Wide-range high-precision steady-state and dynamic-state integrated rotating speed measuring system

Abstract

The invention discloses a wide-range high-precision steady-state and dynamic-state integrated rotating speed measuring system, and belongs to the technical field of rotating machinery metering. The system comprises a rotating speed measuring node (including an anti-interference sensor and an MCU microprocessor), an upper computer (including a time sequence coordination module and a data processing module) and a data output device, and adopts a continuous double-counting synchronous operation method to realize synchronous triggering of pulses and a time counter and period value inheritance. And a 40MHz temperature compensation crystal oscillator is matched to control the timing error within + / -1 clock period. The time sequence coordination module covers the ultra-wide range of 0.01-400000 r / min through a self-adaptive sampling mechanism (T = 0.01-25 s, K = 1-255), and the anti-interference sensor controls edge jitter within 2 microseconds. The dynamic sampling time of the system is less than or equal to 10ms, the steady-state relative error is less than or equal to 5 * 10 <-6 > (k = 2), the dynamic error is less than or equal to 1.5 * 10 <-4 >, the method is suitable for industrial automation, aero-engine testing and other scenes, the technical bottleneck is broken through, the rotating speed measurement precision and the dynamic response capability are improved, and an effective scheme is provided for precise monitoring of rotating machinery.

Description

Technical Field

[0001] The present invention belongs to the technical field of rotating machinery metrology, and specifically relates to a wide-range, high-precision, steady-state and dynamic integrated speed measurement system that combines steady-state and dynamic measurement capabilities. The system is suitable for scenarios such as industrial automation, aircraft engine testing, and ultra-precision equipment monitoring. Background Art

[0002] As a key device for rotating machinery measurement, speed meters are widely used in core industries such as industrial automation, automotive manufacturing, aerospace, and energy and electricity. Their importance is becoming increasingly prominent amidst the wave of intelligent manufacturing upgrades. For example, in industrial automation production lines, the tool speed of CNC machine tools directly affects machining accuracy and efficiency. The speed of conveying equipment in intelligent warehousing and logistics must precisely match the cargo flow rate. In engine testing in automotive manufacturing, speed measurement is fundamental to evaluating power performance and fuel economy. In the aerospace sector, engine development and aircraft attitude control rely on high-precision speed monitoring to ensure flight safety. For ultra-precision equipment such as photolithography machines and atomic force microscopes, speed accuracy determines product quality and scientific research results.

[0003] However, the current tachometers on the market have significant technical flaws, making it difficult to meet the increasingly stringent demands of various industries. The range of traditional tachometers is generally limited to 0.1 to 100,000 r / min, which cannot cover extreme operating conditions such as turbine expanders (up to 4,000,000 r / min) and air preheaters (as low as 0.01 r / min). In terms of dynamic response, the existing mainstream solutions mostly use the "segmented cumulative counting" equal-precision measurement method with a sampling interval of ≥40ms. In the face of transient processes such as engine startup and rapid acceleration, it is unable to capture rapid changes in speed, resulting in the loss of critical data. At the same time, existing technologies lack effective response strategies for the timing error amplification problem caused by sensor edge jitter (typical values ​​1 to 20 μs), making it difficult to achieve breakthroughs in measurement accuracy, and greatly restricting their application in precision manufacturing and high-end equipment.

[0004] In terms of market share, traditional mechanical tachometers still occupy a certain proportion in low- and mid-end applications where precision is not a priority due to their low cost, but their share has been declining year by year as technology has been upgraded. Digital tachometers based on MEMS technology have gradually increased their market share due to their miniaturization and digitization advantages. High-end products such as laser velocimeters have emerged in scenarios requiring high-precision and high-dynamic measurements, but their market penetration has grown slowly due to technical bottlenecks. Overall, the tachometer industry urgently needs a systematic solution that can simultaneously meet the requirements of an ultra-wide range, sub-millisecond dynamic response, and micro-error-level accuracy, in order to break the existing technological deadlock and meet the needs of high-end applications in multiple fields. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a wide-range, high-precision, steady-state, dynamic integrated speed measurement system to address the defects of the existing technology. This system breaks through the traditional range limitation and covers the full range of 0.01 to 400,000 r / min. It realizes dynamic measurement (sampling time ≤ 10 ms) through a continuous and uninterrupted double-counting synchronous operation method, and suppresses the sensor edge jitter error, making the system relative error ≤ 5×10 -6 (k=2).

