Sensor Device

Abstract

To provide a sensor device capable of appropriately retaining power supply missing information.SOLUTION: A rotation angle sensor 30 of a sensor device 1 includes detection elements 31 to 33, a sensor information calculation unit, a power supply missing determination circuit 355, and a communication unit 359, and can continue at least part of operation by being supplied with power from a battery power feeding line Lb even while a start switch 901 is turned off. A control unit 60 includes a communication unit 69, a control calculation unit 65, and a nonvolatile memory 67, and operates with power supplied via the start switch 901. After the starting switch 901 is turned on, the control unit 60 acquires, from the rotation angle sensor 30, power supply missing information regarding a power supply missing while the starting switch 901 was turned off, and transmits a recovery signal to the rotation angle sensor 30 after storing the power supply missing information in the nonvolatile memory 67.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a sensor device. [Background technology]

[0002] Conventionally, there are known rotation angle detection devices that detect the rotation angle of a motor, etc. For example, the rotation angle detection device disclosed in Patent Document 1 is applied to an electric power steering device, and can continue at least a part of its operation using power from a battery while the ignition power supply is turned off. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-161584 Summary of the Invention [Problem to be solved by the invention]

[0004] The rotation angle detection device of Patent Document 1 transmits a power failure determination result to a control unit, and when the control unit receives a recovery signal transmitted from the control unit after receiving the power failure determination result, the power failure flag is reset. Here, if the control unit is reset after transmitting the recovery signal from the control unit to the rotation angle detection device, the power failure information is lost.

[0005] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a sensor device that can appropriately retain power supply failure information. [Means for solving the problem]

[0006] The sensor device of the present invention includes a sensor unit (30) and a control unit (60). The sensor unit has detection elements (31-33), a power supply failure determination circuit (355), and a sensor-side communication unit (359), and can continue at least a part of its operation by receiving power from a battery power line (Lb) even while the starter switch is turned off.

[0007] The detection element detects a change in a physical quantity corresponding to the movement of the detection target 80. The power supply failure determination circuit can determine a power supply failure in which power is not supplied from the battery power line without passing through the start switch 901. The sensor-side communication unit transmits sensor information including power supply failure information indicating whether a power supply failure has occurred.

[0008] The control unit has a control unit communication unit (69), a control calculation unit (65), and a nonvolatile memory (67), and operates on power supplied via the start switch. The control unit communication unit receives sensor information from the sensor unit and transmits a recovery signal to the sensor unit to instruct it to reset the power failure information. The control calculation unit performs control calculations using the sensor information. The nonvolatile memory stores the power failure information.

[0009] The control unit acquires power failure information from the sensor unit while the start switch is off, stores the power failure information in a nonvolatile memory, and then transmits a recovery signal to the sensor unit, thereby enabling the power failure information to be properly maintained. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic configuration diagram of a steering system according to a first embodiment. [Figure 2] 1 is a block diagram showing a sensor device according to a first embodiment; [Figure 3] 5 is a flowchart illustrating a power failure information transmission process according to the first embodiment. [Figure 4] 5 is a flowchart illustrating a power failure information holding process according to the first embodiment. [Figure 5]FIG. 10 is an explanatory diagram illustrating virtual sectors of a nonvolatile memory in a second embodiment. [Figure 6] 10 is a flowchart illustrating a power failure information holding process according to the second embodiment. [Figure 7] FIG. 11 is an explanatory diagram illustrating a data area of ​​a virtual sector according to the third embodiment. [Figure 8] 10 is a flowchart illustrating a power failure information holding process according to the third embodiment. [Figure 9] 10 is a flowchart illustrating a data read process according to the third embodiment. [Figure 10] 10 is a flowchart illustrating a power failure information holding process according to the fourth embodiment. [Figure 11] 13 is a flowchart illustrating a power failure information holding process according to the fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A rotation detection device according to the present invention will be described below with reference to the accompanying drawings. In the following, substantially identical components in a plurality of embodiments will be designated by the same reference numerals, and the description thereof will be omitted.

[0012] (First embodiment) A first embodiment is shown in Figures 1 to 4. As shown in Figures 1 and 2, a sensor device 1 is applied to an electric power steering device 8. Figure 1 shows the configuration of a steering system 90 equipped with the electric power steering device 8. The steering system 90 includes a steering wheel 91, which is a steering member, a steering shaft 92, a pinion gear 96, a rack shaft 97, wheels 98, the electric power steering device 8, and the like.

[0013] The steering wheel 91 is connected to a steering shaft 92. A torque sensor 94 that detects steering torque is provided on the steering shaft 92. A pinion gear 96 is provided at the tip of the steering shaft 92. The pinion gear 96 meshes with a rack shaft 97. A pair of wheels 98 are connected to both ends of the rack shaft 97 via tie rods or the like.

[0014] When the driver turns the steering wheel 91, the steering shaft 92 connected to the steering wheel 91 rotates. The rotational motion of the steering shaft 92 is converted into linear motion of a rack shaft 97 by a pinion gear 96. A pair of wheels 98 is steered to an angle corresponding to the amount of displacement of the rack shaft 97.

