JP4839699B2 - Vehicle sensor control system - Google Patents

Description

  The present invention relates to a vehicle sensor control system connected to at least one sensor via a bus.

2. Description of the Related Art Conventionally, there is an automobile control system in which a detection value detected by an in-vehicle analog sensor is transmitted as an analog signal on a data bus and converted into a digital signal by an A / D converter in a control device connected to the bus Are known. (For example, refer to Patent Document 1). The control device of the vehicle control system executes predetermined vehicle control based on the detected value of the analog sensor converted into the digital signal.
Japanese Patent Laid-Open No. 11-27300

  By the way, in recent years, as the number of sensors mounted on vehicles increases, the number of wirings increases, the number of connector pins of the control ECU increases so that more sensor information can be captured, or the number of control ECUs themselves that capture sensor information. Has increased. In order to cope with such an increasing tendency, a control ECU that takes in each sensor and its sensor information is often connected by a bus using a communication protocol such as CAN.

  However, when an advanced communication protocol such as CAN is used, it is necessary to install a dedicated communication controller or a dedicated communication driver IC corresponding to such a communication protocol for each sensor as well as the control ECU. It was one of the causes of system complexity.

  In this regard, the above-described conventional technique is configured to collect all the detection signals of a plurality of sensors in a multiplex communication circuit and then transmit the collected signals to the control ECU. However, the plurality of sensors are arranged in a distributed manner in the vehicle. In some cases, by consolidating the wirings connected from each sensor to the multiplex communication circuit, the wiring becomes complicated and the number of wirings increases.

  Therefore, an object of the present invention is to provide a vehicle sensor control system that can acquire data transmitted from each of at least one or more sensors connected to a bus with a simple configuration.

In order to solve the above problems, according to one aspect of the present invention,
A vehicle sensor control system having at least one or more in-vehicle sensors that perform state detection and a control unit that receives data from each of the sensors,
The control unit transmits information defining data transmission timing of each sensor on a bus connected to each sensor, and each sensor transmits digital data in a detected state to the control unit according to the information. A vehicle sensor control system is provided.

  Thus, each sensor only needs to transmit data in accordance with information defining the data transmission timing, and the control unit can easily recognize which sensor is the received data.

  Further, in order for each sensor to grasp its own data transmission timing, it is desirable that the information defining the data transmission timing of each sensor is a synchronization pulse having at least two pulse portions having different periods. Each sensor can transmit data at a predetermined transmission timing, starting from the pulse part whose period has changed.

  Further, by sharing the bus for transmitting information defining the data transmission timing of each sensor with the power supply bus for each sensor, the line can be saved. At this time, the control unit preferably supplies a pulsed voltage as a power supply voltage for each sensor, or supplies a pulsed current as a power supply current for each sensor. Thereby, even if it carries out a wire saving, it becomes possible to synchronize each sensor and a control part, ensuring the power supply required for each sensor.

  Further, when the frequency of the synchronization pulse transmitted by the control unit is made variable, the output cycle of each sensor can be made variable.

  Moreover, it is preferable that the said vehicle-mounted sensor transmits the digital data of the reference voltage which divided | segmented the power supply voltage at the time of A / D-converting the detected state to the said control part. Thereby, the control unit side can also correct the detected digital data based on the acquired digital data of the power supply voltage by acquiring the power supply voltage when each sensor performs A / D conversion. become.

  Moreover, it is also preferable that the on-vehicle sensor transmits digital data obtained by A / D converting the difference between the previous value and the current value of the detected analog data. Thereby, resolution | decomposability goes up and the precision of the transmission data which a sensor transmits can be improved.

  According to the present invention, data transmitted from each of at least one sensor connected to the bus can be acquired with a simple configuration.

  The best mode for carrying out the present invention will be described below with reference to the drawings. FIG. 1 is an example diagram showing an embodiment of a vehicle sensor control system of the present invention. The in-vehicle sensor A and the in-vehicle sensor B detect the state of the vehicle, and are connected to the sensor control unit 10 via the three buses 20a, 20b, and 20c. The sensor control unit 10 receives data transmitted by the sensor A and the sensor B. The sensor control unit 10 temporarily stores data received from each sensor, and performs predetermined control based on the data. For example, the sensor control unit 10 transmits a control signal calculated based on data received from each sensor on a bus 20d connected to the other control device periodically or in response to a request from the other control device. . For convenience of explanation, the number of sensors in this embodiment is two, but there may be more than that.

