver.

High-end control module can realize

complicated motion, but the cost is high

and the structure is complicated[1]

.

Mirror assembly process need accurate

position control, but its trajectory is not

complex, so there is no need to choose

the expensive high-end motion control

system. Therefore a simple and reliable

servo control system is developed, using

Siemens S7-200 programmable controller

and EM253 position control module,

realizing control of the high precision

motion of the manipulator.

2. Structure of the Mirror Assembly

System

As figure 1 shows, mirror assembly

system is composed of three parts: mirror

positioning device, mirror frame

positioning device and mirror moving

manipulator device.

Fig. 1: Structure of the mirror automatic

assembly system.

Mirror position fixing device includes

mirror conveyor belt, mirror locating

piece and clamping cylinder, as shown in

International Conference on Information, Business and Education Technology (ICIBIT 2013)

© 2013. The authors - Published by Atlantis Press 204

figure 1. Mirror is conveyed by the

conveyor belt, it should be stopped when

meeting locking block 1. At this moment,

there is a deviation δ 1 (as shown in figure

3) between mirror and locking block.

When clamping cylinder complete its

firstly positioning, the clearance δ 1 is

eliminated, but a new deviation δ2 (as

shown in figure 4) will be produced.

Restart belt motor again (the running time

is 1s). After motor stops, the clamping

cylinder should make its secondary

positioning, then the mirror is absolutely

located. Structure of the mirror position

fixing devices is shown in figure 2.

Mirror

Transport

Direction

Mirror

Locking

Block 2

Locking Block 1

Mirror

Clamping

Cylinder

Fig. 2: Structure of the mirror position fixing

device.

Deviation

δ1

Fig. 3: Deviation δ1 of the mirror position

fixing.

Deviationδ2

Fig. 4: Deviation δ2 of the mirror position

fixing.

Position fixing device of the mirror

frame is made up by mirror frame

delivery motor, clamping cylinders,

fastening cylinder and locating piece.

Position fixing principle of the frame is

the same as the mirror’s. After mirror

frame is fully positioned, fastening

cylinder will press the frame and make it

in its right position.

Mirror moving manipulator device is

consist of X axis servo motor, Y axis

servo motor (brake motor), suction cup,

screws, guide rails, etc. Servo motor

controls position of the suction cups,

realizing operations as glass suction,

moving, holding and releasing. The size

of the mirror frame is 400mm×1600mm

and the mirror size is 398mm×1598mm,

so the maximum allowable assembly

deviation is 0.5mm at each side, which

puts forward a strict requirement of the

manipulator precision.

3. Hardware Design of the Control

System

3.1. Hardware Configuration of the

System

Mirror assembly control system consists

of PC (touch screen), lower machine

(Siemens S7-200 series PLC CPU226),

position control module (EM253), ac

servo motor and servo driver (ADSM-

S110-060M-ac servo motor), encoder, etc.

Figure 5 shows principle structure of the

control system.

Touch

ScreenPLC

EM253

Servo

driver

P0

direction

enabled

clear

Servo

Motor

coding

movement of X axis or Y axis

Nearly

limit

Reference

points

Far

limit

LIM-

REF

LIM+

monitoring

control

control

control

P1

DIS

CLR

LIM-

REF

LIM+

pulse

Fig. 5: Principle structure of the control

system.

205

Upper computer uses Siemens

smart1000 touch screen, and it makes

communication with PLC through serial

port (RS485). Upper machine sets

movement parameters, realizing position

control of the manipulator, monitoring

working condition of the executive parts,

variable register, etc.

3.2. Position Control Module EM253

Position control module EM253 controls

position and speed of the moving

manipulator. It is a special function

module of S7-200 PLC. It communicates

with PLC through I/O port bus, producing

pulse for servo motor [2]

. Figure 6 shows

the connection way between EM253

module and servo motor driver. EM253

belongs to open loop control mode, so it

can’t feedback real state of the

manipulator well[3]

. Using servo driver’s

differential output signal and the encoder

feedback signal, closed loop control can

be realized by setting proper parameters

of the servo driver.

