Independent full-bridge detection disc claw type power meter

Abstract

The invention relates to an independent full-bridge detection disc claw type power meter, which belongs to the technical field of power detection, and comprises a disc claw main body, N connecting shafts, a first connecting shaft and a second connecting shaft, n detection units; each detection unit comprises two strain gauges; each strain gauge comprises two resistors; each detection unit is arranged on a connecting shaft, and a strain gauge is arranged on the opposite surface of each connecting shaft; the two strain gauges in each detection unit are connected, so that the four resistors of each detection unit form a full-bridge circuit; the mainboard is connected with the output ends of the N full-bridge circuits; wherein each full-bridge circuit is used for detecting the torque value of the corresponding connecting shaft; the mainboard is used for determining a total torque value according to the N torque values and calculating power according to the total torque value. Through the mode of independent full-bridge measurement of each connecting shaft, the measurement influence caused by machining errors of different shafts is reduced, the measurement precision is further improved, and the reliability of measurement data of the disc claw type power meter is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of power measurement and relates to a disc claw type power meter with independent full bridge detection. Background Art

[0002] In recent years, with the development of intelligent cycling devices, sports monitoring systems, and electric assist bicycles, the demand for high-precision real-time power measurement has grown rapidly. As a core component for cycling analysis and training feedback, a power meter mainly measures pedaling torque and cadence to calculate the mechanical power output by a cyclist in real time, helping to evaluate sports performance and regulate training intensity.

[0003] The disc claw type power meter is a commonly used power calculation device on cycling equipment. The disc claw type power meter is a high-precision device for measuring the power of a rotating mechanical shaft. Through a disc claw structure clamped on the transmission shaft, it uses strain gauges to detect minute deformations of the connecting shaft and calculates power in combination with the rotational speed.

[0004] The structure of the existing disc claw type power meter is as follows: a strain gauge is provided on each of the four connecting shafts, and the resistances of the four strain gauges are connected in series to form a full bridge. When a cyclist applies force, the connecting shaft is deformed by torque, which in turn causes the strain gauge to be deformed by force, resulting in a change in the resistance of the strain gauge; the change in resistance causes a change in the current or voltage passing through the resistance. By performing analog-to-digital conversion on the electrical signal changes of the strain gauge, power data is finally output.

[0005] However, through research, it is found that there are processing consistency problems in the production of the disc claw structure, that is, there are slight differences in each connecting shaft during the production process of some disc claw structures. The current connection method connects the strain gauge resistances of each connecting shaft in series to form a full bridge, which is easily affected by process errors during the processing of different connecting shafts, thereby affecting the measurement accuracy and reducing the reliability of the measurement data. Summary of the Invention

[0006] To solve the above problems in the prior art, the present invention provides a disc claw type power meter with independent full bridge detection.

[0007] To achieve the above object, the technical solution adopted by the present invention is: In a first aspect, the present invention provides a disk claw type power meter for independent full-bridge detection, comprising: a disk claw main body including N connecting shafts, where N is a positive integer; N detection units, each of which includes two strain gauges, and each strain gauge includes two resistors. Each detection unit is respectively arranged on a connecting shaft, and one strain gauge is respectively arranged on the opposite surfaces of each connecting shaft. The two strain gauges in each detection unit are connected so that the four resistors of each detection unit form a full-bridge circuit; a main board connected to the output ends of the N full-bridge circuits. Each full-bridge circuit is used to detect the torque value of the connecting shaft where it is located, and the main board is used to determine the total torque value according to the N torque values and calculate the power according to the total torque value.

[0008] Optionally, N is four, and the included angle between two adjacent connecting shafts among the four connecting shafts is 90 degrees.

[0009] Optionally, the main board is further specifically used to determine the total torque value through the following formula, including: ; where represents the total torque value; represents the torque value of the th connecting shaft; represents the torque value of the th connecting shaft; represents the sensitivity coefficient of the th connecting shaft; represents the non-linear coupling coefficient between the th connecting shaft and the th connecting shaft; represents a bias term used to compensate for zero drift.

[0010] Optionally, the main board is further used to obtain a first torque curve and a second torque curve, and determine the alternating state of the user's left and right feet during riding according to the peak changes of the first torque curve and the second torque curve. The first torque curve corresponds to a first connecting shaft, and the second torque curve corresponds to a second connecting shaft. The first connecting shaft and the second connecting shaft are two relatively arranged connecting shafts.

