This paper interprets an outfielder's action pursuing and catching a fly ball in terms of the behavior of a closed loop system by taking Chapman's hypothesis into the system connecting perceptions and actions. Through the analysis, we make it clear that the hypothetical trajectory Chapman showed was a special dynamic solution of the closed loop system. Moreover, it is shown that the proposed feedback control law makes it possible to generate a pursuing trajectory automatically that a fly ball can be caught at the right place at the right time. It is also shown that the pursuing trajectory gets closer to the one Chapman showed as a feedback gain increases. In addition, we compare the proposed feedback control law with Proportional Navigation (PN) which is the most common navigation technique for tracking moving objects, and show that the proposed method performs favorably over PN.
