SUGISAKAMASANORI

Journal of Advances in Artificial Life Robotics
Vol. 1(1); June (2020), pp. 50–55
ON LINE ISSN 2435-8061; ISSN-L 2435-8061
https://alife-robotics.org/jallr.html

Research Article

A Study on Prevention of Predictive Failures
Tsutomu Ito1, Takao Ito2, Makoto Sakamoto3

Department of Business Administration, National Institute of Technology, Ube College, 2-14-1 Tokiwadai, Ube City, Yamaguchi Pref.,755-8555, Japan
Graduate School of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi Hiroshima, 739-7527, Japan
3
Faculty of Engineering, University of Miyazaki, 1-1 Gakuen Kibanadai-Nishi, Miyazaki, 889-2192, Japan
12ARTICLE INFO
Article History
Received 25 November 2019
Accepted 18 July 2020
Keywords
Motor brake
Brake gap
Acceleration
Maintenance

ABSTRACTElectric motors play an important role as the primary power for conveyor and drop lifts in
manufacturing systems especially in automobile manufacturing factories. Many electric motors
equipped with brake systems have sensors that determine where they should stop. This brakesystem needs to be maintained to keep proper brake gap consistent. Measuring the brake gap ofelectric motors is one of the main jobs of maintenance department, but this is a difficult task
because most of the motors are located in unsafe spaces, like the upper end or under the lift pit.
This paper proposes a new approach to measure the brake gap of motors to reduce maintenancerisks, thus saving costs. The method suggests using vibration acceleration to measure the motor
gap in running production system based on mechanical model. The effectiveness of this researchis indicative by experience results.

© 2022 The Author. Published by Sugisaka Masanori at ALife Robotics Corporation Ltd.
This is an open access article distributed under the CC BY-NC 4.0 license(http://creativecommons.org/licenses/by-nc/4.0/).

This paper is structured as follows. Section 2 reviews therelevant literature on brake measurement. Section 3
explains the structure of motor brake. Section 4 shows
calculation and discussions. Section 5 identifies
experiment apparatus and condition. Experimental
results and discussion are provided in Section 6. Section
7 explains directions for future research.

1. Introduction
As the main power source of conveyors and lifts in
manufacturing systems, electric motors play an importantrole in automobile assembling lines as well as othermachines. Known as motors with brakes inbuilt, theirfunction is to improve the accuracy of machinery
stopping when required. Most of these mechanisms havebrake linings, which wear out over long-term use. To
maintain the braking function, the necessitates measuring
and tuning the brake. The dominant approach of
measuring the brake gap is usually reassembling thecover and measure the gap directly by maintenancepersonnel using thickness gage. From viewpoint of
securing the working place, most of the electric motors
are housed in the pit (under-ground) or above themachinery. Thus, it makes maintenance process
dangerous and inconvenient. To solve this problem,
manuscript proposes a new remote approach to measure
the brake gap without reassembling the motor based onmechanical model.

2. Background
Motor braking tests is a primary determinant of motor
performance, which has been the subject of many
investigations. For example, Bhau, Patil and Samantpresented methodologies used for automotive service
brake testing for two wheelers. The main contribution of
their study was to compare and contrast three main braketesting standards, viz., Indian Standards, Federal Motor
Vehicle Safety Standards and European Economic
Commission Standards [1]. Seyfert, in his study,
introduced technical tips about brake maintenance [2].
Sangtarash et al. explained simulation procedures forseries braking with optimal braking feel, series braking

Corresponding author’s E-mail: t_ito@ube-k.ac.jp, itotakao@hiroshima-u.ac.jp, sakamoto@cc.miyazaki-u.ac.jp

50

with optimal energy recovery, and parallel braking
strategies using CRUISE software [3]. All these studiesfocused on different aspects of motor braking systems,
but studies on industrial motor maintenance have beensparse. In assembly line, many electric motors equippedbrake system are required to determine where they shouldstop. This brake system need to be maintained to keep
proper brake gap. Measuring the brake gap of electricmotors is one a key job of the maintenance department,
but entail significant difficulties because most of themotors are housed in unsafe spaces, such as at the upper
end or even under the lift pit. In this study, the authorspropose a new approach to measure the brake gap ofmotors to reduce maintenance risks and save costs. The
method is using vibration acceleration to measure themotor gap in running production system based onmechanical model. To our best knowledge, this is the firststudy that measures the brake gap without machinery
stopping.

