Communication Systems

Abstract

To provide a communication system that ensures simultaneity of a plurality of sensor values transmitted via a plurality of communication paths with a simple configuration.SOLUTION: A first receiving unit 501 of a microcomputer 70 has a plurality of signal acquisition units 61A, 61B and one transmission trigger signal generator 63B. The plurality of signal acquisition units 61A and 61B are connected to sensor elements 31A and 31B of a corresponding sensor device 301 via individual communication paths 41A and 41B, and acquire sensor values S1A and S1B transmitted via the communication paths 41A and 41B when the communication paths 41A and 41B are ready for transmission. The one transmission trigger signal generator 63B generates a common transmission trigger signal Trc1 so that the plurality of communication paths 41A and 41B become ready for transmission simultaneously. In the first receiving unit 501, the plurality of signal acquisition units 61A and 61B can simultaneously acquire the plurality of sensor values S1A and S1B by the common transmission trigger signal Trc1.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to communication systems. [Background technology]

[0002] 2. Description of the Related Art Conventionally, there has been known a communication system in which a microcomputer receives sensor values ​​detected redundantly by a plurality of sensors and performs control calculations based on the sensor values.

[0003] For example, in a communication system applied to an electric power steering device, a microcomputer calculates a torque value from multiple sensor values ​​transmitted from a torque sensor, and calculates an assist amount based on the torque value. In such a communication system, if the synchronicity of each sensor value is not maintained, the microcomputer may calculate an incorrect torque or erroneously detect an abnormality in the sensor value.

[0004] For example, in the detection device disclosed in Patent Document 1, two microcomputers each generate a trigger signal that requests the transmission of a sensor value. However, due to differences in the calculation timing of each microcomputer, the timing of the trigger signal may differ, and sensor values ​​with different timing may be acquired. Therefore, in this detection device, one microcomputer monitors the trigger signal of the other microcomputer, and adjusts the transmission timing of its own trigger signal so that the transmission timing of the trigger signals of the two microcomputers coincides. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2018-106513 A Summary of the Invention [Problem to be solved by the invention]

[0006] In the conventional technology of Patent Document 1, the timing of sending trigger signals is adjusted between microcomputers, so extra computing power is required. In addition, assume a configuration in which multiple communication modules corresponding to multiple sensor values ​​sent from, for example, a torque sensor are provided in one microcomputer. In this configuration, if trigger signals are output individually from the trigger signal generating unit of each communication module to the communication path through which each sensor value is sent, there is a problem that the number of signal output terminals of the microcomputer and the number of wiring man-hours increase.

[0007] The present invention has been created in consideration of the above-mentioned points, and its object is to provide a communication system that ensures the simultaneity of multiple sensor values ​​transmitted via multiple communication paths with a simple configuration. [Means for solving the problem]

[0008] The communication system of the present invention includes one or more sensor devices (301, 302) and one or more microcomputers (70, 701, 702). The sensor device includes a plurality of sensor elements (31A, 31B, 32A, 32B) that detect a sensor value of a certain physical quantity from a same detection target.

[0009] The microcomputer has one or more receiving units (501, 502), physical quantity calculation units (77, 771, 772), and control quantity calculation units (78, 781, 782). The receiving units are provided corresponding to the sensor device, and receive signals including sensor values ​​transmitted from multiple sensor elements of the sensor device.

[0010] The physical quantity calculation unit calculates a physical quantity based on a plurality of sensor values. The control quantity calculation unit calculates a predetermined control quantity using the physical quantity. For example, in the case of a communication system applied to an electric power steering device, the physical quantity is a steering torque and the control quantity is an assist quantity.

[0011] One receiving unit has a plurality of signal acquiring units (61A, 61B, 62A, 62B) and one transmission trigger signal generating unit (63B, 64B).

[0012] The multiple signal acquisition units are connected to the sensor elements of the corresponding sensor devices via individual communication paths (41A, 41B, 42A, 42B), and acquire the sensor values ​​transmitted via the communication paths when the communication paths are in a state where transmission is possible. One transmission trigger signal generation unit generates a common transmission trigger signal so as to make the multiple communication paths in a state where transmission is possible simultaneously. In one receiving section, a plurality of signal acquiring sections can simultaneously acquire a plurality of sensor values ​​in response to a common transmission trigger signal.

[0013] In one aspect of the present invention, the signal acquisition unit is configured as a module in combination with a trigger signal generation unit that generates a trigger signal. A trigger signal generation unit (63B, 64B) of a representative module (51B, 52B), which is one of a plurality of modules included in one receiving unit, functions as the transmission trigger signal generation unit. A communication system according to another aspect of the present invention includes a plurality of sensor devices, and a microcomputer has a plurality of receiving units corresponding to the plurality of sensor devices. The transmission trigger signal generation units of the plurality of receiving units are configured to generate transmission trigger signals in synchronization with each other.

