JP5218018B2 - Sensor device - Google Patents

Description

  The present invention is a sensor device that can be mounted on a vehicle, and in particular, is connected to a main communication device provided in an ECU device via a pair of communication lines to enable construction of mutual communication and supply of power to the sensor device. A sensor that detects a predetermined physical quantity and outputs an electrical signal in analog form, and A / D converts the output signal of the sensor into an A / D register and stores the converted digital value in an A / D register. The present invention relates to a sensor device including a converter and configured to transmit the digital value stored in the A / D register from the slave communication device to the ECU device via the pair of communication lines.

  In recent years, with the advancement of technology and functionality of vehicle control, various sensor devices for acquiring information inside and outside the vehicle are mounted on the vehicle, and the installation sites are arranged at multiple locations according to the control purpose. Has been. As such a sensor device, for example, a sensor device including an acceleration detection sensor, a pressure detection sensor, an ultrasonic sensor, an acoustic sensor, an optical fiber sensor, and the like is applicable, and detection information detected by the sensor device is the same device. After being converted from an analog signal to a digital signal by a converter provided therein, it is transmitted to an electronic control device (ECU device) and contributes to the amount of control information for achieving a predetermined control purpose. As an example, a collision impact or the like is calculated based on an acceleration detection sensor disposed in the vehicle so that a collision impact with the vehicle can be detected, and the output signal of the detection sensor transmitted (incorporated into an ECU device). An occupant protection device (such as an air bag system) that operates by an arithmetic processing function. In the vehicle control means configured with a predetermined sensor device based on the control purpose, the wiring connection between the ECU device and the sensor device forms a differential communication path using a pair of communication lines, and the ECU device is mainly used. It is known to configure master-slave communication (master / slave communication) having a function and a sensor device as a slave function. For example, in JP 2003-46655 A (Publication 1), an ECU device is a master node, a sensor A two-wire differential communication device is shown in which mutual communication using the device as a slave node and power supply from the ECU device to the sensor device are possible.

Here, as described above, the signal format transmitted / received between the ECU device / sensor device, which can configure the master-slave communication relationship via the pair of communication lines, is obtained by converting the analog detection amount into a digital signal, Consideration has been given to wiring resistance in the vehicle and environmental resistance (noise resistance, electromagnetic environmental characteristics, etc.) during operation. However, when an analog signal detected by a predetermined sensor is converted into a predetermined amount of digital signal, a problem caused by the digital output value after A / D conversion indicating an abnormal value (for example, malfunction of an occupant protection device) Etc.) may occur. Specifically, a specific bit of the output register after A / D conversion is fixed to “0” or “1” regardless of the input value, so-called bit fixation may occur. . Japanese Patent Application Laid-Open No. 2003-37501 (Cited Document 2) discloses such a failure detection method relating to A / D conversion, and a voltage corresponding to the power supply voltage Vcc and the ground voltage E with respect to the A / D input circuit. A method is disclosed in which a plurality of multiplexers to which a source can be applied is provided and register bit sticking after A / D conversion is detected.
JP 2003-46655 PR JP 2003-37501 A

  In the method for detecting bit sticking disclosed in the cited document 2, the digital data after conversion is applied by applying a voltage that exactly matches the power supply voltage Vcc and the ground voltage E of the A / D converter from a plurality of multiplexers. There is an advantage that bit sticking can be detected for digital data output by setting all bits to “1” or “all bits to“ 0 ””.

  However, in the technique disclosed in the cited document 2, the digital output value after conversion is determined by binary values of “all bits are“ 1 ”” or “all bits are“ 0 ””. If the applied voltage value fluctuates due to noise or the like on the D converter side, bit sticking may be detected erroneously.

  The present invention has been made in view of the above problems, and is connected to a main communication device provided in an ECU device via a pair of communication lines to enable mutual communication construction and power supply to the sensor device. A sensor provided with a slave communication device for detecting a predetermined physical quantity and outputting an electrical signal in analog form, and A / D conversion for A / D converting the output signal of the sensor and storing the converted digital value in an A / D register A sensor device configured to transmit the digital value stored in the A / D register from the slave communication device to the ECU device via the pair of communication lines. An object of the present invention is to provide a sensor device capable of detecting bit sticking with improved accuracy.

