Method, device and system for measuring friction torque of liquid metal ball bearing

Abstract

The application relates to the technical field of friction torque measurement, and particularly discloses a friction torque measurement method, device and system for a liquid metal ball tube bearing, which comprises the following steps: obtaining a measurement signal of an acceleration sensor; performing filter pretreatment on the measurement signal of the acceleration sensor to obtain a measurement pretreatment signal of the acceleration sensor; performing time domain to frequency domain processing on the measurement pretreatment signal of the acceleration sensor to obtain an instantaneous rotating speed of the liquid metal ball tube bearing; determining a preliminary measurement result of the friction torque of the liquid metal ball tube bearing according to the instantaneous rotating speed of the liquid metal ball tube bearing; and performing data fusion processing on the static friction torque signal and the preliminary measurement result of the friction torque of the liquid metal ball tube bearing to obtain an actual measurement result of the friction torque of the liquid metal ball tube bearing. The friction torque measurement method for the liquid metal ball tube bearing provided by the application can realize the friction torque measurement of the liquid metal ball tube bearing in the non-transparent metal cover and the vacuum environment.

Description

Technical Field

[0001] The present invention relates to the technical field of friction torque measurement, and in particular to a friction torque measurement method for a liquid metal spherical tube bearing, a friction torque measurement device for a liquid metal spherical tube bearing, and a friction torque measurement system for a liquid metal spherical tube bearing. Background Art

[0002] Traditional friction torque measurement methods require a torque sensor connected between the rotor and the load via a coupling. This method is considered dynamic torque measurement. Because the bearings of the liquid metal tube are enclosed within a sealed, vacuum-protected metal housing, traditional torque meters cannot be installed for measurement. Conventional photoelectric sensors are also inoperable due to the opacity of metal. Furthermore, while static torque sensors have been used to directly measure the friction torque of liquid metal tube bearings, their accuracy and stability are limited.

[0003] Therefore, how to provide a friction torque measurement method for a liquid metal spherical tube bearing in an opaque metal cover and a vacuum environment has become a technical problem that needs to be solved urgently by those skilled in the art. Summary of the Invention

[0004] The present invention provides a method for measuring the friction torque of a liquid metal spherical tube bearing, a device for measuring the friction torque of a liquid metal spherical tube bearing, and a system for measuring the friction torque of a liquid metal spherical tube bearing, which solve the problem in the related art that it is impossible to measure the friction torque of a liquid metal spherical tube bearing in a vacuum environment within an opaque metal cover.

[0005] As a first aspect of the present invention, a method for measuring the friction torque of a liquid metal ball tube bearing is provided, wherein an acceleration sensor is provided on the outer surface of a metal cover of the liquid metal ball tube, and a target plate and a bearing are provided within the metal cover of the liquid metal ball tube in a vacuum environment. The method for measuring the friction torque of the liquid metal ball tube bearing comprises:

[0006] acquiring a measurement signal from the acceleration sensor when the rotation speed of the target disk reaches a preset rotation speed threshold, wherein the liquid metal bulb is capable of stopping the output of the anode driver when the rotation speed of the target disk reaches the preset rotation speed threshold;

[0007] Performing filtering preprocessing on the measurement signal of the acceleration sensor to obtain a measurement preprocessing signal of the acceleration sensor;

[0008] Performing time-domain to frequency-domain processing on the measurement preprocessing signal of the acceleration sensor to obtain the instantaneous rotation speed of the liquid metal ball tube bearing;

[0009] determining a preliminary measurement result of the friction torque of the liquid metal spherical tube bearing according to the instantaneous rotational speed of the liquid metal spherical tube bearing;

[0010] A static friction torque signal of the liquid metal spherical tube bearing is obtained, and data fusion processing is performed based on the static friction torque signal and the preliminary measurement result of the friction torque of the liquid metal spherical tube bearing to obtain an actual measurement result of the friction torque of the liquid metal spherical tube bearing.

[0011] Furthermore, filtering and preprocessing the measurement signal of the acceleration sensor to obtain the measurement preprocessed signal of the acceleration sensor includes:

[0012] Performing preliminary filtering processing on the measurement signal of the acceleration sensor to filter out high-frequency interference signals and obtain a preliminary filtering result of the acceleration sensor;

[0013] A smoothing attenuation process is performed on the preliminary filtering result of the acceleration sensor to obtain a measurement preprocessing signal of the acceleration sensor.

[0014] Furthermore, the instantaneous rotational speed of the liquid metal ball tube bearing is obtained after performing time-domain to frequency-domain processing on the measurement preprocessing signal of the acceleration sensor, including:

[0015] Performing short-time Fourier transform on the measurement preprocessing signal of the acceleration sensor to convert the measurement preprocessing signal of the acceleration sensor in the time domain into the measurement preprocessing signal of the acceleration sensor in the frequency domain;

[0016] The instantaneous rotational speed of the liquid metal ball tube bearing is obtained according to the measurement preprocessing signal of the acceleration sensor in the frequency domain.

[0017] Furthermore, determining a preliminary measurement result of the friction torque of the liquid metal ball tube bearing according to the instantaneous rotational speed of the liquid metal ball tube bearing includes:

[0018] determining the angular acceleration of the liquid metal spherical tube bearing according to the instantaneous rotational speed of the liquid metal spherical tube bearing;

[0019] A preliminary measurement result of the friction torque of the liquid metal spherical tube bearing is determined according to the angular acceleration of the liquid metal spherical tube bearing and in combination with the moment of inertia of the liquid metal spherical tube bearing.

