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Control System for Experimental Model of Electric Elevator

Article · April 2015

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Mohammed Moanes Ezzaldean Ali Mustafa S. Bakr

University of Technology, Iraq University of Oxford
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 Journalof Name,
Journal Control, Vol. 1, and Mechatronic Systems, Vol. 1 (1), 22-26, Mar. 2015
Robotics,
ISSN: Pending, DOI: Pending, Published online: www.unitedscholars.net/jcrms-archive

Control System for Experimental Model of Electric

Elevator
Mohammed M. Ezzaldean, Mustafa S. Bakr
(University of Technology), Department of Electrical Engineering, Baghdad, Iraq / email:
dr.mohammed.moanes@uotechnology.edu.iq

ABSTRACT
early 1950s brought the earliest predictive systems
Modern elevator systems work under control of digital which could anticipate traffic patterns within a
system such as a Programmable Logic Controller (PLC) building to deploy elevator movement in the most
or a single chip computer. A proposed control system for efficient manner. Relay-controlled elevator systems
an experimental model elevator is suggested and remained common until the 1990s during which
developed. This system consists of a PC and a data they were gradually replaced with solid-state based
acquisition system. The system's functions are managed controls, which are now the industry standard [1-3].
by a visual basic program. The design used in this
program is formed in a manner that makes the elevator Modern elevator systems work under control of
suitable for educational and laboratorial purposes. The digital system like PLC or single chip computers.
operation of the control system is tested and all the This paper describes the procedure of upgrading a
elevator operational activities are achieved. The control system of the experimental model of the
proposed control system upgrades the elevator model to
electrical elevator. Originally the elevator system
work as a modern elevator while preserving the
possibility of working under the old classical control was working under classical relay control, and the
system. suggested one is digital and operated under PC
control. Operation of this system is managed by a
Keywords: Data Acquisition Controller, LabJack, suitable visual basic program [1, 4].
Elevator, Visual basic, Upgrade.

THE EXPERIMENTAL MODEL OF THE

INTRODUCTION
ELEVATOR
Elevators are vertical lift transportation systems
that effectively move people between floors of The case study in this paper is an experimental
buildings. Most are powered by electric motors that model of an electrical elevator which consists of a
pull steel cables along pulleys. real lift scaled down to 1:4. The Dimensions and
weight of it are 860x700x2400 mm – 230 kg. The
Automatic elevators began to appear as early as the model simulates all the characteristics, operations
1930s and their development was hastened by and structure of a full-sized lift for a three-story
striking elevator operators. These building with maintenance room. The lift includes
electromechanical systems used relay logic circuits real safety devices against rope breakage/stretching,
of increasing complexity to control the speed, and control devices for the normal and abnormal
position and door operation of an elevator or bank run of the cabin and fault simulator.
of elevators. The Otis Autotronic system of the Layout of the elevator model is shown in Figure 1.

© 2015 Mohammed M. Ezzaldean, open access article. Distributed under the terms of Creative
Commons Attribution (CC BY) license 4.0.
Ezzaldean et al, Journal of Control, Robotics, and Mechatronic Systems, ISSN: Pending, Vol. 1 (1), 22-26, Mar. 2015
DOI: Pending

Input
Power

Control Circuit
Ready check

Start
program

Elevator call button PC

Running Elevator
From
Read call signal
Read both call and
from PC and
position signals
position signal
from elevator
from elevator

Elevator at Floor x
Input2 = true

Press Press up
check down check check
R2=true
R1= true Press x
Or
Fig. 1: Layout of the elevator model. or
R2=true
R3=true

Main electrical characteristics of the experimental Nothing

If n2 and (R1 or R2) If n2 and (R3 or
model of the electrical elevator: then
Contactor M and
R2) then Contactor
M and Contactor D

