Racket tension measuring instrument and measuring method

Abstract

The invention discloses a racket tension measuring instrument and method, and the instrument comprises a first piezoelectric ceramic layer of a vibration generation part, a vibration control circuit which is electrically connected with the first piezoelectric ceramic layer, and a second piezoelectric ceramic piece of a vibration induction part, the second piezoelectric ceramic piece is electrically connected with a vibration induction circuit and a processor in sequence, and the processor is electrically connected with a display module. The first piezoelectric ceramic layer and the second piezoelectric ceramic layer are respectively sintered on the surface of the annular metal substrate, the inner ring of the annular metal substrate is connected with a counterweight connecting piece, and one end, far away from the annular metal substrate, of the counterweight connecting piece is connected with a counterweight substrate. Compared with a traditional piezoelectric ceramic sensor, vibration mainly depends on the annular metal substrate, the stability of the annular metal substrate is higher than that of ceramic, the annular metal substrate is not prone to being broken during vibration, the situation of ceramic breaking is reduced, and the service life of the device is prolonged.

Description

Technical Field

[0001] This invention belongs to the field of tension measurement technology, specifically relating to racket tension measuring instruments and methods. Background Technology

[0002] The tension of badminton racket strings, also known as the tightness of the strings, is generally expressed in pounds (lbs). Badminton rackets or their packaging usually indicate the appropriate lb range; exceeding this range can damage the racket. For example, Yonex rackets typically indicate a lb range not exceeding 30 lbs. Different strings also have achievable lb limits; exceeding these limits can easily cause breakage. This appropriate range is usually indicated on the string packaging. The string tension varies greatly depending on the stringing machine. A stringing machine claiming 28 lbs might produce a similar tension to another machine's 22 lbs. Therefore, it's essential to choose a consistent store and the same machine and personnel to maintain the appropriate tension for the user. Generally speaking, higher tension (i.e., higher lbs) results in less string elasticity. With the same force, the contact time between the shuttlecock and the racket face is shorter, but the direction of the rebound is more stable. Therefore, if you lack strength or haven't yet mastered generating sufficient power, it's best to use a lower string tension. This allows you to utilize the elasticity of the strings to hit the shuttlecock further, but at the same time, you'll have less control over the direction and depth of your shots. If you have good power generation, a higher string tension is suitable, providing greater control. Generally, beginners and average players use a string tension of 22-24 pounds. Higher tension results in less elasticity (you can think of the racket as a wooden board under sufficient tension). Higher tension also increases the power of your returns. For beginners, 18-19 pounds is recommended for good elasticity, but with slightly reduced control. Those with some experience can increase the tension appropriately; higher tension makes control easier, but it also consumes more energy.

[0003] It is evident that racket tension is crucial for badminton enthusiasts and professional trainers. Furthermore, racket tension can change after stringing due to the material of the strings, potentially resulting in a tension that is no longer optimal for use. Therefore, the ease of racket tension measurement is essential. Currently, racket tension testing is conducted in manufacturing plants or on specialized stringing equipment. This specialized equipment is bulky, expensive, inconvenient to carry, and unsuitable for real-time measurement during regular training. Summary of the Invention

[0004] The purpose of this invention is to provide a racket tension measuring instrument to solve the problem that existing racket tension tests are all conducted in processing plants or on professional stringing equipment. These professional equipment are large, expensive, inconvenient to carry, and cannot be used for real-time measurement during regular training.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A racket tension measuring instrument includes a vibration generating component, a vibration sensing component, a vibration control circuit, a vibration sensing circuit, a processor, and a display module. The vibration generating component includes a first piezoelectric ceramic layer for generating vibration. The vibration control circuit is electrically connected to the first piezoelectric ceramic layer. The vibration sensing component includes a second piezoelectric ceramic sheet for sensing vibration. The second piezoelectric ceramic sheet is electrically connected to the vibration sensing circuit. The vibration sensing circuit is electrically connected to the processor. The processor is electrically connected to the display module. The first and second piezoelectric ceramic layers are sintered on the surface of an annular metal substrate. A counterweight connector, which is cylindrical, is connected to the inner ring of the annular metal substrate. A counterweight base plate is connected to the end of the counterweight connector away from the annular metal substrate.

