sensors that output data with reduced noise

Abstract

A sensor includes a substrate having an opening portion through which a power cable passes, a sensor circuit mounted to the substrate and outputting a sensor signal in an analog signal form as a sensor detection result regarding an object, a lead wire routed to the substrate in a manner of surrounding the opening portion, and a processing circuit mounted to the substrate and generating a noise-reduced signal in an analog signal form based on a difference between the sensor signal and a noise signal that is an electric signal generated in the lead wire.

Description

Technical Field

[0001] This disclosure relates to sensors that output data with reduced noise. Background Technology

[0002] The electric motors used to drive robot arms and machine tools are powered by inverters. The inverters are controlled based on pulse width modulation (PWM) signals. The wiring supplying power to the PWM-controlled motors becomes a source of noise.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2011-176534

[0006] Patent Document 2: Japanese Patent Application Publication No. 2014-055839

[0007] Patent Document 3: Japanese Patent Application Publication No. 2008-116782

[0008] Patent Document 4: Japanese Patent Application Publication No. 2017-034568

[0009] Patent Document 5: Japanese Patent Application Publication No. 2003-050254 Summary of the Invention

[0010] The problem that the invention aims to solve

[0011] Noise generated by the electric motor's power supply negatively impacts the accuracy of various sensors and the control of various devices. For example, torque sensors used to detect torque are installed in some robot arms, and the noise generated by the electric motor's power supply adversely affects the accuracy of these sensors. Therefore, it is desirable to accurately detect noise to reduce its impact on sensor output.

[0012] Methods for solving problems

[0013] According to one aspect of this disclosure, the sensor comprises: a substrate having an opening through which a cable passes; a sensor circuit mounted on the substrate that outputs a sensor signal in the form of an analog signal as a sensor detection result about an object; a wire routed to the substrate in a manner surrounding the opening; and a processing circuit mounted on the substrate that generates a noise-reduced signal in the form of an analog signal based on the difference between the sensor signal and a noise signal as an electrical signal generated in the wire. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of a sensor according to an embodiment of the present disclosure.

[0015] Figure 2 This is a diagram showing a robot equipped with sensors according to embodiments of the present disclosure.

[0016] Figure 3 This is a diagram illustrating the noise generated by the electric motor driving power flowing through the cable.

[0017] Figure 4 This is a waveform diagram illustrating the noise reduction processing of the processing circuit in the sensor according to an embodiment of the present disclosure.

[0018] Figure 5 This is a perspective view of a substrate of a first type of sensor according to an embodiment of the present disclosure.

[0019] Figure 6 This is a perspective view of a substrate of a second type in a sensor according to an embodiment of the present disclosure.

[0020] Figure 7 This is a perspective view of a third-party substrate in a sensor according to an embodiment of the present disclosure.

[0021] Figure 8 This is a circuit diagram illustrating the structure of a processing circuit in a sensor according to an embodiment of the present disclosure.

[0022] Figure 9 This is a circuit diagram illustrating the structure of the processing circuit of the second method in the sensor according to an embodiment of the present disclosure.

[0023] Figure 10 This is a circuit diagram illustrating the structure of a third-party processing circuit in a sensor according to an embodiment of the present disclosure.

[0024] Figure 11 This is a circuit diagram illustrating the structure of the processing circuit of the fourth method in the sensor according to an embodiment of the present disclosure.

[0025] Figure 12 This is a circuit diagram illustrating the structure of the processing circuit of the fifth method in the sensor according to an embodiment of the present disclosure.

[0026] Figure 13 This is an example Figure 12 The diagram shows the waveforms of each part in the processing circuit of the fifth method.

[0027] Figure 14 This is a circuit diagram illustrating the structure of the processing circuit in the sixth mode of the sensor according to an embodiment of the present disclosure.

[0028] Figure 15 This is a circuit diagram illustrating the structure of the processing circuit of the seventh mode in the sensor according to an embodiment of the present disclosure. Detailed Implementation

[0029] The sensor of the embodiment will now be described with reference to the accompanying drawings. In the following description, structures having the same or similar functions are labeled with the same symbols. Furthermore, repeated descriptions of these structures are sometimes omitted. For ease of understanding, the scale of the drawings has been appropriately changed. In the following description, "connection" refers to "electrical connection".

[0030] <Overall Structure of the Sensor>

[0031] Figure 1 This is a diagram illustrating a sensor according to an embodiment of this disclosure. Additionally, Figure 2 This is a diagram showing a robot equipped with sensors according to embodiments of the present disclosure.

[0032] The sensor 1 of the embodiments of this disclosure includes a substrate 11, a sensor circuit 12, wires 13, and a processing circuit 14. Furthermore, although not shown here, the power for driving the sensor 1 is supplied from a battery or a machine on which the sensor 1 is installed.

[0033] Sensor circuit 12 outputs a sensor detection result, i.e., a sensor signal, regarding the object 3, which is the measurement target of sensor 1. Sensor circuit 12 only needs to output a sensor signal as an analog electrical signal. Examples of sensor 1 with sensor circuit 12 include torque sensors, current sensors, voltage sensors, magnetic sensors, speed sensors, and temperature sensors.

[0034] When sensor 1 is a torque sensor, sensor circuit 12 outputs a sensor signal indicating the torque of object 3. When sensor 1 is a current sensor, sensor circuit 12 outputs a sensor signal indicating the current of object 3. When sensor 1 is a voltage sensor, sensor circuit 12 outputs a sensor signal indicating the voltage of object 3. When sensor 1 is a magnetic sensor, it outputs a sensor signal indicating the magnetic quantity of object 3. When sensor 1 is a position sensor, sensor circuit 12 outputs a sensor signal indicating the position of object 3. When sensor 1 is a velocity sensor, sensor circuit 12 outputs a sensor signal indicating the velocity of object 3. When sensor 1 is an acceleration sensor, sensor circuit 12 outputs a sensor signal indicating the acceleration of object 3. When sensor 1 is a temperature sensor, sensor circuit 12 outputs a sensor signal indicating the temperature of object 3.

[0035] In the following illustrated embodiment, the case where sensor 1 is a torque sensor is described. Sensor 1 is, for example, installed inside the arm of robot 100. Sensor circuit 12, wires 13, and processing circuit 14 are provided on the substrate 11 of sensor 1.