[0011] Optionally, the disk claw type power meter is installed on a riding device and is located on the right side of the chainring. The first connecting shaft is closer to the right crank of the riding device than the second connecting shaft. The main board is further used to determine that the user's right foot is exerting force when the peak of the first torque curve is higher than the peak of the second torque curve, and determine that the user's left foot is exerting force when the peak of the second torque curve is higher than the peak of the first torque curve.

[0012] Optionally, the main board is further configured to determine a waveform period according to the peaks of the first torque curve and / or the second torque curve; determine the cadence of the user based on the waveform period, and calculate an angular velocity based on the cadence of the user; correspondingly, the main board is further configured to calculate power based on the angular velocity and the total torque value.

[0013] Optionally, the main board is further configured to determine the current ambient temperature; compensate the total torque value based on the current ambient temperature and a temperature compensation curve, and calculate power based on the compensated total torque value; wherein, the temperature compensation curve is determined by placing the disc claw type power meter in a temperature chamber and setting different temperature values to detect the disc claw type power meter.

[0014] Optionally, when it is detected that the riding device is in a stationary state, if the torque values of the N full-bridge circuits are collected, the main board is further configured to use the torque values of the N full-bridge circuits as zero values.

[0015] Optionally, the output end of each full-bridge circuit is connected to the main board through a twisted pair wire.

[0016] Optionally, the main board includes: N operational amplifier modules, an analog-to-digital conversion module, and a processing chip; wherein, each of the N full-bridge circuits is connected to an operational amplifier module, and each operational amplifier module is configured to amplify and filter the measurement value of the full-bridge circuit connected thereto; the analog-to-digital conversion module is connected to the N operational amplifier modules and is configured to perform analog-to-digital conversion of signals to obtain N torque values; the processing chip is connected to the analog-to-digital conversion module and is configured to determine the total torque value according to the N torque values and calculate power according to the total torque value.

[0017] The beneficial effects of the disk claw type power meter with independent full-bridge detection provided by this application at least include: Considering that there will be machining differences in each connecting shaft during the machining process of the current disk claw structure, especially for aluminum alloy disk claws, if the strain gauges on each connecting shaft are connected in series to form a full bridge, it is easily affected by the process errors during the machining of different connecting shafts, thereby affecting the measurement accuracy and reducing the reliability of the measurement data. Therefore, this application provides a disk claw type power meter with independent full-bridge detection, which sets corresponding detection units according to the number of connecting shafts. Each detection unit includes two strain gauges, and each strain gauge includes two resistors. Then, the four resistors of each detection unit are connected in series to form a full-bridge circuit. In other words, a full-bridge circuit for detection is set for each connecting shaft respectively, and each full-bridge circuit can measure the deformation amount (corresponding torque value) of the connecting shaft where it is located. That is, each connecting shaft can perform full-bridge measurement independently. After each connecting shaft performs full-bridge measurement independently, the total torque value is calculated, and the power is calculated. In this way, on the one hand, it can achieve independent detection of each connecting shaft, which helps to finely evaluate the user's riding performance (the existing one can only calculate the total torque). On the other hand, the full-bridge circuit is constructed by connecting the resistors on the same connecting shaft in series, and the deformation amounts detected by the strain gauges on the same connecting shaft are the same. That is, through the form of independent full-bridge measurement for each connecting shaft, the measurement influence brought by the machining errors of different shafts is reduced, thereby improving the measurement accuracy and the reliability of the measurement data of the disk claw type power meter. Description of the Drawings

[0018] Figure 1 FIG. 6 is a schematic structural diagram of a disk claw type power meter with independent full-bridge detection provided by an embodiment of the present invention from a first perspective; Figure 2 FIG. 9 is a schematic structural diagram of a disk claw type power meter with independent full-bridge detection provided by an embodiment of the present invention from a second perspective; Figure 3 FIG. 12 is a schematic circuit diagram of a full-bridge circuit composed of one connecting shaft provided by an embodiment of the present invention; Figure 4 FIG. 15 is a schematic connection relationship diagram of a disk claw type power meter with independent full-bridge detection provided by an embodiment of the present invention; Figure 5 FIG. 18 is a schematic diagram of a torque curve provided by an embodiment of the present invention; Figure 6 FIG. 21 is a schematic diagram of a torque comparison curve after temperature compensation provided by an embodiment of the present invention; Figure 7 FIG. 24 is a schematic diagram of the component modules of a main board provided by an embodiment of the present invention; Figure 8 FIG. 27 is a schematic partial circuit diagram corresponding to four connecting shafts provided by an embodiment of the present invention; Reference Signs: 100 - Disc Claw Power Meter; 10 - Disc Claw Main Body; 101 - Connecting Shaft; 20 - Detection Unit; 201 - Strain Gauge; 30 - Main Board; 301 - Operational Amplifier Module; 302 - Analog - to - Digital Conversion Module; 303 - Processing Chip. Detailed Embodiment

