• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
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    • 专利摘要:
    magnetic compensation circuit; compensator active electromagnetic prospecting system; plywood receiver; method for compensating the output of a magnetic sensor a solution for compensating a magnetic field sensor to allow detection of a small magnetic field in the presence of a large magnetic field is revealed. a magnetic field sensor detects the magnetic field which produces an analog signal then encoded by an analog to digital converter (adc) into a digital stream. a controller operating on the digital stream incorporates additional sensor information to create the compensation signal that is sent to a digital-to-analog converter (dac). this compensation signal then modifies the magnetic field sensor output before entering the adc. compensation is software controlled, and adaptable to numerous conditions that require compensation. apart from being easily tunable, the compensation must dynamically respond to changing conditions. the invention has particular application to aerial electromagnetic monitoring where small diffuse earth fields are measured in the presence of a large transmitted field.
    公开号:BR112015023235B1
    申请号:R112015023235-3
    申请日:2014-03-20
    公开日:2022-02-01
    发明作者:Benjamin David Polzer；Gordon Fox West；Peter Whyte Walker
    申请人:Vale S/A；
    IPC主号:
    专利说明:

    field of invention
    [001] The present invention relates generally to the measurement of magnetic fields, and in particular to methods and apparatus for accurately detecting the presence of a stray and Weak magnetic field in the presence of a known stronger magnetic field. In particular, embodiments of the present invention relate to improved methods of geophysical electromagnetic monitoring. Related Art Description
    [002] Removing the effect of a known but undesired magnetic field on a sensor is generally known as compensation, and sometimes referred to as bucking. Compensation can be considered to have two distinct forms. In the first form, sometimes called active bucking, a primary magnetic field is canceled over a volume of space by creating a secondary magnetic field that is in opposition to it. In the second form of compensation, sometimes called passive bucking, the effect of a magnetic field detected by a sensor is canceled by adding a voltage to the sensor output that is opposite to the sensor output.
    [003] There may be several reasons for wanting to remove a large magnetic field signal from a magnetic sensor. In particular, by removing a large part of the signal, thereby reducing the signal measured by the sensor, the effective dynamic range of the sensor can be increased, thus allowing for field amplification and resolution that would not be possible otherwise. Additional reasons may include improved linearity and reduced rate of change of related noise. Furthermore, if the compensation causes the magnetic fields in the vicinity to be reduced, there may be a corresponding reduction in noise caused by current induction of swirls and induced magnetization in nearby metallic components.
    [004] For the purposes of this invention, a magnetic sensor (H) may be a magnetometer, as exemplified by a SQUID, a feedback coil, a fluxgate, an atomic vapor sensor, or similar device that is directly sensitive to the magnetic field. , or a coil, loop or similar electrical circuit element, which by virtue of Faraday's law is sensitive to time changes in magnetic flux density, or any instrument with similar functionality.
    [005] Compensation methods have found their way into a diverse number of applications, one of which is the suppression of transmitted electromagnetic energy. For example, in GB 2438057A to Robertson, transmission of electromagnetic radiation by a magnetic sensor is suppressed. In another example, Paschen et al reveals how to suppress transmission line noise at US 5,920,130A. In a third example, Holmes and Scarzello use a set of three orthogonal Helmholtz coils to attach an electrical device to US 6,798,632 B1, also to suppress emitted energy frequency radiation.
    [006] Compensation methods can also be used to control noise from magnetic fields within a volume, and it is common for rooms to contain magnetic resonance imaging devices or electron beams. In these cases, the current sent by the Helmholtz coils surround a volume to be shielded. Compensation is usually achieved by positioning a magnetic sensor within the shielded volume, the signal of which is then used to generate a current in the coils and thus nullify the field in the sensor. This method is employed in document US5465012A to Dunnam, which uses three sets of orthogonal Helmholtz coils to compensate for a uniform magnetic field inside the coils, as Kropp et al. . Buschbeck et al, in US 2005/0195551, note that in some applications involving particle beams, it is difficult to position the sensor in the volume where the field must be nullified, so two sensors, positioned at two points, are used to interpolate the value. field to be cancelled. Gelbien in US 5,952,734 discloses an apparatus for maintaining a constant magnetic flux in a region by employing a coil energized by a servo loop and controlled by a flux lock circuit and a magnetic sensor. A compensation method employing both coils and a magnetically shielded room has been proposed by Buchannan in US 2004/0006267. Wallauer in EP 2259081A1 proposed a method of magnetic field compensation with a magnetoresistive sensor sensing the field inside the Helmholtz coils. Wallauer's invention divides the incoming magnetic field signal into complementary high and low frequency components, with the low component passing through an analog to digital converter (ADC), a digital filter, and then a digital to analog converter (DAC). ) before being recombined with the high-frequency component and passed through the Helmholtz coils.