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] A wide-range, high-precision, steady-state, and dynamic integrated speed measurement system includes a speed measurement node, a host computer, and a data output device. Data exchange between the speed measurement node and the host computer, and between the host computer and the data output device, is performed via wired or wireless communication.

[0008] The speed measurement node includes several anti-interference speed sensors, each of which has a built-in MCU microprocessor. The MCU microprocessor has a built-in synchronously triggered pulse counter and time counter. The speed physical quantity of the rotating part is obtained through a continuous and uninterrupted double-counting synchronous operation method and converted into an electrical signal or a pulse signal.

[0009] The host computer includes:

[0010] The timing coordination module is used to dynamically adjust the sampling period T and the extension multiple K to generate a coordinated timing chain between the MCU microprocessor and the host computer;

[0011] The data processing module processes the speed physical quantity based on the continuous and uninterrupted double counting synchronous operation algorithm, processes the speed physical quantity, calculates the speed and calibrates the sensor edge jitter error;

[0012] Data output device supports digital display, chart recording (such as dynamic process curves) and wired / wireless data export.

[0013] As a further description of the above technical solution, the continuous uninterrupted double counting synchronization algorithm includes:

[0014] The pulse counter is triggered synchronously with the time counter;

[0015] The end value of a period is automatically inherited as the initial value of the next period (zero count truncation error);

[0016] The timing error is ±1 clock cycle, and the clock frequency is ≥40MHz (typical value 0.3μs@40MHz temperature-compensated crystal oscillator).

[0017] As a further description of the above technical solution, the timing coordination module adopts an adaptive sampling mechanism to automatically adjust the sampling time T and the extension multiple K according to different application fields. The minimum speed calculation formula is 60 / (T×K)r / min, where the sampling period T ranges from 0.01 to 25s and the extension multiple K ranges from 1 to 255;

[0018] The dynamic sampling time T can be set within 0.01 to 0.5s, and the extension multiple K can be set within the range of 1 to 255;

[0019] The steady-state sampling time T can be set within 0.5 to 2.5 seconds, and the extension multiple K can be set within the range of 1 to 255;

[0020] The ultra-low-speed steady-state sampling time T can be set within 1 to 25 seconds, and the extension multiple K can be set within the range of 1 to 255;

[0021] The formula for calculating the minimum speed is: 60 / (T×K). For example, when T=25s and K=255, the minimum speed is ≈0.01r / min.

[0022] As a further description of the above technical solution, the MCU microprocessor adopts a 32-bit processor, integrates 16-bit hardware capture and 16-bit software expansion, is equipped with a 40MHz temperature-compensated crystal oscillator, has a communication baud rate of 115200bps, and has dynamic and steady-state speed measurement functions:

[0023] When the speed source has its own inherent error, the speed measurement system can reproduce its error;

[0024] When the speed source causes measurement error due to vibration, the error can be reduced by increasing the number of averaging points;

[0025] When the error is caused by the limited jitter of the speed sensor edge, the speed measurement system can weaken its influence by increasing the sampling time and reproduce the error of the speed source.

[0026] As a further description of the above technical solution, the collaborative timing chain between the MCU microprocessor and the host computer satisfies: sampling time t_sam<10ms, calculation time t_cal<2ms, communication time t_com<1.5ms, and data processing time t_dp<4ms.

[0027] As a further description of the above technical solution, the anti-interference speed sensor is powered by a lithium battery and has the ability to resist power supply disturbances; its MCU microprocessor and the sensing part are integrated on the same circuit board to avoid the additional jitter caused by the distributed capacitance on the transmission line to the signal edge; the signal transmission adopts an optoelectronic isolation design.

[0028] As a further description of the above technical solution, the anti-interference speed sensor includes a laser speed sensor or a Hall speed sensor:

[0029] The laser speed sensor adopts 500kHz modulated laser emission and monostable demodulation circuit with edge jitter ≤ 2μs. The 500kHz modulated laser emission and monostable demodulation circuit are used to meet the existing accuracy requirements and dynamic characteristics requirements. If higher accuracy requirements or dynamic characteristics indicators are required, the principles and methods of 1MHz (or higher) frequency modulated laser emission and monostable demodulation circuit are also applicable.

