Sensing device for ball hitting detection and tennis racket

Abstract

The invention discloses a sensing device for ball hitting detection and a tennis racket. The sensing device comprises a sensor element, and the sensor element is combined with a data fusion algorithm to conduct data monitoring on the ball hitting force, the ball hitting speed and the ball hitting position of the tennis racket; the sensor element comprises an IMU (Inertial Measurement Unit) sensor, physical quantity parameters in a tennis racket batting and waving process and an acoustic sensor, and is used for analyzing batting force, batting speed and batting position; the Bluetooth communication element is used for realizing wireless communication; the energy collector is used for converting kinetic energy generated by ball hitting of the tennis racket into electric energy to supply power to the sensor component; data monitoring is carried out on the ball hitting force, the ball hitting speed and the ball hitting position, the IMU sensor, the acoustic sensor and the energy collector are used in cooperation and combined with a data fusion algorithm, the defects of a traditional single sensor are effectively overcome, the positioning and tracking precision is improved, the energy collector is used for storing and using electric energy, and the positioning and tracking precision is improved. And power consumption is reduced.

Description

Technical Field

[0001] The present invention relates to a sensing device, and more particularly to a sensing device for detecting a hit and a tennis racket. Background Art

[0002] Currently, most existing sensors use camera tracking. However, it may be limited by the camera resolution, viewing angle, and the accuracy of the image recognition algorithm, resulting in inaccurate tracking of the tennis flight trajectory, and problems such as trajectory breakpoints and position deviations are likely to occur. When using radar tracking, there may also be problems such as limited detection range and inaccurate positioning of balls at close range. Summary of the Invention

[0003] In order to solve the deficiencies of the above technologies, the present invention provides a sensing device for detecting a hit.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is: a sensing device for detecting a hit, including a sensor element, and the sensor element is used to combine a data fusion algorithm to monitor data on the hitting force, hitting speed, and hitting position of the tennis racket.

[0005] The sensor element includes,

[0006] An IMU sensor, which collects physical quantity parameters of the sensor element during the swinging process of the tennis racket hitting the ball;

[0007] An acoustic sensor, which captures the sound signal when the tennis racket hits the ball to analyze the hitting force, hitting speed, and hitting position;

[0008] A Bluetooth communication element, which realizes wireless communication between the tennis racket and the user's mobile phone;

[0009] It further includes,

[0010] An energy collector, which is used to convert the kinetic energy generated by the tennis racket hitting the ball into electrical energy to supply power to the sensor element.

[0011] Furthermore, an IMU sensor circuit, an acoustic sensor circuit, an energy collector circuit, a main control circuit, and a Bluetooth transmission circuit are formed. The signal output ends of the IMU sensor circuit, the acoustic sensor circuit, and the energy collector circuit are respectively connected to the signal input end of the main control circuit, and the signal input end of the Bluetooth transmission circuit is connected to the signal output end of the main control circuit.

[0012] Furthermore, the IMU sensor and the acoustic sensor are jointly installed at the throat position of the tennis racket;

[0013] The IMU sensor monitors the coordinates of the tennis racket during the swing and the coordinates at the time of hitting, and then obtains the acceleration and the hitting angle;

[0014] The acoustic sensor includes a plurality of closely arranged microphones.

[0015] Furthermore, the acoustic sensor analyzes the phase differences of the same sound wave transmitted through a plurality of microphones in an array, and obtains the sound source direction based on the phase differences. The phase differences include the time differences of the sound signals obtained by two adjacent microphones to calculate the hitting position.

[0016] Furthermore, the formula for the phase difference is:

[0017] X = v(t1 - t2),

[0018] where X is the phase difference, i.e., the displacement; v is the propagation speed of the sound signal; and t1 - t2 is the time difference of the sound signal.

[0019] Furthermore, the acoustic sensor analyzes the magnitude of the force exerted by the player when hitting the ball by capturing the amplitude at the moment of hitting the ball;

[0020] The acoustic sensor calculates the racket head speed when the tennis racket hits the ball and the flying speed of the tennis ball after being hit using the Doppler effect according to the change in the sound frequency it collects.

[0021] Furthermore, the energy collector collects the electric energy converted by the piezoelectric effect when the tennis racket hits the ball;

[0022] The energy collector collects the electric energy generated by the electromagnetic induction device when the tennis ball passes through the tennis racket;

[0023] The energy collector collects the electric energy generated when the tennis ball contacts and rubs against the tennis racket.