Fig. 2. An Image of Free Position Relationship between
Brake Lining and Friction Plate.

3. Structure of motor brake
Major motor brake consists of a brake lining, friction
plate and actuator. An example of motor brake is shownin Fig.1.
The brake lining is attached to main shaft of motor.
Brake lining spins with main shaft of motor freely whenbrake is free. If brake is activated, friction plate pushes
the brake ling by actuator. Typical type of actuator uses
coil spring to push the friction plate, and electricalmagnet to release brake. Fig.2 and Fig.3 show an imageof brake free and brake locking relationship between
brake lining and friction plate respectively.

Fig. 3. An Image of Locking Position Relationship between
Brake Lining and Friction Plate.

4. Calculation and Discussions
Motor brake is activated by coil spring in actuator to push
the friction plate. The structure of our models is shown inFig.2 and Fig.3, respectively.
On real motors, some coil springs are used, but they
can be constructed as one modelled spring with spring
rate k[N/m], m[kg] for math of friction plate and brakelining, and ∆x[m] for brake gap. The energy this systemdispenses is formulated in equation (1).
121(1)𝑘𝑘(2)𝑘𝑘∆𝑥𝑥 2 = 𝑚𝑚𝑣𝑣 22v = � ∆𝑥𝑥
𝑚𝑚Fig. 1. A Typical image of Motor with Brake.

This energy system vibrates the motor when the brakeis activated. Equation (2) shows the relationship of ∆xand v[m/s]. Here v[m/s] indicates the instant velocity
51

practical viewpoint, this is expected if it is possible thatthe fan cover attached is available to be used. Second, anexperiment to find out the linearity of vibration
acceleration and brake gap was conducted. To
demonstrate the several gap, the authors used shim tapeto make the clearance between bake lining and friction
plate. (A typical picture is shown in Fig.4.)
Vibration acceleration data were collected as plus
acceleration and minus acceleration, thus the absolute
number and average of 6 times of vibration—as is thenorm—was employed. Fig. 5 shows an image for datacollection.

when the friction plate hits the brake lining. However,this velocity is difficult to measure. However, based on
momentum conservation law, the relationships ofacceleration to the brake gap is calculated in theequations below.
m𝑣𝑣 , − 𝑚𝑚𝑚𝑚 = 𝐹𝐹∆𝑡𝑡

(3)

𝑚𝑚

𝑘𝑘(4)

𝑘𝑘(5)

𝑥𝑥̈ = 𝛽𝛽𝛽𝛽(6)F=𝑥𝑥̈ =,𝑣𝑣 = 0∆𝑡𝑡

� 𝑥𝑥

∆𝑡𝑡

𝑚𝑚

1𝑚𝑚� 𝑥𝑥∆t signifies a very small amount of time, so it is hardto measure. However, by transforming it as equation (6),the linear relationship between brake gap andacceleration becomes evident. This suggests that measure
the vibration acceleration can be used for brake gap.
5. Experiment Apparatus and Condition
Experiment apparatus and conditions are shown below,
respectively.
5.1. Experiment Apparatus
A set of experimental apparatus is shown in Table 1.
Maker

TypeSUMITOMOHEAVYINDUSTRESGEARMOTORSINDUCTION MOTOR
0.2kw 4P 3φ

KEYENCENR-600

KEYENCE

NR-CA04

KEYENCE

NR-U65KEYENCE

Wave Logger pro

Acceleration pickup

SHOWA SOKKI

2304A , Sensitivity
47.6pC/G ,4.86pC/(m/s2)
Capacitance 780pF

Shim tape

TRUSCOTFG-0.05M1

Motor
Data logger
Amplifire ofacceleration pickup
Data logger
softwareFig. 4. Experimental Condition.

Table. 1 Experimental apparatus.
5.2. Experiment Condition

Fig. 5. An Image for Data Collection.

The authors attached the acceleration pick up to motors
fitted with magnets. First, an experiment was conductedto confirm the effect of the presence (or absence) of a fan
cover on the measurement result of acceleration. From a52

6. Result and Discussion

250

Acceleration [m/s2]

6.1. Comparative study with cover

Acceleration [m/s2]

To clarify the effect of the presence (or absence) of a fan
cover on the measurement result of acceleration, twoexperiments were conducted. The first measured theacceleration with fan cover and the second experiment
was conducted without the fan cover. Fig.6 shows theresult of these experiments.
Measuring points, A and B are circumferential
directions, whereas C is axial direction. It is expected thatmeasuring acceleration without the cover would behigher than that with the cover. Thus, it is better tomeasure the acceleration without cover. On the otherhand, a hard point of the motors case transmit vibration
directly to the outside of the motor case. Result of point
A shows the possibility of measuring vibration without
reassembly the fan cover.

