A philosophical perspective on studies of human movement

Two issues are presented. 1, A philosophical perspective on the development of computationally-based representation, modeling, control and animation of human movement; and 2, the role played by rigid body dynamics. The central nervous system (CNS) in humans is the most advanced and amazing natural system in existence. One needs all the tools; experimental, psycho-physical, developmental, neuroscience-based, and physiological methodologies, in addition to the computational method, if there is to be any hope of understanding such a complex system thoroughly. For the computational method, study of movement is simpler than the study of other brain attributes: vision, speech, memory, learning, hearing, etc. Movement is distributed and spread over the body. It is more easily accessible to detailed observation. It is subject to easier invasive and noninvasive measurement. Computational studies of human movement should facilitate the understanding of the spinal cord, and possibly the design of artificial spinal cords for robots, humanoids and the injured. The spinal cord, in turn, being a rich two way access to the brain for distributed control, signal processing and signal transmission, should help in better understanding of brain function. One is led to computational models that are systematic and, at different levels of complexity and physiological accuracy, imitate natural motion. The models should allow insertion of ligaments, cartilage, muscles, and soft tissues. Particular representations of rigid body dynamics are needed for modeling the skeleton and various joints with different degrees of freedom. They are also important for implementing contact and connection with the environment, or objects in the environment, as well as, other attributes of human movement such as work, dance, competition, locomotion, etc. Needless to say, the models are expected to support and complement experimental and other studies that deal with human posture and movement.