The invention according to claim 1, which has been made in order to solve the above-mentioned problems, is a slave communication device connected to a main communication device provided in an ECU device via a pair of communication lines to enable mutual communication and power supply. A sensor that detects a predetermined physical quantity and outputs an electrical signal in analog form, and an A / D converter that A / D converts the output signal of the sensor and stores the converted digital value in an A / D register, A sensor device configured to transmit the digital value stored in the A / D register from the slave communication device to the ECU device via the pair of communication lines;
Pseudo signal generation means for generating a signal similar to that output by the sensor as a pseudo signal;
Switching means for switching the input to the A / D converter between the output signal of the sensor and the pseudo signal of the pseudo signal generating means;
The pseudo signal of the pseudo signal generating means is input to the A / D converter through switching by the switching means, and a digital value after A / D conversion is read from the A / D register, and the pseudo signal is converted into the pseudo signal. Bit abnormality detecting means for detecting a bit abnormality of the A / D register by determining whether or not the value is within a corresponding predetermined range.

  By providing such a configuration, a slave communicator connected to a main communicator provided in the ECU device via a pair of communication lines and capable of mutual communication and power supply, and a predetermined physical quantity are detected. A sensor for outputting an electrical signal in analog form, and an A / D converter for A / D converting the output signal of the sensor and storing the converted digital value in an A / D register, stored in the A / D register Even if the sensor device is configured to transmit a digital value from the slave communication device to the ECU device via a pair of communication lines, the sensor device enables detection of bit abnormality (bit fixation) with improved detection accuracy. Can be provided.

  That is, a signal similar to the sensor (analog) output constituting the sensor device is generated as a pseudo signal, and this pseudo signal output is input to the A / D converter via the input path switching means for the sensor output signal. Then, the digital output value after the A / D conversion is read, and it is determined whether or not the value is within a predetermined range corresponding to the pseudo signal, thereby detecting a bit abnormality (bit fixing) of the A / D converter provided in the sensor device. ) Can be detected. In addition, the voltage output corresponding to the physical quantity detected by the sensor and the pseudo signal are input to the A / D converter by switching the input path. Therefore, the analog signal input is not conscious of the processing configuration of the A / D converter. It is possible to detect bit abnormality (bit fixation) as an A / D conversion function from digital signal output to digital signal output.

  According to a second aspect of the present invention, in the sensor device according to the first aspect, the pseudo signal generation unit generates the pseudo signal while sequentially changing a voltage level within a predetermined range. The digital value after A / D conversion based on the pseudo signal input from the pseudo signal generation means is sequentially read out from the A / D register to determine whether the value is within a predetermined range corresponding to each pseudo signal. It is characterized by.

  By providing such a configuration, it is possible to detect a bit abnormality for each bit of the A / D register. For example, in a sensor device configured to detect a vehicle collision, a collision impact is detected. Even in a sensor output area that can be determined to be received, it is possible to detect a bit abnormality (bit fixation) related to the output bit area of the corresponding A / D register. Furthermore, it is possible to detect a bit abnormality that occurs after the sensor device is attached to the vehicle.

The invention according to claim 3 detects a predetermined physical quantity, a slave communicator connected to a main communicator provided in the ECU device through a pair of communication lines and capable of mutual communication and power supply. A sensor that outputs an electrical signal in analog form, and an A / D converter that A / D converts the output signal of the sensor and stores the converted digital value in an A / D register, and is stored in the A / D register A sensor device configured to transmit the digital value from the slave communication device to the ECU device via the pair of communication lines,
A test value generating means for generating a predetermined digital value corresponding to the output bit length of the A / D register as a test value; and an input to the A / D converter as an output signal of the sensor and the test value generating means. Switching means for switching between the inspection values, and writing the inspection value of the inspection value generating means to the A / D register via switching by the switching means, and reading out the digital value from the A / D register Bit abnormality detecting means for detecting a bit abnormality of the A / D register by determining a match with the inspection value.

  By having such a configuration, it becomes possible to perform bit abnormality (bit fixation) detection of the A / D converter with an inspection value composed of digital data, and further improve the inspection accuracy, downsize, It is possible to provide a sensor device suitable for cost reduction.

  According to a fourth aspect of the present invention, in the sensor device according to the third aspect, the inspection value includes a first fixed value corresponding to an output bit length of the A / D register, and the first fixed value. It may be configured to include a second fixed value in a complement relationship. By providing such a configuration, it is possible to execute bit abnormality (bit fixation) for all the bits of the A / D register with the first and second fixed values, thereby simplifying the bit abnormality detection means.

  According to a fifth aspect of the present invention, in the sensor device according to any one of the first to fourth aspects, the driving power of the sensor is generated based on the power supplied via the slave communication device. It is characterized by that. By providing such a configuration, the same effect as the above-described bit abnormality detection can be obtained even when the vehicle body ground potentials of the sensor device and the ECU device are different.

  According to a sixth aspect of the present invention, in the sensor device according to any one of the first to fifth aspects, the abnormality detection is performed during an initialization process after power is turned on via the pair of communication lines. The bit abnormality detection of the A / D register is performed by means. When starting up after boarding the vehicle, it is possible to detect a bit abnormality and ensure safety.

