JP2003124825A - Noise reduction device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a noise reduction device which can reduce noise of a high-frequency component included in an electric signal without delaying the phase. SOLUTION: This device is equipped with a phase leading compensation part E1 which generates a phase leading compensation signal T1 by advancing the phase of a steering torque signal (electric signal) T detected by a steering torque sensor 26 by a specific quantity, a differential value calculation part T2 which calculates a differential value signal T2 of the steering torque signal T, and a subtraction processing part E3 which subtracts the differential value signal T2 calculated by the differential value calculation part E2 from the phase leading compensation signal T1 whose phase is advanced by the specific quantity through the phase leading compensation part E1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a noise removing device for removing noise contained in a signal obtained by phase lead compensation of an electric signal such as a steering torque signal from a steering force sensor in an electric power steering system.

[0002]

2. Description of the Related Art As the above-mentioned signal containing noise, there is, for example, a phase lead compensation signal in an electric power steering apparatus disclosed in Japanese Patent Laid-Open No. 61-85271. That is, the electric power steering apparatus is provided with a phase lead compensator that issues a signal proportional to the differential value of the steering torque signal from the steering force sensor that detects the torsion torque (steering torque signal) of the steering shaft. The phase lead compensator is provided to compensate for the delay of the control system transfer characteristic caused by the friction of the steering system or the like from the steering torque signal. This has the effect of stabilizing the control system and canceling the delay due to the inertia of the power assist electric motor. This phase lead compensator is composed of an analog circuit or a digital circuit, and its frequency response characteristic is such that the gain and the phase lead are increased as the frequency of the steering torque signal is increased, compared to the case where no phase lead compensation is performed. Have the characteristics to

[0003]

However, since the phase lead compensator in the above conventional example takes the differential value of the steering torque signal, the steering torque signal compensated by the phase lead compensator is not included in the phase lead compensator. Since noise is easy to get in and the noise is amplified in the frequency region where the gain is increased in this phase advance compensator and becomes the current command value to the electric motor, if the gain of the phase advance compensator is high, this current command value There is a problem in that the output of the electric motor driven on the basis of the above includes the noise output. Therefore, if the gain of the phase lead compensation unit is set low,
Along with this, the amount of phase advance decreases, which causes a problem that the responsiveness of the control system in the electric power steering device deteriorates.

The present invention has been made in view of the above-mentioned conventional problems, and provides a noise eliminator capable of reducing the noise of high frequency components contained in an electric signal without delaying the phase. The purpose is to

[0005]

In order to achieve the above object, a noise removing device according to claim 1 of the present invention comprises a phase compensating means for advancing the phase of an electric signal by a predetermined amount, and a differential value of the electric signal. Means for calculating the differential value, and a subtraction processing means for subtracting the differential value calculated by the differential value calculating means from the electric signal whose phase is advanced by a predetermined amount by the phase compensating means. And

According to a second aspect of the present invention, there is provided the noise removing device according to the first aspect, wherein the plurality of differential value calculating means are provided and each differential value calculating means is differentially processed with different transfer characteristics. The subtraction processing means is configured to subtract the sum of the differential values calculated by the plurality of differential value calculating means from the electric signal formed by the phase compensating means.

According to a third aspect of the present invention, there is provided the noise elimination device according to the first or second aspect, wherein the electric signal is a steering torque signal in the electric power steering device.

[0008]

In the noise removing device according to claim 1 of the present invention,
As described above, in the subtraction processing means, from the electric signal whose phase is advanced by the predetermined amount in the phase compensating means, an electric signal (differential value) almost the same as the high frequency including many noise components calculated by the differential value calculating means is obtained. By performing the subtraction processing, it is possible to reduce the noise of the high frequency component included in the electric signal without delaying the phase.

As described above, the noise removing device according to the second aspect of the present invention combines a plurality of types of electrical signals (differential values) that have been differentially processed by the plurality of differential value calculating means with different transfer characteristics, respectively. Since an electric signal having a waveform (sum of differential values) can be obtained, it becomes possible to bring the electric signal closer to the high frequency component of the phase-compensated electric signal, and this electric signal (sum of differential values) is compensated for by the phase compensating means. By subtracting from the electrical signal formed by
The noise removal effect of high frequency components is improved.

As described above, the noise removing apparatus according to the third aspect of the present invention applies the steering torque signal as an electric signal to the electric power steering apparatus, thereby compensating the response delay to the steering input by the phase compensating means, and Since the noise of the high frequency component can be removed, the electric power steering device with good responsiveness can be obtained.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment of the Invention) First, the configuration of the first embodiment of the present invention will be described with reference to FIG.