[0024] Furthermore, it can also monitor the usage status of the tennis racket and evaluate the hitting effect;

[0025] The usage status monitoring includes racket damage warning and string tension detection. Among them,

[0026] For the racket damage warning, the acoustic sensor monitors the abnormal change in the hitting sound of the tennis racket and issues a warning;

[0027] For the string tension detection, the acoustic sensor monitors the frequency and amplitude including the hitting sound information to analyze the tension of the strings of the tennis racket;

[0028] The hitting effect evaluation includes sweet spot hitting statistics, hitting rotation detection, and racket face stability analysis.

[0029] A tennis racket includes at least one sensing device for hitting detection as described in any one of the above.

[0030] Furthermore, it is made of piezoelectric material and is equipped with a battery or a supercapacitor inside the tennis racket, and an electromagnetic reaction device is also equipped inside the tennis racket.

[0031] A sensing device for hitting detection monitors data on hitting force, hitting speed, and hitting position. By using an IMU sensor, an acoustic sensor, and an energy collector in combination and integrating a data fusion algorithm, it effectively makes up for the defects of traditional single sensors, improves the accuracy of positioning and tracking, and utilizes the function of the energy collector to store and use electrical energy, thereby reducing power consumption and achieving the effect of low power consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of the communication process of the present invention.

[0033] Figure 2 It is the circuit schematic of the present invention Figure 1 .

[0034] Figure 3 It is the circuit schematic of the present invention Figure 2 .

[0035] Figure 4 It is a schematic diagram of the installation of the IMU sensor in Example 5.

[0036] Figure 5 It is a schematic diagram of the installation of the acoustic sensor in Example 5.

[0037] Figure 6 It is the analysis of the sound data during hitting in Example 5.

[0038] Figure 7 It is the data analysis of the IMU sensor in Example 5. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0039] The present invention will be further described in detail below in conjunction with the drawings and specific embodiments.

[0040] Example 1

[0041] As Figures 1-3 collectively shown, this embodiment relates to a sensing device for hitting detection, including sensor elements. The sensor elements are used to combine a data fusion algorithm to monitor data on the hitting force, hitting speed, and hitting position of a tennis racket. It should be noted that the specific content of the data fusion algorithm is not the part to be protected by this application, so the algorithm itself will not be introduced;

[0042] In this embodiment, the sensor elements include:

[0043] An IMU sensor, which collects physical quantity parameters of the sensor element during the swinging process of the tennis racket when hitting the ball; an acoustic sensor, which captures the sound signal when the tennis racket hits the ball to analyze the hitting force, hitting speed and hitting position; a Bluetooth communication element, which realizes wireless communication between the tennis racket and the user's mobile phone; it should be noted that the IMU sensor, acoustic sensor, and Bluetooth communication element are all existing technologies and not the inventions of this application;

[0044] It further includes: an energy collector, which is used to convert the kinetic energy generated by the tennis racket hitting the ball into electric energy to supply power to the sensor components.

[0045] The low-power sensor in this embodiment consists of an IMU sensor circuit, an acoustic sensor circuit, an energy collector circuit, a main control circuit, and a Bluetooth transmission circuit. The signal output ends of the IMU sensor circuit, acoustic sensor circuit, and energy collector circuit are respectively connected to the signal input end of the main control circuit, and the signal input end of the Bluetooth transmission circuit is connected to the signal output end of the main control circuit, thereby forming signal communication.

[0046] During actual assembly, the IMU sensor and the acoustic sensor are jointly installed at the throat position of the tennis racket.

[0047] On this basis, the IMU sensor monitors the coordinates when the tennis racket swings and the coordinates when hitting the ball, and then obtains the acceleration and hitting angle. It should be noted that the IMU sensor is an inertial sensor, which includes an accelerometer and a gyroscope. In this embodiment, the accelerometer integrated in the IMU sensor is used to measure the acceleration when the tennis racket swings, and the gyroscope integrated in the IMU sensor is also used to measure the angular velocity when the tennis racket swings; the acoustic sensor includes a plurality of closely arranged microphones.

[0048] Regarding the acoustic sensor, it analyzes the phase difference of the same sound wave transmission through the array of its multiple microphones, and obtains the sound source direction based on the phase difference. The phase difference includes the time difference of the sound signals obtained by two adjacent microphones to calculate the hitting position.