    [007] Farjadad is document US 2011/0292977 discloses an ethernet-based compensation circuit for profiling applications in which a common-mode signal is input to a controller to generate a compensation signal for application to a different signal. The purpose of the invention is to pre-compensate the differential signal to reduce effect or noise interference or imbalance in the communication channels.
    [008] In the field of geophysical measurement, where the Earth's conductivity structure is deduced from electromagnetic field (EM) measurements, compensation methods are common. A predominant example of this compensation is found in an active source electromagnetic prospecting system. In an active EM system, a transmitter energizes a loop or coil with a periodic (constantly repeating) time-varying current. This current creates an electromagnetic field, typically referred to as a "primary" field, which energizes the flow of current within the Earth.
    [009] This Earth current creates a "stray" electromagnetic field that is detected by a receiver attached to the EM system. In many EM systems, the transmitter and receiver are geographically configured so that the primary field is orders of magnitude greater than the stray field. In such cases, it is advantageous to employ compensation methods to remove as much of the primary field from the sensors as possible allowing smaller stray fields to be detected.
    [0010] In many active source systems, compensation is implemented by achieving a balance between the primary and secondary fields created by a bucking coil. In doing so, the field network of the two fields can be approximately zeroed out at the sensor.
    [0011] Accurate balancing of the bucking with the primary field is best achieved when the geometry of the coils is achieved, as this also fixes the inductances between the transmitter and the bucking coils, and their coupling to the volume where the fields will be cancelled. With the coil geometry fixed, precise single-point compensation can be achieved by positioning the bucking coils in a series circuit with the transmission coil and adjusting the moments of the respective coils so that the magnetic fields are in the exact position. This approach works best in cases where the fields are not significantly disturbed by other sources of scattering, and where the coil geometry is rigid. It is particularly effective when the transmitter and bucking coils are in series and therefore have the same waveform current, at least at frequencies well below those whose coil capacitance significantly influences the load impedance.
    [0012] An example of compensation is provided by Davydychev et al, who disclose an apparatus for adjusting the mutual inductance of a transmitter and receiver coil in US 2010/0026280, both with a bucking coil and with a trim coil. The trim coil is included to allow the bucking coil field to be adjustable, improving the null quality that can be achieved. Another example is seen in the field of soil geophysical measurement, where Bosnar in US 2009/0295391 A1 discloses an instrument for simultaneously measuring the static magnetic field and the time-varying electromagnetic (EM) response of the soil. Bosnar uses a rigid geometry in which a Helmholtz-type compensation coil is used to nullify the time-varying primary electromagnetic field in a magnetometer used to detect the static magnetic field of the Earth.
    [0013] For the reasons cited above, compensation is generally required in aerial electromagnetic measurement (AEM) where a source-controlled transmitter loop is employed. An example of an AEM system employing compensation is provided in US 2010/0052685 to Kuzmin and Morrison, which discloses a flexible AEM apparatus, marketed as a VTEM AEM system. In the VTEM system, concentric transmitter and bucking coils are centered on a receiver. Bucking is also used in the Aerotem AEM system, where a rigid geometry is employed, with compensation in the latter AEM system tending to be more effective than the former due to the rigid coil geometry used. The more stable bucking system of AeroTem versus VTEM is then obtained at the cost of extra weight, implying greater expense, and a larger frame that is more expensive to ship and repair when damaged. A means of precisely compensating a system with flexible geometry would be an advantage.
    [0014] The primary field bucking discussed above allows the electromagnetic receiver to be operated at greater gain than would otherwise be possible in the absence of compensation, and allows the Earth's stray fields to be measured with greater sensitivity. Even so, compensation systems employed in the current state of the art in AEM methods compensate only the primary field of the transmitter. Yet there are other strong sources of magnetic field variation in various forms of noise that also degrade measurement quality and limit receiver gain. These include the effect of the magnetic sensor's rotation on the Earth's static magnetic field, radiated energy from power lines and cultural sources, and spherical noise. In cases where an EM system is mounted on a metallic vehicle, such as the GEOTEM AEM system, or where EM measurements are taken close to the large conductor, such as at sea, or in a mine in the presence of conductivity and/or permeable ores or infrastructure , compensation that can dynamically respond to the changing conductivity environment would be an advantage.
