Validation of Sensor-Based Game Analysis Tools in Tennis

Abstract Three inertial measurement unit (IMU) based tennis sensor systems from BABOLAT (PURE DRIVE PLAY, POP) and HEAD (Tennis Sensor) and a camera-based system (PlaySight) were tested with respect to the question whether the information about the number of strokes by swing type and spin type in training exercises and/or matches and the average as well as the maximum speed of the service per session are reliable. Subsequently, the question whether the mechanical properties of the BABOLAT PURE DRIVE PLAY racket are the same as the mechanical properties of the BABOLAT PURE DRIVE racket without IMU was addressed. For swing types in standard exercises the results are acceptable for forehand groundstrokes, backhand groundstrokes and services but not for volleys. In a match environment we find inacceptably high errors (>10%) for the number of strokes for forehand and completely inacceptable levels for volley. The wrist-based IMU of BABOLAT POP has not reached an acceptable accuracy at all. For spin types the results are acceptable. The large variances in service speed assessment between devices make it doubtful whether any of them may be used for the control of training processes aiming at increasing the average service speed The mechanical properties of the BABOLAT rackets with and without IMU are quite the same.