[0049] Further, the formula for the phase difference is:

[0050] X = v(t1 - t2),

[0051] where X is the phase difference, that is, displacement; v is the propagation speed of the sound signal; t1 - t2 is the time difference of the sound signal.

[0052] The acoustic sensor analyzes the magnitude of the force exerted by the player when hitting the ball by capturing the amplitude at the moment of hitting;

[0053] The acoustic sensor calculates the racket head speed when the tennis racket hits the ball and the flying speed of the tennis ball after being hit using the Doppler effect based on the change in the sound frequency it collects.

[0054] Based on this, it can be understood that this embodiment realizes the monitoring of hitting data, and the monitoring of hitting data specifically includes:

[0055] Analysis of hitting force. By capturing the sound signal generated at the moment of hitting and combining with the data fusion algorithm, the magnitude of the force exerted by the player when hitting the ball is analyzed. In practical applications, for example, during training or competitions, players can use this to understand their force application situation, and coaches can also formulate more reasonable force training plans for players based on the data;

[0056] Measurement of hitting speed. According to the information including the change in sound frequency collected by the acoustic sensor, the head speed of the tennis racket when hitting the ball and the flying speed of the tennis ball after being hit are estimated using the Doppler effect, which can help players optimize their swing actions and improve the hitting speed;

[0057] Positioning of hitting point. According to the difference in sound characteristics generated by hitting the ball with different parts of the racket, combined with the above-mentioned phase difference calculation, the specific position of the hitting point on the racket surface is determined. Players can adjust their hitting habits accordingly to improve hitting accuracy.

[0058] In this embodiment, the energy collector has the following effects:

[0059] Energy collection,

[0060] Collect the electric energy converted by the piezoelectric effect when the tennis racket hits the ball, that is, utilize the piezoelectric effect. When the tennis racket hits the ball, the impact force causes the piezoelectric material in the racket to vibrate and deform, the charge centers inside the material shift to produce polarization, and charges appear on the surface, converting the mechanical energy of hitting the ball into electric energy, and then collecting it through the energy collector; the energy collector collects the electric energy generated by the electromagnetic induction device when the tennis passes through the tennis racket, that is, utilize the principle of electromagnetic induction. When the tennis racket with magnetism hits and swings, the magnetic flux of the coil in the electromagnetic induction device of the tennis racket changes, generating an induced electromotive force and current, realizing the conversion of mechanical energy to electric energy, and then collecting it through the energy collector; the energy collector collects the electric energy generated when the tennis contacts and rubs against the tennis racket, that is, utilize the principle of triboelectrification. When the tennis contacts and rubs against the tennis racket, due to the different binding forces of materials to electrons, electrons transfer on the surfaces of both to carry opposite charges and generate static electricity, and the static electricity collection device of the energy collector can convert it into electric energy.

[0061] Energy conversion, that is, the energy collector mentioned above collects the electric energy converted by the piezoelectric effect, collects the electric energy converted by the electromagnetic induction effect, and converts the electric energy generated by triboelectrification.

[0062] Energy management. After energy conversion, the converted electric energy is rectified, filtered, and voltage-stabilized to stabilize the voltage and remove impurities. In addition, the charging and discharging of the energy collector are controlled to ensure safety and efficiency.

[0063] Energy storage and usage. The processed electric energy is stored in a battery or a supercapacitor built into the racket, and then powers the sensing device for shot detection.

[0064] Embodiment 2

[0065] Based on Embodiment 1, this embodiment further expands the functional diversity of the sensing device for shot detection in actual use.

[0066] This embodiment has the ability to monitor the device status, including:

[0067] Racket damage warning. Continuously monitor the sound changes of the tennis racket during use. When there is internal structural damage or cracks in the tennis racket, the hitting sound will be abnormal, and the acoustic sensor can issue a warning in time to remind the player to check and replace the racket in time, avoiding affecting performance due to racket damage during the game or training;

[0068] String tension detection. Analyze the tension of the strings of the tennis racket according to the frequency and amplitude characteristics of the hitting sound, and remind the player to adjust the string tension in time to ensure the stability of the racket performance.

[0069] Embodiment 3

[0070] Based on Embodiment 1, this embodiment further expands the functional diversity of the sensing device for shot detection in actual use, which is different from Embodiment 2.

