Self-adaptive serving control method for table tennis serving machine

Abstract

The invention discloses a self-adaptive serving control method for a table tennis serving machine, which relates to the technical field of serving equipment and comprises the following steps: calculating the running distance of a table tennis ball before return stroke according to serving time and return stroke time, acquiring first movement time and first sound wave time according to the distance, and acquiring actual running time before return stroke according to the two times; determining ball falling point time and calculating second motion time in combination with return stroke time; coordinates of a ball hitting point and a ball falling point and the running distance after return stroke are obtained, and the running speed and second sound wave time after return stroke are calculated in combination with the second movement time; according to the two times, actual operation time after return stroke is obtained; according to the actual running time before and after the return stroke, the serving time interval is obtained, the serving speed is determined, and self-adaptive serving control of the serving machine is achieved; real-time adjustment can be carried out according to the levels of different users, the pitching interval of the pitching machine is consistent with the round-trip time, the pitching speed is consistent with the return stroke speed, and the maximum training effect is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of ball serving equipment, and in particular to an adaptive ball serving control method for a table tennis ball serving machine. Background Art

[0002] With the development of technology and the systematization of athlete training, science and technology have gradually been integrated into athletes' daily training. For racket sports such as badminton, tennis, table tennis and other sports, the training method has gradually changed from manual training to automatic training with a ball-serving machine, thereby achieving the purpose of increasing training intensity and saving manpower. Existing ball-serving machines require manual adjustment of the height, speed and position of the ball-serving machine before serving. If the speed and time interval of the ball-serving need to be adjusted during training, it is necessary to stop and adjust manually. Moreover, it is often not possible to adjust to the value that achieves the training effect at one time. It is often necessary to adjust the value multiple times to achieve the ideal speed and interval. The ball-serving interval and speed of the ball-serving machine cannot be adjusted in real time according to the different users to match the training requirements of different users and achieve the best training effect. Summary of the Invention

[0003] The present invention provides an adaptive serving control method for a table tennis serving machine, so as to overcome the technical problem that the existing serving machine cannot adjust the serving interval and speed of the serving machine in real time according to different users to match the training requirements of different users and achieve the best training effect.

[0004] A table tennis serving machine adaptive serving control method, comprising:

[0005] S1: obtaining the serving time of the table tennis ball through the time detection device and obtaining the returning time of the table tennis ball through the second sound detection device;

[0006] S2: Calculating the distance the table tennis ball travels before the return, and obtaining a first motion time and a first sound wave time of the table tennis ball based on the distance before the return, wherein the first motion time is used to represent the time it takes for the table tennis ball to move from the serving point to the hitting point before the return, and the first sound wave time is used to represent the time it takes for sound to propagate between the serving point and the hitting point of the table tennis ball;

[0007] S3: obtaining the actual running time of the table tennis ball before hitting back according to the first movement time of the table tennis ball and the first sound wave time;

[0008] S4: Determine the ball landing point time by a third sound detection device, and calculate a second movement time of the table tennis ball based on the return time and the ball landing point time; the second movement time is used to represent the time it takes for the table tennis ball to move from the hitting point to the landing point;

[0009] S5: Obtaining the coordinates of the hitting point and the landing point of the table tennis ball, determining the distance traveled by the table tennis ball after the return according to the hitting point and the landing point coordinates, calculating the running speed of the table tennis ball after the return according to the running distance after the return and the second movement time of the table tennis ball; obtaining the actual running time of the table tennis ball after the return according to the second movement time and the second sound wave time; the second sound wave time is used to represent the time it takes for sound to propagate between the hitting point and the landing point of the table tennis ball;

[0010] S6: obtaining a time interval for the ball machine to serve based on the actual running time before the table tennis ball is hit back and the actual running time after the table tennis ball is hit back, and determining a serving speed of the ball machine based on the running speed of the table tennis ball after the table tennis ball is hit back;

[0011] S7: adjusting the serving mode of the ball serving machine in real time according to the time interval of serving and the serving speed of the ball serving machine, so as to realize adaptive serving control of the ball serving machine.

[0012] Furthermore, S2 calculates the running distance of the table tennis ball before the return, and obtains the first movement time and the first sound wave time of the table tennis ball according to the running distance before the return, including:

[0013] S21, obtaining the first movement time of the table tennis ball, as shown in formula (1),

[0014] T0 = T2 - T1 (1)

[0015] Wherein, T1 represents the actual time when the table tennis ball leaves the ball machine obtained by the time detection device, and T2 represents the return time obtained by the second sound detection device;

[0016] S22. A triangle is formed with the wide side of the table tennis table as the base, the distances between the third sound detection device and the first sound detection device and the hitting point of the table tennis ball as adjacent sides, and the second sound detection device and the time detection device as the midpoints. The midline theorem of the triangle is used to determine the distance the table tennis ball travels before hitting back, as shown in formula (2).

