JP2018096693A - Ultrasonic sensor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultrasonic sensor device which compensates for influence due to temperature and humidity with a simple configuration.SOLUTION: An ultrasonic sensor device 100 has a temperature measuring unit 9 having an outside air temperature instrument 10 for measuring outside air temperature and a control unit 5. The control unit 5 comprises a distance computation unit 6 for measuring a distance to an obstacle 3, a correction unit 7 having a correction value for correcting a measurement error due to a temperature characteristic of an ultrasonic wave when the distance computation unit 6 measures the distance to the obstacle 3, and a determination unit 12 for determining whether or not the outside air temperature instrument 10 is normal. The correction unit 7 outputs a correction value based on the outside air temperature acquired by the temperature measuring unit 9 to the distance computation unit 6 when the determination unit 12 determines that the outside air temperature instrument 10 is normal. The distance computation unit 6 corrects the measured distance based on the correction value.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an ultrasonic sensor device that measures a distance to an obstacle based on a time difference from transmission to reception of ultrasonic waves.

  There has been proposed an ultrasonic sensor device capable of solving the problem of detection accuracy deterioration due to humidity change. (For example, see Patent Document 1)

JP 2006-242650 A

  However, since the ultrasonic sensor device of Patent Document 1 needs to transmit a plurality of ultrasonic waves having different frequencies, the ultrasonic sensor device becomes complicated. Therefore, an object of the present invention is to provide an ultrasonic sensor device in which the influence of temperature or humidity is corrected while simplifying the configuration.

  An ultrasonic sensor device of the present disclosure made to achieve such an object is an ultrasonic sensor device that is mounted on a vehicle and measures a distance to an obstacle based on a time difference from transmission to reception of ultrasonic waves. A temperature measuring unit having an outside air thermometer for measuring the outside temperature, and a control unit, the control unit measuring a distance to the obstacle, and the distance calculating unit calculating the distance to the obstacle. A correction unit having a correction value for correcting a measurement error due to the temperature characteristic of the ultrasonic wave at the time of measurement, and a determination unit that determines whether or not the outside air thermometer is normal. When the meter is determined to be normal, the temperature measurement unit outputs a correction value based on the outside air temperature acquired to the distance calculation unit, and the distance calculation unit corrects the distance measured based on the correction value. And

  The ultrasonic sensor device of the present disclosure can accurately measure the distance to an obstacle by correcting the influence of temperature or humidity while suppressing an increase in the size of the ultrasonic sensor device, a complicated system, and an increase in manufacturing cost. .

The block diagram of the ultrasonic sensor apparatus 100 which concerns on embodiment of this invention. The flowchart explaining operation | movement of the control part 5 of FIG.

(Knowledge that became the basis of the present invention)
The present inventor has found that the following problems occur with respect to the ultrasonic sensor device described in the “Background Art” column.

2. Description of the Related Art Conventionally, an in-vehicle ultrasonic sensor device that receives a reflected wave of an ultrasonic wave transmitted from a transmission unit at a reception unit and measures a distance to an obstacle based on a time difference from transmission to reception is known. However, ultrasonic waves have a characteristic that their speed and sound pressure change due to environmental changes such as temperature and humidity. Therefore, in order to accurately detect an obstacle by the ultrasonic sensor device, it is necessary to correct the distance to the obstacle calculated by the ultrasonic sensor device after grasping the temperature and humidity at the time of measurement.

  Therefore, an ultrasonic sensor device that can solve the problem of deterioration in detection accuracy due to a change in humidity as in Patent Document 1 has been proposed. In this ultrasonic sensor device, one or more transmission elements and two or more reception elements are integrated on the same substrate, and the transmission elements transmit ultrasonic waves of two or more different frequencies, and receive corresponding to each. Humidity correction is performed by calculating the attenuation loss of the signal.

  However, in the ultrasonic sensor device of Patent Document 1, it is necessary to transmit a plurality of ultrasonic waves having different frequencies, and since a plurality of receiving elements are required, the size of the ultrasonic sensor device and the complexity of the system are increased. There is a problem that the manufacturing cost increases.