[0030] The Hall speed sensor uses a Hall sensor chip with a built-in chopper amplifier, and the edge jitter is ≤1μs.

[0031] As a further description of the above technical solution, the parameters of the monostable demodulation circuit of the laser speed sensor meet the following requirements:

[0032] Resistance R∈1.8~2.2kΩ, capacitance C∈2000~3300pF, pulse width tw=0.55×R×C>2μs.

[0033] As a further description of the above technical solution, the data processing module supports steady-state and dynamic measurement modes: the sampling period of steady-state measurement is T≥1s; the sampling period of dynamic measurement is T=10ms.

[0034] The principle of the continuous and uninterrupted pulse time synchronization counting algorithm of the present invention is: the rising edge of the measured speed pulse signal serves as the capture trigger of the pulse counter, and the initial values ​​n_start and t_start are recorded at the same time; after the sampling period is reached, wait for the next rising edge trigger and record the end values ​​n_end and t_end. The actual sampling time t = t_end-t_start, the pulse count value n = n_end-n_start, the pulse frequency f = n / t, and the speed (r / min) = 60×f / p (p is the number of pulses per revolution). The end value is automatically inherited as the initial value of the next cycle. The pulse counting error of this method is zero, and the error comes from the timing error ±1 timing cycle. The relative error of frequency measurement ε≤1 / (T0×timing frequency).

[0035] Speed ​​measurement requires consideration of the influence of sensor edge jitter, Δt. Speed ​​measurement uses a speed sensor to convert speed into an electrical signal frequency, and sensor edge jitter, Δt, significantly impacts error. When the timing pulse period is 0.5μs, the proposed sampling period is 1s, and the edge jitter, Δt, is 20μs, the error rate, ε, is ≤ (1+Δt) / (T0 × timing frequency). Therefore, reducing edge jitter and increasing the timing frequency can significantly improve measurement accuracy.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] 1. The present invention adopts a continuous and uninterrupted dual-count synchronous operation method to measure the rotational speed, which ensures the ability of higher-precision measurement during high-speed sampling, and also ensures that there will be no intermittent discontinuity caused by counting truncation during the dynamic measurement process.

[0038] 2. This invention has made a qualitative improvement in steady-state performance by fully analyzing the source of speed measurement error and taking targeted improvement measures. The sampling time is advanced to 10ms (minimum sampling time is 6ms), which can capture a step change of 0.01r / min, and the steady-state relative error is ≤5×10 -6 (k=2); dynamic error ≤1.5×10-4 (10ms sampling), the accuracy level of dynamic measurement is better than 0.02%, and the dynamic measurement of rotation speed has wider practicality.

[0039] 3. Achieve a speed measurement range of 0.01 to 400,000 r / min (400 times larger than traditional equipment) and a frequency measurement range of 0.0016 to 30,000 Hz, achieving full coverage of the measurement range. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is the architecture diagram of a wide-range, high-precision, steady-state, and dynamic integrated speed measurement system.

[0041] Figure 2 This is the principle block diagram of the laser speed sensor.

[0042] Figure 3 This is the principle block diagram of the Hall speed sensor.

[0043] Figure 4 It is the circuit diagram of the modulation transmission circuit.

[0044] Figure 5 This is the circuit diagram of the demodulation circuit.

[0045] Figure 6 It is the modulation waveform and the demodulated waveform.

[0046] Figure 7 It is the MCU microprocessor-host computer collaborative timing diagram.

[0047] Figure 8 It is the principle diagram of the continuous and uninterrupted pulse time synchronous counting operation algorithm.

[0048] Figure 9 This is a diagram of the digital display window and steady-state recording window under high-speed measurement.

[0049] Figure 10 This is a diagram of the digital display window and steady-state recording window under ultra-low speed measurement.

[0050] Figure 11 It is a dynamic process curve diagram under ultra-low speed measurement.

[0051] Figure 12 It is a record of tiny jumps.

[0052] Figure 13 It is the steady-state window and dynamic curve diagram of low-speed measurement. DETAILED DESCRIPTION

[0053] The specific technical contents of the present invention are further described in detail below through examples, but this should not be understood as the scope of the above subject matter of the present invention being limited to the following examples. All technologies implemented based on the above contents of the present invention belong to the scope of the present invention.

