Research Article

Muscle Coordination Control for an Asymmetrically Antagonistic-Driven Musculoskeletal Robot Using Attractor Selection

Figure 2

Muscle coordination and two types of virtual antagonistic muscle structures. (a) Principle of the muscle coordination using the antagonistic muscle ratio and the antagonistic muscle activity . When is 0 (left picture), the pressure for the flexor is high () and the extensor is low (). When is 0.5 (middle picture), the pressure for the flexor and the extensor is identical (). When is 1 (right picture), the pressure for the flexor is low () and the extensor is high (). Therefore, the pressures of the extensor and the flexor are determined by searching for the normalized variable . (b) One of the virtual antagonistic structures. Two muscles are added virtually to the musculoskeletal system (shown in (d)) to form a symmetrically antagonistic arrangement on the intermediate phalange and the proximal phalange. Therefore, the virtual antagonistic structure has three simple antagonistic muscle structures (inset picture in (b)). (c) The other virtual antagonistic muscle structure. Two muscles on the intermediate phalange and the proximal phalange are decreased virtually from the musculoskeletal robot (shown in (d)), and the muscles are symmetrically arranged on the metacarpal. Therefore, the virtual antagonistic structure has one simple antagonistic muscle structure (inset picture in (c)). (d) The real form of the musculoskeletal robot that is controlled. The value of (shown in (a)) is applied to the virtual antagonistic structure (shown in (b) or (c)) virtually transformed from the musculoskeletal robot (shown in (d)).