  Information defining the timing at which the sensors A and B transmit data is transmitted to the bus 20a, and digital data detected by the sensors A and B is transmitted to the bus 20b. The bus 20c is a line that shares the GND of the sensor control unit 10 with the GND of the sensors A and B. The sensor control unit 10 transmits the information defining the data transmission timing on the bus 20a connected to the sensors A and B, and each of the sensors A and B defines the data transmission timing of the detected digital data. It transmits to the sensor control part 10 according to the information to perform.

  The data transmission timing defining information transmitted by the sensor control unit 10 includes a synchronization pulse (synchronization clock). For example, each sensor transmits digital data to the sensor control unit 10 at a predetermined edge for each sensor on the synchronization pulse. The data transmission timing defining information transmitted by the sensor control unit 10 may be ID information. Each sensor transmits digital data to the sensor control unit 10 when receiving the same ID information as the ID information given to the sensor.

  FIG. 5 is a schematic configuration diagram in each sensor. Each sensor generally includes a sensor element 36, an intelligent general-purpose IC 30 (hereinafter referred to as “IC30”), and a power supply circuit 37.

  The power supply circuit 37 regulates a power supply voltage supplied from the outside. The voltage regulated by the power supply circuit 37 is supplied to the IC 30 or the like in the sensor as a power supply voltage. The sensor element 36 is a part that detects a physical quantity. For example, a semiconductor element whose electrical resistance changes according to temperature, a strain gauge that detects a pressure change, and a magnet coil that measures the number of rotations of a rotating body can be used. The analog value detected by the sensor element 36 is input to the IC 30 and converted into a digital value by the A / D converter 34. The converted digital value is set in the register 35. The counter processing unit 33 monitors data transmission timing defining information transmitted from the sensor control unit 10 via the bus 20a. For example, the counter processing unit 33 counts the synchronous clock. The output circuit 32 transmits the value in the register 35 to the bus 20b at a predetermined transmission timing based on the count result by the counter processing unit 33.

  FIG. 2 is a first example showing the relationship between the synchronous clock that transmits the bus 20a and the digital data of the sensor output that transmits the bus 20b. The sensor control unit 10 transmits a synchronous clock defining data transmission timing on the bus 20a as shown in FIG. The synchronous clock shown in FIG. 2A has a missing tooth (missing portion) between the pulse 2 and the pulse 3. The sensor control unit 10 transmits a synchronous clock in which missing teeth appear at a predetermined cycle on the bus 20a.

  Sensor A is preset to transmit digital data on the falling edge of the first pulse after the missing tooth, and sensor B receives the digital data on the falling edge of the sixth pulse after the missing tooth. It is preset to transmit. By making such an arrangement between each sensor and the sensor control unit 10 in advance, the sensor control unit 10 can recognize which sensor is the received data.

  In addition to FIG. 2, synchronization can be achieved as shown in FIG. FIG. 3 is a second example showing the relationship between the synchronous clock that transmits the bus 20a and the digital data of the sensor output that transmits the bus 20b. The sensor control unit 10 transmits a synchronous clock defining data transmission timing on the bus 20a as shown in FIG. The synchronous clock shown in FIG. 3A has two pulse parts with different periods. In the example of FIG. 3A, a pulse portion (portion composed of pulses 3, 4, and 5) having a longer period than the other pulse portions is included. The sensor control unit 10 transmits, on the bus 20a, a synchronous clock in which a pulse part having a different period from other pulse parts appears at a predetermined period. The counter processing unit 33 in each sensor monitors the synchronous clock including the change of the cycle.

  Sensor A is preset to transmit digital data at the falling edge of the first pulse after 3 pulses of the different period pulse part, and sensor B is the sixth pulse after 3 pulses of the different frequency pulse part. It is preset that digital data is transmitted at the falling edge. By making such an arrangement between each sensor and the sensor control unit 10 in advance, the sensor control unit 10 can recognize which sensor is the received data.