[0015] The electric power steering device 8 includes a drive unit 10 having an ECU 20 and a motor 80, and a reduction gear 89, which is a power transmission unit that reduces the rotation of the motor 80 and transmits it to a steering shaft 92. That is, the electric power steering device 8 of this embodiment is a so-called "column assist type," and the steering shaft 92 can be said to be the driven object. It may also be a so-called "rack assist type," in which the rotation of the motor 80 is transmitted to a rack shaft 97.

[0016] The motor 80 outputs part or all of the torque required for steering, and is driven by power supplied from a battery 900 (see FIG. 2 ), causing a reduction gear 89 to rotate forward and reverse. The drive device 10 is a so-called "mechatronically integrated" type in which the ECU 20 is provided on one axial side of the motor 80, but may also be a mechatronically separate type in which the motor and the ECU are provided separately. The mechatronically integrated type allows the ECU 20 and the motor 80 to be efficiently arranged in a vehicle with limited installation space. The ECU 20 is provided with a sensor device 1.

[0017] As shown in FIG. 2, the sensor device 1 is a rotation detection device that detects the rotation of a motor 80 and includes a rotation angle sensor 30 and a control unit 60. The rotation angle sensor 30 has detection elements 31 to 33 and a signal processing unit 35. The detection elements 31, 32, and 33 are provided on sensor chips 310, 320, and 330, respectively, and the signal processing unit 35 is provided on a signal processing chip 350. Alternatively, multiple detection elements may be provided on a single chip and separated by insulating units. The sensor chips 310, 320, and 330 and the signal processing chip 350 are sealed in a sealing unit 38.

[0018] The detection elements 31 to 33 are, for example, magnetic resistance elements such as AMR sensors, TMR sensors, and GMR sensors, or Hall elements, and detect the magnetic field of a sensor magnet (not shown) that rotates integrally with the shaft of the motor 80, and output a pair of sine and cosine signals, which are analog signals. The detection elements 31 to 33 may be the same, or may have different amplitudes, etc. Furthermore, the detection elements 31 may have different performance, for example, the detection element 31 may have higher detection accuracy than the detection elements 32 and 33. If at least some of the detection elements 31 to 33 are of different types, the failure modes are different, and the probability of simultaneous failures occurring can be reduced.

[0019] The signal processing unit 35 has an AD conversion unit 351, an angle calculation unit 352, a rotation count calculation unit 353, a power supply failure determination circuit 355, and a communication unit 359. The AD conversion unit 351 converts the sine signal and cosine signal output from the detection element 31 into digital signals.

[0020] Angle calculation unit 352 calculates motor rotation angle θm1 using the digitally converted detection value of detection element 31. Rotation count calculation unit 353 calculates the number of rotations TC of motor 80 using the digitally converted detection value of detection element 31 by AD conversion unit 351. The number of rotations TC can be calculated based on the count value, for example, by dividing one rotation of motor 80 into three or more regions and counting up or down depending on the direction of rotation each time the region changes.

[0021] The power failure determination circuit 355 has a volatile memory 356 and determines a power failure in which the direct power supply from the battery 900 via the power terminal 385 is interrupted. The volatile memory 356 functions as a power failure flag. That is, if the normal value is "1," it is assumed that no power failure has occurred and the power failure flag is not set. On the other hand, if a power failure occurs, the volatile memory 356 is reset to the initial value "0," and the power failure flag is assumed to be set.

[0022] The communication unit 359 is configured with a serial interface and transmits a digital signal including information related to the motor rotation angle θm1 and the number of rotations TC to the control unit 60. The motor rotation angle θm1 and the number of rotations TC are used by the control unit 60 for various control calculations. The communication unit 359 also transmits the power failure determination result to the control unit 60. Specifically, if the volatile memory 356 has an initial value of "0," the communication unit 359 transmits "0" as the bit information corresponding to the power failure determination result. If the volatile memory 356 has a normal value of "1," the communication unit 359 transmits "1" as the bit information corresponding to the power failure determination result. In this embodiment, to prevent bit corruption, a two-bit area is used as the power failure determination result to prevent erroneous determination. The control unit 60 considers the power failure flag to be set if both of the two bits are "0."

[0023] The communication unit 359 also receives a recovery signal from the control unit 60. The recovery signal is a signal that commands the volatile memory 356 to recover from the initial value "0" to the normal value "1," and can also be considered as a signal to reset the power failure flag. That is, the rotation angle sensor 30 holds the power failure information until it receives a recovery signal from the control unit 60, and when it receives the recovery signal, the power failure information is reset.

[0024] The sealing portion 38 is provided with output terminals 381 to 383 and power supply terminals 385 to 388. The output terminal 381 is connected to a terminal 601 of the control unit 60 and is used to output a digital signal including a value calculated using the detection value of the detection element 31. The output terminal 382 is connected to a terminal 602 of the control unit 60 and is used to output an analog signal corresponding to the detection value of the detection element 32. The output terminal 383 is connected to a terminal 603 of the control unit 60 and is used to output an analog signal corresponding to the detection value of the detection element 33. In other words, the rotation angle sensor 30 of this embodiment has a "mixed digital-analog" configuration.

