The term “Human Machine Interface” implies all range of control panels that are used almost everywhere – from simple record players to a plane cabins. Human machine interface systems exercise control over processes, monitor working states of factory facilities and guarantee work productivity and efficiency.
With increasing possibilities of the PC’s, hardware and the software, HMI developers started to pay greater attention to the fact how people interact with computers and try to establish best human machine interface (HMI) solutions in order to get a product that will be both simple and handy for engineers.
Designers and developers use those HMI solutions which can provide clear and consistent “system-operator” communication and real-time feedback. Years of research in the field of ergonomics and human behavior have resulted in large volumes of information about HMI development we have now.
In this article, we will look at the most important aspects of human machine interface development, and also will give some tips for those who are thinking about developing a custom HMI product.
Basic principles of HMI development
The basic and most important principle by which HMI developers are guided is that: the person who will control system through the HMI need to be well-versed about system’s current state. So we need to implement this principle along the developing an HMI product: to give a person not only an information about system’s current state but also make it possible to “predict” any changes which can occur in the system. Here are some tips on how to increase user awareness of the situation and system state.
1. For HMI build working structure that corresponds to a mental model of a user.
What does this mean? it means that user understanding of how the system works should correspond to the sequence of processes in the interface. Without the exact model of thinking, the operator can incorrectly interpret an information he receives from HMI. He won’t understand assignment of changes in system or results of the actions or events in system.
Therefore before HMI development we need to do a research and work in close cooperation with users (HMI operators) to understand their models of thinking. At the same time, we need to be careful and not to make radical changes.
2. For HMI development select only important data.
The first step is to understand, what information is the most important for implementation, and what less. Think, what are the tasks of the person who will deal with the HMI. According to this research define the relative importance of data in normal and abnormal situations that can occur.
3. Show trends in HMI system.
Trend lines show us what’s going to happen next. They help operators to "predict the future". Trends allow us to see, whether a system is moving in the right direction or not and where particular actions might lead a system.
Also, on the basis of trend lines, it is possible to monitor the hardware with a view to identifying possible problems and facility failure. Trends are important because they allow us to take measures before a certain process evolves the wrong way.
4. Always provide borders for user’s actions.
Let's assume, you drive your car on the wide highway which has beam sensors on the each side instead of lanes marking. And each time your car crosses the beam car user interface says you drive wrong way. Well, to move from side to side each time you cross the line is quite an intense process.
Think, how much fuel do you waste, moving that way, from side to side? Wouldn’t it just be simpler to drive in a straight line? It is more convenient to know that you are in the middle of the road and the only thing you need to monitor is that you are still there. This example illustrates how the HMI ideas are implemented in automotive user interfaces of cars. The same can be said about other industries – user need to know that there are some define borders, so he would work within them only.
In such case, sources of information can be different scheme combinations, the existing screens, technological processes, etc. Human machine interface tools provide the reading of information from such devices as current sensors, temperature measuring instruments, etc. As for the most advanced HMI systems, they have an opportunity to work with video cameras, microphones and loudspeaker systems, can connect to corporate networks, for example, for reports printing on the remote printers.
Visualization in HMI systems
In general, the main goal of visualization is to decrease user’s brain load. The interface should be simple so the user can easily understand all occasions and effectively react to them. The user has to understand well the HMI screen, consider the priority of each task and select information that is necessary at the moment. The clear, well organized and ordered information helps the user to react to alarm signals quicker and understand the whole process better. The main stages of visualization process in HMI niche are:
Usually, information about any changes of operating conditions is displayed on the screens of HMI. In the case of a disruptive event, the user needs to have an opportunity to identify an event under any external conditions as soon as possible. For drawing user’s attention various practices can be used: screen blinking, color changing, sound signals etc.
To prevent any actions which could threaten safety, information which is seen by the user has to be rather accurate and exact to provide possibility of its immediate understanding. The ergonomics of dialogue interface components is important, just like their functionality.
Depending on what message is sent to the operator by the system, the user might need to act quickly, pressing one or several buttons or keys. In this case, the correctness of the specified actions is provided by "clever" ergonomics, large icons on the screen, etc.
Development of the HMI screens
While operating, HMI system allows to control process of production and to manage it. For these purposes, special function keys, switches, and popup windows are usually used in HMI. For a touch screen, special areas of it can be assigned for commands entries. Development of the HMI screens differs little from creation of the text document or presentation. It’s simply necessary to follow basic rules:
1. Create and define standards for the screens
Consider an environment, for example, lighting, a number of controlled screens and approximate distance from eyes to monitors. These factors can help to determine standard type sizes, a type of characters on the screen and their color. The library of forms and pictures can help to provide coherence of necessary images.
2. Delete superfluous data
Group, but do not create a heap of the functions and service reports. Construct hierarchy of information where you can easily move. Be sure to check that all the interconnected information is visually grouped. Evenly positioned information will reduce a disorder. Also, pay attention to the fact that it is easier to read diagrams and charts if the main task/function is located in the center of the screen. Apply this logic to HMI indication screen.
Information coding on the display allows the operator to check effectively dozens of parameters within several seconds. It allows to control processes and provides early detection of deviations. There is no need to wait until the alarm system will tell us about a problem.
So as you see, development of the HMI screen means such simplification of the process at which the operator can easily see all the events of one certain section. Before developing the screen, consult with the users – this is the best source of information for the development of the HMI screen.
Modern processes become more and more complicated and more and more serious requirements are imposed to the functionality of the enterprises’ facilities, vehicle user interfaces, etc. The user needs to have the most accurate picture of all events. That is why the main task of human machine interface is to provide the highest possible transparency and data accuracy level.
Also remember, if you want to get a product of the highest quality, the only way to do that is to hire a team of professionals. Our company always give such IT-solutions that give our clients the edge over competitors. Contact us and you will get all additional information about HMI development you are interested in, it’s possible terms and costs. firstname.lastname@example.org