It is difficult to fully automatize the materials handling process which is contained in many industrial processes. Although it needs devices that can operate in three dimensions, they have scarcely been investigated. Some basic informations to construct such devices are pressented in this paper.
As human fingers are seemed to be the best model, the author analysed their function from the viewpoint of degree of freedom. The relations between fingers and objects are classified and the fundamental relations are selected out. Then, how the increase of the degree of freedom effects the function of fingers is analysed. Its results are given in chart. This chart is named “capability chart” by the author. A formula is introduced to estimate the function of fingers relating to their number and degree of freedom, and a calculated example is given. The results are as follows; the function of fingers becomes higher as their degree of freedom increases to some extent. When the degree becomes some number, the increase of the function is little, then one finger is added, the function increases as before.