A frequency response device and measurement method for a force sensor data acquisition system

Abstract

The present invention discloses a frequency response device and measurement method for a force sensor data acquisition system, comprising a force sensor and a data acquisition system electrically connected to an output end of the force sensor. The data acquisition system is further connected to a standard source for outputting an AC standard voltage signal, a frequency meter for recording the frequency and voltage signals of the data acquisition system, and a digital multimeter through a transmission circuit. The force sensor comprises a force-sensitive elastomer and a signal output portion sleeved on the force-sensitive elastomer. A plurality of strain gauges for detecting the strain of the force-sensitive elastomer are mounted on the periphery of the force-sensitive elastomer. The plurality of strain gauges are electrically connected to the data acquisition system through signal lines on the signal output portion. A loading platform is fixed to the top of the force-sensitive elastomer. The frequency response test system can be used to more accurately obtain the frequency response of the force sensor data acquisition system, eliminating the influence factors due to the internal voltage source and maximum allowable error of the frequency response analyzer.

Description

Technical Field

[0001] The present invention relates to the technical field of force sensor measurement devices, and in particular to a device and a method for measuring the frequency response of a force sensor data acquisition system. Background Art

[0002] The force sensor's data acquisition system, connected to the force sensor's output, collects and displays the sensor's output voltage, frequency, and other signals, and evaluates the signal's amplitude, phase, and other characteristics. The data acquisition system can be used to measure both static force output signals and dynamic force evaluation. When measuring the force sensor's output signal, a crucial metric is evaluating the frequency response variation within the operating frequency range to determine whether the force sensor's dynamic and static characteristics meet requirements. According to JJG 556-2011, "Verification Procedure for Axial Force Fatigue Testing Machines," force sensor measurements must ensure that the frequency response does not vary by more than ±0.1dB within the operating frequency range. If the frequency response of the force sensor's output signal does not meet these requirements, significant measurement errors will result, making it impossible to accurately evaluate the dynamic and static force output characteristics at different frequencies.

[0003] The current calibration procedures for axial force fatigue testing machines only briefly describe the allowable variation in frequency response, but fail to describe how to measure and evaluate the frequency response. According to the measurement method for the frequency response of dynamic resistance strain gauges in JJG 623-2005, "Verification Procedures for Resistance Strain Gauges," frequency response can be measured using a frequency response meter. To measure frequency response using a frequency response meter, the output signal of a data acquisition system is connected to the meter. A reference frequency (e.g., 20 Hz) is set, the output signal's frequency is continuously varied, and the variation relative to the reference frequency is measured at each frequency point. The measurement principle involves passing the signal output from the data acquisition system through the meter's internal signal source, modulator, and dB converter, with the resulting dB value displayed on the meter.

[0004] Although the frequency response of the data acquisition system can be measured theoretically using the above method, there are many factors that affect the actual measurement process:

[0005] 1) The frequency response meter uses 1V as the output voltage standard and measures a signal of approximately 1V. The change in output voltage is measured by changing the frequency of the output voltage. However, the signal output by the force sensor to the data acquisition system is a mV signal (usually 0.1mV to 20mV). If the frequency response meter is used for measurement, the measured signal will not match the standard signal configured within it, resulting in low measurement accuracy or large measurement uncertainty.

[0006] 2) The frequency response meter has a resolution of 0.1dB and an error of ±0.1dB within the range of 10Hz to 100kHz. However, the regulations require a tolerance of ±0.1dB for the measured value, which means that the standard and the device under test must be of the same level. Therefore, the frequency response meter cannot measure the frequency response value of the force sensor data acquisition system. Summary of the Invention

[0007] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a device and a method for measuring the frequency response of a force sensor data acquisition system, so as to solve the technical problems raised in the above background technology.

[0008] The object of the present invention is achieved through the following technical solutions:

[0009] A frequency response device for a force sensor data acquisition system, comprising a force sensor and a data acquisition system electrically connected to an output terminal of the force sensor, wherein the data acquisition system is further connected via a transmission circuit to a standard source for outputting an AC standard voltage signal, a frequency meter for recording the frequency of the data acquisition system, and a digital multimeter for recording the AC voltage of the data acquisition system;

[0010] The force sensor includes a force-sensitive elastomer and a signal output part mounted on the force-sensitive elastomer. A plurality of strain gauges for detecting the strain of the force-sensitive elastomer are mounted around the force-sensitive elastomer. The plurality of strain gauges are electrically connected to the data acquisition system through signal lines on the signal output part. A loading platform is fixed on the top of the force-sensitive elastomer.