[0036] An opening is provided on the substrate 11 for a cable to pass through. The cable 2, through which PWM-controlled motor drive power flows, is arranged to pass through the opening. A wire 13 is routed on the substrate 11 to surround the opening. Therefore, the wire 13 is routed on the substrate 11 to surround the cable 2, which is a noise source caused by the motor drive power. The wire 13 can be routed on the surface of the substrate 11 or inside the substrate 11. The principle of noise signal generation in the wire 13 will be described later.

[0037] The processing circuit 14 generates a denoised signal in analog form or denoised sensor data in digital form based on the difference between the sensor signal in analog form output from the sensor circuit 12 and the analog electrical signal (i.e., noise signal) generated in the wire 13. Details of the noise reduction processing performed by the processing circuit 14 will be described later.

[0038] The sensor circuit 12 and the processing circuit 14 are mounted on the substrate 11.

[0039] A processing unit (processor) is provided within the sensor 1. The processing unit may include, for example, an IC, LSI, CPU, MPU, DSP, etc. The processing unit includes a sensor circuit 12, a processing circuit 14, and other processing units. These units are functional modules implemented, for example, by a program executed on the processor. For example, when the sensor circuit 12, processing circuit 14, and other processing units are constructed as a program, the functions of each unit can be realized by causing the processing unit to operate according to the program. The program for executing the processing in the sensor circuit 12, processing circuit 14, and other processing units may also be provided in the form of a computer-readable recording medium such as a semiconductor memory, magnetic recording medium, or optical recording medium. Alternatively, the sensor circuit 12, processing circuit 14, and other processing units may be implemented as semiconductor integrated circuits containing programs that implement the functions of each unit.

[0040] In addition, at least one memory, serving as a storage device, is provided within the sensor 1. The memory also includes various storage units within the sensor circuit 12, processing circuit 14, and other processing units. Examples of memory types include electrically erasable / recordable non-volatile memory such as EEPROM (registered trademark), or high-speed read / write random access memory such as DRAM or SRAM. Programs for operating the sensor circuit 12, processing circuit 14, and other processing units are stored in the memory. Furthermore, various programs and data associated with the sensor 1 are stored in the memory.

[0041] Alternatively, the wire 13 and its surrounding circuitry can be replaced with a Rogowski coil-type current detection circuit. In this case, the processing circuit 14 is connected to the Rogowski coil-type current detection circuit, and the cable 2 is configured to pass through the opening in the substrate in which the Rogowski coil is provided.

[0042] <The principle of noise generation caused by electric motor drive>

[0043] Figure 3 This is a diagram illustrating the noise generated by the electric motor driving power flowing through the cable.

[0044] Cable 2, which supplies the motor drive power after PWM control, becomes a source of noise. The motor drive power flowing in cable 2 is a rectangular wave voltage. The variations in the high and low values ​​of this rectangular wave voltage generate minute changes in the magnetic field around cable 2, which in turn superimpose noise components into the sensor signal output from sensor circuit 12 located near cable 2. For example... Figure 3 As shown, at times t2 and t4, when the motor drive power switches from low to high, a small change in the magnetic field is generated around the cable 2 through which the motor drive power flows. As a result, noise overlaps in the sensor signal output from the sensor circuit 12 located near the cable 2 at times t2 and t4.

[0045] Therefore, in embodiments of this disclosure, in order to detect changes in the magnetic field around the cable 2 through which motor drive power flows, wiring conductors 13 are routed on the substrate 11 such that the cable 2 surrounds the opening through the substrate 11. Based on changes in the motor drive power flowing through the cable 2, noise signals are generated in the wiring conductors 13.

[0046] Noise reduction processing in the processing circuit

[0047] Figure 4 This is a waveform diagram illustrating the noise reduction processing of the processing circuit in the sensor according to an embodiment of the present disclosure. Figure 4 The waveforms of the sensor signal, noise signal, and noise-reduced sensor data are shown sequentially from top to bottom. Furthermore, while the noise-reduced sensor data is normally a digital signal, it is presented in a more intuitive manner for easier understanding. Figure 4 It is illustrated in the form of analog signals.

[0048] When the PWM-controlled motor drives the power through the cable 2, which passes through the opening in the substrate 11, a slight change in the magnetic field is generated around the cable 2. This change results in noise components superimposed on the sensor signal output from the sensor circuit 12 located near the cable 2. Conversely, a noise signal corresponding to this slight change in the magnetic field is generated on the conductor 13, which is routed around the cable 2 on the substrate 11. In the processing circuit 14, by obtaining the difference between the sensor signal superimposed with the noise output from the sensor circuit 12 and the noise signal generated on the conductor 13, the noise components can be reduced (or removed) from the sensor signal. In embodiments of this disclosure, the signal output from the processing circuit 14 can be a noise-reduced signal in analog signal form or noise-reduced sensor data in digital signal form.

[0049] <Substrate with wires>

[0050] Sometimes, the substrate of the sensor 1 installed on the arm of the robot 100 has an opening for various cables to pass through. The cable 2, which carries the power to drive the motor, is also arranged to pass through the opening of the substrate. In the embodiments of this disclosure, the wire 13 is routed on the substrate 11 in such a way that it surrounds the opening of the substrate 11 of the sensor 1, thereby surrounding the cable 2. Furthermore, as a variation, an opening may be provided in the housing of the sensor 1, and the wire 13 may be routed in such a way that it surrounds the opening of the housing of the sensor 1, through which the cable 2 passes, thereby surrounding the cable 2.

[0051] The following are some examples of substrate 11 configurations.

[0052] Figure 5 This is a perspective view of a substrate representing a first embodiment of a sensor according to the present disclosure.

[0053] The substrate 11 of the first embodiment has an annular shape with an opening 50 near the center of the disc-shaped substrate. The cable 2 passes through the opening 50. A wire 13, a sensor circuit 12, and a processing circuit 14 are mounted on the substrate 11 in a manner that surrounds the opening 50.

[0054] Figure 6 This is a perspective view of a substrate of a second type in a sensor according to an embodiment of the present disclosure.