[0007] According to the above technology, the first piezoelectric ceramic layer and the second piezoelectric ceramic layer are sintered onto the surface of a ring-shaped metal substrate. Compared with traditional piezoelectric ceramic sensors, since the vibration mainly relies on the ring-shaped metal substrate, the stability of the ring-shaped metal substrate is stronger than that of ceramic. It is less prone to breakage during vibration, reducing the likelihood of ceramic breakage and extending the lifespan of the device. Furthermore, this device is small in size and easy to carry, solving the problem in existing technologies where racket tension testing is performed in factories or on professional stringing equipment. Such professional equipment is large, expensive, inconvenient to carry, and unsuitable for real-time measurement during regular training.

[0008] In one possible design, the first piezoelectric ceramic layer and the second piezoelectric ceramic layer are sintered on both sides of the same annular metal substrate, and both the first piezoelectric ceramic layer and the second piezoelectric ceramic layer are annular.

[0009] In one possible design, both the first and second piezoelectric ceramic layers are annular; the annular metal substrate includes a first annular metal substrate and a second annular metal substrate, with the first and second piezoelectric ceramic layers sintered on the sides of the first and second annular metal substrates, respectively; the first piezoelectric ceramic layer and the annular metal substrate on which it is located are located on the counterweight connector at one end away from the counterweight substrate; the second piezoelectric ceramic layer and the annular substrate are located between the annular metal substrate on which the first piezoelectric ceramic layer is located and the counterweight substrate, and have a gap with the counterweight substrate.

[0010] In one possible design, the first piezoelectric ceramic layer and the second piezoelectric ceramic layer are both sintered on the same side surface of the same annular metal substrate. The first piezoelectric ceramic layer is an annular plate, and a notch is provided on the annular plate of the first piezoelectric ceramic layer, at which the second piezoelectric ceramic layer is disposed.

[0011] In one possible design, the annular metal substrate, the counterweight connector, and the counterweight base plate are all made of the same metal. By using the same metal for all these components, the annular metal substrate and the counterweight can be integrally formed or press-fitted together. This method is more robust than bonding ceramics to a metal counterweight base plate, preventing the components that need to vibrate from easily detaching. The annular metal substrate has piezoelectric ceramics sintered on both sides, and the counterweight is directly mounted on the inner circle of the substrate, at a distance from the ceramic structure, thus absorbing a significant amount of impact. This further improves product stability and extends its service life.

[0012] In one possible design, the annular metal substrate, the counterweight connector, and the counterweight base plate are all made of brass.

[0013] In one possible design, the vibration sensing circuit includes an operational amplifier module and an analog-to-digital converter module electrically connected to the operational amplifier module; the operational amplifier module is electrically connected to a second piezoelectric ceramic sheet; and the analog-to-digital converter module is electrically connected to the processor. Using the analog-to-digital converter module to convert analog signals to digital signals results in higher detection accuracy and faster speed.

[0014] In one possible design, the processor is an STM32L152C8T6A processor.

[0015] In a second aspect, the present invention provides a method for measuring racket tension, employing a racket tension measuring instrument as described in the first aspect and any possible design thereof; the method includes the following steps:

[0016] The racket tension measuring instrument is placed on the racket string. Based on the user-input start measurement information, the processor sends a vibration control signal to the vibration control circuit. The vibration control circuit sends a sinusoidal signal to the first piezoelectric ceramic layer. The frequency of the sinusoidal signal gradually increases or decreases. The first piezoelectric ceramic layer vibrates according to the sinusoidal signal, thereby driving the annular metal substrate to vibrate. The vibration of the annular metal substrate drives the second piezoelectric ceramic sheet to vibrate, and simultaneously drives the housing of the racket tension measuring instrument to vibrate. The housing of the racket tension measuring instrument drives the racket string to vibrate. When the frequency of the emitted vibration signal and the frequency of the string are the same, resonance occurs, making the amplitude of the annular metal substrate vibration stronger.