 8-pole, 0.15 HP motor with an electric

Contactor D Contact Contact

brake.
 Limit switches, actuator and lock for Motor
operate Motor not
Motor
operate

control and blocking of doors and limit elevator

down
operate elevator
up

switches and switches for motion and

stopping the cabin at floors.
 External pushbutton panel represents the Ready to next task
cabin control panel, and three call
Fig. 2: Flow chart of operation procedure of the
pushbutton panels for each floor.
The general algorithm by which the elevator can elevator.
decide where to stop, is summarized as follows:
 Continue traveling in the same direction
(up or down) while there are remaining  When it receives a call, the door will be
requests in that same direction. blocked by releasing the actuator and it will
 If there are no further requests in that
respond to that call.
direction, then stop and become idle, or
change direction if there are requests in the  When the elevator doors have locked, the
opposite direction. elevator will start to move to the intended
floor.
ELEVATOR WORKING PROCEDURE  As the elevator moves between floors, the
limit switches detects that the elevator is
Referring to the flow chart shown in Figure 2, approaching a specific floor and notifies the
the procedure of operation of the elevator model
can be summarized as follows [1, 2, & 5]: system.
 The normal condition of the elevator is  The system checks whether the elevator
staying at one of the floors at a ready should stop at this floor or not. If so, the
condition (i.e. not requested neither from system commands the driving motor to stop
floors nor the car). and the brake system to operate.

23
Ezzaldean et al, Journal of Control, Robotics, and Mechatronic Systems, ISSN: Pending, Vol. 1 (1), 22-26, Mar. 2015
DOI: Pending

 When the elevator has stopped, the system ELEMENTS AND DESCRIPTION OF
commands the actuator to open the lock of THE SUGGESTED CONTROL SYSTEM
the door. In this work, a new control system of the
 The elevator will be ready for the next task. elevator is suggested and developed. This system
The circuit diagram of classical control of the consists of a PC and a data acquisition system. By
experimental model of the electrical elevator is
shown in figure 3. using the proposed control system the elevator
model will be able to work like a modern elevator
system. The elements of this system are:

 Data acquisition system (Labjack U12):

LabJack U12 is a multifunctional, low-cost
interface that provides a reliable connection
between the PC and the physical world.
This measurement and automation device is
generally used for measurements, data
logging, data acquisition and control
applications. Its connection to the PC in
MASIS is via the supplied USB cable.
LabJack U12 can be used with various
softwares, such as C++, Lab VIEW, Visual
basic, DASYLab and MATLAB [6].
 Inputs/Outputs circuit: LabJack U12 has
different and redundant protection
A mechanisms, however the inappropriate use
of the device can damage it and/or the
connected PC. An Inputs/Outputs circuit is
built to enhance the protection for LabJack
U12 and the PC.
 Balance of the system: other elements are
used in the control system. These elements
are a power supply, transformer, bridge
rectifier, contactors and fuses.

Inputs/Outputs circuit connects the elevator with

LabJack U12. It takes the input signals from call
buttons and limit switches of the elevator and
transfers them to the data acquisition system. The
Inputs/outputs circuit furthermore transfers the
output signals of LabJack U12 to the elevator
model. The circuit diagram of the control system is
shown in figure 4.
B
Fig. 3: Circuit diagram for the classical control of
the experimental model.
24
Ezzaldean et al, Journal of Control, Robotics, and Mechatronic Systems, ISSN: Pending, Vol. 1 (1), 22-26, Mar. 2015
DOI: Pending

Fig. 5-b: Main form of the visual basic program

(during run).

The operation of the proposed control system was

tested and all the required activities of the elevator
model were achieved. The connection of the new
Fig.4: Circuit diagram of the digital control system. control system is arranged in such a flexible
manner that the elevator model could be operated
The algorithm of operation of the elevator is either under control of the original classic control
developed as a visual basic program. This program or under control of the new digital control circuit
manages the operation of the elevator model and it [7, 8]. Layout of the elevator model while it
is formulated as three parts: operates within the proposed control system is
 Reading the signals from the elevator shown in figure 6.
model.
 Processing the signals and specifying the
proper order.
 Sending the orders to the elevator model.
The main form of the visual basic program is
shown in figure 5, a and b.

Fig. 6: The elevator model operated with the digital

Fig. 5-a: Main form of the visual basic program control system.
(before run).