[0025] 2, one output terminal 381-383 and one communication line are provided for each system, but multiple terminals may be provided for at least some systems depending on the communication method and data method. Amplification circuits, filter circuits, etc. may also be provided as appropriate. Furthermore, by providing NC (Non Connection) terminals between terminals 601-603, it is possible to prevent multiple signals from becoming abnormal due to a common cause failure such as a short circuit between adjacent terminals caused by a foreign object, etc.

[0026] The power supply terminal 385 is connected to the battery 900. The battery power supply line Lb connects the battery 900 and the power supply terminal 385 without passing through a start switch 901 (hereinafter referred to as "IG" as appropriate in the drawings, etc.), which is an ignition switch or the like of the vehicle. The power supply terminals 386 to 388 are connected to the battery 900 via the start switch 901. The power supply terminals 385 to 388 may be supplied with power whose voltage has been increased or decreased from the battery 900 or the start switch 901.

[0027] Power supply terminals 385 and 386 are connected to the sensor chip 310 and the signal processing chip 350. The detection element 31, AD conversion unit 351, rotation count calculation unit 353, and power supply failure determination circuit 355, all of which are enclosed by a dashed dotted line, are constantly powered even while the IG is off via the power supply terminal 385. This allows the rotation count TC to continue to be calculated even while the IG is off.

[0028] Furthermore, while the IG is off, no power is supplied to the angle calculation unit 352 and the communication unit 359, and processing is stopped. Power supply terminal 387 is connected to the sensor chip 320, and power supply terminal 388 is connected to the sensor chip 330. That is, in this embodiment, power supply terminals 385 to 388 are individually provided for each of the detection elements 31 to 33, and the power supplies are configured to not interfere with each other. The detection elements 31 to 33 are also configured to ensure insulation between the elements.

[0029] The control unit 60 is mainly composed of a microcomputer or the like, and includes a CPU, ROM, RAM, I / O, and bus lines connecting these components (all not shown). Each process in the control unit 60 may be software processing in which the CPU executes a program stored in advance in a physical memory device (i.e., a readable non-transitory tangible storage medium) such as a ROM, or may be hardware processing using a dedicated electronic circuit.

[0030] The control unit 60 includes AD conversion units 62 and 63, an angle calculation unit 64, a control calculation unit 65, a power failure information holding circuit 66, and a communication unit 69. The AD conversion units 62 and 63 convert the analog signals output from the detection elements 32 and 33 into digital signals. In this embodiment, the AD conversion units 62 and 63 are provided on the control unit 60 side, and the detection signals from the detection elements 32 and 33 are not converted to digital signals but are output as analog signals to the control unit 60. In other words, the rotation angle sensor 30 does not include any components related to signal processing of the detection elements 32 and 33, simplifying the configuration of the rotation angle sensor 30.

[0031] Angle calculation unit 64 calculates motor rotation angles θm2, θm3 based on the signal from rotation angle sensor 30. In detail, angle calculation unit 64 calculates motor rotation angle θm2 using the digitally converted detection value of detection element 32, and calculates motor rotation angle θm3 using the digitally converted detection value of detection element 33. Hereinafter, when it is not necessary to distinguish between detection elements 31 to 33, it will simply be referred to as motor rotation angle θm.

[0032] Furthermore, the angle calculation unit 64 calculates the absolute angle θa, which is the amount of rotation from a reference position including multiple rotation information, based on the motor rotation angle θm and the number of rotations TC. The absolute angle θa is a value that can be converted to a steering angle θs using a gear ratio or the like. In this embodiment, the angle calculation unit 64 performs an abnormality determination by comparing the motor rotation angles θm1 to θm3 based on signals from the three detection elements 31 to 33, and calculates the absolute angle using the normal value.

[0033] In the first calculation, the angle calculation unit 64 calculates the absolute angle θa using the motor rotation angle θm and the number of rotations TC, and in the second and subsequent calculations, the absolute angle θa is calculated by integrating the difference of the motor rotation angle θm. Note that the absolute angle θa may be calculated using the number of rotations TC each time, or calculations using the number of rotations TC may be performed at a predetermined frequency to detect software abnormalities, correct errors, etc.

[0034] In this embodiment, calculation of the number of rotations TC continues even while the IG is off. As a result, even if the motor 80 rotates as a result of the steering wheel 91 being steered while the IG is off, the steering angle θs can be calculated without relearning the reference position. Note that, since the value when the IG is on can be used for the motor rotation angle θm, it is not necessary to continue calculation with constant power supply.

[0035] The control calculation unit 65 performs various calculations related to the drive control of the motor 80. The power failure information holding circuit 66 has a nonvolatile memory 67. The nonvolatile memory 67 stores power failure information, which is information regarding whether or not a power failure has occurred in the rotation angle sensor 30. The communication unit 69 receives sensor information including the power failure information from the rotation angle sensor 30, and transmits recovery information to the rotation angle sensor 30. Note that some control lines have been omitted in FIG. 2 to avoid complexity.

[0036] When the IG is off, the control unit 60 is not supplied with power and stops processing. When the IG is turned on, the control unit 60 acquires power failure information from the rotation angle sensor 30, and after acquiring the power failure information, transmits a recovery signal to the rotation angle sensor 30, thereby being able to reset the power failure information of the rotation angle sensor 30.