  A seventh aspect of the present invention is the sensor device according to any one of the first to sixth aspects, wherein the sensor device is mounted on a vehicle together with the ECU device, and the sensor is an acceleration detection sensor or a pressure detection sensor. It is configured by any one of a sensor, an ultrasonic sensor, an acoustic sensor, and an optical fiber sensor. It becomes possible to adapt to various detection sensors, and the function as a sensor device can be expanded.

  Hereinafter, embodiments of the sensor device of the present invention will be specifically described with reference to the drawings.

<First embodiment>
FIG. 1A is an arrangement schematic diagram of a sensor device equipped with an acceleration detection sensor as a sensor device of the present invention when mounted on a vehicle, and is a top view in which the upper side is the front of the vehicle.

  As shown in FIG. 1A, the sensor devices (2a to 2f) are arranged at a plurality of locations inside the vehicle 1 in accordance with the control purpose. In this embodiment, the sensor device (2a to 2f) is provided with an acceleration detection sensor for the purpose of protecting passengers when a vehicle collision occurs. Therefore, the left and right two locations (2a and 2b) are on the front side in the vehicle traveling direction. Furthermore, in order to detect acceleration in the left-right direction at the front seating position of the vehicle occupant, two locations (2c, 2d) on the side of the vehicle, and to detect lateral acceleration at the rear seating position, Sensor devices are arranged at two locations (2e, 2f) on the side.

  A sensor device (2a to 2f) including an acceleration detection sensor disposed inside the vehicle 1 is connected to an electronic control device (ECU device) 3 by wiring. The sensor devices (2a, 2b) disposed on the front side in the vehicle traveling direction are connected to the sensor devices (2c, 2d) disposed on the side of the vehicle at the front seating position by connection wires (100a, 100b). The sensor devices (2c, 2d) disposed on the side of the vehicle at the rear seating position are connected to the ECU device 3 by connection wires (100c, 100d) by wires (100c, 100d). The sensor devices (2c, 2e) and the sensor devices (2d, 2f) are daisy chain connected.

  The acceleration amount detected by each of the sensor devices (2a to 2f) is generated by a calculation function (not shown) provided in the ECU device 3 to generate a control command for occupant protection in accordance with a predetermined purpose. When the vehicle collision is detected based on the output of the sensor device (2a, 2b) disposed on the front side in the vehicle traveling direction, the airbag device 4 protects the driver and protects the front passenger (passenger seat). Protects passengers by activating the airbag device 5 (6a, 6b) for protecting the occupant from the airbag device 5 and the glass pieces that are destroyed or scattered by collision impact (ignit the squib of the airbag device) Can be achieved. Similarly, when an abnormal state is detected based on the output of the sensor device (2c to 2f) disposed on the side of the vehicle at the front / rear seating position, for example, the seat belt pre-tensioner device (7a to 7a). 7d) can be activated to ensure safety such that passengers in the front and rear seats do not jump out of the vehicle.

  As in the present embodiment, the ECU device 3 having a calculation function according to a predetermined vehicle control purpose and a sensor for detecting the vehicle state according to the control purpose (pressure detection sensor, ultrasonic sensor, acoustic sensor, optical fiber sensor, etc. In connection with the sensor devices (2a to 2f) equipped with a), the wiring resistance in the vehicle and the environmental resistance (noise resistance, temperature characteristics, electromagnetic environmental characteristics, etc.) during vehicle operation are taken into consideration. The analog detection amount detected by the sensor is generally converted into a digital signal and transmitted, and the vehicle state information converted by the A / D converter provided on the sensor device (2a to 2f) side is a predetermined amount. Is communicated by digital data.

  FIG. 1B shows a schematic configuration diagram showing a connection form between the ECU device 3 and the sensor device 2, and connection between the devices (ECU device 3 / sensor devices (2a to 2f)). A simple one-to-one connection form is shown as a representative form.

  As is clear from the configuration diagram shown in FIG. 1B, the ECU device 3 includes the main communication device 8, and sensor detection information (vehicle state) transmitted via the main communication device 8. Based on the information, for example, vehicle control calculation (not shown) for the purpose of passenger protection and the like is performed, and activation and control of the airbag device and the like are executed.

  The main communicator 8 includes an input / output circuit (not shown) and a communication control circuit, and forms a so-called master / slave node communication relationship with the slave communicator 9 provided in the plurality of sensor devices 2. Mutual communication that functions as a node is realized.