[0011] In the above invention, further, a fixing platform for fixing the force sensor is provided at the bottom of the force-sensitive elastomer, and a plurality of threaded mounting holes are provided on the fixing platform, and the force sensor is fixed to the working equipment through the threaded mounting holes and fixing bolts.

[0012] In the above invention, further, a protective shell is provided on the force-sensitive elastomer, and the protective shell includes a shell 1 fixed on the lower surface of the loading platform and a shell 2 fixed on the upper surface of the fixed platform, and the shell 1 and the shell 2 are slidably connected.

[0013] In the above invention, further, a sliding rod is fixed on the inner side of the shell one, and a sliding groove is provided on the shell two, and the sliding rod slides in the sliding groove along the length direction of the sliding groove.

[0014] In the above invention, further, the second housing is provided with a through hole for the signal line to pass through.

[0015] The above invention further includes the following steps:

[0016] S1. Connect the output end of the force sensor to the data acquisition system, which collects and displays the output voltage and frequency signals of the force sensor;

[0017] S2. Electrically connect the standard source, frequency meter, and digital multimeter. Use the standard source to output an AC standard voltage signal with an amplitude of 20mV and a frequency of 60Hz. Record the voltage displayed on the digital multimeter at this time.

[0018] S3. Without changing the signal amplitude, adjust the signal frequency to f1 and record the AC voltage display value U on the digital multimeter at this time;

[0019] S4. Calculate the frequency response of the output signal when the frequency is f1. The calculation formula is as follows:

[0020]

[0021] Where A is the frequency response of the output signal (dB);

[0022] U—actual value of voltage at other frequencies (V);

[0023] U0—actual value of voltage at reference frequency (V).

[0024] The beneficial effects of the present invention are:

[0025] By comparing and verifying different input voltages and input frequencies, the results obtained by the established frequency response test system have good consistency. Using this frequency response test system, the frequency response of the force sensor data acquisition system can be obtained more accurately, eliminating the influencing factors of the internal voltage source and maximum allowable error of the frequency response analyzer, and improving the measurement uncertainty of the frequency response of the force sensor data acquisition system. Its measurement uncertainty can be better than 0.2% (k=2). BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0027] Figure 2 Schematic diagram of the structure of the force sensor of the present invention.

[0028] In the figure, 1-force sensor, 2-data acquisition system, 3-standard source, 4-frequency meter, 5-digital multimeter, 6-force-sensitive elastic body, 7-strain gauge, 8-signal output part, 9-fixed platform, 10-loading platform, 11-protective shell, 111-shell 1, 112-shell 2. DETAILED DESCRIPTION

[0029] The following describes the embodiments of the present invention through specific examples. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments. The details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features in the embodiments can be combined with each other unless they conflict.

[0030] Example:

[0031] In the description of the present invention, it should be understood that the terms "up", "down", "left", "right", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention.

[0032] Please see the attached Figure 1 -Attached Figure 2 As shown, a frequency response device for a force sensor data acquisition system 2 includes a force sensor 1 and a data acquisition system 2 electrically connected to the output terminal of the force sensor 1. The data acquisition system 2 is used to collect and display signals such as the output voltage and frequency of the force sensor 1, and to evaluate characteristics such as the amplitude and phase of the signals. It can be used to measure both static force output signals and dynamic force evaluation. The data acquisition system 2 is also connected via a transmission circuit to a standard source 3 for outputting an AC standard voltage signal, a frequency meter 4 for recording the frequency of the data acquisition system 2, and a digital multimeter 5 for recording the AC voltage of the data acquisition system 2. The frequency meter 4 and the digital multimeter 5 can more accurately measure the adjusted frequency and voltage values.

