WO2006001264A1

WO2006001264A1 - Occupant detection apparatus for vehicle

Info

Publication number: WO2006001264A1
Application number: PCT/JP2005/011316
Authority: WO
Inventors: Morio Sakai; Masaki Mori; Chiaki Sumi
Original assignee: Aisin Seiki Kabushiki Kaisha
Priority date: 2004-06-28
Filing date: 2005-06-21
Publication date: 2006-01-05
Also published as: JP2006010581A

Abstract

An occupant detection apparatus for a vehicle, capable of accurately detecting load on a vehicle seat to detect an occupant on the seat without impairing anti-noise capability. An occupant detection apparatus for a vehicle, having a load detection device (2) for detecting load on a vehicle seat and a control device (1) for recognizing an occupant based on load data inputted from the load detection device (2). The load detection device (2) has a measurement section (3) for measuring load and a storage section (5) for storing a measurement standard value defining the standard of measurement by the measurement section (3). The storage section (5) has storage means which is rewritable and non-volatile.

Description

Specification

Vehicle occupant detection device

Technical field

The present invention relates to a vehicle occupant detection device that detects a load on a vehicle seat and discriminates an occupant on the vehicle seat based on the detected load data.

Background art

[0002] As an apparatus as described above, for example, in Patent Document 1 shown below, a vehicle occupant detection apparatus that can determine and adjust a value after a load sensor is assembled to a vehicle seat is disclosed. Is disclosed. This load detection device includes at least one threshold value storage means for storing a determination threshold value for determining the state of a vehicle occupant based on a load measurement result from a load sensor that detects a load on a vehicle seat. Have one. At least a part of the threshold value storage means is constituted by a rewritable nonvolatile memory. Then, the determination threshold value can be easily and reliably adjusted by rewriting the contents of the nonvolatile memory by communication with external force using a calibration inspection tool or the like. As a result, the value can be adjusted after the load sensor is attached to the vehicle seat or after the vehicle seat with the load sensor is attached to the vehicle. Further, it is disclosed that this determination threshold value is an occupant determination threshold value for determining the type of a vehicle occupant or a zero point load threshold value indicating a load when a vehicle seat is empty. In Patent Documents 2 and 3 shown below, a technique for measuring a signal output from a load sensor and calibrating (calibrating) the signal output in a situation in which a passenger can be determined to be sitting and sitting as zero value. Is disclosed.

Patent Document 1: JP 2004-125595 A (Page 3-4)

Patent Document 2: JP 2000-283834 A (paragraphs 0019 to 0020)

Patent Document 3: Japanese Patent Laid-Open No. 2001-21411 (paragraphs 0072-0073)

Disclosure of the invention

Problems to be solved by the invention

[0003] However, in the techniques disclosed in Patent Documents 1 to 3, the output value of the load sensor The controller applies the correction. Specifically, for example, it is assumed that the output range force of the load sensor is 0 to LOO, and the value of the load sensor is 20 in a vacant seat state after the vehicle seat with the load sensor is attached to the vehicle. If so, the technique described in Patent Document 1 corrects the threshold value so that it is regarded as a zero point. As a result, the output range from 0 to 100 becomes 20: LOO, and the measurement range becomes narrow.

[0004] To cope with this problem, for example, it is possible to secure 100 output domains even after correction. In other words, if a method such as setting the output of the load sensor itself to 0 to 120 is adopted, 100 output ranges can be secured even after correction as described above. However, if the detection range of the load sensor is expanded to a part that can be discarded due to correction, the measurement system of the load sensor, that is, the resolution, deteriorates. That is, for example, when the output voltage range of 6 V (volts) is set to an output range of 0 to 100, the output changes by 1 with respect to the output voltage of 6 mV. When the output range is 0 to 120, the output changes 1 for 5mV. The output voltage of 6mV is more tolerant when noise or other contamination is assumed. In recent years, there are many noise sources such as navigation systems, ETC (automatic toll collection system) cabin units, and audio equipment. Therefore, improving noise resistance from various viewpoints is indispensable for building a stable vehicle system, and the techniques described in Patent Documents 1 to 3 are not sufficient.

