Inductance type wheel speed signal acquisition device

Abstract

The invention relates to an inductance type wheel speed signal acquisition device which comprises an inductance type wheel speed sensor arranged in a wheel hub area of a vehicle and used for generating an alternating sinusoidal signal in direct proportion to the rotating speed; the signal processor is used for performing interference filtering on the alternating sinusoidal signal to obtain a filtering signal, performing overspeed judgment on the filtering signal, inputting the filtering signal into the signal converter under the condition that the frequency of the filtering signal does not exceed the preset frequency, and stopping the filtering signal under the condition that the frequency of the filtering signal exceeds the preset frequency; performing overspeed alarm processing; the signal converter is used for comparing the filtering signal with a reference voltage to obtain a comparison result, and performing PWM conversion on the comparison result to obtain a PWM signal; and the wheel speed capturer is used for capturing the PWM signal by utilizing the PWM sampling port and calculating the PWM signal by utilizing the number of turns of the gear ring to obtain the current wheel speed of the wheel. The device is high in detection precision and strong in anti-interference capability in a low-speed scene.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of wheel speed signal acquisition and processing, and particularly relates to an inductance type wheel speed signal acquisition device. BACKGROUND

[0002] With the continuous high-speed growth of the automobile market for many years, people's requirements for automobile driving safety technology are also getting higher and higher, especially active safety technology. Whether it is the widely used Anti-lock Brake System (ABS), Electronic Stability Program (ESP), or the gradually rising Advanced Driver Assistance System (ADAS), Forward Collision Warning System (FCWS), it is necessary to accurately obtain the current wheel speed, or to estimate the vehicle speed through the logic calculation of the wheel speed signal by the vehicle ECU.

[0003] However, the existing electromagnetic type acquisition device has low precision in measuring low-speed rotation data and poor anti-electromagnetic wave interference ability. In short, the existing wheel speed acquisition device has low precision in low-speed detection and weak anti-interference ability. SUMMARY

[0004] In order to solve the above problems existing in the prior art, the application provides an inductance type wheel speed signal acquisition device. The technical problem to be solved by the application is solved by the following technical scheme: The application provides an inductance type wheel speed signal acquisition device, comprising: an inductance type wheel speed sensor, a signal processor, a signal converter and a wheel speed capturer; the inductance type wheel speed sensor is arranged in the wheel hub area of a vehicle, and an alternating sinusoidal signal proportional to the rotation speed is generated by cutting the magnetic field of the inductance type wheel speed sensor through the rotation of the gear ring of the vehicle in a preset period; the signal processor is used for filtering out interference of the alternating sinusoidal signal to obtain a filtered signal, performing overspeed judgment on the filtered signal, inputting the filtered signal into the signal converter in the case where the frequency of the filtered signal is determined to be less than a predetermined frequency, and cutting off the filtered signal as an overspeed warning processing in the case where the frequency of the filtered signal is determined to exceed the predetermined frequency; the signal converter is used for comparing the filtered signal with a reference voltage to obtain a comparison result, performing PWM conversion on the comparison result to obtain a PWM signal; and the wheel speed capturer is used for capturing the PWM signal by using a PWM sampling port, calculating the PWM signal by using the number of turns of the gear ring, and obtaining the current wheel speed.

[0005] In some embodiments, the signal processor comprises: a high-pass filter and a low-pass filter; wherein the high-pass filter is configured to high-pass filter the alternating sinusoidal signal to filter out DC signal interference to obtain the filtered signal; and the low-pass filter is configured to perform overspeed judgment on the filtered signal.

[0006] In some embodiments, the comparison result comprises: outputting a low-level signal when the voltage value of the filtered signal drops to a first reference voltage, outputting a high-level signal when the voltage value of the filtered signal rises above a second reference voltage, and performing PWM conversion on the low-level signal or the high-level signal to obtain the PWM signal.

