JP2019002808A - Underground survey system - Google Patents

Abstract

To provide an underground survey system that can make a sensitive detection at low power consumption.SOLUTION: The present invention includes: a data center 100 connected to an earthquake generating car 101; a repeater 102 connected to the data center 100; and a sensor 103 connected to the repeater 102. The data center 100 determines a dynamic range to be set for the sensor 103 on the basis of earthquake information and the positional information of the sensor 103, and sends the dynamic range to the sensor 103 through the repeater 102.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an underground exploration system.

  There is an acceleration sensor system that acquires valuable information by detecting an acceleration signal of an object using an acceleration sensor and analyzing the data. The acceleration sensor system is used for various purposes, and includes, for example, seismic measurement, resource exploration such as oil and natural gas, state detection of buried objects such as water supply and gas pipes, and the like.

  For example, in the case of resource exploration, the acceleration sensor system analyzes the received data by receiving the reflected wave from the underground structure of the vibration caused by the seismic device by the acceleration sensor. Thereby, the underground structure information that can be used for estimating the position where the resource exists as valuable information is output.

  As an acceleration sensor system, there is a system using a servo-type capacitive sensor as a configuration for realizing high-sensitivity, that is, high-accuracy acceleration detection.

  As a prior art related to a servo-type capacitive acceleration sensor system, for example, Patent Document 1 can be cited. In Patent Document 1, an acceleration sensor includes an acceleration detection element having a movable electrode and a fixed electrode, capacitance detection means for detecting a capacitance difference between the electrodes, and static electricity that allows the movable electrode to return to a reference position based on the detection. Electrostatic force generating means for generating a force on the electrodes. The electrostatic force generating means applies a rectangular wave voltage by pulse width modulation (PWM) to the electrodes at a predetermined repetition period, and changes the ratio of the voltage application time and the repetition period in accordance with the capacitance difference.

JP-A-4-337468

  In the acceleration sensor system, the maximum electrostatic force that can be applied for servo control, that is, the servo force, is uniquely determined by the servo voltage applied between the electrodes. In the servo system, when the input acceleration exceeding the servo force is received, the servo control becomes impossible and the output signal of the sensor does not coincide with the input acceleration signal. In order to ensure the continuity of data, it is necessary to increase the servo voltage and expand the acceleration range in which servo control is possible. However, power consumption increases in proportion to the square of the servo voltage.

  For this reason, when applying the acceleration sensor system of patent document 1 to various uses, it may not be efficient in terms of power consumption. For example, in the case of resource exploration, as a typical example of the time change of acceleration, the acceleration is steady and minute in normal times, and the vibration received by a sensor near the shaking device and the direct wave immediately after the shaking have a large acceleration. The acceleration decreases with time.

  In this case, a large servo force is required immediately after the earthquake, but the acceleration is small and the necessary electrostatic force is small after normal or after a lapse of time. In other words, the longer the time during which the acceleration is low, the longer the time period that requires excessive power consumption.

  An object of the present invention is to provide an underground exploration system capable of high sensitivity detection with low power consumption.

  An underground exploration system according to one aspect of the present invention includes a seismic device, a data center connected to the seismic device, a repeater connected to the data center, and first and first connected to the repeater. And the data center has a first dynamic range set in the first sensor based on the earthquake information of the earthquake device and the position information of the first and second sensors. And a second dynamic range that is different from the first dynamic range set in the second sensor is transmitted to the first and second sensors via the repeater, respectively. And

  According to one embodiment of the present invention, an underground exploration system capable of high sensitivity detection with low power consumption can be realized.

It is a block diagram which shows the underground exploration system of Example 1. FIG. 1 is a circuit diagram of a sensor of Example 1. FIG. 1 is a circuit diagram of a sensor of Example 1. FIG. 1 is a circuit diagram of a sensor of Example 1. FIG. FIG. 3 is an operation timing chart of the sensor of Example 1. 6 is a circuit diagram of a sensor of Example 2. FIG. 6 is a circuit diagram of a sensor of Example 2. FIG. It is a block diagram of a data center. It is detail drawing of the table of a data center.

First, an embodiment will be described.
The embodiment includes a seismic device, a data center that communicates seismic control information, a repeater that communicates seismic control information from the data center, and a servo that bidirectionally communicates seismic control information from the repeater. It is an underground exploration system with a type sensor. The data center obtains a dynamic range to be set for each sensor from the earthquake control information of the earthquake generator and the position information of the servo sensor, and distributes it to each servo sensor via a repeater. The servo type sensor controls the servo voltage value based on the information, and controls the dynamic range of the servo type sensor. According to the embodiment, since an appropriate dynamic range can be set based on the earthquake control information, the power consumption of each sensor can be reduced.
Hereinafter, embodiments will be described in detail with reference to the drawings.

