Understanding Player Load: Meanings and Limitations

We present a critical reflection on the mechanical variable Player Load, which is based on acceleration data and commonly used in sports. Our motivation to write this paper came from the difficulties that we encountered in the calculation and interpretation of Player Load using our own data, since we did not use the Catapult Sports equipment, which is a merchandise of the company that proposed this variable. We reviewed existing literature in order to understand Player Load better; we found many inconsistencies in PL calculation methods and in the meanings attached to it. Accordingly, this paper presents a brief discussion on the meanings that have been assigned to Player Load, its limitations, and the lack of clear and complete information about Player Load calculation methods. Moreover, the use of arbitrary units and different practical meanings in the literature has associated Player Load with many physical quantities, thereby resulting in difficulties in determining what Player Load measures within the context of sports. It seems that Player Load is related to the magnitude of changes in acceleration, but not the magnitude of acceleration itself. Therefore, coaches and sports scientists should take this information into account when they use Player Load to prescribe and monitor external loads. We concluded that a deeper discussion of Player Load as a descriptor of external load is warranted in the sports sciences literature.

Novel Method of FKP Feature Extraction Using Mechanical Variable

Feature extraction is one of the most essential phase in biometric authentication. It helps in extracting and measuring the biometric image as ideal as possible. These features sets can be used further for image matching, recognition or learning techniques in supervised algorithms. In the proposed work a novel features extraction method for finger knuckle print is explored with comparative analysis. The proposed scheme is based on different mechanical variables and its efficiency also proved by plotting different curves in Matlab R2009a.

Development of Mechanical-Impedance-Varying Mechanism in Admittance Control

There have been numerous studies on the physical human-robot cooperative task system with impedance/admittance control in robot motion control. However, the problem of stability persists, wherein the control system becomes unstable when the robot comes into contact with a highly stiff environment. A variable impedance control strategy was proposed to circumvent this stability problem. However, a number of studies on variable impedance control are based on the variation of a parameter in the robot motion control software, and a mechanical variable impedance control has not been proposed. The purpose of this research is to propose a mechanical variable impedance control strategy using a mechanical device based on the lever principle. The proposed mechanism can adjust the magnitude of the input force to the force sensor by changing the position of application of the operating force on the beam. Adjusting the magnitude of the input force to the force sensor is equivalent to varying the impedance parameters of the robot; therefore, it is feasible to achieve mechanical variable impedance control using the proposed mechanism. In this study, the gain adjustment characteristics of the proposed mechanism were evaluated. The experimental results demonstrated that the operator can vary the impedance parameters of the robot by mechanically adjusting the input force to the force sensor and operating the robot using the proposed mechanism.

A Dual-Limit-Erosion Approach to Estimate Fracture Zone of RC Slabs Subjected to High Velocity Impact Loads

This paper presents a novel erosion approach to reproduce fracture of concrete subjected to impact loadings. An erosion method is a numerical technique to remove highly distorted Lagrangian meshes which, if not deleted, tend to decrease the accuracy of numerical results obtained and often cause to terminate the calculation prematurely. Existing erosion criteria generally use a single thermo-mechanical variable for the deformation measure such as strain, stress tensor or damage. In this study we propose to utilize two measures to activate the erosion function with a view to better reproducing fracture zones of concrete by distinguishing the element deformation in compression or tension state. Test calculations in two and three dimensions are carried out to investigate the applicability of the proposed erosion method, and the numerical results are discussed with reference to available experimental data.