[0014] As a result, in the present invention, the microcomputer can ensure the simultaneity of multiple sensor values ​​acquired from the sensor device. This prevents the microcomputer from calculating an incorrect physical quantity based on sensor values ​​acquired at different times, or from erroneously detecting an abnormality in the sensor value. In addition, since one transmission trigger signal is output per receiving unit, the number of signal output terminals of the microcomputer and the amount of wiring work can be reduced, resulting in a simple configuration. [Brief description of the drawings]

[0015] [Figure 1] 1 is a schematic block diagram of a communication system according to a first embodiment. [Diagram 2] FIG. 2 is a block diagram of a microcomputer in the communication system according to the first embodiment. [Diagram 3] 1 is a schematic configuration diagram of an electric power steering device to which a communication system is applied. [Figure 4] 5 is a timing chart illustrating the relationship between a trigger signal and transmission of a sensor value. [Diagram 5] FIG. 4A is a sensor characteristic diagram of a first sensor device, and FIG. 4B is a sensor characteristic diagram of a second sensor device. [Figure 6] 5 is a flowchart showing a process performed by a first abnormality determination unit. [Figure 7] 6 is a flowchart showing a process performed by a second abnormality determination unit. [Figure 8] 5 is a flowchart showing a process performed by a torque calculation unit. [Figure 9] FIG. 11 is a schematic block diagram of a communication system according to a second embodiment. [Figure 10] FIG. 11 is a block diagram of a microcomputer in a communication system according to a second embodiment. [Figure 11] FIG. 1 is a schematic block diagram of a communication system of a comparative example. [Figure 12] 1 is a flowchart of a synchronization process according to a reference comparative example equivalent to Patent Document 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, multiple embodiments of the communication system of the present invention will be described with reference to the drawings. Components that are substantially the same in the first and second embodiments will be given the same reference numerals and will not be described. The first and second embodiments will be collectively referred to as "the present embodiment." The communication system of the present embodiment is applied to an electric power steering device, and calculates an assist amount based on the steering torque of the driver detected by a sensor device.

[0017] (First embodiment) A communication system 100 according to a first embodiment will be described with reference to Figs. 1 to 8. First, the system configuration will be described with reference to Figs. 1 and 2. The communication system 100 according to the first embodiment includes two sensor devices 301, 302 that are provided redundantly, and one microcomputer 70. Hereinafter, a unit of components corresponding to one sensor device will be referred to as a "system." The communication system according to this embodiment has a two-system configuration. Fig. 1 mainly shows the communication configuration between the sensor devices 301, 302 and the microcomputer 70, and Fig. 2 mainly shows the configuration of the microcomputer 70.

[0018] The sensor device 301 of the first system is referred to as the "first sensor device 301," and the sensor device 302 of the second system is referred to as the "second sensor device 302." In addition, in the microcomputer 70, the components corresponding to the first sensor device 301 are marked with "first," and the components corresponding to the second sensor device 302 are marked with "second," to distinguish between them. Since the configurations of the first and second systems are similar, the first system will be mainly described, and the description of the second system will be omitted as appropriate. The omitted parts of the second system can be interpreted by replacing the reference numerals "1" in the description of the first system with "2."

[0019] The first sensor device 301 has a plurality of sensor elements 31A, 31B that detect a sensor value of the driver's steering torque as a "certain physical quantity" from the same detection target. In this embodiment, the first sensor device 301 has two sensor elements 31A, 31B. In FIG. 1, the sensor element indicated by the reference symbol 31A is denoted as "sensor element 1A," and the sensor element indicated by the reference symbol 31B is denoted as "sensor element 1B." In addition, the sensor values ​​of the steering torque detected by the sensor elements 31A, 31B are denoted as S1A, S1B, respectively.

[0020] For example, when Hall elements, which are magnetic detection elements, are used as the sensor elements 31A and 31B, a Hall IC, which is a package including the Hall elements, corresponds to the sensor device 301. The sensor elements 31A and 31B detect the magnetic displacement of a magnetic flux collecting ring based on the torsion angle of the torsion bar in the steering torque sensor 93 shown in Fig. 3, convert the magnetic flux collecting ring into a voltage signal, and output the voltage signal. In this example, the magnetic flux collecting ring corresponds to the "detection target." Note that magnetic detection elements other than Hall elements or elements that detect changes other than magnetism may be used as the sensor elements 31A and 31B.

[0021] The sensor device 301 of this embodiment transmits a sensor signal including information on sensor values ​​S1A, S1B detected by the sensor elements 31A, 31B as a digital signal via the communication paths 41A, 41B at a fixed transmission period. In detail, a nibble signal conforming to the Society of Automotive Engineers standard SAE-J2716, a so-called SENT (Single Edge Nibble Transmission) type signal, is used as the sensor signal. The sensor device 301 is driven in an SPC (Short PWM Code) mode that applies the SENT communication method, and starts communication by a trigger signal from the microcomputer 70. Note that a transmission circuit, an operating power supply line, a reference potential line, etc. are not shown in FIG. 1.