  By the way, if the data output order of each sensor can be variably set, the expandability such as the ability to reset the output order once set becomes high. Therefore, each sensor is preferably provided with an ID setting unit 31. The number of digital data transmitted from the missing tooth is determined by the ID setting. The ID setting unit 31 determines the output order according to the input setting from the outside of the sensor.

  For example, the ID setting unit 31 determines the output order according to the input voltage determined by adjusting the resistance value with the adjustment resistor. That is, the input voltage divided by the adjustment resistor is input to the ID setting unit 31, and the output order is determined based on a predetermined correspondence between the input voltage and the output order. For example, a sensor in which the input voltage to the ID setting unit 31 is set to 1V is associated with transmitting digital data at the falling edge of the first pulse from the missing tooth, and the input voltage to the ID setting unit 31 is 4V. The set sensor is associated with transmitting digital data at the falling edge of the sixth pulse from the missing tooth. Note that the 256 output orders can be changed by A / D converting the input voltage value with, for example, 8-bit resolution. It is also possible to determine the output order based on the combination of Lo / Hi voltages input by pulling up or pulling down some general purpose ports of the IC 30.

  In addition to making the output order of the data of each sensor variable, it may be desirable for control if the output cycle of each sensor can be made variable. For example, for control purposes, the data of sensor A needs to be captured at a fast cycle, while the data of sensor B may be captured at a slow cycle. FIG. 6 is an example of a diagram illustrating a mode in which the data output period of each sensor is variable.

  Sensor A is preset to transmit digital data on the falling edge of the first pulse after the missing tooth, and sensor B receives the digital data on the falling edge of the sixth pulse after the missing tooth. It is preset to transmit. And the sensor control part 10 transmits the synchronous pulse which a missing tooth appears at arbitrary timings on the bus | bath 20a. Thereby, if the sensor control unit 10 generates a missing tooth at an arbitrary timing, a sensor preset to transmit digital data at the falling edge of the first pulse after the missing tooth inevitably. A data is output. In other words, a sensor with a high priority, such as wanting to speed up the output cycle, may be set to transmit digital data at the edge of a pulse that is as close as possible after the missing tooth.

  Alternatively, the output cycle of each sensor can be made variable by making the frequency of the synchronization pulse transmitted by the sensor control unit 10 variable. For example, if the sensor A is preset to transmit digital data at the falling edge of the first pulse after the missing tooth, the output period of the sensor A is increased by increasing the frequency of the synchronization pulse. can do. Increasing the frequency of the sync pulse also contributes to shortening the time of the initial check of each sensor that is performed when the vehicle sensor control system is started up.

  The sensor controller 10 may change the dynamic range of the sensor element 36 in the sensor by changing the frequency of the synchronization pulse. That is, the dynamic range is determined based on a predetermined correspondence between the frequency of the synchronization pulse and the dynamic range of the sensor element 36. For example, when the sensor control unit 10 requests highly accurate data, a synchronization pulse having a predetermined frequency representing the request is transmitted to the bus 20a, and the sensor side receiving the request transmits the amplification factor of the A / D first stage. Or the double precision data is transmitted to the sensor control unit 10.

  By the way, as a fail-safe of the vehicle sensor control system, the sensor control unit 10 performs control to periodically stop and check the function of each sensor. Now, it is assumed that the sensors A, B, and C are preset to transmit digital data at the falling edges of the first, fourth, and seventh pulses after the missing teeth, respectively. The sensor control unit 10 transmits synchronization pulses up to the second pulse after the missing tooth so that only the sensor A is transmitted as digital data. If the check of the received data of the sensor A is normal, the sensor control unit 10 then synchronizes pulses up to the fifth pulse after the missing tooth so that the transmission of the digital data is up to the sensor B. (At this time, the sensors A and B transmit data). If the check of the received sensor B data is normal, the sensor control unit 10 then synchronizes pulses up to the eighth pulse after the missing tooth so that the transmission of the digital data is up to the sensor C. (At this time, the sensors A, B, and C transmit data). By repeating such a process, it is possible to check all the sensors connected to the bus, and it is possible to check one sensor by eliminating the influence of other sensors connected to the bus. become able to.

