This is a review of the Hawk-Eye Electronic Line-Calling System Data research conducted by Simon Choppin, Simon Albrtecht, James Spurr, and Jamie Capel-Davies.
As technology has improved, the ability to analyze the game of tennis has been enhanced. One such technology is the Hawk-Eye Electronic Line-calling System. This system automatically tracks the ball and players during a game, producing such data as ball velocity, bounce locations, and flight trajectories of the ball. This system also gives players the ability to challenge line-calling decisions. The data produced by the system is used to generate statistics during a game but is also used for scientific research. The data has allowed sports engineers to evaluate the effectiveness of the equipment being used by the players.
One important piece of equipment in a tennis game is the ball itself. The data produced by the Hawk-Eye Electronic Line-Calling System has been used to research the effect wear has on a ball’s aerodynamics and how it affects the play.
A data set was created from 364 matches played during the 2012 to 2017 Davis and Fed Cup tournaments. The data included 71,019 total points. Three data tables were created. The first was a match data table, which included information such as the players involved, the tournament, and the date the match was played. The next table was the point table, which included information about the flow of the game. This included who was serving, the current score, the winner of the point, etc. The third table was the shot data table, which included information regarding the physical characteristics of a shot such as the impact the racket, had on the ball, how the ball passed the net, and the impact the ball had on the court.
Following this, the type of ball used in each point was determined. A ball was considered new during the first two games it was used. A ball was considered used during the last two games it was used. On average, a ball was hit with a racket 39 times before being exchanged for another ball.
To determine the aerodynamics of the balls only first serves were looked at. The deceleration of the ball between being hit with the racket and making contact with the court was calculated. It was determined that serve speeds were slighting higher with new balls resulting in higher impact speeds on the court and less time in the air. New balls slow down less than used balls as the felt of a used ball is actually raised up rather than flattened.
Further study is needed to look at whether serving with a new ball has a psychological impact on the player and how different types of rackets change the impact they have on the ball and the resulting velocities.
As this study is refined, tournaments can use the resulting information to determine the optimal time to introduce new balls into a match.
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