[0022] The microcomputer 70 includes two systems of receiving units 501, 502 and abnormality determination units 761, 762 provided corresponding to the sensor devices 301, 302, and a torque calculation unit 77 and an assist amount calculation unit 78 provided in common to the two systems. The torque calculation unit 77 corresponds to the "physical amount calculation unit", and the assist amount calculation unit 78 corresponds to the "control amount calculation unit".

[0023] The configurations of the first and second systems in the microcomputer 70 are also similar, so the first system will be mainly described and the description of the second system will be omitted as appropriate. Regarding the trigger signal generating units, the trigger signal generating units of the first system are denoted by reference characters "63A, 63B" and the trigger signal generating units of the second system are denoted by reference characters "64A, 64B". The trigger signal generating units of the two systems of receiving units 501, 502 are configured to generate trigger signals, which will be described later, in synchronization with each other by a timer in one microcomputer 70.

[0024] The first receiving unit 501 receives signals including sensor values ​​S1A, S1B transmitted from the sensor elements 31A, 31B of the first sensor device 301. The first receiving unit 501 has two signal acquiring units 61A, 61B and two trigger signal generating units 63A, 63B. Particularly in this embodiment, the signal acquiring units 61A, 61B are configured as a SENT module together with the trigger signal generating units 63A, 63B.

[0025] The SENT module 51A corresponding to the sensor element 31A has a signal acquiring unit 61A and a trigger signal generating unit 63A. The SENT module 51B corresponding to the sensor element 31B has a signal acquiring unit 61B and a trigger signal generating unit 63B. In Figures 1 and 2, the SENT module designated by reference numeral 51A is referred to as "SENT module 1A," and the SENT module designated by reference numeral 51B is referred to as "SENT module 1B."

[0026] The signal acquiring units 61A and 61B are connected to the sensor elements 31A and 31B of the corresponding sensor device 301 via individual communication paths 41A and 41B. When the communication paths 41A and 41B are in a state where transmission is possible, the signal acquiring units 61A and 61B acquire the sensor values ​​SiA and S1B transmitted via the communication paths 41A and 41B. Both of the trigger signal generating units 63A and 63B generate trigger signals. However, as described below, the trigger signal generating units 63A and 63B use the generated trigger signals in different ways.

[0027] Here, of the two SENT modules 51A, 51B included in the first receiving unit 501, one SENT module 51B is defined as a "representative module", and the SENT module 51A other than the representative module is defined as a "general module".

[0028] The trigger signal generated by the trigger signal generating unit 63B of the SENT module 51B, which is the representative module, is output to the communication paths 41A, 41B as a "transmission trigger signal Trc1" common to the first system. The common transmission trigger signal Trc1 puts the two communication paths 41A, 41B in a state in which transmission is possible simultaneously. In other words, the trigger signal generating unit 63B of the representative module functions as one "transmission trigger signal generating unit" in the first receiving unit 501. In the first receiving unit 501, the two signal acquiring units 61A, 61B can simultaneously acquire the sensor values ​​S1A, S1B by the common transmission trigger signal Trc1.

[0029] The trigger signal generated by the trigger signal generating unit 63B is also used as an "intra-module trigger signal" that transitions the signal acquiring unit 61B in the own module 51B to a reception-enabled state. In other words, the trigger signal generated by the trigger signal generating unit 63B of the representative module 51B is used as a "transmission trigger signal that also serves as an intra-module trigger signal."

[0030] On the other hand, the trigger signal generated by the trigger signal generating unit 63A of the SENT module 51A, which is a general module, is used only as an "intra-module trigger signal" that transitions the signal acquiring unit 61A in the own module 51A to a receivable state. Because the generated trigger signal is not used as a transmission trigger signal for the corresponding communication path 41A, the operation by the trigger signal generating unit 63A of the general module is an operation in which a trigger signal in SPC mode is generated but not output to the communication path 41A, and is therefore commonly referred to as "empty firing." The effects of this configuration will be described later in comparison with a comparative example.

[0031] Next, the first abnormality determination unit 761 determines whether the sensor values ​​S1A, S1B transmitted from the sensor elements 31A, 31B of the first sensor device 301 are abnormal. Similarly, the second abnormality determination unit 762 determines whether the sensor values ​​S2A, S2B transmitted from the sensor elements 32A, 32B of the second sensor device 302 are abnormal. The processing by the first and second abnormality determination units 761, 762 will be described later with reference to FIGS.

[0032] The torque calculation unit 77 calculates the steering torque based on the multiple sensor values ​​S1A, S1B, S2A, S2B received by the two systems of receiving units 501, 502 and the abnormality information determined by the abnormality determination units 761, 762. The processing by the torque calculation unit 77 will be described later with reference to Fig. 8. The assist amount calculation unit 78 calculates the assist amount output by the motor 80 as a "predetermined control amount" based on the steering torque calculated by the torque calculation unit 77.

