Spin Rate Measurements in Cricket Bowling Using Magnetometers

Abstract

The ability to measure and classify spin has been of great interest to cricket organizations, coaches, and athletes. While video is common, an alternative approach is to use 3D motion capture analysis with reflective spheres, which changes the aerodynamics of the ball. An instrumented cricket ball has proved to be effective in measuring high-speed spin rates using gyroscopes. In this study, an instrumented ball with a 3-axis accelerometer, 3-axis gyroscope, and 3-axis magnetometer located at the center mass of the ball was constructed. The spin rate was calculated using the magnetometer, and two spin types (off-spin and leg-spin) were classified. The sensor data was validated using motion capture. In addition, inertial measurement units (IMUs) mounted on the wrist and elbow of a wrist-spin and off-spin bowler were used to verify and validate the spin classification. The magnetometer can be effectively used in conjunction with conventional IMU sensors on the bowler’s arm to tailor training sessions by addressing deficiencies identified in a bowler’s spinning technique and to monitor their performance.

The Biomechanics of Converting Torque into Spin Rate in Spin Bowlers Analyzed with a Smart Cricket Ball

“…This distinguishes our Smart Ball from the Kookaburra Smart Ball (Kookaburra, Melbourne, Australia), which only calculates one spin rate data value in the early phase of the ball's flight. The magnetometer data's oscillation frequency appears to be the underlying source of the spin rate information [ 11 ], since commercially available low-speed gyroscopes possess the capability to measure spin rates only up to 5.5 rps. Only one specific gyroscope (InvenSense, San Jose, California, USA) can measure up to 11 rps.…”

Mobile Computing with a Smart Cricket Ball: Discovery of Novel Performance Parameters and Their Practical Application to Performance Analysis, Advanced Profiling, Talent Identification and Training Interventions of Spin Bowlers

“…The reason for this was that we focussed on the spin rate, which is more important than the translational speed in spin bowling, and also enabled computing the ten performance parameters. Conversely, calculating the spin rate from the magnetometer signal [ 24 ], as done by commercially available smart balls (baseball and cricket), does not allow determining further parameters beyond the spin rate (at release or pre/post-bounce). Note that all 10 performance parameters ( Table 1 ) are calculated merely from the variable angular velocity (and the moment of inertia of the ball which is just a constant).…”

“…The first commercial smart cricket ball was introduced by Kookaburra in 2019/2020, measuring the speed and spin rate at the release point and before the bounce, and the speed after the bounce [ 23 ]. Owing to the lack of high-speed gyros, the spin rate is estimated from the frequency of the magnetometer signal during the flight of the ball [ 24 ]. This commercially available ball was developed “ to offer a fun, engaging and educational platform that lets players, coaches and fans engage with the sport on a whole new level ” [ 25 ], while [ 26 ] claims that this “ Smart Cricket Ball measures your bowling performance ”.…”

Accessibility of Motion Capture as a Tool for Sports Performance Enhancement for Beginner and Intermediate Cricket Players

“…This technology has the potential to revolutionize the way that spin bowling is analyzed and trained. It could help bowlers improve their technique and consistency, and it could also help coaches identify and address deficiencies in bowlers’ techniques [ 57 ]. Coaches can use the findings of the study to identify key performance indicators (KPIs) for spin bowlers.…”