With reference to FIG. 1, the underground exploration system of Example 1 is demonstrated.
It is an example in the case of using a seismic vehicle (vibrose) for a seismic device. Here, the seismic device may have dynamite. In the first embodiment, the sensor position information transmitted from the sensor and the seismic control information of the data center are combined and analyzed, and the dynamic range of the sensor is adjusted.

  As shown in FIG. 1, the underground exploration system includes seismic vehicles 101a and 101b, a data center 100 connected to the seismic vehicles 101a and 102b, a repeater 102 connected to the data center 100, and a repeater 102. The sensors 103a, 103b, 103c, 103d, 103e, and 103f are connected to each other.

  The data center 100 acquires the seismic control information of the seismic vehicles 101a, 102b and the position information of the sensors 103a, 103b, 103c, 103d, 103e, 103f, and the seismic control information of the seismic vehicles 101a, 102b and the sensor 103a , 103b, 103c, 103d, 103e, and 103f, the dynamic ranges set for the sensors 103a, 103b, 103c, 103d, 103e, and 103f are obtained, and the sensors 103a and 103b are connected via the repeater 102. , 103c, 103d, 103e, and 103f. Each sensor 103a, 103b, 103c, 103d, 103e, 103f sets a servo voltage value based on the dynamic range sent via the repeater 102.

  In this way, the data center 100 controls the earthquake control information of the earthquake vehicles 101a and 102b, and the positions and failures of the earthquake vehicles 101a and 102b and the sensors 103a, 103b, 103c, 103d, 103e, and 103f. And collect and analyze information such as power management. Each of the sensors 103a, 103b, 103c, 103d, 103e, and 103f and the seismic vehicles 101a and 102b has a GPS function and can grasp position information thereof. Here, the position information includes latitude, longitude, and altitude information.

  As shown in FIG. 8, the data center 100 includes a sensor information receiving unit 1001, a seismic vehicle information receiving unit 1001, a control unit 1000, a table 1003, a sensor information transmitting unit 1004, and a seismic vehicle information transmitting unit 1005. The sensor information receiving unit 1001 and the earthquake vehicle information receiving unit 1002 receive various information (position, failure, power management, etc.) of the sensors 103a, 103b, 103c, 103d, 103e, and 103f and the earthquake vehicles 101a and 102b, respectively. . The control unit 1000 stores the positions of the sensors 103a, 103b, 103c, 103d, 103e, 103f and the seismic wheels 101a, 102b in the table 1003.

  The control unit 1000 calculates the positional relationship between the sensors 103a, 103b, 103c, 103d, 103e, and 103f and the earthquake wheels 101a and 102b using the position information stored in the table 1003. As a result, the table shows the earthquake setting (amplitude, sweep frequency, earthquake time) and the operation mode (dynamic range setting value and time for applying the setting value) of the sensors 103a, 103b, 103c, 103d, 103e, and 103f. Store.

  For example, the sensors 103a, 103b, and 103c close to the positions of the seismic vehicles 101a and 101b increase the dynamic range, and the distant sensors 103d, 103e, and 103f decrease the dynamic range. In addition, the dynamic range is increased during a period when a direct wave due to seismic motion is expected, and the dynamic range is decreased after arrival.

  As shown in FIG. 9, when switching between two types of operation modes by time, dynamic range setting values and time information for applying the setting values are stored in operation mode A and operation mode B, respectively. The operation mode setting and the earthquake setting stored in the table 1003 are obtained by using the sensor information transmission unit 1004 and the earthquake vehicle information transmission unit 1005, respectively, and the respective sensors 103a, 103b, 103c, 103d, 103e, 103f and the earthquake occurrence. It is transmitted to the cars 101a and 102b. The seismic vehicles 101a and 101b press the weight attached to the bottom surface with a specified setting based on the information received from the data center 100 against the ground.

  The sensors 103a, 103b, 103c, 103d, 103e, and 103f detect reflected waves from the boundary surface of the underground structure due to vibrations caused by the seismic vehicles 101a and 101b. The repeater 102 mediates information exchanged between the data center 100 and the sensors 103a, 103b, 103c, 103d, 103e, and 103f. In particular, in the field of resource exploration, sensors with a scale of 1 million units are deployed, so a repeater 102 is required between the data center 100 and the sensors 103a, 103b, 103c, 103d, 103e, and 103f.

