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Impact models are an important tool for golf equipment design as they allow for computer simulations to evaluate and optimize performance. There are several published driver impact models for this purpose. However, existing impact models have no or limited experimental validation to support their conclusions. The aim of this research was to extend several impact models from the literature to predict three-dimensional driver impacts and, for the first time, iron impacts. The accuracy of these models was evaluated using experimental data. Two impulse-momentum and three continuous contact models were applied to create dynamic models to predict driver and iron golf shots. While finite element models are used to design golf clubs, they were not considered here due to their high computational requirements. For modeling driver impacts, an adjusted IM model was the most accurate at predicting ball launch conditions. Ball speed was the most accurate launch condition with a mean absolute error of 1%. The error for vertical launch angle and backspin was less than 10%. However, the error for sidespin and horizontal launch angle (azimuth) was between 30 and 50%. For modeling 7-iron shots, a two-layer ball with a volumetric normal force model was the most accurate of the models considered. The experimental error for ball speed was 2%. The remaining errors were similar to the driver model. [ABSTRACT FROM AUTHOR]

There are many factors that influence the amount of side-spin imparted to a golf ball during impact with a driver. In general, the best golf drives are launched with minimal side-spin, producing a straight ball trajectory with maximum carry distance. During off-centre impacts, side-spin is generated due to a phenomenon known as the “gear effect.” The extent of the gear effect depends on clubhead design parameters such as the moment of inertia and centre of gravity location. The bulge of a driver is a design feature implemented to counter-act the side-spin produced by the gear effect. In this investigation, an impulse-momentum impact model and an aerodynamic ball flight model are used to (i) examine the effect of the centre of gravity depth (distance from clubface) on ball trajectory during off-centre impacts, (ii) test the efficacy of movable weight technology, and (iii) optimize the bulge radius in relation to the clubhead's centre of gravity depth and moment of inertia. In the first study, it is qualitatively shown that side-spin increases linearly with increasing centre of gravity depth. In the second study, it is found that movable weights can have a significant effect on ball trajectory, especially at higher swing speeds. In the third study, a relationship between the bulge radius, centre of gravity depth, and moment of inertia is developed, and an equation for calculating the optimum bulge radius is fit to the simulation results. [ABSTRACT FROM AUTHOR]

Abstract: We compare optical tracking with inertial tracking of a golf club for full golf swings. Previous work on tracking golf clubs with inertial measurement units (IMUs) was limited to putting applications . Using a Vicon optical motion capture system and a commercial micro-electromechanical-system (MEMS) IMU, we performed simultaneous optical and inertial measurements of golf swings by one of our varsity golf team members. The IMU and five optical tracking markers were attached to a club shaft just under the grip. The position and orientation data of the grip can be used with a dynamics simulation of the club shaft and head to yield information about the club face launch conditions at the moment of ball impact . Vicon marker position data, and IMU accelerations and rotation rates, were converted into laboratory frame position and orientation data for the grip of the club and compared with one another. The results point to challenges with commercial-grade IMUs that use MEMS for tracking golf swings. Strapdown inertial navigation is very sensitive to errors in the rotation rate and acceleration sensors. Due to the large dynamic ranges involved in a golf swing, and the poor noise, stability, and dynamic range of the MEMS IMUs, high-fidelity tracking of the 6-degree-of freedom grip motion could not be achieved. We suggest that a way to overcome these challenges could be by including magnetometer data with an extended Kalman filter to provide the necessary accuracy in orientation to reconstruct the position of the club accurately in three dimensions. [Copyright &y& Elsevier]

Abstract: Player testing was conducted to assess the effects of different golf shaft alignment methods on 5-iron golf club performance. Two steel-shafted irons, one aligned using the Spining method and one aligned using the SST PURE1 method, were tested versus a non-aligned club. A series of player tests were performed on +2 to 3 handicappers, using a golf simulator from aboutGolf . Statistical analysis was performed on 6 variables retrieved from the golf simulator for 400 golf shots hit by 5 participants. Player feedback on the feel of each randomly hit golf club was also recorded. Results show that the alignment of golf shafts does have an effect on some of the shot variables. The Spining method was confirmed to have a statistically significant effect on the vertical launch angle of shots. The PUREing1 method was found to result in a slightly greater carry distance, and may offer better feel. [Copyright &y& Elsevier]

The article focuses on the use of a finite element (FE) model to demonstrate the impact dynamics of a golf drive. A description of the impact between the clubhead and golf is provided to obtain insight into driver design and performance. It outlines the three stages of the optimization process for which the includes FE model was modified and used. A comparison of results of the impact simulation using FE model with those obtained using impedance matching theory is discussed.