[0033] Here, referring to FIG. 3, a schematic configuration of an electric power steering device to which the communication system 100 is applied will be described. The electric power steering device 90 shown in FIG. 3 is of a column assist type, but the present invention can be similarly applied to a rack assist type electric power steering device. A steering shaft 92 is connected to a steering wheel 91. A pinion gear 96 provided at the tip of the steering shaft 92 meshes with a rack shaft 97. A pair of wheels 98 are provided at both ends of the rack shaft 97 via tie rods or the like. When a 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 the linear motion of the rack shaft 97 by the pinion gear 96, and the pair of wheels 98 are steered to an angle corresponding to the amount of displacement of the rack shaft 97.

[0034] The electric power steering device 90 includes a steering torque sensor 93, an ECU (control device) 700, a motor 80, a reduction gear 94, etc. The steering torque sensor 93 is provided midway along the steering shaft 92 and detects the steering torque of the driver. The steering torque sensor 93 of this embodiment redundantly includes two sensor devices 301, 302. In addition to the sensor devices 301, 302, the steering torque sensor 93 also includes a torsion bar, a multi-pole magnet, a magnetic yoke, a magnetic collecting ring, etc. These configurations are well known and therefore will not be illustrated.

[0035] The ECU 700 is composed of a microcomputer 70 and pre-drivers (not shown), and is equipped with a CPU, a ROM, a RAM, an I / O, and bus lines connecting these components, etc. The ECU 700 executes control by software processing by executing a program stored in advance in the CPU, and hardware processing by a dedicated electronic circuit.

[0036] An assist amount calculation unit 78 of the microcomputer 70 calculates an assist amount (assist torque command) to be output by the motor 80 based on a sensor value acquired from a steering torque sensor 93, and controls energization of the motor 80 accordingly. The motor 80 is configured as, for example, a three-phase brushless motor. The assist torque output by the motor 80 is transmitted to a steering shaft 92 via a reduction gear 94. The motor 80 may be configured integrally with the ECU 700.

[0037] As a conventional technique in the technical field of communication systems as described above, Patent Document 1 (JP Patent Publication No. 2018-106513) discloses a detection device that synchronizes the transmission timing of a trigger signal in SENT communication using two microcomputers. The flowchart in FIG. 12 shows synchronization processing according to a reference comparative example equivalent to Patent Document 1. In the following explanation of the flowchart, the symbol "S" means step. The left column of FIG. 12 shows the processing of the first microcomputer, and the right column shows the processing of the second microcomputer.

[0038] The first microcomputer transmits a trigger signal to the sensor S1#N in S911, and receives a sensor value (measurement data) from the sensor S1#N in S921. The second microcomputer transmits a trigger signal to the sensor S2#N in S912, and receives a sensor value (measurement data) from the sensor S2#N in S922. Here, the sensor S1#N and the sensor S2#N have the same measurement target, and synchronicity of the sensor values ​​is required. However, because the transmission timing of S911 and S912 is based on the calculation timing of each microcomputer, a discrepancy in the transmission timing may occur.

[0039] Therefore, the second microcomputer monitors the timing of sending a trigger signal from the first microcomputer in S93, and adjusts the timing of sending a trigger signal from the second microcomputer so that the timings of sending the trigger signals from both microcomputers coincide in S94. This ensures the simultaneity of the sensor values ​​from the sensors S1#N and S2#N.

[0040] However, in Patent Document 1, for example, the measurement targets of the multiple sensors S1#1 to #N corresponding to the first microcomputer are not the same. In other words, a configuration in which multiple sensor values ​​for the same measurement target are acquired by different signal acquisition units in one microcomputer, as in this embodiment, is not disclosed. If the idea of ​​Patent Document 1 were applied to the trigger signal transmission timing between the multiple SENT modules 51A and S52A in the first receiving unit 501 of this embodiment, additional computing power would be required for the microcomputer. In contrast, this embodiment aims to ensure the simultaneity of sensor values ​​without increasing computing power.

[0041] Next, the timing of signals transmitted from the sensor elements 31A and 31B to the communication paths 41A and 41B will be described with reference to the timing chart in Fig. 4. In the text, the reference symbols for the first system are used. The same applies to the timing of signals transmitted from the sensor elements 32A and 32B of the second system to the communication paths 42A and 42B.

[0042] For example, switching elements are provided between the communication paths 41A and 41B and the ground. When a trigger signal is turned ON and input to the gate of the switching element, the switching element becomes conductive, and the current passing through the communication paths 41A and 41B flows to the ground, interrupting the transmission. When the trigger signal is turned OFF, the switching element is cut off, and the communication paths 41A and 41B become capable of transmission. In other words, each of the communication paths 41A and 41B becomes capable of transmission when the trigger signal input to the gate of the switching element provided in each of the communication paths 41A and 41B is turned ON once and then turned OFF. In this configuration example, in this embodiment, the trigger signal input to the gate of the switching element is defined as a "transmission trigger signal."

[0043] However, there may be a timing discrepancy between the trigger signals generated by the two SENT modules 51A and 51B in one receiving unit 501. In the example shown in Fig. 4, there is a time δ difference between the timing ta when the trigger signal of the SENT module 51A turns ON and then OFF, and the timing tb when the trigger signal of the SENT module 51B turns ON and then OFF.

