WO2024053013A1

WO2024053013A1 - Noise removal circuit and sensor

Info

Publication number: WO2024053013A1
Application number: PCT/JP2022/033559
Authority: WO
Inventors: 祐也立岡
Original assignee: ファナック株式会社
Priority date: 2022-09-07
Filing date: 2022-09-07
Publication date: 2024-03-14

Abstract

This noise removal circuit that removes the effect of noise from the data output from a sensor circuit comprises: a conductor wire that surrounds an electric cable; a noise detection circuit for generating a noise detection signal indicating the presence or absence of noise in the electric cable on the basis of the electric signal generated in the conductor wire; and a data processing circuit that invalidates data output from the sensor circuit during an invalidation period that includes at least a period in which the noise detection signal indicates that noise has occurred.

Description

Noise removal circuit and sensor

The present invention relates to a noise removal circuit and a sensor.

The motor used to drive the arm of the robot is supplied with driving power by an inverter. The inverter is controlled based on a PWM (Pulse Width Modulation) signal. Wiring that supplies PWM-controlled motor drive power becomes a source of noise.

For example, an AE measurement device that measures AE generated from an object to be measured includes a measurement AE sensor that detects an AE signal generated from the object to be measured, and an external AE signal generated outside the object to be measured. an AE sensor for external noise to detect; a determination unit that determines whether or not there is external noise based on an external AE signal detected by the AE sensor for external noise; and an AE signal detected by the AE sensor for measurement. Sometimes, an AE measurement device is known that includes a measurement processing section that validates the AE signal when the determination section determines that there is no external noise (for example, see Patent Document 1).

For example, a plurality of coils are connected continuously along one closed line, and a connection is made parallel to the closed line from the end of the last coil of the plurality of coils to the start of winding of the first coil. A Rogoski that has a line and detects the voltage induced between the winding start side terminal of the first coil and the terminal of the return line as a function of the current of the circuit under test inserted inside the closed line. In the type current sensor, each coil constituting the plurality of coils is formed on a plane perpendicular to the closed line, and the distance between the end of one coil and the start of the next coil among the adjacent coils is A Rogowski type current sensor is known, which is connected by an outgoing line parallel to the closed line, and characterized in that the entire outgoing line and the incoming line are disposed close to each other (for example, Patent Document (See 2).

Japanese Patent Application Publication No. 2010-71945 International Publication No. 2017/014297

Noise caused by motor drive power has a negative effect on the accuracy of various sensors and the control of various devices. Therefore, it is extremely important to detect noise and remove its effects. For example, a robot arm is provided with a torque sensor for detecting torque, and noise caused by motor drive power adversely affects the accuracy of the torque sensor. An object of the present disclosure is to realize a noise removal circuit that removes the influence of noise from data output from a sensor circuit, and a sensor equipped with the noise removal circuit.

According to one aspect of the present disclosure, a noise removal circuit that removes the influence of noise from data output from a sensor circuit uses a conductor wire that surrounds an electric cable and an electric signal generated in the conductor wire. Among data output from a noise detection circuit that generates a noise detection signal indicating the presence or absence of noise generation in the cable and a sensor circuit, data during an invalidation period that includes at least a period in which the noise detection signal indicates the presence of noise generation is invalidated. and a data processing circuit.

Further, according to one aspect of the present disclosure, the sensor includes a sensor circuit that outputs data that is a sensor detection result about a target object, and the noise removal circuit that removes the influence of noise from the data output from the sensor circuit. , a substrate having an opening through which an electric cable passes, and a conductor wire is routed so as to surround the opening.

According to one aspect of the present disclosure, it is possible to realize a noise removal circuit that removes the influence of noise from data output from a sensor circuit, and a sensor equipped with the same.