[0054] Example 1

[0055] The wide-range, high-precision, steady-state, and dynamic integrated speed measurement system of the present invention can be used to calibrate various speed standard devices and to measure various rotating mechanical equipment. In different industrial sites, different speed sensors can be adapted due to different working conditions, such as magnetoelectric speed sensors, photoelectric speed sensors, laser speed sensors, and vibration sensors. The system architecture is as follows: Figure 1 Shown, including:

[0056] Speed ​​measurement node, host computer and data output device: The speed measurement node is connected to the host computer via wireless communication (Bluetooth, WiFi), eliminating the inconvenience caused by wiring in laboratories and industrial sites. At the same time, it also retains wired transmission solutions, such as matching with magnetoelectric speed sensors for dynamic speed measurement of aircraft engines. Data exchange between the host computer and the data output device is carried out through wired connection (or wireless communication).

[0057] The speed measurement node includes four anti-interference speed sensors, each of which has a built-in MCU microprocessor. The MCU microprocessor has a built-in synchronously triggered pulse counter and time counter for obtaining the speed physical quantity of the rotating component (including pulse and time counting data, etc.) and converting it into a pulse signal or electrical signal;

[0058] The host computer includes:

[0059] The timing coordination module is used to control the adaptive adjustment of the sampling period and the extension multiple, and generate a coordinated timing chain between the MCU microprocessor and the host computer;

[0060] The data processing module processes the speed physical quantity (pulse / time count data) based on a continuous and uninterrupted dual-count synchronous operation algorithm, calculates the speed (r / min) and calibrates the edge jitter error. This not only ensures higher-precision measurement capabilities during high-speed sampling, but also prevents intermittent discontinuities caused by count truncation during dynamic measurement.

[0061] Data output module supports digital display, chart recording (such as dynamic process curves) and wired / wireless data export.

[0062] The anti-interference speed sensor is powered by a lithium battery and has the ability to resist power supply disturbances; the MCU microprocessor and the sensing part are integrated on the same circuit board to avoid additional jitter caused by the distributed capacitance on the transmission line on the signal edge; the signal transmission adopts a photoelectric isolation design.

[0063] The following uses the laser speed sensor and the Hall speed sensor as examples to illustrate:

[0064] The laser speed sensor uses modulated light and receiving demodulation as the laser sensing part. The modulated light is emitted by a 500kHz modulated laser and is received and demodulated as the frequency measurement signal of the MCU microprocessor. Figure 2 As shown, compared with ordinary laser sensors, this signal has stronger resistance to light interference, and the signal rising edge jitter can be controlled within 2μs. Therefore, it uses a lithium battery to power the sensor, avoiding disturbances caused by grid voltage fluctuations. The sensing part and the MCU microprocessor are located on the same circuit board to avoid additional jitter caused by distributed capacitance on the transmission line.

[0065] The Hall sensor part of the Hall speed sensor senses the speed signal through optical isolation and transmits it to the MCU microprocessor, which has strong electromagnetic interference resistance. The Hall chip selected for this Hall sensor part has a built-in chopper amplifier and strong resistance to low-frequency magnetic interference. The signal edge jitter can be controlled within 1μs in the full frequency range of 0~25kHz. Figure 3 As shown in the figure, the lithium battery-powered sensor avoids disturbances from grid voltage fluctuations. The sensor and MCU are located on the same circuit board, eliminating the additional jitter caused by distributed capacitance on the transmission line.

[0066] The laser speed sensor uses the time base frequency division output of the MCU microprocessor to add a transistor to drive the laser diode LD to generate a 500kHz carrier laser emission for frequency modulation, such as Figure 4 As shown. Demodulation is performed using a monostable circuit consisting of two AND gates, a resistor R, and a capacitor C, as shown Figure 5As shown in the figure, Fin is the intermittent modulation waveform of the modulation signal received by the laser speed sensor after amplification and shaping; Fout is the output signal after demodulation by the monostable circuit:

[0067] When Fin is 0, the output of the first AND gate is 0, and the output of the second AND gate is also 0, which is the steady state;

[0068] When Fin has a rising edge (changes from 0 to 1), the output of the first AND gate is 1, and the output of the second AND gate is also 1. This is a transient state;

[0069] As time goes by, the capacitor C is charged to a certain time tw, the voltage on the resistor R is lower than the threshold, and the output of the second AND gate will become 0; if Fin has a rising edge before reaching the threshold, the output of the second AND gate will remain 1, so a continuous string of modulated pulses can maintain a high level, and the end of a string of pulses will produce a low level, and the intermittent pulse string is demodulated and restored to the corresponding speed pulse, such as Figure 6 shown.