[0033] The force sensor 1 includes a force-sensitive elastic body 6 and a signal output part 8 mounted on the force-sensitive elastic body 6. A plurality of strain gauges 7 for detecting the strain of the force-sensitive elastic body 6 are mounted around the force-sensitive elastic body 6. The plurality of strain gauges 7 are electrically connected to the data acquisition system 2 via the signal line on the signal output part 8. A loading platform 10 is fixed on the top of the force-sensitive elastic body 6. Specifically, the loading platform 10 is the force-bearing part of the force sensor 1. In order to ensure that the force sensor 1 is uniformly stressed, the loading platform 10 can be a rectangular parallelepiped or a hemispherical shape. When the hemispherical head is subjected to positive force or pressure, the force is accurately applied and has a certain protective effect on the object to which it is applied. The smooth surface will not scratch the human body or wear objects. When the loading platform 10 is subjected to external pressure, the force-sensitive elastomer 6 will be deformed. The strain gauge 7 attached to the force-sensitive elastomer 6 will sense the deformation of the force-sensitive elastomer 6 and convert the deformation of the force-sensitive elastomer 6 into a change in the resistance of the strain gauge 7. The change in resistance is then converted into a change in voltage or current through the measuring circuit. The changed signal is then output through the signal output part 8 to obtain a changed numerical value, and the pressure magnitude is obtained. The output voltage, frequency and other signals of the force sensor 1 are read, collected and displayed by the data acquisition system 2.

[0034] In the above embodiment, preferably, a fixing platform 9 for fixing the force sensor 1 is provided at the bottom of the force-sensitive elastomer 6, and a plurality of threaded mounting holes are provided on the fixing platform 9. The force sensor 1 is fixed to the working equipment through the threaded mounting holes and fixing bolts, thereby increasing the stability of the force sensor 1.

[0035] In the above embodiments, preferably, please refer to the attached Figure 2 As shown, in order to prevent the force-sensitive elastic body and strain gauge 7 from being deformed by collisions with other equipment during use, thereby affecting the accurate frequency and voltage values ​​collected by the data acquisition system 2, a protective shell 11 is provided outside the force-sensitive elastic body 6 to protect the force-sensitive elastic body 6 and strain gauge 7 from other factors and improve the accuracy of data measurement. The protective shell 11 includes a shell 111 fixed to the lower surface of the loading platform 10 and a shell 2 112 fixed to the upper surface of the fixed platform 9, and the shell 111 and the shell 2 112 are slidably connected.

[0036] In the above embodiment, preferably, a slide bar is fixed to the inner side of the first housing 111, and a slide groove is defined in the second housing 112, in which the slide bar slides along its length. Specifically, when the loading platform 10 is subjected to external pressure, the force applied to the first housing 111 causes the slide bar to move along the slide groove of the second housing 112, thereby slidingly connecting the first housing 111 and the second housing 112, and compressing the force-sensitive elastomer 6 within the protective shell 11, thereby generating deformation.

[0037] In the above embodiment, preferably, the second housing 112 is further provided with a through hole for the signal line to pass through.

[0038] The process of measuring the frequency response of the force sensor data acquisition system 2 specifically includes the following steps:

[0039] S1. First, after the force sensor 1 is fixed on the fixing platform 9, the output end of the force sensor 1 is connected to the data acquisition system 2, so that the loading platform 10 is subjected to force. The strain gauge 7 converts the deformation generated by the force-sensitive elastic body 6 into frequency and voltage signals and outputs them through the signal output unit 8. The data acquisition system 2 is used to collect and display the output voltage and frequency signals of the force sensor 1;

[0040] S2. To accurately measure the accuracy of the data from data acquisition system 2, it is also necessary to test whether the voltage signal output by data acquisition system 2 meets the requirements by measuring its frequency response. Therefore, the standard source 3, frequency meter 4, and digital multimeter 5 are electrically connected to data acquisition system 2. The standard source 3 outputs an AC standard voltage signal with an amplitude of 20mV and a frequency of 60Hz. The voltage displayed by the digital multimeter 5 at this time is recorded.

[0041] S3. Without changing the signal amplitude, adjust the signal frequency to f1 and record the AC voltage display value U of the digital multimeter 5 at this time; during the measurement, the voltage value U0 at the reference frequency and the voltage value U after the frequency adjustment can be measured by the digital multimeter 5, and the reference frequency and the adjusted frequency can be measured by the frequency meter 4.