1 is a diagram showing a noise removal circuit and a torque sensor including the same according to an embodiment of the present disclosure. FIG. 1 is a diagram illustrating a robot with a torque sensor according to an embodiment of the present disclosure. FIG. FIG. 3 is a diagram illustrating noise generated due to motor drive power flowing through an electric cable. FIG. 2 is a perspective view showing a substrate according to a first form of a torque sensor according to an embodiment of the present disclosure. FIG. 3 is a perspective view showing a substrate according to a second form of a torque sensor according to an embodiment of the present disclosure. FIG. 7 is a perspective view showing a substrate according to a third form of a torque sensor according to an embodiment of the present disclosure. FIG. 2 is a circuit diagram showing a configuration of a noise detection circuit in a noise removal circuit according to an embodiment of the present disclosure. FIG. 3 is a waveform diagram illustrating a function of a noise detection circuit in a noise removal circuit according to an embodiment of the present disclosure. FIG. 2 is a waveform diagram illustrating a noise detection signal generated by a noise detection circuit in a noise removal circuit according to an embodiment of the present disclosure. FIG. 2 is a waveform diagram (part 1) illustrating filter settings by the noise detection circuit in the noise removal circuit according to the embodiment of the present disclosure. FIG. 7 is a waveform diagram (part 2) illustrating filter settings by the noise detection circuit in the noise removal circuit according to the embodiment of the present disclosure. FIG. 3 is a waveform diagram illustrating the relationship between noise and invalidation period data in the embodiment of the present disclosure. FIG. 3 is a waveform diagram showing data invalidation processing by the first form of the data processing circuit in the noise removal circuit according to the embodiment of the present disclosure. FIG. 7 is a waveform diagram showing data invalidation processing by a second form of the data processing circuit in the noise removal circuit according to the embodiment of the present disclosure.

Hereinafter, a noise removal circuit and a torque sensor according to an embodiment will be described with reference to the drawings. In addition, in the following description, the same code|symbol is attached to the structure which has the same or similar function. Redundant explanations of these configurations may be omitted. Furthermore, in the following description, "connected" means "electrically connected".

<Overall configuration of noise removal circuit and torque sensor>
FIG. 1 is a diagram showing a noise removal circuit and a torque sensor including the same according to an embodiment of the present disclosure. Further, FIG. 2 is a diagram illustrating a robot equipped with a torque sensor according to an embodiment of the present disclosure.

According to the embodiment of the present disclosure, the torque sensor 100 includes a noise removal circuit 1, a sensor circuit 2, and a substrate 3 (not shown in FIG. 1). In this embodiment, as an example, the sensor circuit 2 is provided in a torque sensor 100 that detects the torque of a target object 300. As a modification of this example, the sensor circuit 2 may be provided in a sensor other than the torque sensor. For example, the sensor circuit 2 may be a current sensor, voltage sensor, magnetic sensor, speed sensor, temperature sensor, or the like, which outputs electrical sensor data.

The torque sensor 100 is provided within the arm of the robot 1000, for example. The substrate 3 of the torque sensor 100 is provided with a noise removal circuit 1, a sensor circuit 2, and the like.

The sensor circuit 2 outputs data (hereinafter referred to as "sensor data") that is the sensor detection result for the object 300. Here, since a torque sensor is used as an example, the sensor circuit 2 outputs sensor data regarding the torque detected on the object 300. The object 300 that is the target of torque detection is a motor that drives an arm of a robot. The sensor data output by the sensor circuit 2 may be analog data (analog signal) or digital data (digital signal).

The noise removal circuit 1 removes the influence of noise from the sensor data output from the sensor circuit 2. The noise removal circuit 1 includes a conductive wire 11, a noise detection circuit 12, and a data processing circuit 13.

The substrate 3 of the torque sensor 100 is provided with an opening. An electric cable 200 through which PWM-controlled motor drive power flows is arranged so as to pass through the opening. The conductive wire 11 is wired so as to surround the opening on the substrate. Therefore, the conducting wire 11 is wired so as to surround the electric cable 200, which is a source of noise caused by motor drive power.

The noise detection circuit 12 generates a noise detection signal indicating the presence or absence of noise in the electric cable 200 based on the electric signal generated in the conductive wire 11. Details of the noise detection process by the noise detection circuit 12 will be described later.

Of the sensor data output from the sensor circuit 2, the data processing circuit 13 invalidates sensor data during an invalidation period that includes at least a period in which the noise detection signal indicates that noise has occurred. Details of the data invalidation process by the data processing circuit 13 will be described later.