[0044] Here, the configuration of a communication system 109 of a comparative example will be described with reference to Fig. 11. In the communication system 109 of the comparative example, transmission trigger signals Tr1A, Tr1B are individually output from the trigger signal generating units 63A, 63B of the SENT modules 51A, 51B of the first receiving unit 501 to the corresponding communication paths 41A, 41B. Similarly, transmission trigger signals Tr2A, Tr2B are individually output from the trigger signal generating units 64A, 64B of the SENT modules 52A, 52B of the second receiving unit 502 to the corresponding communication paths 42A, 42B.

[0045] Therefore, for example, if the timing of the transmission trigger signals Tr1A and Tr1B in the first system is shifted, the signal acquirers 61A and 61B may acquire sensor values ​​at different timings from the sensor elements 31A and 31B, which may cause the microcomputer 70 to calculate an incorrect torque or erroneously detect an abnormality in the sensor value.

[0046] In addition, in the comparative example, it is necessary to output the transmission trigger signals Tr1A and Tr1B individually to the communication paths 41A and S1B through which the sensor values ​​S1A and S1B are transmitted, which causes an increase in the number of signal output terminals and connection man-hours of the microcomputer 70. In the comparative example shown in Fig. 11, two terminals are required to output the transmission trigger signals Tr1A and Tr1B from the first receiving unit 501.

[0047] In contrast, in this embodiment, the trigger signal of the SENT module 51A, which is a general module, is used only as an intra-module trigger signal that transitions the signal acquisition unit 61A to a receivable state, and does not function as a transmission trigger signal that transitions the communication path 41A to a transmittable state. On the other hand, the trigger signal of the SENT module 51B, which is a representative module, is used as an intra-module trigger signal that transitions the signal acquisition unit 61B to a receivable state, and is also used as a transmission trigger signal that transitions both communication paths 41A and 41B to a transmittable state. Therefore, the timing ta is ignored, and signal transmission from the sensor elements 31A and 31B to the signal acquisition units 61A and 61B is started simultaneously, triggered by the timing tb at which the common transmission trigger signal is turned ON and then OFF.

[0048] The signals from the sensor elements 31A and 31B are output as a series of signals in one frame, consisting of a Cal & Sync signal, a Status signal, a Sensor Data signal, a CRC signal, and an End signal. The SENT method is a transmission method that enables bidirectional communication using 4-bit nibble signals. The size of the sensor data signal, which includes the steering torque sensor values ​​S1A and S1B, is 3 nibbles (12 bits), and can be up to two values ​​from "000" to "FFF". 12 It is possible to transmit up to 4096 different data values. The signal acquisition units 61A and 61B receive SENT signals and acquire sensor values ​​S1A and S1B contained in the signals.

[0049] As described above, in this embodiment, in one receiving unit 501, the two signal acquiring units 61A, 61B can simultaneously acquire two sensor values ​​S1A, S1B by the common transmission trigger signal Trc1. This ensures the simultaneity of the multiple sensor values ​​S1A, S1B acquired by the microcomputer 70 from the sensor device 301. This prevents the microcomputer 70 from calculating an erroneous torque or erroneously detecting an abnormality in the sensor values ​​based on sensor values ​​acquired at different times.

[0050] In addition, in this embodiment, one transmission trigger signal Trc1 is output for one receiving unit 501, so that it is possible to reduce the signal output terminals of the microcomputer 70 and the wiring man-hours. That is, as shown in Fig. 1 and Fig. 2, only one terminal is required to output the transmission trigger signal Trc1 from the first receiving unit 501. Therefore, it is possible to achieve a simple configuration.

[0051] Next, the processing by the first and second abnormality determination units 761, 762 will be described with reference to Fig. 5 to Fig. 7. As shown in Fig. 5(a) and (b), normal sensor values ​​S1A, S1B, S2A, S2B take values ​​within a specified range of 0 to 4095, excluding a lower limit range near 0 and an upper limit range near 4095. The lower limit and upper limit ranges excluded here are "outside the specified range." If the sensor values ​​S1A, S1B, S2A, S2B are outside the specified range, they are determined to be abnormal.

[0052] In this embodiment, the two sensor values ​​from the two sensor elements of each system have cross characteristics. One sensor value in the cross characteristics is a positive characteristic sensor value having a linear output characteristic with a positive correlation to the actual torque. The other sensor value in the cross characteristics is a negative characteristic sensor value having a linear output characteristic with a negative correlation with the actual torque, the absolute value of the slope of which is equal to that of the positive characteristic sensor value.

[0053] For example, in the first sensor device 301, the sensor value S1B corresponds to the positive characteristic sensor value, and the sensor value S1A corresponds to the negative characteristic sensor value. In the second sensor device 302, the sensor value S2A corresponds to the positive characteristic sensor value, and the sensor value S2B corresponds to the negative characteristic sensor value. The positive characteristic sensor value and the negative characteristic sensor value are symmetrical values ​​centered on 2048, and the sum of the positive characteristic sensor value and the negative characteristic sensor value is 4096. If the sum of the positive characteristic sensor value and the negative characteristic sensor value falls outside a predetermined range around 4096, the abnormality determination units 761, 762 determine that at least one sensor value is abnormal.