Without cover0A

B

50
0.26

0.36

0.46

0.56

0.66

0.76

Fig. 7. Relationship between Acceleration and Brake gap.

The relationship between experimental result andcalculated with the coefficient k [N/m] is shown in Fig.
8.
Additionally, a t-test was added to the experimental
result and shows a statistically significant difference of
the acceleration between 0.2[mm] of brake gap.

150
50100

Brake gap [mm]200

With cover

150

0250

100200C

Point of measurment

Fig. 6. Difference of Acceleration between Experiments with
Cover and without Cover.
Fig. 8. Relationship between Theoretical Result andExperiment Result.

6.2. Relationship of Acceleration and Brake Gap
To illustrate the linear relationship between measured
acceleration and brake gap, an experiment with brake gap
between 0.26[mm] to 0.76[mm], difference of 0.05[mm]conducted. Based on the findings shown in Fig.7, a linear
relationship between acceleration and quality is observed.
Calculated coefficients of k [N/mm] for each gap arereported in Table 2.
Gap[mm]

0.26

0.36

0.46

0.56

0.66

0.76

AverageK[N/m]

248.5

364.3

317.5

301.7

276.3

292.2

300.1

Table. 2 Coefficient K[N/m] of each Brake Gap53

7. Conclusion
In this study, a new approach to measure the brake gap
was proposed. According to the results of theexperimental data analysis, the method to measure brake
gap with accuracy 0.2mm was observed. The
implications are that electrical measurement systems
should be operated among IoT system in the future.

============================================

Authors Introduction

Dr. Tsutomu ItoReferences

He is an assistant Professor in
Departmentof
Business
Administration, National Institute ofTechnology, Ube College. He has
published many papers in refereed
journals and proceedings, particularlyin the area of industrial management,and computer science. His current
research interests include internet ofthings (IoT), mechanical engineering, artificial intelligence(AI), automata theory, quantitative analysis of Japanese
Keiretsu. He was one of the winners of the Best Paper Awardin the International Conference on Artificial Life andRobotics (ICAROB) in 2015and 2016. Dr. Ito earned hisDoctor degree of Engineering from Hiroshima University,
Japan in 2018.

1. Bhau Kashinath Kumbhar, Satyajit Ramchandra Patil,
Suresh Maruti Sawant: A Comparative Study on
Automotive Brake Testing Standards, Journal of The
Institution of Engineers (India): Series C, Volume 98,Issue 4, pp 527–531, 17 June 2016,
2. Karl Seyfert, Preventive Maintenance Tech Tips: BrakeMaintenance, March 2004 Issue,.
3. Farhad Sangtarash, Vahid Esfahanian, Hassan Nehzati,Samaneh Haddadi, Meisam Amiri Bavanpour and BabakHaghpanah, Effect of Different Regenerative Braking
Strategies on Braking Performance and Fuel Economy ina Hybrid Electric Bus Employing CRUISE Vehicle
Simulation, 23 June 2008, SAEE International,

Dr. Takao Ito

He is Professor of Management ofTechnology (MOT) in Graduate SchoolofEngineering
at
Hiroshima
University. He is serving concurrentlyas Professor of Harbin Institute ofTechnology (Weihai) China. He haspublished numerous papers in refereed
journals and proceedings, particularlyin the area of management science, and computer science.
He has published more than eight academic books including
a book on Network Organizations and Information (JapaneseEdition). His current research interests include automata
theory, artificial intelligence, systems control, quantitative
analysis of inter-firm relationships using graph theory, andengineering approach of organizational structures using
complex systems theory.

54Dr. Makoto Sakamoto
He received the Ph.D. degree incomputerscienceandsystems
engineering
fromYamaguchi
University. He is presently an associate
professor in the Faculty of Engineering,
University of Miyazaki. He is atheoretical computer scientist, and his
current main research interests areautomata theory, languages and computation. He is alsointerested in digital geometry, digital image processing,computer vision, computer graphics, virtual reality,
augmented reality, entertainment computing, complex
systems and so on.
============================================

55