DESIGNING A SHORT-RANGE WHEELED MOBILITY DEVICE FOR WOMEN IN INDIA

John T. Lysack, Susan J. Mulholland, Vikram Panchal*, Urs P. Wyss, Tanya L. Packer

Department of Mechanical Engineering, Queen's University, Kingston, ON Canada

School of Rehabilitation Therapy, Queen's University, Kingston, ON Canada *

Faculty of Industrial Design, National Institute of Design, Ahmedabad, India

ABSTRACT

The design of appropriate rehabilitation technology requires the careful consideration of numerous interdependent design parameters. The technical, functional, economic, and cultural environments in which the technology will be used must be well understood and accounted for if a design is to be successful. This paper presents a case study of these issues within the context of rural and low income India, wherein novel 'low-height' mobility devices for disabled women were designed and fabricated. Detailed design analysis from both the cross-cultural and cross-professional perspectives was performed with a major emphasis on user feedback throughout the design process. Using this design philosophy, a path was ultimately negotiated between the ideal and pragmatic dimensions of rehabilitation technology development.

BACKGROUND

"Mobility is critical to the fabric of human society. It is essential for almost all aspects of daily self-care, work and play. Without mobility, the barriers to participation are immense" (1). It is the effort to remove these barriers to participation which has led to the design and development of better mobility devices. Although great technological advances in rehabilitation technology have been realized in the West, these advances are not always easily transferable to developing countries. To account for this difficulty, effort has been spent on developing 'appropriate technology' - technology which considers the economic and cultural environments in which it will be used. Although progress has been achieved, the need remains staggeringly high.

It has been estimated that of the some 20 million potential wheelchair riders in developing countries, less than 1% currently use any such device (2). Specific to India, the need for wheeled mobility devices is thought to be approximately 3-4 million. Furthermore, current estimates of Indian wheelchair production are on the order of only 20,000 units per year (3). Clearly, given the large supply deficit and low domestic production rates, a great need for all types of mobility devices will remain well into the next century.

Logically, different types of mobility devices are appropriate for different activities. The type of device required is a function of the task at hand, the physical distance which must be traversed to perform the task, and the specific functional needs of the user. For example, a hand driven tricycle (a long-range device) would be appropriate for a rider with good upper body strength to travel several kilometres. For shorter distances, a wheelchair (a mid-range device) may prove to be more useful. For activities within and around the home, however, especially in cultures where many activities are traditionally performed on the floor, neither device is appropriate. In these situations, 'caster-carts' or 'floor scooters' are sometimes used. In India, many types of caster-carts are presently being used, especially in urban areas. Hof has stated that, "there is a need for thorough evaluation and dissemination of good caster-cart designs" (4). The authors of this paper concur, and have identified the potential for 'new' designs.

OBJECTIVE

The objective of the project is to design and develop a novel mobility device for use by women in rural and low income India. This device is intended to assist the user in performing activities of daily living within and near the home and to therefore fulfill a need not well satisfied by wheelchairs, tricycles or other existing mobility devices. Specifically, the new device is intended to assist the user in performing those tasks which are traditionally performed at ground level. To this end, the device will most evidently differ from traditional wheelchairs by physically keeping the rider near to the floor. The design concept is based on existing 'caster-carts' and is labeled a 'low-height short-range' mobility device.

The specific objectives of this paper are threefold: (i) to demonstrate the complexity which arises from the numerous interdependent design parameters associated with the design of appropriate technology, (ii) to discuss the design method used to successfully address this complexity, and (iii) to present the results obtained from the short-range mobility device design process.

METHOD

Orpwood suggests that the design of rehabilitation technology involves the consideration of numerous complex biological variables, such as anatomical, physiological and psychological variables (5). To this list could be added the list of technical, functional, economic and cultural variables associated with appropriate technology design. To efficiently address these numerous interdependent parameters as they pertained to the Indian mobility device project, a design methodology adapted from Orpwood was used.

Initially, interest was directed at the layout of the device. Numerous simple sketches were developed showing different conceptual layouts that were possible within the restrictions imposed by technical factors such as anthropometrics and ergonomics, and functional factors such as the required ranges of motion deemed necessary from a task analysis. From these preliminary sketches, a preferred layout was decided upon through collaboration of technical experts (mechanical engineers) and functional experts (occupational and physical therapists). A mock-up (a simple three-dimensional model which emphasizes the proposed geometry) was then constructed based on the preferred layout. To evaluate this first design, a focus group was conducted to obtain critical feedback. The participants in the focus group were chosen for their experience with disability and Indian culture. From this feedback, numerous additional sketches were produced to reflect the latest input. Again from these sketches, a preferred layout was collaboratively obtained. Using this new layout, technical supporting features such as the frame, seating platform, and wheels were designed. A working model was fabricated which incorporated these new design aspects. This working model was then used as a starting point for further work with our Indian design colleagues. Using a similar iterative approach, five additional working models were designed and fabricated focusing on various functional, cultural and aesthetic aspects of the design. These six working models continue to be field-tested in India to obtain further specific user feedback (Figure 1). This information will be used in conjunction with several technical refinements to develop a 'final' design prototype.