[0020] Furthermore, determining the angular acceleration of the liquid metal ball tube bearing according to the instantaneous rotational speed of the liquid metal ball tube bearing comprises:

[0021] Determining the instantaneous speed difference according to two adjacent instantaneous speeds of the liquid metal ball tube bearing;

[0022] Converting the instantaneous rotational speed difference into an angular velocity difference;

[0023] The angular acceleration of the liquid metal ball tube bearing is determined according to the angular velocity difference.

[0024] Furthermore, a static friction torque signal of the liquid metal spherical tube bearing is obtained, and data fusion processing is performed based on the static friction torque signal and the preliminary measurement result of the friction torque of the liquid metal spherical tube bearing to obtain an actual measurement result of the friction torque of the liquid metal spherical tube bearing, including:

[0025] collecting a static friction torque signal of a static torque sensor mounted on the liquid metal ball tube bearing;

[0026] Cross-validating the static friction torque signal and the preliminary friction torque measurement result to obtain the static friction torque signal and the preliminary friction torque measurement result after removing abnormal values;

[0027] The static friction torque signal after removing abnormal values ​​and the preliminary measurement result of friction torque are weightedly fused in a weighted fusion manner to obtain the actual measurement result of friction torque of the liquid metal ball tube bearing.

[0028] Furthermore, it also includes:

[0029] The actual measurement result of the friction torque of the liquid metal ball tube bearing is sent to a host computer, so that the host computer generates visualization information of the friction torque of the liquid metal ball tube bearing according to the actual measurement result of the friction torque of the liquid metal ball tube bearing.

[0030] As another aspect of the present invention, a device for measuring the friction torque of a liquid metal ball tube bearing is provided, which is used to implement the method for measuring the friction torque of a liquid metal ball tube bearing described above. An acceleration sensor is provided on the outer surface of a metal cover of the liquid metal ball tube, and a target plate is provided in a vacuum environment within the metal cover of the liquid metal ball tube. The device for measuring the friction torque of the liquid metal ball tube bearing comprises:

[0031] an acquisition module, configured to acquire a measurement signal from the acceleration sensor when the rotation speed of the target disk reaches a preset rotation speed threshold, wherein the liquid metal bulb is capable of stopping the output of the anode driver when the rotation speed of the target disk reaches the preset rotation speed threshold;

[0032] A preprocessing module, configured to perform filtering preprocessing on the measurement signal of the acceleration sensor to obtain a measurement preprocessing signal of the acceleration sensor;

[0033] A conversion module, configured to perform time-domain to frequency-domain processing on the measurement preprocessing signal of the acceleration sensor to obtain the instantaneous rotational speed of the liquid metal ball tube bearing;

[0034] a preliminary result determination module, configured to determine a preliminary measurement result of the friction torque of the liquid metal spherical tube bearing according to the instantaneous rotational speed of the liquid metal spherical tube bearing;

[0035] The actual result acquisition module is used to obtain the static friction torque signal of the liquid metal ball tube bearing, and perform data fusion processing based on the static friction torque signal and the preliminary measurement result of the friction torque of the liquid metal ball tube bearing to obtain the actual measurement result of the friction torque of the liquid metal ball tube bearing.

[0036] As another aspect of the present invention, a friction torque measurement system for a liquid metal spherical tube bearing is provided, comprising: an acceleration sensor and a microcontroller, the acceleration sensor being communicatively connected to the microcontroller, the microcontroller including the aforementioned friction torque measurement device for a liquid metal spherical tube bearing; the acceleration sensor being disposed on the outer surface of a metal cover of the liquid metal spherical tube, the metal cover of the liquid metal spherical tube containing a target plate and a bearing in a vacuum environment;

[0037] The acceleration sensor is used to generate a measurement signal when the bearing drives the target plate to rotate;

[0038] The friction torque measuring device of the liquid metal ball tube bearing is used to process and analyze the measurement signal of the acceleration sensor when the rotation speed of the target disk reaches a preset rotation speed threshold to obtain the actual measurement result of the friction torque of the liquid metal ball tube bearing.

[0039] Furthermore, it also includes a host computer, which is communicatively connected to the microcontroller, and is used to receive the actual measurement results of the friction torque of the liquid metal ball tube bearing, and perform visualization processing based on the actual measurement results of the friction torque of the liquid metal ball tube bearing to obtain visualization information, wherein the visualization information at least includes instantaneous information and change trend information of the friction torque of the liquid metal ball tube bearing.

