Qualitative Prototyping as a Process of Innovation for Ambulatory Assistive Devices

Bjarki Hallgrimsson, MSE
Assistant Professor, School of Industrial Design
Carleton University, Ottawa, Ontario, Canada


This paper is of particular relevance to ambulatory assistive device manufacturers as it describes an approach to the product development process that places additional focus on the end user and innovation. The examples focus in particular on rollators, but apply equally to other devices in the field. Whereas quantitative prototyping is used to test and validate a new product, qualitative prototyping is used to envision and explore new ideas, often prior to writing specifications for new products. Qualitative prototyping should encompass a human centered approach to ideation and examples of specific features developed for rollators using this approach have been included.


Qualitative prototyping, ambulatory assistive device, rollator, product development, innovation


As the North American older age demographic continues to grow, so does the market for products for independent living. Ambulatory assistive devices such as rolling walkers or rollators, allow older people with physical support needs to maintain a healthier and more independent lifestyle. These products are used in the home as well as outdoors and usually collapse for travel. Since they become part of  people’s lives, even small convenience features can therefore have a marked impact on user satisfaction and acceptability.

The competitive nature of this market has also created the benefit to the consumer in lowering of prices. From a manufacturers point of view, this has created the pressure to become more innovative so as not to compete on price alone. Innovative new features in turn add extra benefits for the end customer.

Innovation can be classified as either incremental or fundamental. The former tends to focus on technical aspects such as improving the product quality or lowering the cost of production. The latter tends to focus on solving previously unaddressed user needs beyond mere technical functionality. Bringzén and Biel-Sanchis noted how rollators, although providing high quality function, often take on a machine like quality. User acceptability can therefore be increased by a more human focus (1).

Fundamental innovation requires spending more time researching user needs up front. This paper outlines the importance of early prototyping as a means for investigating new ideas through user centered research. Early quick prototypes typically lead to better insights and allow the development team to investigate different usability aspects early on in the project. This in turn allows the company to evaluate project feasibility and to develop better end user specifications for new product. Thomke describes “front loaded development”, where emphasis is placed on the process of innovation through experimentation and early prototyping (2).

The benefit of prototyping is well known in the technical context of product verification, testing and certification; it is less understood as a tool for developing and nurturing new ideas through experimentation. The fundamental difference is that prototyping early on in a project has the potential to influence and to create a set of product specifications, whereas in the later stages of product development it is mostly used to validate and test the product against already established specifications. It is therefore important that companies do more early prototyping, so that they can benefit from the experimental investigate attributes of such prototypes.

Kelley describes the importance of three R’s in early prototyping as “rapid”, “rough” and “right”. The point being that it is sometimes extremely simple mockups and models which can be made quickly to verify the feasibility of an idea (3). This approach is usually hands on and qualitative.


The traditional simplified model for developing new products is based on developing a technical specification first. This specification may be completely focused on lowering the cost of the product or it may include some new product requirements typically identified by the company. The engineering and design team then develop a design based on these criteria.

This process is linear and is usually limited to incremental innovation as companies tend to focus on improvements rather than fundamental rethinking of their product lines. In order to create breakthrough innovations companies must spend more time up front to investigate the fundamental problems and look for insight into human behavior and need (4).

IDEO is a product development firm based in California that has clearly demonstrated the benefit of qualitative prototyping as a means to help companies become more innovative. The company developed the award winning Diego dissector tool for ear nose and throat surgery. The tool has an innovative forward swept handle, which allows the surgeon to maintain a neutral hand position. The first prototype was envisioned and mocked up in a meeting with physicians by one of the designers, using a marker, film canister and a clothespin. Whereas the final engineering and development took months to accomplish, this quick model allowed the team to evaluate the innovative aspect and feasibility of the approach immediately (5). This innovative approach can and has been used by peer designers in the ambulatory assistive device market.


The following steps form part of an early qualitative prototype process, which in turn is a practical complement to quantitative research and development. These are important in establishing user acceptability and allow for parallel idea evaluation and feedback.

Image shows an elderly person with a rollator opening the door to a bathroom and turning around so as to walk backwards into the bathroom with the rollator. Photo 1: Problem Scenario Prototype (Click for larger view)

The starting point for a new product is to work through problem scenarios rather than to establish specifications for the product too early. In order to develop these scenarios, designers often use video to document and observe people using existing products. Upon analyzing the footage, researchers sometimes uncover insights that not even the end user was completely aware of. Insights about problems are also obtained by surveys or discussions with specialists, such as occupational therapists as well as end users. The problem scenarios can be prototyped as storyboards, which are disseminated to the product development team of people as a starting point for ideation. A scenario prototype is shown below and illustrates the use cycle of going to the bathroom with a rollator. Most homes have smaller bathrooms and thus force the user to turn around and walk in backwards in order to maneuver into the tight space.

