Morphology
The figures are represented as rigid bodies made of interconnected limbs of varying lengths, joined at various angles. Each figure conforms to a tree-like topology - no closed loops can occur among the parts. The orientations of the limbs are hierarchical, as in most skeletal systems (for instance, when your elbow bends, everything from the elbow down rotates about the elbow joint). A body is deformable internally (autonomous changing of joint angles) but is rigid in the sense that it does not deform passively in response to environmental stimuli, such as collisions. The human form emerged from the animal kingdom through natural selection according to Darwinism. Likewise, in this little world, human-like forms can emerge. In the spirit of artificial life studies, I have made most of the species of articulated figures have variable morphologies. The number of limbs, the angles at which limbs are connected, and the lengths of the limbs can vary according to genetic variation. This opens up the arena for many possible forms as well as motions. Appendix A offers a detailed explanation of the scheme for morphology developed for the Vertebrates. Figure 10 shows four examples from the Vertebrates, and demonstrates the variety of morphology in an initial un-evolved population.
Figure 10 Four examples of the Vertebrates, the most complex of the articulated figure species, demonstrating morphological variation.
I have experimented with evolving the Vertebrates without any interactive intervention, with fitness pressures for locomotion to see what would spontaneously emerge. The most interesting finding is the fact that morphology and motion behavior usually evolve in tandem. A form can constrain a motion style, but also a highly fit motion style can encourage emergence of forms which support that motion style. These notions were the impetus for an artificial life experiment I had developed parallel to this thesis for exploring emergent morphology along with locomotion (Ventrella, 94). It was demonstrated that anatomies and locomotion behaviors reminiscent of some familiar species of animals tended to emerge together. The environment for this artificial life experiment has been folded into the Character Evolution Tool so that one can explore emergent morphologies and motions for their own sake.
MOTOR CONTROL
