CN113713360B - Volleyball hitting counting method and device - Google Patents
Volleyball hitting counting method and device Download PDFInfo
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Abstract
The invention provides a volleyball hitting counting method and device, and belongs to the technical field of physical training. The method solves the problems that the prior art cannot be widely used and the misjudgment rate is high. The volleyball hitting counting method comprises the following steps: acquiring a triaxial acceleration signal through an acceleration sensor arranged in a volleyball body; carrying out vector superposition calculation on the collected triaxial acceleration signals to obtain a vector mode signal of each sampling point; respectively carrying out difference calculation on the vector mode signal of the next sampling point and the vector mode signal of the previous sampling point to obtain a differential vector mode signal of each sampling point; performing binary conversion on the differential vector mode signal of each sampling point in a threshold judgment mode to obtain a binary differential vector mode signal; and analyzing the binary difference vector mode signal by using a finite-state machine model to judge whether the ball is a sweet shot or not and recording the number of the sweet shots. A volleyball shot counting apparatus is also provided. The invention can improve the accuracy of volleyball hitting counting.
Description
Technical Field
The invention belongs to the technical field of physical exercise, and relates to a volleyball hitting counting method and device.
Background
The self-cushioned ball is one of basic techniques of volleyball sports, and is a ball hitting technique which enables an incoming ball to bounce off a cushioned hitting surface through the attack action of arms on the basis of the coordinated force of the whole body.
At present, in sports teaching and sports examinations of a plurality of provinces and cities in China, volleyball is one of teaching and examination items, and in the self-volleyball examination, a student is required to hit volleyball to a specific height to be qualified and counted, so that the fairness and justness of the self-volleyball test cannot be guaranteed by means of a visual inspection method. To solve this problem, the current scheme for counting the number of hit balls on the market mainly includes the following two categories:
(1) shot count based on machine vision methods
The method uses camera equipment to record the position of a volleyball in the batting process, calculates the movement track of a ball by using methods such as difference shadow and convolutional neural network, and judges that the batting is effective when the movement height of the ball reaches a set threshold value.
(2) Pressure sensor based shot counting
The method takes the batting behavior as a judgment target and takes the drastic change of the internal pressure of the ball body at the batting moment as a main characteristic.
Although the above two types of solutions enable the counting of volleyball shots, the following drawbacks still exist:
for the first category of solutions, this category of methods often places strict requirements on the lighting of the hitting field, the background and the costume of the player, which is peculiar to machine vision-based methods, and the equipment is bulky and costly. Obviously, the method is difficult to be used as a popular hit ball counting means for the masses.
For the second category of solutions, there are significant drawbacks to this category: there is a certain difficulty in defining non-hitting behavior (e.g., it is impossible to accurately identify whether a normal shot is taken, or a kick or a racket is taken), and therefore the misjudgment rate is high.
Disclosure of Invention
The invention aims to provide a volleyball hitting counting method and device aiming at the problems in the prior art, and the technical problems to be solved are as follows: how to improve the accuracy of volleyball hitting count.
The purpose of the invention can be realized by the following technical scheme: a volleyball shot count method, comprising the steps of:
A. acquiring a triaxial acceleration signal through an acceleration sensor arranged in a volleyball body;
B. carrying out vector superposition calculation on the collected triaxial acceleration signals to obtain a vector mode signal of each sampling point;
C. respectively carrying out difference calculation on the vector mode signal of the next sampling point and the vector mode signal of the previous sampling point to obtain a differential vector mode signal of each sampling point;
D. performing binary conversion on the differential vector mode signal of each sampling point in a threshold judgment mode to obtain a binary differential vector mode signal;
E. and analyzing the binary difference vector mode signal by using a finite-state machine model to judge whether the ball is a sweet shot or not and recording the number of the sweet shots.