    [0015] An additional effect that occurs in some AEM systems operating in the time domain occurs as the transmitter current waveform can take a finite time to propagate through the transmitter loop, an effect that can be noticeable at the receiver when the loop is quickly energized with current. In these cases, the current in a compensation coil mounted in series with the transmitter coil cannot be in phase with the current(s) in the transmitter loop(s) and therefore may need correction.
    [0016] While bucking coils are intended to increase the quality of AEM survey data, these same coils can act as antennas and thus receive and retransmit sources of background noise, creating an additional source of noise in the AEM dataset. More noise can be caused by the change in coil engagement with respect to the Earth's static field. Such considerations should not be a factor where the bucking field exactly opposes the primary field at frequencies low enough that coil capacitances are not a factor. However, in practice this exact cancellation is difficult to achieve and there must be an uncanceled residual signal as a result, particularly in systems that are not rigid. It would therefore be advantageous to have a small, compact bucking system that could respond to such effects.
    [0017] Furthermore, in an AEM system like the one proposed by Polzer in WO 2011/085462, where the receiver is on an isolated motion platform, the receiver can translate or rotate with respect to the transmitter, so standard approaches to bucking that override the primary field at a singular point may be ineffective. In such cases, it would be advantageous to separate the loop compensation system from the transmitter and position it with the receiver. It is more beneficial in this case to create a digital bucking signal based on the information sent to the wireless receiver module rather than relying on an analog serial configuration. Such a configuration would be difficult to implement for this system as a direct electrical connection, as the direct connection would interfere with motion isolation. Summary of the invention
    [0018] According to the present invention, a magnetic field compensation system for suppressing the effect of a large magnetic field on a magnetic sensor is provided, or its output, in order to allow detection with greater sensitivity of small variations in the field. , called here "compensator". The invention uses digital signal process to predict the compensation to be applied. A magnetic sensor detects a magnetic field as an analog signal, which is then digitally encoded by an analog to digital converter (ADC). This signal is read by a controller and the time is recorded. The controller then transmits these signals to an information processing computer for processing and storage. The processing computer develops a prediction of the future compensation waveform into a model that includes data received from the controller. The computer passes the predicted waveform back to the controller. The controller generates an output digital compensation signal (amplitude as a function of time) that is sent to the digital-to-analog converter (DAC) where it is converted to analog format. The analog output signal from the DAC generates the compensation signal that suppresses the effect of the larger magnetic field, either directly at the magnetic sensor or at its output.
    [0019] In some embodiments, additional sensor inputs can be used to assist in predicting the compensation signal. In these embodiments, the controller timestamps the sensor input data and transmits it to a data processing computer for processing and storage. These additional (or auxiliary) sensor inputs are used by the data processing computer in conjunction with the above inputs to develop the predicted waveform. In cases where the primary magnetic field created by the transmitter of an electromagnetic prospecting system must be compensated for, auxiliary sensor data may refer to the shape and amplitude of the transmitter current waveform, and the geometric configuration of the transmitter loop.
    [0020] In one such embodiment of the present invention, the compensation signal is added to the analog output of the sensor to suppress the unwanted large magnetic field analog signal before it is digitized, thus improving the sensitivity of the DAC.
    [0021] In a second embodiment, the compensation current drives current to a coil which is then used to suppress unwanted large magnetic field variation in the sensor, thus allowing the smaller field to be detected.
    [0022] In either embodiment, the signal inputs may include data streams emanating from auxiliary sensors from which compensation for the larger magnetic field can be predicted. Sensors may include a transmitter waveform monitor, sensor coil and geometry and displacement monitors, a camera, a magnetometer, an induction coil, an angular rate sensor, an accelerometer, an inclinometer, and a GPS or other means of geolocation instrumentation. This sensor data, as well as the data stream from the compensated magnetic sensor itself, can form the input data whose predictive or filter model can be used to compute and thus suppress the effect of a large magnetic field. Compensation can be applied to the primary field of an electromagnetic transmitter, but can also be applied to other effects such as power line magnetic fields. A key feature of the invention is that it can use a software predictive model with input from sensors to adaptively compensate for magnetic field measurements when conditions permit.
