JP2017194466A - Sensor self-diagnosis using multiple signal channels - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a system and method for use in sensor self-diagnosis using multiple signal channels.SOLUTION: According to an embodiment, a sensor is a magnetic sensor, and a system and/or method is constituted to meet a relevant safety standard such as an SIL standard or any other industrial standard, or to exceed these standards. For example, a monolithic integrated circuit sensor system mounted on a single semiconductor chip may have a first sensor device, which includes a first signal channel for a first sensor signal, included on the semiconductor chip, and may further have a second sensor device, which includes a second signal channel for a second sensor signal different from the first signal channel, included on the semiconductor chip. By comparing a signal on the first signal channel with a signal on the second signal channel, self-test of the sensor system is conducted.SELECTED DRAWING: Figure 1

Description

RELATED APPLICATION This application is a continuation-in-part (CIP) of US application Ser. No. 12 / 889,749 (US application Ser. No. 12 / 889,749) filed on Sep. 24, 2010. The entire disclosure is incorporated herein by reference.

TECHNICAL FIELD The present invention relates generally to integrated circuit (IC) sensors, and specifically to IC sensor self-diagnosis using multiple communication signal paths.

  As part of the development in the automotive electronics field, the recent trend in vehicle driving technology is the establishment of established passive safety systems such as seat belts and airbags, anti-lock braking systems (ABS), electronic stabilization (slip prevention) ) It is intended to be expanded by an active safety system such as a program (ESP) or an electric steering system to expand the range of driving support functions. As has been the case in drivetrains for some time now, systems are now becoming increasingly complex in order to detect dangerous driving situations and allow the control system to actively intervene to help prevent accidents. It is coming. As the technology continues to advance, this trend will continue as it is, and it is expected that it will become stronger in the future.

  As a result, the number of electronic components having safety-related functions has increased significantly, resulting in unprecedented requirements in terms of reliability and system availability. It would be desirable to develop an efficient method for functional self-monitoring with integrated test methods along with redundancy to be able to meet such requirements while meeting cost targets. ing. At the same time, it is also desirable to develop design techniques for the purpose of detecting and avoiding possible weaknesses in the safety system at an early stage. In the field of magnetic field sensors, for example, this has been done by the introduction of Safety Integrity Level (SIL) standards.

  In order to meet the SIL standard in the automotive field, not only at start-up but also during normal operation, implement and use corresponding self-tests, including built-in tests, and automatic monitoring structures or corresponding redundant functional blocks and / or Alternatively, it is required to provide a signal path. In conventional magnetic sensor systems, particularly linear Hall measurement systems, single channel analog main signal paths have been used. Meeting this SIL requirement in safety-critical applications with this concept is technically very difficult or perhaps even impossible to achieve. Thus, it is no longer possible to cover safety requirements with just one sensor system. Thus, two identical redundant magnetic field sensors have been used in other conventional solutions to meet SIL requirements. Needless to say, a significant disadvantage of these solutions is that the cost is doubled accordingly, since there are two sensors instead of one. Yet another solution has been proposed to superimpose a defined test signal outside the signal frequency range, for example by providing an additional on-chip conductor loop in the magnetic field sensor or superimposed on the sensor. Pressure sensors having electrostatic coupling.

  There remains a need for reliable and cost-effective sensor systems that meet SIL and / or other applicable safety standards.

  A more complete understanding of the present invention can be obtained when the following detailed description of the various embodiments of the invention is taken in conjunction with the accompanying drawings.

1 is a block diagram illustrating a system according to one embodiment. 1 is a block diagram illustrating a system according to one embodiment.

  While the present invention is applicable to various modifications and alternative forms, for the purpose of providing specific examples, the drawings illustrate specific embodiments thereof and are described in detail below. However, it will be appreciated that the invention is not intended to be limited to the specific embodiments described herein, but on the contrary, all modifications that fall within the spirit and scope of the invention as defined by the appended claims. Intended to encompass equivalent and alternative forms.

  Embodiments in accordance with the present invention relate to systems and methods for sensor self-diagnosis using multiple signal paths. According to one embodiment, the sensor is a magnetic field sensor, and the system and / or method is consistent with or superior to relevant safety standards such as SIL standards or other industry standards. It is comprised so that it may become.