The student is when carrying out volleyball pedestal training or examination, when the volleyball was hit, the acceleration sensor who sets up in the volleyball spheroid gathers the signal of spheroid motion process, the signal that acceleration sensor gathered mainly has x axle acceleration signal, y axle acceleration signal, z axle acceleration signal, because the spheroid has random roll phenomenon at hitting the in-process, unable use specific axle acceleration signal analysis spheroid motion characteristic, consequently, carry out the vector stack calculation and then obtain the vector mode signal of every sampling point with the triaxial acceleration signal of gathering, wherein every sampling point indicates: in the acceleration signal sampling process, the time point of each acceleration signal sampled in each second is named as a sampling point. When the ball body is completely separated from the arm of a player, the ball body enters an air stagnation state, and in order to avoid the problem that the ball hitting skills are different, the ball body rotates in the air stagnation process and the judgment of vector mode signals is influenced, and the problem that the peak of the vector mode signals and the ball hitting signals caused by non-ball hitting behaviors are similar and difficult to distinguish is solved, the vector mode signals of the next sampling point and the vector mode signals of the previous sampling point are subjected to difference calculation to obtain the difference vector mode signals of each sampling point. And finally, analyzing the binary differential vector mode signals by using a finite state machine model, judging whether the shot is a valid shot according to the number of 1 values and the number of 0 values of the binary differential vector mode signals, and recording the number of the valid shots when the shot is the valid shot. The invention uses differential acceleration as the movement process of the ball, greatly reduces the possibility that the ball is mistakenly identified as the hitting action in the high-speed movement and rolling state, and in addition, the finite-state machine model is used for counting the hitting number, so that most behaviors irrelevant to hitting can be eliminated, and the accuracy of volleyball hitting counting is effectively improved.
In the above-mentioned volleyball shot counting method, in the step B, the formula for vector-superimposing the acquired three-axis acceleration signals is as follows:
in the formula, a x (n) x-axis acceleration signal a of nth sampling point acquired by acceleration sensor y (n) is the y-axis acceleration signal of the nth sampling point acquired by the acceleration sensor, a z (n) acquiring a z-axis acceleration signal of an nth sampling point by the acceleration sensor; and a (n) is a vector mode signal of the nth sampling point, and n is the number of sampling points and takes a positive integer.
In the above-mentioned volleyball shot counting method, in the step C, the formula for calculating the difference between the vector mode signal of the next sampling point and the vector mode signal of the previous sampling point is as follows:
y(n)＝a(n)-a(n-1)
wherein, y (n) is the differential vector mode signal of the nth sampling point; a (n) is the vector mode signal of the nth sampling point; a (n-1) is a vector mode signal of the (n-1) th sampling point; n is the number of sampling points and is a positive integer.
In the above volleyball shot counting method, in the step D, the definition of binary conversion of the differential vector mode signal of each sampling point in a threshold decision manner is as follows:
in the formula, y th Is a set threshold value; b (n) is the binary difference vector mode signal of the nth sampling point; y (n) is the differential vector mode signal of the nth sampling point; n is the number of sampling points, and a positive integer is taken.
When the binary conversion is carried out, firstly, the differential vector mode signal y (n) is compared with the threshold value y th By comparison, at y (n) is greater than or equal to y th Then, the differential vector mode signal y (n) of the sampling point is converted into a binary differential vector mode signal b (n) of '1'; in y (n) is less than y th Then, the differential vector mode signal y (n) of this sampling point is converted into a binary differential vector mode signal b (n) of "0". In this way, canCan be lower than y th Any interference of (2) is removed, and the misjudgment probability of the non-batting behavior is reduced.
In the above volleyball shot counting method, before performing the operation of step E, the method further includes:
performing forward expansion processing on the binary difference vector modulus signal b (n) obtained in the step D, wherein the operation is as follows:
setting a binary differential vector mode signal B (N) as a boolean function defined on (0, 1, …, N-1) B, where B is a set of sampling points and N is a total number of sampling points;
setting a structural element S (M) as a Boolean function defined on S ═ 0, 1, …, M-1, wherein S is a forward expansion point set, M is the total number of forward expansion points, and M is less than N;
binary differential vector mode signal b (n) forward-dilated by s (m)
The formula of (1) is:
wherein,
v represents a logical or for the sign of the forward expansion. Wherein, M can be independently adjusted according to the material of the sphere and the use condition, and can take a value of 7. The binary differential vector mode signal processed by the method has fewer burrs, and the probability of misjudgment is greatly reduced.
In the above-mentioned volleyball shot counting method, in the step E, the operation of analyzing the binary difference vector mode signal using a finite state machine model to determine whether the shot is a sweet shot includes:
entering an initial S0 state of the finite-state machine model;
when the binary difference vector mode signal b (n) is 1, entering the state of S1 of the finite-state machine model, counting the number of b (n) continuously 1 in the state of S1, and recording the number as C1;
when C1 is within the preset batting range value and the binary difference vector mode signal b (n) is 0, the finite-state machine model jumps to the S2 state from the S1 state, and the number of b (n) continuously 0 is counted and recorded as C2;
when C2 is within the preset idling range value, the ball is judged to be hit effectively, the finite-state machine model jumps to the S3 state from the S2 state, the ball hitting action is counted, the initial S0 state of the finite-state machine model is returned, and the counting of the next ball hitting action is continued.