  In order to solve such a problem, an ultrasonic sensor device according to an aspect of the present invention is mounted on a vehicle and measures the distance to an obstacle based on a time difference from transmission to reception of ultrasonic waves. A temperature measuring unit having an outside air thermometer for measuring an outside temperature and a control unit, the control unit measuring a distance to an obstacle, and the distance calculating unit being an obstacle A correction unit having a correction value that corrects a measurement error due to the temperature characteristic of the ultrasonic wave when measuring the distance to, and a determination unit that determines whether or not the outside air thermometer is normal. Outputs a correction value based on the outside air temperature acquired by the temperature measurement unit to the distance calculation unit, and the distance calculation unit corrects the measured distance based on the correction value. To do.

  According to this, since the correction unit outputs a correction value based on the outside air temperature to the distance calculation unit, the ultrasonic sensor device can accurately measure the distance to the obstacle without being affected by the temperature. Moreover, since a plurality of receiving elements are not required, it is possible to suppress an increase in the size of the ultrasonic sensor device, a complicated system, and an increase in manufacturing cost. Furthermore, since the correction unit does not perform correction except when the determination unit determines that the outside air thermometer is normal, correction based on the measurement value erroneously measured by the outside air thermometer can be suppressed.

  In addition, for example, a humidity measuring unit having an outside air hygrometer for measuring outside air humidity is further provided, and the correction value is a correction value for correcting a measurement error due to the temperature characteristic and the humidity characteristic of the ultrasonic wave, A correction value based on the outside air temperature acquired by the unit and the outside air humidity acquired by the humidity measuring unit may be output to the distance calculating unit.

  According to this, since the correction unit outputs a correction value based on the outside air temperature and the outside air humidity to the distance calculation unit, the ultrasonic sensor device can accurately measure the distance to the obstacle without being affected by the temperature and humidity. .

  In addition, for example, the distance calculation unit may correct the measured distance when the speed measured by the speed measurement unit that measures the speed of the vehicle is larger than the speed threshold.

  According to this, when the vehicle speed exceeds a certain level, the distance measured by the distance correction unit is corrected, so that the measurement error can be corrected at a temperature and / or humidity closer to the outside air.

  In addition, for example, the control unit further includes a time measurement unit that measures an elapsed time from when the determination unit determines that the outside air thermometer is normal, and the time measurement unit has a determination unit that the outside air thermometer is normal The distance calculation unit may correct the measured distance when the elapsed time is equal to or greater than a predetermined time threshold.

  According to this, in order to correct the distance measured by the distance calculation unit when the vehicle keeps a certain speed or more for a certain time, the temperature and / or humidity measured by the outside air thermometer and / or outside air hygrometer, respectively. Measurement error can be corrected after the signal becomes sufficiently stable.

  For example, the control unit may further include an update unit that determines a timing at which the correction unit updates the correction value.

  According to this, even when the temperature or humidity changes, the distance to the obstacle can be accurately measured by updating the correction value.

  For example, the update unit may permit the correction unit to update the correction value when the correction unit outputs the correction value to the distance calculation unit.

  According to this, every time the correction unit outputs the correction value to the distance calculation unit, the correction unit calculates a new correction value, so that the distance to the obstacle can be accurately measured.

  For example, the update unit may allow the correction unit to update the correction value when the change amount of the outside air temperature exceeds a predetermined temperature change amount threshold value.

  According to this, even when the temperature changes rapidly, the ultrasonic sensor device can accurately measure the distance to the obstacle.

  Further, for example, the update unit may permit the correction unit to update the correction value when the change amount of the outside air humidity exceeds a predetermined humidity change amount threshold value.

  According to this, even when the humidity changes abruptly, the ultrasonic sensor device can accurately measure the distance to the obstacle.

