Design methodology for aids for the disabled

Although many aids for the disabled appear to be quite simple, their design is subject to many difficulties. These problems arise because of the intimate relationship between the equipment and the human body. Equipment design is therefore affected by many biological variables that are difficult to define at the beginning of the design exercise and many will not even be obvious until a device is tried out with a user. Standard design methodologies rely on all the variables being defined in a thorough specification at the start of the design process and therefore often lead to ineffective devices or very long development programmes. An alternative methodology is presented which overcomes the problems by separating the user interface aspects of the design from the supporting features. The user interface aspects are then allowed to evolve in conjunction with tests with potential users and finally integrated with the supporting features once a satisfactory solution has been found. Much more effective devices result with much shorter development effort.