The counting number of the 1 value in the batting process and the counting number of the 0 value in the emptying process are set for judgment, whether batting action is effective batting or not can be effectively judged, most behaviors irrelevant to batting are effectively eliminated, and the accuracy of the volleyball technology is improved.
In the volleyball shot count method described above, the operation of determining a hit ball includes:
when the condition that C1 is within the preset hitting range value and C2 is within the preset emptying range value is met for the first time, the hitting times are accumulated, when the number of continuous hitting is larger than or equal to the preset hitting number, effective hitting is judged, then the number of continuous hitting is continuously accumulated and counted, and otherwise, when the number of continuous hitting is smaller than the preset hitting number, the continuous hitting number signal is discarded. The judgment condition of the continuous batting behavior in the first batting judgment process is set, the probability of wrong judgment can be reduced to be less than one in a thousand, and the accuracy of volleyball batting counting is further ensured.
In the above volleyball shot count method, the preset shot range value is set by the following equation:
W 1 ＝[f D min{T hit }-β，f D max{T hit }+β]
wherein, W 1 To preset a striking range value, T hit Max { T } for the duration of the stroke hit Denotes a plurality of T hit Min { T } of the largest number hit Denotes a plurality of T hit Smallest of the figures, f D Is the data output rate of the acceleration sensor, and beta is a compensation parameterAnd (4) counting.
A preset hitting range value W1 for setting the duration T of the hitting process hit Minimum and maximum values of the number of the 1 values of the intermediate binary differential vector modulus signal, T hit Obtained according to experimental analysis, in addition, a compensation parameter beta is introduced, the influence of acceleration difference and forward expansion can be effectively eliminated, and in the process of continuously counting the hit balls, T can be influenced hit The value is updated, and the accuracy of the volleyball hitting counting is further improved.
In the volleyball shot counting method, the preset stagnation range value is set by the following equation:
wherein, W 2 For the preset idling range value, H is the height of the shot, max { H } represents the largest of the plurality of H numbers, min { H } represents the smallest of the plurality of H numbers, f D Alpha is a compensation parameter for the data output rate of the acceleration sensor.
A preset hitting range value W2 for setting the duration T in the process of staying empty hang The number of the 0 values of the medium-value and two-value differential vector mode signals is the minimum value and the maximum value, the numerical values of the 0 values are mainly related to the height H of the hit ball, the H is obtained according to experimental analysis, in addition, a compensation parameter alpha is introduced, the air resistance and the influence of forward expansion can be effectively eliminated, in the process of continuously counting the hit balls, the H value can be updated, and the accuracy of the volleyball hit counting is further improved.
The utility model provides a volleyball batting counting assembly, is including setting up the microcontroller in the volleyball spheroid and all with the wireless data transmission module of microcontroller connection and the acceleration sensor who is used for gathering the triaxial acceleration signal of volleyball batting in-process, microcontroller includes:
the signal receiving module is used for receiving a three-axis acceleration signal acquired by the acceleration sensor;
the signal processing module is used for carrying out vector superposition calculation on the received triaxial acceleration signals so as to obtain a vector mode signal of each sampling point, and then carrying out difference calculation on the vector mode signal of each sampling point and the vector mode signal of the previous sampling point respectively so as to obtain a differential vector mode signal of each sampling point;
the signal conversion module is used for performing binary conversion on the differential vector mode signal of each sampling point in a threshold judgment mode to obtain a binary differential vector mode signal;
the signal judging and counting module is used for analyzing the binary difference vector mode signal by using a finite-state machine model to judge whether the ball is a valid ball and record the number of the valid balls;
and the output module is used for transmitting the effective batting quantity to a client outside the sphere through the wireless data transmission module.
