Article citation information:
Galant, M., Merkisz, J. Analysis of the possibilities of using EEG in
assessing pilots’ psychophysical condition. Scientific
Journal of Silesian University of Technology.
Series Transport. 2017, 95, 39-46.
ISSN: 0209-3324.
DOI: https://doi.org/10.20858/sjsutst.2017.95.4.
Marta GALANT[1],
Jerzy MERKISZ[2]
ANALYSIS OF THE POSSIBILITIES
OF USING EEG IN ASSESSING PILOTS’ PSYCHOPHYSICAL CONDITION
Summary. An excessive load on an operator’s
cognitive system can cause deterioration in perceptual abilities, decreased
reaction time and increased probability of making an incorrect decision, which
in turn can lead to a dangerous situation. Researching the cognitive load of an
operator can therefore contribute to safer transportation. While there are many
methods used in the study of cognitive load, they can be classified as either
subjective assessments or objective assessments.
This paper presents an analysis of the possibilities of using
electroencephalography in assessing the psychophysical condition of the pilot.
The investigation was conducted in the Simulation Research Laboratory in the
Institute of Combustion Engines and Transport at Poznan University of Technology.
Keywords:
EEG; simulator; pilots’ psychophysical condition.
1. INTRODUCTION
Cognitive load refers to the total
amount of mental effort used in the working memory. A heavy cognitive load
typically causes errors or some kind of interference in the task being
conducted [11]. Excessive load may cause deterioration in perceptual abilities,
decreased reaction time and increased probability of making an incorrect
decision, possibly leading to dangerous situations that may result in an
accident. Studies about cognitive load can therefore contribute to safer
transportation. The only possible and effective method to avoid these risks is
to monitor the operator’s cognitive load.
The term “cognitive load” refers to
the operator’s demand on his or her cognitive resources. In a situation where
demand exceeds a certain limit, the quality of the performance of tasks
significantly decreases [1]. For a pilot, excessive cognitive load can result
in the wrong selection of flight data, errors in the assessment of the
situation, or problems with maintaining certain flight conditions. Appropriate
monitoring of an operator’s cognitive load could lead to a reduction in the
number of errors made as a consequence of insufficient cognitive resources [6].
There are several methods used in
studies of cognitive load, which by nature can be divided into subjective and
objective assessment methods. Subjective methods includes the NASA-TLX
questionnaire and the SWAT (Subjective Workload Assessment Technique).
Objective methods are more frequently, which include measuring the heart rate
and galvanic skin response, electroencephalography, functional magnetic
resonance imaging, oculography studies, testing the activity of the
cardiovascular system, the rate and depth of breathing, and positron emission
tomography [5].
The article presents considerations
for the use of the electroencephalogram (EEG) signal in studies involving the
application of simulators. In recent years, simulators have become an inherent
feature in research. The extent to which reality is represented by high-class
simulators nowadays appears to be sufficient for laboratory research [9].
2. THE ESSENCE OF SIMULATION STUDIES
The issue of transport safety has
inspired research, with the aim of improving the ability of operators (drivers,
pilots etc.) and understanding the causes and relationships related to their
behaviour. Often it is impossible or even too risky to recreate dangerous
situations in order to analyse the causes of their occurrence. Therefore, for
the purpose of research, simulators are frequently used. An important advantage
when using simulators in research is the ability to control many factors, as
well as record a number of variables, including the parameters of an operator’s
physiological and psychological condition [3, 7, 8, 13]. The use of simulators
also allows for studies to be conducted, which can realize the full
normalization of test conditions [4]. The repeatability of scenarios means that
the behaviour of different operators under the same conditions or the same
operator under different situations can be compared, which is not possible in
real traffic conditions.
The dynamic development of
simulation technology, as observed in the last two decades, has meant that the
number of simulator applications has increased in all areas. Today,
considerable attention is being paid to the way in which flight simulators can
improve the level of aviation safety. Their advantages are particularly
appreciated in the implementation of research and pilot training. There are
known examples of when flight simulators are used to help trainee pilots master
the techniques of piloting or warfare using military aircraft. As there are
also types of aircraft for which tandem flight controls have not been produced,
simulators offer the opportunity for complete training to be successfully
carried out [12]. The use of flight simulators can significantly reduce the
cost of pilot training. Besides teaching and training procedures, simulators
can be used to conduct research and teaching in a wide range of disciplines.