A processing unit (processor) is provided within the torque sensor 100. Examples of arithmetic processing devices include ICs, LSIs, CPUs, MPUs, and DSPs. The data processing circuit 13 may be composed of only an arithmetic processing device, or may be composed of a combination of an analog circuit and an arithmetic processing device, or may be composed only of an analog circuit. For example, when the data processing circuit 13 is constructed in the form of a software program, the functions of the data processing circuit 13 can be realized by operating the arithmetic processing device according to this software program. Alternatively, the data processing circuit 13 may be implemented as a semiconductor integrated circuit written with a software program that implements the functions of the data processing circuit 13. Alternatively, the data processing circuit 13 may be implemented as a recording medium on which a software program for realizing the functions is written.

Note that the conducting wire 11 and the noise detection circuit 12 may be replaced with a Rogowski coil type current detection circuit. In this case, the data processing circuit 13 is connected to the Rogowski coil type current detection circuit, and the electric cable 200 is arranged so as to penetrate through the opening of the substrate where the Rogowski coil is provided.

<Principle of noise generation due to motor drive power>
FIG. 3 is a diagram illustrating noise generated due to motor drive power flowing through an electric cable.

Wiring that supplies PWM-controlled motor drive power becomes a source of noise. The motor drive power flowing through the electric cable 200 is a rectangular wave voltage, and according to the change of the rectangular wave voltage between High and Low, a minute change in the magnetic field occurs around the electric cable 200, and the magnetic field near the electric cable 200 is generated. Noise occurs in the sensor data output from the sensor circuit 2. For example, as shown in FIG. 3, at time t ₂ when the motor drive power switches from Low to High and time t ₄ when the motor drive power switches from High to Low, a magnetic field exists around the electric cable 200 through which the motor drive power flows. Minute changes occur. As a result, noise occurs in the sensor data output from the sensor circuit 2 near the electric cable 200 at times t ₂ and t ₄ .

Therefore, in the embodiment of the present disclosure, the conducting wire 11 is wired to surround the electric cable 200 in order to detect changes in the magnetic field around the electric cable 200 through which motor drive power flows. Noise is generated in the conducting wire 11 in response to changes in the motor drive power flowing through the electric cable 200. The noise detection circuit 12 generates a noise detection signal indicating the presence or absence of noise generation in the electric cable 200 based on the electric signal related to the noise generated in the conductive wire 11.

<Structure of the noise removal circuit board>
The substrate of the torque sensor 100 provided on the arm of the robot 1000 may be provided with openings for passing various cables. An electrical cable 200 through which motor drive power flows is also placed through the opening in the board. Therefore, in the embodiment of the present disclosure, the conducting wire 11 is wired so as to surround the opening of the substrate 3 of the torque sensor 100, so that the conducting wire 11 surrounds the electric cable 200. In addition, as a modification of this example, an opening is provided in the housing of the torque sensor 100, the conducting wire 11 is wired so as to surround the opening in the housing of the torque sensor 100, and the electric cable 200 is placed through the opening. In this way, the conductive wire 11 may surround the electric cable 200.

Hereinafter, some examples of the form of the substrate will be listed.

FIG. 4 is a perspective view showing a substrate according to a first form of a torque sensor according to an embodiment of the present disclosure.

The substrate 3 according to the first embodiment has an annular shape with an opening 31 provided near the center of the disk-shaped substrate. An electrical cable 200 passes through the opening 31. On the substrate 3, a conductive wire 11 wired to surround the opening 31, a noise detection circuit 12, and a data processing circuit 13 are provided.

FIG. 5 is a perspective view showing a substrate according to a second form of a torque sensor according to an embodiment of the present disclosure.

The substrate 3 according to the second embodiment has a shape in which an opening 31 is provided near the center of a C-shaped substrate having a notch in a part in the circumferential direction. An electrical cable 200 passes through the opening 31. On the substrate 3, a conductive wire 11 wired in a C shape so as to surround a part of the opening 31, a noise detection circuit 12, and a data processing circuit 13 are provided.