Next, the configuration of the sensor of the first embodiment will be described with reference to FIG.
The capacitive MEMS 1 includes four detection MEMS capacitive elements 1a, 1b, 1c, and 1d. In order to perform servo control, two servo control MEMS capacitance elements 1e and 1f are further provided. Here, MEMS (Micro Electro Mechanical Systems) refers to a device in which mechanical element parts, sensors, actuators, and electronic circuits are integrated on a single silicon substrate, glass substrate, organic material, etc. by microfabrication technology. .

  From the first pair of detection MEMS capacitive elements 1a and 1b, the second pair of detection MEMS capacitive elements 1c and 1d, and the servo control MEMS capacitive elements 1e and 1f Each of the third pair structures is designed to be as identical as possible.

The movable electrodes of the detection MEMS capacitive elements 1a, 1b, 1c, and 1d are electrodes on the operational amplifier side of these capacitive elements. On the other hand, the fixed electrodes of the detection MEMS capacitive elements 1a, 1b, 1c, and 1d are connected to the carrier clock φ _CP , the inverted carrier clock φ _CPB , the inverted carrier clock φ _CHB , and the carrier clock φ _CP generated by the high-voltage circuit 9, respectively. Has been.

A fixed voltage V _SVB is applied to the movable electrodes of the servo control MEMS capacitive elements 1e and 1f. On the other hand, the fixed electrodes of the MEMS capacitor elements 1e and 1f for servo control are connected to the servo clock φ _SV and the inverted servo clock φ _SVB generated by the high voltage circuit 9, respectively.

The other electrodes (fixed electrodes) of the detection MEMS capacitive elements 1a, 1b, 1c, and 1d of the capacitive MEMS 1 are connected to the inverting input terminals of the operational amplifiers 3a and 3b, respectively. Further, feedback capacitive elements 4a (capacitance value C _F ), 4b (capacitance value C _F ) and resistance elements 5a (resistance value R _F ), 5b (resistance value) are provided between the inverting input terminals and output terminals of the operational amplifiers 3a and 3b, respectively. R _F ) is provided. A switch may be provided between the feedback capacitive elements 4a and 4b and the operational amplifiers 3a and 3b. Further, the operational amplifier 3a, the non-inverting input terminal of 3b is connected to the voltage _{V B.} Here, V _B = V _DD / 2.

  In the configuration of FIG. 4, unlike the configuration of FIG. 2, switches 20a and 20b are provided between the inverting input terminals and the output terminals of the operational amplifiers 3a and 3b instead of the resistance elements 5a and 5b. For this reason, a signal for driving the switch is required. While the configuration of FIG. 2 continuously detects a capacitance change as a voltage change, the configuration of FIG. 4 differs in that the capacitance change is sampled and held as a voltage change.

  Outputs of the operational amplifiers 3a and 3b of the CV conversion amplifier are connected to a differential input terminal of the A / D converter 7 through filters 6a and 6b. The A / D converter 7 uses differential inputs to remove common mode noise and interference.

Next, the operation of the circuit of FIG. 2 will be described.
The movable electrode of the detection MEMS capacitive element 1a, the movable electrode of the detection MEMS capacitive element 1b, the movable electrode of the detection MEMS capacitive element 1c, and the movable electrode of the detection MEMS capacitive element 1d are mechanically moved so as to move together. And mechanically functions as a single weight (mass body). When a signal such as acceleration is not applied to the sensor, a force such as an inertial force does not act on the weight. Therefore, the weight, that is, the movable electrode of the detection MEMS capacitive element 1a and the movable electrode of the detection MEMS capacitive element 1b The movable electrode of the detection MEMS capacitive element 1c and the movable electrode of the detection MEMS capacitive element 1d are located at an initial location.

  When a signal such as acceleration is applied to the sensor, the weight receives a force such as an inertial force proportional to the signal such as acceleration, whereby the weight, that is, the movable electrode of the detection MEMS capacitive element 1a and the detection MEMS. The positions of the movable electrode of the capacitive element 1b, the movable electrode of the detection MEMS capacitive element 1c, and the movable electrode of the detection MEMS capacitive element 1d are integrally displaced in proportion to a signal such as acceleration. Thereby, when the movable electrode of the detection MEMS capacitive element 1a is displaced so as to approach the fixed electrode of the detection MEMS capacitive element 1a, the movable electrode of the detection MEMS capacitive element 1b is fixed to the detection MEMS capacitive element 1b. Move away from the electrode by the same amount of displacement.