When a student carries out volleyball training or examination and when a volleyball is hit, an acceleration sensor arranged in a volleyball body collects signals of the motion process of the volleyball body, the signals collected by the acceleration sensor mainly comprise an x-axis acceleration signal, a y-axis acceleration signal and a z-axis acceleration signal, because the random rolling phenomenon exists in the striking process of the ball body, the acceleration signal of a specific axis cannot be used for analyzing the motion characteristics of the ball body, therefore, the microcontroller processes the acquired triaxial acceleration signal, receives the triaxial acceleration signal through a signal receiving module in the microcontroller, vector superposition calculation is carried out on the received triaxial acceleration signals through a signal processing module so as to obtain a vector mode signal of each sampling point, and then difference calculation is carried out on the vector mode signal of each sampling point and the vector mode signal of the previous sampling point respectively so as to obtain a differential vector mode signal of each sampling point; when the ball body is completely separated from the arm of a player, the ball body enters a dead space state, and in order to avoid the problem that the ball body rotates in the dead space process and the judgment of vector mode signals is influenced in the process of dead space and the problem that the peak of the vector mode signals and the hitting signals are similar and difficult to distinguish caused by non-hitting behaviors, the vector mode signals of each sampling point and the vector mode signals of the previous sampling point are subjected to difference calculation to obtain the difference vector mode signals of each sampling point. And finally, the signal judging and counting module analyzes the binary differential vector mode signals by using a finite state machine model, judges whether the shot is effective according to the number of 1 values and the number of 0 values of the binary differential vector mode signals, records the number of the effective shot when the shot is effective, and transmits the effective shot to the wireless data transmission module through the output module, and the wireless data transmission module performs data interaction with a sphere external client so as to ensure that an examiner or a teacher can timely know the number of the volleyball shots of the students. The invention uses differential acceleration as the movement process of the ball, greatly reduces the possibility that the ball is mistakenly identified as the hitting action in the high-speed movement and rolling state, and in addition, the finite-state machine model is used for counting the hitting number, so that most behaviors irrelevant to hitting can be eliminated, and the accuracy of volleyball hitting counting is effectively improved.
In the above-mentioned volleyball batting counting assembly, the signal is judged and the count module includes:
the signal counting submodule is used for recording the hitting times and performing accumulated counting on the hitting times to obtain an accumulated hitting time value by utilizing a finite state machine model when the continuous number of the binary differential vector mode signals of 1 is judged to be within a preset hitting range value and the continuous number of the binary differential vector mode signals of 0 is judged to be within a preset emptying range value;
and the signal judgment submodule is used for judging the first continuous hitting quantity recorded by the signal counting submodule, judging the first continuous hitting quantity to be effective hitting when the continuous hitting quantity is greater than or equal to the preset hitting quantity, controlling the signal counting submodule to continue to count the continuous hitting quantity in an accumulated mode, and otherwise discarding the continuous hitting quantity signal when the continuous hitting quantity is smaller than the preset hitting quantity. The signal judgment module is arranged to judge the continuous batting behavior in the first batting judgment process, effective batting is judged only when the number of continuous batting exceeds the preset batting number, and the probability of wrong judgment can be reduced to be less than one in a thousand by the setting, so that the accuracy of volleyball batting counting is further ensured.
Compared with the prior art, the volleyball hitting counting method and the volleyball hitting counting equipment have the advantages that:
1. the invention calculates the difference value of the front and rear sampling points of the vector mode signal of the acceleration, and uses the calculated differential vector mode signal, namely the differential acceleration as the signal of the movement process of the ball body, so that the possibility that the ball body is mistakenly identified as the ball hitting action in the high-speed movement and rolling state can be greatly reduced.
2. The invention utilizes the finite state machine model to count, and can eliminate most behaviors irrelevant to the hitting according to the accumulated dead space duration and hitting duration.
Drawings
Fig. 1 is a control flow chart according to a first embodiment of the present invention.
Fig. 2 is a control flow chart of the second embodiment of the present invention.
FIG. 3 is a state transition diagram of the finite state machine model of the present invention.
Fig. 4 is a schematic structural diagram of the present invention.
In the figure, 1, a microcontroller; 11. a signal receiving module; 12. a signal processing module; 13. a signal conversion module; 14. a signal judging and counting module; 14a, a signal counting submodule; 14b, a signal judgment submodule; 15. an output module; 2. an acceleration sensor; 3. and a wireless data transmission module.
Detailed Description
The following are specific embodiments of the present invention and are further described with reference to the drawings, but the present invention is not limited to these embodiments.
The first embodiment is as follows:
as shown in figure 1, the volleyball shot counting method is used for counting volleyball shots, and firstly, three-axis acceleration signals are collected through an acceleration sensor 2 arranged in a volleyball body, wherein the three-axis acceleration signals comprise a x 、a y And a z Acquiring the motion state of the volleyball ball body through a triaxial acceleration signal; then, vector superposition calculation is carried out on the acquired triaxial acceleration signals to obtain a vector mode signal of each sampling point, the vector mode signal of each sampling point is obtained by carrying out vector superposition calculation through the following formula:
in the formula, a x (n) x-axis acceleration signal a of the nth sampling point collected by the acceleration sensor 2 y (n) is the y-axis acceleration signal a of the nth sampling point collected by the acceleration sensor 2 z (n) is a z-axis acceleration signal of the nth sampling point acquired by the acceleration sensor 2; and a (n) is a vector modulus signal of the nth sampling point, n is the number of the sampling points, and a positive integer is taken, such as 1, 2, 3.