[0005] In view of the above problems, an object of the present invention is to provide a vehicle occupant detection device capable of detecting a load on a vehicle seat with high accuracy without impairing noise resistance and detecting an occupant on the vehicle seat. And

Means for solving the problem

[0006] A characteristic configuration of a vehicle occupant detection device according to the present invention for achieving this object is based on a load detection device that detects a load on a vehicle seat and load data input from the load detection device. The load detection device includes a measurement unit that measures the load and a storage unit that stores a measurement reference value that determines a measurement reference by the measurement unit. And the storage unit includes a rewritable and nonvolatile storage unit.

[0007] According to this characteristic configuration, for example, the control device is used to determine an occupant. The storage unit provided in the load detection device that detects the load of the vehicle seat that does not store the value and inputs the load data to the control device has a rewritable and non-volatile storage means. Configured. The storage unit stores a measurement reference value that defines a measurement reference by a measurement unit included in the load detection device, for example, a strain gauge that measures a load. Therefore, when the load data input to the control device deviates from the design value or when assembling the product, so-called deviation occurs, the load data is used to determine the occupant in the control device, and the value is corrected. I need to do it. This deviation can be improved by correcting the measurement reference value inside the load detector that generates load data. In addition, in order to improve the deviation on the load detection device side, all the input load data can be used as valid data on the control device side. Therefore, the effective data range is not unintentionally narrowed on the control device side. In addition, in view of the narrowing of the effective data range from the load detection device side, it is no longer necessary to output load data including unnecessary portions. Therefore, the load detection device can output the load data in the range of the effective data, maintain the accuracy of the load data, and enhance the noise resistance.

[0008] Further, in the above configuration, the measurement reference value is a value that determines an output of the load detection device in a no-load state in which no occupant is present on the vehicle seat.

[0009] According to this characteristic configuration, the value that determines the output of the load detection device in a no-load state in which no occupant is present on the vehicle seat, that is, the output at the so-called zero point, is used as the measurement reference value. Therefore, it is possible to check the deviation of the load data without going through a special adjustment process, such as placing an adjustment weight on the vehicle seat.

[0010] Further, the measurement reference value may be configured to be a value that defines a range that needs to be transmitted to the control device among loads measurable by the measurement unit.

[0011] According to this configuration, for example, a value that determines a range that needs to be transmitted as load data from the load detection device to the control device among the loads that can be measured by a measurement unit including a strain gauge or the like is measured It is said. Therefore, even when the deviation of the load data is confirmed, the measurement reference value can be updated while maintaining the range, that is, the effective data width. wear. As a result, it is not necessary to output load data from the load detection device side including the unnecessary portion in anticipation of correction of deviation in the control device. Therefore, the load detection device can output the load data in the range of the valid data, and can maintain the accuracy of the load data.

[0012] Further, in the above configuration, it is preferable that the load detection device executes a measurement reference value update process and updates the measurement reference value according to an instruction from the control device.

[0013] According to this, in accordance with an instruction from the control device, the load detection device executes a measurement reference value update process and updates the measurement reference value. Therefore, for example, deviation can be corrected without connecting an inspection machine or the like. Even when an inspection machine is connected to perform adjustment and inspection, execution programs such as measurement reference value update instructions and measurement reference value update processing are stored in the control device and load detection device in the vehicle. Yes. Therefore, the inspection machine only needs to give a trigger for starting the execution program, and it is not necessary to prepare an inspection machine corresponding to each vehicle type.

[0014] Further, it is preferable that the load detection device and the control device can perform bidirectional communication. If bidirectional communication is possible, the control unit can perform control such as setting and correction of the signal processing circuit included in the load detection device that only receives load data from the load detection device.

[0015] Further, it is preferable that the communication speed of the bidirectional communication is variable. If the communication speed is variable, flexible communication control is possible, such as selecting the optimal communication speed according to the urgency of communication and the amount of environmental noise. As an example, when there is a lot of environmental noise, it is possible to reduce the communication speed and ensure reliability.