[0070] The monostable circuit inputs a pulse signal, and the rising edge of the pulse signal triggers the generation of a fixed pulse width pulse. When the pulse width is greater than the period of the modulation signal, the continuous modulation pulses in the intermittent modulation pulses become a continuous high level at the output end until the induced modulation pulse is disconnected and the output end becomes a low level.

[0071] The delay of the td gate circuit is about 10ns (which can be ignored in practice).

[0072] Derivation of the theoretical values ​​of the monostable circuit resistance R and capacitance C:

[0073] tw=k×R×C;

[0074] The unit of tw is ns, the unit of R is kΩ, and the unit of C is pF;

[0075] k = 0.55, VCC = 5.0V;

[0076] tw>modulation frequency period;

[0077] Taking the modulation frequency of 500kHz as an example, the pulse width of the monostable pulse must be greater than 2μs, and the capacitor C is selected from 2000~3300pF. Then tw=2μs=2000ns=0.55×R×2000, and R=2000 / 1100=1.818kΩ is derived. The actual value is 1.8~2.2kΩ.

[0078] The timing coordination module uses an adaptive sampling mechanism to automatically adjust the sampling time T and extension multiple K according to different application fields:

[0079] The dynamic sampling time T can be set in the range of 0.01 to 0.5s, and the extension multiple K can be set in the range of 1 to 255;

[0080] The steady-state sampling time T can be set in the range of 0.5 to 2.5 seconds, and the extension multiple K can be set in the range of 1 to 255;

[0081] The ultra-low-speed steady-state sampling time T can be set in the range of 1 to 25s, and the extension multiple K can be set in the range of 1 to 255;

[0082] The formula for calculating the minimum speed is 60 / (T×K)r / min: If the sampling time is set to 0.01s and the extension multiple is 5, the sampling time during measurement will automatically adapt to the measurement needs between 0.01s×(1~5) according to the change of frequency, and the minimum speed is: 60 / (0.01×5)=1200r / min; if the sampling time is set to 25s and the extension multiple is 225, the sampling time during measurement will automatically adapt to the measurement needs between 25s×(1~255) according to the change of frequency, and the minimum speed is: 60 / (25×255)≈0.009412=0.01r / min.

[0083] In order to achieve the purpose of dynamic acquisition, the timing of the MCU microprocessor in sampling, calculation, communication and other links must be coordinated and connected with the timing of the host computer. The timing planning is as follows: Figure 7 As shown:

[0084] The actual sampling time is t_sam, the calculation time after capture is t_cal, the communication time between the MCU and the host computer is t_com, and the data processing and recording time of the host computer is t_dp. All timings are properly coordinated and connected to ensure that the calculations and communications performed by the MCU after the first capture, as well as the data processing by the host computer, are completed before the next capture, and that the second sampling by the MCU runs in parallel with the previous calculation without interruption or error.

[0085] The actual sampling time t_sam<10ms, and t_cal+t_com+t_dp <t_sam。

[0086] To meet the above timing requirements, a 32-bit MCU microprocessor, a 40MHz temperature-compensated crystal oscillator, a communication baud rate of 115200bps, and an Intel(R) Core(TM) i7-8650U CPU @ 1.90GHz are used as the host computer chip. The specific timing plan is as follows:

[0087] The actual sampling time target is <10ms, the calculation time t_cal <2ms, the communication time t_com <1.5ms (baud rate 115200bps), and the data processing time t_dp <4ms. Therefore, t_cal + t_com + t_dp <2 + 1.5 + 4 = 7.5ms.

[0088] The host computer is optimized to change recording and display to parallel processing, shortening the time to 2.5ms, and the actual sampling time can reach 6ms.

[0089] As the configuration of the host computer is improved, the data processing and recording time t_dp of the host computer will be further shortened.

