Figure 3.

(a) Renderings of the progression of the first postural synergy of the hand. The top-left frame depicts the hand in the relaxed state, whereas the bottom-right frame depicts the hand after it has moved through the maximum range of the first postural synergy in the positive direction (flexion). Images of the hand were rendered using the LibHand library (Šaric, 2011) and the dataset recorded by Santello et al. (1998). (b) The multichannel pulley, which supported the synergistic motion patterns, has different diameter channels for the thumb, middle, and index fingers. (c) The principle of soft postural synergies proposed in Bicchi et al. (2011), as applied to the soft robotic glove. The hard constraints imposed by the design of the pulley are softened by the compliance of the fabric and cable transmission; this increases adaptability of the glove to grasping objects of different shapes.