FIG. 6 is a perspective view showing a substrate according to a third form of a torque sensor according to an embodiment of the present disclosure.

The substrate 3 according to the third embodiment has a shape in which an opening 31 is provided near the center of a substantially rectangular substrate. An electrical cable 200 passes through the opening 31. On the substrate 3, a conductive wire 11 wired in a substantially rectangular shape so as to surround the opening 31, a noise detection circuit 12, and a data processing circuit 13 are provided.

The first to third embodiments described above are just examples, and as long as the board is wired so that the conductive wire 11 surrounds the opening 31 through which the electric cable 200 passes, the board shape and wiring shape other than those shown in the drawings may be used. You may do so.

<Example of configuration of noise detection circuit>
FIG. 7 is a circuit diagram showing a configuration of a noise detection circuit in a noise removal circuit according to an embodiment of the present disclosure.

As described above, the noise detection circuit 12 is connected to the conducting wire 11 and the data processing circuit 13. A strain gauge whose resistance value changes depending on the torque applied to the motor is connected to terminals P1 and P2 of the sensor circuit 2.

The noise detection circuit 12 includes a DC component adjustment section 21, a threshold value setting section 22, a comparison section 23, a wired OR connection section 24, a filter 25, and a buffer 26.

The DC component adjustment section 21 includes a capacitor 21-1 that removes a DC component from the electrical signal generated in the conductor 11, and resistors 21-2 and 21-3 that apply a specified DC component. In the DC component adjustment section 21, the DC component is removed from the electrical signal generated in the conductor 11 by the capacitor 21-1, and a predetermined DC component is applied again using the resistors 21-2 and 21-3. The resistors 21-2 and 21-3 set the reference voltage when there is no noise between the upper and lower thresholds set by the threshold setting unit 22 (hereinafter sometimes referred to as "threshold range"). ).

The threshold setting section 22, the comparison section 23, the wired OR connection section 24, the filter 25, and the buffer 26 constitute a noise detection signal generation section.

The threshold value setting unit 22 is provided to set a threshold value for detecting noise from the electrical signal generated in the conductive wire 11. The noise contained in the electrical signal generated in the conductive wire 11 is an oscillatory signal having a positive amplitude and a negative amplitude. In order to detect this noise, an upper threshold value used for comparison with the positive amplitude of the electrical signal and a lower threshold value used for comparison with the negative amplitude of the electrical signal are set by the threshold setting unit 22. . The upper threshold value is input to the inverting input (-) of the first comparator 23-1 that constitutes the comparison section 23. The lower threshold value is input to the non-inverting input (+) of the second comparator 23-2 forming the comparing section 23.

The comparison unit 23 compares a threshold consisting of an upper threshold and a lower threshold with the electrical signal whose DC component has been adjusted by the DC component adjustment unit 21. For this reason, the comparison section 23 includes a first comparator 23-1 and a second comparator 23-2.

The non-inverting input (+) of the first comparator 23-1 receives an electrical signal whose DC component has been adjusted by the DC component adjustment unit 21, and the inverting input (-) receives the upper threshold value. The first comparator 23-1 can detect whether the positive amplitude of the electrical signal whose DC component has been adjusted by the DC component adjustment section 21 exceeds the upper threshold value. Further, the inverting input (-) of the second comparator 23-2 receives an electrical signal whose DC component has been adjusted by the DC component adjusting section 21, and the non-inverting input (+) receives the lower threshold value. be done. The second comparator 23-2 can detect whether the negative amplitude of the electrical signal whose DC component has been adjusted by the DC component adjustment section 21 has fallen below the lower threshold.

The signal output from the comparison section 23 (first comparator 23-1 and second comparator 22-2) is input to the wired OR connection section 24. The wired OR connection unit 24 connects a signal that is output when the first comparator 23-1 determines that the positive amplitude of the electrical signal exceeds the upper threshold, and a signal that is output when the positive amplitude of the electrical signal is determined to be above the upper threshold by the second comparator 23-2. It is provided to perform a logical sum (OR) with a signal that is output when it is determined that the amplitude of is below the lower threshold value. Due to the presence of the wired OR connection section 24, when the first comparator 23-1 determines that the positive amplitude of the electrical signal exceeds the upper threshold, the second comparator 23-2 determines that the negative amplitude of the electrical signal exceeds the upper threshold. Noise generation can be detected regardless of which one of the cases where it is determined that the noise level has fallen below the lower threshold value occurs first.