  As shown in FIG. 1A, the sensor device 2 has various sensors (pressure detection sensor, ultrasonic sensor, acoustic sensor, optical fiber sensor, etc.) that detect the vehicle state in accordance with a predetermined control purpose. In this embodiment, the acceleration detection sensor 21 is provided. The detected acceleration quantity (analog signal), which is a physical quantity, is input to an A / D converter 11 included in the slave communication device 9 and converted into a digital value composed of a predetermined bit amount. The converted digital value is temporarily stored in a register 11b (A / D register) included in the A / D converter 11, and then the ECU device via the slave communication device 9 having a master / slave communication relationship with the ECU device 3. 3 is transmitted. The slave communication device 9 includes a power supply circuit 10 for driving the detection sensor 21.

  The slave communication device 9 includes an input / output circuit (not shown) and a communication control circuit, forms a so-called master / slave node communication relationship with the main communication device 8 provided in the ECU device 3, and functions as a communication slave node. Mutual communication is realized.

  Here, the main communication device 8 provided in the ECU device 3 and the slave communication device 9 provided in the sensor device 2 are connected to each other via a connection terminal (8a, 8b) and a connection terminal (9a, 9b). By wiring connection with the line 100, mutual communication by the differential method is enabled. Then, between the main communication device 8 and the slave communication device 9, power is supplied to the plurality of slave communication devices 9 within a power supply range of a power supply circuit (not shown) provided in the ECU device 3. The power supply between the main communication device 8 and the slave communication device 9 is also supplied to the sensor device 2 via the pair of communication lines 100, and the sensor device 2 operates based on this power.

  A schematic diagram of the power supply and mutual communication by the differential method between the main communication device 8 and the slave communication device 9 is shown in FIG. 2A, where the vertical axis represents voltage value and the horizontal axis represents time. A potential waveform generated between the slave communication device 9 connection terminals (9a, 9b) is shown. As is apparent from the schematic diagram shown in FIG. 2A, after the power supply from the main communication device 8 to the slave communication device 9 is executed, the main communication device 8 communicates with the communication master node and the slave communication device 9. Mutual communication with the slave node is executed. As described above, power is supplied from the main communication device 8 to the slave communication device 9 to the plurality of sensor devices 2 within a range where a power supply circuit (not shown) provided in the ECU device 3 can supply power. In the figure, the power supply and mutual communication states for four or more sensor devices 2 (six sensor devices (2a to 2f) shown in FIG. 1A) are shown.

  Returning to the configuration diagram shown in FIG. 1B, the power supply circuit 10 is a power supply circuit that generates driving power for the acceleration detection sensor 21 based on the power supplied from the ECU device 3 via the slave communication device 9. Function.

  The acceleration detection sensor 21 is a known sensor, and operates with the power supply generated by the power supply circuit 10. FIG. 2B shows a graph showing the relationship between the acceleration amount (G) detected by the acceleration detection sensor 21 and the voltage value (analog signal) as the sensor output signal, and the vertical axis indicates the sensor output. The voltage (V) and the horizontal axis are the detected acceleration amount (G). As is apparent from the graph, the sensor output voltage value is output in accordance with the acceleration amount (+ X, −X) G that increases or decreases on both the positive and negative sides around 0G, and the effective region of the detected acceleration amount is constant. It is limited in a proportional region having an inclination (the output voltage and the detected acceleration amount are in a proportional relationship). That is, even if the output voltage value indicates “0 V”, the acceleration value that is effective as a detection amount is not necessarily indicated. Naturally, the output voltage value (V) effective as the acceleration sensor 21 is in the range of “Z to Vcc-y”, and since the detected acceleration amount and the output voltage value have a proportional relationship, “Vcc / 2 ″ corresponds to 0G.

  In general, in an acceleration sensor that detects a collision impact at the time of a vehicle collision, the acceleration value detected at the time of sudden start / acceleration or sudden stop of the vehicle is about ˜G, while the occupant protection device is activated. An acceleration value of 10G or more is detected at the time of a vehicle collision.

  Therefore, in the graph of output voltage / detected acceleration shown in FIG. 2B, rather than the vicinity of “Vcc / 2” relative to 0 G, it can be determined that it will have been subjected to a collision impact, −X / + X It is important from the viewpoint of safety protection to surely detect the voltage values in the vicinity of the opposite "Z" and "Vcc-y".

  Returning to the configuration diagram shown in FIG. 1B again, the output voltage value of the acceleration detection sensor 21 is input to the A / D converter 11 and converted into a digital quantity relative to the output voltage value. The A / D converter 11 is a known converter and includes a sample hold 11a that samples an input voltage value at a predetermined timing and a register 11b that stores and stores the converted digital quantity. In order to improve acceleration detection accuracy at the time, a converter of about 10 bits is used.