After the vector mode signal a (n) of each sampling point is obtained, the vector mode signal a (n) of the next sampling point is respectively subjected to difference calculation with the vector mode signal a (n-1) of the previous sampling point to obtain a differential vector mode signal b (n) of each sampling point; the differential vector mode signal y (n) is obtained by performing difference calculation according to the following formula:
y(n)＝a(n)-a(n-1)
where y (n) is the differential vector mode signal for each sample point; a (n) is a vector mode signal of each sampling point; a (n-1) is a vector mode signal of a previous sampling point; n is the number of sampling points and is a positive integer.
For the practice of hitting a ballThe peak value range of the differential vector mode signal is distributed between 8g and 26g, and the DSVM peak value distribution of most small non-batting behaviors is mainly concentrated below 10 g. At this time, the proper y is selected th Making the differential vector mode signal y (n) undergo binary conversion, defined as:
in the formula, y th Is a set threshold value; b (n) is a binary differential vector mode signal of the nth sampling point, and the signal has two values of 0 and 1; y (n) is the differential vector mode signal of the nth sampling point; n is the number of sampling points and is a positive integer. The binary conversion is carried out by the threshold judgment mode, and the value lower than y can be filtered th The differential vector mode signal plays a role in reducing the misjudgment probability of the non-batting behavior, y th The value is 9-12 according to different ball materials, and the value is obtained according to experiments.
In order to remove the influence of the burr on the binary difference vector mode signal, the binary difference vector mode signal is subjected to forward expansion processing, and the operation is as follows:
setting a binary differential vector mode signal B (N) as a boolean function defined on B ═ (0, 1, …, N-1), where B is a set of sampling points and N is a total number of sampling points;
setting a structural element S (M) as a Boolean function defined on S ═ 0, 1, …, M-1, wherein S is a forward expansion point set, M is the total number of forward expansion points, and M is less than N;
binary differential vector mode signal b (n) forward-dilated by s (m)
The formula of (1) is:
wherein,
for the notation of forward dilation, V denotes a logical or, e.g., 0V 0-0, 0V 1-1, 1V 0-1, 1V 1-1. In this embodiment, M is 7.
For example, the set of b (n) is (1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 1, 1, 1, 0, 0, 0, 1, 1, 1, 0, 0, ·);
b (n) is forward expanded by s (m)
The resulting set is (1, 1, 1, 1, 1, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, h).
After the binary differential vector mode signal b (n) is subjected to expansion processing, the value of the binary differential vector mode signal 1 reflects the striking process, and the duration of the striking process is T hit (ii) a The binary differential vector modulo signal 0 value reflects the blanking process and has a duration of T hang . If the data output rate of the MEMS acceleration sensor 2 is f D That is, the output fd data can be collected in one second, and the preset hitting range value W1, W1 describe T hit The number range of the values of the period 1 can be expressed by an expression (1), and the influence of acceleration difference and forward expansion is eliminated by introducing a compensation parameter beta.
W 1 ＝[f D min{T hit }-β，f D max{T hit }+β] (1)
Wherein, W 1 To preset a hitting range value, T hit Max { T } T, duration of the stroke hit Denotes a plurality of T hit Min { T } of the largest number hit Denotes a plurality of T hit Smallest of the figures, f D Is the data output rate of the acceleration sensor 2, and β is the compensation parameter.
Presetting a dead space range value W2, W 2 Is also a range value describing T hang The range of 0 values of the duration can be represented by formula (2), where H is the set of heights of shots that represent the heights of shots that meet the specification. A compensation parameter a is introduced to eliminate the effects of air resistance and forward expansion.
Wherein, W 2 For the preset idling range value, H is the height of the shot, max { H } represents the largest of the plurality of H numbers, min { H } represents the smallest of the plurality of H numbers, f D α is a compensation parameter, which is a data output rate of the acceleration sensor 2.