  FIG. 1 shows a conceptual block diagram of a sensor system 100 according to one embodiment. System 100 includes a first sensor 102 and a second sensor 104, each of which communicates with a digital signal processor (DSP) 103. According to one embodiment, the first sensor 102, the second sensor 104, and the DSP 103 form a monolithic integrated circuit mounted on a single chip 105, and the DSP 103 is an external electronic control unit (ECU). ) 106.

  One of these sensors is a primary sensor or a main sensor. According to the embodiment of FIG. 1, the sensor 102 is a main sensor while the sensor 104 is a secondary sensor. The main sensor 102 communicates with the DSP 103 via a main signal path, and the secondary sensor 104 communicates with the DSP 103 via a secondary signal path that is at least partially different from the main signal path. This will be described in detail below.

  The secondary sensor 104 and the secondary signal path corresponding to this sensor are typically less accurate and slower than the main sensor 102 and / or noisy, operate using different modes of operation, and / or add Secondary sensing task. Thus, the secondary sensor 104 can be less costly than the main sensor 102, and the main sensor 102 is positioned for the positioning and chip area, as well as other factors that affect the cost and complexity of the system 100. There may be fewer constraints than the sensor 102. The secondary sensing tasks mentioned above are the measurement of compensation signals such as temperature, mechanical stress, internal operating voltage or bias voltage, operating current or bias current, and / or a simpler auxiliary measurement of the subject. For example, the sensors 102 and 104 include a magnetic field sensor according to one embodiment, in which case the measurement object of this type of sensor is a magnetic field. Nonetheless, in some embodiments, the secondary sensor 104 may include a plurality of sensors or sensor arrays, and by way of example, according to one embodiment, a magnetic field sensor that mirrors the main sensor 102 and a temperature sensor. And a stress sensor.

  However, according to one embodiment, the secondary sensor and the secondary signal path can be used for validity comparison with the main sensor and the main signal path. Further, the secondary sensor and secondary signal path can be used for fault detection and verification of the main sensor and main signal path. Such an arrangement can provide several advantages. First, SIL compatibility can be realized. Second, in contrast to conventional solutions, an advantage in size and cost can be realized, and self-tests can be performed during normal operation with little extra hardware. In addition, additional self-test functionality of digital signal processors (DSPs) and signal processing software can be implemented. In addition to these, the field failure rate and return rate can also be reduced, which improves cost effectiveness for both, ie for the original chip manufacturer and for the customer mounting the chip.

  Referring now to FIG. 2, an embodiment of a sensor system 200 based on the concept shown in FIG. 1 is depicted as a block diagram. System 200 includes a main magnetic field sensor 202 and a secondary magnetic field sensor 204, such as a Hall effect or a giant magnetoresistance (GMR). However, according to other embodiments, the sensors 202 and 204 may be other types of sensors, and these sensors are not limited to magnetic field sensors. The sensor 202 is similar in concept to the sensor 102, while the sensor 204 is similar in concept to the sensor 104, which have already been described with reference to FIG.

  The system 200 also includes one or more additional sensors 208, which are also considered secondary or auxiliary sensors. The one or more sensors 208 may include, in various embodiments, a temperature sensor, a stress sensor, a current sensor, a magnetic field sensor, or some other sensor type.

  According to one embodiment, the main sensor 202 communicates with a digital signal processing (DSP) unit 220. The DSP unit 220 itself can communicate with an external ECU or other control unit (see, for example, FIG. 1) via the input / output unit 210. According to one embodiment, the sensors 202 and 204 communicate with the DSP section 220 via separate signal paths, which can include structurally different analog signal paths, combined signal paths. Further, for a specific range, digital signal paths and digital signal processing units, and software components can be included. In FIG. 2, the main signal path associated with the main sensor 202 is indicated by a bold line, while the secondary signal path associated with the sensor 204 is indicated by a simple broken line.

  For example, according to the embodiment of FIG. 2, the main signal path can carry signals from the main sensor 202 to the analog / digital (A / D) converter 212 and the cross switch 214 of the A / D conversion channel. The secondary signal path communicates signals from the secondary sensor 204 to the multiplexer 216, which receives as an input all signals from the additional sensor or auxiliary sensor 208 as well. The secondary signal path then continues from the MUX 216 to the second A / D converter 218, which also sends its output to the cross switch 214.