AC220/230

Single-phase

or Three-phase

50/60HZ

N+

N-

P+

P-

T_REF

12V GND

+24V

COM

DI1

DI2

DI3

DI4

DI5

DI6

DI7

DI8

DO1+

DO1-

DO2+

D02-

DO3+

D03-

D04+

D04-

D05+

D05-

32

33

34

35

41

25/26/27

42/43/44

28/29/30

16

1

17

2

18

30

19

4

24

9

23

8

22

7

21

6

20

40

24V

SVON

CNTCLR

CWSTE

TC0

ALMRST

24V

1.5K

1.5K

1.5K

1.5K

1.5K

RDY

ZS

HOME

POSIN

ALM

RB2RB1RB

R

STL1

L2

RED

WHITE

BLACK

GREEN

U

V

W

FG

A+

A-

B+

B-

Z+

Z-

U+

U-

V+

V-

7

8

9

10

15

5

4

3

2

1

W-

GND

13

11/12

6 W+

M1

GND

M2

37

25/26/27

36

OA+

OA-

OB+

OB-

OZ+

OZ-

10

11

12

13

14

15

CN1

CN1

CN1

CN1

CN2

CN1

Servo

Motor

Encoder

1.5K

1.5K

A Phase Pulse

EM253

Position

Control

Module

Brake resistance

Servo

Driver

B Phase Pulse

C Phase Pulse

Fig. 6: The connection way between EM253

module and servo motor driver.

4. Software Design of the System

4.1. Main program design

Control system uses point control mode

and modular design thought. PLC control

program is divided into four parts:

system startup subroutine

initialization subroutine

servo motor subroutine

mirror frame orientation and mirror

positioning subroutine

4.2. Functions of the Subroutine

System startup subroutine controls state

of the whole system through gathering

external start and stop signal, using the

typical start, keep and stop control circuit

to achieve.

Initialization subroutine triggers the

register SM0.1 or SM0.0 to achieve servo

motor initialization operation[4-5]

, establishes system zero point coordinates,

assigns an initial value for registers

through the MOV instruction.

Servo motor subroutine controls

EM253 module to output a certain

number of pulse and frequency[6]

, using

commands as POSx_GOTO and

POSx_RUN, realizing single speed

positioning operation of the manipulator.

Figure 7 introduces software process of

the servo motor subroutine.

Servo Initialization

X Axis to the Taking Position

Y Axis to the Holding Position

Is Mirror

Positioning Ok?

Y Axis to the Taking Position

then Sucking the Mirror

X Axis to the Putting Position

Y Axis to the Putting Position

then Releasing

Y Axis to the Holding Position

Y

Y

Y

Y

Y

N

N

N

N

N

Reach the Low Pressure?

Is Y Axis in the

Holding Position?

Is Frame

Positioning Ok?

Reach the High Pressure?

Y Axis to the Holding Position

Fig. 7: Software process of the servo motor

subroutine.

206

Mirror frame orientation and mirror

positioning subroutine completes

transport and positioning work of the

picture frame and mirror through

controlling belt machine and the action of

the related cylinder

5. Results

Graph of the mirror moving manipulator

position error is shown in figure 8. After

pilot production of the system, it has been

formally used in production. Through

statistics and analysis maximum position

error of the manipulator in a particular

situation that the manipulator executives

1000 times strokemm in full load cases

and respectively in different speed ，we

could draw a conclusion that this system

can realize precise localization of the

manipulator. Actual measurement shows

that the X axis biggest position error is

30μm and the Y axis biggest position

error is 28μm. It can meet the mirror

assembly accuracy.

0 50 100 150 200 250 300 350 4000

5

10

15

20

25

30

Ma

xim

um

Po

sit

ion

Erro

r o

f X

Ax

is(u

m)

X Axis Speed(mm/s) 0 50 100 150 200 250 300 350 400 450 500 550

0

5

10

15

20

25

30

Ma

xim

um

Po

sit

ion

Erro

r o

f Y

Ax

is(u

m)

Y Axis Speed(mm/s)

Fig. 8: Graph of the maximum position error

of the Manipulator

6. Conclusion

Using Siemens S7-200 PLC and position

control module EM253, making full use

of advantages of the control module in

high precision motion control aspects, the

mirror automatic assembly control system

is developed. The circuit composition is

simple and convenient, and it is easy to

install and debug. The system can realize

accurate position control and it can be

applied to other position control

occasions, to achieve production

automation.

7. References

[1] Hu Jiali, Yan Baorui, Zhang Anzhen.

Application of S7-200 PLC in

Position Control of Servo Motor[J].

Process Automation Instrumentation,

pp. 38-40, 2009(30).

[2] Xu Lumei, Zheng Guohjua, Li Ping.

The Design of Welding Torch

Swinging Control System Based on

CPU224XP[J]. Applied Energy

Technology, pp. 45-47, 2009(1).

[3] Lin Song. Application of the Siemens

Control Module in Assembly

System[J]. Science & Technology

Information, pp. 324-325, 2006(9).

[4] Gao Anbang, Tian Min, Yu Ning.

Siemens S7-200 PLC Application

Design[M]. Bei Jing: China Machine

Press, pp. 247-250, 2011.

[5] S7-200 PLC User Manual. 2004.

[6] Tao Xian, Yang Zesheng. PLC-

basede Control System X-Y Table

Design[J]. Development & Innovation

of Machinery & Electrical Products,

pp. 131-132, 2012(25).

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