[0040] The present invention provides a method for measuring the friction torque of a liquid metal spherical tube bearing. The method comprises the following steps: an acceleration sensor is arranged on the outer surface of a metal cover of a liquid metal spherical tube, and after obtaining a measurement signal from the acceleration sensor when the rotation speed of the target disk reaches a preset rotation speed threshold, the obtained measurement signal is filtered and pre-processed, and a time-domain to frequency-domain conversion process is performed on the obtained measurement signal to obtain the instantaneous rotation speed of the liquid metal spherical tube bearing. The initial measurement result of the friction torque of the liquid metal bearing is determined based on the instantaneous rotation speed. Finally, the actual measurement result of the friction torque of the liquid metal spherical tube bearing is obtained by combining the static friction torque signal with the instantaneous information of the rotation of the liquid metal spherical tube bearing itself. The method for measuring the friction torque of the liquid metal spherical tube bearing uses an acceleration sensor combined with a spectrum analysis method to convert vibration into frequency, and then combines the frequency with the actual moment of inertia of the liquid metal spherical tube rotor to calculate the friction torque of the liquid metal bearing through an algorithm. The method can accurately measure the friction torque of the liquid metal bearing in a metal cover with a vacuum environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present invention, but do not constitute a limitation of the present invention.

[0042] Figure 1 The present invention provides a structural schematic diagram of a liquid metal ball tube.

[0043] Figure 2 This is a flow chart of the friction torque measurement method of the liquid metal ball tube bearing provided by the present invention.

[0044] Figure 3 This is a flow chart of filtering and preprocessing the measurement signal of the acceleration sensor provided by the present invention.

[0045] Figure 4 This is a circuit schematic diagram of the filter circuit provided by the present invention.

[0046] Figure 5 The present invention provides a flow chart for performing time-domain to frequency-domain processing on the measurement preprocessing signal of the acceleration sensor.

[0047] Figure 6 A flow chart for determining preliminary measurement results of the friction torque of a liquid metal ball tube bearing provided by the present invention.

[0048] Figure 7 A flow chart for determining the angular acceleration of a liquid metal ball tube bearing provided by the present invention.

[0049] Figure 8 2D diagram of the rotating component provided by the present invention.

[0050] Figure 9 A flow chart for obtaining actual measurement results of the friction torque of a liquid metal ball tube bearing provided by the present invention.

[0051] Figure 10 The image of rotation speed and friction torque displayed by the host computer provided by the present invention.

[0052] Figure 11 This is a structural block diagram of the friction torque measuring device for the liquid metal ball tube bearing provided by the present invention. DETAILED DESCRIPTION

[0053] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention may be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0054] In order to make the technical personnel in the art better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by the ordinary skilled in the art without creative labor should be within the scope of protection of the present application.

[0055] It should be noted that the terms "first", "second" and the like in the specification and claims of the present application and the above-described drawings are used to distinguish similar objects, and do not necessarily indicate a specific order or a chronological sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances to describe the embodiments of the present application described herein. In addition, the terms "comprise" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device including a series of steps or units does not have to be limited to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0056] In the present embodiment, a friction torque measurement method of a liquid metal ball bearing is provided, as shown in Figure 1 The outer surface of the metal cover 1 of the liquid metal ball bearing is provided with an acceleration sensor 7, and the metal cover 1 of the liquid metal ball bearing is provided with a target disc 2 and a bearing 3 in a vacuum environment 5, and a liquid metal 6 is arranged around the periphery of the bearing 3, Figure 2 is a flow chart of the friction torque measurement method of the liquid metal ball bearing provided according to the embodiments of the present application, as shown in Figure 2 The friction torque measurement method of the liquid metal ball bearing comprises:

[0057] S100, acquiring a measurement signal of the acceleration sensor when the rotating speed of the target disc reaches a preset rotating speed threshold, wherein the liquid metal ball bearing can stop the anode driver output when the rotating speed of the target disc reaches the preset rotating speed threshold;

[0058] In the embodiments of the present application, the acceleration sensor can be fixed on the surface of the metal cover of the liquid metal ball bearing. At this time, the driver starts to drive the rotating target disc, and when the rotating speed of the target disc reaches the preset rotating speed threshold (for example, 1200 RPM), the anode driver output is stopped. At this time, the liquid metal ball bearing is only subjected to friction and decelerates, and the torque borne by the bearing is the friction torque. Therefore, the acceleration sensor signal is collected at the same time when the anode output is stopped.

[0059] S200, performing filtering preprocessing on the measurement signal of the acceleration sensor to obtain a measurement preprocessing signal of the acceleration sensor;

[0060] In an embodiment of the present invention, the measurement signal of the acceleration sensor can be filtered to filter out high-frequency interference signals; then, smooth attenuation filtering is performed on both ends of the signal to reduce the high-frequency interference caused by the edge truncation effect of the finite signal, thereby improving the accuracy of the acceleration sensor signal and finally obtaining the measurement preprocessing signal of the acceleration sensor.

[0061] S300, performing time-domain-to-frequency-domain processing on the measurement preprocessed signal of the acceleration sensor to obtain the instantaneous rotational speed of the liquid metal ball tube bearing;

[0062] For the measurement preprocessing signal of the acceleration sensor, since it is an analog signal, it can be processed from time domain to frequency domain, that is, the time domain analog signal is converted into a frequency domain signal, so that the instantaneous speed of the liquid metal ball tube bearing can be obtained based on the characteristic frequency of the frequency domain.

[0063] S400, determining a preliminary measurement result of the friction torque of the liquid metal spherical tube bearing according to the instantaneous rotational speed of the liquid metal spherical tube bearing;

[0064] In an embodiment of the present invention, in order to obtain the actual value of the friction torque, the instantaneous rotational speed of the liquid metal ball tube bearing is further processed. In this process, the initial measurement result of the friction torque of the liquid metal ball tube bearing is obtained after the processing.

