Human factor engineering in the development of complex systems

Yakir Yaniv

Human factor engineering

The man-system integration approach

Integration of human factor engineering in the development of complex systems may be challenging. For this reason, this issue is often not part of the development process routine. This applies to small and large, well-established companies alike.

When human factors are not integrated in the development process, users may end up having to “fight” inefficient procedures to operate the system successfully.

In many cases, the effect may prove to be a combination of problems and have economic implications, such as:

  • Lengthy unproductive downtime
  • Long operator training
  • High chances of human error
  • Complicated, inaccessible maintenance
  • Exposure to ergonomic hazards
  • Frustrated, poorly motivated workers

These effects lead companies to look for methods for integrating human factors in their development processes. However, this is compounded by a concern for longer development time, clumsier processes and longer total project time.

The human system integration approach

This approach addresses these concerns by adopting a systemic view of all points of contact between humans and the product or system.

A good, effective approach takes into account, in addition to design and planning processes, the way in which the organization can adopt and recognize the contribution of an additional discipline too. The understanding of the importance of operational, efficiency and maintainability aspects in addition to technical aspects such as system performance and reliability, results in the development of systems that are convenient to use and a reduction in possible errors during their operation.

In order for an organization that is developing complex systems to enjoy the advantages of human factor engineering in the products that it is developing, it has to adopt an approach of human-centered design as part of its development processes. This approach may be challenging, particularly in large organizations that involve many planning and support terms throughout the product lifetime.

Sometimes it is difficult to accept the idea of adopting a new perspective compared to the traditional way in which things are done.

This does not mean that there is a problem or shortcoming in understanding customers but incorporating human factor engineering and man-system integration helps in performing the correct actions in the correct order and to the scope appropriate for each project.


The complex system challenge

Although the methodology described here can suit and support projects of varying sizes and scales, it is particularly relevant to large, complex systems. A complex system refers to a system that contains a relatively large number of subsystems. The term also refers to the system’s expected complexity of operation and maintenance and the degree of complexity of developing such a system and all its components and development teams, from the stage of defining the requirements to final tests for operation by customers.

Such systems may be industrial machines, medical equipment, defense products and various types of vehicles. The function of human factor engineer is to find humans’ contact points with the system and simplify them for users who come into contact with the system.
The challenges in such activity may be:

  • How to ensure that despite a system being complex, it will not be complex to operate.
  • How to reduce and prevent operation errors.
  • Whether the system may be maintained by its operators.
  • How to reduce ergonomic hazards.

Presentation of human factor engineering as a discipline that must be considered may make the misimpression of complicating the development process instead of simplifying it, so combining the principles in the system engineering process is the right way to go about.

Systems engineering

A good approach to effective incorporation is joint system engineering and human factor engineering work. System engineering looks at the product as a whole system that is supposed to function actively to perform its intended purpose. The system engineer ensures that all subsystems work in unison and according to the requirements defined in order to achieve its intended performance.

Including people who come into contact with the system from the first stage helps in mapping the requirements of the system and subsystems that are related to the users. Using the known tool of requirement management to manage the human factor engineering requirements too is very effective and allows for tracking and fulfilling them in the process. Another starting point is including human factor engineering requirements as part of the system requirements.

Three principles

Although requirements management is an important tool for deployment, a broader approach may help achieve the goals. Human factor engineering is a discipline in and of itself, which is performed by experts in these fields. The issue must be shown to the system designers in the various fields – mechanical engineering, software, electronics, etc. They must be aware of the effect that their work has on the users’ interfaces with the system.

There are three principles that may help focus the effort for successful adoption and that may form a better basis for this work:

  1. Awareness – the engineers and developers need to be familiar with the meaning of human factors. The way in which they wield influence to achieve business objectives, the effect that they have on user safety and the importance that the management attributes to the field.
  2. Training – after awareness has been achieved, brief instructing on the principles of human factor engineering may be meaningful for the way in which engineers understand their role in influencing user experience. They understand the importance of early, continuing implementation until final tests are performed.
  3. Toolbox – by providing engineers tools for human factor-oriented design and selection, the development process may be optimized. These tools may include checklists, data tables and guidelines on the way to choose parts and procedures through the planners themselves. This must include guidelines on the cases in which a human factor engineer must be involved in the design analysis.


The process

May-system integration supports the system engineering from the beginning of the project. There are relevant steps that are important to take in every stage of the engineering process. Just as system performance is defined as one of the first requirements, it is also important to define the expectations of the people who will operate the system at this stage.

Unique steps

A few of the unique steps in man-system integration that must be done at the appropriate development stage follow:

User research- when the target market is defined for a new system, this is also the right time to define who the users will be. This activity should include anyone who comes into contact with the system:

The operators: the main users of the system.

The maintainers: who not only encounter the operation interface of the system but are also required to cope with failures, malfunctions and parts that have to be replaced.

In medical systems, there are patients too: usually they are passive users, but they have physical contact with the system and are sometimes instructed by the equipment operator.

User research is essential for understanding their abilities and limitations. This is also part of the building of the planning intent, such as the degree of skill and training expected of future operators.

Defining the requirements of human factor engineer – through the insights arising from user research, analysis of the system’s expected performance and a review of relevant standards, a human factor engineer should define system requirements that apply to users and the system’s interface with them.
These requirements, like all system requirements, are part of the characterization of the system and the subsystems, meaning that they are reviewed and tracked throughout the development process.

Serviceability tests – are an important tool for incorporating human factors, in which the system’s use is examined, rather than its technical performance. These tests may be performed at any stage of the project. It is important to identify the points in the process in which the contribution of the test results to the product will be meaningful. Mockup models are very useful for trying out different concepts at the beginning of the way; prototypes with limited operability or even the use of the real system is good for use in advanced stages.

The importance of these tests is that they help avoid advancing with insufficient or incorrect design, through mapping of possible usage errors and actions that users would find difficult to perform.

In conclusion, the adoption of human factors in complex systems requires a holistic, comprehensive approach. The system and the interface considerations in the system should be taken into account. An effective way of successful incorporation is integrating human factor engineering into the systems engineering process as a process spanning the system.

It is important to remember that significant adoption may also include organizational challenges, in addition to technical ones, and all the challenges should be considered in a manner that will allow them to be coped with in order to ensure a successful development process.

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