Thus, at T hit The number of the period 1 values lies in the range of W1 and T hang When the number range of the period 0 values is within the range of W2, it can be regarded as a hit ball, in this embodiment, as shown in fig. 3, the finite state machine model is used to analyze the binary difference vector mode signal to determine whether the hit ball is a hit ball, specifically:
entering an initial S0 state of the finite-state machine model, waiting for the binary difference vector mode signal b (n) to be 1, entering an S1 state of the finite-state machine model when b (n) is 1, counting the number of b (n) which are continuously 1 in the S1 state, recording as C1, judging whether C1 is positioned within a preset batting range value W1 when the binary difference vector mode signal b (n) is 0, and if C1 is positioned within a preset batting range value W1 1 ∈W 1 When the finite-state machine model jumps from the S1 state to the S2 state, the number of b (n) which is continuously 0 is counted and recorded as C2, when the binary difference vector mode signal b (n) is 1, whether the C2 is located in the preset dead space range value W2 is judged, when the C2 is located in the preset dead space range value, a valid batting is judged, the finite-state machine model jumps from the S2 state to the S3 state, the batting action is accumulated to be counted to q, the initial S0 state of the finite-state machine model is returned, and the batting action of the next time is continuously counted. If it is
When the temperature of the water is higher than the set temperature,
representing signals that do not belong to, are not in the set, the finite state machine model returns to the initial S0 state, or if so
Then the finite-state machine model returns to the initial state of S0 and waits for the next binary differential vector modulo signal 1 value to appear.
Variable parameter y th Alpha and beta can be adjusted independently according to the material and use condition of the sphere, in this embodiment, y th ＝10、α＝3.3、β＝3。
As shown in fig. 4, the volleyball hitting counting device comprises a microcontroller 1 arranged in a volleyball body, a wireless data transmission module 3 connected with the microcontroller 1, and an acceleration sensor 2 used for acquiring triaxial acceleration signals in the volleyball hitting process, wherein the microcontroller 1 comprises:
the signal receiving module 11 is used for receiving a triaxial acceleration signal acquired by the acceleration sensor 2;
the signal processing module 12 is configured to perform vector superposition calculation on the received triaxial acceleration signal to obtain a vector mode signal of each sampling point, and then perform difference calculation on the vector mode signal of each sampling point and a vector mode signal of a previous sampling point to obtain a differential vector mode signal of each sampling point;
the signal conversion module 13 is configured to perform binary conversion on the differential vector mode signal of each sampling point in a threshold decision manner to obtain a binary differential vector mode signal;
the signal judging and counting module 14 is used for analyzing the binary difference vector mode signal by using a finite-state machine model to judge whether the ball is a sweet shot or not and recording the number of the sweet shots;
and the output module 15 is used for transmitting the effective batting quantity to a client outside the ball body through the wireless data transmission module 3.
The signal judging and counting module 14 includes:
the signal counting sub-module 14a is used for recording the hitting times and performing accumulated counting on the hitting times to obtain an accumulated hitting time value by utilizing a finite state machine model when the continuous number of the binary differential vector mode signals of 1 is judged to be within a preset hitting range value and the continuous number of the binary differential vector mode signals of 0 is judged to be within a preset stagnation range value;
and the signal judgment submodule 14b is used for judging the first continuous hitting quantity recorded by the signal counting submodule 14a, judging the continuous hitting as an effective hitting when the continuous hitting quantity is greater than or equal to the preset hitting quantity, controlling the signal counting submodule 14a to continuously count the continuous hitting quantity in an accumulated manner, and otherwise discarding the continuous hitting quantity signal when the continuous hitting quantity is smaller than the preset hitting quantity.
The acceleration sensor 2 is a MEMS acceleration sensor 2.
The wireless data transmission module 3 adopts a Wi-Fi module, a Bluetooth module or 4G/5G data.
When the volleyball hitting counting equipment counts volleyball hitting, counting is carried out through the volleyball hitting counting method, the counting principle is already described in the volleyball hitting counting method, and the description is omitted here. When obtaining the volleyball hitting quantity of each student through this volleyball counting assembly, can hit the transmission of volleyball hitting quantity to spheroid outside client through wireless data transmission module 3, carry out data interaction with spheroid outside client, obtain every student volleyball hitting quantity, this equipment strong adaptability satisfies volleyball hitting count demand under the multiple occasion, can effectively distinguish batting action and non-batting action moreover, if the action of playing the ball with the foot.