  When the movable electrode of the detection MEMS capacitive element 1a is displaced away from the fixed electrode of the detection MEMS capacitive element 1a, on the contrary, the movable electrode of the detection MEMS capacitive element 1b becomes the fixed electrode of the detection MEMS capacitive element 1b. From the same distance. Similarly, when the movable electrode of the detection MEMS capacitive element 1c is displaced so as to approach the fixed electrode of the detection MEMS capacitive element 1c, conversely, the movable electrode of the detection MEMS capacitive element 1d is fixed to the detection MEMS capacitive element 1d. Move away from the electrode by the same amount of displacement.

  When the movable electrode of the detection MEMS capacitive element 1c is displaced away from the fixed electrode of the detection MEMS capacitive element 1c, conversely, the movable electrode of the detection MEMS capacitive element 1d becomes the fixed electrode of the detection MEMS capacitive element 1d. From the same distance.

  If the change in capacitance value due to the amount of displacement, that is, the change in electrode plate spacing is ΔC, the capacitance values of the detection MEMS capacitive elements 1a and 1c are C + ΔC, and the capacitance values of the detection MEMS capacitive elements 1b and 1d are C−ΔC. Become.

FIG. 5 shows waveforms of the carrier clock 40, the inverted carrier clock 41, and the clock signal 42. Each clock is generated by the high voltage circuit 9. In the clock signal 42, the switch 20a and the switch 20b are turned on when a high potential signal (for example, V _DD ) is input and turned off when a low potential signal (for example, GND) is input.

  During the operation of the sensor, the CV conversion amplifier converts a MEMS capacitance change ΔC caused by a signal such as acceleration applied to the sensor into a voltage signal ΔV. The voltage signal ΔV is an output differential voltage of the CV conversion amplifier. The output of the operational amplifier 3a of the CV conversion amplifier is connected to the positive phase input terminal of the A / D converter 7 via the filter 6a, and the output of the operational amplifier 3b is connected to the negative phase input terminal of the A / D converter 7 via the filter 6b. Is done. Thereby, the output differential voltage of the CV conversion amplifier is converted into a digital value by the A / D converter 7.

The output of the A / D converter 7 is subjected to demodulation processing and PID control based on the carrier clock 40 in the digital control unit 8 and outputs a 1-bit digital signal D _CTRL . The high voltage circuit 9 includes a 1-bit D / A converter that converts the digital signal D _CTRL into an analog voltage. The servo clock φ _SV and the inverted servo clock φ _SVB generated by the high-voltage circuit 9 are applied to the fixed electrodes of the MEMS capacitors 1e and 1f for servo control, so that the weights are detected MEMS capacitors 1a, 1b, The initial position is controlled substantially by a servo force (electrostatic force) in the direction opposite to the acceleration detected in 1c and 1d.

The earthquake information transmitting / receiving unit 2 receives the earthquake information from the repeater 102. The earthquake information transmitting / receiving unit 2 transmits the position information of each sensor from a GPS unit (not shown). The microcomputer 10 outputs a digital signal _DRDAC for changing the setting of the resistor D / A converter provided in the high voltage circuit 9. An example of the resistor D / A converter is shown in FIG. The resistance D / A converter includes resistance elements 200a, 200b, 200c, 200d, and 200e, switches 210a, 210b, 210c, 210d, and 210e, and switches 211a, 211b, 211c, 211d, and 211e.

The high-side output terminal 220 is selected based on the digital signal _DRDAC as V _H or a value obtained by resistance-dividing V _H and V _L. Similarly, the low-side output terminal 221 is selected based on the digital signal _DRDAC as a value obtained by resistance-dividing V _L or V _H and V _L. As a result, 'the reference voltage for the high side of 1bitD / A converter 222 to _H, V' V with _L as the reference voltage of the low side to adjust the dynamic range of the servo power. As a result, an appropriate dynamic range can be set for each sensor based on the earthquake information, and power consumption can be reduced.

Next, the configuration of the sensor of Example 2 will be described with reference to FIG.
In the second embodiment, the operational amplifiers 3 a and 3 b used in the pseudo differential CV conversion amplifier of the first embodiment are replaced with a fully differential operational amplifier 30. In this case, the output common-mode voltage level V _CMO (= (V _OUTP + V _OUTN ) / 2 of the fully differential operational amplifier 30, where V _OUTP and V _OUTN are respectively the positive phase output voltage and the reverse of the fully differential operational amplifier 30. A common mode feedback circuit (CMFB) is often provided to control the phase output voltage) to a desired voltage level (eg, V _DD / 2). Therefore, when a fully differential operational amplifier is used, the output common-mode voltage level V _CMO can be set near V _DD / 2.