25
 Ezzaldean et al, Journal of Control, Robotics, and Mechatronic Systems, ISSN: Pending, Vol. 1 (1), 22-26, Mar. 2015
DOI: Pending

CONCLUSION
In this paper, a new digital control system is
proposed. This control system is designed to
improve the classical model of the elevator's control
system. Basically, the operation of the new control
system is matched with the old one, nevertheless
the proposed control offers many advantages like:
1. It behaves like the control of the modern
elevator.
2. It is upgradable where by modifying the
software's different modes of operation can
be obtained.
3. It is more flexible for educational and
training purposes.

REFERENCES
[1] Amer Abed Mansour Al-Mesaody; Design and
Implementation of an Elevator Simulator
Controlled by a PLC, M.sc thesis, University of
Technology - Baghdad, 2007.
[2] G. C. Barney, Elevator Technology, Published
for The International Association of Elevator
Engineers by Ellis Horwood Limited,
Publishers. Chichester, 1986.
[3] Harvey M. Sachs, Opportunities for Elevator
Energy Efficiency Improvements, American
Council for an Energy-Efficient Economy, 2005
http://www.aceee.org.
[4] George R. Strakosch, Jaros, Baum &
Bolles, Vertical Transportation: Elevators and
Escalators; JOHN WILEY & SONS, 2nd
edition, 1983.
[5] Ford, M.; New Elevator Technology: The
Machine Room-Less Elevator Architectural
Record. McGraw Hill Financial. Retrieved
2009.
[6] http://LabJack U12.com.
[7] Ashish Tewari, “Modern Control Design”, John
Wiley & Sons. Ltd., 2002.
[8] Barney, G., C., “Elevator Traffic Handbook”,
Taylor & Francis Group, 2003.

26

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Laboratory model of the elevator controlled by ARDUINO platform

Conference Paper · May 2017

DOI: 10.23919/MIPRO.2017.7973670

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University of Applied Sciences Zagreb Polytechnic of Zagreb
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 Laboratory Model of the Elevator Controlled
by ARDUINO Platform
Marijo Andrija Balug*, Tomislav Špoljarić** and Goran Vujisić**
* Faculty of Electrical Engineering and Computer Science, Maribor, Slovenia
**University of Applied Sciences - Department of Electrical Engineering, Zagreb, Croatia
marioandrija.balug@student.um.si, tomislav.spoljaric@tvz.hr, gvujisic@tvz.hr

ABSTRACT - This paper presents methods for Mini development board, chopper and small DC
regulating the elevator's cabin speed and position for motor with permanent magnets.
purposes of traffic control. It contains four stations.
On every station there are two position sensors and A. Controller
cabin call button. Cabin speed regulation is realized ARDUINO Pro Mini (Fig 2.) development
with microcontroller, incremental encoder and board is used as a PI controller. PI controller is
chopper, where chopper controls DC motor speed. A implemented using the PID library. The process has
simple traffic control is written for ARDUINO
only one dominant pole so it can be controlled quite
platform.
well with a PI controller. PI controller parameters
I. INTRODUCTION are obtained with experimental method, and uses
difference between reference value which is set by
This paper will show how to regulate elevator's another microcontroller and feedback value as an
cabin speed and position for purpose of traffic
input. First the proportional gain is increased to get
control. It is necessary to achieve speed regulation
a little overshoot and then the intagral constant is
due to speed limitations, acceleration and
deceleration. In that way a cabin snatch can be deacreased from large value to small to obtain the
solved. Position regulation is needed because the response with given overshoot. Output is a PWM
cabin needs to stop on preferred position. All signal with modifiable duty-cycle.
functions are realized with two ARDUINO
development boards (Pro Mini and Mega board)
they are easy to program and they easily control
another elements of control systems. The elevator
model was made with the aim of acquiring
knowledge of automation and regulation. The
picture of model is given in Fig 1.