[0055] The second type of substrate 11 has a C-shaped (unclosed annular) substrate with a notch in a portion of the circumferential direction, and an opening 50 is provided near the center of the substrate. The cable 2 passes through the opening 50. A wire 13, a sensor circuit 12, and a processing circuit 14 are mounted on the substrate 11 in a C-shaped wiring manner that surrounds a portion of the opening 50.

[0056] Figure 7 This is a perspective view of a third-party substrate representing an embodiment of the sensor disclosed herein.

[0057] The substrate 11 of the third type has an opening 50 near the center of a generally quadrilateral substrate. The cable 2 passes through the opening 50. A wire 13, a sensor circuit 12, and a processing circuit 14 are mounted on the substrate 11 in a generally quadrilateral shape that surrounds the opening 50.

[0058] The first to third methods described above are examples. As long as the substrate is wired in such a way that the wire 13 surrounds the opening 50 through which the cable 2 passes, it may also have a substrate shape and wiring shape other than those shown in the figure.

[0059] <Structure of Processing Circuit>

[0060] The following are some examples of how the processing circuit 14 is processed.

[0061] Figure 8 This is a circuit diagram illustrating the structure of a processing circuit in a sensor according to an embodiment of the present disclosure.

[0062] The processing circuit 14 is connected to the sensor circuit 12 and the wires 13. Sensor elements (measuring elements) corresponding to the object 3 measured by the sensor 1 are connected to terminals P1 and P2 of the sensor circuit 12. For example, if the sensor 1 is a torque sensor, a strain gauge whose resistance value changes according to the torque applied to the motor is connected to terminals P1 and P2 of the sensor circuit 12. Alternatively, if the sensor 1 is a temperature sensor, a temperature-sensing resistor is connected to terminals P1 and P2 of the sensor circuit 12.

[0063] The processing circuit 14 of the first method has a differential amplifier circuit 23. The non-inverting input (+) of the differential amplifier circuit 23 is connected after the sensor circuit 12. The wire 13, which is routed in a manner that surrounds the cable 2, is connected to the inverting input (-) of the differential amplifier circuit 23.

[0064] The differential amplifier circuit 23 generates a noise-reduced signal in analog form by amplifying the differential signal between the sensor signal output from the sensor circuit 12 and the noise signal generated in the wire 13. The differential amplifier circuit 23 is, for example, constructed from an instrumentation amplifier. In the instrumentation amplifier, its amplification rate can be adjusted, for example, by adjusting the value of the resistor.

[0065] An AD converter 24 is connected after the differential amplifier circuit 23. The AD converter 24 converts the noise-reduced analog signal output from the differential amplifier circuit 23 into noise-reduced digital sensor data and outputs it.

[0066] Reference Figure 8 The processing circuit 14 described in the first embodiment is suitable for situations where the waveform of the noise component overlapping with the sensor signal and the waveform of the noise signal generated in the conductor 13 have the same degree of waveform shape and amplitude. The parameters of the differential amplifier circuit 23 can be set, for example, during the calibration of the sensor 1 before it leaves the factory or during performance evaluation, by an operator using a measuring device such as an oscilloscope to check each waveform while performing the setting. Alternatively, during the maintenance of the sensor 1, the operator can use a measuring device such as an oscilloscope to check each waveform while readjusting the set parameters.

[0067] Figure 9 This is a circuit diagram illustrating the structure of the processing circuit of the second method in the sensor according to an embodiment of the present disclosure.

[0068] The second processing circuit 14, based on the first processing circuit 14 described above, further includes a first low-pass filter 21 and a second low-pass filter 22 in front of the differential amplifier circuit 23.

[0069] The processing circuit 14 is connected to the sensor circuit 12 and the wire 13. Sensor elements (measuring elements) corresponding to the object 3 measured by the sensor 1 are connected to terminals P1 and P2 of the sensor circuit 12. Examples of sensor elements are given regarding the processing circuit 14 of the first embodiment described above.

[0070] The second processing circuit 14 includes a first low-pass filter 21, a second low-pass filter 22, and a differential amplifier circuit 23.

[0071] A first low-pass filter 21 is connected after the sensor circuit 12. The first low-pass filter 21 generates a first filtered signal by removing high-frequency components from the sensor signal. The parameters of the resistors and capacitors constituting the first low-pass filter 21 can be set, for example, to values ​​that can remove frequency components higher than the output period of the sensor data from the AD converter 24.

[0072] A second low-pass filter 22 is connected to a conductor 13 that is routed around cable 2. The second low-pass filter 22 generates a second filtered signal by removing high-frequency components from the noise signal. The parameters of the resistors and capacitors constituting the second low-pass filter 22 are set, for example, to values ​​that can remove frequency components higher than the output period of the sensor data from the AD converter 24.

[0073] The non-inverting (+) input of the differential amplifier circuit 23 receives the first filtered signal output from the first low-pass filter 21. The inverting (-) input of the differential amplifier circuit 23 receives the second filtered signal output from the second low-pass filter 22. The differential amplifier circuit 23 generates a noise-reduced signal by amplifying the difference between the first and second filtered signals. The differential amplifier circuit 23 is, for example, constructed from an instrumentation amplifier. In an instrumentation amplifier, its amplification rate can be adjusted, for example, by adjusting the value of a resistor.

[0074] An AD converter 24 is connected after the differential amplifier circuit 23. The AD converter 24 converts the noise-reduced analog signal output from the differential amplifier circuit 23 into noise-reduced digital sensor data and outputs it.

[0075] Reference Figure 9 The processing circuit 14 described in the second embodiment is suitable for situations where the waveform of the noise component overlapping with the sensor signal and the waveform of the noise signal generated in the conductor 13 have similar waveform shape and amplitude. The parameters of the first low-pass filter 21, the second low-pass filter 22, and the differential amplifier circuit 23 can be set, for example, during the calibration or performance evaluation phase before the sensor 1 leaves the factory, by an operator using a measuring device such as an oscilloscope to check each waveform while performing the setting. Alternatively, during the maintenance phase of the sensor 1, the operator can use a measuring device such as an oscilloscope to check each waveform while readjusting the set parameters.

[0076] Figure 10 This is a circuit diagram illustrating the structure of a third-party processing circuit in a sensor according to an embodiment of the present disclosure.