[0016] In addition, it is preferable that occupant determination information by the control device is transmitted to another control device of the vehicle. A vehicle is provided with many control devices for controlling various devices and actuators, and distributed processing is performed. Therefore, the occupant detection device of the present invention is often a control device that takes on one of many distributed processes. Therefore, if the occupant discrimination information by the control device provided in the occupant detection device of the present invention is transmitted to another control device, this information can be effectively utilized in the transmitted other control device. In other words, suitable vehicle control can be realized by linking the processing results of the distributed processing. Here, it is preferable that the other control device is an airbag control device. According to the occupant detection device of the present invention, the occupant is determined based on the load applied to the vehicle seat. In other words, for example, it is determined whether the occupant is an adult, a child, or a large or small handle depending on the load. It is desirable that the inflation rate of the airbag is controlled according to the physique of the occupant. Therefore, if the occupant discrimination information by the control device of the occupant detection device of the present invention is transmitted to the airbag control device, the inflation degree V and the inflation speed of the airbag can be controlled well.

[0018] Further, it is preferable that the control device is connectable to an inspection machine via an interface. As described above, the inspection machine itself does not need to have an execution program such as a measurement reference value update instruction or measurement reference value update processing. An execution program such as a measurement reference value update command and a measurement reference value update process may be stored in a control device or a load detection device in the vehicle. Then, the load detection device may execute the measurement reference value update process and update the measurement reference value according to an instruction from the controller. However, it is necessary to give a trigger to start these executable programs in some way. It is preferable that this check is performed by an inspection machine that can be connected to the control device via the interface. As a result, the ability to cope with aging changes is improved, and an accurate occupant detection device can be configured.

Here, it is preferable that the inspection machine performs one or both of inspection and calibration of the load detection device. That is, if the inspection machine gives the above-mentioned crack to the control device, the control device can activate one or both of inspection and calibration of the load detection device. As a result, the ability to cope with secular changes is improved, and a highly accurate occupant detection device can be configured.

[0020] Further, it is preferable that the load detecting device is interposed between the vehicle seat and a seat rail installed on the vehicle side. That is, since the load applied to the vehicle seat can be detected well, a highly accurate occupant detection device can be configured.

In addition, it is preferable that the load detection device has a strain sensor. The strain sensor is a load detection sensor that can detect a load with a simple structure and good response. Therefore, if a load detection device is configured with this strain sensor, an accurate occupant detection device can be configured. BEST MODE FOR CARRYING OUT THE INVENTION

[0022] [System overview]

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing the arrangement of each part of a vehicle occupant detection device according to an embodiment of the present invention, and FIG. 2 is a block diagram showing the system configuration of the vehicle occupant detection device according to an embodiment of the present invention. is there.

As shown in FIG. 1, in the present embodiment, a sensor 2 as a load detection device is assembled to the lower part of the vehicle seat 20 so as to measure a load by an occupant seated on the vehicle seat 20. It is configured. The sensors 2 are provided on the seat rail 26 of the vehicle seat 20 as sensors 21 to 24 at four locations, a right front part, a right rear part, a left front part, and a left rear part, respectively. The sensors 21 to 24 are connected to an ECU (Electronic Control Unit) 1 as a control device via a transmission line 25.

In the present embodiment, the sensor 2 is configured using a strain gauge. As shown in FIG. 2, the sensor 2 includes a gauge 3 as a measuring unit and a signal processing unit 4. The signal processing unit 4 includes an analog signal processing unit 12, an analog Z digital conversion unit (hereinafter referred to as AZD conversion unit) 13, a digital signal processing unit 14, and a communication interface unit (hereinafter referred to as communication IZF unit).

15, a signal processing control unit 6 that controls these, and a storage unit ₅ that stores information and data necessary for processing in the signal processing unit 4.

Next, the signal flow of the sensor 2 will be described. The gauge 3 outputs a gauge voltage proportional to the magnitude of strain caused by the weight applied to the vehicle seat 20 (gauge output voltage). The analog signal processing unit 12 includes an amplifier and the like, and the input gage output voltage is amplified here. The amplified signal is then converted into a digital signal by the AZD converter 13. The signal converted into a digital signal is subjected to digital signal processing by the digital signal processing unit 14 such as correcting the signal as necessary or adjusting the format so as to match the communication specifications. . Next, the communication IZF unit 15 performs signal processing such as adding a code for determining a communication error, and outputs the signal to the ECU 1. Since the sensor 2 and the ECU 1 perform bidirectional communication, the communication IZF unit 15 also plays a role of receiving a communication signal input from the ECU 1 and transmitting it to the signal processing control unit 6. The bidirectional communication between ECU1 and sensor2 can be configured to change the communication speed. wear.