  Therefore, as described above, in the sensor device 2 including the acceleration sensor that detects the collision impact at the time of the vehicle collision, the vehicle suddenly starts and stops rather than the voltage value in the vicinity of “Vcc / 2” relative to 0G. It is important to reliably detect an acceleration amount of several G or more detected during acceleration or sudden stop. That is, in the A / D converter 11, it is important to reliably convert and output an acceleration amount of a predetermined amount or more, rather than a digital amount relative to the vicinity of 0G, and is not output except when a vehicle collision occurs. It is also important for ensuring safety during normal operation to reduce such bit region anomalies (bit sticking). In other words, detecting an A / D converter bit abnormality (bit stuck) is necessary to ensure safety in an emergency (such as when a collision occurs), and malfunctions during normal operation (during normal operation) (normal operation) This is necessary to prevent accidental operation of occupant protection devices, etc.

  Next, the first embodiment of the present invention will be described in detail with reference to FIGS. 3A and 4. In addition, in the code | symbol shown in Fig.3 (a), the structure to which the code | symbol same as FIG.1 (b) is attached | subjected is a common structure, and the structure which attached | subjected the code | symbol different in the following description is centered. Explained.

  FIG. 3A is a schematic configuration diagram showing a one-to-one connection form between the ECU device 3 and the sensor device 2 including the pseudo signal generation unit 12 in the first embodiment. FIG. 4 shows a flowchart of the bit abnormality (bit fixation) detection means in this embodiment.

  As shown in FIG. 3 (a), the pseudo signal generator 12 stores the storage memory 12a in which predetermined data is written in advance and the D / A conversion for converting the digital output value of the storage memory 12a into a corresponding analog voltage value. It comprises a device 12b and switching devices (SW1, SW2). Here, the storage memory 12a and the D / A converter 12b function as pseudo signal generation means described in the claims, and the switchers (SW1, SW2) are sensors input to the A / D converter 11. It functions as switching means for switching the signal / pseudo signal path.

  The storage memory 12a stores digital data corresponding to each bit amount of the A / D converter 11 in advance, and is configured by a general-purpose storage memory such as EPROM. The digital data stored in advance is relative to the register output value after A / D conversion. As an example, the register 11b (A / D register) included in the A / D converter 11 has a 10-bit amount. In this case, a value in which each bit is “1” is written such as “001h, 002h, 004h, 008h, 010h, 020h, 040h, 080h, 100h, 200h”.

  The D / A converter 12b is composed of a general-purpose product having a function of converting and generating a digital output value of the storage memory 12a into a corresponding analog voltage value. The generated analog signal (voltage value) is applied to a sample hold 11 a included in the A / D converter 11.

  The switches (SW1, SW2) are composed of general-purpose products such as silicon switches, and switch the signal input path to the A / D converter 11, that is, the pseudo signal (analog signal) generated by the pseudo signal generator 12 and the acceleration. It functions as switching means for switching the output signal of the detection sensor 21.

  Thus, by providing the sensor device 2 with the pseudo signal generation unit 12, the voltage output corresponding to the acceleration amount that is a physical quantity detected by the acceleration detection sensor 21, and the bit included in the register 11b of the A / D converter 11 By switching the voltage output of a pseudo signal corresponding to the amount and applying it to the sample hold 11a, a bit abnormality (bit) as a conversion processing function of the A / D converter 12 (system from the sample hold 11a input to the register 11b) is detected. Detection).

  Next, the bit abnormality detection means using the pseudo signal generation unit 12 of this embodiment will be described according to the flowchart shown in FIG.

  As shown in FIG. 2A, the sensor device 2 in the present embodiment is supplied with power supply power required for operation by the ECU device 3 connected via a pair of communication lines 100. Therefore, the flowchart shown in FIG. 4 is executed at least in the communication phase period executed after the power feeding phase shown in FIG.

  The bit fixation of the A / D converter 11 which is a problem to be solved by the present invention is mainly caused by the initial failure of the A / D converter itself, and as is apparent from the graph shown in FIG. , Bit sticking in the vicinity of 0G is detected and removed with high accuracy in the process of attaching the sensor device 2 to the vehicle 1. However, in the area near “−X / + X” where it can be determined that a collision impact would have been received, an acceleration amount of 10 G or more is required. Even after the sensor device 2 is mounted, there is a risk that bit sticking may occur during another assembly process.

  Therefore, in order to reliably detect such a bit abnormality (bit fixation), the bit abnormality detection means shown in FIG. 4 is executed immediately after the start of the communication phase shown in FIG. It is desirable that Specifically, it is desirable to be executed in an initialization process at the time of establishment of mutual communication performed between the main communication device 8 and the slave communication device 9 immediately after completion of the power feeding phase. It is possible to detect a bit abnormality at the stage of initial operation (for example, turning operation of the ignition key) in which the driver starts sitting on the vehicle seat, thereby ensuring early safety.