  Hereinafter, embodiments will be specifically described with reference to the drawings. In the following description, the same or corresponding elements are denoted by the same reference symbols throughout the drawings, and redundant description thereof is omitted. Each of the embodiments described below shows a comprehensive or specific example. The constituent elements, the positions and connection forms of the constituent elements, the steps, the order of the steps, and the like shown in the following embodiments are merely examples, and are not intended to limit the present invention. In addition, among the constituent elements in the following embodiments, constituent elements that are not described in the independent claims indicating the highest concept are described as optional constituent elements.

  The ultrasonic sensor device 100 according to the present embodiment is mounted on a vehicle, transmits and receives ultrasonic waves, and measures a distance to an obstacle based on a time difference from transmission to reception. For example, when the distance to the obstacle is short, the driver is notified and the vehicle is controlled.

  First, the configuration of the ultrasonic sensor device 100 will be described. FIG. 1 is a block diagram showing the configuration of the ultrasonic sensor device 100. The ultrasonic sensor device 100 includes a transmission unit 1, a reception unit 2, a reception amplification unit 4, a control unit 5, a temperature measurement unit 9, and a humidity measurement unit 18. The control unit 5 includes a distance calculation unit 6, a correction unit 7, a determination unit 12, a time measurement unit 13, and an update unit 16. The control unit 5 is connected to a speed measurement unit 15 and a vehicle control unit 17 mounted on the vehicle.

  The transmission unit 1 includes an ultrasonic microphone using a piezoelectric element, transmits an ultrasonic wave having a frequency equal to the input oscillation signal to the obstacle 3, and an electric signal corresponding to the transmitted ultrasonic wave is a distance calculation unit. 6 is output. The transmitted ultrasonic wave is reflected by the obstacle 3.

  The receiving unit 2 is composed of an ultrasonic microphone using a piezoelectric element like the transmitting unit 1, receives the ultrasonic wave reflected by the obstacle 3, converts it into an electric signal, and outputs it to the wave receiving / amplifying unit 4. The transmission unit 1 and the reception unit 2 may be integrated or may exist as separate bodies. Also, a plurality of transmission units 1 and reception units 2 may be installed, and the number of transmission units 1 and reception units 2 may not be the same.

  The reception amplification unit 4 amplifies the electrical signal received by the reception unit 2 and outputs it to the distance calculation unit 6.

  The temperature measurement unit 9 includes an outside air thermometer 10 and a vehicle thermometer 11 which are sensing devices that measure the temperature of the outside air. The outside air thermometer 10 and the vehicle thermometer 11 are installed in a vehicle bumper, for example, and measure the temperature of outside air.

  Although the outside temperature thermometer 10 and the vehicle thermometer 11 included in the temperature measuring unit 9 are not particularly distinguished, the temperature measuring unit 9 preferably includes a plurality of sensing devices that measure the temperature of the outside air. The measured outside air temperature is output to the determination unit 12 as an electrical signal.

  The speed measurement unit 15 measures the vehicle speed V (t). As a method for detecting the speed of the vehicle, for example, there is a method for detecting the vehicle speed by a driven gear provided on the output side of the transmission. The measured vehicle speed is output to the time measuring unit 13.

  The humidity measuring unit 18 includes an outside air hygrometer 19 that measures the humidity of the outside air. The outside humidity measured by the humidity measuring unit 18 is sent to the correcting unit 7.

  The control unit 5 includes a microcomputer, a RAM (Random Access Memory), and a ROM (Read Only Memory) that stores a program and data for causing the microcomputer to execute a control process described later.

  The distance calculation unit 6 calculates the distance to the obstacle 3 based on the electrical signals output from the transmission unit 1 and the reception amplification unit 4. Specifically, the distance to the obstacle 3 is measured based on the time difference from the transmission to the reception of the ultrasonic wave from the signals output from the transmission unit 1 and the reception amplification unit 4. Further, as will be described later, the measured distance is corrected from a correction value based on temperature and / or humidity. The calculated distance is output to the vehicle control unit 17 as an electrical signal.

