HMI Report: Display Systems, Color Schemes, and Design Factors

This report provides a comprehensive overview of Human-Machine Interfaces (HMI). It begins with an introduction to HMI, explaining its role in facilitating interaction between humans and machines. The report then delves into the two primary types of HMI: traditional and web-based systems, highlighting their respective advantages and disadvantages. A significant portion of the report is dedicated to the display system, covering aspects such as analog and digital displays, pictorial and text displays, screen layouts, and the importance of color schemes in enhancing user experience and efficiency. The report also discusses the factors that contribute to the selection of an appropriate HMI system, emphasizing the need for careful consideration of various elements to ensure optimal performance and user satisfaction. Overall, the report aims to provide a clear understanding of HMI systems, their components, and the critical factors influencing their design and implementation.

HUMAN-MACHINE INTERFACE
Executive Summary:
Technology has being increasing day by day. Machines play a vital role in reducing the effort of
humans. It is necessary to have a connection to all those machines. A component that could be
able to have a human and machine interaction in a system is known as Human-Machine
Interface. This could consists of both the hardware and the software, which permits the input
from the user to be translated into signals that could be understandable by the machines and in
turn the required result will be given back to the user in a high-level language. In our paper we
have discussed regarding the traditional and the web based HMI system. The display system
and the screen background with the text colours and graphics has also been clearly explained.

SNO TITLE PGNO
1 Introduction 3
2 Traditional Human Machine Interface 3
3 Web-based Human Machine Interface 4
4 Display System 5
5 Alarms and Event 8
6 Factors that Contributes to choose HMI 9
7 Conclusion 9
References 10

Introduction:
The procedure for the construction of operator interface involves a bridge of communication
between the processor and the Human Machine Interface (HMI) (Anderson, and Davies, 2010).
A component that could be able to have a human and machine interaction in a system is known
as Human-Machine Interface. This could consists of both the hardware and the software, which
permits the input from the user to be translated into signals that could be understandable by
the machines and in turn the required result will be given back to the user in a high-level
language. They have been widely used in electronics, military, medical, entertaining industries
and so on. This helps in the integration of humans with the complex technologies. HMI is also
known as Man-machine Interface (MMI) or human-computer interface or the vice versa. HMI is
of two types: 1) human to machine 2) machine to human. This technology is ubiquitous that
could have several sensors, several input and output devices, voice recognition peripherals and
other interfaces that could exchange the information in the form of sound, sight, heat and
several physical as well as cognitive ways, which are said to be the part of MMI.
HMI could also act as the adapter for several devices that is said to be a standalone
technological area. The key behind the construction involves the human capability with his
behavior and mental thinking. We would rather say that ergonomics forms the principal behind
the MMIs (Cheng, and Zelinsky, 2006). The user experience and their efficiency could be
enhanced with the unique opportunity for learning, creation and knowledge. This could helps
user to gain high acquisition skills over HMI. A high realistic Man-machine interface could be
able to interact with the external equipments and could provide realistic data from those
interactions (Sawaragi, 2009).
The major advantages of using HMI are as follows:
 Reduces the error made by the human that could be detected easily
 Maximizes the user and the systems efficiency
 Increases the comfort of the users and enhances the user acceptance
 Task saturation could be reduced abundantly
 Highly reliable and could be maintained easily
 Maximizes the productivity and growth in the economy that could yield high profit
Traditional Human Machine Interface:
When the user is necessary to be present in the operating place then it could be termed as local
or traditional HMI (Feddema, Keller, and Howe, 2007). The action performed by the user could
be of various forms such as pushing the buttons on or off, interaction with the touch screen,