[0019] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0020] The structure of the existing disc claw power meter is as follows: One strain gauge is provided on each of the four connecting shafts, and the resistors of the four strain gauges are connected in series to form a full - bridge. When a rider applies force, the connecting shaft is deformed by torque, and then the strain gauge is deformed by the force, resulting in a change in the resistance of the strain gauge; the change in resistance causes a change in the current or voltage passing through the resistor. By performing analog - to - digital conversion on the electrical signal changed by the strain gauge, power data is finally output.

[0021] However, through research, it is found that there are problems with processing consistency in the production of the disc claw structure. That is, there are slight differences in each connecting shaft during the production process of some disc claw structures. The current connection method connects the strain gauge resistors of each connecting shaft in series to form a full - bridge, which is easily affected by the process errors during the processing of different connecting shafts, thereby affecting the measurement accuracy and reducing the reliability of the measurement data.

[0022] In view of the above problems, the present application provides the following embodiments to solve: Please refer to Figures 1 to 4 , an embodiment of the present application provides a disc claw power meter 100 with independent full - bridge detection, including: a disc claw main body 10, N detection units 20, and a main board 30.

[0023] Among them, the disc claw main body 10 includes N connecting shafts 101.

[0024] Among them, each detection unit 20 includes two strain gauges 201. Each strain gauge 201 includes two resistors.

[0025] The two resistors of each strain gauge 201 are connected in series. Each detection unit 20 is respectively arranged on a connecting shaft 101, and one strain gauge 201 is respectively arranged on the opposite surfaces of each connecting shaft 101.

[0026] That is, each detection unit 20 corresponds to one connecting shaft 101 respectively. The number of detection units 20 is equal to the number of connecting shafts 101.

[0027] Specifically, asFigures 1 to 2 As shown Figure 1 is the first face of the disk claw power meter 100 Figure 2 is the second face of the disk claw power meter 100, and the two faces are opposite faces. For any one of the connecting shafts 101, a strain gauge 201 is arranged on its first face, and a strain gauge 201 is also arranged on its second face. The first face of the connecting shaft 101 corresponds to the first face of the disk claw power meter 100, and the second face of the connecting shaft 101 corresponds to the second face of the disk claw power meter 100.

[0028] It can be understood that a strain gauge 201 is attached to each of the front and back faces of each connecting shaft 101, and the two strain gauges 201 on each connecting shaft 101 form a detection unit 20.

[0029] In the embodiments of the present application, N is a positive integer. For example, N can be 3, 4, 5, etc.

[0030] In one embodiment, N can also specifically be a positive integer greater than or equal to 4.

[0031] Specifically, when N is 4, the disk claw body 10 includes 4 connecting shafts 101. The disk claw power meter 100 includes 4 detection units 20.

[0032] For each detection unit 20, the two strain gauges 201 included therein are connected so that the four resistors of each detection unit 20 form a full-bridge circuit. The full-bridge circuit formed by each detection unit 20 can independently measure the deformation amount of the connecting shaft 101 where it is located.

[0033] Such as Figure 3 shown Figure 3 presents a schematic diagram of the full-bridge circuit formed after arranging a strain gauge on each of the front and back faces of any one of the connecting shafts.

[0034] The full-bridge circuit is composed of a resistor R1, a resistor R2, a resistor R3, and a resistor R4. Among them, the resistor R1 and the resistor R2 are two resistors in a strain gauge on the front face of the connecting shaft. The resistor R3 and the resistor R4 are two resistors in a strain gauge on the back face of the connecting shaft.