[0017] The vibration sensing circuit senses the vibration of the second piezoelectric ceramic sheet to generate a sensing signal, and transmits the sensing signal to the processor. The processor receives the sensing signal and analyzes the output frequency corresponding to the strongest amplitude in the sensing signal, and outputs the racket string tension value corresponding to the output frequency to the display module for display; thus completing one measurement.

[0018] In the above method, the different tensions of the racket strings lead to different resonant frequencies of the racket net. Based on this, different frequency sinusoidal signals are generated during measurement to detect the net. This method inputs a gradually changing sinusoidal signal to the first piezoelectric ceramic layer, causing it to vibrate at different frequencies. This vibrates the entire annular metal substrate and drives the entire device to vibrate. The device is located on the racket net and utilizes the principle of resonance. When the vibration frequency of the device matches the vibration frequency of the net, resonance occurs, resulting in a stronger amplitude vibration of the annular metal substrate. Since a second piezoelectric ceramic sheet is used as the vibration sensing component, a vibration sensing circuit converts the vibration signal into an electrical signal for the processor. The processor receives the sensing signal and analyzes the output frequency corresponding to the strongest amplitude in the sensing signal. It then outputs the racket net tension value corresponding to the output frequency to the display module for display, thus completing the measurement.

[0019] In one possible design, the vibration sensing circuit senses the vibration of the second piezoelectric ceramic sheet to generate a sensing signal, converts the sensing signal into a digital signal, and then transmits the digital signal to the processor.

[0020] Beneficial effects:

[0021] The racket tension measuring instrument and method provided by this invention employs a first piezoelectric ceramic layer and a second piezoelectric ceramic layer, respectively sintered on both sides of an annular metal substrate. Both the first and second piezoelectric ceramic layers are annular. Compared to traditional piezoelectric ceramic sensors, the vibration is primarily dependent on the annular metal substrate, which offers greater stability than ceramic. This reduces the likelihood of breakage during vibration, extending the device's lifespan. By inputting a gradually changing sinusoidal signal to the first piezoelectric ceramic layer, it vibrates at different frequencies, causing the entire annular metal substrate and the entire device to vibrate. The device is located on the racket and net string, utilizing the principle of resonance. When the device's vibration frequency matches the net string's vibration frequency, resonance occurs, resulting in a stronger amplitude vibration of the annular metal substrate. Since the second piezoelectric ceramic layer serves as the vibration sensing component, a vibration sensing circuit converts the vibration signal into an electrical signal for a processor. The processor receives the sensing signal, analyzes the output frequency corresponding to the strongest amplitude, and outputs the racket and net string tension value corresponding to that frequency to a display module for display, thus completing the measurement. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of the first piezoelectric ceramic layer and the second piezoelectric ceramic layer disposed on the same annular metal substrate in the embodiment, viewed from the right.

[0023] Figure 2 This is a three-dimensional exploded view of the first and second piezoelectric ceramic layers disposed on the same annular metal substrate in the embodiment.

[0024] Figure 3 This is a cross-sectional schematic diagram of the first and second piezoelectric ceramic layers disposed on the same annular metal substrate in the embodiment.

[0025] Figure 4 This is a schematic cross-sectional view of the housing when the first and second piezoelectric ceramic layers are disposed on the same annular metal substrate, as shown in the embodiment.

[0026] Figure 5 This is a cross-sectional structural diagram of the embodiment where the first piezoelectric ceramic layer and the second piezoelectric ceramic layer are disposed on different annular metal substrates;

[0027] Figure 6 This is a schematic diagram of the structure in the embodiment where the first piezoelectric ceramic layer and the second piezoelectric ceramic layer are disposed on the same side of the same annular metal substrate;

[0028] Figure 7 This is a schematic diagram of a specific example in the embodiment, showing a shell with a grab hook.