switching over the process variable etc. This process obviously brings certain problem although
it has certain positive factors. These cons are as follows:
 First and foremost, a person has to physically stay over the place. If he had to switch
places and got delayed in operating certain functions then there occurs huge problem.
In other sense, if the machine is in the remote location or in some other place and in
case of any emergency situation if the person is not present then there occurs huge
problem.
 Secondly, it is hectic to manage the technical side of things (Friedrich et al, 2009). With
the traditional HMIs the updates has to be carried out by certain individuals and it could
take huge amount of time. If these software updates are really and taking a large
amount of time then these issues could be a pain that could need an individual to
update all and restart a system.
Web-based Human Machine Interface:
Web-based HMIs are the recent trend that has been going on in all the process industries. This
HMI could have an access through the web, which means that any device could be connected
once they gain their access through the internet. These HMIs forms a great solution to the
traditional HMI and we do not need any human intervention (Graves and Czarnecki, 2007).
User could be able to monitor and control the devices from the remote location. It is not
necessary for the user to be physically present. With the rising use of mobile application this
could be made easier with the go on process and get the notifications by hand.
Since these HMIs rely on the internet access the updates could be done automatically and
ensure the system to be using the latest notifications. This is the most expedient way of
approach. Once the user logs in the application it could send the most recent updates for the
users, relevant of accessing the usual webpage.
One of the major problems that occur in these HMIs is the security issues. Privacy is the
greatest threat for the internet based application. A proper connection should be maintained
among the components of the HMI connection in order to enhance the reliability. A hacker
could attempt to gain access over the component and change the configuration that could
interrupt all other system connected to it (Bajcsy et al, 2007). This is extensively done in DoS
since hacking the server could interrupt all other nodes connected to it. During the protocol
development it is necessary for the protocol designers to pay attention to this threat.

Multiple organizations are involved in this design for the effective operation of the HMI
systems. An issue known as federated identity management occurs, which needs the access
from the remote organization for the multiple components involved in the HMI since several
equipments needs certain authorization ( person or equipments involves in getting permission
from other entities). This issues could be solved by Security Assertion Markup Language (SAML),
Web Services Trust (WS-Trust), and PKI (Iwakura, Shiraishi, Natkauchi, and Anzai, 2009). It is
necessary to have interoperability, since no conflicts should happen among the involved
organizations.
This web based HMI is not required in every field. Sometimes, local HMIs could pay a severe
attention where there is a necessity of a person to be physically present in that environment.
Each organization should finely balance the needs. If we opt to gain mobility, ease convenience
and monitoring then we should only use the web based application. Otherwise the traditional
HMIs are the best.
Display System:
The display system should have the following properties that are as follows:
 The data could be sustained by gathering the information from the operator and gets
stored in the short term memory
 The whole information could be processed as a bunch at a single time.
 It is necessary to group the data into a single group since the short term memory could
store seven items with plus or minus 2 items.
 It is necessary to be consistent
 If we have three specific values in a vessel that relates them then display it inside the
vessel since it permits the operator to view them as a bunch of data. When they are
placed outside the vessel then the operator could view them as three individual parts of
data (Hamada and Luo, 2001).
Analog and Digital Display system:
Most of the devices such as amplifiers, regulators, converters etc, deal with the signal
amplification. In analog system, the circuits amplify the weak signals, which are known as the
pre-processing. The signals that are obtained in the real time are in the form of analog pattern.
The analog signals could notify us the signals that are in the minimum range.
Digital system could help us in storing the data for the later reference. They work with the fixed
logic of 0 and 1. They do not essentially work with amplification. Moreover, analog systems are
extremely slow when compared to the digital circuits that form a great difference. Presently,
every system is digitized to get the higher processing speed advantage (Jagersand, and Nelson,

2010). For instance, filters that we require in the electronic equipments are in the form of both
analog and digital.
Benefits of the digital systems are as follows:
 They could be easily programmed
 Hardware cost could be highly reduced
 Faster in response and has a high processing speed
 Highly reliable
 The results could be obtained very easily
Pictorial and Text displays:
In the field of automation, a good HMI display is utmost an important device.Presently we have
visual displays in all modern equipment that are designed in a way to fulfill a particular range of
requirements. This could provide a large efficiency with the minimum human errors. In order to
design the HMI monitoring system with the multiple visual display system certain factors should
be considered: 1) the screen must be able to handle with the maximum clarity display 2) the
operator should be able to handle the system though he is having a minimum experience.
Screen Layout:
A good HMI display system should have the proper screen layout. A HMI screen is generally
scanned by the human operator from the left to the right corner and then to the lower corner
that is exactly similar to the typical screen. Important objects should be placed in the area
where the operator could view it very easily. Alarm should be placed at the page top side
(Bourhis, and Agostini, 2013). Left side could consist of any graphical data and the center right
could have the key data. Lower left side should be composed of the start and the stop control,
whereas the lower right side should be composed of the navigation controls. These objects
should be necessarily highlighted with the black outlines.
Background colors:
For the background, it is necessary to use the pastel colours such as light brown, grey etc that
could be a perfect contrast for the dark and the light screens (Brutzman, 2011). Moreover, it is
not recommended to use the primary colours such as green, red and blue as the background
colours. Although, black and white makes a perfect contrast colours it might be invisible in the
dark or in the light screens. When a display is composed of numerous pages, multiple shadows
could be used for each page that makes easier for the operator to identify the pages at a single
glance from the distance sight (Rodriguez, Codourey and Pappas, 2014).