  In the second embodiment, the sensor includes a fully differential CV conversion amplifier, which analyzes and combines the sensor position information transmitted from the sensor and the earthquake control information held by the data center to adjust the dynamic range of the sensor. is there. The configuration of FIG. 6 is the same as that of the first embodiment except that the sensor includes a fully differential CV conversion amplifier.

Next, the configuration of FIG. 6 will be described.
The capacitive MEMS 1 includes four detection MEMS capacitive elements 1a, 1b, 1c, and 1d. In order to perform servo control, two servo control MEMS capacitance elements 1e and 1f are further provided.

  From the first pair of detection MEMS capacitive elements 1a and 1b, the second pair of detection MEMS capacitive elements 1c and 1d, and the servo control MEMS capacitive elements 1e and 1f Each of the third pair structures is designed to be as identical as possible.

The movable electrodes of the detection MEMS capacitive elements 1 a, 1 b, 1 c, and 1 d are connected to first and second input terminals of a fully differential operational amplifier 30. On the other hand, the fixed electrodes of the detection MEMS capacitive elements 1a, 1b, 1c, and 1d are connected to the carrier clock φ _CP , the inverted carrier clock φ _CPB , the inverted carrier clock φ _CHB , and the carrier clock φ _CP generated by the high-voltage circuit 9, respectively. Has been.

A fixed voltage V _SVB is applied to the movable electrodes of the servo control MEMS capacitive elements 1e and 1f. On the other hand, the fixed electrodes of the MEMS capacitor elements 1e and 1f for servo control are connected to the servo clock φ _SV and the inverted servo clock φ _SVB generated by the high voltage circuit 9, respectively.

Between the first and second input terminals and the output terminal of the fully differential operational amplifier 30, feedback capacitive elements 4a (capacitance value C _F ), 4b (capacitance value C _F ) and resistance element 5a (resistance value R _{F), respectively.} ), 5b (resistance value R _F ).

  The first and second outputs of the fully differential operational amplifier 30 are connected to the first and second inputs of the common-mode detection circuit 31. The in-phase detection circuit 31 is a circuit that outputs an average voltage value of two output voltages of the fully differential operational amplifier 30. The output of the common-mode detection circuit 31 is connected to the non-inverting input terminal of the operational amplifier 32. The feedback circuit composed of the common-mode detection circuit 31 and the operational amplifier 32 constitutes the common mode feedback circuit (CMFB) described above.

  In the configuration of FIG. 7, unlike the configuration of FIG. 6, switches 20a and 20b are provided between the first and second input terminals and the output terminal of the fully differential operational amplifier 30 instead of the resistance elements 5a and 5b. For this reason, a signal for driving the switch is required. While the configuration of FIG. 6 continuously detects a change in capacitance as a change in voltage, the configuration in FIG. 7 differs in that the change in capacitance is sampled and held as a change in voltage.

In the fully differential operational amplifier, since the fluctuation of the average output voltage becomes a problem of the amplification operation due to element mismatch or the like, it is necessary to include the CMFB described above. CMFB detects an average output voltage in phase detecting circuit 31, such as a resistive divider, the voltage difference between the average output voltage and the reference voltage V _'B is amplified using an operational amplifier 32. Creating a negative feedback by inputting the differential voltage V _CM to the gate of the fully differential operational amplifier 30 the tail current source to control the output common mode voltage level V _CMO fully differential operational amplifier 30 so as to keep constant.

Further, the first and second outputs of the fully differential operational amplifier 30 of the CV conversion amplifier generate balanced differential outputs with respect to V _CMO . The differential output is connected to the differential input terminal of the A / D converter 7 via the filters 6a and 6b. The A / D converter 7 uses differential inputs to remove common mode noise and interference.

Next, the operation of the circuit of FIG. 6 will be described.
The movable electrode of the detection MEMS capacitive element 1a, the movable electrode of the detection MEMS capacitive element 1b, the movable electrode of the detection MEMS capacitive element 1c, and the movable electrode of the detection MEMS capacitive element 1d are mechanically moved so as to move together. And mechanically functions as a single weight (mass body). When a signal such as acceleration is not applied to the sensor, a force such as an inertial force does not act on the weight. Therefore, the weight, that is, the movable electrode of the detection MEMS capacitive element 1a and the movable electrode of the detection MEMS capacitive element 1b The movable electrode of the detection MEMS capacitive element 1c and the movable electrode of the detection MEMS capacitive element 1d are located at an initial location.