[0065] S500: Acquire a static friction torque signal of the liquid metal spherical tube bearing, and perform data fusion processing on the static friction torque signal and a preliminary measurement result of the friction torque of the liquid metal spherical tube bearing to obtain an actual measurement result of the friction torque of the liquid metal spherical tube bearing.

[0066] In this embodiment of the present invention, because the rotational scenario of a liquid metal spherical tube bearing is highly dynamic and noisy, the measurement signal contains not only the instantaneous information of the bearing's own rotation but also the vibration signals generated by components on the CT gantry during high-speed rotation (revolution). To ensure that the obtained friction torque is closer to the actual value, a static friction torque signal of the liquid metal spherical tube bearing is obtained. Data fusion processing is performed on the static friction torque signal and the preliminary measurement results of the liquid metal spherical tube bearing's friction torque to obtain the actual measurement results of the liquid metal spherical tube bearing's friction torque. This actual measurement result of the liquid metal spherical tube bearing's friction torque takes into account the instantaneous information of the bearing's own rotation and, in combination with the static friction torque signal, makes the final actual measurement results of the liquid metal spherical tube bearing's friction torque more accurate.

[0067] Therefore, the liquid metal ball bearing friction torque measurement method provided by the application, by setting an acceleration sensor on the outer surface of the metal cover of the liquid metal ball bearing, and obtaining the measurement signal of the acceleration sensor when the rotating speed of the target plate reaches the preset rotating speed threshold, the obtained measurement signal is pre-processed by filtering and time domain to frequency domain processing, the instantaneous rotating speed of the liquid metal ball bearing is obtained, and then the friction torque preliminary measurement result of the liquid metal bearing is determined based on the instantaneous rotating speed, and finally the actual measurement result of the liquid metal ball bearing friction torque is obtained by considering the instantaneous information of the rotation of the liquid metal ball bearing itself and combining the static friction torque signal. The liquid metal ball bearing friction torque measurement method uses an acceleration sensor combined with a frequency spectrum analysis method to convert vibration into frequency, and then combines the actual liquid metal ball bearing rotor moment of inertia to calculate the friction torque of the liquid metal bearing by algorithm, which can accurately measure the friction torque of the liquid metal bearing in the metal cover in the vacuum environment.

[0068] In the embodiment of the application, as shown in Figure 3 The measurement signal of the acceleration sensor is pre-processed by filtering to obtain the measurement pre-processing signal of the acceleration sensor, including:

[0069] S210, the measurement signal of the acceleration sensor is pre-processed by filtering to filter out high-frequency interference signals, and the preliminary filtering result of the acceleration sensor is obtained.

[0070] In the embodiment of the application, when the measurement signal of the acceleration sensor is pre-processed by filtering, the high-frequency interference can be filtered out by a filter circuit, and the circuit schematic diagram of the filter circuit is as shown in Figure 4 The input signal Vi is processed by a second-order low-pass active filter to filter out high-frequency noise with a frequency f>1 / 2*pi*R1*C1, and the filter cutoff frequency is set to more than 5 times the fundamental wave, and the signal component with a frequency greater than 5*f will be attenuated at a speed of 40db / dec, so that the real signal can be retained and the high-frequency interference signal can be effectively filtered out.

[0071] S220, the preliminary filtering result of the acceleration sensor is processed by smoothing and attenuation to obtain the measurement pre-processing signal of the acceleration sensor.

[0072] In an embodiment of the present invention, the preliminary filtering result of the acceleration sensor is specifically filtered. Specifically, the filtering uses a Hanning window to smoothly attenuate both ends of the signal. Its time domain expression is: w(n)=0.5(1-cos(2*pi*n / (n-1))). The use of Hanning window filtering in the embodiment of the present invention can reduce the high-frequency interference caused by the edge truncation effect of the finite signal, that is, reduce the spectrum leakage phenomenon in the spectrum analysis, thereby improving the accuracy of the spectrum analysis. The specific technical process of the embodiment of the present invention when performing Hanning window filtering includes:

[0073] 1) Determine the filter specifications. The key parameters are the passband cutoff frequency fp (2.5kHz), the stopband cutoff frequency fs (12.5Hz), the stopband attenuation, and the sampling rate Fs;

[0074] 2) Calculate the ideal filter response. The impulse response of the ideal low-pass filter is obtained by the inverse Fourier transform (IDFT) in Indicates the target frequency response;

[0075] 3) Generate Hanning window and add window. Estimation window length ;

[0076] 4) Multiply the ideal finite impulse response (FIR) by the Hanning window point by point to obtain the FIR coefficient h;

[0077] 5) Directly calculate the linear convolution of the input signal and the filter impulse response. This method is applicable to FIR filters (without feedback). The calculation formula is: , where h represents the FIR coefficient obtained in the previous step. After calculation, the window filtering of the signal is realized.

[0078] In the embodiment of the present invention, the instantaneous speed of the liquid metal ball tube bearing is obtained by converting the measurement preprocessing signal of the acceleration sensor into the frequency domain, such as Figure 5 Shown, including:

[0079] S310, performing a short-time Fourier transform on the measurement preprocessing signal of the acceleration sensor to convert the measurement preprocessing signal of the acceleration sensor in the time domain into the measurement preprocessing signal of the acceleration sensor in the frequency domain;

[0080] In the embodiment of the present invention, since the friction torque requires fast and stable rotational speed measurement, a short-time Fourier transform (STFT) is performed on the windowed signal to convert the time-domain analog signal into a frequency-domain signal.