[0026] The signal processing control section 6 controls each section of the signal processing section 4. For example, setting or changing the amplification factor of the amplifier included in the analog signal processing unit 12, setting or changing the upper and lower reference voltages of the AZD conversion unit 13, correction or format specification to the digital signal processing unit 14, communication IZF unit Sending instructions to 15 etc. The storage unit 5 is configured to include a nonvolatile memory and the like, and stores values such as an execution program of the signal processing control unit 6 and amplification factors used in the signal processing and upper and lower reference voltages. And These amplification factors, upper and lower reference voltages, etc. function as measurement reference values as described later. The storage unit 5 does not need to be configured using a single nonvolatile memory, for example, an execution program is stored in a ROM that cannot be rewritten, a work area used for digital signal processing is provided in a volatile RAM, and an amplification factor or Values such as the upper and lower limit voltage may be stored in a rewritable flash memory.

[0027] Next, ECU1! The ECU 1 receives the load data output from the sensor 2 via the communication iZF unit 7. As described above, the communication IZF unit 7 also plays a role of transmitting a control command or the like to the signal processing control unit 6 via the communication I ZF unit 15 of the sensor 2. In the present embodiment, since the sensor 2 includes four sensors 21 to 24, the ECU 1 receives four load data. The ECU 1 calculates the total load data by performing calculations such as addition and bias correction on the received load data by the calculation unit 10. The determination unit 11 detects the occupant state on the vehicle seat 20 from the total load data. Here, the detection of the occupant state includes, for example, a vacant seat state, a state where an adult is seated, a state where a child is seated, and the like.

[0028] The detection result in the determination unit 11 is transmitted to other control devices in the vehicle via the communication IZF unit 7. Other control devices in the vehicle are, for example, a seat belt retractor, an ECU that controls an air nog, and the like. In the present embodiment, as shown in FIG. 2, the occupant state on the vehicle seat 20 detected by the airbag EC U30 is transmitted. Based on the detection result at the time of collision, the airbag ECU 30 does not inflate the airbag if it is empty, for example, if it is an adult, it will inflate the airbag to the maximum, and if it is a child, the airbag will inflate Controls such as suppressing or stopping. Note that the ECU 1 is configured to be connectable to the inspection machine 40 via the communication I / F unit 7. The inspection machine 40 is a device for inspecting and calibrating (adjusting) the sensor 2 connected to the ECU 1 in, for example, a store or a repair shop. The program for executing this inspection or calibration need not be installed in the inspection machine 40, but may be stored in the memory means possessed by the ECU 1 or the sensor 2 itself. The inspection machine 40 may be configured to give a start instruction so as to execute a program included in the ECU 1 or the sensor 2, or to display or record an inspection result.

As described above, the vehicle occupant detection device according to the present embodiment is based on the sensor 2 as a load detection device that detects the load on the vehicle seat 20 and the load data input from the sensor 2. It is equipped with ECU1 as a control device for discriminating passengers. The sensor 2 includes a gauge 3 as a measurement unit that measures a load, and a storage unit 5 that stores a measurement reference value that defines a measurement standard by the gauge 3. The storage unit 5 includes rewritable and nonvolatile storage means.

[0031] [Standard operation of system]

Next, an outline of the operation of the vehicle occupant detection apparatus configured as described above will be described. First, the standard operation of ECU1 will be described. FIG. 3 is a flowchart for explaining the standard operation of the ECU of FIG. ECU1 requests sensor 2 to acquire load information (load data) at regular intervals (process # 10) (process # 20). When the sensor 2 (each sensor 21 to 24) also obtains load information (process # 60), the calculation unit 10 calculates the load (process # 70) and determines the occupant on the vehicle seat 20 (process # 60) # 80).