Object Display colours:
For certain operators certain colours have been used that are default in a HMI or DCS design
standard. They are as follows:
 Red is used in case of emergency situation or stop or prohibition
 Green indicates the start or the safe situation
 Yellow indicates the warning instances
 Blue indicates the operation that is necessarily or sufficiently carried out
These colour notations should be clearly viewed by the operators according to the HMI
standard and these above mentioned colours should not be used for any other purposes since it
could lead to any misunderstanding and it could lead to confusion for the operator (Backes,
2008). Dark colours are not suitable for larger blocks since they could produce complementary
colour image retention on the retina. The colour selection for the HMI system is shown in the
figure given below.
Figure 1: A Bad HMI colour selection Figure 2: A good HMI colour selection
Link: (figure 1) https://www.google.com/url?
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Link (figure 2): https://www.google.com/url?
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Picture and Graphics Issues:
The general usage of graphics does not work when it comes to a good HMI design. The design
should be perfect rather than fancy. They don't have any fancy animated lights or bright
colours, moving and spinning pups and conveyors (Bourhis and Agostini, 2010). HMI graphics
are preferred to have a grey background. In order to avoid the operator getting detracted from
the dynamically changing data, cross lines with animated images should be avoided. Complete
HMI process should be necessarily bought in a single screen. This could enable the operator to
detect the operation of the complete process of the plant (Chen and Hwang, 2006). A good
HMI should have the process flow indicated in black colour. The comparison of good and poor
quality graphics has been shown in the figure given below
Figure 3: Poor quality graphics HMI Figure 4: Good quality graphics HMI
Link: https://www.google.com/url?
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Text Display:
The information from the HMI could be conveyed easily by displaying the text in the HMI
screen. The font and the colour of the text should be chosen in such a way that the operator
should not face any difficulty while reading it. Fonts such as Times New Roman, Arial etc could
be chosen that are commonly available in the computers. The text should necessarily be in
black and the user should be able to read the information from anywhere. Heading and labels
text should be larger when compared to the text displayed foe the alarms as well as the buttons
(Bourhis and Agostini, 2008). But the text variations should be limited. Uppercase and underline
text could also be used that could avoid strain for the eyes.
Alarms and Event:
Alarms plays a major role in the MMI equipment since it could inform the operator in case of
any critical situation that could occur in the plant during any process. Any changes in the
process could be notified by the alarm system and it is necessarily recorded. Alarm is composed
of certain design pattern that has the following characteristics:
1) Informative: It is not necessary to take any action, e.g. the process stops at 10.00 AM
2) Warning: The process could have some trouble or it could get severe damage, e.g. any
orientation problem with the bottles.
3) Blocking: In order to protect the device from any risky operations, the controller blocks the
other functioning until the reason for its occurrence is cleared.
Factors that Contributes to choose HMI:
Operating Environment: This could include certain hazardous environment where the humans
could not be allowed. Any unusual environment could narrow the selection of HMI. For
instance, it is necessary to have rugged equipment while the ambient is filled with extreme
noise and vibration.
Based on the application: There are 2 broad categories that help in choosing the right HMI
 Push button replacer: Before push buttons and LED has been in operation to indicate
the status and condition of the system (Kheddar, and Coiffet, 2000). Now we could use
the HMI emulating buttons and switches, which replace the wired inputs and outputs.
 Data handler: This includes certain alarm circuits for performing certain functions such
as trending data, logging data etc. HMI could handle all these function in a 6 inch screen
by displaying it in the form of graphs