[0035] In terms of the connection relationship, the first end of resistor R1 is connected to the first end of resistor R3, and the first ends of resistor R1 and resistor R3 are also connected to the power supply terminal (VCC). The second end of resistor R1 is connected to the first end of resistor R2, the second end of resistor R3 is connected to the first end of resistor R4; the second end of resistor R2 is connected to the second end of resistor R4; the second ends of resistor R2 and resistor R4 are commonly grounded (GND); a first output terminal is connected between the second end of resistor R1 and the first end of resistor R2, and a second output terminal is connected between the second end of resistor R3 and the first end of resistor R4.

[0036] Next, taking Figure 3 as an example, the detection principle of the full-bridge circuit in a single connecting shaft will be described. Assume that the current connecting shaft is under the force of the user stepping on the pedal, and the rotation of the connecting shaft is clockwise. At this time, the resistor R1 on the front side of the connecting shaft is stretched, the resistor R1 becomes longer, and the value of resistor R1 increases. At the same time, the resistor R2 is compressed, the resistor R2 becomes shorter, and the value of resistor R2 decreases. The change of the resistor R3 on the reverse side of the connecting shaft is the same as that of resistor R1, and the change of the resistor R4 on the reverse side of the connecting shaft is the same as that of resistor R2. Since the resistance value of the full-bridge circuit has changed, the corresponding electrical signal change can be obtained according to the first output terminal and the second output terminal to determine the torque value of the connecting shaft.

[0037] In other words, during the periodic process of the user stepping on the pedal, one of the two resistors on the same side is in tension and the other is in compression. The resistor will undergo micron-scale expansion and contraction during this process. When in tension, the resistor becomes longer and thinner, and the resistance value increases. When in compression, it becomes shorter and thicker, and the resistance value decreases. The full-bridge circuit can accurately capture the tiny changes and output different electrical signals accordingly.

[0038] Please refer to Figure 4 , where the main board 30 is connected to the output terminals of N full-bridge circuits. Each full-bridge circuit is used to detect the torque value of its respective connecting shaft, and the main board 30 is used to determine the total torque value based on the N torque values and calculate the power based on the total torque value.

[0039] In summary, considering that there are machining differences for each connecting shaft during the machining process of the current disk claw structure, especially for the aluminum alloy disk claw, if the strain gauges on each connecting shaft are connected in series to form a full bridge, it is easily affected by the process errors during the machining of different connecting shafts, thereby affecting the measurement accuracy and reducing the reliability of the measurement data. Therefore, the embodiment of the present application provides a disk claw type dynamometer 100 with independent full bridge detection. It sets corresponding detection units 20 according to the number of connecting shafts 101. Each detection unit 20 includes two strain gauges 201, and each strain gauge 201 includes two resistors. Then, the four resistors of each detection unit are connected in series to form a full bridge circuit. In other words, a full bridge circuit for detection is set for each connecting shaft 101 respectively, and each full bridge circuit can measure the deformation amount (corresponding to the torque value) of the connecting shaft 101 where it is located. That is, each connecting shaft 101 can perform full bridge measurement independently. After each connecting shaft 101 performs full bridge measurement independently, the total torque value is calculated, and then the power is calculated. In this way, on the one hand, it can achieve independent detection of each connecting shaft 101, which helps to evaluate the user's riding performance in a refined manner (the existing one can only calculate the total torque). On the other hand, the full bridge circuit is constructed by connecting the resistors on the same connecting shaft 101 in series, and the deformation amounts detected by the strain gauges 201 on the same connecting shaft 101 are the same. That is, through the form of independent full bridge measurement of each connecting shaft 101, the measurement influence brought by the machining errors of different shafts is reduced, thereby improving the measurement accuracy and the reliability of the measurement data of the disk claw type dynamometer.

[0040] In one embodiment, the disk claw type dynamometer 100 includes four connecting shafts 101.

[0041] Among them, the angle between two adjacent connecting shafts 101 among the four connecting shafts is 90 degrees, thereby realizing the spatial symmetry of the four connecting shafts 101 and improving the measurement accuracy.

[0042] In addition, during the research, it is found that the forces on the four connecting shafts 101 are non-uniform (some are large and some are small), and the riding force application points of different users are also different, resulting in a non-linear coupling situation in the forces on the four connecting shafts 101, and the overall output cannot be accurately represented by a simple linear combination. Therefore, this embodiment designs the following formula to determine the total torque value. The specific formula includes: ; Among them, represents the total torque value; represents the torque value of the th connecting shaft; represents the torque value of the th connecting shaft; represents the sensitivity coefficient of the th connecting shaft; represents the The nonlinear coupling coefficient of the connecting shafts; represents a bias term used to compensate for zero drift.