[0077] The processing circuit 14 is connected to the sensor circuit 12 and the wire 13. Sensor elements (measuring elements) corresponding to the object 3 measured by the sensor 1 are connected to terminals P1 and P2 of the sensor circuit 12. Examples of sensor elements are given regarding the processing circuit 14 of the first embodiment described above.

[0078] The third processing circuit 14 has a differential input AD converter 35. The non-inverting input (+) of the differential input AD converter 35 is connected after the sensor circuit 12. The wire 13, which is routed in a manner that surrounds the cable 2, is connected to the inverting input (-) of the differential input AD converter 35.

[0079] The differential input AD converter 35 generates a differential signal between the sensor signal in analog form and the noise signal in analog form, and converts the differential signal into noise-reduced sensor data in digital form and outputs it.

[0080] Reference Figure 10The described third-party processing circuit 14 is suitable for situations where the waveform of the noise component superimposed on the sensor signal and the waveform of the noise signal generated in the conductor 13 have the same waveform shape and amplitude. The parameters of the differential input AD converter 35 can be set, for example, during the calibration of the sensor 1 before it leaves the factory or during performance evaluation, by an operator using a measuring device such as an oscilloscope to check each waveform while performing the setting. Alternatively, during the maintenance of the sensor 1, the operator can use a measuring device such as an oscilloscope to check each waveform while readjusting the set parameters.

[0081] Figure 11 This is a circuit diagram illustrating the structure of the processing circuit of the fourth method in the sensor according to an embodiment of the present disclosure.

[0082] The processing circuit 14 is connected to the sensor circuit 12 and the wire 13. Sensor elements (measuring elements) corresponding to the object 3 measured by the sensor 1 are connected to terminals P1 and P2 of the sensor circuit 12. Examples of sensor elements are given regarding the processing circuit 14 of the first embodiment described above.

[0083] The second processing circuit 14 includes a first low-pass filter 31, a second low-pass filter 32, a first voltage follower 36, a second voltage follower 37, a first amplifier circuit 33, a second amplifier circuit 34, and a differential input AD converter 35.

[0084] A first low-pass filter 31 is connected after the sensor circuit 12. The first low-pass filter 31 generates a first filtered signal by removing high-frequency components from the sensor signal. The parameters of the resistors and capacitors constituting the first low-pass filter 31 can be set, for example, to values ​​that can remove frequency components higher than the output period of the sensor data from the differential input AD converter 35.

[0085] A first voltage follower 36 is connected after the first low-pass filter 31. The first voltage follower 36 has the function of increasing the input impedance of the non-inverting input (+) of the first voltage follower 36 as observed from the sensor circuit 12. By setting the first voltage follower 36, large currents can be prevented from flowing from the sensor circuit 12 into the first amplifier circuit 33, thus suppressing sensor errors.

[0086] A first amplifier circuit 33 is connected after the first voltage follower 36. The first amplifier circuit 33 generates a first amplified signal by amplifying the first filtered signal.

[0087] A second low-pass filter 32 is connected to a conductor 13 that is routed in a manner that surrounds cable 2. The second low-pass filter 32 generates a second filtered signal by removing high-frequency components from the noise signal. The parameters of the resistors and capacitors constituting the second low-pass filter 32 are set, for example, to values ​​that can remove frequency components higher than the output period of the sensor data from the differential input AD converter 35.

[0088] A second voltage follower 37 is connected after the second low-pass filter 32. In order to make the waveform of the noise component superimposed on the sensor signal and the waveform of the noise signal as similar as possible, a second voltage follower 37 is provided on the wiring of the noise signal, corresponding to the first voltage follower 36 provided on the wiring of the sensor signal flow.

[0089] A second amplifier circuit 34 is connected after the second voltage follower 37. The second amplifier circuit 34 generates a second amplified signal by amplifying the second filtered signal.

[0090] The first amplified signal output from the first amplifier circuit 33 is input to the non-inverting input (+) of the differential input A / D converter 35. The second amplified signal output from the second amplifier circuit 34 is input to the inverting input (-) of the differential input A / D converter 35. The differential input A / D converter 35 generates a differential signal between the first amplified signal in analog form and the second amplified signal in analog form, and converts the differential signal into noise-reduced sensor data in digital form and outputs it.

[0091] Reference Figure 11 In the processing circuit 14 described in the fourth method, the waveform of the noise component superimposed on the sensor signal has the same waveform as the noise signal generated in the conductor 13, but it is suitable for situations where there is a large difference in amplitude. The resistance values ​​of the resistors and variable resistors in the first amplifier circuit 33 and the second amplifier circuit 34 are pre-adjusted so that the amplitude of the noise component superimposed on the sensor signal is the same as the amplitude of the noise signal. The parameters of the first low-pass filter 31, the second low-pass filter 32, the first voltage follower 36, the second voltage follower 37, the first amplifier circuit 33, and the second amplifier circuit 34 are set, for example, during the calibration of the sensor 1 before leaving the factory or during the performance evaluation stage, by the operator using a measuring device such as an oscilloscope to check each waveform while performing the setting. Alternatively, during the maintenance of the sensor 1, the operator can use a measuring device such as an oscilloscope to check each waveform while readjusting the set parameters again.

[0092] Figure 12 This is a circuit diagram illustrating the structure of the processing circuit of the fifth method in the sensor according to an embodiment of the present disclosure. Additionally, Figure 13 This is an example Figure 12 The diagram shows the waveforms of each part in the processing circuit of the fifth method. Figure 13 The image shows, from top to bottom, the waveforms of the amplified signal output from amplifier circuit 42, the noise signal generated in wire 13, the regulated signal output from adjustment circuit 43, and the noise-reduced sensor data output from differential input AD converter 44. Furthermore, while the noise-reduced sensor data is normally a digital signal, it is presented in a more intuitive manner. Figure 13 It is illustrated in the form of analog signals.

[0093] The processing circuit 14 is connected to the sensor circuit 12 and the wire 13. A sensor element (measuring element) corresponding to the object 3 measured by the sensor 1 is connected to terminals P1 and P2 of the sensor circuit 12. Examples of sensor elements are given regarding the processing circuit 14 of the first embodiment described above.