[0037] For example, if the battery is nearing the end of its life, a large current flowing through the starter when the engine is started may cause a drop in battery voltage, which may disable the control unit 60 and cause it to be reset. If the control unit 60 is reset after transmitting a recovery signal, there is a risk that the power failure history will not be retained on either the rotation angle sensor 30 side or the control unit 60 side. Therefore, in this embodiment, before transmitting the recovery signal, power failure information is stored in the non-volatile memory 67. Furthermore, if a power failure has occurred, the control unit 60 notifies other devices (such as a higher-level ECU) of this information.

[0038] The power failure information transmission process of this embodiment will be described with reference to the flowcharts of Fig. 3 and Fig. 4, respectively. The power failure information storage process shown in Fig. 3 is executed at a predetermined cycle by the signal processing unit 35 of the rotation angle sensor 30. Hereinafter, the "step" in step S101 and other steps will be omitted and simply referred to as "S".

[0039] In S101, the signal processing unit 35 determines whether or not it has received a request signal transmitted from the control unit 60. If it is determined that it has not received a request signal (S101: NO), it proceeds to S103. If it is determined that it has received a request signal (S101: YES), it proceeds to S102, and transmits power failure information to the control unit 60.

[0040] In S103, the signal processing unit 35 determines whether or not a return signal transmitted from the control unit 60 has been acquired. If it is determined that a return signal has not been acquired (S103: NO), the processing of S104 is skipped. If it is determined that a return signal has been acquired (S103: YES), the processing proceeds to S104, where return processing is performed. Specifically, the volatile memory 356 is returned to the normal value "1".

[0041] 4 is executed by the control unit 60 when the IG is turned on. In S201, the control unit 60 transmits a request signal to the rotation angle sensor 30 requesting power failure information.

[0042] In S202, the control unit 60 determines whether or not power failure information has been acquired from the rotation angle sensor 30. If it is determined that power failure information has not been acquired (S202: NO), this determination process is repeated. If it is determined that power failure information has been acquired (S202: YES), the process proceeds to S203.

[0043] In S203, the control unit 60 determines whether there is free space in the nonvolatile memory 67. If it is determined that there is no free space (S203: NO), the process proceeds to S204, where data is erased from the write area of ​​the nonvolatile memory 67. If it is determined that there is free space (S203: YES), S204 is skipped and the process proceeds to S205.

[0044] In S205, the control unit 60 stores the power failure information acquired from the rotation angle sensor 30 in the nonvolatile memory 67. In S206, the control unit 60 transmits a recovery signal to the rotation angle sensor 30.

[0045] In S207, the control unit 60 determines whether or not there was a power failure to the rotation angle sensor 30 while the ignition was off. If it is determined that there was no power failure while the ignition was off (S207: NO), the process of S208 is skipped. If it is determined that there was a power failure while the ignition was off (S207: YES), the process proceeds to S208.

[0046] In S208, the control unit 60 acquires alternative information from the external device 500 that allows calculation of the number of rotations TC, and performs control using the alternative information. In this embodiment, the external device 500 is, for example, a steering sensor, and acquires steering angle information based on a detection value from the steering sensor or the like as the alternative information. The angle calculation unit 64 calculates the absolute angle θa using the alternative information. In addition, a correction process is performed to adjust the reference value when the vehicle is traveling straight, and the correction information is stored in the non-volatile memory 67 as information related to the alternative information control.

[0047] In this embodiment, when the IG is turned on, the control unit 60 stores the power failure information acquired from the rotation angle sensor 30 in the nonvolatile memory 67 and then transmits a recovery signal to the rotation angle sensor 30. As a result, even if the control unit 60 is reset due to a drop in battery voltage caused by cranking, for example, the power failure history is retained in the rotation angle sensor 30 or the nonvolatile memory 67.

[0048] As described above, the sensor device 1 includes the rotation angle sensor 30 and the control unit 60. The rotation angle sensor 30 has detection elements 31 to 33, a power supply failure determination circuit 355, and a communication unit 359, and can continue at least a part of its operation by receiving power from the battery power supply line Lb even while the start switch 901 is turned off.

[0049] The detection elements 31 to 33 detect changes in physical quantities corresponding to the operation of the motor 80, which is the detection target. The power supply failure determination circuit 355 can determine a power supply failure in which power is no longer supplied from the battery power supply line Lb without passing through the start switch 901. The communication unit 359 transmits sensor information including power supply failure information relating to whether a power supply failure has occurred. In addition to the power supply failure information, the sensor information includes rotation angle information, rotation count information, and abnormality information of the rotation angle sensor 30.

[0050] The control unit 60 has a communication unit 69, a control calculation unit 65, and a nonvolatile memory 67, and operates on power supplied via a start switch 901. In other words, the control unit 60 stops operating while the start switch 901 is turned off. Note that the information stored in the nonvolatile memory 67 is retained even when the start switch 901 is turned off.

[0051] The communication unit 69 receives sensor information from the rotation angle sensor 30 and transmits a recovery signal to the rotation angle sensor 30 instructing it to reset the power failure information. The control calculation unit 65 performs control calculations using the sensor information. The non-volatile memory 67 stores the power failure information. The control unit 60 acquires power failure information from the rotation angle sensor 30 while the start switch 901 is off, stores the power failure information in the non-volatile memory 67, and then transmits a recovery signal to the rotation angle sensor 30. Note that the power failure information stored in the non-volatile memory 67 may have a different data format, for example, from that transmitted from the rotation angle sensor 30.