  When a signal such as acceleration is applied to the sensor, the weight receives a force such as an inertial force proportional to the signal such as acceleration, whereby the weight, that is, the movable electrode of the detection MEMS capacitive element 1a and the detection MEMS. The positions of the movable electrode of the capacitive element 1b, the movable electrode of the detection MEMS capacitive element 1c, and the movable electrode of the detection MEMS capacitive element 1d are integrally displaced in proportion to a signal such as acceleration. Thereby, when the movable electrode of the detection MEMS capacitive element 1a is displaced so as to approach the fixed electrode of the detection MEMS capacitive element 1a, the movable electrode of the detection MEMS capacitive element 1b is fixed to the detection MEMS capacitive element 1b. Move away from the electrode by the same amount of displacement.

  When the movable electrode of the detection MEMS capacitive element 1a is displaced away from the fixed electrode of the detection MEMS capacitive element 1a, on the contrary, the movable electrode of the detection MEMS capacitive element 1b becomes the fixed electrode of the detection MEMS capacitive element 1b. From the same distance. Similarly, when the movable electrode of the detection MEMS capacitive element 1c is displaced so as to approach the fixed electrode of the detection MEMS capacitive element 1c, conversely, the movable electrode of the detection MEMS capacitive element 1d is fixed to the detection MEMS capacitive element 1d. Move away from the electrode by the same amount of displacement.

  When the movable electrode of the detection MEMS capacitive element 1c is displaced away from the fixed electrode of the detection MEMS capacitive element 1c, conversely, the movable electrode of the detection MEMS capacitive element 1d becomes the fixed electrode of the detection MEMS capacitive element 1d. From the same distance. If the change in capacitance value due to the amount of displacement, that is, the change in electrode plate spacing is ΔC, the capacitance values of the detection MEMS capacitive elements 1a and 1c are C + ΔC, and the capacitance values of the detection MEMS capacitive elements 1b and 1d are C−ΔC. Become.

FIG. 5 shows waveforms of the carrier clock 40, the inverted carrier clock 41, and the clock signal 42 used in the second embodiment. Each clock is generated by the high voltage circuit 9. In the clock signal 42, the switch 20a and the switch 20b are turned on when a high potential signal (for example, V _DD ) is input and turned off when a low potential signal (for example, GND) is input.

  During the operation of the sensor, the CV conversion amplifier converts a MEMS capacitance change ΔC caused by a signal such as acceleration applied to the sensor into a voltage signal ΔV. The voltage signal ΔV is an output differential voltage of the CV conversion amplifier. The first output of the fully differential operational amplifier 30 of the CV conversion amplifier is connected to the positive phase input terminal of the A / D converter 7 through the filter 6a, and the second output of the fully differential operational amplifier 30 is connected to the A through the filter 6b. Connected to the negative phase input terminal of the / D converter 7. Thereby, the output differential voltage of the CV conversion amplifier is converted into a digital value by the A / D converter 7.

The output of the A / D converter 7 is subjected to demodulation processing and PID control based on the carrier clock 40 in the digital control unit 8 and outputs a 1-bit digital signal D _CTRL . Here, PID control (Proportional-Integral-Differential Controller, PID Controller) is a kind of feedback control, and the input value is controlled by three elements: deviation between output value and target value, integration thereof, and differentiation. It is a method.

The high voltage circuit 9 includes a 1-bit D / A converter that converts the digital signal D _CTRL into an analog voltage. The servo clock φ _SV and the inverted servo clock φ _SVB generated by the high-voltage circuit 9 are applied to the fixed electrodes of the MEMS capacitors 1e and 1f for servo control, so that the weights are detected MEMS capacitors 1a, 1b, The initial position is controlled substantially by a servo force (electrostatic force) in the direction opposite to the acceleration detected in 1c and 1d.

The earthquake information transmitting / receiving unit 2 receives the earthquake information from the repeater 102. The earthquake information transmitting / receiving unit 2 transmits the position information of each sensor from a GPS unit (not shown). The microcomputer 10 outputs a digital signal _DRDAC for changing the setting of the resistor D / A converter provided in the high voltage circuit 9. An example of the resistor D / A converter is shown in FIG. The resistance D / A converter includes resistance elements 200a, 200b, 200c, 200d, and 200e, switches 210a, 210b, 210c, 210d, and 210e, and switches 211a, 211b, 211c, 211d, and 211e. The high-side output terminal 220 is selected based on the digital signal _DRDAC as V _H or a value obtained by resistance-dividing V _H and V _L.