[0081] The complex spectrum X[m,k] is obtained by STFT transformation of the windowed filtered signal. The calculation formula of STFT is: , where m represents the frame miniature and k is the frequency index. Arrange the spectrum of each frame in chronological order to form a two-dimensional matrix S, where the row elements are the frequency index k (in the range 0 ≤ k ≤ NFFT / 2) and the column elements are the time index m (corresponding to the frame center time tm = m*Thop).

[0082] S320 . Obtain the instantaneous rotational speed of the liquid metal ball tube bearing according to the preprocessed measurement signal of the acceleration sensor in the frequency domain.

[0083] Specifically, the time-frequency spectrum can be obtained by taking the modulus value and normalizing the above results. Scan the time-frequency matrix time by time point and search for the maximum value on the frequency axis. , that is, searching for the frequency with the highest energy in the transition interval of the time-frequency diagram, which is the characteristic frequency of the synchronization of the rotating parts.

[0084] The instantaneous speed of the liquid metal bearing can be obtained by RPM=fpeak*60.

[0085] In the embodiment of the present invention, Figure 6 As shown, the preliminary measurement result of the friction torque of the liquid metal ball tube bearing is determined according to the instantaneous rotation speed of the liquid metal ball tube bearing, including:

[0086] S410, determining the angular acceleration of the liquid metal ball tube bearing according to the instantaneous rotational speed of the liquid metal ball tube bearing;

[0087] In order to obtain the actual value of the friction torque, the instantaneous rotation speed is further processed. Specifically, the angular acceleration of the liquid metal ball tube bearing is determined according to the instantaneous rotation speed of the liquid metal ball tube bearing, such as Figure 7 Shown, including:

[0088] S411, determining an instantaneous speed difference based on two adjacent instantaneous speeds of the liquid metal ball tube bearing;

[0089] It should be understood that the instantaneous speed f(n) is calculated at each time interval, and the instantaneous speed difference fdiff can be obtained by differentiating the speeds of two adjacent times with respect to time, that is, fdiff=f(n)-f(n-1).

[0090] S412, converting the instantaneous rotation speed difference into an angular velocity difference;

[0091] Specifically, the instantaneous rotational speed difference is converted into angular velocity difference (wdiff=fdiff*2*pi).

[0092] S413. Determine the angular acceleration of the liquid metal ball tube bearing according to the angular velocity difference.

[0093] Specifically, the angular velocity difference is differentiated with respect to time, and its expression is: waccl=d(wdiff) / d(t), that is, the angular acceleration value is obtained.

[0094] S420. Determine a preliminary measurement result of the friction torque of the liquid metal spherical tube bearing according to the angular acceleration of the liquid metal spherical tube bearing and in combination with the moment of inertia of the liquid metal spherical tube bearing.

[0095] In the embodiment of the present invention, according to the formula: friction torque = angular acceleration * moment of inertia (T = waccl * J). Specifically, the moment of inertia of the continuous irregular target plate plus the rotating shaft can be obtained by simulation using mechanical design software. Figure 8 As shown, the simulation result of the moment of inertia of the rotating component is 4.69kg*mm 2 .

[0096] In an embodiment of the present invention, a static friction torque signal of the liquid metal ball tube bearing is obtained, and data fusion processing is performed based on the static friction torque signal and the preliminary measurement result of the friction torque of the liquid metal ball tube bearing to obtain the actual measurement result of the friction torque of the liquid metal ball tube bearing, such as Figure 9 Shown, including:

[0097] S510, collecting a static friction torque signal of a static torque sensor installed on the liquid metal ball tube bearing;

[0098] Specifically, since the liquid metal bearing rotation scene is a high-dynamic and high-noise scene, the measurement signal contains not only the instantaneous information of the bearing's own rotation, but also the vibration signal generated by the components on the CT gantry during high-speed rotation (revolution). In order to make the obtained friction torque closer to the actual value, such as Figure 1 As shown, a static torque sensor 4 is added to the bearing 3, from which a static friction torque signal can be obtained.

[0099] S520, cross-validating the static friction torque signal and the preliminary friction torque measurement result to obtain the static friction torque signal and the preliminary friction torque measurement result after removing abnormal values;

[0100] Specifically, the static torque signal measured by the static torque sensor and the preliminary friction torque measurement result calculated by the acceleration sensor are subjected to data fusion processing. The preliminary friction torque measurement result T1 obtained by the acceleration sensor and the static friction torque value T2 measured by the static torque meter are cross-validated to eliminate outliers. Specifically, because the CT gantry rotation speed is stable (up to 240 rpm), when the rotation speed difference obtained by the acceleration sensor is extremely small, and the value converted to friction torque should be close to 0, the converted friction torque value is much smaller than the measurement value measured by the static friction torque meter. Based on this, it can be determined that the preliminary friction torque measurement result T1 obtained by the acceleration sensor is an outlier. This outlier is actually generated on the sensor by the revolution of the tube on the CT gantry, and is therefore eliminated.