Next, the standard operation of the sensor 2 will be described. FIG. 4 is a flowchart illustrating the standard operation of the sensor of FIG. In response to the sensor load information request from ECU 1 (see process # 20 in FIG. 3), sensor 2 determines whether there is a force with the sensor load information request (process # 30). If the request is helpless, terminate the process and repeat this process # 30 until requested. Of course, control may be performed so that the sensor load information request from the ECU 1 is received as an interrupt. When sensor load information is requested in process # 30, signal processing such as amplification of the output of gauge 3 is activated for signal processor 4 (process # 40), and communication IZ F part 15 of sensor 2 is activated. Sensor load information is output via (Process # 50). In this case, the signal processing Although it has been described that the signal processing by the processing unit 4 is driven, this is for ease of explanation. Of course, the electronic circuit may be steadily operated, and in the process # 40, the latest signal at that time may be extracted. In this way, the sensor load information force ECU1 output from the sensor 2 is acquired (see process # 60 in FIG. 3).

[Change of measurement reference value]

The outline of the present embodiment and the standard operation have been described above. The configuration and operation for changing the measurement reference value will be described below with reference to the drawings. FIG. 5 is a flowchart for explaining the measurement reference changing operation by the ECU of FIG. 2, and FIG. 6 is a flowchart for explaining the measurement reference changing operation of the sensor of FIG. Here, the measurement reference value is a value that determines the output of the sensor 2 as a load detection device in a no-load state where no occupant is present on the vehicle seat 20. Then, as an example of changing the measurement reference value, an example will be described in which an occupant is seated on the vehicle seat 20 and the V (zero) zero point reference when the seat is empty is adjusted.

[0034] As shown in FIG. 5, ECU1 confirms the request for adjusting the zero point reference, that is, the presence or absence of the zero point reset request (process # 1). This 0-point reset request is input from the inspection machine 40 connected to the ECU 1 at the time of vehicle inspection, for example. Alternatively, ECU 1 may execute a self-diagnosis program or the like, and issue a 0-point reset request according to the result. This self-diagnosis program has no load on the target vehicle seat 20 due to cooperation with other systems in the vehicle, such as when the vehicle stops and the passenger gets off and is locked. It can be done by recognizing that. In the present embodiment, for ease of explanation, a zero-point reset request is input from the detector 40, and based on this request, the EC Ul as the control device and the sensor 2 as the load detection device are measured reference values. The operation will be described below as executing the update process.

[0035] If the zero point reset request is disabled in process # 1, ECU1 performs normal operation as usual. That is, processing # 20, # 60, # 70, and # 80 are sequentially executed in the same manner as the operation described in FIG. 3, and the passengers on the vehicle seat 20 are determined. When this operation is performed only for inspection, as shown in FIG. 5, the occupant on the vehicle seat 20 is determined without confirming the passage of a fixed time (by omitting the processing # 10). You may do it. Process # 1 resets 0 points If the request is confirmed, a command is issued to adjust the deviation from the zero point for each sensor 21-25 (Process # 5).

[0036] Next, the operation of each of the sensors 21 to 25 (hereinafter represented by the sensor 2) will be described.

As shown in Fig. 6, first, the sensor load information request is checked (process # 30). When sensor load information is requested, sensor 2 performs standard operation as usual. That is, the processes # 40 and # 50 described with reference to FIG. 4 are sequentially executed. If there is no request for sensor load information, check whether there is a displacement adjustment command from ECU1 (Process # 35). If there is a misalignment command, the current output position of gauge 3 is set to the output reference position of sensor 2 (process # 36). This operation is performed to adjust the zero point. At this time, the vehicle seat 20 is in an empty seat state. Therefore, the zero point adjustment can be realized by setting the output of the gauge 3 at this point to the zero point output reference position of the sensor 2. In this way, according to an instruction from the ECU 1 as the control device, the sensor 2 as the load detection device executes the measurement reference value update process and updates the measurement reference value.

[0037] [Measurement reference value change example 1]

A specific example in which the measurement reference value is changed will be described below. FIG. 7 is a block diagram illustrating signal processing from the gauge of FIG. 2 to the AZD conversion unit, and FIG. 8 is a diagram illustrating AZD conversion by the AZD conversion unit of FIG.

[0038] The output of the gauge 3 is not large enough to be input to the AZD conversion unit 13 or the like as it is. In the present embodiment, as shown in FIG. 7, the output of the gauge 3 is amplified using an amplifier (amplifying circuit) 12a provided in the analog signal processing unit 12. Then, the output is input to the AZD converter 13 and subjected to analog Z-digital conversion (hereinafter referred to as AZD conversion) by the AZD converter 13a and the like. The AZD converter 13a digitally converts the voltage between the upper limit reference voltage (refH) and the lower limit reference voltage (refL) of the input analog voltage that is the target of AZD conversion with a predetermined resolution.