[0094] The third processing circuit 14 includes a low-pass filter 41, a voltage follower 45, an amplifier circuit 42, an adjustment circuit 43, and a differential input AD converter 44.

[0095] A low-pass filter 41 is connected after the sensor circuit 12. The low-pass filter 41 generates a filtered signal by removing high-frequency components from the sensor signal. The parameters of the resistors and capacitors constituting the low-pass filter 41 can be set, for example, to values ​​that can remove frequency components higher than the output period of the sensor data from the differential input AD converter 44. Alternatively, the low-pass filter 41 can be omitted.

[0096] A voltage follower 45 is connected after the low-pass filter 41. The voltage follower 45 has the function of increasing the input impedance of the non-inverting input (+) of the voltage follower 45 as observed from the sensor circuit 12. By setting the voltage follower 45, large currents can be prevented from flowing from the sensor circuit 12 into the amplifier circuit 42, thus suppressing sensor errors.

[0097] An amplifier circuit 42 is connected after the voltage follower 45. The amplifier circuit 42 generates an amplified signal by amplifying the filtered signal.

[0098] A regulating circuit 43 is connected to a conductor 13 that is routed around cable 2. The regulating circuit 43 adjusts the amplitude of specific frequency components of the noise signal generated on conductor 13 and adjusts the phase of the noise signal, thereby generating and outputting a regulated signal. The regulating circuit 43 is designed to enable the application of sensor 1 even when the waveform of the noise component superimposed on the sensor signal is significantly different from the waveform of the noise signal generated on conductor 13. By adjusting the amplitude and phase of specific frequency components of the noise signal through the regulating circuit 43, the waveform of the noise component superimposed on the sensor signal is adjusted to have the same waveform as the noise signal generated on conductor 13. The regulating circuit 43 is configured, for example, by appropriately combining a differentiating circuit, an integrating circuit, and a bandpass filter.

[0099] The amplified signal output from amplifier circuit 42 is input to the non-inverting input (+) of differential input A / D converter 44. The regulated signal output from regulation circuit 43 is input to the inverting input (-) of differential input A / D converter 44. Differential input A / D converter 44 generates a differential signal between the amplified signal in analog form and the regulated signal in analog form, and converts the differential signal into noise-reduced sensor data in digital form and outputs it.

[0100] Reference Figure 12 and Figure 13 The processing circuit 14 of the fifth method described is suitable for situations where the waveform of the noise component superimposed on the sensor signal is significantly different from the waveform of the noise signal generated in the conductor 13. For example, when the sensor signal output from the sensor circuit 12 is an analog signal representing the voltage applied to the electrostatic capacitor, the electrostatic capacitor is a physical quantity related to the electric field, but the noise signal is strongly related to the magnetic field. Therefore, the phase and frequency of the waveforms of the noise component superimposed on the sensor signal and the noise signal generated in the conductor 13 are significantly different. In the third-method processing circuit 14, the parameters of the amplifier circuit 42 and the adjustment circuit 43 are pre-adjusted so that the amplitude of the noise component superimposed on the sensor signal is the same as the amplitude of the noise signal. The parameters of the low-pass filter 41, voltage follower 45, amplifier circuit 42, and adjustment circuit 43 can be set, for example, during the calibration of the sensor 1 before leaving the factory or during performance evaluation, by the operator using a measuring device such as an oscilloscope to check each waveform while performing the setting. Alternatively, the parameters can be readjusted again by the operator using a measuring device such as an oscilloscope to check each waveform during the maintenance of the sensor 1.

[0101] Figure 14 This is a circuit diagram illustrating the structure of the processing circuit in the sixth mode of the sensor according to an embodiment of the present disclosure.

[0102] The processing circuit 14 is connected to the sensor circuit 12 and the wire 13. A sensor element (measuring element) corresponding to the object 3 measured by the sensor 1 is connected to terminals P1 and P2 of the sensor circuit 12. Examples of sensor elements are given regarding the processing circuit 14 of the first embodiment described above.

[0103] The processing circuit 14 of the sixth method has a first AD converter 53, a second AD converter 54, and a differential operation circuit 55.

[0104] A first AD converter 53 is connected after the sensor circuit 12. The first AD converter 53 converts the sensor signal in analog form into first digital data in digital form.

[0105] The conductor 13, which is routed in a manner that surrounds cable 2, is connected to the second AD converter 54. The second AD converter 54 converts the noise signal generated by the conductor 13 from the form of an analog signal into second digital data from the form of a digital signal.

[0106] A differential operation circuit 55 is connected after the first AD converter 53 and the second AD converter 54. The differential operation circuit 55 amplifies the first digital data through digital processing to generate first amplified digital data. Additionally, the differential operation circuit 55 amplifies the second digital data through digital processing to generate second amplified digital data, or it adjusts the amplitude of specific frequency components of the second digital data using digital filtering and adjusts the phase of the second digital data using digital processing to generate adjusted digital data. By obtaining the difference between the first and second amplified digital data, or the difference between the first amplified digital data and the adjusted digital data, digital processing to generate noise-reduced sensor data is performed. The differential operation circuit 55 may be composed of, for example, an IC, LSI, CPU, MPU, DSP, etc.

[0107] Reference Figure 14 The processing circuit 14 described in the sixth method is suitable for situations where the processing speed of the differential operation circuit 55 is sufficiently fast compared to the main frequency components contained in the waveforms of the sensor signal and the noise signal. The parameters of the first AD converter 53, the second AD converter 54, and the differential operation circuit 55 can be set, for example, during the calibration of the sensor 1 before it leaves the factory or during performance evaluation, by an operator using a measuring device such as an oscilloscope to check each waveform while performing the setting. Alternatively, during the maintenance of the sensor 1, the operator can use a measuring device such as an oscilloscope to check each waveform while readjusting the set parameters again.

[0108] Figure 15 This is a circuit diagram illustrating the structure of the processing circuit of the seventh mode in the sensor according to an embodiment of the present disclosure.

[0109] The seventh processing circuit 14 is based on the sixth processing circuit 14 described above, and a first low-pass filter 51 and a second low-pass filter 52 are further provided in front of the differential operation circuit 55.