  According to one embodiment, the elements of the main signal path and the elements of the secondary signal path are not identical and / or are implemented using different modes of operation. For example, the A / D converter 212 in the main signal path can have a third order delta sigma converter, while the A / D converter 218 in the secondary signal path has a first order delta sigma converter. Or one or more A / D converters can use successive approximation register (SAR) type or flash type technology rather than delta sigma type. In other words, the secondary sensor 204 is typically less accurate and slower than the main sensor 102 and / or noisy, operates using different modes of operation, and / or additional secondary sensing tasks. Similarly, the same applies to the A / D converter 218 when compared to the A / D converter 212. Further, when the secondary sensor 204 is compared with the main sensor 102, the sampling rate is low, the latency time is large, the bandwidth is small, the analog / digital conversion resolution is low, and the signal range can be narrowed. Further, the signal encoding may be different, the sensor signal mapping may be different, the compensation algorithm may be different, and / or the processing schedule may be different. Moreover, the secondary sensor 204 can include fewer second sensing elements than the main sensor 102 including the first sensing element. Further, the secondary sensor 204 may include a second sensing element having a second detection area that is narrower than the main sensor 102 including the first sensing element having the first detection area.

  Different modes of operation can be implemented in any of several ways. Different operating schemes can be realized as hardware implementation for the functional part with the first signal path, while the corresponding functional part of the second signal path is realized in software. As another option, different modes of operation can be realized using different sensing techniques for the first signal path than for the second signal path. As yet another option, a different mode of operation is at least partly different from the second functional part of the second signal path corresponding to the first functional part with respect to the first functional part of the first signal path. It can be implemented by adopting different functional processing hardware.

  The output of the cross switch 214 is associated with both the main signal path and the secondary signal path, and is supplied to the digital signal processing (DSP) unit 220. According to one embodiment, the DSP 220 includes a state machine 222, a clamping algorithm 224, and a memory matrix 226. In conformity with the concept of providing a main signal path and a secondary signal path, the DSP 220 also includes a first software section associated with the main signal path and a second software section associated with the secondary signal path. It is. In addition or alternatively, the DSP 220 may implement different DSP or DSP techniques for the main signal path and the second signal path, respectively. According to one embodiment, the DSP 220 is connected to the I / O 210 via the interface 228, and the I / O 210 itself is connected to an external ECU (not shown in FIG. 2). .

  The DSP 220 can be implemented as a multi-core processor or as two or more DSPs. In this case, the multi-core DSPs may have the same core or different cores. Further, the DSP 220 may have a provider's DSP in the main path and a provider's multi-core DSP in the secondary signal path.

  In this way, the main signal path and the secondary signal path can provide two different so-called redundant analog signal paths, and these signal paths provide a number of useful characteristics. For example, transmitting the main magnetic field signal from the sensor 202 in one cycle via the main signal path can provide a highly accurate calculation result. Here, the main signal path itself operates rapidly with at least much higher accuracy than the secondary signal path, such as by using chopping or other techniques. Furthermore, the main signal path is free to operate independently without being affected by other system components.

  An option is also provided to supply its data to the control unit via a secondary signal path for analysis purposes, where the data can be processed with either a positive or negative polarity code. While the system 200 has been shown to allow parallel output from the DSP 220 to the interface 228 and I / O 210, it is also possible to implement sequential transmission, for example using time division multiplexing or on demand as an external request. it can.

  The output from the DSP 220 to the interface 228 can be sent out through only one terminal. From this terminal, in some cases, the first output signal associated with the main signal path will be supplied according to the multiplex method, and in other cases, according to the multiplex method, A second output signal associated with the signal path will be provided.

  The sensors 202 and 204, and optionally the sensor 208, can use different sensing schemes for their measurements, such as processing techniques, technical performance and specifications, sensors 202 and 204. Includes its size and / or placement, and biasing. One embodiment of the system 200 includes two bandgap biasing units 230 and 232 and a biasing comparison unit 234. The biasing unit 230 is associated with the main signal path, and the biasing unit 232 is associated with the secondary signal path. The biasing units 230 and 232 provide different biasing options for the sensors 102 and 104, while the biasing comparison unit 234 allows the output signal to the DSP 220 to be considered.