Image shows a rollator with a reversible back-strap and an elderly person sitting on the rollator Photo 2:  Reversible Backstrap (Click for larger view)

The infinity 500 Rollator made by  Dana-Douglas Inc., has an interesting feature which allows users to sit facing either forward or backward at a dining table (6). The innovation originated by observing how people would park their rollators next to their dining tables, as opposed to simply sitting on their rollators instead. The problem was prototyped in the form of a problem scenario, which showed that it was hard to back in towards the table, lock the brakes and consequently turn around and sit down. If the product had a reversible back-strap which could simply be flipped around, then several of these steps would not be necessary. A crude simple mockup was made by cutting an existing back strap and allowing it to pivot with a couple of screws. The benefit of this idea could be verified immediately and led to further development as well as a distinctly innovative functionality, which was patented by the company.

3D computer aided design (CAD) modeling is an excellent tool for rollator product development. The digital prototypes can be used to evaluate form fit and function. The data can be output directly to rapid prototypes made from various materials including plastics. Information such as total product weight, allows the designers to optimize strength versus weight ratios. Many other factors can be tested and reviewed as the product develops. This type of digital prototyping is invaluable and saves a lot of time in development while increasing accuracy and reliability.

The caution is that digital prototypes still take time to develop. Whereas they are invaluable tools for the profession, it is still important to not rely on them in lieu of physical prototypes. Evaluating a product on the computer screen does not evaluate it in context of the environment of use. CAD can however be used early in the process as long as it follows the notion of the three R’s.

Image shows a quickly made brake mechanism prototype made from bits of plastic and a more advanced computer aided design prototype Photo 3: Early Brake Prototypes (Click for larger view)

The development of a new rollator braking mechanism for Dana Douglas Inc., shows how the above steps and methods can complement each other. Qualitative user observations and interviews with physiotherapists highlighted the problem with braking cables getting caught on doorknobs. One idea for an internal brake mechanism was discussed in an early design meeting and a crude model was made from pieces of scrap plastic and metal found in the prototype shop. The model was presented to the development team the following day and formed the basis for subsequent development. The photo below shows the simple mockup that formed the basis for the mechanism, as well as the next prototype developed in 3D CAD.


Front loaded development is used to develop new innovative features for ambulatory assistive devices. This starts with observing people and progresses into an experimental process that precedes actual product specifications. Different types of qualitative early prototypes include problem scenarios and simple mockups.  This approach has been shown through examples to be valuable in developing new features. These types of early prototypes are based on observations of human needs and requirements and allow for quick experimentation to ascertain feasibility.

This process does not remove or replace the systematic quantitative testing which needs to happen on any new product development effort. Nor does it replace important quantitative experimental research. It does however open up the initial ideation process, critical to innovative thinking. The process is useful as a method for research and development of new ambulatory assistive devices and may be adopted by manufacturers.


This qualitative prototyping approach is currently being applied to the Carleton University Smart Rollator Project. The interdisciplinary project between Computer Systems Engineering and the School of Industrial Design, aims to study rollator usage in the context of smart sensor technology. Currently students in the School of Industrial Design are studying and observing users at health care facilities, such as Elizabeth Bruyere Health Centre for the elderly, in Ottawa. Based on this research they are developing unique problem scenarios, which we hope to develop into innovative features next calendar year.


  1. Bringzén, K. Biel Sanchis, C. (2007). Design of a Mobile Support for Physically Challenged People, Adapted to Home. 13th International Conference on Thinking, Linkoping Electronic Conference Proceedings, Linkoping, Sweden. Retreived on January 13, 2008 http://www.ep.liu.se/ecp/021/vol1/003/ecp2107003.pdf
  2. Thomke, S. (2001). Enlightened Experimentation: The New Imperative for Innovation. Harvard Business Review on Innovation. Boston: Harvard Business School Publishing, 179-205.
  3. Kelley, T. (2001). The Art of Innovation. New York, NY: Doubleday Books.
  4. Cagan, V. and Vogel, C.M. (2002). Creating Breakthrough Products. New Jersey: Prentice-Hall.
  5. Burroughs, A. and IDEO , retrieved on January 10, 2008 http://www.ideo.com/case_studies/gyrus/
  6. Haller, L. Dangel Cullen, C. and IDSA. (2004), Infiniti 500 Rollator, in Design Secrets: Products 2: 50 Real Life Projects Uncovered, Gloucester, Massachusetts: Rockport Publishers Inc. 198-201.


Picture 1 was illustrated by Justin Frappier, 4th year student in Industrial Design at Carleton University, Ottawa, Canada

Picture 2 was provided by Dana Douglas Inc. of  Ottawa, Ontario, Canada


Bjarki Hallgrimsson, MSE, School of Industrial Design, Carleton University, Ottawa, Ontario, Canada K1S 5B6, Office Phone (613) 520 5677 Email: bjarki_hallgrimsson@carleton.ca