[0052] This allows the control unit 60 to be reset immediately after the start switch 901 is turned on, for example, due to a voltage drop caused by cranking, so that historical information relating to the power failure history can be retained on at least one of the rotation angle sensor 30 side and the non-volatile memory 67.

[0053] If a power failure occurs in the rotation angle sensor 30 while the start switch 901 is off, the control calculation unit 65 performs substitute information control using substitute information acquired from an external device 500 other than the rotation angle sensor 30. Information related to the substitute information control is stored in the non-volatile memory 67. This allows appropriate control to be performed even if a power failure occurs while the start switch 901 is off.

[0054] (Second embodiment) The second embodiment is shown in Figures 5 and 6. As described in the above embodiment, the control unit 60 stores the power failure information in the nonvolatile memory 67 and then transmits a recovery signal to the rotation angle sensor 30, so that the power failure information is retained even if the control unit 60 is reset.

[0055] If the non-volatile memory 67 is, for example, an EEPROM or flash memory, data is generally written after erasing the write area. However, if erasing the area takes time, there is a risk that the power failure information cannot be written during the time from when the IG is turned on until the starter starts up (approximately 0.6 seconds).

[0056] As shown in FIG. 5, the nonvolatile memory 67 of this embodiment has a plurality of virtual sectors 0 to n. Each virtual sector has a data area used to store validation information indicating whether the information in that sector is valid or invalid, management information for stored data, power failure information, and the like. When storing power failure information, as indicated by the arrows, virtual sectors are used in order starting from virtual sector 0. When virtual sector n is used up, information in at least some sectors other than the sector storing the most recent information (e.g., the final virtual sector n) is erased. Data erasure can be performed at any timing, but is preferably performed at a timing with ample time and computational load, such as when garbage collection is performed in the IG-OFF sequence.

[0057] The power failure information retention process of this embodiment will be described with reference to the flowchart of Fig. 6. The processes of S301 and S302 are the same as the processes of S201 and S202 in Fig. 4. If it is determined that power failure information has been acquired (S302: YES), the process proceeds to S303.

[0058] In S303, the control unit 60 searches for free sector X in the non-volatile memory 67. Here, the search is performed sequentially starting from virtual sector 0, and the first free area is designated as free sector X. In S304, the control unit 60 stores information relating to the presence or absence of a power failure in free sector X, and in S305, invalidates the sector (X-1) immediately preceding the current free sector X. In S306, the control unit 60 transmits a recovery signal to the rotation angle sensor 30, similar to S206 in FIG. 4.

[0059] In S307, the control unit 60 determines whether or not a power failure occurred to the rotation angle sensor 30 while the IG was off, similar to S207 in Fig. 4. If it is determined that there was no power failure (S307: NO), the control unit 60 proceeds to S308, and if there is correction information stored in the immediately preceding sector (X-1), the correction information is transferred to the free sector X to ensure information continuity. If it is determined that there was a power failure (S307: YES), the control unit 60 proceeds to S309, and performs substitution information control similar to S208 in Fig. 4. In addition, the correction information is stored in sector X where the power failure history is stored.

[0060] In this embodiment, a plurality of virtual sectors 0 to n for storing power failure information are provided in the nonvolatile memory 67, and free space for storing the power failure information is secured at the timing when the power failure information is acquired from the rotation angle sensor 30 when the IG is on. This reduces the time required for writing data.

[0061] Furthermore, sectors storing information other than the latest information are invalidated using flags, etc., and valid sector information is used in the angle calculation unit 64 and control calculation unit 65. This allows appropriate information to be used without having to erase data each time.

[0062] In this embodiment, the nonvolatile memory 67 is provided with a plurality of virtual sectors 0 to n. The control unit 60 stores the power failure information in an empty virtual sector and determines valid data by controlling the validation information. This reduces the time required to write the power failure information compared to when data is first erased from the write area and then written.

[0063] Furthermore, the control unit 60 erases data from at least one virtual sector excluding the area where valid data is stored during the period until the start switch 901 is turned off. The processing during the period until the start switch 901 is turned off also includes the IG-OFF sequence, which is the operation when the power is turned off. This ensures that free space is secured in the area that stores power failure information when the start switch 901 is turned on. This also provides the same effects as the above embodiment.

[0064] (Third embodiment) A third embodiment is shown in Figures 7 to 9. As shown in Figure 7, in this embodiment, a plurality of (two in the example of Figure 7) power failure information areas a and b are provided in the data area of ​​at least one virtual sector of nonvolatile memory 67. When using the virtual sector, the following description will be given assuming that, of the information areas a and b, the information area a is used preferentially.

[0065] The power failure information retention process of this embodiment will be described with reference to the flowchart of Fig. 8. The processes of S401 and S402 are the same as the processes of S201 and S202 in Fig. 4. In S403, which is performed if it is determined that power failure information has been acquired (S402: YES), the control unit 60 determines whether or not a power failure occurred to the rotation angle sensor 30 while the IG was off, similar to S207 in Fig. 4. If it is determined that a power failure occurred (S403: YES), the process proceeds to S406. If it is determined that no power failure occurred (S403: NO), the process proceeds to S404.