[0029] Figure 8 This is a schematic diagram of the circuit module connection of the racket tension measuring instrument in the embodiment. Detailed Implementation

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the present invention will be briefly introduced below in conjunction with the accompanying drawings and descriptions of the embodiments or the prior art. Obviously, the following description of the structure of the accompanying drawings is only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. It should be noted that the description of these embodiments is for the purpose of helping to understand the present invention, but does not constitute a limitation of the present invention.

[0031] Example:

[0032] like Figures 1 to 4 ,as well as Figure 8 As shown, this embodiment provides a racket tension measuring instrument, including a vibration generating component, a vibration sensing component, a vibration control circuit, a vibration sensing circuit, a processor, and a display module. The vibration generating component includes a first piezoelectric ceramic layer 2 for generating vibration. The vibration control circuit is electrically connected to the first piezoelectric ceramic layer 2. The vibration sensing component includes a second piezoelectric ceramic sheet 3 for sensing vibration. The second piezoelectric ceramic sheet 3 is electrically connected to the vibration sensing circuit. The vibration sensing circuit is electrically connected to the processor. The processor is electrically connected to the display module. The first piezoelectric ceramic layer 2 and the second piezoelectric ceramic layer 3 are sintered on the surface of an annular metal substrate 1. A counterweight connector 4 is connected to the inner ring of the annular metal substrate. The counterweight connector is cylindrical. A counterweight base plate 5 is connected to the end of the counterweight connector away from the annular metal substrate. In specific implementation, as shown... Figure 4 As shown, the edge of the annular metal substrate contacts the housing 6, allowing the housing 6 to vibrate and transmit the vibration to the racket strings being tested. Specifically, the annular metal substrate has a thickness of 0.08–0.12 mm, an inner diameter of 3–5 mm, and an outer diameter of 19–21 mm; the first and second piezoelectric ceramic layers are the same size, with an inner ring diameter of 7–9 mm and an outer diameter of 15–17 mm. More specifically, the annular metal substrate has a thickness of 0.1 mm, an inner diameter of 4 mm, and an outer diameter of 20 mm; the first and second piezoelectric ceramic layers are the same size, with an inner ring diameter of 8 mm and an outer diameter of 16 mm.

[0033] In one possible implementation, such as Figures 1 to 3 As shown, the first piezoelectric ceramic layer and the second piezoelectric ceramic layer are sintered on both sides of the same annular metal substrate, and both the first piezoelectric ceramic layer and the second piezoelectric ceramic layer are annular.

[0034] In one possible implementation, such as Figure 5 As shown, both the first piezoelectric ceramic layer 2 and the second piezoelectric ceramic layer 3 are annular; the counterweight connector is provided with a first annular metal substrate 7 and a second annular metal substrate 8, and the first piezoelectric ceramic layer and the second piezoelectric ceramic layer are respectively sintered on the sides of the first annular metal substrate and the second annular metal substrate; the first piezoelectric ceramic layer and the annular metal substrate on which it is located are located at one end of the counterweight connector away from the counterweight substrate, and the second piezoelectric ceramic layer and the annular substrate are located between the annular metal substrate on which the first piezoelectric ceramic layer is located and the counterweight substrate, and have a certain gap with the counterweight substrate.

[0035] In one possible design, such as Figure 6 As shown, the first piezoelectric ceramic layer and the second piezoelectric ceramic layer are both sintered on the same side surface of the same annular metal substrate. The first piezoelectric ceramic layer is a notched annular sheet 10, and a notch is provided on the annular plate of the first piezoelectric ceramic layer. The second piezoelectric ceramic layer is a strip sheet 11 disposed at the notch. Sintering on the same side makes sintering easier.

[0036] In one possible implementation, the annular metal substrate, the counterweight connector, and the counterweight base plate are all made of the same metal. Specifically, the annular metal substrate, the counterweight connector, and the counterweight base plate are all made of brass.

[0037] In one possible implementation, such as Figure 8 As shown, the vibration sensing circuit includes an operational amplifier module and an analog-to-digital converter module electrically connected to the operational amplifier module; the operational amplifier module is electrically connected to a second piezoelectric ceramic sheet; and the analog-to-digital converter module is electrically connected to the processor.