  Further, according to some embodiments of the system 200, different A / D conversion and / or switching concepts may be used via the A / D converters 212 and 218 and the cross switch 214, respectively. For example, as described above, the A / D converter 212 in the main signal path may have a third-order delta-sigma converter, while the A / D converter 218 in the secondary signal path has 1 Can have the following delta-sigma type converters, or one or more A / D converters use successive approximation register (SAR) type or flash type techniques rather than delta-sigma type it can. In various embodiments, such different A / D conversion and / or switching concepts can result in different failure behavior and / or probability of failure. Further, in some embodiments, the measurement range can be switched via the previously described inputs to the A / D converters 212 and 218 of FIG. 2 for the purpose of detecting clamping or limiting effects.

  Further, according to some embodiments, an option may be provided to switch between the sensors 202 and 204 and their respective main and secondary signal paths. For example, the secondary sensor 204 can be switched to the main signal path, and the same applies to the sensor 202 and the secondary signal path. This option can improve fault detection and / or fault location, for example by making the sensor independent of its path.

  Another advantage provided by the embodiment of the system 200 is that the output signal of each of the main signal path and the secondary signal path can be compared and the result can be evaluated, such as by forming a quotient. This result can be evaluated to determine one or more situations related to the performance or function of sensors 202 and 204, each signal path, system 200, and / or some other component. For example, a rapid change in the input signal can be detected by comparing the output signals. In embodiments that use compensation, such as temperature compensation, if the sensor 208 includes a temperature sensor, the output signal can be compared depending on the temperature compensation signal. According to yet another embodiment, clamping or limiting of information from sensor 208 can be implemented to separate other signals, characteristics, or information.

  Since DSP 220 uses software 1 for the main signal path and software 2 for the secondary signal path, according to some embodiments, the output results of these signal paths can be compared. Such a comparison makes it possible to check the software algorithm itself. Internal or external window comparisons can be used in the validity checking of the two signal paths or comparison results of the DSP 220. As part of this type of validity check, warning and / or failure thresholds can be implemented.

  The comparison of the output results of the two signal paths includes the quotient of each output result of the two signal paths, the linear transformation, and the comparison between the absolute value of the difference between the output results of the two signal paths and the difference threshold value. At least one of them can be included.

  Thus, according to some embodiments, safety standard compatibility as well as fault self-diagnosis in sensor systems can be provided. Depending on the type and rigor and the particular system of interest and / or related standards, the handling of faults may vary, but according to some embodiments, the detected problem is communicated to the system user. It will be possible to provide an opportunity to warn. For example, in safety critical automotive electronic power steering sensor applications that use magnetic field sensors, critical system issues can be communicated to the ECU so that appropriate actions can be taken. Can be alerted to the driver. In some applications, the ECU can be programmed to switch to safe mode or safe operating protocol in the event of an error, failure or deviation.

  Further, some embodiments are more efficient in space and cost than conventional solutions using redundant primary sensors. For example, according to some embodiments, only one primary sensor is used instead of two primary sensors, and the secondary sensor is a device that is generally less costly in terms of reduced performance requirements. For example, the chip area can be suppressed to less than 10% by the main / secondary sensor and the signal path. An advantage over conventional solutions using two primary sensors on a single chip is also achieved in that the cost of the secondary sensor is reduced.

  Various embodiments relating to systems, devices and methods have been described above. These embodiments are merely presented for the purpose of illustrating specific examples and are not intended to limit the scope of the present invention. In addition, it should be understood that various features of the embodiments described above can be combined in various ways to create a number of additional embodiments. Also, although various materials, dimensions, shapes, installation locations, etc. have been described for use with the disclosed embodiments, others other than those disclosed herein may be used without exceeding the scope of the invention. be able to.

  Furthermore, as will be apparent to those skilled in the art, the features that can be included in the present invention may be fewer than those shown in any of the individual embodiments described above. Further, the embodiments described here are not intended to present all the techniques that can combine various features of the present invention. Thus, these embodiments are not mutually exclusive features, but rather, the present invention will be understood by those skilled in the art of various individual features selected from the various individual embodiments. Combinations can be included.

  Any incorporation by reference of documents cited above is limited so that it does not incorporate gist contrary to the explicit disclosure of this application. Further, any incorporation by reference of the above-mentioned documents is further limited so that the claims included in the documents are not incorporated by reference. Moreover, any incorporation by reference of documents cited above is further restricted so that any definition presented in the document is not incorporated by reference unless otherwise stated herein.