Figure 2. Overview of an ARDUINO Pro Mini board

TABLE I. ARDUINO PRO MINI TECHNICAL CHARACTERISTICS

Microntroller type ATmega328p

Operating voltage 5V
Power supply 5-12V
Digital I/O 14 (6 PWM outputs)
Analog inputs 6
Flash memory 32 KB
SRAM 2 KB
EEPROM 1 KB
Clock 16 MHz

Figure 1. Laboratory model of the Elevator

II. DC MOTOR SPEED REGULATION

The speed control loop contains microcontroller
ATmega328p, which is a part of ARDUINO Pro
 Figure 3. Parallel PI regulator block scheme [5]

PI transfer function is as follows [3, 5]:

1 + 𝑠𝑇 1 + 0.25𝑠 Figure 5. Steady state characteristics characteristic of an
F(s) = K ∗ = 0.5 ∗ = H-bridge
𝑠𝑇 0.25𝑠
0.5 ∗ (
1
+ 1) = 0.5 +
2
(1.)
C. DC Motor
0.25𝑠 𝑠
DC motor with permanent magnets is used as an
operating machine. The only known data about the
B. H-Bridge motor are armature voltage which is 12 V and
rotation speed which is 120 rpm. To get the transfer
H-bridge is used to control direction and speed function of this motor, this data was insufficient.
of DC motor. Inputs of H-bridge are connected to Dependence between rotation speed and armature
ARDUINO Pro Mini which controls direction and voltage was measured with tachogenerator, and
PWM duty-cycle. Output of an H-bridge is a voltage transfer function was obtained with MATLAB’s
between 0 V and 12 V, and which depends on System Identification Toolbox [4]:
input’s duty-cycle. It is connected to a DC motor
armature. 𝜔(𝑠) 𝐾𝑝
𝐹(𝑠) = = =
𝑈𝑎 (𝑠) (1+𝑠𝑇𝑝1 )(1+𝑠𝑇𝑝2 )

𝐾𝑝 0.9124
= (3.)
1+𝑠(𝑇𝑝2 +𝑇𝑝1 )+𝑠 2 𝑇𝑝1 𝑇𝑝2 1+0.321𝑠+0.011𝑠 2

Figure 4. Electrical scheme of an H-bridge [2]

Transfer function of a H-bridge is as follows: Figure 6. Input-output characteristic of a DC motor obtained

from measurements
𝑈𝑂𝑈𝑇 (𝑠)
𝐹(𝑠) = = 𝐾 = 2.43 (2.)
𝑈𝐼𝑁 (𝑠)
D. Incremental Encooder
and its characteristic is shown on Fig.5. DC motor rotation speed is measured with
incremental encoder (Fig 7.). Incremental encoder
gives 600 impulses per rotation. Output is
connected to ARDUINO Pro Mini which counts
impulses in time and is used as a regulation circuit
feedback. Maximum input in encoder is 13.51 rad/s
and maximum output is 5 V.
 IV. POSITION AND TRAFFIC REGULATION
A. ARDUINO Mega
ARDUINO Mega development board (Fig 10.) is
chosen for position and traffic control. This board is
chosen because it has enough digital inputs and
outputs to connect outputs of 8 position sensors, 8
buttons for cabin calling and few pins to
communicate with ARDUINO Pro Mini.

Figure 7. Incremental encoder

Teherefore the transfer function of incremental

encoder is:
𝑦(𝑠) 5
𝐹(𝑠) = = = 0.37 (4.)
𝜔(𝑠) 13,51

III. SPEED REGULATION FEEDBACK LOOP

Reference value is voltage between 0 V and 5
V. It is set on analog input of microcontroller. If the
reference value is set to 5 V, then DC motor Figure 10. Overview of an ARDUINO Mega board
rotation speed is 13.5 rad/s. Output of measuring
element is value between 0 and 5. Regulator input TABLE II. ARDUINO MEGA TECHNICAL CHARACTERISTICS
uses difference between referent value and output Microntroller type ATmega2560
of measuring element. Depending on the difference, Operating voltage 5V
on the output of the regulator 500 Hz PWM signal Power supply 7-12V
with modifiable duty-cycle appears. PWM signal is Digital I/O 54 (15 PWM outputs)
used as an input value to H-bridge. DC motor Analog inputs 16
rotation direction is chosen by Arduino Mega I/O current 20 mA
which sends information of direction to ARDUINO Flash memory 256 KB
Pro Mini. Arduino Pro Mini generates PWM signal SRAM 8 KB
with which controls DC motor speed via H-bridge. EEPROM 4 KB
DC motor is connected on the output of the H- Clock 16 MHz
bridge. Motor speed depends on PWM’s duty cycle.