    [0023] The present invention is to be deployed as a receiver of an electromagnetic prospecting system by mounting it in a suitable cabinet along with a power source and optionally with auxiliary sensors to provide geolocation, orientation and other data as may be required. Where a transmitter is not present, the present invention may then be employed as a passive electromagnetic receiver where power line noise or rotational motion effect can be compensated for. Where a transmitter is present, the present invention can compensate for the primary field transmitter. This can be done either by passively monitoring the waveform current output by the transmitter, or by monitoring the waveform of the transmitter which actively sends waveform control information to the transmitter.
    [0024] The invention has several aspects that represent improvements in the current state of the craft. In geophysical prospecting, the invention is applicable to active EM methods where primary field compensation in general is of paramount importance, and to passive EM methods where compensated data can be acquired on mobile platforms or in the presence of power line noise.
    [0025] With regard to geophysical prospecting applications, the present invention has the advantage of being largely independent of the system hardware. By providing suitable sensor inputs with a predictive model, for example, the invention can be applied to aerial electromagnetic (AEM) systems having flexible geometry. The predictive model can be a neural network trained or formed while the AEM system is removed from the Earth scattering effect. Predictive capability can also be employed to provide compensation that matches the positions of aircraft surface controls. The predictive element is also important when compensating for a periodic primary waveform, as computer processing latencies in applying the compensation signal can be accommodated with delays of one or more periods of the primary waveform. A predictive model can include inert, dynamic, and kinematic sensor inputs to predict the signal caused by the rotation of a sensor in the Earth's static magnetic field.
    [0026] Another advantage of the invention is that compensation can be made on a platform that is mechanically independent of the transmitting antenna, allowing compensation on platforms designed for motion isolation, an example of what is provided by Polzer et al in the WO 2011/ 085462. By digitally connecting the compensated sensor to the controller, the sensor can be positioned away from the controller, peripheral devices, and any noise they make. In so doing, the space and power requirements of the compensated sensor are also minimized, finally, compensation can be made available at very low power levels such as supplied by battery systems, allowing use on platforms where large amounts are not available.
    [0027] A further aspect of the invention is that the dynamic range of the measurement system is extended by taking advantage of the intrinsically higher fidelity of DACs compared to ADCs by subtracting an analog waveform created by the predictive model of the magnetic field. In the case where the signal to be compensated is periodic, the compensation signal must be provided with a controlled latency so that the compensation signal can be fed back precisely in one cycle, or a number of cycles, of delay. The compensation signal as well as the compensated signal are recorded and the time is recorded together with the peripheral sensor data on which the compensation signal is modelled. The uncompensated signal must then be computed from these registers. Brief Description Of The Drawings
    [0028] Figure 1 shows an embodiment of the invention implemented for a simple magnetic sensor. Lines marked with a slash denote conduit for digital data; arrows indicate the direction of signal propagation;
    [0029] Figure 2 shows an embodiment of the invention configured to receive data from the three magnetic sensors;
    [0030] Figure 3 shows how the invention can be configured to compensate for the primary field of a controlled source of EM waveform;
    [0031] Figure 4 shows how the invention can be implemented in an EM system;
    [0032] Figure 5 illustrates another embodiment of the invention illustrated in Figure 1; and
    [0033] Figure 6 illustrates another embodiment of the invention illustrated in figure 1. Description of Preferred Embodiments of the Current Invention
    [0034] A preferred embodiment of the present invention, illustrated in Figure 1, provides compensation by means of adding analog signals. Figure 1 illustrates the magnetic sensor 100 that creates a signal output on the analog line 101 to one of the inputs of the adder 102. The adder 102 creates a signal that is sent on the analog line 103 where it is then converted to digital format by an Analog Converter to Digital (ADC) 104. The digital signal is output on digital link 105 to a controller 106. Controller 106 uses the digital signals input on digital links 105 and 112 to compute and send an offset digital signal on digital link 107 to a Digital to Analog Converter (DAC) 108 where it is converted to analog format. The digital signals on links 105 and 107 are also stored on storage device 114 via link 115 along with precise timing, allowing the uncompensated field to be reconstructed mathematically. The analog signal from DAC 108 is output via line 109 to become the second input to adder 102. Controller 106 also outputs the digital signal received on link 105 to a computer 11 via link 112.