[0017]

[0018] in, represents the distance between the first sound detection device and the hitting point, Indicates the distance between the third sound detection device and the hitting point. represents the distance the ping-pong ball travels before being hit back, and c represents the wide side of the ping-pong table;

[0019] The relationship between the three sides of the triangle is constructed using the distances between the first sound detection device and the third sound detection device and the hitting point of the table tennis ball, as shown in formulas (3), (4) and (5).

[0020]

[0021] Substituting formulas (3), (4) and (5) into formula (2), we get formula (6):

[0022]

[0023] Wherein, k represents the distance difference between the distance between the first sound detection device and the hitting point and the distance between the third sound detection device and the hitting point, p represents the distance difference between the distance between the first sound detection device and the hitting point and the distance the table tennis ball travels before the return, and q represents the distance difference between the distance between the third sound detection device and the hitting point and the distance the table tennis ball travels before the return. k, p, q are shown in formulas (7), (8), and (9).

[0024] k=(T a -T b )*V s (7)

[0025] p=(T a -T2)*V s (8)

[0026] Q=(T b -T2)*V s (9)

[0027] Among them, T a represents the return strike time obtained by the first sound detection device, T b V represents the return strike time obtained by the third sound detection device; s represents the speed of sound;

[0028] S23. Obtain the time for the sound to propagate the running distance according to the running distance, as shown in formula (10):

[0029]

[0030] Among them, T s Indicates the time it takes for sound to travel a distance.

[0031] Furthermore, S3 obtains the actual running time before the table tennis ball is hit back according to the first movement time of the table tennis ball and the first sound wave time, including:

[0032] Get the actual running time before the table tennis ball is hit back, as shown in formula (11),

[0033] Tp1=T0-T s (11).

[0034] Furthermore, S4 determines the ball landing point time by a third sound detection device, and calculates the second movement time of the table tennis ball according to the return time and the ball landing point time, including:

[0035] S41, determining the ball landing point time T3 by the second sound detection device:

[0036] S42, calculating the second movement time of the table tennis ball according to the return time and the ball landing point time, as shown in formula (12),

[0037] T4=T2-T3 (12)

[0038] Among them, T4 represents the second movement time of the table tennis ball, and T3 represents the ball landing point time obtained by the second sound detection device.

[0039] Furthermore, S5 obtains the coordinates of the hitting point and landing point of the table tennis ball, including:

[0040] S51. Obtain the coordinates of the hitting point of the table tennis ball:

[0041] S511: Construct a rectangular coordinate system with the third sound detection device as the origin, the wide side of the table tennis table as the x-axis, and the long side as the y-axis. Take x as the base, and the distances between the origin and the first sound detection device and the hitting point as adjacent sides to form a triangle. Let the three points of the triangle be A, B, and C, the coordinates of the origin A be (0, 0), the coordinates of point B be (x1, 0), where x1 = c, the coordinates of point C are the coordinates of the hitting point, and let (x 击 ,y 击 );

[0042] S512: Based on the coordinates of the hitting point and the Pythagorean theorem of a triangle, a set of formulas for solving the two adjacent sides of the triangle is constructed, as shown in formula (13).

[0043]

[0044] in, Indicates the distance between the third sound detection device and the hitting point; Indicates the distance between the first sound detection device and the hitting point;

[0045] Simplify formula (13) and solve it to get the coordinates of the hitting point

[0046] S52. Obtain the coordinates of the landing point of the table tennis ball:

[0047] S521: Connect the origin, the first sound detection device, and the ball landing point to form a triangle, and use the triangle midline principle to determine the distance between the ball landing point and the origin and the first sound detection device. Obtain the coordinates of the ball landing point based on the distance between the ball landing point and the origin and the first sound detection device:

[0048] S522: Obtaining the ball landing point time T detected by the first sound detection device a1 , the ball landing point time T3 detected by the second sound detection device and the ball landing point time T b1 , using T a1 Replace T in formula (7)-formula (9) a , use T3 to replace T2 in formula (8)-formula (9), and use T b1 Replace T in formula (7) and formula (9) b , get k1, p1 and q1; use p1 and q1 to replace p and q in formula (6) to get the distance L between the landing point and the second sound detection device 落 , k1, p1, q1 and L 落 Substituting into formulas (3)-(5), we can get the distance between the ball landing point and the first sound detection device and the third sound detection device: and

[0049] S523: Assume the coordinates of the ball landing point are (x 落 ,y 落 ), according to the coordinates of the falling point and the Pythagorean theorem of triangles, a set of formulas for solving the two adjacent sides of the triangle is constructed, as shown in formula (14).