[0066] The control unit 60 searches for an empty sector X in S404, and stores the power failure information acquired this time, that is, information indicating that there is no power failure history, in the information area a of the empty sector X in S405.

[0067] In S406, the control unit 60 searches for the current valid sector Y. In the valid sector Y, power failure information is stored in information area a. In S407, the control unit 60 disables the validation flag in information area a of the valid sector Y. In S408, the control unit 60 stores the currently acquired information related to the power failure and correction information related to alternative control in information area b of the valid sector Y.

[0068] In S409, the control unit 60 determines whether the operating voltage is stable. Here, the voltage value itself, such as the battery voltage, may be monitored, or the operating voltage may be determined to be stable when, for example, the time required for cranking has elapsed. If it is determined that the operating voltage is not stable (S409: NO), this determination process is repeated. If it is determined that the operating voltage is stable (S409: YES), the process proceeds to S410.

[0069] In S410, the control unit 60 copies the information in the information area b of the current valid sector Y to the information area a of the free sector X. In S411, the control unit 60 invalidates the validation flag of the information area b of the current valid sector Y. In S412, the control unit 60 invalidates the current valid sector Y and validates the sector X to which the information has been copied.

[0070] The information read process will be described with reference to the flowchart in Figure 9. In S701, the control unit 60 searches for a valid sector in the non-volatile memory 67. In S702, the control unit 60 determines whether or not information area a of the searched valid sector is valid. If it is determined that information area a is valid (S702: YES), the process proceeds to S703, where the information in information area a is used for various controls, etc. If it is determined that information area a is invalid (S702: NO), the process proceeds to S704.

[0071] In S704, the control unit 60 determines whether or not information area b is valid. If it is determined that information area b is valid (S704: YES), the process proceeds to S705, and the information in information area b is used for various controls, etc. If it is determined that information area b is invalid (S704: NO), the process proceeds to S706. In S706, the control unit 60 issues an error notification because there is no valid data.

[0072] In this embodiment, each virtual sector of the nonvolatile memory 67 is configured to allow multiple writes of validation flags and power failure information. This allows appropriate storage of information without erasing data when power failure information is acquired. This also provides the same effects as the above embodiment.

[0073] (Fourth embodiment) The power failure information storage process of the fourth embodiment will be described with reference to the flowchart of Fig. 10. In this embodiment, the power failure information is stored and a restoration signal is transmitted avoiding the timing of cranking when a reset due to a voltage drop may occur.

[0074] The processes of S501 and S502 are the same as those of S201 and S202 in Fig. 4. In S503, the control unit 60 determines whether or not there is a power failure while the IG is off. In S504, similar to the process of S409 in Fig. 8, the control unit 60 determines whether or not the operating voltage is stable. If it is determined that the operating voltage is not stable (S504: NO), this determination process is repeated. If it is determined that the operating voltage is stable (S504: YES), the process proceeds to S505.

[0075] The processing of S505 is the same as the processing of S207 in Fig. 4. If it is determined that there has been no power failure (S505: NO), the process proceeds to S507, and if it is determined that there has been a power failure (S505: YES), the process proceeds to S506, where alternative information control is performed. Here, as with S208 in Fig. 4, the alternative information control involves absolute angle calculation using external information and correction processing to align the reference position when the vehicle is traveling straight.

[0076] In S507, the control unit 60 stores the power failure information and information related to substitution information control, such as correction values ​​in the event of a power failure, in the nonvolatile memory 67. Any method for storing information in the nonvolatile memory 76 may be used, and the methods of the second and third embodiments, for example, may be adopted. The same applies to S609 in FIG. 11 .

[0077] In S508, the control unit 60 transmits a return signal to the rotation angle sensor 30. In Fig. 8, after cranking is completed, the return signal is stored in the nonvolatile memory and continuously transmitted, but the return signal may be transmitted at any timing after cranking is completed, and may be transmitted, for example, in the IG off sequence when there is ample time.

[0078] After the voltage drop period caused by the driving of other devices that share the battery 900 has ended, the control unit 60 stores the power supply failure information in the nonvolatile memory 67 and then transmits a recovery signal to the rotation angle sensor 30. Note that the presence or absence of a power supply failure is determined even during the voltage drop period. This allows the power supply failure information to be retained on the rotation angle sensor 30 side even if the control unit 60 is reset due to a drop in battery voltage caused by cranking, for example.

[0079] The communication unit 69 may be configured to transmit a return signal to the rotation angle sensor 30 during the power-off operation process when the start switch 901 is turned off. This is the same as for the return signal transmission in the above embodiment. This reduces the calculation load immediately after the start switch 901 is turned on, which is relatively large. This also provides the same effects as the above embodiment.

[0080] (Fifth embodiment) The power failure information retention process according to the fifth embodiment will be described with reference to the flowchart in FIG. 11. In this embodiment, the volatile memory 356 of the rotation angle sensor 30 is provided with multiple memory areas p and q. In the event of a power failure, the multiple memory areas p and q are simultaneously reset to their initial value "0," thereby setting a flag. Furthermore, resetting the power failure flag by restoring it to the normal value "1" can be performed individually for each memory area p and q. Here, the description will be given assuming that there is one memory area p and one memory area q, but there may be multiple memory areas p and q, and the number of areas may be different.

