A novel system for tracking iron golf clubheads

Abstract

The importance of iron play to scoring in golf is widely recognised. To better understand this relationship, accurate, yet unobtrusive measurement techniques are required to capture information about the collision between the golf club and ball. This article presents a method for tracking an iron clubhead prior to impact with the ball. Using repeated shots by a golf robot with a 5-iron and 9-iron, the system reliably measured clubhead speed (standard deviation ≤ 0.5 mile/h), face angle (≤0.2°), club path (≤0.2°), effective loft (≤0.5°), attack angle (≤0.1°) and effective lie (≤0.3°). Impact position was within a standard deviation ≤ 0.6 mm for repeated shots. Absolute accuracy of horizontal impact position at initial contact was <1 mm, whereas a systematic offset of up to 4 mm was found for vertical impact position compared to tests using impact location tape. This offset was dependent on the loft of the club and could be explained by the interaction between ball and club during contact. In addition, a unique feature of the algorithm is presented which categorises impacts commonly known as ‘top’, ‘thin’, ‘good’ or ‘heavy’ shots, which is facilitated through tracking of the bottom edge of the clubhead using virtual markers. Hence, this tracking system is presented as a novel solution to accurately measure clubhead presentation and initial ball impact location for irons.