As shown in FIG. 8, it is assumed that the upper limit reference voltage and the lower limit reference voltage are set to IV and 3 V, respectively, and the AZD converter 13a has 6-bit resolution. In this case, when the output voltage of the amplified gauge 3 that changes linearly is IV, the digital value is 0 (zero), and when it is 3 V, the digital value is 63. The resolution per bit is 31.25mV It is. If the digital value is 16 when the above measurement reference value change command is issued (Process # 35 in Fig. 6), the gauge 3 after amplification when the vehicle seat 20 is empty is displayed. The output voltage is 1.5V. Therefore, since the voltage width of the AZD converter 13a up to the upper reference voltage of 3V is 1.5V, only a digital value of up to 48 can be obtained with a resolution of 31.25mV.

[0040] Therefore, the lower limit reference voltage of the AZD converter 13a is changed to 1.5V, which is the output voltage of the gauge 3 after amplification when the seat 20 is vacant, and the upper limit reference voltage is changed to the lower limit reference voltage. Change to 5V by adding 2V to the input width. Then, the upper and lower reference voltages of the AZD converter 13a stored in the storage unit 5 are changed to the new upper and lower reference voltages and stored. The upper and lower reference voltages of the AZD converter 13a are generated by a voltage generation circuit (not shown) based on the values stored in the storage unit 5 and input to the AZD converter 13a. As a result, it is possible to adjust the state when the vehicle seat 20 is empty while maintaining the resolution, that is, while maintaining the load measuring system using the gauge 3.

The measurement reference value is a value that determines the output of the sensor 2 as a load detection device in a no-load state where no occupant is present on the vehicle seat 20. Therefore, in the embodiment described above, the lower limit reference voltage (refL) corresponds to this. In addition, since the upper limit reference voltage (refH) is changed with the change of the lower limit reference voltage, both of these reference voltages correspond to the measurement reference value.

[0042] Further, the measurement reference value may be a value that defines a range that needs to be transmitted to the ECU 1 as the control device, among the loads that can be measured by the gauge 3 as the measurement unit. In the embodiment described above, the range that needs to be transmitted to the ECU 1 is determined by the upper limit reference voltage and the lower limit reference voltage, and therefore both these reference voltages correspond to measurement reference values. That is, as shown in FIG. 8, the effective data width of the load data to be transmitted to the ECU 1 is set to be W before and after the adjustment!

[0043] Further, if the input voltage range converted by the AZD converter 13a is widened, for example, the lower limit reference voltage is IV and the upper limit reference voltage is 4V, the effective data width of the load data to be transmitted to the ECU 1 is increased. Can be spread. Since the maximum value of the digitally converted value remains 63, the resolution is degraded. A wide range of loads (1.5 times in this example) Can be included in the effective load data. Conversely, if the input voltage range converted by the AZD converter 13a is narrowed, such as setting the lower limit reference voltage to IV and the upper limit reference voltage to 2V, the effective data width of the load data to be transmitted to ECU1 can be reduced. it can. Since the maximum value of the digitally converted value remains 63, the resolution increases. Only a narrow range of loads (in this case 1Z2 times) can be used as effective load data, but the accuracy is improved. As described above, the range that needs to be transmitted to the ECU 1 as the control device among the loads measurable by the gauge 3 as the measurement unit can be determined by the measurement reference value.

[Measurement reference value change example 2]

Another specific example for changing the measurement reference value will be described below. FIG. 9 is a diagram for explaining the signal processing of the gauge output in the analog signal processing unit of FIG. FIG. 10 is a diagram for explaining another example of the signal processing shown in FIG.

[0045] As shown in Fig. 9 (b), the output of the gauge 3 is a low voltage to be used as it is. For example, immediately after the first adjustment or as a design value (hereinafter, initial value), it is as follows. When the vehicle seat 20 is empty and the load WO is in an unloaded state, the output of the gauge 3 is 0. IV. When the maximum load W1 of the valid data of the load data to be transmitted to ECU1, the output of gauge 3 is 0.3V. The width force of this load WO and W1 The effective data width of the load data to be transmitted to ECU1. The output of the gauge 3 is amplified by the amplifier 12a of the analog signal processing unit 12 shown in FIG. 9 (a). In this example, the gain is amplified about 10 times based on the gain (gain) determined by the gain resistors 12b and 12c. The initial value of the virtual ground VG that serves as a reference for this amplification is ground (= OV), and the input to the AZD conversion unit 13 is from IV to 3V in the effective data width W. The gauge output voltage after amplification is AZD converted and transmitted to the ECU 1 as digital data.

