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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.

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Featured Application: The strain propagation findings presented in this paper justify the continued use of golf robots in studies investigating steel-shafted clubhead dynamics at ball impact, given that the gripping mechanism has a negligible effect on the collision dynamics.Abstract: Research and equipment testing with golf robots offers much greater control and manipulation of experimental variables compared to tests using human golfers. However, whilst it is acknowledged that the club gripping mechanism of a robot is dissimilar to that of a human, there appears to be no scientific findings on the effects of these gripping differences on the clubhead at ball impact. Theoretical and experimental strain propagation rates from the clubhead to the grip and back to the clubhead were determined during robot testing with a 9-iron to determine if this time interval was sufficiently short to permit the gripping mechanism to have an effect on the clubhead during impact. Longitudinal strain appears to propagate the most quickly, but such deflections are likely to be small and therefore of little meaningful consequence. Shaft bending was not a primary concern as modes of large enough amplitude appear to propagate too slowly to be relevant. Torsional strain propagates at a rate which suggests that constraints at the grip end of a golf club could potentially influence impact dynamics for steel shafted irons; however, this effect seems unlikely to be significant, a likelihood that decreases further for longer irons. As such, it is considered reasonable to treat the influence of a robot's gripping mechanism on clubhead dynamics at impact as negligible, and therefore comparisons between robot and human data in this regard are valid.