[0050]

[0051] Simplify formula (14) and solve it to get the coordinates of the falling point

[0052] Furthermore, S5 determines the running distance of the table tennis ball after the return according to the coordinates of the hitting point and the landing point of the table tennis ball, calculates the running speed of the table tennis ball after the return and the second sound wave time according to the running distance after the return and the second movement time of the table tennis ball; and obtains the actual running time of the table tennis ball after the return according to the second movement time and the second sound wave time, including:

[0053] S53, obtaining the distance between the hitting point and the landing point according to the coordinates of the hitting point and the landing point, as shown in formula (15),

[0054] L d1 =sqrt((x 击 -x 落 ) 2+(y 击 -y 落 ) 2 ) (15)

[0055] S54, calculating the running speed of the table tennis ball after the return and the second sound wave time according to the return running distance and the second movement time of the table tennis ball, as shown in formulas (16) and (17),

[0056] v=L d1 / T4 (16)

[0057] T s1 =L d1 / V s (17)

[0058] S55. Obtain the actual running time of the table tennis ball after hitting back according to the second movement time and the second sound wave time of the table tennis ball, as shown in formula (18):

[0059] Tp2=T4-T s1 (18).

[0060] Furthermore, S6 obtains the time interval of the ball machine serving the ball according to the actual running time before the table tennis ball is hit back and the actual running time after the table tennis ball is hit back, and determines the serving speed of the ball machine according to the running speed after the table tennis ball is hit back, including:

[0061] S61. Obtain the time interval T of the ball machine serving according to the actual running time before the table tennis ball is hit back and the actual running time after the table tennis ball is hit back, as shown in formula (19):

[0062] T=Tp1+Tp2 (19)

[0063] Wherein, Tp1 represents the actual running time before the ping-pong ball is hit back, and Tp2 represents the actual running time after the ping-pong ball is hit back;

[0064] S62. Determine the serving speed of the ball serving machine according to the running speed v of the table tennis ball after the return, so that the serving speed of the ball serving machine is equal to the running speed of the table tennis ball after the return.

[0065] Beneficial effects: The present invention determines the hitting time and landing time of the table tennis ball and obtains the round-trip time. It can adjust the serving interval of the ball serving machine in real time to be consistent with the round-trip time according to the round-trip time of the table tennis ball during training of different users. At the same time, it obtains the return speed of the table tennis ball and adjusts the serving speed of the ball serving machine in real time to be consistent with the return speed, ensuring uninterrupted movement between balls. It can also be adjusted in real time according to the level of different users to achieve the maximum training effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0067] Figure 1 A method flow chart of an adaptive serving control method for a table tennis serving machine provided by the present invention;

[0068] Figure 2 Schematic diagram of the whole detection device according to an embodiment of the present invention;

[0069] Figure 3 A schematic diagram of a hitting point according to an embodiment of the present invention;

[0070] Figure 4 This is a schematic diagram of hitting distance according to an embodiment of the present invention;

[0071] Figure 5 A schematic diagram of a hitting point position according to an embodiment of the present invention;

[0072] Figure 6 A schematic diagram of another hitting point position according to an embodiment of the present invention;

[0073] Figure 7 A schematic diagram of a ball return circuit according to an embodiment of the present invention;

[0074] Figure 8 A schematic diagram of a ball landing point according to an embodiment of the present invention;

[0075] Figure 9 This is a schematic diagram of the distance between ball landing points according to an embodiment of the present invention;

[0076] In the figure, 1. First acoustic wave sensor; 2. Second acoustic wave sensor; 3. Third acoustic wave sensor; 4. Photoelectric sensor; 5. Ball serving machine. DETAILED DESCRIPTION

[0077] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0078] This embodiment provides a table tennis serving machine adaptive serving control method, such as Figure 1 As shown, including:

[0079] S1: obtaining the serving time of the table tennis ball through the time detection device and obtaining the returning time of the table tennis ball through the second sound detection device;

[0080] S2: Calculating the distance the table tennis ball travels before the return, and obtaining a first motion time and a first sound wave time of the table tennis ball based on the distance before the return, wherein the first motion time is used to represent the time it takes for the table tennis ball to move from the serving point to the hitting point before the return, and the first sound wave time is used to represent the time it takes for sound to propagate between the serving point and the hitting point of the table tennis ball;

[0081] S3: obtaining the actual running time of the table tennis ball before hitting back according to the first movement time of the table tennis ball and the first sound wave time;

[0082] S4: Determine the ball landing point time by a third sound detection device, and calculate a second movement time of the table tennis ball based on the return time and the ball landing point time; the second movement time is used to represent the time it takes for the table tennis ball to move from the hitting point to the landing point;

[0083] S5: Obtaining the coordinates of the hitting point and the landing point of the table tennis ball, determining the distance traveled by the table tennis ball after the return according to the hitting point and the landing point coordinates, calculating the running speed of the table tennis ball after the return according to the running distance after the return and the second movement time of the table tennis ball; obtaining the actual running time of the table tennis ball after the return according to the second movement time and the second sound wave time; the second sound wave time is used to represent the time it takes for sound to propagate between the hitting point and the landing point of the table tennis ball;

[0084] S6: obtaining a time interval for the ball machine to serve based on the actual running time before the table tennis ball is hit back and the actual running time after the table tennis ball is hit back, and determining a serving speed of the ball machine based on the running speed of the table tennis ball after the table tennis ball is hit back;

[0085] S7: adjusting the serving mode of the ball serving machine in real time according to the time interval of serving and the serving speed of the ball serving machine, so as to realize adaptive serving control of the ball serving machine.