[0081] Steps S601 and S602 are the same as steps S201 and S202 in Fig. 4. If it is determined that power failure information has been acquired (YES at step S602), the process proceeds to step S603, in which the control unit 60 transmits a restoration signal to the memory area p. As a result, in the rotation angle sensor 30, if the power failure has been resolved, the memory area p is restored to the normal value "1."

[0082] On the other hand, if the power failure continues due to a disconnection of the battery power line Lb or the like, the memory area p will maintain the initial value "0." Note that even if the power failure continues, the rotation angle sensor 30 can operate if power is supplied via the IG when the IG is turned on. Also, at this stage, the recovery process for the memory area q is not performed, and if the power failure occurred while the IG was off and the initial value is "0," that state will be maintained.

[0083] In S604, the control unit 60 determines whether or not a power failure occurred to the rotation angle sensor 30 while the IG was off. If it is determined that there was no power failure while the IG was off (S604: NO), the process proceeds to S609, where information regarding the presence or absence of a power failure is stored in the non-volatile memory 67. If it is determined that there was a power failure while the IG was off (S604: YES), the process proceeds to S605.

[0084] In S605, the control unit 60 reads the power failure flag in the memory area p from the rotation angle sensor 30. In S606, the control unit 60 determines whether the power failure flag in the memory area p is set. If it is determined that the power failure flag is set (S606: YES), the process proceeds to S611. If it is determined that the power failure flag is not set (S606: NO), the process proceeds to S607.

[0085] In S607, since the power failure flag in the memory area p is reset by the transmission of the recovery signal, the control unit 60 determines that the rotation angle sensor 30 has a history of a power failure while the IG was off, and that the power failure has been resolved.

[0086] The control unit 60 performs substitution information control in S608, and stores information regarding the presence or absence of a power failure and information such as correction values ​​in the event of a power failure in the nonvolatile memory 67 in S609. In S610, the control unit 60 transmits a recovery signal to the memory area q. The timing of transmitting the recovery signal to the memory area q can be any timing as long as it is after the data has been stored in the nonvolatile memory 67.

[0087] In S611, which is reached if the power failure flag in the memory area p remains set even after the recovery signal is sent (S606: YES), the control unit 60 determines that the power failure continues in the rotation angle sensor 30. In S612, the control unit 60 takes measures to deal with the abnormality, and in S613, stores in the non-volatile memory 67 abnormality information indicating that the power failure in the rotation angle sensor 30 continues.

[0088] In this embodiment, after transmitting the recovery signal, the control unit 60 reacquires the power failure information from the rotation angle sensor 30 and determines, based on the reacquired power failure information, whether the power failure continues in the rotation angle sensor 30. If the power failure flag is not reset even after transmitting the recovery signal, it can be confirmed that the power failure state continues.

[0089] The power failure determination circuit 355 has a volatile memory 356 provided with multiple storage areas for storing power failure information. When a power failure occurs, the multiple storage areas simultaneously store information reporting the power failure. Note that "simultaneously" means that a delay sufficient to record the occurrence of the power failure is allowed. Furthermore, the multiple storage areas can be reset at different times depending on the recovery signal.

[0090] Furthermore, the control unit 60 transmits a restoration signal to some of the storage areas before storing the power failure information in the nonvolatile memory 67. This makes it possible to quickly determine whether or not there has been a power failure in the rotation angle sensor 30 while the ignition is off. Even if the control unit 60 is reset due to a voltage drop caused by cranking before storing the power failure information in the nonvolatile memory 67, the power failure information in the memory area q is retained, and therefore, by acquiring the power failure information again after resetting the control unit 60, it is possible to properly acquire information related to the power failure while the ignition is off.

[0091] Furthermore, by checking the state of the power failure flag in the memory area p to which the recovery signal was sent before storing the power failure information in the nonvolatile memory 67, it is possible to quickly determine whether the power failure continues in the rotation angle sensor 30. This also provides the same effects as the above embodiment.

[0092] In the embodiment, the rotation angle sensor 30 corresponds to the "sensor unit," the angle calculation unit 352 and the rotation count calculation unit 353 correspond to the "sensor information calculation unit," the volatile memory 356 corresponds to the "storage unit," the communication unit 359 corresponds to the "sensor-side communication unit," the communication unit 69 corresponds to the "control unit-side communication unit," and the motor 80 corresponds to the "controlled object." Furthermore, the correction information corresponds to the "information related to substitution information control."

[0093] (Other embodiments) In the above embodiment, one control unit is provided for one rotation angle sensor, resulting in a mixed analog-digital configuration. In other embodiments, there may be multiple combinations of rotation angle sensors and control units, the detection value of one rotation angle sensor may be shared by multiple control units, or multiple rotation angle sensors may be provided for one control unit. Furthermore, communication between the rotation angle sensor and the control unit is not limited to mixed analog-digital communication, and may be digital communication only.