[0054] In S51 of Fig. 6, the first abnormality determination unit 761 acquires the sensor values ​​S1A and S1B. In S52, it is determined whether the sensor values ​​S1A and S1B are outside the specified range shown in Fig. 5(a) or whether the absolute value of the difference between the sum of the sensor values ​​S1A and S1B and 4096 is equal to or greater than the deviation threshold. If YES in S52, the first abnormality determination unit 761 determines in S53 that the first sensor device 301, which outputs at least one abnormal sensor value, is abnormal. If NO in S52, the first abnormality determination unit 761 determines in S54 that the first sensor device 301 is normal.

[0055] As in Fig. 6, in S61 in Fig. 7, the second abnormality determination unit 762 acquires the sensor values ​​S2A and S2B. In S62, it is determined whether the sensor values ​​S2A and S2B are outside the specified range shown in Fig. 5(b) or whether the absolute value of the difference between the sum of the sensor values ​​S2A and S2B and 4096 is equal to or greater than the deviation threshold. If the result is YES in S62, the second abnormality determination unit 762 determines in S63 that the second sensor device 302, which outputs at least one abnormal sensor value, is abnormal. If the result is NO in S62, the second abnormality determination unit 762 determines in S64 that the second sensor device 302 is normal.

[0056] For example, in the case of abnormality determination based on the sum of the sensor values ​​of the cross characteristics, if the simultaneity of the sensor values ​​is not ensured, there is a possibility of erroneously detecting an abnormality. In this embodiment, the simultaneity of the sensor values ​​is ensured by using the common transmission trigger signals Trc1 and Trc2, thereby preventing erroneous detection of an abnormality.

[0057] Next, the processing by the torque calculation unit 77 will be described with reference to FIG. 8. In S71, the torque calculation unit 77 acquires four sensor values ​​S1A, S1B, S2A, and S2B. In S72, the torque calculation unit 77 converts the sensor values, which are dimensionless numbers ranging from 0 to 4095, into torque values ​​T1 and T2 [Nm] of each system using equations (1) and (2). Kt is a conversion gain. The sign of the conversion gain Kt is appropriately determined according to the definition of positive and negative torque values ​​and sensor values. In this embodiment, T1 and T2 have values ​​with opposite signs.

[0058] T1 = (S1A - S1B) × Kt (1) T2 = (S2A - S2B) × Kt (2)

[0059] In S73 and S74, the presence or absence of an abnormality is determined for the sensor devices 301 and 302. When the abnormality determination units 761 and 762 determine that either of the sensor devices is abnormal, the microcomputer 70 continues the calculation using only the sensor values ​​of the sensor devices in the normal system. Note that in Fig. 8, it is assumed that a double failure in which both the sensor devices 301 and 302 fail will not occur.

[0060] If the abnormality determination unit 761 determines that the first sensor device 301 is abnormal, YES is determined in S73, and the process proceeds to S75. In S75, the torque value (-T2) of the second system is adopted as the steering torque. If the abnormality determination unit 762 determines that the second sensor device 302 is abnormal, NO is determined in S73 and YES is determined in S74, and the process proceeds to S76. In S76, the torque value T1 of the first system is adopted as the steering torque.

[0061] If both the sensor devices 301, 302 are normal, NO is determined in S73 and YES is determined in S74, and the process proceeds to S77. In S77, the average value ((T1-T2) / 2) of the torque values ​​of the two systems is adopted as the steering torque.

[0062] In the formulas (1) and (2), the torque value is calculated based on the difference between the sensor values, so if the simultaneity of the sensor values ​​is not ensured, there is a possibility that erroneous torque values ​​T1 and T2 will be calculated. In this embodiment, the simultaneity of the sensor values ​​is ensured by using common transmission trigger signals Trc1 and Trc2, thereby preventing erroneous torque values ​​from being calculated.

[0063] Second embodiment A communication system 200 according to the second embodiment will be described with reference to Fig. 9 and Fig. 10. Fig. 9 and Fig. 10 correspond to Fig. 1 and Fig. 2 of the first embodiment, respectively. The communication system 200 according to the second embodiment includes two microcomputers 701, 702 for each system corresponding to the two systems of sensor devices 301, 302. The microcomputers 701, 702 for the two systems each include receiving units 501, 502, abnormality determination units 761, 762, torque calculation units 771, 772, and assist amount calculation units 781, 782, respectively.

[0064] The first microcomputer 701 calculates a steering torque T1 in a torque calculation unit 771 based on sensor values ​​S1A, S1B acquired from two sensor elements 31A, 31B of the first sensor device 301, and calculates an assist amount in an assist amount calculation unit 781. The second microcomputer 702 calculates a steering torque T2 in a torque calculation unit 772 based on sensor values ​​S2A, S2B acquired from two sensor elements 32A, 32B of the second sensor device 302, and calculates an assist amount in an assist amount calculation unit 782.

