Object detection system

Abstract

The present application relates to an object detection system having a plurality of object detection units each having a transceiver of ultrasonic waves and a temperature sensor, and achieving improvement of object detection accuracy based on a possibility of failure of the temperature sensor. An object detection system as one example of the present application has a plurality of object detection units each having: a transceiver that transmits ultrasonic waves and receives reflected waves generated by reflection of the ultrasonic waves by an object; a reception circuit unit that detects a signal level of the reflected waves received by the transceiver; a detection unit that detects an object by comparing the signal level detected by the reception circuit unit with a predetermined signal threshold; a temperature sensor that detects a temperature of an environment; and a detection sensitivity adjustment unit that adjusts a detection sensitivity of the reception circuit unit based on a second lowest temperature among temperatures respectively detected by the temperature sensors of the plurality of object detection units.

Description

Technical Field

[0001] This invention relates to an object detection system. Background Technology

[0002] Previously, there were techniques, such as those used in vehicles (cars, etc.), that detected objects by sending ultrasonic waves outwards and receiving the reflected waves from objects (walls, other vehicles, pedestrians, etc.). Furthermore, the attenuation and propagation speed of ultrasonic waves in the air (outside air) vary depending on the air temperature (hereinafter referred to as outside temperature). Therefore, if the correct outside temperature can be identified (or inferred), the accuracy of object detection can be improved.

[0003] However, setting up a sensor solely for detecting external air temperature is not cost-effective. Therefore, when the object detection unit is equipped with a temperature sensor that detects ambient temperature (ambient air temperature), the external air temperature can be inferred based on the temperature detected by that temperature sensor.

[0004] However, due to the location of the object detection unit, the temperature sensor is often affected by engine exhaust heat, direct sunlight, etc., and detects a temperature significantly higher than the outside temperature, thus failing to accurately infer the outside temperature.

[0005] Therefore, there exists a technique that, in cases with multiple object detection units, infers the lowest temperature among the temperatures detected by each temperature sensor as the external air temperature, and performs object detection based on that external air temperature. This achieves a certain level of effectiveness.

[0006] Patent Document 1: Japanese Patent No. 6413622

[0007] However, in the aforementioned prior art, for example, when a temperature sensor that detects the lowest temperature malfunctions and detects an abnormally low temperature, there is a problem such as a significant reduction in the accuracy of object detection. Summary of the Invention

[0008] Therefore, one of the objectives of this invention is to improve the object detection accuracy in an object detection system that includes multiple object detection units equipped with ultrasonic transceivers and temperature sensors, based on the possibility of temperature sensor malfunction.

[0009] An object detection system, as an example of the present invention, includes: a plurality of object detection units, each object detection unit comprising: a transceiver unit that transmits ultrasonic waves and receives reflected waves generated by the ultrasonic waves being reflected by an object; a receiving circuit unit that detects the signal level of the reflected waves received by the transceiver unit; a detection unit that detects an object by comparing the signal level detected by the receiving circuit unit with a predetermined signal threshold; a temperature sensor that detects the temperature of the environment; and a detection sensitivity adjustment unit that adjusts the detection sensitivity of the receiving circuit unit based on the second lowest temperature among the temperatures detected by the temperature sensors of the plurality of object detection units.

[0010] Based on this structure, the detection sensitivity of the receiving circuit is adjusted according to the second lowest temperature among the temperatures detected by multiple temperature sensors, thereby improving the accuracy of object detection based on the possibility of temperature sensor failure.

[0011] Furthermore, in the aforementioned object detection system, which is installed in a vehicle, the detection sensitivity adjustment unit adjusts the detection sensitivity of the receiving circuit based on the second lowest temperature among the temperatures detected by the temperature sensors of the multiple object detection units, provided that the vehicle meets the pre-set driving conditions based on the cooling of the ambient temperature caused by the driving wind.

[0012] Based on this structure, under the aforementioned driving conditions, by adjusting the detection sensitivity of the receiving circuit section, it is possible to further improve the object detection accuracy by cooling each temperature sensor through the driving wind caused by the vehicle's movement.

[0013] Furthermore, in the aforementioned object detection system, the temperature sensor periodically detects the temperature of the environment. The detection sensitivity adjustment unit sets the second lowest temperature as the external temperature estimation value when the second lowest temperature is lower than the most recent external temperature estimation value. When the second lowest temperature is higher than or lower than the value obtained by adding a predetermined temperature rise threshold to the most recent external temperature estimation value, the unit sets the value calculated using the second lowest temperature and the most recent external temperature estimation value based on a predetermined formula as the external temperature estimation value. When the second lowest temperature is higher than or higher than the value obtained by adding the predetermined temperature rise threshold to the most recent external temperature estimation value, the unit sets the most recent external temperature estimation value as the external temperature estimation value. The detection sensitivity of the receiving circuit unit is adjusted based on the latest external temperature estimation value.