[0110] The processing circuit 14 is connected to the sensor circuit 12 and the wire 13. A sensor element (measuring element) corresponding to the object 3 measured by the sensor 1 is connected to terminals P1 and P2 of the sensor circuit 12. Examples of sensor elements are given regarding the processing circuit 14 of the first embodiment described above.

[0111] The processing circuit 14 of the seventh method includes a first low-pass filter 51, a second low-pass filter 52, a first AD converter 53, a second AD converter 54, and a differential operation circuit 55.

[0112] A first low-pass filter 51 is connected after the sensor circuit 12. The first low-pass filter 51 generates a first filtered signal by removing high-frequency components from the sensor signal. The parameters of the resistors and capacitors constituting the first low-pass filter 51 can be set, for example, to values ​​that can remove frequency components higher than the output period of the sensor data from the first AD converter 53.

[0113] A second low-pass filter 52 is connected to a conductor 13 that is routed around cable 2. The second low-pass filter 52 generates a second filtered signal by removing high-frequency components from the noise signal. The parameters of the resistors and capacitors constituting the second low-pass filter 52 are set, for example, to values ​​that can remove frequency components higher than the output period of the sensor data from the second AD converter 54.

[0114] The first filtered signal output from the first low-pass filter 51 is input to the first A / D converter 53. The first A / D converter 53 converts the first filtered signal in analog form into first filtered digital data in digital form.

[0115] The second filtered signal output from the second low-pass filter 52 is input to the second AD converter 54. The second AD converter 54 converts the second filtered signal in analog form into second filtered digital data in digital form.

[0116] A differential operation circuit 55 is connected after the first AD converter 53 and the second AD converter 54. The differential operation circuit 55 amplifies the first filtered digital data through digital processing, thereby generating first amplified digital data. Additionally, the differential operation circuit 55 amplifies the second filtered digital data through digital processing, thereby generating second amplified digital data, or adjusts the amplitude of specific frequency components of the second filtered digital data through digital filtering, and adjusts the phase of the second filtered digital data through digital processing, thereby generating adjusted digital data. By obtaining the difference between the first amplified digital data and the second amplified digital data, or the difference between the first amplified digital data and the adjusted digital data, digital processing to generate noise-reduced sensor data is performed. The differential operation circuit 55 may be composed of, for example, an IC, LSI, CPU, MPU, DSP, etc.

[0117] Reference Figure 15 The processing circuit 14 described in the seventh method is suitable for situations where the processing speed of the differential operation circuit 55 is sufficiently fast compared to the main frequency components contained in the waveforms of the sensor signal and the noise signal. The parameters of the first low-pass filter 51, the second low-pass filter 52, the first AD converter 53, the second AD converter 54, and the differential operation circuit 55 can be set, for example, during the calibration or performance evaluation phase before the sensor 1 leaves the factory, by an operator using a measuring device such as an oscilloscope to check each waveform while performing the setting. Alternatively, during the maintenance phase of the sensor 1, the operator can use a measuring device such as an oscilloscope to check each waveform while readjusting the set parameters again.

[0118] <Advantages of the embodiments of the present invention>

[0119] According to embodiments of this disclosure, noise can be accurately detected, thereby reducing the impact of noise on the sensor output.

[0120] Typically, the motor drive power after PWM control switches between high and low frequencies at high speeds, making sensor data from sensors located around the cables through which the motor drive power flows susceptible to noise. For example, conventional methods reduce the impact of noise on sensor output by averaging sensor data over time, but this results in a loss of high-speed sensor processing. Furthermore, robots and machine tools often perform complex movements, and the loads applied to them vary, causing drastic waveform changes in the motor drive power flowing through the cables and resulting in poor reproducibility. In contrast, according to embodiments of this disclosure, by using wires routed around the cables, noise signals caused by variations in the motor drive power flowing through the cables can be accurately detected. The noise signals detected by the wires are used to cancel out the noise components of the sensor signal output from the sensor circuit, thereby generating sensor data with reduced noise impact, thus ensuring both high-speed and accurate sensor processing.

[0121] Furthermore, for example, sometimes the substrate of a sensor mounted on a robot arm has openings for various cables to pass through. Generally, when components are mounted or wired on a substrate, the presence of openings in the substrate often restricts the placement of components and the wiring pattern. In contrast, in the embodiments of this disclosure, noise signals can be detected simply by wiring the wires around the openings in the substrate of the sensor, thus avoiding the need for a large sensor associated with the circuitry used to detect noise signals.

[0122] The present disclosure has been described in detail above, but it is not limited to the various embodiments and modifications described above. These embodiments and modifications can be supplemented, substituted, modified, or partially deleted in various ways without departing from the spirit of the present disclosure or from the spirit of the present disclosure derived from the content described under the scope of the claimed patent protection and its equivalents. Furthermore, these embodiments and modifications can also be implemented in combination. For example, in the embodiments and modifications described above, the order of each action and the order of each process are shown as examples and are not limited thereto. The same applies to the use of numerical values ​​or mathematical formulas in the descriptions of the embodiments and modifications described above.

[0123] <Postscript>

[0124] The following notes further disclose the above-described embodiments and variations.

[0125] (Note 1)

[0126] A sensor includes: a substrate having an opening through which a cable passes; a sensor circuit mounted on the substrate that outputs a sensor signal in the form of an analog signal as a sensor detection result about an object; a wire wire that is routed on the substrate in a manner surrounding the opening; and a processing circuit mounted on the substrate that generates a noise-reduced signal in the form of an analog signal based on the difference between the sensor signal and a noise signal that is an electrical signal generated in the wire.

[0127] (Note 2)

[0128] According to the sensor described in Appendix 1, the processing circuit includes a differential amplifier circuit that generates a noise-reduced signal by amplifying the differential signal between the sensor signal and the noise signal.

[0129] (Note 3)

[0130] According to the sensor described in Appendix 2, the sensor further comprises: an AD converter that converts the noise-reduced signal in analog form from the differential amplifier circuit output into noise-reduced sensor data in digital form.

[0131] (Note 4)

[0132] According to the sensor described in Appendix 1, the processing circuit includes: a first low-pass filter that generates a first filtered signal by removing high-frequency components from the sensor signal; a second low-pass filter that generates a second filtered signal by removing high-frequency components from the noise signal; and a differential amplifier circuit that generates a noise-reduced signal by amplifying the differential signal between the first filtered signal output from the first low-pass filter and the second filtered signal output from the second low-pass filter.