[0007] In some embodiments, the calculation expression of the wheel speed satisfies: ; wherein, is the wheel speed, is the frequency of the alternating sinusoidal signal, is the preset period, is the number of rings of the ring gear.

[0008] In some embodiments, the signal processor is further configured to: continuously monitor the frequency of the input signal after the filtered signal is obtained; and automatically release the signal cutoff state when it is monitored that the frequency of the input signal falls below the predetermined frequency.

[0009] In some embodiments, the cutoff frequency of the high-pass filter is set to 0.1 Hz-10 Hz, the cutoff frequency of the low-pass filter is set to 1 kHz-10 kHz, and the phase shift of the low-pass filter is not more than ±45°.

[0010] In some embodiments, further comprising: a dynamic voltage regulation module configured to generate the first reference voltage and the second reference voltage, and to synchronously adjust the values of the first reference voltage and the second reference voltage according to the following formula: ; wherein, is the first reference voltage, is the second reference voltage, is the peak voltage of the filtered signal, and is a proportional coefficient, and .

[0011] In some embodiments, the signal converter is a hysteresis comparator.

[0012] Compared with the prior art, the present application has the following advantages: In view of the problem of low detection precision and weak anti-interference ability of the existing wheel speed acquisition device, the embodiment of the present application provides an inductive wheel speed signal acquisition device, which generates a sinusoidal signal through the coupling of an inductive wheel speed sensor and a gear ring magnetic field, triggers active warning by a low-pass filter hardware level overspeed cutoff after eliminating DC interference through high-pass filtering, and converts a noise-resistant PWM signal by using a signal converter dynamic reference voltage, so as to finally realize high-precision wheel speed calculation in the full speed range in combination with gear ring parameters, and has the automatic recovery ability of overspeed state, thereby solving the defects of the traditional scheme in low-speed precision, anti-interference and safety warning. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 is a structural block diagram of an inductive wheel speed signal acquisition device provided by the embodiment of the present application; Figure 2 is a setting position and working principle example diagram of an inductive wheel speed sensor provided by the embodiment of the present application; Figure 3 is a gain and phase change diagram of a low-pass filter provided by the embodiment of the present application; Figure 4 is a simulation circuit diagram of the inductive wheel speed signal acquisition device provided by the embodiment of the present application; Figure 5 is an output signal waveform change example diagram of a hysteresis comparator and a wheel speed capturer under a 100KHz alternating sinusoidal signal provided by the embodiment of the present application; Figure 6 is an output signal waveform change example diagram of a hysteresis comparator and a wheel speed capturer under a 50KHz alternating sinusoidal signal provided by the embodiment of the present application; Figure 7 is an output signal waveform change example diagram of a hysteresis comparator and a wheel speed capturer under a 5KHz alternating sinusoidal signal provided by the embodiment of the present application. DETAILED DESCRIPTION

[0014] The present application will be further described in detail below in combination with specific embodiments, but the embodiments of the present application are not limited thereto.

[0015] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and integrate different embodiments or examples described in the present specification.

[0016] Although the present application is described herein in connection with various embodiments, those skilled in the art will understand and appreciate the disclosure of the described embodiments that other variations can be understood and effected by those skilled in the art in practicing the claimed application, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other components or steps, and the indefinite article "a" or "an" does not exclude a plurality. A single processor or other unit can implement several functions listed in the claims. Measures described in mutually different dependent claims can be combined and produce desirable results.

[0017] An inductive wheel speed signal acquisition device according to an embodiment of the present application will now be described in detail with reference to the accompanying drawings.