  The correction unit 7 corrects the measurement error due to temperature and humidity with respect to the distance to the obstacle 3. The correction unit 7 has a correction table. The correction table is a table for determining a correction value from the outside air temperature and the outside air humidity. For example, the temperature may be arranged in a row and the humidity may be arranged in a column, and a correction value may be entered in a column corresponding to the matrix. Then, the correction unit 7 calls the correction value corresponding to the outside air temperature acquired from the temperature measurement unit 9 and the outside air humidity acquired from the humidity measurement unit 18 when necessary, and outputs the correction value to the distance calculation unit 6.

  The correction table is not limited to the configuration in which the correction value corresponds to the temperature and the humidity as described above. For example, the correction table may correspond to the temperature only, or the correction value corresponds to only the humidity. It may be a table like this. In this way, since the correction value can be determined by only one of the outside air temperature and the outside air humidity, the temperature measuring unit 9 and the humidity measuring unit 18 may be provided.

  The determination unit 12 determines whether or not the outside air thermometer 10 is normal based on the temperatures measured by the outside air thermometer 10 and the vehicle thermometer 11. The determination result and the acquired outside air temperature are sent to the time measuring unit 13 and the updating unit 16.

The time measurement unit 13 measures an elapsed time W after the determination unit 12 determines that the outside air thermometer 10 is normal. The time measurement unit 13 sends the outside temperature acquired from the determination unit 12 and the speed acquired from the speed measurement unit 15 to the correction unit 7 in addition to the measured elapsed time W.

  The update unit 16 determines the timing at which the correction unit 7 updates the correction value. The update unit 16 permits an update to the next correction value when the correction unit 7 outputs the correction value to the distance calculation unit 6. Thereby, the correction unit 7 selects a correction value from the correction table based on the new outside air temperature and outside air humidity. The selected correction value is output to the distance calculation unit 6.

  The update may be performed at regular intervals. Further, the update unit 16 acquires the outside air temperature determined to be normal from the determination unit 12, and the next update is performed when the temperature change from the outside air temperature at the previous update exceeds a predetermined change amount. May be allowed. Similarly, the update unit 16 acquires the outside air humidity from the humidity measuring unit 18, and permits the next update when the humidity change from the outside air humidity at the time of the previous update exceeds a predetermined change amount. May be. For example, the update may be performed at a predetermined time such as 10 am, 2 pm, or 6 pm.

  The vehicle control unit 17 controls the vehicle based on the distance to the obstacle 3 calculated by the distance calculation unit 6. For example, when the calculated distance is smaller than a predetermined distance threshold, the vehicle control unit 17 performs braking control of the vehicle. Instead of performing the braking control, the vehicle control unit 17 may notify the driver of a warning sound notifying the presence of the obstacle 3 or displaying a warning on a display such as a navigation device. With this configuration, the ultrasonic sensor device 100 controls the vehicle after correcting the measurement distance error due to the temperature and / or humidity characteristics, so that the vehicle can be controlled more safely and accurately.

  Next, operation | movement of the control part 5 is demonstrated using FIG. FIG. 2 is a flowchart for explaining the operation of the control unit 5 of FIG.

  The ultrasonic sensor device 100 is turned on when the car engine is ignited (or powered on). When the ultrasonic sensor device 100 is powered on, the flow moves to step S1.

  In step S1, the determination unit 12 determines whether or not the outside air thermometer 10 is normal. Assume that the outside air thermometer 10 indicates the temperature T1 (t) at time t. The vehicle thermometer 11 indicates the temperature T2 (t) at the same time t. At this time, when the difference between T1 (t) and T2 (t) is smaller than the predetermined temperature threshold value TH1 (YES in step S1), the determination unit 12 determines that the outside air thermometer 10 is normal and the flow Shifts to S2.

  The determination unit 12 can determine whether the outside air thermometer 10 is normal by comparing the temperature T1 (t) indicated by the outside air thermometer 10 with the temperature T2 (t) indicated by the vehicle thermometer 11. . Thus, since the determination part 12 determines whether the outside temperature thermometer 10 is operate | moving correctly, the incorrect correction | amendment based on the temperature which the malfunctioning outside temperature thermometer 10 measured incorrectly can be suppressed.

  In step S1, when the difference between T1 (t) and T2 (t) is equal to or greater than a predetermined temperature threshold TH1 (NO in step S1), the determination unit 12 determines that the outside air thermometer 10 is abnormal, Return to step S1.