[0090] The MCU microprocessor uses a 32-bit single-chip microprocessor, and its capture part is 32 bits consisting of 16-bit hardware + 16-bit software. If 32-bit hardware capture is used, the operation time of the MCU microprocessor will be further shortened. In view of the balance between cost and goals, the target of dynamic measurement of the present invention is 10ms sampling time, and the dynamic error is better than 0.02%. Using a domestic 32-bit microprocessor, 16-bit hardware of the capture part is sufficient.

[0091] The principle of the continuous uninterrupted pulse / time synchronization counting algorithm of the present invention is as follows Figure 8 As shown, the rising edge of the measured speed pulse signal serves as the capture trigger of the pulse counter, and the measured pulse count initial value n_start and the time count initial value t_start are captured and recorded at the same time. When the planned sampling period T0 arrives, the next rising edge of the measured pulse is waited for to trigger the capture, and the measured pulse count end value n_end of this period and the time count end value t_end of this period are captured. The actual sampling time of this period t = t_end - t_start (such as t1, t2...); the pulse count value n of this period = n_end - n_start, (such as n1, n2...). The pulse frequency f of this period = n / t, and the speed (r / min) = pulse frequency f × 60 / number of pulses per revolution (p), that is, speed = 60f / p.

[0092] The pulse count end value of one cycle automatically becomes the initial value of the pulse count of the next cycle. The end value of the time count of one cycle also becomes the initial value of the time count of the next cycle, and this cycle continues uninterrupted. Throughout the measurement process, the MCU microprocessor's measured pulse counter has zero error, the time counter has an error of ±1 timing cycle in one measurement cycle, and the long-term time count has an error of only ±1 count pulse.

[0093] The advantages of the continuous uninterrupted pulse / time synchronous counting algorithm include high measurement accuracy. The pulse counting error is zero, and the error comes from the timing error ±1 timing cycle. The actual sampling period t ≥ the proposed sampling period T0 is always true, so the relative frequency measurement error ε ≤ 1 / (T0 × timing frequency). As shown in Table 1, the theoretical upper limit of the system frequency measurement relative error under different timing frequencies and proposed sampling times is shown in the table: when the sampling time T0 = 1s, the error of the 24MHz / 12 timing frequency is ≤ 1×10 -6 , and the error of the 40MHz / 12 timing frequency is further reduced to ≤3×10-7, and the accuracy is improved by about 3 times; when T0 is shortened to 10ms, the error increases significantly (for example, the error of the 24MHz / 12 timing frequency is ≤1×10 -4 ), indicating that short sampling time will reduce measurement accuracy.

[0094] Table 1 Relationship between timing frequency and relative error ε

[0095]

[0096] The present invention can control the error to a micro-error level (≤5×10 -6 ) to meet high-precision requirements. During dynamic measurement (T0 = 10ms), by optimizing sensor edge jitter (e.g., ≤ 1μs) and algorithm compensation, the error is further reduced to ≤ 1.5×10 -4 , breaking through the limitations of traditional technology.

[0097] Speed ​​measurement differs from frequency measurement. The speed signal is sensed by a speed sensor, which converts the speed into the frequency of an electrical signal. This results in a combination of errors caused by the speed sensor during the conversion and transmission process. The rising and falling edge jitter of the frequency generated by the speed sensor when sensing a rotating object is particularly pronounced in speed measurement errors. Improving the measurement accuracy of a speed sensor, after ensuring high precision in the measurement principle, is crucial to reducing errors in the speed sensor signal and signal transmission.

[0098] The following combination Figure 8 The schematic diagram shown is explained:

[0099] If the rising / falling edge delta t of the speed sensor is fixed, the rising / falling edge times at the beginning and end of the sampling period will cancel each other out during the timing count, without affecting the measurement error. However, in reality, the two values ​​are not equal and cannot be offset. Δt is the limit of the difference. The resulting error is non-negligible.

[0100] Due to the rising / falling edge jitter, the count value of the time pulse has an error of Δt when measuring the rotational speed.

[0101] For example, when the timing pulse period is 0.5μs and the proposed sampling period is 1s, assuming Δt is 20μs and the sampling time is 1s, the error rate is f = n / (t′±1). Because the relative computational error ε caused by rising edge jitter and timing is ≤ (1+Δt) / (T0×timing frequency), the results are shown in Tables 2 and 3. It can be seen that reducing edge jitter significantly improves speed measurement accuracy, and increasing the timing frequency also significantly improves it. Therefore, measurement accuracy can be improved by reducing edge jitter and increasing the timing frequency.