[0133] (Note 5)

[0134] According to the sensor described in Appendix 4, the sensor further comprises: an AD converter that converts the noise-reduced signal in analog form from the differential amplifier circuit output into noise-reduced sensor data in digital form.

[0135] (Note 6)

[0136] A sensor includes: a substrate having an opening through which a cable passes; a sensor circuit mounted on the substrate that outputs a sensor signal in the form of an analog signal as a sensor detection result about an object; a wire that is wired on the substrate in a manner surrounding the opening; and a processing circuit mounted on the substrate that generates noise-reduced sensor data in the form of a digital signal based on the difference between the sensor signal and a noise signal as an electrical signal generated in the wire.

[0137] (Note 7)

[0138] According to the sensor described in Appendix 6, the processing circuit includes: a differential input AD converter that generates a differential signal between a sensor signal in analog signal form and a noise signal in analog signal form, and converts the differential signal into noise-reduced sensor data in digital signal form.

[0139] (Postscript 8)

[0140] According to the sensor described in Appendix 6, the processing circuit includes: a first low-pass filter that generates a first filtered signal by removing high-frequency components from the sensor signal; a second low-pass filter that generates a second filtered signal by removing high-frequency components from the noise signal; a first amplifier circuit that generates a first amplified signal by amplifying the first filtered signal output from the first low-pass filter; a second amplifier circuit that generates a second amplified signal by amplifying the second filtered signal output from the second low-pass filter; and a differential input AD converter that generates a differential signal between the first amplified signal in analog form output from the first amplifier circuit and the second amplified signal in analog form output from the second amplifier circuit, and converts the differential signal into noise-reduced sensor data in digital form.

[0141] (Note 9)

[0142] According to the sensor described in Appendix 6, the processing circuit includes: a low-pass filter that generates a filtered signal by removing high-frequency components from the sensor signal; an amplifier circuit that generates an amplified signal by amplifying the filtered signal output from the low-pass filter; a conditioning circuit that outputs a conditioned signal obtained by performing phase conditioning and amplitude conditioning of specific frequency components on the noise signal; and a differential input A / D converter that generates a differential signal between the amplified signal in analog signal form output from the amplifier circuit and the conditioned signal in analog signal form output from the conditioning circuit, and converts the differential signal into noise-reduced sensor data in digital signal form.

[0143] (Postscript 10)

[0144] According to the sensor described in Appendix 6, the processing circuit includes: a first AD converter that converts a sensor signal in analog signal form into first digital data in digital signal form; a second AD converter that converts a noise signal in analog signal form into second digital data in digital signal form; and a differential operation circuit that generates noise-reduced sensor data by taking the difference between a first amplified digital data obtained by amplifying the first digital data and a second amplified digital data obtained by amplifying the second digital data.

[0145] (Postscript 11)

[0146] According to the sensor described in Appendix 6, the processing circuit includes: a first AD converter that converts a sensor signal in analog signal form into first digital data in digital signal form; a second AD converter that converts a noise signal in analog signal form into second digital data in digital signal form; and a differential operation circuit that generates noise-reduced sensor data by taking the difference between a first amplified digital data obtained by amplifying the first digital data and an adjusted digital data obtained by performing phase adjustment and amplitude adjustment of a specific frequency component on the second digital data.

[0147] (Postscript 12)

[0148] According to the sensor described in Appendix 6, the processing circuit includes: a first low-pass filter that generates a first filtered signal by removing high-frequency components from the sensor signal; a second low-pass filter that generates a second filtered signal by removing high-frequency components from the noise signal; a first analog-to-digital converter that converts the first filtered signal in analog signal form output from the first low-pass filter into first filtered digital data in digital signal form; a second analog-to-digital converter that converts the second filtered signal in analog signal form output from the second low-pass filter into second filtered digital data in digital signal form; and a differential operation circuit that generates noise-reduced sensor data by taking the difference between the first filtered digital data and the second filtered digital data.

[0149] (Postscript 13)

[0150] According to the sensor described in Appendix 6, the processing circuit includes: a first low-pass filter that generates a first filtered signal by removing high-frequency components from the sensor signal; a second low-pass filter that generates a second filtered signal by removing high-frequency components from the noise signal; a first analog-to-digital converter that converts the first filtered signal in analog signal form output from the first low-pass filter into first filtered digital data in digital signal form; a second analog-to-digital converter that converts the second filtered signal in analog signal form output from the second low-pass filter into second filtered digital data in digital signal form; and a differential operation circuit that generates noise-reduced sensor data by taking the difference between a first amplified digital data obtained by amplifying the first filtered digital data and an adjusted digital data obtained by performing phase adjustment and amplitude adjustment of specific frequency components on the second filtered digital data.

[0151] (Postscript 14)

[0152] According to any one of Appendices 1 to 13, the sensor circuit outputs a sensor signal representing the torque of the object, a sensor signal representing the current of the object, a sensor signal representing the voltage of the object, a sensor signal representing the magnetic quantity of the object, a sensor signal representing any one of the position, velocity and acceleration of the object, and a sensor signal representing any one of the temperature of the object.

[0153] Explanation of reference numerals in the attached figures

[0154] 1 sensor

[0155] 2 cables

[0156] 3 objects

[0157] 11 substrate

[0158] 12-sensor circuit

[0159] 13 conductors

[0160] 14 Processing Circuits

[0161] 21 First low-pass filter

[0162] 22 Second low-pass filter

[0163] 23 Differential Amplifier Circuit

[0164] 24 AD converter

[0165] 31 First low-pass filter

[0166] 32 Second Low-Pass Filter

[0167] 33 First Amplifier Circuit

[0168] 34 Second Amplifier Circuit

[0169] 35 Differential Input A / D Converter

[0170] 36 First Voltage Follower

[0171] 37 Second Voltage Follower

[0172] 41 Low-pass filter

[0173] 42 amplifier circuit

[0174] 43 Adjustment Circuit

[0175] 44 Differential Input A / D Converter

[0176] 45V voltage follower

[0177] 50 opening

[0178] 51 First Low-Pass Filter

[0179] 52 Second Low-Pass Filter

[0180] 53 First AD Converter

[0181] 54 Second AD Converter

[0182] 55 Differential operational circuit.