RESULTS

The ultimate physical result of this project will be, of course, the final mobility device prototype. However, several important general results have been obtained thus far in the design process. The perceived need for 'low-height short-range' mobility devices in rural and low-income Indian communities was confirmed. Visits to these communities with the devices generated great interest and excitement. The women quickly adapted to the new devices and felt that they would prove very useful in allowing them to participate more fully in the community.

Importantly, it was found via user and therapist feedback that the design should be kept as simple as possible. This had originally been assumed from a technical perspective in order to minimize manufacturing and maintenance costs. That the same philosophy resulted from the functional perspective suggested a major point: the simpler the device, the greater the acceptance. Numerous optional design features were discouraged (folding mechanism, baskets, adjusting seating platforms, etc.). The users felt that many of these additions would interfere with the device's utility by possibly decreasing range of motion and by rendering the design aesthetically 'menacing'. Similarly, the users wanted their device to be as small as possible. It was felt that a small device would detract less attention from the user, and would make it more maneuverable in the small spaces typical of their homes.

Figure 1: User evaluation of the first working model.

Finally, and arguably most importantly, it was found that user feedback was often contradictory to professional opinion. This was true not only in the most obvious scenarios (e.g. a Canadian engineer making poor assumptions regarding Indian activities), but also in less obvious situations (e.g. an Indian designer making poor decisions regarding aesthetic preferences). Without fail, the user much preferred simplicity over complexity, even at the expense of a certain degree of functionality.

DISCUSSION

The traditional engineering design process hinges upon the set of requirements which the system is designed to satisfy. This set, usually called the list of specifications, is typically well defined from the outset and is therefore relatively simple to test for compliance during the subsequent creative phases of the design process. A successful design is defined as one which satisfies all of these requirements or specifications. In complex situations, however, this traditional process suffers severe inadequacies. Not only are the specifications for a complex system difficult to define and evaluate, they often are interdependent variables which are impossible to evaluate individually. To overcome this problem, the relationships between the design specifications must be defined in addition to the design specifications themselves. A successful design in this case requires not only that all the specifications be satisfied, but that the functions describing the relationships between the specifications be accurate and representative. Evaluation of this system is possible when these relationship functions are quantitative and objective, but proves to be extremely difficult when they are qualitative and subjective. The design of appropriate assistive technology, especially in a cross-cultural perspective, is an example of such a complex design problem.

For example, in the mobility device project under consideration, it was specified that the device must be light, strong, inexpensive, functional, and aesthetically pleasing (amongst others). Although it is possible to put specific measures on weight, strength, and cost, it is difficult to know exactly what specific values for each would result in the best device. Furthermore, it is practically impossible to put a meaningful number on functionality or aesthetics - both extremely important design parameters. Even if this quantification were possible, the functions which describe the relationships between the five factors would be too complex to practically model.

In order to address this complexity, a non-traditional approach to design was necessary. In this project, a practical low-cost method was used with great success. This method emphasized user feedback by continually approaching the user with simple, focused models which were designed to stimulate user feedback and not necessarily to immediately provide a 'best' design.

Finally, given the cross-professional and cross-cultural nature of appropriate technology design, collaboration at all stages by the users, the Indian designers, and the Canadian therapists and engineers was crucial for a successful result. It is appropriate in this assistive technology development project that the ultimate decision-making authority is the technology user.

REFERENCES

1. Packer, T. Research Notes. Low-level short- range mobility devices in developing countries. CASMA December 1994, p.4.

2. Hotchkiss, R. Third World Wheelchair Manufacture: Will It Ever Meet the Need? RESNA 13th Annual Conference, Washington, D.C., 1990, pp.309-310.

3. Deshpande, S. Prosthetic Engineer and Head, Department of Prosthetics and Orthotics, All India Institute of Physical Medicine and Rehabilitation. Personal Communication.

4. Hof, H., R. Hotchkiss, and P. Pfaelzer. Building Wheelchairs, Creating Opportunities: Collaborating to Build Wheelchairs in Developing Countries, Technology and Disability 2(2):1-14, 1993.

5. Orpwood, R.D. Design methodology for aids for the disabled. Journal of Medical Engineering and Technology 14(1):2-10, 1990.

ACKNOWLEDGEMENTS

This project is funded by the International Centre for the Advancement of Community Based Rehabilitation (ICACBR) in collaboration with the National Institute of Design, India.

John T. Lysack Department of Mechanical Engineering Queen's University, Kingston ON, K7L 3N6 Canada Tel. (613) 545-6000 x5744 email: lysack@me.queensu.ca

SHORT-RANGE MOBILITY DEVICE