  In the sense of fail-safe in the above-described vehicle sensor control system, the number of buses for transmitting digital data is not limited to one, but two buses 20e and 20f may be used as shown in FIG. If the wiring is made redundant in this way, transmission / reception can be continued with the remaining one even if one becomes unable to transmit / receive due to disconnection or short circuit. The GND line may be connected to the sensor control unit 10 as in the above example, or may be connected to a groundable position near the mounting of each sensor.

  Further, as shown in FIG. 8, mirror data may be transmitted. That is, by transmitting the digital data to the data bus 20e and the mirror data to the data bus 20f, it is possible to prevent the influence of common mode noise and the like and improve the communication reliability.

  By the way, it is possible to reduce the number of lines by sharing the bus 20a for transmitting the synchronous clock with the power supply bus for each sensor. FIG. 4 shows an example of a pulse waveform on a bus in which a power supply bus and a synchronous clock transmission bus 20a are shared. FIG. 4A shows a synchronization pulse in which the power supply voltage transmitted by the sensor control unit 10 is controlled in a pulse shape. That is, a pulse voltage is supplied as a power supply voltage for each sensor. In the case of FIG. 4A, a voltage control circuit (for example, a switching power supply circuit or a series power supply circuit) is provided in the sensor control unit 10, and the voltage control circuit is 5V-12V as shown in FIG. The pulse waveform is output as a synchronous clock. On the other hand, FIG. 4B is a synchronization pulse in which the power supply current transmitted by the sensor control unit 10 is controlled in a pulse shape. That is, a pulsed current is supplied as a power supply current for each sensor. In the case of FIG. 4B, a constant current control circuit is provided in the sensor control unit 10, and the constant current control circuit outputs a 5 mA-10 mA pulse waveform as shown in FIG. 4B to the bus 20a as a synchronous clock. In addition, both the synchronous clock by these power supply voltages and the synchronous clock by a power supply current have a missing-tooth part or a pulse part of a different period similarly to the above-mentioned.

  On the other hand, the counter processing unit 33 on the sensor side counts the synchronous clock by the power supply voltage or the synchronous clock by the power supply current in the same manner as the synchronous clock when the line saving is not performed. Then, the output circuit 32 transmits the value in the register 35 to the bus 20b at a predetermined transmission timing based on the count result by the counter processing unit 33.

  As a result, even if the above-described line saving is performed, each sensor and the sensor control unit 10 can be synchronized while securing the power supply necessary for the sensor. The power supply circuit 37 regulates the power supply voltage supplied from the bus 20a so that the conversion value in the A / D conversion section 34 in the sensor does not fluctuate due to fluctuations in the power supply voltage, and the A / D conversion section 34. It is necessary to supply to IC30 which has. Moreover, it is necessary that the effective value of the pulsed power supply voltage supplied to each sensor does not fall below the minimum operating voltage required for normal operation of each sensor.

  By the way, in a sensor having no voltage ratio, the A / D conversion value also changes due to the fluctuation of the power supply voltage supplied to the A / D converter 34, and therefore the accuracy of the power supply voltage regulated by the power supply circuit 37 is poor. And the conversion accuracy will be worse. Therefore, each sensor monitors a reference voltage obtained by dividing the power supply voltage with a resistor or the like in order to monitor the power supply voltage when A / D converting the state detected by itself. Then, the digital data obtained by converting the reference voltage by the A / D conversion unit 34 is transmitted to the sensor control unit 10. As a result, the sensor control unit 10 cannot recognize the A / D conversion accuracy of the digital data only by receiving only the digital data detected by each sensor, but when each sensor performs A / D conversion. By acquiring the power supply voltage, it is possible to correct the detected digital data based on the acquired digital data of the power supply voltage.

  In addition, the sensor output value is not the analog data detected in a predetermined detection cycle, A / D-converted into digital data as it is, but is sent between the previous value and the current value of the detected analog data. You may make it transmit the digital data which A / D converted the difference. Thereby, resolution | decomposability goes up and the precision of the transmission data which a sensor transmits can be improved. For example, when the value transmitted last time is 3V and the value transmitted this time is 3.1V, the sensor transmits digital data obtained by A / D converting 0.1 V of the difference.