[0102] Table 2 Relative error when edge jitter Δt is 10μs

[0103]

[0104] Table 3 Relative error when edge jitter Δt is 2μs

[0105]

[0106] Generally speaking, the jitter of the pulse signal edge is not only caused by the instability of the speed source itself, but also by the instability of the sensor. The following describes the differences between several types of instability.

[0107] The main reasons for rising / falling edge jitter are as follows:

[0108] The speed of rotating machinery is not stable enough;

[0109] The rising / falling edge jitter of the speed sensor (the impact of this on the measured value can be reduced by increasing the sampling time);

[0110] There is relative movement or vibration between the axis of the machine being measured and the speed sensor (this can be overcome by changing the installation position and installation method of the speed sensor).

[0111] The rising / falling edge of the sensor is one of the performance characteristics of the speed sensor, which can be known in advance. For example, the pulse edge jitter Δt of the Hall speed sensor is about 1μs, and some can reach 400ns. Therefore, the error of the Hall speed sensor and the calculation error is less than 1×10 -7 The speed frequency measurement system is matched, and the speed measurement relative error can be predicted, as shown in Table 4.

[0112] Table 4 Relative error of Hall effect sensor when edge jitter Δt is 1μs

[0113]

[0114]

[0115] Using 32-bit MCU microprocessor for dynamic measurement, when the edge jitter is ≤1μs, the relative error is less than 6×10 -5 ,Compared with traditional equipment, the accuracy level and dynamic performance are improved, as shown in Table 5.

[0116] Table 5 Comparison of accuracy level and dynamic performance with traditional equipment

[0117]

[0118] By thoroughly analyzing the sources of speed measurement errors and implementing targeted improvement measures, this invention has achieved a substantial improvement in steady-state performance. The sampling time has been increased to 10ms, and the accuracy of dynamic measurement has improved to better than 0.02%, making dynamic speed measurement more widely applicable. The measurement speed range has been expanded to 0.01 to 400,000 rpm, and the measurement frequency range has been expanded to 0.0016 to 30,000 Hz.

[0119] Example 2

[0120] The following actual measurement uses the SMU-23 high-precision, wide-range speed generator (a speed standard device jointly developed by the China National Institute of Metrology and Shanghai Qingke Instrument Electronics Co., Ltd.) as the speed source:

[0121] 1. High-speed measurement:

[0122] There are 60 light-transmitting teeth on the signal plate as reflection points. 6666.6666 r / min simulates 400000 r / min. Its digital display window and steady-state record are as follows: Figure 9 shown.

[0123] 2. Ultra-low speed measurement:

[0124] The magnetic sensor is aimed at the 60-tooth signal transmission gear, measuring 0.01r / min, the measurement module coefficient is set to 1.0, the sampling time is set to 2.40s, the extension multiple is set to 101, and the number of average points is set to 6. The digital display window and steady-state record are as follows Figure 10 shown.

[0125] 3. Dynamic process recording:

[0126] The program is: start → 3000r / min → 1000r / min → 2000r / min → 500r / min → 3000r / min →, and its dynamic process curve is as follows Figure 11 (A) shown.

[0127] 3000r / min→1000r / min→2000r / min→500r / min→3000r / min→stop, its dynamic process curve is as follows Figure 11 (B) shown.

[0128] 4. Recording of small jumps:

[0129] The dynamic curve of the jump from 2000r / min to 2000.01r / min to 1999.99r / min to 2000r / min is as follows: Figure 12 (A) shown.

[0130] The dynamic curve of 3000.01r / min→3000r / min→2999.99r / min→3000r / min3000.01 r / min→2999.99r / min jump is as follows Figure 12 (B) shown.

[0131] 5. Low-speed measurement:

[0132] The steady-state window of 1 r / min is as follows Figure 13 (A) shows the dynamic curve. Figure 13 (B) shown.

[0133] 6. System calibration and accuracy assessment:

[0134] Using a conventional standard speed generator to match a laser speed sensor or a Hall speed sensor, the uncertainty Urel (k = 3) is better than 5×10 -5 , Urel (k = 3) is better than 2×10 -5 .