[0086] Specifically, first, the serving time of the table tennis ball is obtained by the time detection device, and the return time of the table tennis ball is obtained by the second sound detection device, so that the running time of the table tennis ball can be accurately obtained, which prepares for obtaining the running distance according to the running time below; secondly, the running distance of the table tennis ball before the return is calculated, and the first movement time and the first sound wave time of the table tennis ball are obtained according to the running distance before the return, firstly the time difference of the table tennis ball is obtained, and the distance difference of the table tennis ball is obtained according to the time difference, and the distance difference is used to represent the distance of the table tennis ball from the serving machine to the hitting point according to the median theorem of the triangle, which can prepare for the subsequent solution of the hitting time of the table tennis ball; according to the first movement time of the table tennis ball The actual running time of the table tennis ball before the return is obtained by using the time and the first sound wave time to reduce the influence of the sound propagation time. The running time of the table tennis ball in subsequent training is adjusted according to the actual running time before the table tennis ball returns to better meet the training requirements; the landing point time is determined by the third sound detection device, and the second movement time of the table tennis ball is calculated according to the return time and the landing point time, and the running time of the table tennis ball return is calculated to prepare for the subsequent adjustment of the time interval of the table tennis ball serve according to the running time; the coordinates of the hitting point and the landing point of the table tennis ball are obtained, and the running distance of the table tennis ball after the return is determined according to the coordinates of the hitting point and the landing point of the table tennis ball. The second movement time of the table tennis ball is used to calculate the running speed of the table tennis ball after the return; the actual running time of the table tennis ball after the return is obtained according to the second movement time of the table tennis ball and the second sound wave time, and the user's ball return speed during training can be obtained according to the running speed of the table tennis ball after the return, and the serving speed of the table tennis ball serving machine can be adjusted according to the running speed to achieve the best training effect; the actual running time of the table tennis ball after the return is obtained according to the running time of the table tennis ball after the return and the time of the sound propagation running distance after the return; the time interval of the serving machine is obtained according to the actual running time before the table tennis ball returns and the actual running time after the table tennis ball returns, and the time interval of the serving machine is obtained according to the running time after the table tennis ball returns. The running speed determines the serving speed of the ball machine; finally, the serving mode of the ball machine is adjusted in real time according to the time interval between the serving machines and the serving speed of the ball machine, so as to realize the adaptive serving control of the ball machine, obtain the time interval T between the serving machines, make the interval of the ball machine adapt to the training level of the user, and adaptively adjust the serving interval to ensure the return state of the user without dropping the ball, thereby achieving the training effect; make the serving speed of the ball machine equal to the running speed of the table tennis ball after the return, and adjust the serving speed of the ball machine in real time according to the return speed of the user to ensure that there is no interruption between the balls, and can make real-time adjustments according to the levels of different users to achieve the maximum training effect.

[0087] In a specific embodiment, the method for obtaining the serving time of a table tennis ball by the time detection device and the returning time of the table tennis ball by the second sound detection device is as follows:

[0088] like Figure 2As shown, in this embodiment, the time detection device uses a photoelectric sensor, which is located at the center of the wide side of the table. The sound detection device uses three sound wave sensors, which are placed under the photoelectric sensor and on the left and right sides of the photoelectric sensor and at the corners of the table. The one to the right of the photoelectric sensor is the first sound detection device, i.e., the first sound wave sensor; the one under the photoelectric sensor is the second sound detection device, i.e., the second sound wave sensor; and the one to the left of the photoelectric sensor is the third sound detection device, i.e., the third sound wave sensor.

[0089] S11, obtaining the actual time T1 of the table tennis ball leaving the ball serving machine through a photoelectric sensor, and feeding it back to the ball serving machine control system;

[0090] S12: Obtain the return time T2 of the table tennis ball through the second sound detection device and feed it back to the ball machine control system.

[0091] In this solution, a photoelectric sensor is used to obtain the actual time when the table tennis ball leaves the ball machine, and an acoustic sensor is used to obtain the return time of the table tennis ball. This can accurately obtain the running time of the table tennis ball, preparing for obtaining the running distance based on the running time below.

[0092] In a specific embodiment, the solution for calculating the running distance of the table tennis ball before the return and obtaining the first movement time and the first sound wave time of the table tennis ball according to the running distance before the return is:

[0093] S21, obtaining the first movement time of the table tennis ball, as shown in formula (20),

[0094] T0 = T2 - T1 (20)

[0095] Wherein, T1 represents the actual time when the table tennis ball leaves the ball machine obtained by the time detection device, and T2 represents the return time obtained by the second sound detection device;

[0096] S22, such as Figure 3 and Figure 4 As shown in FIG, a triangle is formed with the wide side of the table tennis table as the base, the distances between the third sound detection device and the first sound detection device and the hitting point of the table tennis ball as the adjacent sides, and the second sound detection device and the time detection device as the midpoints. The midline theorem of the triangle is used to determine the running distance of the table tennis ball before it is hit back, as shown in formula (21).