Appropriate Connections: A combination of several components forms a HMI. Hence the
components should have the facility to get connected with the HMI equipment.
Programming Software: Hardware components once placed should be able to collect data and
display them, which could be possible by setting up the software (Myung , Cannon, Freivalds
and Thomas, 2008). Bosch Rexroth, for example, has its VI-Composer. Proprietary software
tends to be simple to use and allows for quicker development times.
Conclusion:
HMI system has highly reduced the effort of human. In some cases we need the operator to be
present in the environment. But it could make the entire situation easy for them to monitor.
The best examples for the HMI include the touch screens and the membrane switches. Those
technologies could be widely expanded to the pattern recognition, flat displays, personal access
and the internet and to the other electronic equipments with the fusion of information. The
guidelines could be provided by the GEIA and ISO that offers certain standards for the
Computer and human interfaces.
References:
Operator Screen (HMI) Design Guidelines Retrieved from www.hexatec.com
Anderson, R. J. and Davies, B., (2010). Using virtual objects to aid underground storage tank
teleoperation. Sandia National Labs. Albuquerque, NM.
Backes, P. G., (2008). JPL Space Station Telerobotic Engineering Prototype Development:
Advanced Telerobotics System Technology. Jet Propulsion Lab, Pasadena, CA.
Bajcsy, R. Enciso, R. Kamberova, G. Nocera, L., and Sara, R. (2007) 3D reconstruction of
environments for virtual collaboration. Princeton, NJ, USA.
Bourhis, G. and Agostini, Y. (2010). Task sharing and trading for an intelligence powered
wheelchair: problematics. Symposium on Robotics and Cybernetics. CESA '96 IMACS
Multiconference. Computational Engineering in Systems Applications.
Bourhis, G. and Agostini, Y.(2008). The Vahm robotized wheelchair: system architecture and
human-machine interaction. Journal of Intelligent and Robotic Systems: Theory and Applications
. 22(1):39-50.
Bourhis, G. and Agostini, Y.,(2013). Man-machine cooperation for the control of an intelligent
powered wheelchair. Journal of Intelligent and Robotic Systems: Theory and Applications . 22(3-
4):269-87.

Brutzman, D. (2011). Virtual world visualization for an autonomous underwater vehicle.
Challenges of Our Changing Global Environment. Conference Proceedings. CA, USA.
Chen, P. C. and Hwang, Y. K.(2006). Generating natural-language like robot motion command
set through machine learning. Proc IEEE Int Conf Syst Man Cybern, IEEE. Piscataway, NJ, (USA).
vol. 1pp. 114-119.
Cheng, G. and Zelinsky, A.(2006). Supervised autonomy: a paradigm for teleoperating mobile
robots. IEEE/RSJ International Conference on Intelligent Robot and Systems. Innovative Robotics
for Real-World Applications.
Feddema, J. T., Keller, C. G., and Howe, R. T. (2007). Experiments in micromanipulation and
CAD-driven microassembly. Proceedings of the SPIE - The International Society for Optical
Engineering . 22(1):2-4.
Friedrich, H., Muench, S., Dillmann, R., Bocionek, S., and Sassin, M. (2009). Robot programming
by demonstration (RPD): supporting the induction by human interaction. Machine Learning
[MACH LEARN], Vol. 23, No. 2-3, Pp. 163- 189.
Graves, A. R. and Czarnecki, C. (2007). Distributed generic control for multiple types of
telerobot. International Conference on Robotics and Automation. Detroit, MI, USA.
Hamada, T. and Luo, R. C. (2001). Gesture recognition using syntactical hand-sign parsing. 22nd
International Conference on Industrial Electronics, Control, and Instrumentation. Taipei, Taiwan.
Iwakura, Y., Shiraishi, Y., Natkauchi, Y., and Anzai, Y. (2009). Realworld oriented distributed
human interface system that adapts to uncertainty of user's activities. Transactions of the
Information Processing Society of Japan . 39(5):1502-13.
Jagersand, M. and Nelson, R. (2010). Visual space task specification, planning and control. Proc
IEEE Int Conf Comput Vision, IEEE, Piscataway, NJ, (USA). Pp. 521-526.
Kheddar, A. and Coiffet, P. (2000). Navigation in virtual environments: head behavior based
control applications to VR based robotics. 4th IEEE International Workshop on Robot and
Human Communication, Tokyo, Japan.
Myung H. Y., Cannon, D., Freivalds, A., and Thomas, G. (2008). An instrumented glove for grasp
specification in virtual-reality-based point-and-direct telerobotics. IEEE Transactions on
Systems, Man and Cybernetics. 27(5):835-46.
Rodriguez, M., Codourey, A., and Pappas, I. (2014). Field experiences on the implementation of
a graphical user interface in microrobotics. Proceedings of the SPIE - The International Society
for Optical Engineering .

Sawaragi, T. (2009). Design of human-artifacts symbiotic systems under resourceboundedness.
Journal of Japanese Society for Artificial Intelligence . 13(3):371-8.