Apart from the advantages, there are
also some negative aspects to the use of simulators in research, such as
simulator sickness. In addition, it often happens that an operator in a virtual
environment becomes tired more quickly. However, the biggest disadvantage is in
fact a feature that has been previously mentioned as an advantage: namely,
safety. The operator in a simulator knows that he or she is safe, and there is
nothing to be afraid of, which can cause him or her to perform manoeuvres that
he or she would not perform under real flight conditions.
3. CKAS MOTIONSIM5 SIMULATOR
The Simulation Research Laboratory
in the Institute of Combustion Engines and Transport at Poznan University of
Technology is equipped with a CKAS MotionSim5 simulator. The device has been
manufactured by CKAS Mechatronics Pty. Ltd. from Australia.
It is a system that uses software
and hardware, combined with modern desktop computer equipment on a custom-built
motion platform, comprising a cockpit that provides control devices that are
identical or similar to those found on real aircraft. The MotionSim5 is a
four-seater platform based on an electrical motion system with six degrees of
freedom. This makes it possible to obtain a high level of accuracy in the
performance of movement. The system tilts the hull in every possible direction
at an angle of 18° and moves it 150 mm [2].
The MS5 Visual System, which
provides a wide 200°×40° field of view with high resolution, consists of three
full-HD (1,920×1,080 pixels) front-surface DLP projectors, three high-end PCs
for image generation, and a screen. An additional PC is used to drive flight
instruments and for general flight simulation.
b a
Fig. 1. CKAS MotionSim5 simulator: (a) exterior,
(b) interior
The CKAS MotionSim5 trainer is
designed to simulate four generic types of light aircraft: a piston
single-engine aircraft, a piston twin-engine aircraft, a light twin-engine
turboprop aircraft and a light jet. It is not intended to simulate a particular
aircraft model, but rather to represent a typical aircraft in each class in
terms of its handling qualities and features.
The Instructor Station provides
control over the flight simulator environment, such as weather, positioning,
malfunctions and real-time tracking and flight recording. Additionally, it is
possible to carry out operations from and to almost every airport in the world.
The software allows for controlling
the most important flight parameters: ALT (altitude), AGL (above ground level),
IAS (indicated airspeed), VS (vertical speed), Bank (the angular displacement
around the longitudinal axis, which passes through the plane from nose to tail
[10]), Pitch (the lateral axis, which passes through the plane from wing tip to
wing tip, with the pitch moving the aircraft’s nose up and down [10]). After
each flight, it is possible to record the parameters.
There are two kinds of generated
files [2]:
- CSV file (to create personalized
graphs), as presented in Fig. 2
- Google Earth file (showing the
flight profile, events and mistakes), as presented in Fig. 3
Fig. 2. Flight parameters (CSV file)
Fig. 3. Flight parameters (Google
Earth file)
4. ELECTROENCEPHALOGRAPHY
Electroencephalography is a
non-invasive method of neuroimaging, used to study bioelectrical brain activity
with an electroencephalograph. An EEG is defined as a variable electrical
activity, recorded from the surface of the scalp using the electrodes and
conductive media [8]. EEG measurement is completely non-invasive procedure,
which can be used on multiple occasions on one person, either an adult or
child, practically without risks or restrictions. The electrical activity of
the brain is formed by neuronal activity (related to the dissemination of information)
[3]. Each nerve cell produces internal and external fluid surrounding the cell.
This fluid is composed of water, protein and ions (positive and negative). As a
result of a sufficiently strong stimulus, the cell membrane permeability
changes occur for specific ions, while there are changes in the load inside and
outside the cell, which are referred to as action potentials. The difference
between the two potentials as a function of time is recorded by an EEG. In
other words, an EEG records the voltage measurement resulting from brain
activity [8].
In order to register the potential
between the electrodes, at least two electrodes are required. For better
results, more electrodes are typically used, which are placed at appropriate
locations on the scalp. Electrode locations and names are specified by the
International 10-20 system recommended by the International Federation of
Clinical Neurophysiology. For a standard EEG, 19 recording electrodes (plus
ground and system references) are used, with the graphic layout resembling a
wavy line, in order to capture changes in the amplitude of the electrical
activity of the brain in a certain period of time. The amplitude is typically
expressed in microvolts (mV), while frequency is expressed in hertz (Hz).
Cyclic bioelectric activity of the
brain, which is recorded during the test, is expressed in waves with a
frequency in the range of 1-100 Hz and an amplitude of five to hundreds of
microvolts. A normal adult’s EEG is usually measured in terms of standby, with
closed eyes, and in the course of performing a task. Recording with closed eyes
and standby usually consists of a regular and dominant alpha wave, whose
amplitude decreases from the occiput to the front of the head. Recording
individual frequency corresponds to a specific mental state [8, 14].