B. Cabin position sensor

Cabin position sensor is an optocoupler. Paper
flag is mounted on the cabin, and it goes through
sensors. When the flag is between IR diode and
photo transistor, sensor output is 0 V, else output is
5 V. Depending on sensors outputs microcontroller
determines cabin position. Elevator model has eight
sensors, two on every station.

Figure 8. Simulink model of speed control feedback loop

Figure 11. Electrical sheme of an optocoupler

Figure 9. Speed control time response
 C. Traffic control D. Principles of operation of the elevator system
There is a call button (Fig. 12.) on every of four If the system is turned on for the first time,
stations. Four buttons are mounted in the cabin. microcontroller checks cabin position. If the cabin
They are connected to digital inputs of is not on the first station, microcontroller positions
microcontroller. Algorithms in microcontroller save cabin on first station. After that, microcontroller
every button call and send cabin to the first saved constantly checks call button and position sensors
value. change of state. When the call is active,
microcontroller calculates difference between
stations and sets reference value of speed and
direction of moving cabin to the speed control
circuit. When the cabin is on the wanted position,
microcontroller sends zero as speed reference and
the cabin stops.
V. CONCLUSION
The elevator model is made with the aim of
acquiring knowledge of automation and regulation.
It is useful for laboratory exercises because the
Figure 12. Electrical scheme of a call button
parameters of regulator are easy to change. If the
An elevator has four stations and the cabin parameters are changed, then the speed of cabin
speed depends on difference between current will be different.
position and position where cabin needs to go. If Benefits in using such system are:
the cabin needs to go from the first to second  ARDUINO platform is easy to program
station, referent speed needs to be minimal because and is compatible with many operating
the distance is small. Also, acceleration and systems,
deceleration depends on difference between  it is easy to change elements and their
stations. Algorithm in microcontroller calculates the parameters in code,
difference and constantly sends parameters to  it is possible to measure all signals
second microcontroller. It sends reference value of between microcontrollers and other
speed and cabin direction. Reference value has the elements.
shape of PWM signal, because microcontroller does However, there are certain disadvantages. They
not have analog outputs. PWM signal is connected include:
to RC filter (Fig 13). The output is approximately  low operating voltage and possible
equal to average value of PWM signal and it is disturbances,
connected to ARDUINO Pro Mini analog input.  ARDUINO Mini Pro and Mega have not
Fig. 14 shows acceleration and deceleration speed enough interrupt pins, so microcontroller
reference ramps. needs to have additional algorithm to
constantly check changes of states on
digital inputs,
 optocouplers are not resistant to dust.
Electromagnetic sensors would be better.
In addition, some improvements to this system
can be done:
 adding the cabin door,
 changing DC motor with gear unit with
Figure 13. Electrical scheme of an RC filter
DC motor without gear unit because when
the cabin goes down the motor would be in
braking mode. In that way real elevators
work [6].
REFERENCES
[1] “ARDUINO Tutorials”, www.arduino.cc, 2016.
[2] “The H-bridge”, www.talkingelectronics.com, 2012.
[3] N. Perić, “Automatsko Upravljanje”, FER, Zagreb, 1998.
[4] M. Fruk, G. Vujisić, T. Špoljarić, “Parameter Identification
of Transfer Functions Using MATLAB”, 35th International
Convention, MIPRO, Opatija, 2012.
[5] Fruk M., “Bilješke s predavanja iz kolegija Automatsko
Upravljanje”, interna skripta, TVZ, Zagreb, 2015.
[6] A. Jozić. T. Špoljarić, D. Gadže, “Laboratory Model of an
Elevator: Control with Three Speed Profiles”, 39 th
Figure 14. Change of a reference value
International Convention, MIPRO, Opatija, 2016.

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