The comparison section 23 and the wired OR connection section 24 are configured by, for example, a reset IC.

The filter 25 and the buffer 26 have the function of suppressing fluctuations in the presence or absence of noise that may occur as a result of generating a noise detection signal based on comparison with a threshold value, and increasing noise detection accuracy.

For example, by having the above-described configuration, the noise detection circuit 12 detects the electrical signal generated in the conducting wire 11 when it is determined that the electrical signal generated in the conducting wire 11 is larger than the upper threshold value or smaller than the lower threshold value. is outside a threshold range between the upper and lower thresholds, a noise detection signal indicating the presence of noise is generated and output. Further, the noise detection circuit 12 detects that when it is determined that the electrical signal generated in the conducting wire 11 is smaller than the upper threshold value and larger than the lower threshold value, that is, the electrical signal generated in the conducting wire 11 is determined to be equal to the upper threshold value and the lower threshold value. If the value falls within a certain threshold range, a noise detection signal indicating that no noise is generated is generated and output. For example, the noise detection signal indicates Low when indicating that noise has occurred, and indicates High when indicating that no noise has occurred. The noise detection signal generated by the noise detection circuit 12 as described above is input to the data processing circuit 13.

<Functions of noise detection circuit>
FIG. 8 is a waveform diagram illustrating the function of the noise detection circuit in the noise removal circuit according to the embodiment of the present disclosure. In FIG. 8, sampling points by the data processing circuit 13 for sensor data output from the sensor circuit 2 of the torque sensor 100 are indicated by black circles. That is, the data processing circuit 13 samples the sensor data output from the sensor circuit 2 at time _t5 , time _t6 , time _t7 , time _t8 , time _t9 , time _t10 , and time _t11 . .

If the torque sensor 100 is located near the electric cable 200 through which motor drive power flows, noise will occur in the sensor data output from the sensor circuit 2 of the torque sensor 100. In the example shown in FIG. 8, as an example, noise occurs at time _t7 and time _t9 . If we try to directly detect noise by directly monitoring the sensor data output from the sensor circuit 2, the magnitude of the sensor data containing noise at times _t7 and _t9 will be the same as the magnitude of the sensor data containing no noise at time t. ₆ (maximum value) and the sensor data at time _t10 (minimum value) that does not include noise. For this reason, there is a possibility that sensor data containing noise cannot be accurately distinguished from normal sensor data containing no noise. In contrast, in the embodiment of the present disclosure, only noise is detected by the noise detection circuit 12 based on the electrical signal generated in the conductive wire 11 wired so as to surround the electrical cable 200 (see the waveform diagram at the bottom of FIG. 8). ), noise can be detected accurately.

FIG. 9 is a waveform diagram illustrating a noise detection signal generated by the noise detection circuit in the noise removal circuit according to the embodiment of the present disclosure.

When the electrical signal generated in the conducting wire 11 (in FIG. 7, the electrical signal whose DC component has been adjusted by the DC component adjustment section 21) is out of the threshold range, the noise detection circuit 12 generates a noise detection signal indicating that noise has occurred. . In the example shown in FIG. 9, the electrical signal input to the noise detection circuit ₁₂ (that is, the electrical signal generated in the conducting wire 11) at time t12 exceeds the upper threshold. Therefore, the noise detection circuit 12 outputs a noise detection signal (Low) indicating that noise has occurred between time _t12 and time _t13 when a predetermined period has elapsed, and during the rest of the time, no noise is generated. A noise detection signal (High) indicating this is output. Since the arrangement of the inverter circuit and electric cable 200 that electrically affect the torque sensor 100 provided in the robot 1000 has not changed much since the robot was manufactured, the noise contained in the electric signal generated in the conductor 11 is reproducible. Therefore, the time required for the noise to subside after it occurs is also approximately constant. Therefore, in the embodiment of the present disclosure, during the development of the robot 1000, etc., the time required for the noise to subside after the noise occurs is measured in advance, and based on the measured time, the noise is determined to be generated. Set the time required for the noise to subside. The constant of the filter 25 is determined based on this set time.