[0046] Here, when the output voltage of the gauge 3 is deviated and the load WO is in a no-load state, it is 0.

Suppose that it becomes 15V. In the same way as above, when amplified with a gain of 10 times with reference to OV, which is the initial value of virtual ground VG, the effective data width W of the amplified gauge output voltage is 1.5 V force, etc. Between 5V. As a result, as shown in FIG. 9 (c), the upper and lower reference voltages of the AZD comparator 13a and the effective data width W of the amplified gauge output voltage become mismatched. Therefore, in the present embodiment, the value of the virtual ground VG of the amplifier 12a of the analog signal processing unit 12 shown in FIG. 9A can be set as the measurement reference value. The virtual ground VG that is the reference for amplification is in the initial state! /, Is the no-load state at the time of the most recent adjustment. The output voltage of the gauge 3 at the load WO and the gauge 3 at the current load WO Change to a value based on the difference from the output voltage. In this example, as described above, since it is 0.1V and 0.15V, the difference is 0.05V. Therefore, the value of virtual ground VG of amplifier 12a is set to 0.05V. By doing this, the effective data width W of the gauge output voltage after amplification is changed from IV to 3V, and the effective data width of the upper and lower reference voltages of the AZD converter 13a and the gauge output voltage after amplification. W is matched.

[0048] The measurement reference value is a value that determines the output of the sensor 2 as the load detection device in a no-load state where no occupant is present on the vehicle seat 20. Therefore, in this specific example, the value of the virtual ground VG of the amplifier 12a corresponds to this.

Further, as shown in FIG. 10 (a), the gain resistors 12b and 12c can be made variable, and the amplification factor determined by the gain resistors 12b and 12c can be used as the measurement reference value. The waveform A shown in FIG. 10 (b) is the same as the waveform example having no deviation from the waveform example shown in FIG. 9 (c). In other words, the output voltage of gauge 3, which is not displaced, is amplified about 10 times with the value of virtual ground VG of amplifier 12a set to 0 V. Therefore, the gauge output voltage after amplification is obtained so that the effective data width W is between the output loads WO and W1. Waveform B is obtained by amplifying the output voltage of gauge 3, which is also not displaced, with an amplification factor of about 20 times, and waveform C is amplified with an amplification factor of about 5 times. All of the waveforms A to C are set to have a load WO which is an unloaded state when the amplified voltage is IV.

[0050] Waveform B reaches 3V, which is the upper limit reference voltage of AZ D converter 13a, at the time of load W2 located approximately at the center of effective data width W of waveform A. On the other hand, waveform C has not yet reached 3V, which is the upper limit reference voltage of AZD converter 13a, at the time of maximum load W1 of effective data width W of waveform A. Waveform C reaches the upper reference voltage of 3V at a load W3 that is twice the load W1. In this way, by making the amplification rate of the analog signal processing unit 12 variable, it is possible to determine the range of the load that needs to be transmitted to the ECU 1. In other words, the amplification factor of the analog signal processing unit 12 is determined by the gauge 3 as the measurement unit. This corresponds to the measurement reference value, which is a value that defines the range that needs to be transmitted to the ECU 1 as the control device among the measurable loads. In the example described in FIG. 10, it is necessary to appropriately set the value of the virtual ground VG of the amplifier 12a when obtaining the waveform B and the waveform C. In this case, the value of the virtual ground VG also corresponds to the measurement reference value. Become. Values such as the amplification factor and virtual ground VG used in the analog signal processing unit 12 are stored in the storage unit 5 and appropriately updated as described above.

