SU1424861A1 - Method of determining the height of ball at the time of hitting it in volleyball - Google Patents

Abstract

The acquisition relates to sports and allows you to accurately determine the height of the ball at the moment of hitting it when playing volleyball. The time at the moment of hitting the ball by the athlete is determined, then the height of ball B is two consecutive along the flight paths of the ball and the time cha at these points. The parameters found determine the height of the ball at the moment of impact, 2 Il.

Description

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The invention relates to sports games, sports equipment devices and is intended to obtain reliable information about the quantitative characteristics of sports activities (an attack hit on the ball in volleyball).

The purpose of the invention is to improve the accuracy of determining the moment of impact,

FIG. 1 shows a scheme for implementing the method; Fig, 2 is a block diagram of the measuring transducer

The proposed method can be implemented using the technical sietem of the devices shown in FIG. 1, the complex of technical means of the system contains two columns 1 and 2 of light sources arranged vertically for a certain distance n -1 and one from another, for example, 0.2 m , and mounted on a rack for mounting the grid. On the other rack there are two columns 3 and 4 of photocells located at the same distance from each other. In this case, columns 1 and 2 contain light sources and each forms n light beams directed to n photocells installed in columns 3 and 4. On the back side of the volleyball player, an impact sensor 5 is installed, made on the basis of a piezoelectric element and forming moment of impact impulse voltage

one :.

4y. dt

where V is the speed of movement of the sensor

ka at the moment of impact.

Sensor 5 is connected to a radio transmitter 6, which is made on transistors and is installed on the center of a volleyball player. Columns 3 and 4 of the photocells are connected to the measuring transducer 7, which contains the shapers 8 and 9 of photodiode signals, the outputs of which are connected to the inputs of the IF 10 and 11 and to the inputs of the OR circuit 12 and 13. The inputs of the coders 10 and 11 are connected via buffer resistors 14 and 15 with the inputs of the interface 16, the outputs of which are connected to the russodes of the control computer 17, the radio receiver 18 is connected to the output of the pulse generator 19 through one of the inputs of the meter 20 time intervals, the other inputs of which are connected to the output of the OR circuit 12 and 13, and you od connected kvhodu interface 16,

; The proposed method is carried out as follows.

At the moment tj of a volleyball player’s strike at a height, the shock sensor 5 is triggered and the radio transmitter 6 generates a radio pulse that is received by the radio receiver 18 and converted by the pulse former 19 to a pulse 20 that triggers the 20 time interval meter. As it moves, the light crosses the rays incident on ij (i + 1) -, (1 + 2) -th photocells of the column 3, one of which triggers at time t, during its movement. At the output of the imager 8 photodiode signals, electrical signals are generated and The first signal that is triggered via the OR 12 meter is an interval time meter 20. These signals are received through pshfrator 10 in the buffer register 14,

The encoder is designed to convert the output signal of the shaper to the machine code, which is written to the buffer register and, via a command from the computer 17, via the interface 16 enters (READ OUTPUTS of the computer 17. This calculates the number of the (i + 1) th photocell, corresponds to his height h | in column 3, according to the formula

.., 1 + (L-H) + (i + 2) IV J

where i (t2 is the number of the photocell corresponding to the center of the projection of the ball on column 3 at the moment tj.

Here, the height h is calculated by the formula

h, i (pd,

where and, cm is the distance between the photocells in the columns. Upon further movement of the wave at time t, the i-, (i + 1) -, (i + 2) -th photocells of the column 4 are triggered and the output signals of the signal generator 9 are stopped using the OR 13 circuit and the coder 20 is coded and encoded 11 and are entered into the buffer register 15. On-demand access via interface 1 and 16 in computer 17, these codes allow to calculate the number of the photocell corresponding to the center of the projection of the ball on the wheel 4 at time 1 :,

.,, 1 + (i + 1) + (i + 2) lUj; 2

and determine the height h, i (t),

Determining the time intervals (t - t), (t - t,), (t3 - t) and counting the speed of the ball in the time interval tj - t quasi-constant, calculate the height of the ball at the moment of impact from the expression

M,

 hiitj-t) (ti-t)

h

In order to improve the accuracy of the measurement, measure the height of the ball at one point of its trajectory above the grid and the time of the passage of the ball at that point, then measure the height of the passage of the ball at the other, successively located point of the flight trajectory of the ball and time cha at this point, and the distance between the measuring points is chosen less than the diameter of the ball, and the height mcl at the moment of impact is determined by the following relation

where H is the height of the top edge of the net: The application of the proposed method for determining the height of m Cha at the moment of hitting the volleyball player during the training session improves the accuracy and height of the kick that will reduce the likelihood of blocking the ball by the defender and increase the effectiveness of the athlete's game actions.

Claims (1)

Invention Formula ; The method of determining the height of the ball at the moment of hitting it in volleyball, which consists in fixing the time of the athlete’s contact with him, 15 } i.) (.) Sz - H g; where hj ht t. t l - height of m cha; - the height of the ball over the grid in one of the points of its trajectory; - time passing m at height - the height of the ball above the grid in another, consistently located point of the path of the ball; flight time time of contact with the athlete. .7 12 sixteen 17