[0101] S530 , performing weighted fusion on the static friction torque signal after removing abnormal values ​​and the preliminary friction torque measurement result in a weighted fusion manner to obtain an actual measurement result of the friction torque of the liquid metal ball tube bearing.

[0102] In an embodiment of the present invention, the above results are processed by weighted fusion, the weight of the acceleration sensor is set to 0.7, the weight of the static torque sensor is set to 0.3, and the actual measurement result of the friction torque of the liquid metal ball tube bearing is output as T=0.7*T1+0.3*T2. This method can more accurately filter out external interference to obtain more precise friction torque information, and also has better anti-interference ability.

[0103] In an embodiment of the present invention, the method for measuring the friction torque of a liquid metal ball tube bearing further includes:

[0104] The actual measurement result of the friction torque of the liquid metal ball tube bearing is sent to a host computer, so that the host computer generates visualization information of the friction torque of the liquid metal ball tube bearing according to the actual measurement result of the friction torque of the liquid metal ball tube bearing.

[0105] It should be understood that after obtaining the actual measurement results of the friction torque of the liquid metal ball tube bearing, the speed and torque information are transmitted to the host computer via UART communication. A graph is drawn with the speed and friction torque data as the vertical axis and time as the horizontal axis, as shown in the following figure: Figure 10 The upper part is the speed image, and the lower part is the friction torque image.

[0106] In this embodiment of the present invention, the desired instantaneous value and trend of friction torque were ultimately obtained. The initial friction torque value measured by this method ranged from 0.12 Nm to 0.15 Nm, and the slope of the friction torque gradually decreased with increasing free rotation time. A torque of approximately 0.05 Nm at the landing point of the liquid metal bearing indicates that the performance of the liquid metal bearing meets the requirements.

[0107] In summary, the friction torque measurement method of the liquid metal spherical tube bearing provided by the present invention converts vibration into frequency, and then combines the frequency with the actual rotational inertia of the liquid metal spherical tube rotor to calculate the friction torque of the liquid metal bearing through an algorithm. This method can accurately measure the friction torque of the liquid metal bearing in a metal cover with a vacuum environment inside.

[0108] As another embodiment of the present invention, a friction torque measurement device for a liquid metal ball tube bearing is provided, which is used to implement the friction torque measurement method of the liquid metal ball tube bearing described above, wherein an acceleration sensor is provided on the outer surface of the metal cover of the liquid metal ball tube, and a target plate is provided in a vacuum environment inside the metal cover of the liquid metal ball tube, such as Figure 11 As shown, the friction torque measuring device 100 of the liquid metal ball tube bearing includes:

[0109] an acquisition module 110, configured to acquire a measurement signal from the acceleration sensor when the rotation speed of the target disk reaches a preset rotation speed threshold, wherein the liquid metal bulb is capable of stopping the output of the anode driver when the rotation speed of the target disk reaches the preset rotation speed threshold;

[0110] The preprocessing module 120 is configured to perform filtering preprocessing on the measurement signal of the acceleration sensor to obtain a measurement preprocessing signal of the acceleration sensor;

[0111] The conversion module 130 is used to perform time-domain to frequency-domain processing on the measurement preprocessed signal of the acceleration sensor to obtain the instantaneous rotation speed of the liquid metal ball tube bearing;

[0112] a preliminary result determination module 140, configured to determine a preliminary measurement result of the friction torque of the liquid metal spherical tube bearing according to the instantaneous rotational speed of the liquid metal spherical tube bearing;

[0113] The actual result acquisition module 150 is used to obtain the static friction torque signal of the liquid metal ball tube bearing, and perform data fusion processing based on the static friction torque signal and the preliminary measurement result of the friction torque of the liquid metal ball tube bearing to obtain the actual measurement result of the friction torque of the liquid metal ball tube bearing.

[0114] The friction torque measuring device for a liquid metal tube bearing provided by the present invention is configured to obtain a measurement signal of the acceleration sensor when the rotation speed of the target disc reaches a preset rotation speed threshold by arranging an acceleration sensor on the outer surface of the metal cover of the liquid metal tube. The acceleration sensor performs filtering preprocessing and time-domain to frequency-domain processing on the obtained measurement signal to obtain the instantaneous rotation speed of the liquid metal tube bearing. The initial measurement result of the friction torque of the liquid metal bearing is determined based on the instantaneous rotation speed. Finally, the actual measurement result of the friction torque of the liquid metal tube bearing is obtained by combining the static friction torque signal with the instantaneous information of the rotation of the liquid metal tube bearing itself. The friction torque measuring device for a liquid metal tube bearing uses an acceleration sensor combined with a spectrum analysis method to convert vibration into frequency, and then combines the frequency with the actual moment of inertia of the liquid metal tube rotor to calculate the friction torque of the liquid metal bearing through an algorithm. The friction torque of the liquid metal bearing can be accurately measured in a metal cover with a vacuum environment.

[0115] The specific working principle of the friction torque measuring device of the liquid metal ball tube bearing provided by the present invention can be referred to the description of the friction torque measuring method of the liquid metal ball tube bearing in the above text, and will not be repeated here.