Similarly, the low-side output terminal 221 is selected based on the digital signal _DRDAC as a value obtained by resistance-dividing V _L or V _H and V _L. As a result, the dynamic range of the servo force is adjusted using V ′ _H as the high-side reference voltage of the 1-bit D / A converter and V ′ _L as the low-side reference voltage of the 1-bit D / A converter. As a result, an appropriate dynamic range can be set for each sensor based on the earthquake information, and power consumption can be reduced.

  The CV conversion amplifier and the capacitive sensor shown in the above embodiment detect, for example, acceleration and angular velocity, and output sensor output signals corresponding to them. This sensor output signal can also be used in systems such as automobiles, motorcycles, and agricultural machines that control attitude, ensure running stability, prevent skidding, etc., such as ESC (Electronic Stability Control) and sensor systems for resource exploration. is there.

1 Capacitive MEMS
2 seismic information transmission / reception unit 3 operational amplifier 4 feedback capacitive element 5 resistance element 6 filter 7 A / D converter 8 digital control unit 9 high voltage circuit 10 microcomputer 20 switch 30 fully differential operational amplifier 31 in-phase detection circuit 32 operational amplifier 40 carrier clock 41 Inverted carrier clock 42 Clock signal 100 Data center 101 Seismic vehicle 102 Repeater 103 Sensor 200 Resistor 210 Switch 211 Switch 222 1-bit D / A converter 1000 Control unit 1001 Sensor information receiving unit 1002 Seismic vehicle information receiving unit 1003 Table 1004 Sensor information Transmitter 1005 Earthquake vehicle information transmitter

Claims (15)