  For the purpose of interpreting the claims of the present invention, it is specifically intended that the provisions of 35 USC 35 USC 112 (6) include the specific terms "means for" or “Step for” does not apply unless stated in the claims.

Claims (38)

A monolithic integrated circuit,
A first sensor device configured to indicate a physical quantity and having a first signal path for a first sensor signal on a semiconductor chip;
A second sensor device configured to indicate the physical quantity and having a second signal path for a second sensor signal on the semiconductor chip;
Is provided,
The second signal path is separate and different from the first signal path, and compared to the first signal path than the first signal path,
Low sampling rate, long latency time, narrow bandwidth, low accuracy, large noise, low analog to digital conversion resolution, and narrow signal range,
Having at least one characteristic selected from the group consisting of:
The second sensor device includes fewer second sensing elements than the first sensor device including a first sensing element;
The second sensor device includes a second sensing element having a second sensing area that is narrower than the first sensor device including a first sensing element having a first sensing area, and has a different operation method. Have different signal encodings, different sensor signal mappings, different compensation algorithms, and different processing schedules,
A first output signal associated with the first signal path and a second output signal associated with the second signal path can be transmitted from the monolithic integrated circuit to an external control unit;
Monolithic integrated circuit. The different operating scheme is realized as a hardware implementation for the functional part of the first signal path, while the corresponding functional part of the second signal path is realized as software,
The monolithic integrated circuit according to claim 1. The different modes of operation are realized using a different sensing technique for the first signal path than for the second signal path,
The monolithic integrated circuit according to claim 1. The different mode of operation is at least partially different from the second functional part of the second signal path corresponding to the first functional part because of the first functional part of the first signal path. Realized by adopting functional processing hardware,
The monolithic integrated circuit according to claim 1. A digital signal processor (DSP) connected to the first signal path and the second signal path is received on the semiconductor chip to receive the signals of the first signal path and the second signal path. And the DSP is configured to compare the signal of the first signal path and the signal of the second signal path.
The monolithic integrated circuit according to claim 1. The DSP includes a first digital signal processor associated with the first signal path and a second digital signal processor associated with the second signal path.
The monolithic integrated circuit according to claim 2. The DSP is connected to the first signal path and the second signal path by a cross-switching device of an analog / digital (A / D) conversion channel.
The monolithic integrated circuit according to claim 2. There is further provided at least one additional sensor device connected to one of the first signal path and the second signal path;
The monolithic integrated circuit according to claim 1. The at least one additional sensor device is selected from the group consisting of a temperature sensor, a stress sensor, a current sensor, a voltage sensor, and a magnetic field sensor.
The monolithic integrated circuit according to claim 8. A multiplexer is further provided on the semiconductor chip, the multiplexer including the second sensor device and the at least one additional sensor device out of the first signal path and the second signal path. Configured to connect to one selected route,
The monolithic integrated circuit according to claim 8. The first sensor device and the second sensor device include a magnetic field sensor,
The monolithic integrated circuit according to claim 1. A first biasing circuit connected to the first sensor device and the first signal path; and a second biasing circuit connected to the second sensor device and the second signal path. Provided,
The monolithic integrated circuit according to claim 1. A biasing comparator is further provided, wherein the biasing comparator receives a first biasing signal from the first biasing circuit, receives a second biasing signal from the second biasing circuit, and Configured to compare one biasing signal with the second biasing signal;
The monolithic integrated circuit according to claim 12. A method for monitoring a monolithic integrated circuit, comprising:
Mounting a main signal path having a main sensor on a single semiconductor chip;
Mounting a secondary sensor and a secondary signal path on the single semiconductor chip;
However, the secondary signal path is separated from the main signal path and is different from the main signal path. Compared with the main signal path, the secondary signal path has a lower sampling rate, longer latency time, narrow bandwidth, and lower accuracy than the main signal path. Having at least one characteristic selected from the group consisting of: high noise, low analog / digital conversion resolution, narrow signal range, and different modes of operation;
The secondary sensor includes a second sensing element that is smaller than the main sensor including the first sensing element, and the secondary sensor is narrower than the main sensor including the first sensing element of the first detection area. Comprising a second sensing element of a second sensing area and having a different mode of operation, a different signal encoding, a different sensor signal mapping, a different compensation algorithm, and a different processing schedule,
