Creating Assistive Technology

Reprinted from PN/Paraplegia News May 2013

Development of new technology for people with disabilities is a detailed process that takes a lot of input and work from many different groups.

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Ever wonder how some of the newest technology for people with spinal-cord injuries and other disabilities comes about? It’s a detailed process that takes a lot of input and work from many different groups.

A traditional product design process includes the identification of user needs, design specification, concept development, concept selection, system design, prototyping, and testing.

However, when designing assistive technology (AT) devices, many different user groups must be taken into account.

Besides the primary end-users of the device, a number of other groups can be considered secondary end-users. These may include family members and/or friends, caregivers, teachers, social workers, occupational therapists, and medical personnel.

Also, funding agencies that can include healthcare and social services departments and a range of non-governmental organizations are important stakeholders.

Not the Standard Process

The design of AT products should not only follow the standard good design process but also consider the needs for design and satisfy primary users, secondary users, and purchasing organizations.

The PerMMA features a robotic arm that gives users greater independence.

Participatory action design (PAD) is an approach to the design, development, and assessment of technology that places an emphasis on active involvement of the intended users in the design and decision-making process.

The Human Engineering Research Laboratories (HERL) at the University of Pittsburgh has adapted the PAD approach to develop a new participatory design model that will enable it to gather design feedback and guidance from users for all products in the development pipeline. The user participatory design (UPD) framework incorporates the traditional and PAD design processes.

Integrating Users

The process starts with the preproject phase, identifying general and specific application and technology characteristics.

User needs, target population characteristics, and barriers to adoption are identified. During the pre-development phase, user-centered methods such as user observations, storyboarding, rich stimulus displays, and scenario testing are employed.

All the information gathered from these methods is assembled to come up with the conceptual design, and performance objectives from a user’s perspective with measurable outcomes are also developed.

The detail design, component development, design documentation, testing results, etc., are conducted during the user-centered design prototype phase. With the designed prototype, further work continues on functional performance verification, and with refinement the robust prototype is developed.

The performance, failure modes, and usability are tested in a laboratory environment, and technology refinements are completed based on the test results. A full evaluation of the system by prospective end users in the field is completed to make sure the system meets or exceeds performance requirements.

Finally, clinical trials are performed to prove efficacy and safety of the replicated system. At the end, regulatory clearances and engineering for manufacturing are applied for the final commercial product.

HERL applies the UPD framework throughout the entire product development process. The multifaceted dimensions of this framework allow it to integrate users, technology, environment, and economic elements into technology development.

Here is a quick look at three assistive robots being developed following the UPD framework.


The Personal Mobility and Manipulation Appliance (PerMMA) is a wheelchair with robotic arms that can be controlled by the wheelchair user, a remote helper via the Internet, or a combination of both.

PerMMA will offer greater independence to individuals with mobility and upper-extremity impairments by allowing them to perform tasks in their home and in the community that would otherwise require the assistance of others. PerMMA is currently in the robust prototype phase, heading to the laboratory prototype phase.


Mobility Enhancement Robotic Wheelchair (MEBot) is an intelligent robotic wheelchair.

It features a movable central drive wheel that can reposition itself to simulate front-, mid-, or rear-wheel driving, two sets of independently-moving smaller caster wheels, and internal sensing of weight distribution and inertia.

All degrees of freedom are controlled by a custom embedded system and available to the rider through a joystick, switch and keypad interfaces.

MEBot (previously called PerMMA Generation 2) climbs curbs, inches across ice, and tackles other challenging terrain manually or independently. It’s currently in the user-centered design prototype phase, heading to the robust prototype phase.

Strong Arm

Strong Arm is a robotic manipulator that can lift and hold a 250-pound payload and can be mounted on a power wheelchair.

The goal of Strong Arm is to facilitate transfers such as from a wheelchair to a bed. It can also be used to move everyday heavy objects such as a gallon of milk, pot of water or turkey. It’s currently in the user-centered design prototype phase heading to robust prototype.

A Better Approach

By using the UPD framework during the design and development of PerMMA, MEBot, and Strong Arm, HERL has been able to shift users from a more reactive role (where they respond to products via focus groups and field trials) to a more active role, where they are providing guidance during many steps of the design process.

This approach could help refine the quality and usability of assistive technology currently being developed, and help facilitate the product development cycle.

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