    [0035] Where additional data needs to form a compensation signal, auxiliary analog or digital sensors 110 transmit the data to computer 111 for storage and use in computing the compensation signal. Computer 111 also updates the model by predicting the magnetic field at sensor 100 using inputs from controller 106 and sensors 110.
    [0036] Said computer 111 is adapted to produce a computational (or digital) model of the magnetic field using an algorithm that substantially predicts the expected value of the magnetic field based on the primary digital signal, the previous digital compensation signal, and any input data. auxiliary sensor, allowing compensations for the following effects commonly experienced in EM measurements, including but not limited to: • large, repetitive magnetic field from the transmitter loop, • the finite speed of light in a transmitter loop, • sensor rotation in the Earth's magnetic field, • the change in mutual inductance of the transmitter and receiver circuit, • variations in harmonic noise, for example due to power lines and electrical equipment, • large Earth response when an EM survey system is energized on or near the ground, • the seawater response, • the bottom response of an EM system mounted on a support containing metallic components, such as o: an aircraft, where the background response is measured as the system is removed from Earth, • the response of metallic machinery or metal parts, • the Earth's static magnetic field, • or any combination of the above.
    [0037] The resulting digital data is transmitted on digital link 112 to controller 106, and to data storage unit 114 via link 113.
    [0038] Magnetic sensor 100, adder 102, ADC 104, and DAC 108 constitute sensor package 150.
    [0039] Digital links 105, 107, 112, 112 and 115 may comprise a direct electrical connection, an optical connection, an infrared connection, a wireless connection or a combination thereof.
    [0040] In other embodiments of the current invention, additional magnetic sensors 100 may be added to controller 106 as required, and an embodiment of the current invention may include two, three or more magnetic sensors 100 configured in their respective sensor packages 150.
    [0041] Figure 2 shows the controller 106 configured to receive data from the three magnetic sensors 100a, 1000, 100c using three embodiments of the sensor package 150a, 150b and 150c. The 150a, 1500, and 150c sensor packages in Figure 2 have been configured to allow acquisition of three components of electromagnetic data.
    [0042] In the current state of the art, the accuracy obtainable from a DAC is approximately an order of magnitude more accurate than available from an ADC. Furthermore, the compensation signal provided by the DAC 108 is known to be more accurate compared to the signal that can be read from an ADC 104. Consequently, the analog signals on lines 101 and 109 can be approximately an order of magnitude greater than the output analog signal on line 103 without the loss of resolution on ADC 104.
    [0043] Providing digital links such as 105, 107, 112 and 115 allow the controller 106, the computer 111, or both to be located either remotely, or on separate platforms from the sensor 100. These features are advantageous as they remove the noise sensor associated with computing equipment and allows the 150 sensor package to be compact and lightweight. In such cases, the sensor package 150 may be physically separated from the other components of the present invention by employing wireless data transfer means. This feature is particularly advantageous where space and weight may be at a premium in the vicinity of the sensor.
    [0044] Therefore, the invention can be applied in electromagnetic drilling (EM) methods, where a sensor 100 can be positioned on the drill bit where space is at a premium, in aerial methods where the sensor must be mounted either on a drone or on a platform. motion isolator so that weight must be light, or on rotating equipment, in hazardous, explosive, or high pressure environments where the sensor package must be closed and mounted separate from the computer 111 and controller 106 for logistical, mechanical, and of security. In such cases, where a small sensor package 150 must be used, compensation can be provided via a digital link to communicate remotely with the controller 106 and any peripherals.
    [0045] Where strong primary fields can cause false signals due to induction by nearby metallic components or ground loops, compensation via digital link has the advantage of removing sensor 100 from these possible sources of noise, or from the noise induced or generated by the operation of the computing equipment itself.
    [0046] Figures 3 and 4 illustrate aspects of an embodiment of the invention for the case where it is used to compensate for the primary field in an active EM system. Figure 3 illustrates a compensated EM receiver 350, comprising the compensator. Figure 4 illustrates aspects of an embodiment of the invention in relation to a typical active EM source of a system. In the embodiment illustrated in Figures 3 and 4, the transmitter and the compensator are synchronized, but the synchronization of the two is not strictly necessary.
    [0047] The EM system illustrated in Figure 4 comprises an energizing current source 400 that sends current in cable 401 to energize transmitter 402. In one embodiment of the present invention, the transmitter accepts in-line control signals 301 from the EM receiver. compensated 350. Transmitter 402 emits a current in cable 403 to transmitter loop 404. Current flowing in loop 404 creates a magnetic field detected in magnetic sensors 100. Transmitter current is measured and transmitted on input line 302 to compensated receiver EM 350. In some embodiments of the present invention where the transmitter is not synchronized with the trim, neither or both lines 301 and 302 may not be necessary.
