Virtual fitting trials in 'design for all'

‘Design for all’ embraces the concept of designing products and workplaces so as not to exclude significant sections of the total user population. In particular, the needs of old and disabled people are to be considered alongside the younger and able-bodied population to ensure that products that are equally appropriate for all users. This is to be contrasted with a ‘design for the disabled’ approach where the special needs of disabled people are considered in order to provide products that may only be appropriate for that section of society. Fitting trials are an established technique in ergonomics where a product or workplace is evaluated by trials (perhaps on a mock-up or prototype) using a carefully selected user group that is representative of the total target population. Typically, subject selection would be based on age, gender, size, etc., and total sample sizes limited to perhaps a few dozen. A percentage of the population accommodated by the design can then be determined by reference to a set of elemental tasks such as reaching to controls. In this research, the fitting trials are virtual in that computer modelling techniques are used to create a three-dimensional geometric model of the workplace/product and evaluation is achieved using a human model that can be varied to represent the individuals within the sample. There is a lack of anthropometric and biomechanical data relating to older and disabled people so a small-scale survey is being undertaken so that an appropriate population of computer human models can be created. Methods are being developed to allow the percentage accommodated by a design to be determined in relation to a description of tasks to be carried out. Currently, an ATM (automated teller machine) design is being used as a case study to develop these techniques. Further research will eventually be undertaken to extend the data, generalise the percentage accommodation evaluation and optimise the design in terms of percentage accommodation.