Contents 1. INTRODUCTION
A comprehensive understanding of hand forces is important for developing appropriate strategies and working procedures geared to reduce these disorders. Orientation relationships of hand forces relative to the hand and arm anatomical structures can provide critical information for determining the forces and stresses acting on the muscles, joints, and bones of the hand-wrist-arm system. More detailed hand force information is also desired for the development of safer and more efficient hand tools. To fully characterize grip forces applied to cylindrical handles, it is essential to know how the grip force can be appropriately described and quantified on such handles. So far, grip forces applied to such handles have been usually measured in a single axis, e.g., [1]. This approach has been widely used to monitor and control the grip force during glove tests, biodynamic response measurements, and many other experiments involving hand grip simulations, e.g., [2].
