Translating user needs into product design for disabled people: a study of wheelchairs

The challenge in design is to provide users of products with what they really want. Thus, matching customer needs with product characteristics is crucial. Customers are those best able to express their own needs. However, disabled people may find it difficult to articulate what their needs are. The aim of this thesis is to produce a design method in which the "voice of the disabled customer" can be translated into product requirements in a form which designers and manufacturers can use. Wheelchairs were chosen as the product for study. A review of the literature on ergonomics and product design, potentially and actually, applicable to mobility for the disabled is given. There is a discussion of issues including consumer needs, product requirements, consumer satisfaction and products for the disabled. A major part of the thesis is concerned with surveys of wheelchair designers, prescribers (physiotherapists and occupational therapists), rehabilitation engineers, users, and carers on their views on wheelchair design, assessment, prescription and use. It was found that most designers in the survey carried out all phases of the design process based on their assumptions about users' expectations and needs, and not including the users', carers' or prescribers' requirements in the design process. Deficiencies in wheelchair design were recognised by all stakeholders involved in the processes of prescription, supply and use. In addition, many prescribers, rehabilitation engineers, users and carers reported weaknesses in the processes of assessment and prescription. Prescribers and rehabilitation engineers agreed unanimously that such weaknesses have implications for wheelchair design. A surprisingly high number of users and carers rated their own wheelchairs, or the wheelchair belonging to the person whom they assisted, as less than good for certain vital characteristics such as safety, reliability, suitability, manoeuvrability and comfort. Almost all prescribers, rehabilitation engineers, users and carers reported that they had never been involved in wheelchair design with a company that produces wheelchairs for a large market. A user-centred design method for wheelchair design, based on the findings of the literature review and the survey, is presented and the suitability of the method is investigated using the opinions of several wheelchair designers. The thesis concludes with lessons which have been learned and suggestions made for further research.