[0018] Figure 1 is a structural block diagram of an inductive wheel speed signal acquisition device provided by an embodiment of the present application. As shown in Figure 1 the device includes an inductive wheel speed sensor, a signal processor, a signal converter, and a wheel speed capturer; the inductive wheel speed sensor is arranged in a wheel hub area of a vehicle, and generates an alternating sine signal proportional to the rotational speed by cutting the magnetic field of the inductive wheel speed sensor through the rotation of the gear ring of the vehicle within a predetermined period; the signal processor is used to filter out interference from the alternating sine signal to obtain a filtered signal, to perform overspeed judgment on the filtered signal, to input the filtered signal to the signal converter in the case where the frequency of the filtered signal is determined not to exceed a predetermined frequency, and to cut off the filtered signal as an overspeed warning process in the case where the frequency of the filtered signal is determined to exceed the predetermined frequency; the signal converter is used to compare the filtered signal with a reference voltage to obtain a comparison result, and to perform PWM conversion on the comparison result to obtain a PWM signal; and the wheel speed capturer is used to capture the PWM signal by using a PWM sampling port, to calculate the PWM signal by using the number of turns of the gear ring, and to obtain the current wheel speed of the vehicle.

[0019] Figure 2 is an example diagram of the arrangement position and working principle of an inductive wheel speed sensor provided by an embodiment of the present application. As shown inFigure 2 As shown, the sensor body is fixed on the knuckle or suspension bracket by bolts, and the probe end face keeps a clearance of 0.3mm-1.0mm with the gear ring of the wheel hub bearing; the working principle is that the gear ring teeth of the wheel rotate periodically cut the sensor magnetic field, and based on the electromagnetic induction principle, a sine wave signal (induced electromotive force) strictly proportional to the rotation speed is generated in the coil, realizing non-contact wheel speed acquisition.

[0020] Here, specifically, the signal processor comprises: a high-pass filter and a low-pass filter; wherein the high-pass filter is used for high-pass filtering the alternating sine signal to filter out the DC signal interference to obtain a filtered signal; the low-pass filter is used for over-speed judgment on the filtered signal. The cutoff frequency of the high-pass filter is set to 0.1Hz-10Hz, and the cutoff frequency of the low-pass filter is set to 1kHz-10kHz; and the phase shift of the low-pass filter does not exceed ±45°. And the signal processor is further used for: continuously monitoring the frequency of the input signal after the filtered signal is cut off; when the frequency of the input signal is monitored to fall below a predetermined frequency, the signal cutoff state is automatically released.

[0021] Exemplarily, the high-pass filter adopts the principle of capacitive DC blocking, allowing alternating signals higher than the cutoff frequency (typical value 0.1-10Hz) to pass through, while directly leading the DC offset (such as temperature drift, power supply noise) in the vehicle circuit to the ground terminal, eliminating its basic interference on the sine wave signal. The low-pass filter is based on the inductance / capacitance high-frequency attenuation mechanism, and sets an over-speed threshold frequency (such as 5kHz), when the input signal frequency is lower than this value, it passes through without loss; once the frequency exceeds the threshold, the filter attenuates the signal amplitude below the -3dB point, triggering the hardware level over-speed cutoff. At the same time, the input frequency is continuously monitored, and when it falls below the threshold, it is automatically restored after a delay, avoiding critical state jitter, and realizing the dynamic release of the safety mechanism.

[0022] The phase shift of the low-pass filter does not exceed ±45°, which can ensure that the signal zero-crossing point is not distorted. Figure 3 is the gain and phase change diagram of the low-pass filter provided by the embodiment of the application. Wherein, the coordinate axes on the left and right sides are coordinates, and the horizontal axis is frequency. The red curve in the figure represents the gain of the low-pass filter, and the blue curve represents the phase change of the output waveform of the low-pass filter. Wherein, the curve equation of the red curve is , and the curve equation of the blue curve is ; , The value of C is 0.1μf, The value is 330Ω, the tracking point coordinate value X is 4841.7, the value Y is -3.0273, and the value Y1 is -6.0545. As can be seen from the figure, when the frequency reaches 5KHz, the gain of the low-pass filter decreases and the phase shift is 42°, that is, the low-pass filter has good passability to low-frequency signals and attenuation effect to high-frequency signals, the lower the frequency, the smaller the phase, and the circuit has good robustness.