  Returning to the flowchart shown in FIG. 4, the above-described power feeding phase is completed between the sensor device 2 and the ECU device 3, and the master / slave communication relationship between the master communication device 8 and the slave communication device 9 is established. The transition to establishment is the activation of the bit abnormality detection means (step S1, “START”).

  After establishment of the predetermined establishment process, an execution command for bit abnormality detection is transmitted from the ECU device 3, and the slave communication device 9 receives the execution command based on a predetermined protocol (step S2). The slave communication device 9 that has received the execution command replaces the switching devices (SW1, SW2) constituting the pseudo signal generation unit 12 shown in FIG. 3A with the pseudo signal ( The input path is switched (SW1 / OFF, SW2 / ON; step S3) so that the voltage value is applied to the A / D converter 11, and the digital data (A / D) previously written in the storage memory 12a A corresponding analog signal (voltage value) is generated via the D / A converter 12b based on each bit value of the converter 11 (step S4).

  The analog signal (voltage value) of the pseudo signal generated by the D / A converter 12b is input to the sample hold 11a of the A / D converter 11 included in the sensor device 2, and is sampled and converted at a predetermined timing. Digital data is stored and held in the register 11b. The digital data stored and held in the register 11b is transmitted to the ECU device 3 via the slave communication device 9 (step S5), and it is determined whether or not the output data is within a specified value (step S6). Here, “within a specified value” refers to a range that takes into account, for example, noise fluctuations superimposed on a communication path or the like.

  If it is not within the specified value in step S6 (step S6, “NO”), it is determined that a bit abnormality (bit fixation) has been detected, and it is determined that the product of the A / D converter 11 is defective (step S8, “NO”). Anomaly detection ”).

  The determination shown in step S6 is executed over the entire bit length of the A / D converter 11. That is, a pseudo signal is generated while sequentially changing the voltage level of the pseudo signal within a predetermined range, and the digital value after A / D conversion based on the inputted pseudo signal is sequentially read out from the register 11b, and each pseudo signal is supported. It is determined whether the value is within a predetermined range (step S6, “YES” to step S7, “NO”). When bit abnormality detection is completed over the entire bit length (step S7, “YES”), the signal input path switched in step S3 is returned to the sensor detection signal side (SW1 / ON, SW2 / OFF; step). S9), and the process ends (step S10, “END”).

  In the sensor device 2 in which a bit abnormality (bit fixation) is detected, an emergency (such as when a collision occurs) is caused by a bit abnormality (bit fixation) by performing predetermined maintenance (for example, replacement of used parts). Safety and prevention of malfunction during normal operation (during normal operation) (malfunction of occupant protection devices during normal operation) can be achieved.

  That is, after the sensor device 2 is attached to the vehicle 1 by providing the sensor device 2 with the pseudo signal generation unit 12 and the bit abnormality detection means that is performed after the power supplied via the pair of communication lines 100 is provided. Even so, it is possible to detect bit abnormality (bit fixation) of the A / D converter 11 included in the sensor device 2. Since the detection of the bit abnormality is performed over the entire bit length of the register 11b included in the A / D converter 11, the bit abnormality can be detected for each bit of the register 11b. As a result, it is possible to realize the sensor device 2 capable of detecting a bit abnormality having a value corresponding to a region in the vicinity of “−X / + X” that can be determined to have received a collision impact.

  The present invention is not limited to the above-described embodiment, and it goes without saying that various modifications can be made without departing from the gist of the present invention. Next, a modification of this embodiment will be described.

<Modification of First Embodiment>
As a modification of the first embodiment, for example, the pseudo signal generation unit 12 includes a storage memory 12a in which predetermined data is written in advance. This storage memory is provided by a communication control circuit included in the slave communication device 9. The storage area may be shared. The analog signal input switch (SW1, SW2) to the A / D converter 11 may be a general-purpose switch such as SPDT. Similarly, data written in the storage memory 12a in advance may be exchanged between the devices after the communication relationship between the ECU device 2 and the sensor device 3 is established. In addition, after the bit abnormality detection procedure for the acquired A / D conversion value is included on the sensor device 2 side, the detection result (abnormality shown in step S8) shown in FIG. Only detection) may be notified. Any modification can achieve the same effect as the first embodiment, and can be expected to contribute to size reduction, cost reduction, and space saving.

<Second embodiment>
Next, a second embodiment of the present invention will be described in detail with reference to the drawings shown in FIGS. In addition, in the code | symbol shown in FIG.3 (b), the structure to which the code | symbol same as FIG.1 (b) is attached | subjected is a common structure, and it focuses on the structure which attached | subjected the code | symbol different in the following description. Explained.

  FIG. 3B is a schematic configuration diagram illustrating a one-to-one connection form between the ECU device 3 and the sensor device 2 including the pseudo signal generation unit 12 in the second embodiment. FIG. 5 shows a flowchart of the bit abnormality detection means in this embodiment.