[0065] The microcomputers 701, 702 communicate information with each other through inter-microcomputer communication. As a result, the trigger signal generating units 63B, 64B of the two receiving units 501, 502 generate transmission trigger signals Trc1, Trc2 in synchronization with each other. Furthermore, the torque calculation units 771, 772 calculate steering torque based on abnormality information determined by the abnormality determination units 761, 762 of the own system and the other system. The calculation results of the torque calculation units 771, 772 and the assist amount calculation units 781, 782 are reconciled as necessary.

[0066] In the communication system 200 of the second embodiment, the microcomputers 701 and 702 are provided redundantly, so that even if one of the microcomputers is abnormal, the calculation of the assist amount can be continued using the calculation result of the normal microcomputer.

[0067] (Other embodiments) (a) One sensor device may have three or more sensor elements, and one receiving unit of a microcomputer may have three or more signal acquisition units corresponding thereto. For example, one receiving unit corresponding to three sensor elements may be composed of one representative module and two general modules. The transmission trigger signal generated by the trigger signal generating unit of the representative module is distributed to three communication paths, making the three communication paths capable of transmitting simultaneously.

[0068] (b) The communication system is not limited to having two systems, and may have one system or three or more systems of sensor devices and receiving units. In a communication system having a single system, it is sufficient that a common transmission trigger signal between one sensor device and one receiving unit enables multiple signal acquiring units to simultaneously acquire multiple sensor values. In addition, when a microcomputer is provided for each of three or more systems, the system may be configured so that the transmission trigger signals of each microcomputer are generated in synchronization with each other through communication between the three or more microcomputers.

[0069] (c) For example, the signal acquirers 61A and 61B of the first receiving unit 501 do not have to be configured as a module together with the trigger signal generators 63A and 63B. Furthermore, the means for putting the signal acquirers 61A and 61B into a reception-enabled state is not limited to the intra-module trigger signal from the trigger signal generators 63A and 63B. In the case where the signal acquirers 61A and 61B are configured not to require an intra-module trigger signal, the trigger signal generator 63A that does not function as a transmission trigger signal generator may not be required.

[0070] (d) In cases where the possibility of an abnormality occurring in the sensor value is substantially zero, or where there is no impact even if an abnormality occurs, the microcomputer does not need to include an abnormality determination unit, etc. Furthermore, the characteristics of the two sensor values ​​are not limited to cross characteristics, and may be characteristics that both have a positive correlation or both have a negative correlation with the actual physical quantity.

[0071] (e) The physical quantity detected by the sensor element and calculated by the physical quantity calculation unit of the microcomputer is not limited to torque, but may be any physical quantity such as a rotation angle, stroke, speed, load, pressure, etc. Accordingly, the control quantity calculated by the control quantity calculation unit of the microcomputer using the physical quantity is not limited to the assist amount, but may be a current command value, a rotation speed command value, etc., which are appropriately set.

[0072] (f) The digital communication method (protocol) of the communication system is not limited to the SENT method, and other protocols may be adopted. The sensor signal is not limited to a 4-bit nibble signal, and an 8-bit octet signal or the like may be used. In addition, the sensor device may transmit the sensor value to the receiving unit of the microcomputer as an analog signal.

[0073] (g) The communication system of the present invention may be applied to any device that calculates a control amount based on detected sensor values, in addition to an electric power steering device.

[0074] As described above, the present invention is not limited to the above-described embodiment, and can be embodied in various forms without departing from the spirit of the present invention.

[0075] The control device and the method described in the present disclosure may be realized by a special-purpose computer provided by configuring a processor and a memory programmed to execute one or more functions embodied in a computer program. Alternatively, the control device and the method described in the present disclosure may be realized by a special-purpose computer provided by configuring a processor with one or more dedicated hardware logic circuits. Alternatively, the control device and the method described in the present disclosure may be realized by one or more special-purpose computers configured by a combination of a processor and a memory programmed to execute one or more functions and a processor configured with one or more hardware logic circuits. In addition, the computer program may be stored in a computer-readable non-transitory tangible recording medium as instructions executed by a computer. [Explanation of symbols]

[0076] 100, 200... communication systems, 301, 302: Sensor device, 31A, 31B, 32A, 32B: Sensor element, 41A, 41B, 42A, 42B...communication path, 501, 502: Receiving units, 61A, 61B, 62A, 62B...signal acquisition section, 63B, 64B: Trigger signal generating unit (transmission trigger signal generating unit), 70, 701, 702...Microcomputer, 77, 771, 772: Torque calculation unit (physical quantity calculation unit), 78, 781, 782... Assist amount calculation unit (control amount calculation unit).