  In step S2, the time measuring unit 13 measures time. The time measuring unit 13 measures an elapsed time W after it is determined in step S1 that the outside air thermometer 10 is normal. When the time measuring unit 13 measures the elapsed time, the flow moves to step S3.

In step S <b> 3, the vehicle speed V (t) measured by the speed measurement unit 15 by the time measurement unit 13.
Is compared with a predetermined speed threshold value TH2. When vehicle speed V (t) is equal to or higher than speed threshold value TH2 (YES in step S3), the flow proceeds to step S4. In step S3, when the vehicle speed V (t) is smaller than the speed threshold TH2 (NO in step S3), the flow proceeds to step S5. In step S5, the elapsed time W is reset to zero. Thereafter, the flow returns to step S2.

  In step S4, the elapsed time W measured by the time measuring unit 13 is compared with the time threshold value TH3. When the elapsed time W is equal to or greater than the time threshold value TH3 (YES in step S4), the flow proceeds to S6. In step S4, when the elapsed time W is smaller than the time threshold value TH3 (NO in step S4), the flow is returned to S2.

  In step S6, the correction unit 7 selects and calls a correction value corresponding to the outside air temperature and the outside air humidity from the correction table. The correction table is a correspondence table in which temperature and humidity are associated with correction values. However, as described above, it may be a table in which only the temperature, only the humidity, and the correction value are associated with each other.

  The called correction value is output to the distance calculation unit 6. When the correction value is output to the distance calculation unit 6, the flow moves to step S7.

  In step S7, the distance calculation unit 6 calculates the distance to the obstacle 3 in which the measurement error due to the temperature and / or humidity characteristics of the ultrasonic sensor device 100 is corrected based on the output correction value. The calculated distance is output to the vehicle control unit 17 as an electrical signal. After calculating the distance to the obstacle 3, the flow moves to step S8.

  In this way, when the vehicle maintains a speed above a certain level for a certain time or longer, the correction unit 7 outputs a correction value based on the outside air temperature and the outside air humidity to the calling distance calculation unit 6, so that the measured temperature and humidity are Measurement error can be corrected in a sufficiently stable state.

  For example, when the outside air thermometer 10 is installed in a vehicle bumper that tends to become hot when the vehicle stops, the temperature measured by the outside air thermometer 10 when the vehicle starts moving is the actual outside air temperature and humidity. It is possible to measure different values. By setting a vehicle speed restriction on the correction timing, the outside air thermometer 10 and the outside air hygrometer 19 are exposed to the outside air. Accordingly, the outside air thermometer 10 and the outside air hygrometer 19 can accurately measure the temperature and humidity of the outside air.

  Furthermore, by providing a restriction on elapsed time in the correction timing, the outside air thermometer 10 and the outside air hygrometer 19 are sufficiently exposed to the outside air. Thereby, since the measured value is stabilized, the outside air thermometer 10 and the outside air hygrometer 19 can measure the accurate temperature and humidity of the outside air, respectively.

  In step S8, the update unit 16 determines the update timing of the correction value. For example, when the correction unit 7 outputs the correction value to the distance calculation unit (YES in step S8), the correction value is updated by the correction unit 7, and the flow returns to step S1. Thereby, since it is updated to the correction value according to the outside air temperature and outside air humidity at the time of measurement at any time, the distance to the obstacle 3 can be accurately measured even when the outside air temperature and the outside air humidity change.

  As described above, the update timing is not limited to this case. The update may be performed at regular intervals, or when the temperature change or humidity change from the previous update exceeds a predetermined change (temperature change threshold or humidity change threshold). Also good. For example, the update may be performed at a predetermined time such as 10 am, 2 pm, or 6 pm. When the temperature change amount and the humidity change amount exceed a predetermined change amount, it is possible to cope with a sudden change in temperature and humidity.

