Instrumentation & Measurement Magazine 24-4 - 49

A New Structural Health
Monitoring Approach Based on
Smartphone Measurements of
Magnetic Field Intensity
Ali Matin Nazar, Pengcheng Jiao, Qianyun Zhang,
King-James I. Egbe, and Amir H. Alavi
I
n this paper, a new structural damage detection approach
is proposed, based on monitoring of the magnetic field
intensity variations using smartphones. Experimental
and numerical studies are conducted on steel plates to verify
the efficiency of the proposed approach. Various damage scenarios
are introduced to the steel plates. Then, a smartphone
magnetometer sensor is deployed to measure the changes of
the magnetic flux due to damage progression. The experimental
and numerical results agree well with each other. Based on
the results, the magnetic field intensity increases as the damage
progresses. Furthermore, the damage detection accuracy
declines as the distance of the smartphone increases from the
steel plate surface. The proposed method can be considered as
a promising, cost-effective and crowdsourcing sensing platform
empowered by citizens for structural health monitoring
of civil infrastructure systems.
Introduction to Structural Health
Monitoring
Age-related degradation, deferred maintenance, natural disasters,
and man-made hazards are seriously threatening
structural systems around the world. Degradation of civil infrastructure
systems results in massive losses and failures [1], [2].
The challenges associated with the age-related degradation has
exacerbated the need for robust structural health monitoring
(SHM) methods capable of identifying and evaluating different
structural damage types [3]-[7]. A number of studies have
been conducted to harness the power of new technologies such
as wireless sensors [8]-[10], fiber optic sensors [11]-[13] and radar
system interferometry [14] for improving traditional SHM
systems. Despite the efficiency of the existing SHM methods,
they have their own disadvantages and executive limitations.
Currently, installation and maintenance of SHM systems
poses technical difficulties and economic issues. Moreover,
continuous collection of information about the health status
of a structural system is costly and requires remarkable manpower.
These issues imply a need to develop cost-effective
SHM methods that still offer reliable functionalities [15]-[17].
In recent years, researchers have noticed that smartphones
can be used for crowdsourced collection of environmental
information. Smartphones are equipped with a number of sensors
that can be used for missions other than the ones they are
originally designed for. Some examples are GPS, accelerometers,
magnetometers, and proximity sensors that can provide
useful information to users (Fig. 1). In general, the smartphone
systems support three main groups of sensors as shown in Fig.
2. Acceleration, gravity and rotational sensors are included in
the motion sensing category. Environmental sensors include
temperature control systems, humidity, lighting and air pressure
gauges. Orientation and magnetometer sensors belong to
Fig. 1. Demonstration of different types of smartphone sensors.
This research is funded in part by the Key Research and Development Plan of Zhejiang, China (grant numbers: 2021C03180,
2021C03181), the Fundamental Research Funds for the Central Universities, China (grant number: 2020-KYY-529112-0002), the
Chinese Government Scholarship (grant number: 2019ZFY011294), and the China Scholarship Council
(grant number: 2019S0A023394).
June 2021
IEEE Instrumentation & Measurement Magazine
1094-6969/21/$25.00©2021IEEE
49

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