[0097]

[0098] in, represents the distance between the first sound detection device and the hitting point, Indicates the distance between the third sound detection device and the hitting point. represents the distance the ping-pong ball travels before being hit back, and c represents the wide side of the ping-pong table;

[0099] The distances between the first sound detection device and the third sound detection device and the hitting point of the table tennis ball are used to construct the relationship between the three sides of the triangle, as shown in formulas (22), (23) and (24).

[0100]

[0101] Substituting formulas (22), (23) and (24) into formula (21), we obtain formula (25):

[0102]

[0103] Wherein, k represents the distance difference between the distance between the first sound detection device and the hitting point and the distance between the third sound detection device and the hitting point, p represents the distance difference between the distance between the first sound detection device and the hitting point and the distance the table tennis ball travels before the return, and q represents the distance difference between the distance between the third sound detection device and the hitting point and the distance the table tennis ball travels before the return. k, p, q are as shown in formulas (26), (27), and (28).

[0104] k=(T a -T b )*V s (26)

[0105] p=(T a -T2)*V s (27)

[0106] q=(T b -T2)*V s (28)

[0107] Among them, T a represents the return strike time obtained by the first sound detection device, T b V represents the return strike time obtained by the third sound detection device; s represents the speed of sound;

[0108] S23. Obtain the time for the sound to propagate the running distance according to the running distance, as shown in formula (29):

[0109]

[0110] Among them, T s Indicates the time it takes for sound to travel a distance.

[0111] In this scheme, the position of the hitting point of the table tennis ball is obtained by cameras installed around the training table, and the hitting point position is fed back to the ball serving machine control system. However, the camera cannot directly reflect the distance between the hitting point position and the ball serving machine. Therefore, the ball serving machine control system needs to obtain the time difference of the table tennis ball, and then obtain the distance difference of the table tennis ball based on the time difference. According to the median theorem of the triangle, the distance difference is used to represent the distance of the table tennis ball from the ball serving machine to the hitting point, and then the distance from the ball serving machine to the hitting point is calculated, preparing for the subsequent solution of the table tennis ball hitting time.

[0112] In a specific embodiment, the method for obtaining the actual running time before the table tennis ball is hit back according to the first movement time of the table tennis ball and the first sound wave time is:

[0113] Get the actual running time before the table tennis ball is hit back, as shown in formula (30),

[0114] Tp1=T0-T s (30).

[0115] In this solution, obtaining the actual running time of the table tennis ball before it is hit back can reduce the impact of the sound propagation time. Adjusting the running time of the table tennis ball in subsequent training according to the actual running time of the table tennis ball before it is hit back can better meet the training requirements.

[0116] In a specific embodiment, the solution for determining the ball landing point time by the third sound detection device and calculating the second movement time of the table tennis ball according to the return time and the ball landing point time is:

[0117] S41, determining the ball landing point time T3 by the second sound detection device:

[0118] S42, calculating the second movement time of the table tennis ball according to the return time and the ball landing point time, as shown in formula (31),

[0119] T4=T2-T3 (31)

[0120] Among them, T4 represents the second movement time of the table tennis ball, and T3 represents the ball landing point time obtained by the second sound detection device.

[0121] In this solution, the second movement time of the table tennis ball, that is, the time it takes for the table tennis ball to move from the hitting point to the landing point, is calculated to prepare for adjusting the time interval of the table tennis ball serving according to this time.

[0122] In a specific embodiment, the coordinates of the hitting point and the landing point of the table tennis ball are obtained, the distance traveled by the table tennis ball after the return is determined based on the hitting point and the landing point coordinates, and the speed and second sound wave time of the table tennis ball after the return are calculated based on the running distance after the return and the second movement time of the table tennis ball. The scheme for obtaining the actual running time of the table tennis ball after the return based on the second movement time and the second sound wave time is:

[0123] S51. Obtain the coordinates of the hitting point of the table tennis ball:

[0124] S511: Construct a rectangular coordinate system with the third sound detection device as the origin, the wide side of the table tennis table as the x-axis, and the long side as the y-axis. Take x as the base, and the distances between the origin and the first sound detection device and the hitting point as adjacent sides to form a triangle. Let the three points of the triangle be A, B, and C, the coordinates of the origin A be (0, 0), the coordinates of point B be (x1, 0), where x1 = c, the coordinates of point C are the coordinates of the hitting point, and let (x 击 ,y 击 ),like Figure 5 and Figure 6 As shown;

[0125] S512: Based on the coordinates of the hitting point and the Pythagorean theorem of a triangle, a set of formulas for solving the two adjacent sides of the triangle is constructed, as shown in formula (32).

