Towards the integrated measurement of hand and object interaction

This paper describes the first stages towards an integrated package of quantitative methods for the measurement of hand-object interaction. To date, quantitative data concerning a product's ease of use has not been adequately defined to assist product developers and legislators in their evaluation. A better understanding is needed of the complex interaction between the hand and an object during task performance A model of the physical interaction between hand and object is described that emphasises the role of the biomaterials of the hand rather than focusing on the conscious implementation of muscle involvement. The model subdivides hand-object interaction during grip into three levels: Gross interaction where the skeletal structure and muscles influence the grip pattern providing a mechanical structure to clamp the object; Intermediate interaction, where the soft tissues of the palm of the hand provide a mechanical interlock with the surface features of an object; and Micro interaction, which involves adhesion between the sebum, epidermis and surface material of the object. This model of hand-object interaction provides a contextual framework for the measurement of levels of hand-object interaction. A battery of methods, which includes consideration of anthropometry, joint range of movement, grip strength, finger compliance, finger friction and the measurement of dynamic task performance, is described. A case study is used to illustrate the potential application of such data for the design/redesign of a product.