[0051] In the above example, the initial value of the virtual ground VG value of the amplifier 12a has been described as ground = OV. Then, for example, the value of the virtual ground VG for obtaining the waveform B is 0.05 V, and the value of the virtual ground VG for obtaining the waveform C is minus 0.1 V. That is, it can be considered complicated, for example, a negative power source is required. However, this is only an example used for ease of explanation and there is no problem. For example, a clamp circuit that uniformly applies a constant voltage to the output voltage of the gauge 3 is provided in the analog signal processing unit 12. Then, a constant voltage (clamp voltage) applied uniformly is set as the initial value of the virtual ground VG. Then, there is a section with a positive potential between the clamp voltage and ground, so a negative power supply is not necessary.

In the description of the embodiment, the sensor 2 as the load detection device has the AZD conversion unit 13 and the digital data is used when the load data is output to the ECU 1 as the control device. The load data may be output to ECU1. As explained in Example 2 of changing the measurement reference value, when the value used in the analog signal processing unit 12 is configured as the measurement reference value, the load data is output to the ECU 1 as analog data. Also, the present invention is applicable.

As described above, according to the present invention, it is possible to provide a vehicle occupant detection device capable of detecting a load on a vehicle seat and detecting an occupant on the vehicle seat with high accuracy without impairing noise resistance. it can.

Industrial applicability

The present invention detects an occupant detection device for a vehicle that detects a load on a vehicle seat installed in an automobile, a railway vehicle, or the like, and determines an occupant on the vehicle seat based on the detected load data. Can be used. Brief Description of Drawings

FIG. 1 is a schematic diagram showing an arrangement of each part of a vehicle occupant detection device according to an embodiment of the present invention. FIG. 2 is a block diagram showing a system configuration of a vehicle occupant detection device according to an embodiment of the present invention.

FIG. 3 is a flowchart for explaining the standard operation of the ECU in FIG.

FIG. 4 is a flowchart for explaining the standard operation of the sensor of FIG.

FIG. 5 is a flowchart for explaining the measurement standard changing operation by the ECU of FIG.

FIG. 6 is a flowchart for explaining the measurement standard changing operation of the sensor in FIG.

[Fig. 7] Block diagram explaining the signal processing up to the gauge force AZD converter in Fig. 2

[Fig.8] Diagram explaining AZD conversion by AZD converter in Fig.7

FIG. 9 is a diagram for explaining signal processing of gauge output in the analog signal processing unit of FIG.

FIG. 10 is a diagram for explaining another example of the signal processing shown in FIG.

Explanation of symbols

[0056] 1 ECU

2 Sensor

3 gauge

§Self 'I p ^: [5

Claims

The scope of the claims

[1] A vehicle occupant detection device including a load detection device that detects a load on a vehicle seat and a control device that determines an occupant based on load data input to the load detection device force,

The load detection device includes a measurement unit that measures a load, and a storage unit that stores a measurement reference value that defines a measurement reference by the measurement unit,

The vehicle occupant detection device is configured such that the storage unit includes rewritable and nonvolatile storage means.

2. The vehicle occupant detection device according to claim 1, wherein the measurement reference value is a value that defines an output of the load detection device in a no-load state where no occupant is present on the vehicle seat.

[3] The vehicle occupant detection device according to claim 1, wherein the measurement reference value is a value that defines a range that needs to be transmitted to the control device among loads measurable by the measurement unit.

[4] The vehicle occupant according to any one of claims 1 to 3, wherein the load detection device executes a measurement reference value update process and updates the measurement reference value according to an instruction from the control device. Detection device.

5. The vehicle occupant detection device according to claim 1, wherein the load detection device and the control device perform two-way communication.

6. The vehicle occupant detection device according to claim 5, wherein the bidirectional communication has a variable communication speed.

[7] The vehicle occupant detection device according to claim 1, wherein the occupant discrimination information by the control device is transmitted to another control device of the vehicle.

8. The vehicle occupant detection device according to claim 7, wherein the other control device is an airbag control device.

[9] The vehicle occupant detection device according to claim 1, wherein the control device is connectable to an inspection machine via an interface.

[10] The inspection machine performs one or both of inspection and calibration of the load detection device. Item 10. The vehicle occupant detection device according to Item 9.

2. The vehicle occupant detection device according to claim 1, wherein the load detection device is interposed between the vehicle seat and a seat rail installed on the vehicle side.

The vehicle occupant detection device according to claim 1, wherein the load detection device includes a strain sensor.