    [0048] Referring to the aforementioned embodiments in which the transmitter and the compensator are synchronized, the waveform timing information can be sent to the transmitter 402 (figure 4) via the output line 301 (figure 3) of the controller 106, which forms a part of compensated EM receiver 350. The resulting waveform current is sent to transmitter loop 404 where it is measured at input 302 by current-to-voltage converts 303. The resulting analog output output to output line 304 is then digitized by ADC 305. The resulting digitized signal is output to digital link 306 for processing by controller 106.
    [0049] In this embodiment, the current waveform can be averaged over several cycles to create an exemplary waveform that can be used to control the compensation output of controller 106. Thus, the compensation signal for the primary field can be predicted with a controlled latency so that by periodic signals the compensation signal can be fed back precisely with a delay cycle. The exemplary waveform can be used together with data from the auxiliary sensor, as well as provided by means of camera or reflectometer imaging, to provide a compensation signal adjusted for changes in the geometry of the EM system.
    [0050] It should be understood that aspects of the invention in which the current waveform is sent to the compensator may be configured differently than described above. For example, the information path carrying current waveform measurements to the computer via the sequence of inputs 302, 304, 306 to 112 can easily be replaced by inputs 110. There are numerous configuration modes of the invention for it to control and process. the digital inputs; the figures should be illustrative if some of the myriad of possibilities for configuration of the invention and should not limit the scope of the claims. For example, in another embodiment of the present invention, the transmitter must send waveform timing information directly to the EM compensated receiver.
    [0051] It is not absolutely necessary for the transmitter and compensated EM receiver to be synchronized. In another embodiment of the invention; missing signal line 301, the computer passively monitors the transmitter waveform from signal line 302 over line 112. Instead of using control line 301 to synchronize the period and phase of the current waveform with the compensator , the incoming waveform can be analyzed on the computer over a moving time window to establish the period and phase and a predicted waveform. The resulting predicted waveform can then be communicated to controller 106 which injects the offset signal at the computed synchronized time. Such a realization would be preferable as a push-button accessory to an existing EM system as it would allow compensation without any modification to the transmitter.
    [0052] In a related embodiment, neither lines 301 or 302 are present. Instead, the uncompensated signal can be analyzed over a moving time window to establish its period and phase rate and thus derive a predicted instantaneous waveform, for example using a balanced time average. The resulting predicted waveform can then be communicated to controller 106 which injects the offset signal at the computed synchronized time.
    [0053] In addition to auxiliary sensor inputs, provisions are made for acquiring geolocation data, such may be acquired by GPS, Glonas, laser, barometric, sonar and radar altimetry, or other instrumentation of similar purpose. Geolocation data is entered into computer 111 on data link 307, and then merged with the data stream to be exported on digital link 113.
    [0054] An independent or GPS signal can be used to provide synchronized timing information to the transmitter and compressor from an external source. In such an embodiment, synchronization of the transmitter and the compensator may be possible without the signal line 301.
    [0055] In another embodiment of the present invention, illustrated in Figure 5, the magnetic field feedback is used to compensate for the primary magnetic field in place of the feedback voltage. In this embodiment, sensor package 550 replaces sensor package 150, wherein a feedback coil 503 in a magnetic sensor 100 replaces the function of the feedback voltage provided by the adder 102. Instead of using feedback voltage in the adder, the magnetic sensor 100 creates a signal on analog line 101 which is then converted to digital format by ADC 104. The digital signal is output on digital link 105 to controller 106. Controller 106 uses digital input signals from digital links 105 and 112 to send a digital compensation signal over digital link 107 to DAC 108 where it is converted to analog format. The analog signal from DAC 108 on line 109 is then converted to current with a voltage-to-current converter 501. The resulting current flows in circuit 502, which comprises feedback coil 503. Current in feedback coil 503 compensates for the magnetic field at sensor 100 according to the digital signal emitted by controller 106 to digital link 107.
