JPH0280964A - Apparatus for processing wheel speed signal - Google Patents

Abstract

PURPOSE:To remove the noise due to the torque pulsation of an engine from a rotational speed detection signal by setting the cut-off frequency of a filter to the frequency corresponding to the torque variation of the engine. CONSTITUTION:The rotational speed Vx of the wheel 1 of a vehicle loaded with an engine 13 is detected by a rotor 2 for a wheel speed sensor and a pickup 3 for said wheel speed sensor and, in order to remove the noise generated by the torque pulse wave of the engine 13, the cut-off frequency of a digital (CPU 5) is set to the noise frequency omega/(LPF, notch filter) at the time of the idle rotation corresponding to the torque variation of the engine 13. By this method, the noise due to the torque pulsation of the engine 13 can be certainly removed from a detection signal.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a wheel speed signal processing device used when performing O1-drive and traction control.

[Prior Art and Problems] Conventionally, wheel speed sensors are used when performing automatic drive or traction control, and noise is mixed into the signal measured by the wheel speed sensor. As a result, even though the wheel speed is constant, the wheel speed result obtained from the wheel speed sensor signal (q) pulsates due to the inclusion of the noise. In order to eliminate the influence of this noise, the wheel speed sensor υ
It is possible to weaken the signal from the source (by taking a tracking average), but it has not been possible to completely remove the noise.

An object of the present invention is to provide a wheel speed signal processing device that can reliably remove noise from a detection signal of a rotational speed detection means (wheel speed sensor) mixed with various noises.

[Means for Solving the Problems] There are two types of main noise sources in the detection signal from the wheel speed sensor: those caused by engine torque pulsations, and those caused by wheel eccentricity or sensor installation errors.

The frequency of the noise generated by engine torque pulsations changes depending on the engine speed, and the frequency is lowest and the noise amplitude is highest near the idle speed.

In addition, noise caused by wheel eccentricity or sensor installation error has a relatively low frequency, which overlaps with the frequency range required for various controls using wheel speed signals, and whose frequency varies depending on the wheel rotation speed. Change.

Therefore, focusing on these properties, the first invention includes a rotational speed detection means for detecting the rotational speed of the wheels of a vehicle equipped with an engine, and a detection signal of the rotational speed detection means is input, and a detection signal from the rotational speed detection means is inputted. The gist of the present invention is a wheel speed signal processing device comprising a filter for removing noise and a cutoff frequency setting means for setting the cutoff frequency of the filter to a frequency corresponding to engine torque fluctuations.

Furthermore, as a second invention, there is provided a rotational speed detection means for detecting the rotational speed of a wheel of a vehicle, a filter for panning the detection signal of the rotational speed detection means and removing noise therein, and The gist of the present invention is a wheel speed signal processing device comprising a cutoff frequency setting means for inputting a detection signal of a speed detection means and setting a cutoff frequency of the filter according to the rotational speed of the wheel.

[Operations] In the first invention, the rotational speed detection means detects the rotational speed of the wheels of a vehicle equipped with the engine, and the cutoff frequency setting means sets the cutoff frequency of the filter to a frequency corresponding to engine torque fluctuations. As a result, noise due to engine torque pulsation is removed from the detection signal of the rotational speed detection means by the filter whose cutoff frequency is set in this manner.

In the second invention, the rotational speed detection means detects the rotational speed of the wheel, and the cutoff frequency setting means inputs the detection signal of the rotational speed detection means and sets the cutoff frequency of the filter according to the rotational speed of the wheel. do. As a result, noise caused by wheel eccentricity, etc., is removed from the detection signal of the rotational speed detection means by the filter whose cutoff frequency is set in this manner.

[Embodiment] An embodiment in which the present invention is embodied in a wheel speed signal processing device for traction control will be described with reference to the drawings.

FIG. 1 is a schematic diagram showing the entire traction system. A wheel speed sensor rotor 2 constituting rotational speed detection means is provided on a wheel 1 of a vehicle (not shown), and the wheel speed sensor rotor 2 rotates as the wheel 1 rotates. A wheel speed sensor electromagnetic pickup 3 constituting a rotational speed detection means is disposed near the teeth of the wheel speed sensor rotor 2, and the pickup 3 generates pulses corresponding to the rotational speed of the wheel speed sensor rotor 2. Output a signal.