A seismic device;
A data center connected to the seismic device;
A repeater connected to the data center;
First and second sensors connected to the repeater;
The data center is
Based on the seismic information of the seismic device and the position information of the first and second sensors, the first dynamic range set for the first sensor and the first set for the second sensor. A subsurface exploration system characterized in that a second dynamic range different from the dynamic range is obtained and transmitted to each of the first and second sensors via the repeater. The first and second sensors are servo sensors.
The first sensor sets a first servo voltage value based on the first dynamic range transmitted via the repeater,
2. The underground exploration system according to claim 1, wherein the second sensor sets a second servo voltage value based on the second dynamic range transmitted via the repeater. The first and second sensors and the seismic device each have a GPS function,
2. The underground exploration system according to claim 1, wherein the seismic device includes a seismic vehicle or a dynamite. The data center is
It has a sensor information receiver, a seismic information receiver, and a controller.
The sensor information receiving unit receives the position information from the first and second sensors via the repeater,
The earthquake information receiving unit receives position information of the earthquake device from the earthquake device,
The controller is
The positional relationship between the position information of the seismic device and the positional information of the first and second sensors is obtained, and the first dynamic range set in the first sensor based on the positional relationship; 2. The underground exploration system according to claim 1, wherein the second dynamic range set in the second sensor is obtained. The first sensor is disposed between the seismic device and the second sensor;
5. The underground according to claim 4, wherein the control unit sets the first dynamic range of the first sensor to a value larger than the second dynamic range of the second sensor. Exploration system. The controller is
The first dynamic range value is increased during the period when the direct wave due to the seismic operation of the seismic device is expected, and the first dynamic range value is decreased after the direct wave arrives. 6. The underground exploration system according to claim 5, wherein control is performed as follows. The data center further includes a seismic information transmission unit,
The earthquake device causes vibration in an underground structure based on the earthquake information transmitted from the earthquake information transmitter.
5. The underground exploration system according to claim 4, wherein the first sensor and the second sensor detect a reflected wave from a boundary surface of the underground structure due to the vibration generated by the seismic device. The servo type sensor is
First, second, third and fourth detection capacitors;
First and second servo capacities;
First and second feedback capacitors;
A CV conversion circuit for obtaining a voltage based on capacitance values of the first feedback capacitor and the second feedback capacitor;
First and second filters for removing a low-frequency band from the output signal of the CV conversion circuit;
An AD converter that obtains a digital signal by converting the input voltage from analog to digital;
A digital control unit for performing PID control using the digital signal as an input;
A high voltage circuit for increasing the voltage of the output signal of the digital control unit;
An earthquake information transmitting and receiving unit for receiving the earthquake control information from the repeater;
An output signal is received from the earthquake information transmitter / receiver, a reference voltage of the high voltage circuit is controlled, the first servo voltage value is set in the first sensor, and a second servo is set in the second sensor. The underground exploration system according to claim 2, further comprising a microcomputer that sets a voltage value. The CV conversion circuit is a pseudo-differential CV conversion amplifier including a first operational amplifier and a second operational amplifier,
A signal reflecting capacitance values of the first detection capacitor and the second detection capacitor is input to the inverting input terminal of the first operational amplifier,
A signal reflecting the capacitance values of the third detection capacitor and the fourth detection capacitor is input to the inverting input terminal of the second operational amplifier,
A fixed voltage is input to the non-inverting input terminals of the first and second operational amplifiers,
The output of the first operational amplifier is input to the first filter,
The output of the first filter is input to a first input terminal of the AD converter, and the output of the second operational amplifier is input to the second filter,
The output of the second filter is input to a second input terminal of the AD converter,
The AD converter outputs digital data with the outputs of the first and second filters as inputs,
The digital signal is input to the digital control unit,
The digital control unit performs PID control based on the digital signal,
9. The underground exploration system according to claim 8, wherein the first and second outputs of the digital control unit are connected to the high voltage circuit as signals that are inverted from each other. The high voltage circuit is:
It has a resistance type DA converter and a 1-bit DA converter,
Controlling the first and second output voltage values of the DA converter based on a control signal from the microcomputer;
The 1-bit DA converter uses the first and second output voltage values as first and second reference voltages,
The 1-bit DA converter performs a switching operation based on an output signal of the digital control unit with the first reference voltage as a high-side voltage and the second reference voltage as a low-side voltage. The underground exploration system according to claim 9. The CV conversion circuit includes:
A fully differential CV conversion amplifier,
A signal reflecting the capacitance values of the first detection capacitor and the second detection capacitor is input to the first input terminal of the fully differential CV conversion amplifier,
A signal reflecting the capacitance values of the third detection capacitor and the fourth detection capacitor is input to the second input terminal of the fully differential CV conversion amplifier,
A common mode feedback circuit including a common-mode detection circuit;
The common mode feedback circuit feedback-controls the average voltage value of the first and second outputs of the fully differential CV conversion amplifier to the fully differential CV conversion amplifier,
A first output of the fully differential CV conversion amplifier is input to the first filter;
The output of the first filter is input to a first input terminal of the AD converter, and the second output of the fully differential CV conversion amplifier is input to the second filter,
The output of the second filter is input to a second input terminal of the AD converter,
The AD converter outputs digital data with the outputs of the first and second filters as inputs,
The digital signal is input to the digital control unit,
The digital control unit performs PID control based on the digital signal,
9. The underground exploration system according to claim 8, wherein the first and second outputs of the digital control unit are connected to the high voltage circuit as signals that are inverted from each other. The high voltage circuit is:
It has a resistance type DA converter and a 1-bit DA converter,
Controlling the first and second output voltage values of the DA converter based on a control signal from the microcomputer;
The 1-bit DA converter uses the first and second output voltage values as first and second reference voltages,
The 1-bit DA converter performs a switching operation based on an output signal of the digital control unit with the first reference voltage as a high-side voltage and the second reference voltage as a low-side voltage. The underground exploration system according to claim 11. The first feedback capacitor and the second feedback capacitor have substantially the same capacitance value,
The first and second electrodes of the first feedback capacitor are respectively connected to the first input and the first output of the CV conversion circuit directly or through a switch,
9. The first and second electrodes of the second feedback capacitor are respectively connected to a second input and a second output of the CV conversion circuit directly or through a switch. The underground exploration system described in 1. Further comprising first and second feedback resistors;
The first feedback resistor and the second feedback resistor are resistor element pairs having substantially equal resistance values,
The first and second terminals of the first feedback resistor are connected to the first input terminal and the first output terminal of the CV conversion circuit, respectively.
The basement according to claim 13, wherein the first and second terminals of the second resistance element are connected to a second input terminal and a second output terminal of the CV conversion circuit, respectively. Exploration system. A first switch and a second switch;
The first and second terminals of the first switch are connected to a first input terminal and a first output terminal of the CV conversion circuit, respectively.
The underground exploration according to claim 13, wherein the first and second terminals of the second switch are respectively connected to a second input terminal and a second output terminal of the CV conversion circuit. system.

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