Figure 13.

(a–f) Walking gait that minimizes the C_F2 cost for springless kneed biped with a linear force–velocity constraint on the knee moment, when V = 0.39, D = 1.38, l_max = 0.95 and F_max = 3. Again, this gait is close to inverted pendulum walking. (g–l) Running gait that minimizes C_w for the springless kneed biped at V = 1.2 and D = 2.8, with a force–velocity relationship for the knee muscle. This gait shows more time-reversal asymmetry in the trajectory and the leg force profile than other gaits here on account of the force–velocity relation.