Claims

1. one or more sensor devices (301, 302) each having a plurality of sensor elements (31A, 31B, 32A, 32B) for detecting a sensor value of a certain physical quantity from the same detection target; one or more microcomputers (70, 701, 702) provided corresponding to the sensor device, each having one or more receiving units (501, 502) for receiving signals including the sensor values ​​transmitted from the plurality of sensor elements of the sensor device, physical quantity calculation units (77, 771, 772) for calculating the physical quantity based on the plurality of sensor values, and control quantity calculation units (78, 781, 782) for calculating a predetermined control quantity using the physical quantities; Equipped with One of the receiving units is a plurality of signal acquisition units (61A, 61B, 62A, 62B) connected to the sensor elements of the corresponding sensor devices via individual communication paths (41A, 41B, 42A, 42B), and configured to acquire the sensor values ​​transmitted via the communication paths when the communication paths are in a transmission enabled state; one transmission trigger signal generating unit (63B, 64B) that generates a common transmission trigger signal so that the plurality of communication paths are simultaneously in a transmission enabled state; and In one of the receiving units, the plurality of signal acquiring units can simultaneously acquire the plurality of sensor values ​​in response to the common transmission trigger signal, the signal acquisition unit is configured as a module together with a trigger signal generation unit that generates a trigger signal; A communication system in which the trigger signal generating unit (63B, 64B) of a representative module (51B, 52B) that is one of the multiple modules included in one receiving unit functions as the transmission trigger signal generating unit.

2. In a general module (51A, 52A) that is a module other than the representative module among the plurality of modules included in one receiving unit, the trigger signal generated by the trigger signal generating unit (63A, 64A) is used as an intra-module trigger signal that transitions the signal acquiring unit in the module to a reception-enabled state; 2. The communication system according to claim 1, wherein in the representative module, the trigger signal generated by the trigger signal generating section is used as the transmission trigger signal that also serves as the intra-module trigger signal.

3. The sensor device includes a plurality of systems, and the microcomputer includes a plurality of systems of the receiving unit corresponding to the plurality of systems of the sensor device, 3. The communication system according to claim 1, wherein the transmission trigger signal generating sections of the receiving sections of the plurality of systems are configured to generate the transmission trigger signals in synchronization with each other.

4. a plurality of sensor devices (301, 302) each having a plurality of sensor elements (31A, 31B, 32A, 32B) for detecting a sensor value for a certain physical quantity from the same detection target; one or more microcomputers (70, 701, 702) provided corresponding to the sensor devices of the plurality of systems, each having a plurality of receiving units (501, 502) for receiving signals including the sensor values ​​transmitted from the plurality of sensor elements of the sensor devices, a physical quantity calculation unit (77, 771, 772) for calculating the physical quantity based on the plurality of sensor values, and a control quantity calculation unit (78, 781, 782) for calculating a predetermined control quantity using the physical quantity; Equipped with One of the receiving units is a plurality of signal acquisition units (61A, 61B, 62A, 62B) connected to the sensor elements of the corresponding sensor devices via individual communication paths (41A, 41B, 42A, 42B), and configured to acquire the sensor values ​​transmitted via the communication paths when the communication paths are in a transmission enabled state; one transmission trigger signal generating unit (63B, 64B) that generates a common transmission trigger signal so that the plurality of communication paths are simultaneously in a transmission enabled state; and In one of the receiving units, the plurality of signal acquiring units can simultaneously acquire the plurality of sensor values ​​in response to the common transmission trigger signal, A communication system in which the transmission trigger signal generating units of the receiving units of a plurality of systems are configured to generate the transmission trigger signals in synchronization with each other.

5. 5. The communication system according to claim 1, wherein the microcomputer further comprises an abnormality determination unit (761, 762) that determines abnormality in the plurality of sensor values ​​transmitted from the plurality of sensor elements.

6. the plurality of sensor values ​​from the plurality of sensor elements include positive characteristic sensor values ​​(S1B, S2A) having linear output characteristics with a positive correlation with respect to an actual physical quantity, and negative characteristic sensor values ​​(S1A, S2B) having linear output characteristics with a negative correlation with respect to the actual physical quantity, the absolute value of the slope of which is equal to that of the positive characteristic sensor values, 6. The communication system according to claim 5, wherein the abnormality determination unit determines that at least one of the sensor values ​​is abnormal when the sum of the positive characteristic sensor value and the negative characteristic sensor value falls outside a predetermined range.

7. The sensor device includes a plurality of systems, and the microcomputer includes a plurality of systems of the receiving unit corresponding to the plurality of systems of the sensor device, When the abnormality determination unit determines that any of the sensor values ​​is abnormal, 7. The communication system according to claim 5, wherein the microcomputer continues calculations using only the sensor values ​​of the sensor devices in the normal system.

8. 8. The communication system according to claim 1, wherein the sensor device transmits the plurality of sensor values ​​as SENT signals conforming to Society of Automotive Engineers standard SAE-J2716.

9. The communication system according to any one of claims 1 to 8, which is applied to an electric power steering device (90) of a vehicle, wherein the sensor device detects a steering torque of a driver, and the microcomputer calculates an assist amount to be output by a motor (80) based on the steering torque detected by the sensor device.

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