Supplying a signal of the main signal path as a first output signal and supplying a signal of the secondary signal path as a second output signal;
Comparing the first output signal and the second output signal;
Including methods. Further comprising multiplexing at least one additional sensor into the secondary signal path;
The method of claim 14. Receiving at least one compensation signal from the at least one additional sensor;
The method of claim 15. Biasing the main sensor with a first biasing unit;
Biasing the secondary sensor with a second biasing unit different from the first biasing unit;
Measuring the bias current of the main sensor and the bias current of the secondary sensor;
Further including
The method of claim 14. Connecting the main signal path and the secondary signal path to a digital signal processor (DSP);
Processing the signal of the main signal path using a first software portion of the DSP to determine the first output signal;
Using the second software portion of the DSP different from the first software portion to process the signal of the secondary signal path and determining the second output signal;
Further including
The method of claim 14. Further comprising providing a parallel output section of the DSP, including a main signal path section and a secondary signal path section.
The method of claim 18. The step of comparing includes forming at least one of a quotient or linear transformation of the signal of the main signal path and the signal of the secondary signal path,
The method of claim 14. Further comprising evaluating at least one of the quotient or the linear transformation;
The method of claim 20. The method further includes the step of adjusting the measurement range of the selected sensor of the main sensor or the secondary sensor while maintaining the measurement range of the unselected sensor of the main sensor or the secondary sensor unchanged. ,
The method of claim 14. Further comprising replacing the main sensor and the secondary sensor such that the main sensor is connected to the secondary signal path and the secondary sensor is connected to the main signal path.
The method of claim 14. The external control unit is
Providing a warning in response to the communicable first and second output signals received and compared by the external control unit;
Configured as
The monolithic integrated circuit according to claim 2. Providing the first output signal by the main signal path;
Supplying the second output signal by the secondary signal path unit;
Further including
The method of claim 19. Supplying the first output signal by one output unit;
Supplying the second output signal by the output unit using time division multiplexing;
Further including
The method of claim 18. Further comprising connecting the parallel output of the DSP to an external control unit;
26. The method of claim 25. Providing a warning by the external control unit as a result of the comparing step;
27. The method of claim 26. Performing the comparing step on the single semiconductor chip;
The method of claim 14. As a result of the comparing step,
Identification of errors or deviations of the monolithic integrated circuit,
A validity check of at least one of the sensor, the signal path, or the DSP, or
At least one verification of the sensor, the signal path, or the DSP;
Providing at least one of
The method of claim 14. The first output signal and the second output signal can be transmitted from the monolithic integrated circuit to the external control unit for comparison.
The monolithic integrated circuit according to claim 1. For the comparison,
Identification of errors or deviations of the monolithic integrated circuit;
A validity check of at least one of the sensor, the signal path or the DSP;
Verification of at least one of the sensor, the signal path or the DSP;
At least one of
32. A monolithic integrated circuit according to claim 31. The comparison includes a quotient of the first output signal and the second output signal, linear transformation, and a comparison between a difference absolute value and a difference threshold value between the first output signal and the second output signal. Of which at least one formation is included,
32. A monolithic integrated circuit according to claim 31. Implementing a first analog / digital (A / D) conversion technique in the main signal path;
Implementing a second A / D conversion technique different from the first A / D conversion technique in the secondary signal path;
Further including
The method of claim 14. The first signal path includes a first analog / digital (A / D) converter, and the second signal path is a second A / D different from the first A / D converter. Including a converter,
The first output signal associated with the first signal path from the first A / D converter and the second signal path associated with the second signal path from the second A / D converter. 2 output signals can be transmitted from the monolithic integrated circuit to the external control unit;
The monolithic integrated circuit according to claim 1. The first A / D converter operates by at least one operation method different from the operation method of the second A / D converter.
36. A monolithic integrated circuit according to claim 35. The DSP includes a first digital signal processing unit associated only with the first signal path and a second digital signal processing unit associated only with the second signal path.
The monolithic integrated circuit according to claim 2. The external control unit is configured to receive and compare the transmittable first output signal and the second output signal.
The monolithic integrated circuit according to claim 2.

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