35

Figure 3.8 shows the open loop motion resulting when the base PCG alone is used for control.

As expected, the biped falls over after several steps.

Side view

Rear view

Side view

(continued)

Rear view

(continued)

Figure 3.8 -

Unbalanced motion of human model using base PCG
shown in Figure 3.7.

Surprisingly, the small number of poses is sufficient not only for walking, but also for a limited

form of running.

Running can be achieved simply by replacing the 0.2 second time-based

transitions of the walking base PCG with 0.1 second transitions.

The flexibility of the pose

controller to accommodate the different motions is due to the ground sensors which are used in

state transitions. The sensor-based transitions exist to ensure that the next stance foot is in contact

with the ground before proceeding into its stance phase.

However, they do not constrain the

initial time of ground contact. In the case of running, ground contact typically occurs shortly after

entering state S1 or S4 as the new stance leg moves to propel the biped forward.

In the case of