[0126]

[0127] in, Indicates the distance between the third sound detection device and the hitting point; Indicates the distance between the first sound detection device and the hitting point;

[0128] Expand and simplify the second equation in formula (32) to obtain formula (33),

[0129]

[0130] Substituting the first equation in formula (32) into formula (33), we get formula (34),

[0131]

[0132] Solve to get the coordinates of the hitting point;

[0133] Figure 5 is the position when the hitting point falls in the first quadrant, Figure 6 is the position of the hitting point when it falls in the second quadrant, so formula (32) is simplified and solved to obtain the coordinates of the two hitting points, the coordinates of the first quadrant The coordinates of the second quadrant are

[0134] S52. Obtain the coordinates of the landing point of the table tennis ball:

[0135] S521: The location of the table tennis ball landing point and the return line Figure 7 and Figure 8 As shown, the origin, the first sound detection device and the ball landing point are connected to form a triangle, and the distance between the ball landing point and the origin and the first sound detection device is determined using the triangle midline principle, as shown in FIG. Figure 9 As shown, the coordinates of the ball landing point are obtained according to the distance between the ball landing point and the origin and the first sound detection device:

[0136] S522: Obtaining the ball landing point time T detected by the first sound detection device a1 , the ball landing point time T3 detected by the second sound detection device and the ball landing point time T b1 , using T a1 Replace T in formula (26)-formula (28) a , use T3 to replace T2 in formula (27)-formula (28), and use T b1 Replace T in formula (26) and formula (28) b , get k1, p1 and q1; use p1 and q1 to replace p and q in formula (25) to get the distance L between the landing point and the second sound detection device 落 , k1, p1, q1 and L 落 Substituting into formulas (22)-(24), we can get the distance between the ball landing point and the first sound detection device and the third sound detection device: and

[0137] S523: Assume the coordinates of the ball landing point are (x 落 ,y 落 ), according to the coordinates of the falling point and the Pythagorean theorem of triangles, a set of formulas for solving the two adjacent sides of the triangle is constructed, as shown in formula (35).

[0138]

[0139] Simplify formula (35) and solve it to get the coordinates of the falling point

[0140] S53, obtaining the distance between the hitting point and the landing point according to the coordinates of the hitting point and the landing point, as shown in formula (36),

[0141] L d1 =sqrt((x 击 -x 落 ) 2+(y 击 -y 落 ) 2 ) (36)

[0142] S54, calculating the running speed of the table tennis ball after the return and the time it takes for the sound to propagate the return running distance according to the return running distance and the running time of the table tennis ball, as shown in formulas (37) and (38),

[0143] v=L d1 / T4 (37)

[0144] T s1 =L d1 / V s (38)

[0145] S55. According to the running time of the table tennis return and the time of the sound propagation running distance of the return, the actual running time of the table tennis return is obtained, as shown in formula (39):

[0146] Tp2=T4-T s1 (39).

[0147] In this solution, the control system of the ball serving machine determines the accurate coordinates of the hitting point of the table tennis ball according to the distance between the hitting point of the table tennis ball and the ball serving machine, and determines the accurate coordinates of the landing point of the table tennis ball according to the distance between the landing point of the table tennis ball and the serving point. After determining the distance between the hitting point and the landing point of the table tennis ball through the coordinates of the landing point, the running speed of the table tennis ball after the return and the actual running time of the table tennis ball return are obtained. The running speed of the table tennis ball after the return can be used to obtain the return speed of the user during training, and the serving speed of the table tennis ball serving machine can be adjusted according to the running speed to achieve the best training effect. The actual running time of the table tennis ball return can be obtained, which can prepare for the subsequent adjustment of the serving interval according to the running time.

[0148] In a specific embodiment, the time interval of the ball machine's serving is obtained based on the actual running time before the table tennis ball is hit back and the actual running time after the table tennis ball is hit back, and the solution for determining the serving speed of the ball machine based on the running speed of the table tennis ball after the table tennis ball is hit back is:

[0149] S61. Obtain the time interval T of the ball machine serving according to the actual running time before the table tennis ball is hit back and the actual running time after the table tennis ball is hit back, as shown in formula (40).

[0150] T=Tp1+Tp2 (40)

[0151] Wherein, Tp1 represents the actual running time before the ping-pong ball is hit back, and Tp2 represents the actual running time after the ping-pong ball is hit back;

[0152] S62. Determine the serving speed of the ball serving machine according to the running speed v of the table tennis ball after the return, so that the serving speed of the ball serving machine is equal to the running speed of the table tennis ball after the return.

[0153] In this solution, the ball machine control system can obtain the time interval T between the ball machine's serving according to the actual running time before and after the table tennis ball is returned, so that the interval of the ball machine can adapt to the user's training level, and adaptively adjust the serving interval to ensure the user's ball return state without dropping the ball, thereby achieving a training effect; the serving speed of the ball machine is made equal to the running speed of the table tennis ball after the return, and the serving speed of the ball machine is adjusted in real time according to the user's return speed to ensure uninterrupted ball delivery, and can be adjusted in real time according to the level of different users to achieve the maximum training effect.