[0116] As another embodiment of the present invention, a friction torque measurement system for a liquid metal ball tube bearing is provided, which includes: an acceleration sensor and a microcontroller, wherein the acceleration sensor is communicatively connected to the microcontroller, and the microcontroller includes the friction torque measurement device for the liquid metal ball tube bearing described above, such as Figure 1 As shown, the acceleration sensor 7 is arranged on the outer surface of the metal cover 1 of the liquid metal tube, and the metal cover 1 of the liquid metal tube is provided with a target plate 1 and a bearing 3 located in a vacuum environment 5;

[0117] The acceleration sensor is used to generate a measurement signal when the bearing drives the target plate to rotate;

[0118] The friction torque measuring device of the liquid metal ball tube bearing is used to process and analyze the measurement signal of the acceleration sensor when the rotation speed of the target disk reaches a preset rotation speed threshold to obtain the actual measurement result of the friction torque of the liquid metal ball tube bearing.

[0119] In an embodiment of the present invention, a host computer is further included, which is communicatively connected to the microcontroller. The host computer is used to receive the actual measurement results of the friction torque of the liquid metal ball tube bearing, and perform visualization processing based on the actual measurement results of the friction torque of the liquid metal ball tube bearing to obtain visualization information, wherein the visualization information at least includes instantaneous information and change trend information of the friction torque of the liquid metal ball tube bearing.

[0120] In the embodiment of the present application, the instantaneous value and variation trend of the required friction torque are obtained, the initial value of the measured friction torque is between 0.12 Nm and 0.15 Nm, and the variation slope of the friction torque is gradually reduced with the extension of the free rotation time. When the torque of the landing point of the liquid metal bearing is about 0.05 Nm, it indicates that the performance of the liquid metal bearing meets the standard.

[0121] The friction torque measurement system of the liquid metal ball tube bearing provided by the present application comprises an acceleration sensor arranged on the outer surface of the metal cover of the liquid metal ball tube, and the measurement signal of the acceleration sensor is obtained when the rotating speed of the target disc reaches a preset rotating speed threshold. The obtained measurement signal is preprocessed by filtering and time domain to frequency domain processing, the instantaneous rotating speed of the liquid metal ball tube bearing is obtained, the preliminary measurement result of the friction torque of the liquid metal bearing is determined based on the instantaneous rotating speed, and finally the actual measurement result of the friction torque of the liquid metal ball tube bearing is obtained by considering the instantaneous information of the rotation of the liquid metal ball tube bearing itself and combining the static friction torque signal. The friction torque measurement system of the liquid metal ball tube bearing uses the acceleration sensor combined with the frequency spectrum analysis method to convert the vibration into frequency, and then combines the actual rotating inertia of the liquid metal ball tube rotor to calculate the friction torque of the liquid metal bearing by algorithm, so that the friction torque of the liquid metal bearing in the metal cover in the vacuum environment can be accurately measured.

[0122] The specific working principle of the friction torque measurement system of the liquid metal ball tube bearing provided by the present application can refer to the description of the friction torque measurement method of the liquid metal ball tube bearing in the foregoing, which will not be repeated here.

[0123] It can be understood that the above embodiments are only exemplary embodiments for illustrating the principles of the present application, and the present application is not limited thereto. Various modifications and improvements can be made by those skilled in the art without departing from the spirit and essence of the present application, and these modifications and improvements are also regarded as the protection scope of the present application.

Claims

1. A method for measuring the friction torque of a liquid metal ball tube bearing, characterized in that: An acceleration sensor is provided on the outer surface of a metal cover of a liquid metal tube. A target plate and a bearing are provided in a vacuum environment inside the metal cover of the liquid metal tube. The friction torque measurement method of the liquid metal tube bearing includes: acquiring a measurement signal from the acceleration sensor when the rotation speed of the target disk reaches a preset rotation speed threshold, wherein the liquid metal bulb is capable of stopping the output of the anode driver when the rotation speed of the target disk reaches the preset rotation speed threshold; Performing filtering preprocessing on the measurement signal of the acceleration sensor to obtain a measurement preprocessing signal of the acceleration sensor; Performing time-domain to frequency-domain processing on the measurement preprocessing signal of the acceleration sensor to obtain the instantaneous rotation speed of the liquid metal ball tube bearing; determining a preliminary measurement result of the friction torque of the liquid metal spherical tube bearing according to the instantaneous rotational speed of the liquid metal spherical tube bearing; Acquiring a static friction torque signal of the liquid metal spherical tube bearing, and performing data fusion processing on the static friction torque signal and a preliminary measurement result of the friction torque of the liquid metal spherical tube bearing to obtain an actual measurement result of the friction torque of the liquid metal spherical tube bearing; Determining preliminary measurement results of the friction torque of the liquid metal spherical tube bearing according to the instantaneous rotational speed of the liquid metal spherical tube bearing includes: determining the angular acceleration of the liquid metal spherical tube bearing according to the instantaneous rotational speed of the liquid metal spherical tube bearing; Determining a preliminary measurement result of the friction torque of the liquid metal spherical tube bearing based on the angular acceleration of the liquid metal spherical tube bearing and in combination with the moment of inertia of the liquid metal spherical tube bearing; Determining the angular acceleration of the liquid metal spherical tube bearing according to the instantaneous rotational speed of the liquid metal spherical tube bearing comprises: Determining the instantaneous speed difference according to two adjacent instantaneous speeds of the liquid metal ball tube bearing; Converting the instantaneous rotational speed difference into an angular velocity difference; determining the angular acceleration of the liquid metal ball tube bearing according to the angular velocity difference; Obtaining a static friction torque signal of the liquid metal spherical tube bearing, and performing data fusion processing on the static friction torque signal and a preliminary measurement result of the friction torque of the liquid metal spherical tube bearing to obtain an actual measurement result of the friction torque of the liquid metal spherical tube bearing, including: collecting a static friction torque signal of a static torque sensor mounted on the liquid metal ball tube bearing; Cross-validating the static friction torque signal and the preliminary friction torque measurement result to obtain the static friction torque signal and the preliminary friction torque measurement result after removing abnormal values; The static friction torque signal after removing abnormal values ​​and the preliminary measurement result of friction torque are weightedly fused in a weighted fusion manner to obtain the actual measurement result of friction torque of the liquid metal ball tube bearing.