[0023] Here, the signal converter is a hysteresis comparator. The hysteresis comparator (Schmitt Trigger) is a threshold comparison circuit with voltage hysteresis characteristics, and its core principle is to eliminate false triggering caused by noise interference through double threshold design. In the commercial vehicle vibration / electromagnetic noise environment, the hysteresis comparator ensures that the PWM signal strictly corresponds to the physical position of the gear ring, avoiding false triggering of ABS / ESP due to signal jitter. Specifically, the comparison result obtained by the signal converter includes: in the case that the voltage value of the filtered signal drops to the first reference voltage, outputting a low-level signal, in the case that the voltage value of the filtered signal rises above the second reference voltage, outputting a high-level signal, and performing PWM conversion on the low-level signal or the high-level signal to obtain a PWM signal. Here, the first reference voltage is less than the second reference voltage.

[0024] In one possible implementation, the apparatus further includes a dynamic voltage adjustment module, which is configured to generate the first reference voltage and the second reference voltage, and to synchronously adjust the values of the first reference voltage and the second reference voltage according to the following formula: ; wherein, is the first reference voltage, is the second reference voltage, is the peak voltage of the filtered signal, and is a proportional coefficient, and .

[0025] Exemplarily, In the initial stage, the voltage value of the filtered signal is 1V, which is lower than the first reference voltage, and a low-level signal is outputted, in the rising stage, the voltage value of the filtered signal rises from 1V to 1.725V, which does not exceed the second reference voltage, and a low-level signal is continuously outputted, when the voltage value of the filtered signal exceeds the second reference voltage, the output jumps to a high-level signal, when the voltage value of the filtered signal falls to 1.65V (which is still greater than the second reference voltage), a high-level signal is continuously outputted, and when it falls below the first reference voltage, the output jumps to a low-level signal.

[0026] Here, the PWM signal is a digital signal, which can avoid the problem of analog signal distortion.

[0027] In a possible implementation, the calculation expression of the wheel speed satisfies: ; wherein, is the wheel speed, is the frequency of the alternating sinusoidal signal, is a preset period, is the number of gear rings.

[0028] In view of the problem that the existing wheel speed acquisition device has low detection precision at low speed and weak anti-interference ability, the embodiment of the application provides an inductive wheel speed signal acquisition device, which generates a sinusoidal signal through the coupling of an inductive sensor and a gear ring magnetic field, eliminates DC interference through high-pass filtering, triggers active warning at a hardware level through a low-pass filter, and converts a noise-resistant PWM signal through a signal converter dynamic reference voltage, and finally realizes high-precision wheel speed calculation in the full speed range by combining gear ring parameters, and has the automatic recovery ability of the overspeed state, and completely solves the defects of the traditional scheme in the low-speed precision, anti-interference and safety warning.

[0029] The performance of the inductive wheel speed signal acquisition device provided by the embodiment of the application is verified by using a simulation software ltpsice, and specifically, a corresponding circuit connection schematic diagram (as shown in Figure 4 ) is established in the simulation software, then the frequency value of the inductive wheel speed sensor output signal (Vin) is changed, and the output signal (Vvp) waveform change of the hysteresis comparator and the output signal (Vout2) waveform change of the wheel speed capturer are observed. Among them, Figure 5 is an example diagram of the output signal waveform change of the hysteresis comparator and the wheel speed capturer under the alternating sinusoidal signal of 100KHz provided by the embodiment of the application, Figure 6 is an example diagram of the output signal waveform change of the hysteresis comparator and the wheel speed capturer under the alternating sinusoidal signal of 50KHz provided by the embodiment of the application, Figure 7 is an example diagram of the output signal waveform change of the hysteresis comparator and the wheel speed capturer under the alternating sinusoidal signal of 5KHz provided by the embodiment of the application.