[0042] S4. Calculate the frequency response of the output signal when the frequency is f1. The calculation formula is as follows:

[0043]

[0044] Where A is the frequency response of the output signal (dB);

[0045] U—actual value of voltage at other frequencies (V);

[0046] U0—actual value of voltage at reference frequency (V).

[0047] The above formula can be used to calculate the output frequency response value of the force sensor 1 and the data acquisition system 2. The standard instruments used in the above embodiment are relatively common in laboratories and have high accuracy. The accuracy level of the AC voltage standard is generally no greater than Class 0.1, and the accuracy level of the frequency meter 4 is no greater than Class 0.01. The entire measurement process is simple. Compared with the traditional method of measuring the data acquisition system 2 using a frequency response meter, this embodiment is easier to implement in terms of output voltage range and accuracy. The problem of large errors caused by the difference in signal units between the frequency response meter and the data acquisition system 2 is avoided.

[0048] By comparing and verifying different input voltages and input frequencies, the results obtained by the established frequency response test system have good consistency. Using this frequency response test method, the frequency response of the force sensor 1 and data acquisition system 2 can be obtained more accurately, eliminating the influencing factors of the internal voltage source and maximum allowable error of the frequency response analyzer, and improving the measurement uncertainty of the frequency response of the force sensor 1 and data acquisition system 2. The measurement uncertainty can be better than 0.2% (k=2).

[0049] This method can not only be used to measure the frequency response of the force sensor 1 and the data acquisition system 2, but also can measure the frequency response of other strain systems. If conditions permit, it can also be used to measure the frequency response of other electronic systems, and has high application value.

[0050] The above-described embodiments merely represent specific implementations of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, and all such variations and improvements fall within the scope of protection of the present invention.

Claims

1. A frequency response device for a force sensor data acquisition system, characterized in that: It includes a force sensor and a data acquisition system electrically connected to the output end of the force sensor, wherein the data acquisition system is further connected to a standard source for outputting an AC standard voltage signal, a frequency meter for recording the frequency of the data acquisition system, and a digital multimeter for recording the AC voltage of the data acquisition system through a transmission circuit. The force sensor includes a force-sensitive elastomer and a signal output part mounted on the force-sensitive elastomer. A plurality of strain gauges for detecting the strain of the force-sensitive elastomer are mounted around the force-sensitive elastomer. The plurality of strain gauges are electrically connected to the data acquisition system through signal lines on the signal output part. A loading platform is fixed on the top of the force-sensitive elastomer.

2. The frequency response device for a force sensor data acquisition system according to claim 1, characterized in that: A fixing platform for fixing the force sensor is provided at the bottom of the force-sensitive elastomer. A plurality of threaded mounting holes are provided on the fixing platform. The force sensor is fixed to the working equipment through the threaded mounting holes and fixing bolts.

3. The frequency response device for a force sensor data acquisition system according to claim 2, characterized in that: The force-sensitive elastomer is provided with a protective shell, which includes a shell 1 fixed on the lower surface of the loading platform and a shell 2 fixed on the upper surface of the fixed platform, and the shell 1 and the shell 2 are slidably connected.

4. The frequency response device for a force sensor data acquisition system according to claim 3, characterized in that: A sliding rod is fixed on the inner side of the housing 1, and a sliding groove is provided on the housing 2. The sliding rod slides in the sliding groove along the length direction of the sliding groove.

5. The frequency response device for a force sensor data acquisition system according to claim 4, characterized in that: The second shell is also provided with a through hole for the signal line to pass through.

6. A method for measuring the frequency response device of a force sensor data acquisition system according to claim 5, characterized in that: The following steps are involved: S1. Connect the output end of the force sensor to the data acquisition system, which collects and displays the output voltage and frequency signals of the force sensor; S2. Electrically connect the standard source, frequency meter, and digital multimeter to the data acquisition system. Use the standard source to output an AC standard voltage signal with an amplitude of 20 mV and a frequency of 60 Hz. Record the voltage display value U0 measured by the digital multimeter at this time. S3. Without changing the signal amplitude, adjust the signal frequency to f1 and record the AC voltage display value U on the digital multimeter at this time; S4. Calculate the frequency response of the output signal when the frequency is f1. The calculation formula is as follows: Where A is the frequency response of the output signal (dB); U—actual value of voltage at other frequencies (V); U0—actual value of voltage at reference frequency (V).

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