Although FIG. 1 shows only one of the four wheels 1, the other three wheels are also equipped with a wheel speed sensor rotor 2 and a wheel speed sensor electromagnetic pickup 3.
is being pulled.

The controller 4 as a filter and cutoff frequency setting means includes a central processing unit (hereinafter referred to as CPU) 5, a read-only memory (ROM>6), and a random access memory (
RAM>7, pulse input circuit 8, motor drive circuit 9, A
/D converter 10. The CPU 5 executes various arithmetic operations in accordance with a single control program stored in the ROM 6, and temporarily stores the results of the arithmetic operations in the RAM 7. Further, a pulse signal from the electromagnetic pickup 3 for the wheel speed sensor of each wheel 1 is inputted via the pulse input circuit 8, and the CP
U5 detects the rotational speed of the wheel 1 from this pulse signal.

Further, the detection signal of the pedal sensor 12 that detects the amount of operation of the accelerator pedal 11 is converted into a digital signal by the A/D converter 10, and the CPU 5 detects the amount of operation of the accelerator pedal 11 based on the signal from the pedal sensor 12. .

The motor drive circuit 9 is connected to the throttle valve 1 of the engine 13.
The motor 1 is connected to the motor 15 that drives the accelerator pedal 4, and the motor 1 is connected to the motor 15 that drives the accelerator pedal.
5 to control the opening degree of the throttle valve 14.

The opening degree of the throttle valve 14 is detected by the opening degree sensor 16, and the detection signal is sent to the A/D converter 10.
is converted into a digital signal.

Then, the CPLJ 5 detects the opening degree of the throttle valve 14 based on the signal from the opening sensor 16.

In order to remove noise in the pulse signal from the electromagnetic pickup 3 for the wheel speed sensor, the CPU 5 operates as shown in FIGS.
It has a digital filter function as shown in the Bode diagram in d). That is, the filter characteristic Cf1 is a characteristic of a low-pass filter for removing noise caused by torque pulsation of the engine 13, and the cutoff frequency ω1 is set to be the same as the noise frequency at idle, where the frequency is the lowest. In addition, the characteristic is a combination of a notch filter that can remove the frequency of ω1 in accordance with the maximum noise amplitude at this time.

Filter characteristics Cf 2 to (J 5 are characteristics of a notch filter for removing noise caused by wheel eccentricity and sensor installation error, and are designed to match the noise frequencies ω2, ω3, ω4, and ω5 that change depending on the wheel speed. Cf 2~C
It is possible to select the optimal one from f5 and remove only unnecessary signals. In this embodiment, the first filter F1 is obtained by combining the filter characteristic (J1) shown in FIG. 2(a) and the filter characteristic (J2), and the filter characteristic (Cf1) shown in FIG. The second filter F2 is obtained by combining the filter characteristic (J3), and the third filter F3 is obtained by combining the filter characteristic CA1 and the filter characteristic Cf4 shown in FIG. 2(C). ) The filter characteristic Cf shown in
1 and the filter characteristic Cf 5 are combined to form a fourth filter F4.

The filter coefficients of these first to fourth filters F1 to F4 are stored in the ROM 6 of the controller 4, and filtering is performed by switching the filter coefficients according to the input value of the wheel speed signal (wheel speed).

Next, the operation of the wheel speed signal processing device for traction control configured as described above will be explained based on FIG. 3.

First, in step 100, the CPU 5 determines the wheel rotational speed (
The current wheel speed Vx is calculated using that speed and the previous and two previous wheel speeds. However, the wheel speeds of the previous time and the time before the previous time are stored in the RAM 7 and are updated each time. Note that the current wheel speed Vx may be calculated by using the current value and the previous value.

Then, in step 101, the CPU 5 compares the wheel speed VX with a predetermined speed Kv1, and if the wheel speed VX is less than or equal to the speed KV1, then in step 102, the CPU 5 compares the wheel speed VX with a predetermined speed Kv1.
Set the filter coefficients shown in Figure (a). Furthermore, the CPU
5 is the speed KV which is the wheel speed VX predetermined in step 103.
2 (Compared with KV2 > KVI >, if the wheel speed Vx is less than or equal to the speed KV2 (KVI <Vx ≦KV2
) Stella”:j 104 and the second filter F2 (second
Set the filter coefficients shown in Figure (b)).