Example two:
as shown in fig. 2, the technical solution in the present embodiment is substantially the same as that in the first embodiment, except that c is satisfied once 1 ∈W 1 ∧c 2 ∈W 2 And is not the case for a sweet shot. Therefore, the following operations are also performed in the S3 state of the finite-state machine model:
at the first decision c 1 ∈W 1 ∧c 2 ∈W 2 When the number of the continuous effective batting in the state is accumulated, if the number of the continuous batting is more than or equal to the preset batting number q 0 Then, receive q 0 I.e. q 0 On the basis of (a) thereafter satisfying c 1 ∈W 1 ∧c 2 ∈W 2 When the golf is played, the golf is regarded as effective batting and accumulated into q, and if the continuous batting quantity is less than the preset batting quantity q 0 The consecutive hit number signal is discarded. Due to q 0 Will affect the recognition accuracy when the number of hit balls is small, q in actual use 0 Typically no greater than 4. When q is 0 When the value is 4, the misjudgment probability is lower than 1 per mill.
The specific embodiments described herein are merely illustrative of the spirit of the invention. Various modifications or additions may be made to the described embodiments or alternatives may be employed by those skilled in the art without departing from the spirit or ambit of the invention as defined in the appended claims.
Claims (8)
1. A volleyball shot counting method is characterized by comprising the following steps:
A. acquiring a triaxial acceleration signal through an acceleration sensor (2) arranged in a volleyball body;
B. carrying out vector superposition calculation on the collected triaxial acceleration signals to obtain a vector mode signal of each sampling point; the formula for vector superposition of the acquired triaxial acceleration signals is as follows:
in the formula, a x (n) is an x-axis acceleration signal a of the nth sampling point acquired by the acceleration sensor (2) y (n) is the y-axis acceleration signal a of the nth sampling point collected by the acceleration sensor (2) z (n) is a z-axis acceleration signal of the nth sampling point acquired by the acceleration sensor (2); a (n) is a vector mode signal of an nth sampling point, n is the number of sampling points, and a positive integer is taken;
C. calculating the difference value of the vector mode signal a (n) of the next sampling point and the vector mode signal a (n-1) of the previous sampling point to obtain a differential vector mode signal y (n) of each sampling point;
D. performing binary conversion on the differential vector mode signal y (n) of each sampling point in a threshold judgment mode to obtain a binary differential vector mode signal b (n);
E. analyzing the binary difference vector mode signals b (n) by using a finite-state machine model to judge whether the golf is a hit ball or not and recording the number of hit balls; the operation of determining whether the ball is a sweet spot includes:
entering an initial S0 state of the finite-state machine model;
when the binary difference vector mode signal b (n) is 1, entering the state of S1 of the finite-state machine model, counting the number of b (n) continuously 1 in the state of S1, and recording the number as C1;
when C1 is within the preset batting range value and the binary difference vector mode signal b (n) is 0, the finite-state machine model jumps to the S2 state from the S1 state, and the number of b (n) continuously 0 is counted and recorded as C2;
when C2 is within the preset idling range value, the ball is judged to be hit effectively, the finite-state machine model jumps to the S3 state from the S2 state, the ball hitting action is counted, the initial S0 state of the finite-state machine model is returned, and the counting of the next ball hitting action is continued.
2. The volleyball shot counting method of claim 1, wherein in the step C, a formula for calculating a difference between the vector mode signal of the subsequent sample point and the vector mode signal of the previous sample point is as follows:
y(n)＝a(n)-a(n-1)
wherein, y (n) is the differential vector mode signal of the nth sampling point; a (n) is a vector mode signal of the nth sampling point; a (n-1) is a vector mode signal of the (n-1) th sampling point; n is the number of sampling points and is a positive integer.
3. The volleyball shot counting method according to claim 2, wherein in the step D, binary conversion of the differential vector mode signal of each sampling point by a threshold decision method is defined as:
in the formula, y th Is a set threshold value; b (n) is the binary difference vector mode signal of the nth sampling point; y (n) is the differential vector mode signal of the nth sampling point; n is the number of sampling points and is a positive integer.
4. The volleyball shot counting method of claim 3, further comprising, before performing the operation of step E:
performing forward expansion processing on the binary difference vector modulus signal b (n) obtained in the step D, wherein the operation is as follows:
setting a binary differential vector mode signal B (N) as a boolean function defined on B ═ (0, 1, …, N-1), where B is a set of sampling points and N is a total number of sampling points;
setting a structural element S (M) as a Boolean function defined on S ═ 0, 1, …, M-1, wherein S is a forward expansion point set, M is the total number of forward expansion points, and M is less than N;
binary differential vector mode signal b (n) forward-dilated by s (m)
The formula of (1) is:
wherein,
the V-shaped represents a logical "OR" for the sign of the forward expansion.
