OPTIMIZATION OF THE CLUBFACE SHAPE OF A GOLF DRIVER TO MINIMIZE DISPERSION OF OFF-CENTER SHOTS

The objective was to optimize the post-impact conditions of a golf dri ver and golf ball in order to minimize dispersion of a drive for off-c enter hits. When a golf ball is struct by a clubhead at a point away f rom the ''sweetspot'' on the clubface, spin is induced on the ball whi ch makes it curve during flight. Over the years, clubmakers have made the clubface slightly convex in shape in order make off-center hits la nd as close to the fairway as possible. A general, three-dimensional i mpact model using principles of momentum conservation on rigid bodies was used to extract the spin and velocity vectors of the ball after im pact. An aerodynamic model including drag, lift and skin friction was then used to obtain the landing position of the ball. An optimization routine was used to calculate the optimum clubface shape to minimize g olf ball dispersion from the middle of the fairway, for off-center hit s. In order to have an accurate simulation of impact on a computer, th e mass and inertia tensor of the clubhead was experimentally measured. The clubface shape relative to the center of gravity of the clubhead was also measured. The impact computer program and golf ball trajector y computer programs were verified by using the golfing robot ''Iron By ron'' to hit various shots on the clubface of a particular driver. The computer simulation yielded results of ball landing positions from th e middle of the fairway that fell within the standard deviations of th ose experimentally measured. The optimization routine was used to find the optimum clubface shape to minimize golf ball dispersion for off-c enter hits, for a particular driver swung at a certain initial velocit y in a certain direction. The clubface shape was modeled in the impact program as an ellipsoid. After running the optimization program, the average dispersion from the middle of the fairway for the worst possib le off-center hit locations was reduced on the average from 8.075 to 2 .198 yards. The optimization program demonstrated its effectiveness in determining the optimum clubface to minimize dispersion of off-center hits.