Figure 2.

(a) Human-sized humanoid robot, CB-i [42]: height: 1.55 m, total weight: 85 kg. The robot is equipped with 51 d.f.: 2 × 7 d.f. legs, 2 × 7 d.f. arms, 2 × 2 d.f. eyes, 3 d.f. neck/head, 1-d.f. mouth, 3 d.f. torso and 2 × 6 d.f. hands. It has similar configurations, range of motion, power and strength as a human body to reproduce better natural human-like movements, particularly for locomotion and object manipulation. (b) Exoskeleton robot (XoR) [43]. Height: 1.5 m, weight: 30 kg. XoR has 10 d.f. and six active joints, each of which uses a hybrid actuator composed of an air muscle and an electric motor. It is designed to assist lower limb movements of human users. (Online version in colour.)