The basic
types of brain waves are as follows [3]:
- Delta wave (δ) (0.1-3 Hz)
- Theta wave (θ) (4-7 Hz)
- Alpha wave (α) (8-15 Hz)
- SMR wave (12.5-15.5 Hz)
- Beta wave (β) (16-31 Hz)
- Gamma wave (γ) (32-100 Hz)
The extent of the research and
observations determines what information can be obtained from the images of
brain waves. Studying the bioelectrical activity of the brain can be seen in
whichever state is examined. However, there are also negative results for
particular waves:
- Alpha waves are responsible for the
state of relaxation, so its excess in the record indicates disorders manifested
by a lack of motivation to work, as well as apathy, poor concentration and
distraction.
- Beta waves indicate the rhythm of
readiness and are divided into beta 1 and beta 2. Beta 1 is the state when
the brain works quickly and efficiently; it depends on human will. Meanwhile,
beta 2 is a very fast wave. This may reveal evidence of the excessive
stimulation of the brain and nerve structures, which is reflected in
impulsiveness, hyperactivity, aggressive and rebellious behaviour. This occurs
in states of excitement, tension, nervousness, insomnia, irritability, trouble
and anxiety.
- SMR is a sensory rhythm responsible
for the storage and retention of information. When accompanied by extended
learning processes, it helps to maintain the equilibrium of the nervous system.
- Gamma waves occur during associative
processes and periods of intensive thinking.
- Theta waves are accompanied by
processes of meditation, hypnosis, intense dreams and emotions. At this
frequency, awareness can control physical pain, while the course of thoughts
becomes inconsistent. Logical relationships disappear, as seen in the case of
mental processes during sleep. Occurrence of a theta wave leads to a reduction
in stress, as well as increased creativity, awakened intuition and memory.
- Delta waves appear during intense
mental effort and deep sleep.
The correct EEG in humans at rest
with closed eyes should consist mainly of alpha and beta rhythm. In healthy
people, theta waves are recorded or the record is flattened. Any distortion,
disappearance or asymmetry of rhythm, as well as the presence of pathological
waves (theta, delta and other complex elements), confirms an incorrect test
result.
The advantages of
electroencephalography are as follows: relatively low cost, non-invasive and
perfect time resolution. EEG observation allows for keeping track of which
areas of the brain are active, although EEGs offer poorer spatial resolution.
The EEG has clinical applications in humans and animals in order to [7]:
- Monitor alertness, coma and brain
death
- Locate the area of damage after a
head injury etc.
- Explore delivery paths (according to
evoked potentials)
- Monitor cognitive involvement (alpha
rhythm)
- Explore epilepsy and locate the
source of attacks
- Monitor the development of the human
and animal brain
- Study the effects of drugs on the
formation of convulsions
- Study sleep disorders and physiology
- Given its wide-ranging uses, electroencephalography
has contributed to the popularization of the method and the frequent use of
EEGs in scientific experiments.
5. SUMMARY AND A DIRECTION FOR FUTURE WORK
The
Simulation Research Laboratory in the Institute of Combustion Engines and Transport
at Poznan University of Technology was created to conduct research, with the
aim of improving the safety of air transport. The scope of activities within
the laboratory currently consists of three basic areas:
1)
Studying the influence of pilots’ psychophysical
condition on flight safety
2)
Analysing the proper operation of systems supporting
pilots
3)
Examining the suitability of a person to perform tasks
As demand to reduce the human factor
in accidents is still high, there is a growing interest in flight simulators
for training and research into pilots’ psychophysical condition. Thanks to
modern solutions, it is possible to examine changes in concentration, reaction
time etc. without compromising on direct threats to life and health, which
would be the case with research conducted under real-world conditions. An
additional advantage of this type of research is the ability to reproduce the
same conditions for an entire research group, which world would be impossible
in reality.
The article has analysed the
possibility of using the EEG signal to assess pilots’ psychophysical ability.
With this method, the level of concentration and relaxation, depending on the
performed task, can be estimated, while the effect of weather conditions or the
complexity of tasks on flight safety can be determined.
In the future, work is planned to
use other methods for the objective assessment of pilots’ psychophysical
condition. For example, it is planned to use EyeTracker to measure eye
movement.
This publication aims to present the
research capabilities of the Simulation Research Laboratory at Poznan
University of Technology.
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Received 11.02.2017; accepted in revised form 27.04.2017
Scientific Journal of Silesian
University of Technology. Series Transport is licensed under a Creative
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