FIG. 1 is a schematic configuration diagram of an electric power steering apparatus to which the noise removing apparatus according to the first embodiment of the present invention is applied. As shown in this figure, a steering wheel 20 as steering input means is connected. Steering shaft 21,
Rack and pinion 23, 24 provided on the output shaft 22 at the lower end of the steering shaft 21, a steering force sensor 26 provided on the lower end side of the output shaft 22 for detecting the steering torque of the steering wheel 20, and the rack. A hydraulic cylinder 27 connected to the hydraulic cylinder 23 and a hydraulic circuit 28 for supplying and discharging hydraulic pressure to and from the hydraulic cylinder 27 are provided.

In the hydraulic cylinder 27, a piston rod 30 connected to the rack penetrates through a cylindrical cylinder portion 29 extending in the width direction of the vehicle body, and the piston rod 30 has an internal cylindrical cylinder portion 29. A piston 31 that slides on is fixed. A left and right first hydraulic chamber 32 and a second hydraulic chamber 33 are separated by a piston 31 in the tubular cylinder portion 29. 25a and 25b are
The left and right front wheels are connected to both ends of the piston rod 30 via links.

The hydraulic circuit 28 has a pair of first and second communication passages 3 each having one end connected to the hydraulic chambers 32 and 33.
4, 35 and the other ends of the two communication passages 34, 35 are connected to each other and can be rotated forward and backward by an electric motor 36. The first and second hydraulic chambers 3 are selectively selected from a pair of discharge ports 35a, 35b.
One reversible pump 37 that supplies hydraulic pressure to 2, 33
And a reservoir 39 which is connected to the reversible pump 37 and stores hydraulic oil therein.

The reservoir 39 is adapted to supply and replenish the hydraulic oil stored therein to the reversible pump 37 via a supply passage 38, and at the same time, the reversible pump 37.
The leaked hydraulic oil is collected from each of the components.

The electric motor 36 is controlled to rotate in the forward and reverse directions by a control current output from the control unit ECU. The control unit ECU controls information such as a steering torque signal from the steering force sensor 26. The control current is output by calculation based on the signal.

Next, the contents of the electric motor drive control in this control unit ECU will be explained based on the control block diagram of FIG. First, in the phase advance compensator (phase compensator) E1, the phase advance compensation signal T1 (see FIG. 3) obtained by advancing the phase of the steering torque signal T (see (a) in FIG. 3) detected by the steering force sensor 26 by a predetermined amount. 3 (see (b)).

On the other hand, a differential value calculating section (differential value calculating means) E
In 2, the differential value signal T2 (see (C) of FIG. 3) of the steering torque signal T (see (A) of FIG. 3) detected by the steering force sensor 26 is calculated. Then, in the subtraction processing unit (subtraction processing means) E3, from the phase advance compensation signal T1 generated by the phase advance compensation unit E1 (see (b) in FIG. 3),
A corrected steering signal T3 (see (d) in FIG. 3) is calculated by subtracting the differential value T2 (see (c) in FIG. 3) calculated by the differential value calculation unit E2.

The current command calculation unit E4 performs a process for calculating the current command value I based on the corrected steering signal T3 calculated by the subtraction processing unit E3. This current command calculation unit E4
As shown schematically in the graph in the figure, is equipped with a memory for calculating the current command value I corresponding to the corrected steering signal T3 and a digital calculation circuit.

In the electric motor drive section E5, the electric motor 36 is driven based on the current command value I calculated by the current command calculation section E4. This electric motor drive unit E5
Is composed of a power MOS or the like, receives the current command value I which is the output of the current command calculation unit E4 as a voltage through a D / A converter (not shown), and drives and controls the electric motor 36.

Next, the content of the noise removal processing in the noise removal apparatus applied to the electric power steering apparatus according to Embodiment 1 of the present invention will be described based on the flowchart of FIG. First, in step S101, the steering torque signal T detected by the steering force sensor 26 is read,
In step S102, the phase lead compensator E1
Phase lead compensation is performed to generate a phase lead compensation signal T1 obtained by advancing the phase of the steering torque signal T by a predetermined amount.

In the following step S103, the differential value calculating section E2 calculates the differential value signal T2 by differentiating the steering torque signal T, and the step S104.
Then, in the subtraction processing section E3, the differential steering signal T3 is calculated by subtracting the differential value signal T2 from the phase advance compensation signal T1.

