RU2529760C1 - Method to measure engaged mass of sportsman in process of movement actions and device for its realisation - Google Patents

Abstract

FIELD: instrumentation.

SUBSTANCE: sportsman makes two identical movement actions. Using a spectrum analyser, they measure acceleration of the arm, on which a piezoaccelerometer is fixed. A calibrated weight is additionally suspended on the arm of the sportsman, where the piezoaccelerometer is fixed. Using two produced values of arm acceleration and the available mass of the additional weight, a sought for value is found. A simulator to measure engaged mass of the sportsman, for instance, a skier, represents a rectangular frame, on short sides of which in parallel to each other there are fixed shafts installed, on the ends of which with the help of rolling bearings there are steel bobbins placed, having a cylindrical shape. Reinforced rubber tapes are pulled onto each pair of bobbins along the long sides of the frame. In the central part of the structure, closer to one of the shafts, there is a site welded, on which the skier stands and pushes using ski poles and rotating it.

EFFECT: increased accuracy of measurements.

2 cl, 6 dwg

Description

The invention relates to measuring equipment, in particular to means of objective control of an athlete’s individual physical data, and can be used in a wide variety of sports, such as skiing.

Any motor action of an athlete is characterized by the magnitude of the applied force. The relationship between force, mass and acceleration is determined by Newton’s second law.

, $$F=M\cdot a\left(\text{one}\right)$$

,

where F is the force [Newton], M is the mass [kg], and is the linear acceleration of the object of application of force (arms or legs) [m / s ² ].

For example, in skiing, when pushing away with sticks and at the same time, the athlete exerts a force proportional to his body weight and acceleration [1].

However, it is not known how to determine the effort that he needs to spend.

The closest in technical essence to the claimed invention is the measurement of acceleration using an acceleration sensor - a piezoceramic accelerometer (PA), which is attached to the place of application of the motor force of the skier (in this case, to the arm or leg) [2]. The piezoceramic accelerometer, in turn, is connected to a spectrum analyzer with replaceable RC filters.

However, in addition to measuring the developed acceleration, it is also necessary to know the mass of the object of applied force. Currently, this parameter is being replaced by the parameter "number of movements"

, $$I=m\cdot v\left(\text{2}\right)$$

,

where v is the speed of the arm, and m is the mass of the arm, which is assumed to be equal to four or more kg. Therefore, the main disadvantage of the existing method for determining the magnitude of the applied force is the inability to calculate the mass involved in the movement process. In addition, the acceleration meter itself is cumbersome, has a large error, and with its help it is also impossible to control the actions of the athlete during the competition.

The objective of the invention is to determine the size of the involved mass of the athlete when he performs motor actions, improving the quality of the training process, reducing the training time.

The problem is solved in that initially the acceleration of the object of the source of application of force a _{1 is} measured, then, with the same force, but with an additional known mass M at the same object on which the sensor is mounted, the acceleration a _{2 is} determined. The mass involved will be calculated by the formula

, $$X\cdot a_{\mathrm{one}}=\left(X+M\right)\cdot a_2\left(\text{3}\right)$$

,

where X is the athlete's mass involved. Transforming formula 3, we obtain

$$X=\frac{M\cdot a_2}{a_{\mathrm{one}}-a_2}\left(\text{four}\right)$$

From the measured values according to formula 4, the desired value of the athlete's involved mass is determined when he performs a motor action.

Figure 1 shows a diagram of a simulator for measuring the involved mass of an athlete while repulsing (pitchless) ski poles. The simulator is a rectangular frame, on whose short sides stationary shafts 1 are mounted parallel to each other. At the ends of these shafts, steel bobbins are mounted using rolling bearings 2. Reinforced rubber bands 3 of such width are stretched along the long sides of the frame, which would allow to close the entire surface of the bobbins. In the central part of the structure, closer to one of the shafts, a platform 4 is welded on which the skier 5 stands and is pushed away by sticks from the tape, leading it in a circular motion.

The block diagram of the measurement of the involved mass of the athlete is shown in figure 2.

The simulator for the athlete’s involved mass is indicated by the number 6, the piezo accelerometer, which is mounted on the athlete’s hand, by the number 7, the spectralizer with replaceable RC filters, by the number 8, the millivoltmeter, which serves as an indicator of the athlete’s hand acceleration in repulsion mode, by the number 9, the load calibrated by mass, equal to 1000 grams - the number 10.

A schematic diagram of a spectral analyzer with a PA connected to the input is presented in Fig. 3. R1; R2; C1; C2 - interchangeable radio components.

Examples of specific performance. A skier with a hand mass of 3.7 kg performs a series of 6-8 simultaneous repulsions on the simulator (Fig. 1) and thereby excites oscillations in the piezo-accelerometer, which is fixed to the wrist of one of his hands. The signal from the piezo-accelerometer is fed to the input of the spectral analyzer with replaceable RC filters and then to the millivoltmeter. The acceleration value is recorded in table 1. Then, a weight of 1000 grams in the form of a cuff is hung on the wrist on which the piezo-accelerometer is fixed, and a series of 6-8 repulsions is again repeated. The value of hand acceleration, but with an additional load, is also recorded in Table 1. By successively changing interchangeable RC filters in the spectral analyzer and repeating the same series of repulsions, they fill in the data in Table 1 of the acceleration in millivolts.

Table 1 (1.83-2.0) Hz (2.83-3.0) Hz (3.33-3.5) Hz (3.83-4.0) Hz (4.33-4.5) Hz (5.83-6.0) Hz (9.83-10.0) Hz b / g s / g b / g s / g b / g s / g b / g s / g b / g s / g b / g s / g b / g s / g 90 76 80 72 89 75 125 75 110 80 120 90 70 fifty x = 5.4 kg x = 9.0 kg x = 5.3 kg x = 1.5 kg x = 2.7 kg x = 3.0 kg x = 2.5 kg b / g - without cargo; s / g - with cargo.

Figure 4 shows a graphical display of the obtained spectrogram, from which it can be seen that with this repulsion technique, the insertion weight of the athlete's body (shaded on the graph) is present in the frequency range from 1.83 to 3.5 Hz, and then, at higher frequencies, repulsion occurs solely due to the strength of the muscles of the hands.

Figure 5 presents the appearance of the measuring device (a - assembled, b - disassembled form), figure 6 - method of mounting it directly on the skier.

The inventive method of measuring the involved mass of the athlete allows, in comparison with known methods, to obtain the true value of the mass of the athlete participating in the motor action.

Claims (2)

1. The method of determining the athlete’s involved mass when performing motor actions, which consists in measuring the accelerations of the object of application of force (arms or legs), characterized in that the measurements are carried out with the help of a spectral analyzer initially without an additionally calibrated mass, and then with the above cargo, the measured values of which determine the desired value. 2. The device for implementing the method according to claim 1, consisting of a piezoceramic accelerometer and a spectral analyzer with replaceable RC filters, characterized in that the piezoceramic acceleration sensor is attached to the athlete’s arm or leg, connected to a spectral analyzer and an indicator calibrated in units of acceleration, and calibrated by mass, the load with a piezo-accelerometer mounted on it is additionally hung when measuring acceleration again.

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