[0154] In a specific embodiment, the serving mode of the ball serving machine is adjusted in real time according to the time interval and the serving speed of the ball serving machine, and the solution for realizing the adaptive serving control of the ball serving machine is:

[0155] In this embodiment, the ball serving machine control system adjusts the speed of the ball serving machine to be equal to the running speed after the return according to the data obtained in the previous calculation, and at the same time ensures that the running time of the ball serving machine after the serve is equal to the running time after the table tennis ball is returned, that is, Tp1=Tp2. The serving interval of the ball serving machine is adjusted to be twice the running time after the return. The program of the ball serving machine is set to realize the adaptive serving control of the ball serving machine to match the training requirements of different users and achieve the best training effect.

[0156] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A table tennis serving machine adaptive serving control method, characterized in that: include: S1: obtaining the serving time of the table tennis ball through the time detection device and obtaining the returning time of the table tennis ball through the second sound detection device; S2: Calculating the distance the table tennis ball travels before the return, and obtaining a first motion time and a first sound wave time of the table tennis ball based on the distance before the return, wherein the first motion time is used to represent the time it takes for the table tennis ball to move from the serving point to the hitting point before the return, and the first sound wave time is used to represent the time it takes for sound to propagate between the serving point and the hitting point of the table tennis ball; S3: obtaining the actual running time of the table tennis ball before hitting back according to the first movement time of the table tennis ball and the first sound wave time; S4: Determine the ball landing point time by a third sound detection device, and calculate a second movement time of the table tennis ball based on the return time and the ball landing point time; the second movement time is used to represent the time it takes for the table tennis ball to move from the hitting point to the landing point; S5: Obtaining the coordinates of the hitting point and the landing point of the table tennis ball, determining the running distance of the table tennis ball after the return according to the hitting point and the landing point coordinates, calculating the running speed of the table tennis ball after the return and the second sound wave time according to the running distance after the return and the second movement time of the table tennis ball; obtaining the actual running time of the table tennis ball after the return according to the second movement time and the second sound wave time; The second sound wave time is used to represent the time it takes for the sound to propagate between the point where the table tennis ball hits and the point where the ball lands; S6: obtaining a time interval for the ball machine to serve based on the actual running time before the table tennis ball is hit back and the actual running time after the table tennis ball is hit back, and determining a serving speed of the ball machine based on the running speed of the table tennis ball after the table tennis ball is hit back; S7: adjusting the serving mode of the ball serving machine in real time according to the time interval of serving and the serving speed of the ball serving machine, so as to realize adaptive serving control of the ball serving machine.

2. The adaptive serving control method of a table tennis serving machine according to claim 1, characterized in that: S2 calculates the running distance of the table tennis ball before the return, and obtains the first movement time and the first sound wave time of the table tennis ball according to the running distance before the return, including: S21, obtaining the first movement time of the table tennis ball, as shown in formula (1), T0 = T2 - T1 (1) where T1 represents the actual time when the table tennis ball leaves the ball machine obtained by the time detection device, and T2 represents the return time obtained by the second sound detection device; S22. A triangle is formed with the wide side of the table tennis table as the base, the distances between the third sound detection device and the first sound detection device and the hitting point of the table tennis ball as adjacent sides, and the second sound detection device and the time detection device as the midpoints. The midline theorem of the triangle is used to determine the distance the table tennis ball travels before hitting back, as shown in formula (2). in, represents the distance between the first sound detection device and the hitting point, Indicates the distance between the third sound detection device and the hitting point. represents the distance the ping-pong ball travels before being hit back, and c represents the wide side of the ping-pong table; The relationship between the three sides of the triangle is constructed using the distances between the first sound detection device and the third sound detection device and the hitting point of the table tennis ball, as shown in formulas (3), (4) and (5). Substituting formulas (3), (4) and (5) into formula (2), we get formula (6): Wherein, k represents the distance difference between the distance between the first sound detection device and the hitting point and the distance between the third sound detection device and the hitting point, p represents the distance difference between the distance between the first sound detection device and the hitting point and the distance the table tennis ball travels before the return, and q represents the distance difference between the distance between the third sound detection device and the hitting point and the distance the table tennis ball travels before the return. k, p, q are shown in formulas (7), (8), and (9). k=(T a -T b )*V s (7) p=(T a -T2)*V s (8) q=(T b -T2)*V s (9) Among them, T a represents the return strike time obtained by the first sound detection device, T b V represents the return strike time obtained by the third sound detection device; s represents the speed of sound; S23. Obtain the time for the sound to propagate the running distance according to the running distance, as shown in formula (10): Among them, T s Indicates the time it takes for sound to travel a distance.

