Resolution of Ill-posed Problems in Optimal Motor Control by Interaction of Task Requirements and Bodily Constraints: Analysis of Throwing Task from a Developmental Perspective

One of the fundamental problems in motor control theory is ill-posedness, and the principle that the agent ororganism selects one among many possible solutions to their motor task. Two theoretical approaches have been proposedto explain the mechanism that resolves this ill-posedness: One is based on optimal control theory, and the otherdynamical system theory. However, since these two approaches consider it under their own theoretical assumptions,either approach alone may not be sufficient for a broad range of realistic motor tasks that usually have characteristicsof both approaches. The present study analyzed a throwing task that allows us to clearly define the task performance(error), as required by optimal control approach. By analyzing the motor task from the developmental perspective—emphasizing the natural fact that the constraints on task, environment, and body can be dynamic and changing—,we showed mathematically and computationally that a type of ill-posedness in this motor task can be manipulated andthen resolved. We discussed potential applications of these findings to curriculum learning in artificial intelligenceresearch.