[0071] This embodiment has the ability to evaluate the hitting effect, including:

[0072] Sweet spot hitting statistics. It can identify whether the player's hit hits the sweet spot of the racket face, and count the number and proportion data of sweet spot hits. The player can analyze their sweet spot hitting situation in the game or training based on these data and adjust the hitting strategy and action;

[0073] Hit rotation detection. Analyze the rotation situation of the tennis ball after being hit, such as the rotation direction and rotation speed, based on the characteristics of the hitting sound. The player can better master the hitting skills and increase the variation and aggressiveness of the hit according to the rotation data;

[0074] Racket face stability analysis. Evaluate the racket face stability at the moment of hitting by analyzing the stability and vibration characteristics of the hitting sound. The player can choose a more suitable racket for themselves or adjust the existing racket according to the feedback.

[0075] Embodiment 4

[0076] A tennis racket includes at least one sensing device for shot detection. The tennis racket is made of piezoelectric material and is equipped with a battery or a supercapacitor inside. The tennis racket is also equipped with an electromagnetic reaction device.

[0077] Example 5

[0078] Based on Examples 1 - 4, this example demonstrates the installation state of the sensing device for tennis racket assembly and hitting detection disclosed in Example 4 during actual use, and provides corresponding experiments specifically.

[0079] As Figure 4 shown, it is the installation position of the IMU sensor in this example. As Figure 5 shown, it is the installation position of the acoustic sensor in this example. The two echo and explain that the IMU sensor and the acoustic sensor described in Example 1 are jointly installed at the throat position of the tennis racket.

[0080] As Figure 6 shown, the experiment in this example shows the analysis of the sound data when the tennis racket hits the ball. By observing the positions of the left and right peaks and the vibration frequency, the hitting position can be judged. Specifically, in the experiment, when the left peak does not exceed -40 dB and the right peak exceeds -50 dB, the hitting position is in the upper-middle part of the racket; when the left peak does not exceed -40 dB and the right peak does not exceed -50 dB in the experiment, the hitting position is in the middle of the racket; when the left peak exceeds -40 dB and the right peak does not exceed -50 dB in the experiment, the hitting position is in the lower-middle part of the racket.

[0081] Based on the above experiments, it further verifies the speculation that the hitting position can be judged by the positions of the left and right peaks and the vibration frequency, and refines the speculation range. It can also draw the conclusion that the closer the hitting position is to the racket handle, the higher the vibration frequency of the sound.

[0082] As Figure 7 shown, the experiment in this example also shows the acceleration data and angular velocity data when the tennis racket hits the ball, specifically as follows:

[0083] As Figure 7 shown in the six sub - figures in it, Forehand, Backhand, and Serve marked in the six figures are the forehand action, backhand action, and serving action of the tennis racket hitting the ball respectively, and are distinguished by colors respectively. Figure 7 ax(g), ay(g), az(g) marked from left to right in the three upper - row sub - figures are the accelerations in the x, y, and z axes (unit: gravitational acceleration g) under different actions (forehand, backhand, serve). The horizontal axis of each sub - figure represents time. Therefore, the acceleration change situations of different actions in each axis can be obtained.

[0084] Figure 7The wx (deg / s), wy (deg / s), and wz (deg / s) marked from left to right in the three sub - graphs in the middle and lower rows are the angular velocities in the x, y, and z axes (in degrees per second) under different actions (forehand, backhand, serve). The horizontal axis of each sub - graph represents time. Therefore, the changes in angular velocity in each axis for different actions can be obtained.

[0085] Based on the above experimental data, it can be further clarified that:

[0086] In terms of action differentiation, the forehand and backhand actions are relatively similar in terms of changes in acceleration and angular velocity, especially on the ax and az axes; the serve action is more complex in terms of changes in acceleration and angular velocity, especially in the middle time period, showing higher dynamics.

[0087] In terms of motion characteristics, the forehand and backhand actions mainly have large changes in acceleration and angular velocity in the y - axis direction; the serve action has large changes in acceleration and angular velocity in all axis directions, indicating that its motion pattern is more complex.

[0088] In terms of time - series characteristics, the middle time period (approximately between 15 and 25) is the period with the most significant action changes, corresponding to the key stages of the action; the changes in the forehand and backhand actions in the time series are relatively stable, while the serve action shows more fluctuations and changes.