  In the present embodiment, as shown in FIG. 3B, the pseudo signal generator 12 includes a storage memory 12c in which predetermined digital data (inspection value) is written in advance and a switch (SW1, SW2). The first embodiment generates and applies an analog signal (voltage value) corresponding to each bit amount of the A / D converter 11 as a pseudo signal, whereas the second embodiment is written in advance in the storage memory 12c. The difference is that the input digital data (predetermined inspection value) is directly input to the register 11b (A / D register) (without passing through the sample hold 11a). Here, the storage memory 12c functions as test value generation means for generating a predetermined digital value similar to that stored in the A / D register as a test value, and switches (SW1, SW2). Functions as switching means for switching the input path to the A / D converter 11 between the output signal of the acceleration detection sensor 21 and the inspection value written in advance in the storage memory 12c.

  Therefore, since digital data is directly input to the input side of the register 11b provided in the A / D converter 11, further improvement in inspection accuracy, miniaturization, and cost reduction are achieved without increasing the circuit scale. There are advantages.

  The storage memory 12c is composed of a general-purpose storage memory such as EPROM, for example, and the digital data stored in advance stores data in a complementary relationship corresponding to the entire bit length of the A / D converter 11. . As an example of a 10-bit long test value, “(MSB) 10101010101 (LSB): 155h” as a first fixed value and “(MSB) 01010101010 (LSB): 2AAh” as a second fixed value in a complement relation Will be written.

  Next, the bit abnormality detection means using the pseudo signal generation unit 12 of this embodiment will be described according to the flowchart shown in FIG. Since the present embodiment and the first embodiment have the same relationship regarding the power feeding phase and the communication phase between the ECU device 3 and the sensor device 2, the procedure from step 1 to step 3 is the same as that of the first embodiment. It is.

  By the processing shown in step 3, the input path to the A / D converter 11 is switched between the output signal of the acceleration detection sensor 21 and the inspection value written in advance in the storage memory 12c, and then stored in the storage memory in advance. The digital value (inspection value) written in 12c is output to the register 11b which is an A / D register of the A / D converter 11 (step 11). The register 11b stores and holds the output data and outputs it to the slave communication device 9 at a predetermined timing. The slave communicator 9 transmits the digital data output from the register 11b to the ECU device 3 (step 12), and the data output from the register 11b matches the data of the inspection value previously written in the storage memory 12c. Whether or not (step S13).

  In step S13, if the data does not match (step S13, “NO”), it is determined that a bit abnormality (bit fixation) has been detected, and it is determined that the product of the A / D converter 11 is defective (step S8, “NO”). Anomaly detection ”).

  The determination shown in step S13 is executed again using the 10-bit test value which is the second fixed value in the complement relation (step S13, “YES” to step S14, “NO”). As described above, when the bit abnormality detection is completed by the first fixed value and the second fixed value that are in the complement relationship with each other (step S14, “YES”), the signal input path switched in step S3 is detected by the sensor. It returns to the detection signal side (SW1 / ON, SW2 / OFF; step S9) and ends (step S10, “END”).

  As shown in the present embodiment, it is possible to detect a bit abnormality (bit fixation) in the register 11b provided in the A / D converter 11 without using an analog signal. Similarly to the first embodiment, the sensor device 2 in which the bit abnormality (bit fixation) is detected causes the bit abnormality (bit fixation) by performing maintenance (for example, replacement of used parts). It is possible to achieve safety in emergency situations (such as when a collision occurs) and prevent malfunctions during normal operation (during normal operation) (malfunctions of occupant protection devices during normal operation).

  The present invention is not limited to the above-described embodiment, and it goes without saying that various modifications can be made without departing from the gist of the present invention. Next, a modification of this embodiment will be described.

<Modification of Second Embodiment>
As a modification of the second embodiment, for example, the pseudo signal generation unit 12 includes a storage memory 12c in which predetermined data is written in advance. This storage memory is provided by a communication control circuit included in the slave communication device 9. The storage area may be shared. In this case, since the timing for reading the inspection value can be estimated, for example, it is possible to omit the switch of SW2. Similarly, data written in advance in the storage memory 12c may be exchanged between the devices after the communication relationship between the ECU device 2 / sensor device 3 is established. In addition, after the bit abnormality detection procedure for the acquired A / D conversion value (register 12b output value) is included on the sensor device 2 side, the detection result (shown in FIG. It is also possible to notify only the abnormality detection shown in step S8. Any modification can achieve the same effect as the second embodiment, and can be expected to contribute to miniaturization, cost reduction, and space saving.