FIGS. 10 and 11 are waveform diagrams illustrating filter settings by the noise detection circuit in the noise removal circuit according to the embodiment of the present disclosure.

As shown in FIG. 10, when the constant of the filter 25 is set to a weak value, the electrical signal input to the noise detection circuit 12 (that is, the electrical signal generated in the conductive wire 11) reaches the upper threshold and the lower threshold in a short period of time. The magnitude relationship with the threshold value is reversed. Therefore, "flapping of the noise detection signal" occurs in which the noise detection signal (Low) indicating the presence of noise generation and the noise detection signal (High) indicating the absence of noise generation are switched in a short period of time.

As shown in FIG. 11, when the constant of the filter 25 is set to be strong, the occurrence of noise is detected when the electrical signal input to the noise detection circuit 12 (that is, the electrical signal generated in the conductive wire 11) exceeds the upper threshold. The time from time t ₁₂ at which the noise detection signal (Low) indicating the occurrence of noise is output to time t ₁₅ at which the noise detection signal (High) indicating no noise is output becomes longer. As a result, even data in areas where there is no noise is unnecessarily invalidated.

Therefore, in the embodiment of the present disclosure, during the development of the robot 1000, etc., the time required for the noise to subside after the noise occurs is measured in advance, and based on the measured time, the noise is determined to be generated. The time required for the noise to subside is set, and an appropriate constant of the filter 25 is determined based on this set time.

FIG. 12 is a waveform diagram illustrating the relationship between noise and invalidation period data in the embodiment of the present disclosure.

As described with reference to FIG. 9, time _t12 , which is the point in time when the electrical signal generated in the conducting wire 11 deviates from the threshold range, is the starting point of the noise detection signal (Low) indicating the presence of noise. However, in reality, noise that does not exceed the threshold has been generated before time _t12 , which is the starting point of the noise detection signal. As described above, the noise contained in the electrical signal generated in the conductive wire 11 has reproducibility. Therefore, in the embodiment of the present disclosure, during the development of the robot 1000, etc., the electrical signal is set to the threshold value after the noise is generated. The time required for exceeding the threshold is measured in advance, and based on the measured time, a point in time that is a predetermined time before the start point of the noise detection signal (Low) indicating the presence of noise is detected in the sensor data. Set to the starting point of the invalidation period. In the example shown in FIG. 12, time ₁₄ , which is before time _t12 , which is the start point of the noise detection signal (Low) indicating the presence of noise, is set as the start point of the sensor data invalidation period. Note that it is necessary to invalidate the sensor data going back to time t ₁₄ , which is before time t ₁₂ , which is the starting point of the noise detection signal (Low) indicating the presence of noise. Therefore, the sensor data output from the sensor circuit 2 is temporarily held in a storage section (not shown) in the noise removal circuit 1, and the data processing circuit 13 is Then, a process is executed to invalidate the sensor data during the invalidation period.

Note that in order to simplify the configuration and processing within the noise removal circuit 1, time _t12 , which is the starting point of the noise detection signal (Low) indicating the presence of noise, is the starting point of the sensor data invalidation period. It may be set to In this case, the storage unit can be omitted since there is no need to temporarily hold sensor data.

<Data invalidation processing by data processing circuit>
Of the sensor data output from the sensor circuit 2, the data processing circuit 13 invalidates sensor data during an invalidation period that includes at least a period in which the noise detection signal indicates that noise has occurred. Below, some data invalidation processing by the data processing circuit will be listed.

FIG. 13 is a waveform diagram showing data invalidation processing by the first form of the data processing circuit in the noise removal circuit according to the embodiment of the present disclosure. In the example shown in FIG. 13, as an example, the starting point of the noise detection signal (Low) indicating the presence of noise is set to the starting point of the sensor data invalidation period. Note that the data processing circuit 13 may set the start point of the sensor data invalidation period to a point that is a predetermined time earlier than the start point of the noise detection signal (Low) indicating the presence of noise.