[0043] It should be noted that during calibration, a known stepped torque is applied, and the values of the four connecting shafts at each step are recorded. The recorded experimental data is substituted into the above equation, and the optimal linear term, quadratic term coefficients, and constant term are obtained through least squares fitting to obtain the optimal solution for calculating the above coefficients.

[0044] It can be seen that in this embodiment, by linearly weighting the four full-bridge signals with sensitivity weights respectively, the independent contributions of each connecting shaft are accurately expressed. At the same time, a signal cross product and a coupling weight are introduced to construct a non-linear term, comprehensively modeling the mechanical coupling relationship between the shaft arms. Combining with the bias term obtained by regression fitting, structural errors such as system zero drift are effectively compensated, and high-precision estimation of torque output is achieved.

[0045] Optionally, the main board 30 is further configured to obtain a first torque curve and a second torque curve, and determine the alternating state of the user's left and right feet during riding according to the peak changes of the first torque curve and the second torque curve; wherein, the first torque curve corresponds to the first connecting shaft, and the second torque curve corresponds to the second connecting shaft; the first connecting shaft and the second connecting shaft are two relatively arranged connecting shafts.

[0046] That is, the embodiment of the present application provides a method for detecting the force states of the user's left and right feet by detecting the peak changes of the torque curves of two relatively arranged connecting shafts.

[0047] The specific determination method can be to install a disc claw type power meter on the riding device and on the right side of the chainring. The first connecting shaft is closer to the right crank of the riding device than the second connecting shaft; then the main board is further configured to determine that the user's right foot is exerting force when the peak of the first torque curve is higher than the peak of the second torque curve, and determine that the user's left foot is exerting force when the peak of the second torque curve is higher than the peak of the first torque curve.

[0048] Please refer to Figure 5 , as Figure 5 shown, the first torque curve and the second torque curve are torque change diagrams of two diagonal connecting shafts. The horizontal axis represents time, and the vertical axis represents torque. When the peak of the first torque curve is higher than the second torque curve, it indicates that the right foot is exerting force, and when the peak of the second torque curve is higher than the first torque curve, it indicates that the left foot is exerting force.

[0049] The above-mentioned cycling equipment can be a bicycle, a bike trainer, etc. Of course, in other embodiments, the spider power meter can also be installed on the left side of the chainring, and the first connecting shaft can be closer to the left crank of the cycling equipment compared to the second connecting shaft for calibration to detect the force exerted by the user's left and right feet. There is no limitation on this.

[0050] Optionally, the main board is further configured to determine a waveform period based on the peaks of the first torque curve and / or the second torque curve; based on the waveform period, determine the user's cadence, and calculate the angular velocity based on the user's cadence.

[0051] It should be noted that when cycling, the user's left and right feet alternately step on the pedals to form a sine-shaped force waveform, that is, the above-mentioned first torque curve and second torque curve are a waveform period T (of course, the waveform period T can also be determined only based on the first torque curve or the second torque curve).

[0052] Then, the user's cadence RPM can be calculated based on the waveform period T. The specific calculation formula is: . After determining the cadence RPM, according to the formula: the angular velocity can be calculated. .

[0053] Correspondingly, the main board is further configured to calculate the power P based on the angular velocity and the total torque value.

[0054] The calculation formula for the power P is: P .

[0055] It should be noted that in the prior art, it is necessary to combine an angular velocity sensor, etc. to jointly calculate the power. In this embodiment, however, the cadence can be calculated based on the torque curves of two oppositely arranged connecting shafts, and the angular velocity can be calculated based on the cadence, without the need to set other sensors, which can save the product cost.

[0056] In summary, this embodiment provides left and right foot and cadence detection. By comparing the detection data waveforms of different full bridges, the force exerted by the left and right feet is judged, and then the balance of the left and right feet (an important index for cycling posture and training) can be analyzed, and the pedaling cycle (or frequency) can be quickly obtained, and the actual power can be quickly detected.