Finally, in step S105, the current command calculator E4 calculates the current command value I based on the corrected steering signal T3. Then, based on this current command value I, in the electric motor drive unit E5,
The drive control of the electric motor 36 will be performed.

Next, the operation and effect of the first embodiment of the present invention will be described. Originally, the phase lead compensator E1 is provided to compensate for the delay of the control system transfer characteristic caused by the friction of the steering system or the like from the steering torque signal T. The phase of the signal T is changed to stabilize the control system and cancel the delay due to the inertia of the power assist electric motor. The phase lead compensator E1 is composed of an analog circuit or a digital circuit, and its frequency response characteristic advances the phase of a predetermined frequency band of the steering torque signal T, and gain and gain more than in the case where no phase lead compensation is performed. It has the property of increasing the phase lead.

However, since the gain characteristic of the phase lead compensation signal T1 which is phase lead compensated by the phase lead compensator E1 has a high gain on the high frequency side, noise is amplified and the current command value I to the electric motor 36 is amplified. Therefore, the noise output is included in the output of the electric motor 36 driven based on the current command value I.

Therefore, in the first embodiment of the present invention, as described above, in the subtraction processing means E3, the differential value calculating part is calculated from the phase lead compensating signal T1 whose phase is advanced by the predetermined amount in the phase lead compensating part E1. By subtracting the differential value signal T2, which is almost the same as the high frequency including the noise component calculated in E2, the noise of the high frequency component included in the phase advance compensation signal T1 can be reduced without delaying the phase. The effect of becoming like this is obtained.

Further, in the first embodiment of the present invention, as described above, by applying the noise removing device to the electric power steering device using the steering torque signal T as an electric signal, the response delay to the steering input is compensated for the phase lead. Since the high-frequency component noise can be removed by the differential value calculation unit E2 and the subtraction processing unit E3 while being compensated by the unit E1, it is possible to obtain an electric power steering device with good responsiveness.

Next, another embodiment of the present invention will be described. In the description of the other embodiments of the present invention, the same components as those of the first embodiment of the present invention will not be illustrated and described, or will be denoted by the same reference numerals and the description thereof will be omitted, Only the points will be described.

(Embodiment 2 of the Invention) As shown in the block diagram of FIG. 5, the noise removing apparatus according to Embodiment 2 of the present invention is provided with a plurality of the differential value calculating sections E2 and each differential value is Calculation unit (first differential value calculation unit E2-1, second
Differential value calculating section E2-2) is configured to perform differential processing with different transfer characteristics, and in the newly added addition processing section E6, the first differential value calculating section E2-1 and the second differential value calculating section E2-1 The subtraction processing unit E3 calculates the sum of the differential value signals T2-1 and T2-2 calculated by the differential value calculating unit E2-2, and the subtraction processing unit E3 uses the phase lead compensating signal T1 formed by the phase lead compensating unit E1. It is configured to subtract the sum of both differential value signals T2-1 and T2-2 calculated by the first differential value calculating section E2-1 and the second differential value calculating section E2-2. 2, which is different from the first embodiment of the invention shown in FIG.

Next, the content of the noise removal processing in the noise removal apparatus applied to the electric power steering apparatus according to the second embodiment of the present invention will be described based on the flowchart of FIG. First, in step S201, the steering torque signal T detected by the steering force sensor 26 is read,
In step S202, the phase lead compensator E1
Phase lead compensation is performed to generate a phase lead compensation signal T1 obtained by advancing the phase of the steering torque signal T by a predetermined amount.

In a succeeding step S203, a differential value signal T2-1 is calculated by differentiating the steering torque signal T in a first differential value calculating section E2-1, and in a step S204, a second differential value is calculated. In the value calculation section E2-2,
A differential value signal T2-2 is calculated by differentiating the steering torque signal T.

In the following step S205, the addition processing unit E
6, the differential signal T calculated by the first differential value calculating unit E2-1 and the second differential value calculating unit E2-2, respectively.
2-1 and T2-2 are added to obtain addition differential value signals T2-1 and T2, and in the subsequent step S206, the subtraction processing unit E3 calculates the addition differential value signal T2 from the phase advance compensation signal T1.
-1 and 2 are subtracted to calculate the corrected steering signal T3.

Finally, in step S207, the current command calculation section E4 calculates the current command value I based on the corrected steering signal T3. Then, based on this current command value I, in the electric motor drive unit E5,
The drive control of the electric motor 36 will be performed.