[0089] This application discloses a sensing device for hitting detection, which monitors data on hitting force, hitting speed, and hitting position. By using an IMU sensor, an acoustic sensor, and an energy harvester in combination with a data fusion algorithm, it effectively makes up for the defects of traditional single sensors, improves the accuracy of positioning and tracking, and uses the function of the energy harvester to store and use electrical energy, thereby reducing power consumption and achieving the effect of low power consumption.

[0090] The above - mentioned embodiments are not limitations on the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions, or substitutions made by those skilled in the art within the scope of the technical solution of the present invention also fall within the protection scope of the present invention.

Claims

1. A sensing device for hitting detection, characterized in that: It includes sensor elements, which are used to combine data fusion algorithms to monitor data such as the hitting force, hitting speed, and hitting position of a tennis racket; The sensor elements include, An IMU sensor that collects physical quantity parameters of the sensor elements during the swinging process of the tennis racket for hitting; An acoustic sensor that captures the sound signal when the tennis racket hits the ball to analyze the hitting force, hitting speed, and hitting position; A Bluetooth communication element that realizes wireless communication between the tennis racket and the user's mobile phone; It also includes, An energy harvester that converts the kinetic energy generated by the tennis racket hitting the ball into electrical energy to power the sensor components.

2. The sensing device for hitting detection according to claim 1, wherein: There are an IMU sensor circuit, an acoustic sensor circuit, an energy harvester circuit, a main control circuit, and a Bluetooth transmission circuit. The signal output ends of the IMU sensor circuit, the acoustic sensor circuit, and the energy harvester circuit are respectively connected to the signal input end of the main control circuit, and the signal input end of the Bluetooth transmission circuit is connected to the signal output end of the main control circuit.

3. The sensing device for hitting detection according to claim 1, wherein: The IMU sensor and the acoustic sensor are jointly installed at the throat position of the tennis racket; The IMU sensor monitors the coordinates when the tennis racket swings and the coordinates when hitting the ball, and then obtains the acceleration and hitting angle; The acoustic sensor includes a plurality of microphones arranged closely.

4. The sensing device for hitting detection according to claim 3, wherein: The acoustic sensor analyzes the phase difference of the same sound wave transmission through the alignment of the plurality of microphones, and obtains the sound source direction based on the phase difference. The phase difference includes the time difference of the sound signals obtained by two adjacent microphones to calculate the hitting position.

5. The sensing device for hitting detection according to claim 4, wherein The formula for the phase difference is: X = v(t1 - t2), where X is the phase difference, that is, the displacement; v is the propagation speed of the sound signal; t1 - t2 is the time difference of the sound signal.

6. The sensing device for hitting detection according to claim 3, wherein: The acoustic sensor analyzes the magnitude of the force exerted by the player when hitting the ball by capturing the amplitude at the moment of hitting; The acoustic sensor calculates the head speed of the tennis racket when hitting the ball and the flying speed of the tennis ball after being hit by using the Doppler effect based on the change in the sound frequency it collects.

7. The sensing device for hitting detection according to claim 1, wherein: The energy harvester collects the electrical energy converted by the piezoelectric effect when the tennis racket hits the ball; The energy harvester collects the electrical energy generated by the electromagnetic induction device when the tennis passes through the tennis racket; The energy harvester collects the electrical energy generated when the tennis and the tennis racket are in contact and friction.

8. The sensing device for hitting detection according to claim 7, characterized in that: It can also realize the monitoring of the use state of the tennis racket and the evaluation of the hitting effect; The monitoring of the use state includes racket damage warning and string tension detection. Among them, For racket damage warning, the acoustic sensor monitors abnormal changes in the hitting sound of the tennis racket and issues a warning; For string tension detection, the acoustic sensor monitors the frequency and amplitude including the hitting sound information to analyze the tension situation of the strings of the tennis racket; The evaluation of the hitting effect includes sweet spot hitting statistics, hitting rotation detection, and racket face stability analysis.

9. A tennis racket, characterized in that: It includes at least one sensing device for hitting detection according to any one of claims 1 - 8.

10. The tennis racket according to claim 9, wherein: It is made of piezoelectric material and is equipped with a battery or a supercapacitor inside the tennis racket, and an electromagnetic reaction device is also equipped inside the tennis racket.

Images