[0030] Based on Figures 5-7 It can be concluded that when the frequency of the alternating sinusoidal signal is 5KHz, the reference voltage is 1.65V, and the output is normal; when the frequency of the alternating sinusoidal signal is 50KHz, the in-phase terminal voltage signal amplitude of the hysteresis comparator is reduced, and the output waveform is distorted; when the frequency of the alternating sinusoidal signal is 100KHz, the waveform is completely distorted. That is, the embodiment of the application has high detection precision and strong anti-interference ability in the low-speed scene.

[0031] The above is further detailed description of the present application in combination with specific preferred embodiments, and cannot be deemed as limitation of the specific implementation of the present application to these descriptions. For those skilled in the art to which the present application belongs, without departing from the concept of the present application, a number of simple deductions or substitutions can be made, and all of them shall be deemed as falling within the protection scope of the present application.

Claims

1. An inductive wheel speed signal acquisition device, characterized in that, include: Inductive wheel speed sensor, signal processor, signal converter, and wheel speed capture device; The inductive wheel speed sensor is installed in the wheel hub area of ​​the vehicle. By rotating the gear ring of the vehicle within a preset period, it cuts the magnetic field of the inductive wheel speed sensor, generating an alternating sinusoidal signal proportional to the rotational speed. The signal processor is used to filter out interference from the alternating sinusoidal signal to obtain a filtered signal, to determine overspeed from the filtered signal, and to input the filtered signal into the signal converter if the frequency of the filtered signal does not exceed a predetermined frequency, and to cut off the filtered signal if the frequency of the filtered signal exceeds the predetermined frequency, thus acting as an overspeed alarm. The signal converter is used to compare the filtered signal with a reference voltage to obtain a comparison result, and to perform PWM conversion on the comparison result to obtain a PWM signal. The wheel speed capture device is used to capture the PWM signal using the PWM sampling port, and calculate the current wheel speed using the number of rotations of the gear ring.

2. The inductive wheel speed signal acquisition device according to claim 1, characterized in that, The signal processor includes: a high-pass filter and a low-pass filter; The high-pass filter is used to perform high-pass filtering on the alternating sinusoidal signal to filter out DC signal interference and obtain the filtered signal. The low-pass filter is used to determine overspeed in the filtered signal.

3. The inductive wheel speed signal acquisition device according to claim 1, characterized in that, The comparison results include: when the voltage value of the filtered signal drops to the first reference voltage, a low-level signal is output; when the voltage value of the filtered signal rises above the second reference voltage, a high-level signal is output; and the low-level signal or the high-level signal is converted into a PWM signal to obtain the PWM signal.

4. The inductive wheel speed signal acquisition device according to claim 1, characterized in that, The expression for calculating the wheel speed satisfies: ； in, It is the wheel speed of the mentioned wheel. It is the frequency of the alternating sinusoidal signal. It is the preset period. It is the number of turns of the gear ring.

5. The inductive wheel speed signal acquisition device according to claim 1, characterized in that, The signal processor is also used for: After the filtered signal is cut off, the frequency of the input signal is continuously monitored; When the frequency of the input signal is detected to fall below the predetermined frequency, the signal cutoff state is automatically lifted.

6. The inductive wheel speed signal acquisition device according to claim 2, characterized in that, The cutoff frequency of the high-pass filter is set to 0.1Hz~10Hz, and the cutoff frequency of the low-pass filter is set to 1kHz~10kHz; and the phase offset of the low-pass filter does not exceed ±45°.

7. The inductive wheel speed signal acquisition device according to claim 1 or 3, characterized in that, Also includes: A dynamic voltage adjustment module is used to generate a first reference voltage and a second reference voltage, and to synchronously adjust the values ​​of the first reference voltage and the second reference voltage according to the following formula: ； in, It is the first reference voltage. It is the second reference voltage. It is the peak voltage of the filtered signal. and It is a proportionality coefficient. and .

8. The inductive wheel speed signal acquisition device according to claim 7, characterized in that, The signal converter is a hysteresis comparator.

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