Figure 1

Kinematical scheme of human hand. The kinematical scheme of the human hand contains the palm and the phalanges as rigid bodies linked by 22 revolute joints. The reference frame x _i O _i y _i z _i is placed on the joint i + 1. The joint variables are q ₁, q ₂, q ₃, q _4k , q _5k , q _6k , q _7k (k = o, m, i, l), the three first corresponding to the wrist, common articulation for all fingers. The bending angle α _i is measured between O _i-1 z _i-1and O _i z _i axes conformably to the positive sense of the O _i x _i . It can be observed that, in the case of the lateral fingers (pinky, ring finger and index), the kinematical chain structure is the same as for the middle finger, the only difference being the values of distances L _k between every origin of the reference frames attached to the proximal fingers' phalanges and the fixed global x ₀ O ₀ y ₀ z ₀ one.