The use of science and technology principles in the medical field of rehabilitation is done to improve the health of those who have disabilities. The design and creation of tools or devices that improve the condition of those with disabilities are covered by the field of rehabilitation engineering.

Rehabilitation engineering is totally design oriented. The creative process in which the needs of the particular disabled person are thoroughly studied and devising an assistive device to meet those needs is the main objective of rehabilitation engineering.

Design process:

There are five main elements of the design process. They are,

  • Analysis
  • Synthesis
  • Evaluation
  • Decision
  • Implementation


The process of thoroughly investigating the problem before arriving at a particular solution is called analysis. The endpoint of analysis is the creation of a list of operational features regarding the solution. The specifications of the solution’s performance must also be listed.


Synthesis is a creative activity in which a list of possible solutions is made after a deeper understanding of the problem has arrived. This process is guided by the learned engineering principles, handbooks, design magazines, catalogs, and consultation with other professionals.


The testing of the proposed solution/design through field trials with computer simulations, mock-ups, mechanical drawings, etc is known as evaluation. This is done by considering the end users and the stakeholders of the particular problem. The experimental results should be carefully recorded for later review. The quantitative comparison chart is one of the very useful methods in the process of evaluation.


The final decision is taken based on the preference of the user according to principle 5 of assistive technology. While arriving at a particular solution for the problem, consulting a person who had encountered a similar situation is also done.


The fabrication and installation of the final solution for the disabled person is known as implementation. This requires additional project planning depending on the size of the project. A simple list of tasks to a complex set of scheduled activities involving many people with different skills are involved.

Key ergonomic principles of rehabilitation

Another crucial component of the design of assistive technology and rehabilitation engineering is ergonomics, or human factors. When creating assistive technology, it is important to take human behavior, capabilities, limitations, and other characteristics into account when building tools, adaptations, electronic devices, tasks, and interfaces. Lets take a look at the key ergonomic principles to be followed during the design of an assistive device.

Principle of Proper Positioning:

An individual who has lost the capacity to maintain a stable posture against may appear to have more abnormalities and functional impairments than are actually there without the right 
positioning or assistance. The rehabilitation engineer must make sure that no matter what
modification or assistive technology is being designed, the person’s trunk, lower back, legs, and arms will always have the required stability and support.

Principle of the Anatomical Control Site:

Since assistive technologies rely on the users to send command signals, users must be able to clearly express their intentions. Any body part that the user has control over in terms of speed and dependability can serve as the anatomical control site This can be achieved by a range of switches and sensors that are accessible. After selecting the best site, a suitable interface is created for it.

Principle of Simplicity and Intuitive Operation:

Intuitively simple operation is the ultimate goal of equipment design, which is particularly true for electronic and computer-based devices. The right selection of compatible and optimal controls and displays is essential for intuitively effortless operation. The learning rate, reaction time, chance of error, and user happiness increase when compatibility relationships between the user and the assistive device are taken into account.

Principle of Display Suitability:

The choice of the display is sometimes decided when choosing or designing displays for the transmission of information, such as when designing a warning signal for a person who is visually impaired. However, the rehabilitation engineer must use the key advantages of one sensory modality over another when it is possible to do so for the sort of message or information to be delivered.

Principle of Allowance for Recovery from Errors:

Both human factors or ergonomics and rehabilitation engineering aim to provide assistive technologies that will increase a person’s skills while reducing errors. Nevertheless, no matter how carefully something is planned, human mistake is unavoidable. As a result, the assistive technology must offer some kind of mistake tolerance without substantially affecting system functionality or safety.

Principle of Adaptability and Flexibility:

One essential principle of ergonomics is that devices should be made to fit the user, not the other way around. An assistive device’s operational qualities must vary as conditions change and/or the user develops greater proficiency and ability in using it. The process of selection and feedback should also be adaptable.

Principle of Mental and Chronological Age Appropriateness:

Congenital disability patients typically have a smaller range, diversity, and amount of life experiences. Because of this, their behaviors and emotions frequently resemble those of a much younger person. Therefore, the rehabilitation engineer should determine the functional age of the person who needs assistance during evaluation and problem definition. Direct observation, as well as interviews with family members, teachers, and social workers, are all effective ways to acquire behavioral and biographical data.

Thus the design process of a particular solution and the key ergonomic principles impacting it were discussed in detail.

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