[0057] Optionally, the main board 30 is further configured to determine the current ambient temperature; based on the current ambient temperature and the temperature compensation curve, compensate the total torque value, and calculate the power based on the compensated total torque value.

[0058] Among them, the temperature compensation curve is determined by placing the spider power meter in a temperature chamber and setting different temperature values to detect the spider power meter.

[0059] If the disk claw type power meter is placed in a temperature chamber with a temperature range of -20°C to 50°C, record the output values and the corresponding temperatures, and the temperature change curve of each disk claw can be obtained. By compensating the data at different temperatures, the final torque data can be obtained.

[0060] Exemplarily, in a controllable temperature environment of -20°C to 50°C, the working temperature of the device can be monitored in real time through a temperature sensor; at each preset temperature, calculate the total torque value; compare the total torque values at different temperatures with the corresponding temperatures, and use the fitting method to obtain the temperature weight factor; subtract the standard working temperature from the current actual temperature, multiply the temperature difference by the temperature weight factor and then add a constant one to obtain the temperature adjustment factor; multiply the total torque value at the current temperature by the temperature adjustment factor to obtain the torque compensation value; record the torque compensation value and its corresponding temperature obtained at each temperature point, analyze the change of the output total torque value at different temperatures, and obtain the temperature change curve to analyze the influence of temperature on torque.

[0061] Among them, the torque compensation value (corresponding to the temperature compensation curve) is determined by the following formula: ; In the formula, represents the torque compensation value at temperature T; represents the total torque value calculated at temperature T; represents the current actual temperature, set between -20 degrees Celsius and 50 degrees Celsius; represents the standard working temperature of 25 degrees Celsius; represents the temperature weight factor obtained by measuring the errors of known torques at multiple temperature points and performing a linear regression fit of the relative deviation to the temperature difference, with a range between 0.001 and 0.005.

[0062] Please refer to Figure 6 Figure 6 shows the curve of the original torque value and the torque value after compensation at different temperatures, Figure 6 where the horizontal axis is the temperature and the vertical axis is the torque value.

[0063] In summary, in this embodiment, by monitoring the operating temperature of the device in real time and collecting torque data in the temperature range of -20°C to 50°C, combining with the temperature weight factor obtained by fitting, constructing a temperature compensation curve, and dynamically compensating for the torque error caused by temperature changes, the adaptability and measurement accuracy of the system under multiple environmental conditions are significantly improved.

[0064] Optionally, the main board 30 is further configured to, when detecting that the riding device is in a stationary state, if the torque values of N full-bridge circuits are collected, use the torque values of the N full-bridge circuits as the zero point values.

[0065] ​Considering the existing claw-type power meters, none of them can cope with the plastic deformation of the connecting shaft. For example, when the claw-type power meter is over-pedaled, impacted, or falls, it may cause the connecting shaft to undergo plastic deformation within a certain range. If this plastic deformation does not affect the use of the product (bicycle or cycling platform), the rider will usually continue to use the product (bicycle or cycling platform). However, the occurrence of plastic deformation at this time will cause a basic reading to appear in the power calculation, resulting in an error between the measurement result and the actual data. Therefore, in this embodiment, through timed detection, the strain data output under static conditions is detected, and the static detection data (torque value under static conditions) read is output as a 0-point check, and the power calculation process is re-adapted, so that the claw-type power meter can still accurately output accurate power even after plastic deformation occurs.

[0066] Of course, you can also set a static detection time, such as 5 minutes or 10 minutes. Specifically, through timed detection, the strain data output under static conditions (such as no data change for more than 10 minutes) is detected, and the static detection data (torque value under static conditions) read is output as the zero-point calibration.

[0067] Optionally, the output end of each full-bridge circuit is connected to the mainboard via a twisted pair cable.

[0068] Considering the spatially disparate locations of the multiple connecting arms in current claw-type power meters, the long wires that form the full-bridge circuit are susceptible to electromagnetic interference, which can lead to uncontrollable interference signals. Therefore, in this embodiment, the outputs of the multiple strain gauges are transmitted using twisted-pair cables. Since the multiple strain gauges are located on the same connecting arm and are therefore essentially spatially co-located, the individual wire lengths (the untwisted portions of the twisted pair) are very short when transmitting signals via the twisted-pair cables, significantly reducing the impact of external electromagnetic interference.