3. The adaptive serving control method of a table tennis serving machine according to claim 2, characterized in that: S3 obtains the actual running time before the table tennis ball is hit back according to the first movement time of the table tennis ball and the first sound wave time, including: Get the actual running time before the table tennis ball is hit back, as shown in formula (11), Tp1=T0-T s (11)。 4. The adaptive serving control method of a table tennis serving machine according to claim 2, characterized in that: S4 determines the ball landing point time by a third sound detection device, and calculates the second movement time of the table tennis ball according to the return time and the ball landing point time, including: S41, determining the ball landing point time T3 by the second sound detection device: S42, calculating the second movement time of the table tennis ball according to the return time and the ball landing point time, as shown in formula (12), T4=T2-T3 (12) Wherein, T4 represents the second movement time of the table tennis ball, and T3 represents the ball landing point time obtained by the second sound detection device.

5. The adaptive serving control method of a table tennis serving machine according to claim 4, characterized in that: S5 obtains the coordinates of the hitting point and landing point of the table tennis ball, including: S51. Obtain the coordinates of the hitting point of the table tennis ball: S511: Construct a rectangular coordinate system with the third sound detection device as the origin, the wide side of the table tennis table as the x-axis, and the long side as the y-axis. Take x as the base, and the distances between the origin and the first sound detection device and the hitting point as adjacent sides to form a triangle. Let the three points of the triangle be A, B, and C, the coordinates of the origin A be (0,0), the coordinates of point B be (x1,0), where x1=c, the coordinates of point C are the coordinates of the hitting point, and let (x 击 ,y 击 ); S512: Based on the coordinates of the hitting point and the Pythagorean theorem of a triangle, a set of formulas for solving the two adjacent sides of the triangle is constructed, as shown in formula (13). in, Indicates the distance between the third sound detection device and the hitting point; Indicates the distance between the first sound detection device and the hitting point; Simplify formula (13) and solve it to get the coordinates of the hitting point S52. Obtain the coordinates of the landing point of the table tennis ball: S521: Connect the origin, the first sound detection device, and the ball landing point to form a triangle, and use the triangle midline principle to determine the distance between the ball landing point and the origin and the first sound detection device. Obtain the coordinates of the ball landing point based on the distance between the ball landing point and the origin and the first sound detection device: S522: Obtaining the ball landing point time T detected by the first sound detection device a1 , the ball landing point time T3 detected by the second sound detection device and the ball landing point time T b1 , using T a1 Replace T in formula (7)-formula (9) a , use T3 to replace T2 in formula (8)-formula (9), and use T b1 Replace T in formula (7) and formula (9) b , get k1, p1 and q1; use p1 and q1 to replace p and q in formula (6) to get the distance L between the landing point and the second sound detection device 落 , k1, p1, q1 and L 落 Substituting into formulas (3)-(5), we can get the distance between the ball landing point and the first sound detection device and the third sound detection device: and S523: Assume the coordinates of the ball landing point are (x 落 ,y 落 ), according to the coordinates of the falling point and the Pythagorean theorem of triangles, a set of formulas for solving the two adjacent sides of the triangle is constructed, as shown in formula (14). Simplify formula (14) and solve it to get the coordinates of the falling point 6. The adaptive serving control method of a table tennis serving machine according to claim 5, characterized in that: S5 determines the running distance of the table tennis ball after the return according to the coordinates of the hitting point and the landing point of the table tennis ball, and calculates the running speed and the second sound wave time of the table tennis ball after the return according to the running distance and the second motion time of the table tennis ball; The actual running time after the table tennis ball is hit back is obtained according to the second movement time and the second sound wave time of the table tennis ball, including: S53, obtaining the distance between the hitting point and the landing point according to the coordinates of the hitting point and the landing point, as shown in formula (15), L d1 =sqrt((x 击 -x 落 ) 2 +(y 击 -y 落 ) 2 ) (15) S54, calculating the running speed of the table tennis ball after the return and the second sound wave time according to the return running distance and the second movement time of the table tennis ball, as shown in formulas (16) and (17), v=L d1 / T4 (16) T s1 =L d1 / V s (17) S55. Obtain the actual running time of the table tennis ball after hitting back according to the second movement time and the second sound wave time of the table tennis ball, as shown in formula (18): Tp2=T4-T s1 (18)。 7. The adaptive serving control method of a table tennis serving machine according to claim 6, characterized in that: S6 obtains the time interval of the ball machine serving the ball according to the actual running time before the table tennis ball is hit back and the actual running time after the table tennis ball is hit back, and determines the serving speed of the ball machine according to the running speed of the table tennis ball after the table tennis ball is hit back, including: S61. Obtain the time interval T of the ball machine serving according to the actual running time before the table tennis ball is hit back and the actual running time after the table tennis ball is hit back, as shown in formula (19): T=Tp1+Tp2 (19) Wherein, Tp1 represents the actual running time before the ping-pong ball is hit back, and Tp2 represents the actual running time after the ping-pong ball is hit back; S62. Determine the serving speed of the ball serving machine according to the running speed v of the table tennis ball after the return, so that the serving speed of the ball serving machine is equal to the running speed of the table tennis ball after the return.

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