In the data invalidation process according to the first form, the data processing circuit 13 outputs the data output from the sensor circuit 2 as is during a period other than the invalidation period, and the data output from the sensor circuit 2 during the invalidation period. Stop outputting data. In the example shown in FIG. 13, the noise detection signal (Low) indicating that noise has occurred is output from the noise detection circuit 12 between time _{t 17} _and _time t ₁₈ . During the invalidation period, the output of the data output from the sensor circuit 2 is stopped, and during periods other than the invalidation period, the data output from the sensor circuit 2 is output as is. According to the data invalidation process according to the first embodiment, the influence of noise can be removed from sensor data.

FIG. 14 is a waveform diagram showing data invalidation processing by the second form of the data processing circuit in the noise removal circuit according to the embodiment of the present disclosure. In FIG. 14, sampling points by the data processing circuit 13 for sensor data output from the sensor circuit 2 are represented by S ₁ to S ₁₂ . In the example shown in FIG. 14, as an example, the starting point of the noise detection signal (Low) indicating the presence of noise is set to the starting point of the sensor data invalidation period. Note that the data processing circuit 13 may set the start point of the sensor data invalidation period to a point that is a predetermined time earlier than the start point of the noise detection signal (Low) indicating the presence of noise.

In the data invalidation process according to the second form, the data processing circuit 13 invalidates the sensor data during the invalidation period among the sensor data output from the sensor circuit 2, and then disables the sensor data during a predetermined period including the invalidation period. The values indicated by the sensor data output from the sensor circuit 2 are averaged and output. In _the example shown in FIG _. ₁₄ , sampling points _{S 3} _, _S ₇ _, S Disable sensor data in ₁₁ . Then, the values indicated by the sensor data at the sampling points S ₁ , S ₂ , S ₄ , S ₅ , S ₆ , S ₈ , S ₉ , S ₁₀ and S ₁₂ during the period other than the invalidation period are averaged and output. . The time period for averaging can be set arbitrarily. For example, when the sensor data output from the sensor circuit 2 is an analog signal, variations may occur in the values indicated by the sensor data due to thermal noise, etc. However, according to the data invalidation process according to the second form, the sensor It is possible to more reliably remove the influence of noise from data and generate highly accurate sensor data regarding torque.

As described above, according to the embodiment of the present disclosure, the conductor 11 is wired around the electric cable 200 that is a noise generation source, noise is detected based on the electric signal generated in the conductor 11, and the noise is detected from the sensor circuit 2. The data portion affected by noise among the output sensor data is invalidated. With such a configuration, abnormal values affected by noise can be accurately removed from the sensor data output from the torque sensor 100 (sensor circuit 2 thereof), so highly accurate sensor data regarding torque can be extracted. can be generated.

Generally, PWM-controlled motor drive power is switched between High and Low at high speed, so sensor data from torque sensors around the electric cable through which the motor drive power flows is easily affected by noise. For example, measures have been taken in the past to reduce the effects of noise by taking a time average of sensor data, but this poses a problem in that the high speed of sensor processing is lost. In contrast, according to the embodiment of the present disclosure, the data portion affected by noise among the sensor data output from the sensor circuit 2 is invalidated, so that high-speed sensor processing can be ensured.

In addition, if you try to directly detect noise by monitoring the sensor data output from the sensor circuit, the size of the sensor data that includes noise will be the maximum value of the sensor data that does not include noise, and the size of the sensor data that includes noise. It falls between the minimum value of the sensor data and the minimum value of the sensor data. For this reason, there is a possibility that it may not be possible to accurately distinguish between sensor data containing noise and normal sensor data containing no noise. In contrast, in the embodiment of the present disclosure, only noise is detected by the noise detection circuit 12 based on the electric signal generated in the conductor 11 wired so as to surround the electric cable 200, so that it is difficult to accurately detect noise. Can be done.