[0038] In one possible implementation, the processor is an STM32L152C8T6A processor. In specific implementations, some peripheral circuitry is also included.

[0039] Specifically, the device also has a power module, which includes a battery, a charging circuit, a voltage regulator circuit, a power management circuit, and a power measurement circuit that are electrically connected to the battery. The voltage regulator circuit uses a TPS76933DBV module, and the other circuit modules use existing circuits, which will not be described in detail here. The power module provides power to the device.

[0040] The second aspect of this embodiment provides a method for measuring racket tension, employing the racket tension measuring instrument described in the first aspect and any possible implementation thereof; the method includes the following steps:

[0041] The racket tension measuring instrument is placed on the racket strings. Based on the user-input start measurement information, the processor sends a vibration control signal to the vibration control circuit. The vibration control circuit sends a sinusoidal signal to the first piezoelectric ceramic layer. The frequency of the sinusoidal signal gradually increases, and the first piezoelectric ceramic layer vibrates according to the sinusoidal signal, thereby driving the annular metal substrate to vibrate. The vibration of the annular metal substrate drives the second piezoelectric ceramic sheet to vibrate, and simultaneously drives the housing of the racket tension measuring instrument to vibrate. The housing of the racket tension measuring instrument drives the racket strings to vibrate. When the frequency of the emitted vibration signal and the frequency of the strings are the same, resonance occurs, making the amplitude of the annular metal substrate vibration stronger.

[0042] The vibration sensing circuit senses the vibration of the second piezoelectric ceramic sheet, generating a sensing signal, which is then transmitted to the processor. The processor receives the sensing signal and analyzes the output frequency corresponding to the strongest amplitude in the signal. It then outputs the racket string tension value corresponding to this output frequency to the display module for display; thus completing one measurement. In specific implementation, such as... Figure 7 As shown, the outer shell 7 has at least one hook 9 on its surface. During measurement, the hook 9 is used to hook the racket net string. Of course, two or three hooks can also be provided, such as two hooks that are opposite each other or three hooks that are triangularly distributed. The racket net string can be gripped from different positions, which is convenient for measurement.

[0043] In one possible implementation, the vibration sensing circuit senses the vibration of the second piezoelectric ceramic sheet to generate a sensing signal, converts the sensing signal into a digital signal, and then transmits the digital signal to the processor.

[0044] In summary, the racket tension measuring instrument and method provided in this embodiment employs a first piezoelectric ceramic layer and a second piezoelectric ceramic layer, respectively sintered on both sides of an annular metal substrate. Both the first and second piezoelectric ceramic layers are annular. Compared to traditional piezoelectric ceramic sensors, since vibration primarily relies on the annular metal substrate, the annular metal substrate offers greater stability than ceramic, reducing the likelihood of breakage during vibration and extending the device's lifespan. By inputting a gradually changing sinusoidal signal to the first piezoelectric ceramic layer, different vibrations occur in the first piezoelectric ceramic layer. The vibration of the frequency causes the entire annular metal substrate to vibrate, which in turn drives the entire device to vibrate. The device is located on the racket and net, and it uses the principle of resonance. When the vibration frequency of the device is the same as the vibration frequency of the net, resonance will occur, making the amplitude of the annular metal substrate in the device vibrate stronger. Since a second piezoelectric ceramic sheet is used as a vibration sensing component, the vibration sensing circuit converts the vibration signal into an electrical signal and sends it to the processor. The processor receives the sensing signal and analyzes the output frequency corresponding to the strongest amplitude in the sensing signal, and outputs the racket and net tension value corresponding to the output frequency to the display module for display, thereby completing the measurement.

[0045] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A racket tension measuring instrument, comprising a vibration generating component, a vibration sensing component, a vibration control circuit, a vibration sensing circuit, a processor, and a display module; the vibration generating component includes a first piezoelectric ceramic layer for generating vibration, the vibration control circuit is electrically connected to the first piezoelectric ceramic layer, the vibration sensing component includes a second piezoelectric ceramic sheet for sensing vibration, the second piezoelectric ceramic sheet is electrically connected to the vibration sensing circuit, the vibration sensing circuit is electrically connected to the processor, and the processor is electrically connected to the display module, characterized in that... The first piezoelectric ceramic layer and the second piezoelectric ceramic layer are sintered on the surface of an annular metal substrate. A counterweight connector is connected to the inner ring of the annular metal substrate. The counterweight connector is cylindrical. A counterweight base plate is connected to the end of the counterweight connector away from the annular metal substrate.

