Human based algorithms; to catch fly balls have been research and studied. In the paper, the validity of the human models are tested by catching balls that are dropped vertically downward. The regular OAC (optical acceleration cancellation) and the inverted OAC models are simulated first, and then tested experimentally with a mobile robot. The simulation and the experimental results show that both methods are able to intercept the dropped ball, but the initial and final motions are different. A digital image processing program, DVRobot, was written to process digital images very quickly.