FIG. 1A is an arrangement schematic diagram of a sensor device equipped with an acceleration detection sensor as a sensor device of the present invention when mounted on a vehicle, and is a top view in which the upper side is the front of the vehicle. FIG. 1B is a schematic configuration diagram showing a simple one-to-one connection form between the ECU device 3 and the sensor device 2. FIG. 2A is a schematic diagram of power supply and mutual communication by the differential method between the main communication device 8 and the slave communication device 9, and the slave communication device 9 connection with the voltage value on the vertical axis and the time on the horizontal axis. It is a graph of a potential waveform generated between terminals (9a, 9b). FIG. 2B is a graph showing the relationship between the acceleration amount (G) detected by the acceleration detection sensor 21 and the voltage value (analog signal) as a sensor output signal. FIG. 3A is a schematic configuration diagram illustrating a one-to-one connection form between the ECU device 3 and the sensor device 2 including the pseudo signal generation unit 12 in the first embodiment. FIG. 3B is a schematic configuration diagram illustrating a one-to-one connection form between the ECU device 3 and the sensor device 2 including the pseudo signal generation unit 12 according to the second embodiment. FIG. 4 is a flowchart of the bit abnormality detection means in the first embodiment. FIG. 5 is a flowchart of the bit abnormality detection means in the second embodiment.

Explanation of symbols

1: vehicle, 2, 2a-2f: sensor device, 3: ECU device,
4, 5: Airbag device, 6a, b: Curtain airbag device, 7a-7d: Seat belt pre-tensioner device,
8: master communication device, 8a, b: connection terminal, 9: slave communication device, 9a, b: connection terminal,
10: power supply circuit, 11: A / D converter, 11a: sample hold, 11b: register,
12: pseudo signal generation unit, 12a, c: storage memory, 12b: D / A converter,
21: Acceleration detection sensor 100, 100a to 100f: connection wiring,
SW1, SW2: Switcher

Claims (7)

A slave communicator connected to a main communicator provided in the ECU device via a pair of communication lines and capable of mutual communication and power supply; a sensor for detecting a predetermined physical quantity and outputting an electrical signal in analog; An A / D converter for A / D converting the output signal of the sensor and storing the converted digital value in an A / D register, and the digital value stored in the A / D register is converted into the slave communication device. A sensor device configured to transmit to the ECU device via the pair of communication lines,
Pseudo signal generation means for generating a signal similar to that output by the sensor as a pseudo signal;
Switching means for switching the input to the A / D converter between the output signal of the sensor and the pseudo signal of the pseudo signal generating means;
The pseudo signal of the pseudo signal generating means is input to the A / D converter through switching by the switching means, and a digital value after A / D conversion is read from the A / D register, and the pseudo signal is converted into the pseudo signal. A bit abnormality detecting means for detecting a bit abnormality of the A / D register by determining whether or not the value is within a corresponding predetermined range;
A sensor device. The pseudo signal generation means generates the pseudo signal while sequentially changing the voltage level within a predetermined range,
The abnormality detecting means sequentially reads out the digital value after A / D conversion based on the pseudo signal input from the pseudo signal generating means from the A / D register, and a value within a predetermined range corresponding to each pseudo signal Whether or not
The sensor device according to claim 1. A slave communicator connected to a main communicator provided in the ECU device via a pair of communication lines and capable of mutual communication and power supply; a sensor for detecting a predetermined physical quantity and outputting an electrical signal in analog; An A / D converter for A / D converting the output signal of the sensor and storing the converted digital value in an A / D register, and the digital value stored in the A / D register is converted into the slave communication device. A sensor device configured to transmit to the ECU device via the pair of communication lines,
Test value generating means for generating a predetermined digital value corresponding to the output bit length of the A / D register as a test value;
Switching means for switching the input to the A / D converter between the output signal of the sensor and the inspection value of the inspection value generating means;
By writing the inspection value of the inspection value generation means to the A / D register through switching by the switching means, and reading out a digital value from the A / D register to determine a match with the inspection value. Bit abnormality detection means for detecting a bit abnormality of the A / D register,
A sensor device. The inspection value includes a first fixed value corresponding to the output bit length of the A / D register and a second fixed value in a complement relation of the first fixed value.
The sensor device according to claim 3. The driving power source of the sensor is generated based on the power supplied via the slave communication device.
The sensor device according to any one of claims 1 to 4, wherein In the initialization process after power is turned on via the pair of communication lines, bit abnormality detection of the A / D register is performed by the abnormality detection means.
The sensor device according to any one of claims 1 to 5, wherein It is mounted on a vehicle together with the ECU device,
The sensor is configured by any one of an acceleration detection sensor or a pressure detection sensor, an ultrasonic sensor, an acoustic sensor, or an optical fiber sensor.
The sensor device according to any one of claims 1 to 6, wherein

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