Recently, the Sports Biomechanics Laboratory completed two projects concerning baseball aerodynamics. The first project determined the initial conditions of the baseball pitch. The second, uses these initial conditions to duplicate the pitch with a pitching machine.
Initial Condition Determination
Primary Researcher - LeRoy Alaways
The focus of this project was the determination of the effect that angular velocity has on the trajectory of the pitched baseballs. This was accomplished by estimating the initial conditions (position, translational velocity, and angular velocity) of the pitch by constructing an accurate aerodynamic model of the pitch and then simulating a pitch with a guessed set of initial conditions. The results of this simulation were then compared with an accurately measured trajectory and the residual vector is computed. This residual vector is then minimized iteratively, by changing the values of the initial condition vector using a nonlinear least squares method. The results of this procedure are highly accurate estimations of the initial conditions of the pitch (see figure below).
Results of this research include the lift, drag and cross-force coefficients for pitched baseballs. A copy of the dissertation and other baseball papers can be found on the following link: Dissertation and papers
Completed March, 2000.
Primary Researcher - Sean Mish
A machine to throw baseball pitches accurately and repeatably has been developed. This machine will release a ball with specified angular and translational velocities to study the effect of release conditions on the ball's flight. In order to control both the spin of the ball and its translational speed, separate mechanisms have been dedicated to each of these tasks. The parameters under automatic control for each pitch are: release angle (both pitch and yaw), translational velocity, spin axis orientation, and spin rate. This machine is intended for use as a scientific instrument. There are currently no plans for commercial production. Initial development was completed in March 2000, additional refinements in the machine can and will occur with incoming students in the following years.