In the noise removing device according to the second embodiment of the present invention, as described above, the first differential value calculating section E2-1.
And the second differential value calculating unit E2-2 is combined (added) with the differential value signals T2-1 and T2-2 which are differentially processed with different transfer characteristics, respectively, to thereby add differential value signal T2-- having a desired waveform. Since 1 and 2 can be obtained, it becomes possible to approach the high frequency component of the phase-lead compensation signal T1 that has been phase-compensated, and the added differential value signals T2-1 and 2
Is subtracted from the phase lead compensation signal T1 formed by the phase lead compensating means E1, the effect of improving the noise removal effect of high frequency components can be obtained.

Although the embodiments of the present invention have been described above with reference to the drawings, the specific configurations are not limited to the embodiments of the present invention, and there are design changes and the like within the scope not departing from the gist of the present invention. Also included in the present invention.

For example, in the embodiment of the invention, the example in which the noise removing device of the present invention is applied to the steering torque signal in the electric power steering device is shown. However, in addition to this, for example, a feedback signal in position control of a machine tool or the like. Can be applied to. In addition, the second embodiment of the invention
Then, two differential value calculation units are provided, but three or more differential value calculation units may be provided.

[0037]

As described above, the present invention claims 1.
In the noise removing device described above, as described above, the phase compensating means for advancing the phase of the electric signal by a predetermined amount, the differential value calculating means for calculating the differential value of the electric signal, and the phase compensating means for the predetermined amount of phase. And a subtraction processing unit that subtracts the differential value calculated by the differential value calculation unit from the advanced electric signal, the high frequency included in the electric signal without delaying the phase. The effect that the noise of the component can be reduced can be obtained.

According to a second aspect of the present invention, there is provided the noise elimination apparatus according to the first aspect, wherein a plurality of the differential value calculating means are provided and each differential value calculating means is differentially processed with different transfer characteristics. The subtraction processing means is configured to subtract the sum of the differential values calculated by the plurality of differential value calculating means from the electric signal formed by the phase compensating means. By combining a plurality of types of electrical signals (differential values) that have been differentiated with different transfer characteristics in the value calculating means, an electrical signal having a desired waveform (sum of differential values)
Therefore, it becomes possible to bring the phase-compensated electric signal closer to the high frequency component, and this electric signal (sum of differential values) is subtracted from the electric signal formed by the phase compensation means. As a result, it is possible to improve the noise removal effect of high frequency components.

According to a third aspect of the present invention, in the noise elimination apparatus according to the first aspect or the second aspect, the electric signal is a steering torque signal in the electric power steering apparatus. Since the delay can be compensated by the phase compensating means and the noise of the high frequency component can be removed, an electric power steering device with good responsiveness can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an electric power steering device to which a noise removing device according to a first embodiment of the invention is applied.

FIG. 2 is a control block diagram showing the contents of electric motor drive control in the noise elimination device according to the first embodiment of the invention.

FIG. 3 is a time chart showing each signal in the noise eliminator of the first embodiment of the invention.

FIG. 4 is a flowchart showing the content of noise removal processing in the noise removal device according to the first embodiment of the invention.

FIG. 5 is a control block diagram showing the contents of electric motor drive control in the noise removal device according to the second embodiment of the invention.

FIG. 6 is a flowchart showing the content of noise removal processing in the noise removal device according to the second embodiment of the invention.

[Explanation of symbols]

20 steering wheel 21 Steering axis 22 Output shaft 23 racks 24 pinion 25a left front wheel 25b right front wheel 26 Steering force sensor 27 hydraulic cylinder 28 Hydraulic circuit 29 Cylindrical cylinder 30 piston rod 31 pistons 32 First hydraulic chamber 33 Second hydraulic chamber 34 First communication passage 35 Second communication passage 36 electric motor 37 Reversible pump 38 supply path 39 Reservoir ECU control unit

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Claims (3)

[Claims] 1. A phase compensating unit that advances the phase of an electric signal by a predetermined amount, a differential value calculating unit that calculates a differential value of the electric signal, and an electric signal whose phase is advanced by the predetermined amount by the phase compensating unit. A subtraction processing unit that performs a subtraction process on the differential value calculated by the differential value calculation unit. 2. A plurality of said differential value calculating means are provided, each differential value calculating means is differentially processed with different transfer characteristics, and said subtraction processing means is provided with said plurality of differential signals from the electric signal formed by said phase compensating means. The noise removing device according to claim 1, wherein the noise removing device is configured to subtract the sum of the differential values calculated by the differential value calculating means. 3. The noise eliminator according to claim 1, wherein the electric signal is a steering torque signal in an electric power steering device.