[0135] Using a high-precision wide-range standard speed generator to match a laser speed sensor or a Hall speed sensor, Urel (k = 3) is better than 1×10 -5 , Urel (k = 3) is better than 5×10 -6 .

[0136] By increasing the number of reflective markers (10 fan-shaped windows) and simulating a 10-fold speed, the Urel (k = 3) at 0.1 to 15000 r / min was still better than 3×10 -6 .

[0137] Under the verification conditions of the standard speed generator, the Urel reproduced by the speed sensor is the result of the combined superposition of the Urel of the device itself, the Urel of the sensor, and the Urel caused by other factors. -6(k=2), it can be determined that the Urel of the sensor and the speed standard generator are better than 3×10 -6 According to conservative estimation, the measurement accuracy of the system of the present invention can reach 5×10 -6 (k=2), meeting industrial-grade high-precision requirements.

[0138] The above embodiments describe the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for illustrating the principles of the present invention. Without departing from the scope of the principles of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of protection of the present invention.

Claims

1. A wide-range, high-precision, steady-state, and dynamic integrated speed measurement system, including a speed measurement node, a host computer, and a data output device. Data exchange between the speed measurement node and the host computer, and between the host computer and the data output device, is achieved through wired or wireless communication. Its characteristics are: The speed measurement node includes several anti-interference speed sensors, each of which has a built-in MCU. Microprocessor, MCU microprocessor built-in synchronous trigger pulse counter and time counter, through continuous uninterrupted The dual-count synchronous operation method obtains the physical quantity of the rotating part's speed and converts it into an electrical signal or pulse signal; The host computer includes: The timing coordination module is used to dynamically adjust the sampling period T and the extension multiple K, and generate the timing coordination module between the MCU microprocessor and the upper Cooperative timing chain of bit machines; The data processing module processes the speed physical quantity based on the continuous and uninterrupted double counting synchronous operation algorithm, processes the speed physical quantity, calculates the speed and calibrates the sensor edge jitter error; The data output device supports digital display, chart recording and wired / wireless data export.

2. The system according to claim 1, wherein: The continuous and uninterrupted double counting synchronous operation method includes: The pulse counter is triggered synchronously with the time counter; The end value of a period is automatically inherited as the initial value of the next period; The timing error is ±1 clock cycle, and the clock frequency is ≥40MHz.

3. The system according to claim 1, wherein: The timing coordination module adopts an adaptive sampling mechanism to automatically adjust the sampling time T and the extension multiple K according to different application fields. The minimum speed calculation formula is 60 / (T×K)r / min, where the sampling period T ranges from 0.01 to 25s and the extension multiple K ranges from 1 to 255.

4. The system according to claim 1, wherein: The MCU microprocessor adopts a 32-bit processor, integrates 16-bit hardware capture and 16-bit software expansion, is equipped with a 40MHz temperature-compensated crystal oscillator, and has a communication baud rate of 115200bps.

5. The system according to claim 4, characterized in that The collaborative timing chain between the MCU microprocessor and the host computer meets the following requirements: sampling time t_sam<10ms, calculation time t_cal<2ms, communication time t_com<1.5ms, and data processing time t_dp<4ms.

6. The system according to claim 1, wherein: The anti-interference rotation speed sensor is powered by a lithium battery, and its MCU microprocessor and sensor part are integrated on the same circuit board, and the signal transmission adopts a photoelectric isolation design.

7. The system according to claim 6, characterized in that The anti-interference speed sensor includes a laser speed sensor or a Hall speed sensor: The laser speed sensor uses 500kHz modulated laser emission and a monostable demodulation circuit, with an edge jitter of ≤2μs; The Hall speed sensor adopts a Hall sensor chip with a built-in chopper amplifier and a photoelectric isolation circuit, and the edge jitter is ≤1μs.

8. The system according to claim 7, characterized in that The monostable demodulation circuit parameters of the laser rotation speed sensor meet the following requirements: resistance R∈1.8-2.2 kΩ, capacitance C∈2000-3300 pF, and pulse width tw=0.55×R×C>2 μs.

9. The system according to claim 1, wherein: The data processing module supports steady-state and dynamic measurement modes: the sampling period of steady-state measurement is T≥1s; the sampling period of dynamic measurement is T=10ms.

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