Furthermore, the CPU 5 compares the wheel speed VX with a predetermined speed KV3 (KV3 >KV2') in step 105, and if the wheel speed Vx is less than or equal to the speed KV3 (K
x≦Kv3) In step 106, the filter coefficients of the third filter F3 (FIG. 2(C)) are set. Also, CPU5
If it is determined in step 105 that the wheel speed Vx is greater than the speed KV3, the fourth filter F4 is selected in step 107.
Set the filter coefficients (FIG. 2(d)).

CPtJ5 performs step 10 in step 108.
The wheel speed signal from the wheel speed sensor electromagnetic pickup 3 is filtered using the filter coefficients selected in 2,104,106,107.

The CPLI 5 determines from the filtering result in step 109 that it is a low-pass filter with a cut-off frequency of ω1 or less, and a cut-off frequency of ω1. ω2. ω3. The wheel speed vy after filtering using a notch filter of ω4°ω5 is determined. The CPU 5 performs the operations in steps 100 to 109 above for 5m.
Do this every S.

The results of noise removal in this way are shown in Figure 4 (a
) and (b). As shown in the figure, vy for VX
It can be seen that noise has been removed.

Then, the CPU 5 performs the above operation on the four wheels, detects the occurrence of slip by determining the wheel speed y of each wheel in step 109, and when it determines that sling 1 has occurred, suppresses the slip. The throttle valve 14 is driven by the motor 5 via the motor drive circuit 9.
Controls the opening degree.

In this way, in this embodiment, the engine 1 is controlled by the wheel speed sensor rotor 2 and the wheel speed sensor pickup 3.
10 wheel rotation speed of a vehicle equipped with 3 (wheel speed VX)
A digital filter (CPt, 1
5") is set according to the torque fluctuation of the engine 13 or to the noise frequency ω1 (low-pass filter, notch filter) during idling rotation, so the 1 to 1 torque pulsations of the engine 13 are [,′
: It is possible to reliably remove noise caused by Further, the rotational speed of the wheel 1 (wheel speed VX) is detected from the detection signal, and a digital filter (CPLJ) is applied according to the rotational speed VX.
5) Cutoff frequency ω2. ω3. ω4. Since ω5 (notch filter) is set (selected), noise caused by wheel eccentricity etc. can be reliably removed from the detection signal.

Note that this invention is not limited to the above embodiments,
In the above embodiment, filter coefficients are selected from four types and used, but the types of filter coefficients may be increased or decreased as necessary. Furthermore, the filter coefficients may be changed continuously.

[Effects of the Invention] As described in detail above, according to the present invention, an excellent effect is achieved in which noise can be reliably removed from the detection signal of the rotational speed detection means mixed with various noises.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the rest of a traction system according to an embodiment of the present invention, FIGS. 2(a) to (d) are Bode diagrams, and FIG. 3 is a flowchart for explaining the operation. Figure 4 (a>, (b) is a diagram showing the 4J processing results. 1 is a wheel, 2 is a rotor for a wheel speed sensor that constitutes a rotational speed detection means, and 3 is a wheel speed sensor that constitutes a rotational speed detection means. pickup, 4 (controller 1 to roller as filter and cutoff frequency setting means, 13 engine).

Claims (2)

[Claims] 1. A rotation speed detection means for detecting the rotation speed of a wheel of a vehicle equipped with an engine, a filter for inputting a detection signal of the rotation speed detection means and removing noise therein, and a cutoff frequency of the filter. A wheel speed signal processing device comprising cutoff frequency setting means for setting a frequency according to engine torque fluctuations. 2. a rotational speed detection means for detecting the rotational speed of a wheel of a vehicle; a filter for inputting a detection signal of the rotational speed detection means and removing noise therefrom; and an inputting of the detection signal of the rotational speed detection means. A wheel speed signal processing device comprising: cutoff frequency setting means for setting the cutoff frequency of the filter according to the rotational speed of the wheel.