Claims

1. A sensor, characterized in that, have: A substrate having an opening for a cable to pass through; A sensor circuit, mounted on the substrate, outputs a sensor signal in the form of an analog signal about the sensor detection result of the object. A wire, which is routed on the substrate in a manner that surrounds the opening; as well as A processing circuit, mounted on the substrate, generates a noise-reduced signal in the form of an analog signal based on the difference between the sensor signal and a noise signal that is an electrical signal generated in the conductor.

2. The sensor according to claim 1, characterized in that, The processing circuit includes a differential amplifier circuit that generates the noise-reduced signal by amplifying the differential signal between the sensor signal and the noise signal.

3. The sensor according to claim 2, characterized in that, The sensor also includes an AD converter that converts the noise-reduced signal, in analog form, output from the differential amplifier circuit, into noise-reduced sensor data in digital form.

4. The sensor according to claim 1, characterized in that, The processing circuit has: A first low-pass filter generates a first filtered signal by removing high-frequency components from the sensor signal; A second low-pass filter generates a second filtered signal by removing high-frequency components from the noise signal; as well as A differential amplifier circuit generates the noise-reduced signal by amplifying the differential signal between the first filtered signal output from the first low-pass filter and the second filtered signal output from the second low-pass filter.

5. The sensor according to claim 4, characterized in that, The sensor also includes an AD converter that converts the noise-reduced signal, in analog form, output from the differential amplifier circuit, into noise-reduced sensor data in digital form.

6. A sensor, characterized in that, have: A substrate having an opening for a cable to pass through; A sensor circuit, mounted on the substrate, outputs a sensor signal in the form of an analog signal about the sensor detection result of the object. A wire, which is routed on the substrate in a manner that surrounds the opening; as well as A processing circuit, mounted on the substrate, generates noise-reduced sensor data in digital signal form based on the difference between the sensor signal and a noise signal that is an electrical signal generated in the conductor.

7. The sensor according to claim 6, characterized in that, The processing circuit includes: a differential input AD converter that generates a differential signal between the sensor signal in analog form and the noise signal in analog form, and converts the differential signal into the noise-reduced sensor data in digital form.

8. The sensor according to claim 6, characterized in that, The processing circuit has: A first low-pass filter generates a first filtered signal by removing high-frequency components from the sensor signal; A second low-pass filter generates a second filtered signal by removing high-frequency components from the noise signal; The first amplifier circuit generates a first amplified signal by amplifying the first filtered signal output from the first low-pass filter; The second amplifier circuit generates a second amplified signal by amplifying the second filtered signal output from the second low-pass filter; and A differential input A / D converter generates a differential signal between a first amplified signal in analog form output from a first amplification circuit and a second amplified signal in analog form output from a second amplification circuit, and converts the differential signal into the noise-reduced sensor data in digital form.

9. The sensor according to claim 6, characterized in that, The processing circuit has: A low-pass filter generates a filtered signal by removing high-frequency components from the sensor signal; An amplifier circuit generates an amplified signal by amplifying the filtered signal output from the low-pass filter; An adjustment circuit, the output of which is an adjusted signal obtained by performing phase adjustment and amplitude adjustment of specific frequency components on the noise signal; as well as A differential input A / D converter generates a differential signal between the amplified signal in analog form output from the amplification circuit and the regulated signal in analog form output from the regulation circuit, and converts the differential signal into the noise-reduced sensor data in digital form.

10. The sensor according to claim 6, characterized in that, The processing circuit has: A first AD converter converts the sensor signal in analog signal form into first digital data in digital signal form; A second AD converter converts the noise signal in analog signal form into second digital data in digital signal form; and The differential operation circuit generates the noise-reduced sensor data by taking the difference between the first amplified digital data (after amplifying the first digital data) and the second amplified digital data (after amplifying the second digital data).

11. The sensor according to claim 6, characterized in that, The processing circuit has: A first AD converter converts the sensor signal in analog signal form into first digital data in digital signal form; A second AD converter converts the noise signal in analog signal form into second digital data in digital signal form; and The differential operation circuit generates the noise-reduced sensor data by taking the difference between the first amplified digital data obtained by amplifying the first digital data and the adjusted digital data obtained by performing phase adjustment and amplitude adjustment of specific frequency components on the second digital data.

12. The sensor according to claim 6, characterized in that, The processing circuit has: A first low-pass filter generates a first filtered signal by removing high-frequency components from the sensor signal; A second low-pass filter generates a second filtered signal by removing high-frequency components from the noise signal; A first AD converter converts the first filtered signal, in analog form, output from the first low-pass filter into first filtered digital data in digital form. A second AD converter converts the second filtered signal, in analog form, output from the second low-pass filter into second filtered digital data, in digital form; and The differential operation circuit generates the noise-reduced sensor data by taking the difference between the first amplified digital data (after amplifying the first filtered digital data) and the second amplified digital data (after amplifying the second filtered digital data).

13. The sensor according to claim 6, characterized in that, The processing circuit has: A first low-pass filter generates a first filtered signal by removing high-frequency components from the sensor signal; A second low-pass filter generates a second filtered signal by removing high-frequency components from the noise signal; A first AD converter converts the first filtered signal, in analog form, output from the first low-pass filter into first filtered digital data in digital form. A second AD converter converts the second filtered signal, in analog form, output from the second low-pass filter into second filtered digital data, in digital form; and The differential operation circuit generates the noise-reduced sensor data by taking the difference between the first amplified digital data obtained by amplifying the first filtered digital data and the adjusted digital data obtained by performing phase adjustment and amplitude adjustment of specific frequency components on the second filtered digital data.

14. The sensor according to any one of claims 1 to 13, characterized in that, The sensor circuit outputs a sensor signal representing the torque of the object, a sensor signal representing the current of the object, a sensor signal representing the voltage of the object, a sensor signal representing the magnetic quantity of the object, a sensor signal representing any one of the position, velocity, and acceleration of the object, and a sensor signal representing the temperature of the object.

Images