Furthermore, the substrate of the torque sensor 100 provided on the arm of the robot may be provided with an opening for passing various cables through. The embodiment of the present disclosure has a structure in which the conductive wire 11 is wired so as to surround the opening of the substrate 3 of the torque sensor 100, so that a noise removal circuit can be easily implemented even in a conventional torque sensor.

In the embodiment described above, the noise detection signal indicates Low when indicating the presence of noise generation, and indicates High when indicating the absence of noise generation. As an alternative example, the noise detection signal may be High when indicating that noise has occurred, and Low when indicating that no noise has occurred.

Furthermore, in the embodiment described above, the electric cable 200 is a power cable through which motor drive power flows. As a modification of this example, the electric cable 200 may be a cable other than a power cable through which motor drive power flows. For example, the electric cable 200 may be a signal cable through which a PWM signal used to control an inverter flows, or a power cable through which power supply power flows.

Furthermore, in the embodiment described above, the sensor circuit 2 is provided in the torque sensor 100 that detects the torque of the target object 300. As a modification of this example, the sensor circuit 2 may be provided in a sensor other than the torque sensor. For example, the sensor circuit 2 may be a current sensor, voltage sensor, magnetic sensor, speed sensor, temperature sensor, or the like, which outputs electrical sensor data.

Although the embodiments of the present disclosure have been described in detail, the present disclosure is not limited to the individual embodiments described above. These embodiments are subject to various additions, substitutions, and changes without departing from the gist of the invention or without departing from the gist of the present invention derived from the content described in the claims and equivalents thereof. , partial deletion, etc. are possible. For example, in the embodiments described above, the order of each operation and the order of each process are shown as examples, and are not limited to these. Further, the same applies when numerical values or formulas are used in the description of the embodiments described above.

1 Noise removal circuit 2 Sensor circuit 3 Board 11 Conductive wire 12 Noise detection circuit 13 Data processing circuit 21 DC component adjustment section 21-1 Capacitor 21-2, 21-3 Resistor 22 Threshold value setting section 23 Comparison section 23-1 First comparator 23-2 Second comparator 24 Wired OR connection 25 Filter 26 Buffer 31 Opening 100 Torque sensor 200 Electric cable 300 Object 1000 Robot

Claims

A noise removal circuit that removes the influence of noise from data output from a sensor circuit,
A conductor wire that surrounds an electric cable,
a noise detection circuit that generates a noise detection signal indicating the presence or absence of noise in the electric cable based on the electric signal generated in the conductor;
a data processing circuit that invalidates data output from the sensor circuit during an invalidation period that includes at least a period in which the noise detection signal indicates that noise has occurred;
A noise removal circuit.
The data processing circuit outputs the data output from the sensor circuit as is during a period other than the invalidation period, and stops outputting the data output from the sensor circuit during the invalidation period. 1. The noise removal circuit according to 1.
The data processing circuit invalidates the data output from the sensor circuit during the invalidation period, and then calculates a value indicated by the data output from the sensor circuit during a predetermined period including the invalidation period. 2. The noise removal circuit according to claim 1, wherein the noise removal circuit averages and outputs the averaged value.
The noise removal according to any one of claims 1 to 3, wherein a point in time that is a predetermined time before a period in which the noise detection signal indicates that noise has occurred is set as a starting point of the invalidation period. circuit.
The noise detection circuit includes:
a DC component adjustment unit that adjusts a DC component from the electrical signal generated in the conductor;
Noise detection that generates and outputs the noise detection signal indicating the presence of noise when it is determined that the amplitude of the electrical signal whose DC component has been adjusted by the DC component adjustment section is out of a predefined threshold range. a signal generation section;
The noise removal circuit according to any one of claims 1 to 4, comprising:
a sensor circuit that outputs data that is a sensor detection result about a target object;
The noise removal circuit according to any one of claims 1 to 5, which removes the influence of noise from the data output from the sensor circuit;
a substrate having an opening through which the electric cable passes, and on which the conductive wire is routed so as to surround the opening;
A sensor.
The sensor according to claim 6, wherein the sensor circuit and the noise removal circuit are provided on the substrate.