  Further, only the lower bits of the A / D converted digital data are transmitted in a predetermined transmission cycle, and the upper bits of the A / D converted digital data are transmitted in a transmission cycle longer than the predetermined transmission cycle. Good. Thereby, the sensor control unit 10 can acquire data that requires accuracy while limiting the amount of transmission data.

  The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above-described embodiments, and various modifications and substitutions can be made to the above-described embodiments without departing from the scope of the present invention. Can be added.

  For example, as shown in FIG. 9, a bus 20a in which a bus transmitted by a synchronous clock is shared with a power supply bus for each sensor, and ID information given to each sensor transmitted by the sensor control unit 10 is transmitted. A vehicle sensor control system having a bus 20g, a bus 20b that transmits digital data detected by the sensors A and B, and a bus 20c that shares the GND of the sensor control unit 10 and the GND of the sensors A and B. Can be mentioned.

  The sensor control unit 10 transmits ID information on the bus 20g, and each sensor always monitors the ID information on the bus 20g. Each sensor transmits the digital data detected only when it coincides with its own ID information to the sensor control unit 10 on the bus 20b. Thus, the sensor control unit 10 can acquire digital data in a state detected by a specific sensor by specifying an ID when necessary. As a result, the load on the bus can be reduced, and as many sensors as physically possible can be connected.

It is an example figure which shows one form of the sensor control system for vehicles of this invention. It is a 1st example figure showing the relationship between the synchronous clock which transmits the bus | bath 20a, and the digital data of the sensor output which transmits the bus | bath 20b. It is the 2nd example figure showing the relation between the synchronous clock which transmits bus 20a, and the digital data of the sensor output which transmits bus 20b. It is an example of a pulse waveform on a bus in which a power supply bus and a synchronous clock transmission bus 20a are shared. It is a schematic block diagram in each sensor. It is an example of the figure which shows the aspect which makes the output cycle of the data of each sensor variable. It is a 2nd example figure which shows one form of the sensor control system for vehicles of this invention. It is a figure which shows the digital data which transmit the data buses 20e and 20f. It is a 3rd example figure which shows one form of the sensor control system for vehicles of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Sensor control part 20 Data bus 20a, e, f Transmission clock of synchronous clock 20b Transmission bus of digital data transmitted by sensor 20c Ground line 20d Bus connected to other control devices 20g Bus transmitting ID information 30 Intelligent general purpose IC

Claims (8)

Have a control unit for receiving data from at least one vehicle sensor and each sensor thereof detecting the state,
The control unit transmits a synchronization pulse that defines a data transmission timing of each sensor on a bus connected to each sensor, and each sensor transmits the detected digital data to the control unit according to the synchronization pulse. A vehicle sensor control system for transmitting ,
The vehicle sensor control system , wherein the control unit makes the output cycle of each sensor variable by changing the frequency of the synchronization pulse . The vehicle sensor control system according to claim 1, wherein the control unit makes the output cycle of each sensor variable according to a timing at which a missing tooth is generated in the synchronization pulse. 3. The vehicle sensor control system according to claim 1, wherein the control unit makes the output cycle of each sensor variable by changing the number of pulses after missing teeth of the synchronization pulse. 4. 3. The vehicle sensor control system according to claim 1, wherein the control unit increases the number of sensors that transmit digital data by increasing the number of pulses after missing the synchronization pulse. 4. The control unit limits the number of pulses after missing teeth of the synchronization pulse so that digital data is not transmitted from the first sensor and digital data is not transmitted from the second sensor, and the received first sensor The number of pulses after missing teeth of the synchronization pulse is increased so that digital data is transmitted from the first sensor and the second sensor when the digital data is normal. Vehicle sensor control system. The vehicle sensor control system according to claim 1, wherein the control unit changes a dynamic range of each sensor by changing a frequency of the synchronization pulse. The said control part correct | amends the digital data of the state which each said sensor detected by acquiring the digital data of the power supply voltage of each said sensor from each said sensor. Vehicle sensor control system. The vehicle sensor control system according to any one of claims 1 to 7, wherein each sensor transmits upper bits of A / D converted digital data in a transmission cycle longer than a transmission cycle of lower bits.

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