AN INNOVATIVE DEVICE FOR MEASURING ACCURACY OF THROWING IN HANDBALL
Keywords: electronic device, accuracy, throwing data
AbstractA digital electronic device was constructed in order to measure the accuracy of throwing in handball. This innovative device consists of two parts: a) the central unit which generates visual stimuli and collects data and b) tabloids. HARDWARE AND SOFTWARE SPECIFICATION: The device consists of three independent tabloids placed inside and connected to the handball goal post. The dimensions of the two vertical tabloids are 200x60x2cm, and those of the horizontal 180´60´2cm. The dimensions of the goal post are 300´200´8 cm, constituting a total surface of 60,000 cm2, of 38,400 cm2 are covered by the tabloids. A total of 2,130 holes were made in all three tabloids. The same number of light emitting diodes (LED) were placed on the back side of each tabloid in each hole so that they would be visible on the front side. The LED’s were placed in such a way as to form a net of squares (40´40mm). One of these squares, when lit up, determined the ‘target-point’ to be hit in a throw (shot). The net of LED’s was interwoven with metal strips (10mm wide and 1 mm thick) which lay at a distance of » 2mm from each other, forming another net of squares (40´40mm). These strips served as ‘hit-detectors’. When the ball hits a specific point on the metal strips, an electrical contact is produced which is transferred to the central unit, after having been processed by the multiplexer - demultiplexer. In this way the coordinates of the point hit by the ball are registered with very high accuracy (1mm). The biggest error in hit-detection (i.e., the largest distance from the strip) occurs in the case of the ball hitting the LEDs (20 mm ´ Ö 2 = 28.3 mm). This data collection system is based on the micro-processor INTEL 8085, which, in combination with the other regional units (serial communication port, LCD. display, ROM and RAM 32 Kbytes,) comprises the integrated control device (Fig 1). [Figure] Fig 1 Electronic configuration of visual stimuli generator and throwing data collection unit CONCLUSIONS: With the above described device it was possible to register the following: a) the coordinates of the lit up ‘target-point’ on the tabloid, visually displaying the beginning of the throwing attempt, b) the coordinates of the contact point on the tabloid hit by the ball, c) the duration of the contact with an accuracy of 5ms and d) the time elapsing from the visual stimulus until the contact of the ball with the tabloid. The implementation of this innovative device was carried out with measurements taken from athletes with various levels of handball playing ability.
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