  By repeating the above flow, the ultrasonic sensor device 100 can measure the distance to the obstacle 3 with high accuracy regardless of the temperature and humidity around the vehicle with a simple configuration. Moreover, since the correction | amendment part 7 does not correct | amend except when the determination part 12 judges that the outside temperature thermometer 10 is normal, it can suppress the incorrect correction | amendment based on the value which the outside temperature thermometer 10 measured incorrectly.

  Further, the distance to the obstacle 3 in which measurement errors due to temperature and humidity are corrected may be compared with a predetermined distance threshold, and the vehicle control unit 17 may control the vehicle according to the result. Thereby, since the vehicle is controlled after correcting the measurement distance error, the vehicle can be controlled more safely and accurately. As a control method, braking control such as automatic braking or alarm sound notification can be considered.

  The ultrasonic sensor device 100 of the present invention has an effect that the distance to the obstacle 3 can be accurately measured by correcting the influence of temperature while suppressing the increase in the size of the device, the complexity of the system, and the increase in manufacturing cost. It is useful for an ultrasonic sensor device for vehicles.

DESCRIPTION OF SYMBOLS 1 Transmission part 2 Reception part 3 Obstacle 4 Receive amplification part 5 Control part 6 Distance calculation part 7 Correction | amendment part 9 Temperature measurement part 10 Outside temperature thermometer 11 Vehicle thermometer 12 Determination part 13 Time measurement part 15 Speed measurement part 16 Update part 17 Vehicle Control Unit 18 Humidity Measurement Unit 19 Outside Air Hygrometer 100 Ultrasonic Sensor Device

Claims (8)

In an ultrasonic sensor device that is mounted on a vehicle and measures the distance to an obstacle based on the time difference from transmission to reception of ultrasonic waves,
A temperature measuring unit having an outside air thermometer for measuring the outside air temperature;
A control unit,
The controller is a distance calculator that measures the distance to the obstacle;
A correction unit having a correction value for correcting a measurement error due to the temperature characteristic of the ultrasonic wave when the distance calculation unit measures the distance to the obstacle;
A determination unit for determining whether or not the outside air thermometer is normal,
When the determination unit determines that the outside air thermometer is normal, the correction unit outputs the correction value based on the outside air temperature acquired by the temperature measurement unit to the distance calculation unit,
The ultrasonic sensor apparatus, wherein the distance calculation unit corrects a distance measured based on the correction value. It further comprises a humidity measurement unit having an outside air hygrometer that measures outside air humidity,
The correction value is a correction value for correcting a measurement error due to temperature characteristics and humidity characteristics of ultrasonic waves,
The supervising unit according to claim 1, wherein the correcting unit outputs the correction value based on the outside air temperature acquired by the temperature measuring unit and the outside air humidity acquired by the humidity measuring unit to the distance calculating unit. Sound wave sensor device.   The said distance calculating part correct | amends the measured distance, when the speed measured by the speed measurement part which measures the speed of the said vehicle is larger than a speed threshold value, The Claim 1 or Claim 2 characterized by the above-mentioned. Ultrasonic sensor device. The control unit further includes a time measurement unit that measures an elapsed time from when the determination unit determines that the outside air thermometer is normal,
The time measurement unit starts measurement when the determination unit determines that the outside air thermometer is normal,
The ultrasonic sensor apparatus according to claim 3, wherein the distance calculation unit corrects the measured distance when the elapsed time is equal to or greater than a predetermined time threshold value.   The ultrasonic sensor device according to claim 1, wherein the control unit further includes an update unit that determines a timing at which the correction unit updates a correction value.   The ultrasonic sensor device according to claim 5, wherein the update unit permits the correction value to be updated by the correction unit when the correction unit outputs the correction value to the distance calculation unit.   The ultrasonic sensor device according to claim 5, wherein the update unit permits the correction value to be updated by the correction unit when a change amount of the outside air temperature exceeds a predetermined temperature change amount threshold value. . The control unit further includes an update unit that permits update of the correction value by the correction unit,
The ultrasonic sensor device according to claim 2, wherein the update unit permits the correction unit to update the correction value when the change amount of the outside air humidity exceeds a predetermined humidity change amount threshold value. .