[0069] Optionally, see Figure 7 The main board 30 includes: N operational amplifier modules 301 , an analog-to-digital conversion module 302 and a processing chip 303 .

[0070] The N full-bridge circuits are respectively connected to an operational amplifier module 301 , and each operational amplifier module 301 is used to amplify and filter the measurement value of the full-bridge circuit to which it is connected.

[0071] The analog-to-digital conversion module 302 is connected to the N operational amplifier modules 301 and is used to perform analog-to-digital conversion of the signal to obtain N torque values.

[0072] The processing chip 303 is connected to the analog-to-digital conversion module, and is configured to determine a total torque value according to the N torque values, and calculate power according to the total torque value.

[0073] N full-bridge circuits can share the power supply and GND. The signal lines in the same full-bridge circuit are connected to the main board 30 through twisted pairs. There are N operational amplifier modules 301 on the main board 30. The measured values of the N full-bridge circuits are amplified and filtered by the N operational amplifier modules 301, and then the amplified signals are input into the analog-to-digital conversion module 302 to be converted into the final digital signals. Finally, the processing chip 303 synthesizes the N processed digital signals into a total effective value, that is, the total torque value, through an algorithm and calculates the power.

[0074] Please refer to Figure 8 , as an example, Figure 8 shows the partial connection relationship when four connecting shafts 101 are included. Among them, the detection unit 20 corresponding to the first connecting shaft 101 includes resistor R1, resistor R2, resistor R3, and resistor R4, and the first connecting shaft 101 corresponds to the first operational amplifier module 301 on the main board 30. The detection unit 20 corresponding to the second connecting shaft 101 includes resistor R5, resistor R6, resistor R7, and resistor R8, and the second connecting shaft 101 corresponds to the second operational amplifier module 301 on the main board 30. The detection unit 20 corresponding to the third connecting shaft 101 includes resistor R9, resistor R10, resistor R11, and resistor R12, and the third connecting shaft 101 corresponds to the third operational amplifier module 301 on the main board 30. The detection unit 20 corresponding to the fourth connecting shaft 101 includes resistor R13, resistor R14, resistor R15, and resistor R16, and the fourth connecting shaft 101 corresponds to the fourth operational amplifier module 301 on the main board 30.

[0075] In summary, in the embodiments of the present application, a complete solution from signal acquisition, torque calculation, temperature compensation to power output is provided, which ensures the high-quality acquisition and stable conversion of strain signals, overcomes the influence of inconsistent errors of different connecting shafts, and realizes accurate torque and power estimation; the temperature compensation strategy can dynamically correct the measurement offset caused by environmental temperature differences to ensure the reliability of the system under complex working conditions; at the same time, it also provides real-time analysis of the pedaling rhythm and left and right foot recognition, and accurately calculates the final power by back-calculating the angular velocity and torque compensation value, providing intelligent and refined cycling feedback and training evaluation for users, and overall improving the comprehensive performance of the system in terms of measurement accuracy, environmental adaptability, and interaction intelligence.

[0076] In addition, in the description of the present application specification and the appended claims, the terms "first", "second", "third", etc. are only used for distinguishing descriptions and cannot be understood as indicating or implying relative importance.

[0077] Reference to "one embodiment" or "some embodiments" etc. described in the specification of the present application means that a specific feature, structure or characteristic described in connection with that embodiment is included in one or more embodiments of the present application. Thus, statements such as "in one embodiment", "in some embodiments", "in other some embodiments", "in still other embodiments" etc. that appear in different places in this specification do not necessarily all refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways. The terms "comprising", "including", "having" and their variants all mean "including but not limited to", unless otherwise specifically emphasized in other ways.

[0078] In the description of the embodiments of the present invention, it should be understood that the orientation or positional relationship indicated by terms such as "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "center", "top", "bottom", "top part", "bottom part", "inner", "outer", "inner side", "outer side" etc.

[0079] In the description of the embodiments of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "mounted", "connected", "joined", "assembled" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be directly connected, or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0080] In the description of the embodiments of the present invention, specific features, structures, materials or characteristics can be combined in a suitable manner in any one or more embodiments or examples.

[0081] In the description of the embodiments of the present invention, it should be understood that "-" and "~" represent the range between two numerical values, and this range includes the endpoints. For example: "A - B" represents a range greater than or equal to A and less than or equal to B. "A ~ B" represents a range greater than or equal to A and less than or equal to B.

