Identifying the Inertial Properties of a Padel Racket: An Experimental Maneuverability Proposal

Musculoskeletal disorders in padel: from biomechanics to sonography

Padel is a racket sport, combining high-frequency and low-intensity athletic gestures, that has been gaining growing scientific interest in recent years. Musculoskeletal injuries are very common among padel players with an incidence rate of 3 per 1000 h of training and 8 per 1000 matches. To the best of our knowledge, a comprehensive collection describing the most common sonographic findings in padel players with musculoskeletal injuries is lacking in the pertinent literature. In this sense, starting from the biomechanical features of padel-specific gestures we have reported the ultrasonographic patterns of most frequent injuries involving the upper limb, the trunk, and the lower limb. Indeed, comprehensive knowledge of the biomechanical and clinical features of musculoskeletal injuries in padel is paramount to accurately perform a detailed ultrasound examination of the affected anatomical site. So, the present investigation aims to provide a practical guide, simple and ready-to-use in daily practice, to optimize the sonographic assessment of padel players by combining it with the clinical findings and the biomechanical features of athletic gestures.

Identifying the Sweet Spot of Padel Rackets with a Robot

Although the vibration of rackets and the location of the sweet spot for players when hitting the ball is crucial, manufacturers do not specify this behavior precisely. This article analyses padel rackets, provides a solution to determine the sweet spot position (SSP), quantifies its behavior, and determines the level of vibration transmitted along the racket handle. The proposed methods serve to locate the SSP without quantifying it. This article demonstrates the development of equipment capable of analyzing the vibration behavior of padel rackets. To do so, it employs a robot that moves along the surface of the padel racket, striking it along its central line. Accelerometers are placed on a movable cradle where rackets are positioned and adjusted. A method for analyzing accelerometer signals to quantify vibration severity is proposed. The SSP and vibration behavior along the central line are determined and quantified. As a result of the study, 225 padel rackets are analyzed and compared. SSP is independent of the padel racket shape, balance, weight, moment of inertia, and padel racket shape (tear, diamond, or round) and is not located at the same position as the center of percussion.

Research on the Measurement Technology of Rotational Inertia of Rigid Body Based on the Principles of Monocular Vision and Torsion Pendulum

Damping is an important factor contributing to errors in the measurement of rotational inertia using the torsion pendulum method. Identifying the system damping allows for minimizing the measurement errors of rotational inertia, and accurate continuous sampling of torsional vibration angular displacement is the key to realizing system damping identification. To address this issue, this paper proposes a novel method for measuring the rotational inertia of rigid bodies based on monocular vision and the torsion pendulum method. In this study, a mathematical model of torsional oscillation under a linear damping condition is established, and an analytical relationship between the damping coefficient, torsional period, and measured rotational inertia is obtained. A high-speed industrial camera is used to continuously photograph the markers on a torsion vibration motion test bench. After several data processing steps, including image preprocessing, edge detection, and feature extraction, with the aid of a geometric model of the imaging system, the angular displacement of each frame of the image corresponding to the torsion vibration motion is calculated. From the characteristic points on the angular displacement curve, the period and amplitude modulation parameters of the torsion vibration motion can be obtained, and finally the rotational inertia of the load can be derived. The experimental results demonstrate that the proposed method and system described in this paper can achieve accurate measurements of the rotational inertia of objects. Within the range of 0-100 × 10^-3 kg·m², the standard deviation of the measurements is better than 0.90 × 10^-4 kg·m², and the absolute value of the measurement error is less than 2.00 × 10^-4 kg·m². Compared to conventional torsion pendulum methods, the proposed method effectively identifies damping using machine vision, thereby significantly reducing measurement errors caused by damping. The system has a simple structure, low cost, and promising prospects for practical applications.