    [0056] The aforementioned embodiments of the invention are to be implemented as part of an electromagnetic prospecting system. They can be used to compensate for the rotation of the magnetic sensor in a static magnetic field, such as the Earth's magnetic field. In addition, the compensation model for the magnetic field can include the primary field effect and the sensor rotation effect, as well as any other magnetic field effects that may be required. Compensating for sensor rotation, auxiliary inputs may comprise an estimate of the total magnetic field, as may be provided by a fluxgate magnetometer or alternately, an estimate of the magnetic field from the International Geomagnetic Reference Field (IGRF), and any of the orientations of the sensor, such as may be provided by a gyroscope, attitude and heading reference system (AHRS) or instrument of similar functionality, or an angular rotation rate sensor, such as may be provided by accelerometer pairing. The mathematical theory for calculating the signal measured by a magnetic sensor rotating in the Earth's magnetic field is known in the current state of the art, an example is given in WO 2011/063510 A1 to Kuzmin and Dodds.
    [0057] Another embodiment of the invention is illustrated in figure 6. In this embodiment, the functions of controller 106 and computer 111 of figure 1 are merged with each other to become a single computer-controller 106/111. In so doing, digital links 112 and 113 become superfluous, sensor input 110 and 307 interact directly with computer-controller 106/111, and digital link 115 acquires the additional function of digital link 113.
    [0058] In another embodiment of the invention, the compensation may include power line fields as well as transmitter current waveform. In yet another embodiment of the present invention, inputs may be from sensors detecting the motion of moving machinery or metallic parts, so as to provide efficient compensation for the magnetic field due to moving ferromagnetic and electrically conductive parts, such as may be found in industrial environments or on an aircraft.
    [0059] While the invention has been shown and described in terms of exemplary embodiments, it will be understood that this invention is not limited to these particular embodiments, and that many changes and modifications may be made without departing from the true spirit and scope of the invention as defined. in the attached claims.
    权利要求:
    Claims (14)
    [0001]
    1. An additive compensation magnetic circuit, comprising at least one sensor package (150) configured to output a primary digital signal, and a controller (106) configured to receive this primary signal, compute a digital compensation signal, and then sending this digital compensation signal to the sensor package (150), wherein this sensor package (150) comprises: a magnetic sensor (100) configured to create a primary analog signal by sensing a component of the magnetic field; a adder (102) configured to receive the primary analog signal and produce a secondary analog signal; an ADC (104) configured to convert this secondary analog signal to the primary digital signal; and a DAC (108) configured to convert this digital compensation signal into a tertiary analog signal to the adder (102), characterized in that the additive compensation magnetic circuit comprises a computer (111) configured to form a model of the predicted magnetic field digitally, wherein the controller (106) in the compensation circuit imports the primary digital signal, the digitally predicted magnetic field pattern, and outputs the digital compensation signal to the compensation circuit.
    [0002]
    2. A magnetic feedback compensation circuit, comprising at least one additive compensation magnetic circuit according to claim 1, characterized in that the magnetic sensor (100) is configured to detect the sum of a primary magnetic field with a compensating magnetic field created by a feedback coil (503) to create a primary analog signal; the sensor package (550) further comprising a feedback coil (503) through which a compensating current flows to form the compensating magnetic field over the volume occupied by the magnetic sensor; and a voltage to current converter (501) configured to receive the voltage to current which receives said current from the secondary analog signal and energizes the feedback coil (503) with the compensating current to create the compensating magnetic field emitted by the controller. (106).
    [0003]
    3. The magnetic compensation circuit according to any one of claims 1 or 2, characterized in that it further comprises a storage medium (114) that retains the primary digital signal, the digital compensation signal and the input data of an auxiliary sensor.
    [0004]
    4. The magnetic compensation circuit according to any one of claims 1 to 3, characterized in that the digitally predicted magnetic field model is computed in real time.
    [0005]
    5. The magnetic compensation circuit according to any one of claims 1 to 4, characterized in that the digitally predicted model of the magnetic field is computed from inputs to the controller (106) selected from the group of: a digital signal output primary by the magnetic compensation circuit, a digital compensation signal output by the controller (106) in the compensation circuit, AHRS output, angular rate transducer outputs, current monitoring outputs, static field magnetometer outputs, timer outputs and combinations thereof.
    [0006]
    6. An active compensator electromagnetic prospecting system comprising a magnetic compensation circuit according to any one of claims 1 to 5, characterized in that the current waveform of the transmitter in an electromagnetic prospecting system is measured by a current-to-voltage converter to produce an analog output signal, this analog signal being digitized by an ADC for input to the magnetic compensator controller.
