The laws of physics and the principles of biomechanics shape the appearance of animal motion. Therefore, the best way to achieve realistic locomotion is to simulate their effects. According to mechanics, the change of the state of an object, or what we commonly call ``movement'', is caused by forces. The motion of an inanimate object, such as a stone, is generally caused by unbalanced external forces and hence is passive. The motion of an animal, on the other hand, is generally initiated by unbalanced internal forces actively generated by its muscles and hence is active. Each species of animal has its particular body structure and arrangement of muscles. This in turn dictates its particular mode of locomotion. We therefore construct simulated physical bodies for our artificial animals. By doing so, the laws of physics will guarantee the physical correctness of the resulting motion, while the biomechanical principles relevant to the animal of interest can yield natural muscle actions that simulate the particular locomotion patterns characteristic of the animal in its physical environment.
|Xiaoyuan Tu||January 1996|