2. The method for measuring the friction torque of a liquid metal ball tube bearing according to claim 1, characterized in that: Performing filtering preprocessing on the measurement signal of the acceleration sensor to obtain the measurement preprocessed signal of the acceleration sensor includes: Performing preliminary filtering processing on the measurement signal of the acceleration sensor to filter out high-frequency interference signals and obtain a preliminary filtering result of the acceleration sensor; A smoothing attenuation process is performed on the preliminary filtering result of the acceleration sensor to obtain a measurement preprocessing signal of the acceleration sensor.

3. The method for measuring the friction torque of a liquid metal ball tube bearing according to claim 1, characterized in that: The instantaneous rotation speed of the liquid metal ball tube bearing is obtained after performing time-domain to frequency-domain processing on the measurement preprocessing signal of the acceleration sensor, including: Performing short-time Fourier transform on the measurement preprocessing signal of the acceleration sensor to convert the measurement preprocessing signal of the acceleration sensor in the time domain into the measurement preprocessing signal of the acceleration sensor in the frequency domain; The instantaneous rotational speed of the liquid metal ball tube bearing is obtained according to the measurement preprocessing signal of the acceleration sensor in the frequency domain.

4. The method for measuring the friction torque of a liquid metal ball tube bearing according to any one of claims 1 to 3, characterized in that: Also includes: The actual measurement result of the friction torque of the liquid metal ball tube bearing is sent to a host computer, so that the host computer generates visualization information of the friction torque of the liquid metal ball tube bearing according to the actual measurement result of the friction torque of the liquid metal ball tube bearing.

5. A friction torque measuring device for a liquid metal ball tube bearing, used to implement the friction torque measuring method for a liquid metal ball tube bearing according to any one of claims 1 to 4, characterized in that: An acceleration sensor is provided on the outer surface of the metal cover of the liquid metal ball tube, and a target plate is provided in a vacuum environment inside the metal cover of the liquid metal ball tube. The friction torque measuring device of the liquid metal ball tube bearing includes: an acquisition module, configured to acquire a measurement signal from the acceleration sensor when the rotation speed of the target disk reaches a preset rotation speed threshold, wherein the liquid metal bulb is capable of stopping the output of the anode driver when the rotation speed of the target disk reaches the preset rotation speed threshold; A preprocessing module, configured to perform filtering preprocessing on the measurement signal of the acceleration sensor to obtain a measurement preprocessing signal of the acceleration sensor; A conversion module, configured to perform time-domain to frequency-domain processing on the measurement preprocessing signal of the acceleration sensor to obtain the instantaneous rotational speed of the liquid metal ball tube bearing; a preliminary result determination module, configured to determine a preliminary measurement result of the friction torque of the liquid metal spherical tube bearing according to the instantaneous rotational speed of the liquid metal spherical tube bearing; The actual result acquisition module is used to obtain the static friction torque signal of the liquid metal ball tube bearing, and perform data fusion processing based on the static friction torque signal and the preliminary measurement result of the friction torque of the liquid metal ball tube bearing to obtain the actual measurement result of the friction torque of the liquid metal ball tube bearing.

6. A friction torque measurement system for a liquid metal ball tube bearing, characterized in that: include: An acceleration sensor and a microcontroller, the acceleration sensor being communicatively connected to the microcontroller, the microcontroller including the friction torque measuring device for a liquid metal spherical tube bearing according to claim 5, the acceleration sensor being disposed on the outer surface of a metal cover of the liquid metal spherical tube, and the metal cover of the liquid metal spherical tube containing a target plate and a bearing in a vacuum environment; The acceleration sensor is used to generate a measurement signal when the bearing drives the target plate to rotate; The friction torque measuring device of the liquid metal ball tube bearing is used to process and analyze the measurement signal of the acceleration sensor when the rotation speed of the target disk reaches a preset rotation speed threshold to obtain the actual measurement result of the friction torque of the liquid metal ball tube bearing.

7. The friction torque measurement system of liquid metal ball tube bearing according to claim 6, characterized in that: It also includes a host computer, which is communicatively connected to the microcontroller. The host computer is used to receive the actual measurement results of the friction torque of the liquid metal ball tube bearing, and perform visualization processing based on the actual measurement results of the friction torque of the liquid metal ball tube bearing to obtain visualization information, wherein the visualization information at least includes instantaneous information and change trend information of the friction torque of the liquid metal ball tube bearing.

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