    [0007]
    7. The active compensator electromagnetic prospecting system according to claim 6, characterized in that the magnetic compensator compensates for the transmitter's primary magnetic field.
    [0008]
    8. The active compensator electromagnetic prospecting system according to any one of claims 6 and 7, characterized in that the controller (106) on the magnetic compensator sends information in the form of waves to the transmitter
    [0009]
    9. A compensated EM receiver comprising a magnetic compensation circuit according to any one of claims 1 to 5, characterized in that the magnetic compensator is mounted in a transportable cabinet with a power source.
    [0010]
    10. The compensated EM receiver according to claim 9, characterized in that the ripple current from the transmitter in an electromagnetic prospecting system is measured by the current-to-voltage converter (303) to produce an analog output signal, such a signal analog being digitized by an ADC for input to the magnetic compensator controller.
    [0011]
    11. A method of compensating the output of a magnetic sensor (100) in response to the change in the primary magnetic field, comprising the steps of: A) measuring a component of magnetic field, to create the primary analog signal; B) creating of a secondary analog signal by summing the primary analog signal with a tertiary analog signal using an adder (102); C) converting the secondary analog signal into a primary digital signal with an ADC (104); D) inserting the primary digital signal into a controller (106) via digital links; E) computing a digital output signal with the controller (106), sending the output digital compensation signal via digital link; eF) converting the output digital compensation signal into a tertiary analog signal by a DAC (108), producing the tertiary analog signal to the adder (102); characterized by the fact that in step E a computer (111) uses the primary digital signal and an auxiliary input sensor to form a digitally predicted model of the magnetic field, in which the controller (106) imports the primary digital signal, the model of the digitally predicted magnetic field, and digital compensation signal output.
    [0012]
    12. The method according to claim 11, characterized in that the transmission of digital signals occurs through direct electrical connections, an optical connection, an infrared connection, a wireless connection or a combination thereof.
    [0013]
    13. The method according to any one of claims 11 and 12, characterized in that after step E a storage medium (114) retains the primary digital signal, the digital compensation signal and the auxiliary sensor data.
    [0014]
    14. The method according to any one of claims 11 to 13, characterized in that the primary analog signal is created by detecting a superposition component of a primary magnetic field and a compensating magnetic field of a feedback coil. (503); wherein the method further comprises converting the secondary analog signal into a make-up current by a voltage-to-current converter (501); and sending the compensating current to the feedback coil (503) so as to create the compensating magnetic field which opposes the primary magnetic field and is emitted by the controller.
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    同族专利:
    公开号 | 公开日
    EP2976652A1|2016-01-27|
    US9389281B2|2016-07-12|
    AU2014234969A1|2015-10-01|
    EP2976652B1|2020-01-22|
    CN105393130A|2016-03-09|
    US20140288862A1|2014-09-25|
    AU2014234969B2|2017-07-06|
    BR112015023235A2|2017-06-06|
    RU2015144973A|2017-04-28|
    CA2907070A1|2014-09-25|
    RU2663682C2|2018-08-08|
    WO2014146184A1|2014-09-25|
    CL2015002822A1|2016-05-20|
    PE20151843A1|2015-12-11|
    CN105393130B|2019-03-15|
    DK2976652T3|2020-04-14|
    CA2907070C|2020-11-17|
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    法律状态:
    2018-11-13| B06F| Objections, documents and/or translations needed after an examination request according [chapter 6.6 patent gazette]|
    2020-02-11| B06U| Preliminary requirement: requests with searches performed by other patent offices: procedure suspended [chapter 6.21 patent gazette]|
    2021-10-05| B06A| Patent application procedure suspended [chapter 6.1 patent gazette]|
    2022-01-11| B09A| Decision: intention to grant [chapter 9.1 patent gazette]|
    2022-02-01| B16A| Patent or certificate of addition of invention granted [chapter 16.1 patent gazette]|Free format text: PRAZO DE VALIDADE: 20 (VINTE) ANOS CONTADOS A PARTIR DE 20/03/2014, OBSERVADAS AS CONDICOES LEGAIS. |
    优先权:
    申请号 | 申请日 | 专利标题
    US201361804097P| true| 2013-03-21|2013-03-21|
    US61/804,097|2013-03-21|
    PCT/BR2014/000093|WO2014146184A1|2013-03-21|2014-03-20|Magnetic compensation circuit and method for compensating the output of a magnetic sensor, responding to changes a first magnetic field|
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