[0082] In the description of the embodiments of the present invention, the term "and / or" herein is merely a description of the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " herein generally represents an "or" relationship between the associated objects before and after.

[0083] Although embodiments of the present invention have been shown and described, those of ordinary skill in the art will appreciate that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A disc claw type power meter for independent full-bridge detection, characterized in that, Comprising: A disk claw body, including N connecting shafts; N is a positive integer; N detection units; wherein, each detection unit includes two strain gauges; each strain gauge includes two resistors; each detection unit is respectively arranged on a connecting shaft, and one strain gauge is respectively arranged on the opposite surfaces of each connecting shaft; Wherein, the two strain gauges in each detection unit are connected so that the four resistors of each detection unit form a full-bridge circuit; A main board, connected to the output ends of the N full-bridge circuits; wherein, each full-bridge circuit is used to detect the torque value of the connecting shaft where it is located; the main board is used to determine the total torque value according to the N torque values and calculate the power according to the total torque value.

2. The disk claw type power meter for independent full-bridge detection according to claim 1, wherein N is four; Wherein, the included angle between two adjacent connecting shafts among the four connecting shafts is 90 degrees.

3. The disc claw type power meter for independent full bridge detection according to claim 2, characterized in that, The main board is also specifically used to determine the total torque value through the following formula, including: ； Among them, represents the total torque value; represents the torque value of the th connecting shaft; represents the torque value of the th connecting shaft; represents the sensitivity coefficient of the th connecting shaft; represents the non-linear coupling coefficient between the th connecting shaft and the th connecting shaft; represents the bias term used to compensate for zero drift.

4. The pawl-type power meter for independent full-bridge detection according to claim 2, wherein, The main board is also used to obtain a first torque curve and a second torque curve, and determine the alternating state of the user's left and right feet during riding according to the peak changes of the first torque curve and the second torque curve; Wherein, the first torque curve corresponds to a first connecting shaft, and the second torque curve corresponds to a second connecting shaft; the first connecting shaft and the second connecting shaft are two relatively arranged connecting shafts.

5. The disk claw type power meter for independent full-bridge detection according to claim 4, wherein The disk claw type power meter is installed on the riding device and is located on the right side of the chainring, and the first connecting shaft is closer to the right crank of the riding device than the second connecting shaft; The main board is also used to determine that the user's right foot is exerting force when the peak of the first torque curve is higher than the peak of the second torque curve, and determine that the user's left foot is exerting force when the peak of the second torque curve is higher than the peak of the first torque curve.

6. The disc claw type power meter for independent full-bridge detection according to claim 4, characterized in that, The main board is also used to determine the waveform period according to the peak of the first torque curve and / or the second torque curve; based on the waveform period, determine the user's cadence, and calculate the angular velocity based on the user's cadence; Correspondingly, the main board is also used to calculate the power based on the angular velocity and the total torque value.

7. The disc claw type power meter for independent full-bridge detection according to claim 1, characterized in that, The main board is also used to determine the current ambient temperature; compensate the total torque value based on the current ambient temperature and the temperature compensation curve, and calculate the power based on the compensated total torque value; Wherein, the temperature compensation curve is determined by placing the disk claw type power meter in a temperature chamber and setting different temperature values to detect the disk claw type power meter.

8. The disc claw type power meter for independent full-bridge detection according to claim 1, characterized in that The main board is also used to, when detecting that the riding device is in a stationary state, if the torque values of the N full-bridge circuits are collected, use the torque values of the N full-bridge circuits as zero point values.

9. The pawl-type power meter for independent full-bridge detection according to claim 1, wherein The output end of each full-bridge circuit is connected to the main board through a twisted pair wire.

10. The disk claw type power meter for independent full-bridge detection according to claim 1, characterized in that, The main board includes: N operational amplifier modules, an analog-to-digital conversion module and a processing chip; Wherein, each of the N full-bridge circuits is respectively connected to an operational amplifier module, and each operational amplifier module is used to amplify and filter the measurement value of the full-bridge circuit connected to it; The analog-to-digital conversion module is connected to the N operational amplifier modules and is used to perform analog-to-digital conversion of the signal to obtain N torque values; The processing chip is connected to the analog-to-digital conversion module, and is used to determine the total torque value according to N torque values and calculate the power according to the total torque value.

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