[0094] In the above embodiment, the sensor device detects the rotation of the motor. In other embodiments, the sensor device may be a sensor other than the motor rotation angle sensor, such as a torque sensor or a steering sensor.

[0095] In the above embodiment, the motor is a three-phase brushless motor. In other embodiments, the motor unit is not limited to a three-phase brushless motor, and may be any type of motor. Furthermore, the motor unit is not limited to a motor (electric motor), and may be a generator, or a so-called motor generator that combines the functions of an electric motor and a generator. In the above embodiment, the sensor device is applied to an electric power steering device. In other embodiments, the sensor device may be applied to a device other than an electric power steering device.

[0096] The present invention may be characterized as follows, for example: "The sensor device according to any one of claims 1 to 4, wherein the nonvolatile memory is provided with a plurality of virtual sectors, and the control unit stores the power failure information in an empty virtual sector and determines valid data by controlling validation information," "The sensor device according to any one of claims 1 to 6, wherein the control unit, after transmitting the recovery signal, reacquires the power failure information from the sensor unit, and determines whether the power failure in the sensor unit continues based on the reacquired power failure information," and "The sensor device according to any one of claims 1 to 7, wherein the power failure determination circuit has a storage unit (356) provided with a plurality of memory areas for storing the power failure information, and when the power failure occurs, information indicating the occurrence of the power failure is simultaneously stored in the plurality of memory areas, and each area can be reset at a different timing in response to the recovery signal."

[0097] The control unit and the method described herein may be implemented by a special-purpose computer configured by configuring a processor and memory programmed to execute one or more functions embodied in a computer program. Alternatively, the control unit and the method described herein may be implemented by a special-purpose computer configured by configuring a processor with one or more dedicated hardware logic circuits. Alternatively, the control unit and the method described herein may be implemented by one or more special-purpose computers configured by combining a processor and memory programmed to execute one or more functions with a processor configured with one or more hardware logic circuits. Furthermore, the computer program may be stored in a computer-readable non-transitory tangible recording medium as instructions to be executed by a computer. As described above, the present invention is not limited to the above embodiments and can be embodied in various forms without departing from the spirit of the invention. [Explanation of symbols]

[0098] 1. Sensor device 30: Rotation angle sensor (sensor unit) 31 to 33: Detection element 352: Angle calculation unit (sensor information calculation unit) 353... Rotational speed calculation unit (sensor information calculation unit) 355: Power failure detection circuit 356: Volatile memory (storage unit) 359 Communication unit (sensor side communication unit) 60: Control unit 65: Control calculation unit 67: Non-volatile memory 69: Communication unit (control unit side communication unit) 80 Motor (detection target) 900 Battery 901 Start switch

Claims

1. a sensor unit (30) including: detection elements (31-33) that detect a change in a physical quantity according to the operation of a detection target (80); a power supply failure determination circuit (355) that can determine a power supply failure in which power is no longer supplied from a battery power supply line (Lb) that does not pass through a start switch (901); and a sensor side communication unit (359) that transmits sensor information including power supply failure information relating to whether or not the power supply failure has occurred, and that can continue at least a part of its operation by power supply from the battery power supply line even while the start switch is turned off; a control unit (60) that operates on power supplied via the start switch and includes a control unit side communication unit (69) that receives the sensor information from the sensor unit and transmits a recovery signal to the sensor unit to instruct the reset of the power supply failure information, a control calculation unit (65) that performs control calculations using the sensor information, and a nonvolatile memory (67) that stores the power supply failure information; Equipped with The control unit acquires the power failure information from the sensor unit while the start switch is turned off, stores the power failure information in the non-volatile memory, and then transmits the recovery signal to the sensor unit.

2. When the power supply failure occurs in the sensor unit while the start switch is turned off, the control calculation unit performs substitution information control using substitution information acquired from an external device (500) other than the sensor unit, The sensor device according to claim 1 , wherein the nonvolatile memory stores information related to the substitution information control.

3. 3. The sensor device according to claim 1, wherein the control unit stores the power failure information in the nonvolatile memory after a period of voltage drop caused by driving another device that shares the battery (900) has ended.

4. 3. The sensor device according to claim 1, wherein the control unit side communication unit transmits the recovery signal to the sensor unit during a power-off operation process when the start switch is turned off.

5. The nonvolatile memory is provided with a plurality of virtual sectors, The sensor device according to claim 1 , wherein the control unit stores the power failure information in the empty virtual sector and determines valid data by controlling validation information.

6. 6. The sensor device according to claim 5, wherein the control unit erases data from at least one of the virtual sectors excluding a portion where valid data is stored, during the period until the start switch is turned off.

7. The sensor device according to claim 1, wherein the control unit, after transmitting the recovery signal, reacquires the power failure information from the sensor unit, and determines whether the power failure continues in the sensor unit based on the reacquired power failure information.

8. The power supply failure determination circuit has a storage unit (356) provided with a plurality of memory areas for storing the power supply failure information, The sensor device according to claim 1 or 7, wherein when the power failure occurs, information indicating that the power failure has occurred is simultaneously stored in the plurality of memory areas, and each area can be reset at different times in response to the recovery signal.

9. The sensor device according to claim 8 , wherein the control unit transmits the recovery signal for the part of the memory area before storing the power failure information in the nonvolatile memory.

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