2. The racket tension measuring instrument according to claim 1, characterized in that, The first piezoelectric ceramic layer and the second piezoelectric ceramic layer are sintered on both sides of the same annular metal substrate, and both the first piezoelectric ceramic layer and the second piezoelectric ceramic layer are annular.

3. The racket tension measuring instrument according to claim 1, characterized in that, Both the first piezoelectric ceramic layer and the second piezoelectric ceramic layer are annular; the annular metal substrate includes a first annular metal substrate and a second annular metal substrate, and the first piezoelectric ceramic layer and the second piezoelectric ceramic layer are respectively sintered on the sides of the first annular metal substrate and the second annular metal substrate; The first piezoelectric ceramic layer and the annular metal substrate on which it is located are located at one end of the counterweight connector away from the counterweight substrate; the second piezoelectric ceramic layer and the annular substrate are located between the annular metal substrate on which the first piezoelectric ceramic layer is located and the counterweight substrate, and have a gap with the counterweight substrate.

4. The racket tension measuring instrument according to claim 1, characterized in that, The first piezoelectric ceramic layer and the second piezoelectric ceramic layer are both sintered on the same side surface of the same annular metal substrate. The first piezoelectric ceramic layer is an annular plate, and a notch is provided on the annular plate of the first piezoelectric ceramic layer. The second piezoelectric ceramic layer is disposed at the notch.

5. The racket tension measuring instrument according to claim 1, characterized in that, The annular metal substrate, the counterweight connector, and the counterweight base plate are all made of the same metal.

6. The racket tension measuring instrument according to claim 1, characterized in that, The annular metal substrate, the counterweight connector, and the counterweight base plate are all made of brass.

7. The racket tension measuring instrument according to claim 1, characterized in that, The vibration sensing circuit includes an operational amplifier module and an analog-to-digital converter module electrically connected to the operational amplifier module; the operational amplifier module is electrically connected to a second piezoelectric ceramic sheet; and the analog-to-digital converter module is electrically connected to the processor.

8. The racket tension measuring instrument according to claim 1, characterized in that, The processor is an STM32L152C8T6A processor.

9. A method for measuring racket tension, characterized in that, The method employs the racket tension measuring instrument as described in any one of claims 1 to 8; the method includes the following steps: The racket tension measuring instrument is placed on the racket strings. Based on the user-input start measurement information, the processor sends a vibration control signal to the vibration control circuit. The vibration control circuit sends a sinusoidal signal to the first piezoelectric ceramic layer. The frequency of the sinusoidal signal gradually increases, and the first piezoelectric ceramic layer vibrates according to the sinusoidal signal, thereby driving the annular metal substrate to vibrate. The vibration of the annular metal substrate drives the second piezoelectric ceramic sheet to vibrate, and simultaneously drives the housing of the racket tension measuring instrument to vibrate. The housing of the racket tension measuring instrument drives the racket strings to vibrate. When the frequency of the emitted vibration signal and the frequency of the strings are the same, resonance occurs, making the amplitude of the annular metal substrate vibration stronger. The vibration sensing circuit senses the vibration of the second piezoelectric ceramic sheet to generate a sensing signal, and transmits the sensing signal to the processor. The processor receives the sensing signal and analyzes the output frequency corresponding to the strongest amplitude in the sensing signal, and outputs the racket string tension value corresponding to the output frequency to the display module for display, so as to complete a measurement.

10. The racket tension measurement method according to claim 9, characterized in that, The vibration sensing circuit senses the vibration of the second piezoelectric ceramic sheet to generate a sensing signal, converts the sensing signal into a digital signal, and then transmits the digital signal to the processor.

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