5. The volleyball shot counting method of claim 1, wherein the operation of determining a hit ball includes:
when the condition that C1 is within the preset hitting range value and C2 is within the preset emptying range value is met for the first time, the hitting times are accumulated, when the number of continuous hitting is larger than or equal to the preset hitting number, effective hitting is judged, then the number of continuous hitting is continuously accumulated and counted, and otherwise, when the number of continuous hitting is smaller than the preset hitting number, the continuous hitting number signal is discarded.
6. The volleyball shot count method of claim 5, wherein the preset shot range value is set by the following equation:
W 1 ＝[f D min{T hit }-β，f D max{T hit }+β]
wherein, W 1 To preset a hitting range value, T hit Max { T } T, duration of the stroke hit Denotes a plurality of T hit Min { T } of the largest number hit Denotes a plurality of T hit Smallest of the figures, f D The data output rate of the acceleration sensor (2) is beta, and the beta is a compensation parameter;
the preset stagnation range value is set by the following formula:
wherein, W 2 For the preset idling range value, H is the height of the shot, max { H } represents the largest of the plurality of H numbers, min { H } represents the smallest of the plurality of H numbers, f D Is the data output rate of the acceleration sensor (2), and alpha is a compensation parameter.
7. The utility model provides a volleyball hits ball counting equipment which characterized in that, including setting up microcontroller (1) in the volleyball spheroid and all with microcontroller (1) be connected wireless data transmission module (3) and be used for gathering the acceleration sensor (2) that the volleyball hit the triaxial acceleration signal of ball in-process, microcontroller (1) includes:
the signal receiving module (11) is used for receiving the three-axis acceleration signals acquired by the acceleration sensor (2);
the signal processing module (12) is used for performing vector superposition calculation on the received triaxial acceleration signals to obtain a vector mode signal of each sampling point, then performing difference calculation on the vector mode signal of each sampling point and a vector mode signal of a previous sampling point to obtain a differential vector mode signal of each sampling point, and performing vector superposition on the acquired triaxial acceleration signals according to the following formula:
in the formula, a x (n) is the x-axis acceleration signal a of the nth sampling point collected by the acceleration sensor (2) y (n) is the y-axis acceleration signal a of the nth sampling point collected by the acceleration sensor (2) z (n) is a z-axis acceleration signal of the nth sampling point acquired by the acceleration sensor (2); a (n) is a vector mode signal of an nth sampling point, n is the number of sampling points, and a positive integer is taken;
the signal conversion module (13) is used for carrying out binary conversion on the differential vector mode signal of each sampling point in a threshold judgment mode to obtain a binary differential vector mode signal;
a signal judging and counting module (14) for analyzing the binary difference vector mode signal by using a finite state machine model to judge whether the ball is a hit ball and recording the number of hit balls, wherein the operation of judging whether the ball is a hit ball comprises the following steps:
entering an initial S0 state of the finite-state machine model;
when the binary difference vector mode signal b (n) is 1, entering the state of S1 of the finite-state machine model, counting the number of b (n) continuously 1 in the state of S1, and recording the number as C1;
when C1 is within the preset batting range value and the binary difference vector mode signal b (n) is 0, the finite-state machine model jumps to the S2 state from the S1 state, and the number of b (n) continuously 0 is counted and recorded as C2;
when C2 is within the preset emptying range value, judging that the ball is hit effectively, jumping to the S3 state from the S2 state by the finite state machine model, counting the ball hitting action, returning to the initial S0 state of the finite state machine model, and continuing to count the next ball hitting action;
and the output module (15) is used for transmitting the effective batting quantity to a client outside the sphere through the wireless data transmission module (3).
8. A volleyball shot count device according to claim 7, wherein the signal determination and count module (14) includes:
the signal counting submodule (14a) is used for recording the hitting times and performing accumulated counting on the hitting times to obtain an accumulated hitting time value by utilizing a finite state machine model when the continuous number of the binary differential vector mode signals of 1 is judged to be within a preset hitting range value and the continuous number of the binary differential vector mode signals of 0 is judged to be within a preset emptying range value;
and the signal judgment sub-module (14b) is used for judging the first continuous hitting quantity recorded by the signal counting sub-module, judging the continuous hitting as an effective hitting when the continuous hitting quantity is greater than or equal to the preset hitting quantity, controlling the signal counting sub-module to continuously count the continuous hitting quantity in an accumulated mode, and otherwise discarding the continuous hitting quantity signal when the continuous hitting quantity is smaller than the preset hitting quantity.
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