[0014] Based on this structure, by comparing the second lowest temperature with the most recent external temperature estimate, and the value obtained by adding a predetermined temperature rise threshold to the most recent external temperature estimate, the external temperature estimate can be set to a more appropriate value, thereby further improving the accuracy of object detection. Attached Figure Description

[0015] Figure 1 This is an illustrative and schematic diagram showing the appearance of a vehicle equipped with the object detection system of the first embodiment as viewed from above.

[0016] Figure 2 This is an exemplary and schematic block diagram showing the functional structure of the object detection system according to the first embodiment.

[0017] Figure 3 This is an exemplary and schematic flowchart illustrating a series of processes performed by the object detection unit of the first embodiment.

[0018] Figure 4 This is an exemplary and schematic flowchart illustrating a series of processes performed by the object detection unit in the second embodiment.

[0019] Explanation of reference numerals in the attached figures

[0020] 1…vehicle, 2…vehicle body, 3F…front wheel, 3R…rear wheel, 20…object detection device, 100…ECU, 110…input / output unit, 120…storage unit, 130…processor, 200…object detection unit, 201…input / output unit, 202…temperature sensor, 203…transmit / receive control unit, 204…transmitting circuit unit, 205…transmit / receive unit, 206…receiving circuit unit, 207…detection sensitivity adjustment unit, 208…detection unit, O…object, RS…road surface. Detailed Implementation

[0021] Hereinafter, embodiments of the object detection system of the present invention (first embodiment and second embodiment) will be described with reference to the accompanying drawings. Furthermore, the structures, functions, and effects of the embodiments described below are merely examples, and the present invention is not limited to the following description.

[0022] (First Implementation)

[0023] Figure 1This is an illustrative and schematic diagram showing the exterior of the vehicle according to the object detection system of the first embodiment, viewed from above. The object detection system includes an ECU (Electronic Control Unit) 100 as an onboard control device and an object detection device 20 as an onboard sonar. The object detection device 20 is composed of object detection units 200a to 200d. The ECU 100 is mounted inside a four-wheeled vehicle 1, which includes a pair of front wheels 3F and a pair of rear wheels 3R. In addition, the object detection units 200a to 200d are mounted on the exterior of the vehicle 1.

[0024] exist Figure 1 In this example, although the object detection units 200a to 200d are located at different positions on the rear end (rear bumper) of the vehicle body 2, which is part of the vehicle 1, the positions of the object detection units 200a to 200d are not limited to this. For example, the object detection units 200a to 200d may also be located on the front end (front bumper) of the vehicle body 2, on the side of the vehicle body 2, or on two or more of the rear end, front end, and side.

[0025] Furthermore, in the embodiments, the object detection units 200a to 200d have the same hardware structure and function. Therefore, for the sake of simplicity, the object detection units 200a to 200d will also be referred to as "object detection unit 200" without distinction. Additionally, the number of object detection units 200 is not limited to this. Figure 1 The four shown.

[0026] Figure 2 This is an exemplary and schematic block diagram showing the functional structure of the object detection system according to the first embodiment. Furthermore, in Figure 2 In this context, lines and arrows connecting two structures represent the main flow of information. Information can also flow between structures that are not connected by lines, or information can flow in the opposite direction of the arrow.

[0027] The ECU 100 has the same hardware structure as a typical computer. More specifically, the ECU 100 includes an input / output unit 110, a storage unit 120, and a processor 130.

[0028] The input / output unit 110 is an interface for transmitting and receiving information between itself and the object detection unit 200.

[0029] The storage unit 120 includes main storage devices such as ROM (Read Only Memory) and RAM (Random Access Memory), and / or auxiliary storage devices such as HDD (Hard Disk Drive) and SSD (Solid State Drive).

[0030] The processor 130 is responsible for various processes performed in the ECU 100. The processor 130 includes, for example, a computing device such as a CPU (Central Processing Unit). The processor 130 reads and executes computer programs stored in the storage unit 120 to implement various functions such as automatic parking.

[0031] Furthermore, the object detection unit 200 is configured with the same hardware structure as a typical computer. More specifically, the object detection unit 200 includes a storage unit, a processor, etc. The storage unit includes main storage devices such as ROM and RAM, and / or auxiliary storage devices such as HDD and SSD. The processor is responsible for various processing tasks, including arithmetic units such as a CPU. The processor performs various functions by reading and executing computer programs stored in the storage unit.

[0032] The object detection unit 200 includes, as a functional structure, an input / output unit 201, a temperature sensor 202, a transceiver control unit 203, a transmitting circuit unit 204, a transceiver unit 205, a receiving circuit unit 206, a detection sensitivity adjustment unit 207, and a detection unit 208.

[0033] The input / output unit 201 is an interface for transmitting and receiving information with the ECU 100.

[0034] Temperature sensor 202 detects the ambient temperature (ambient air temperature) and outputs the detected temperature information to input / output unit 201.

[0035] When the transceiver control unit 203 receives a transmission instruction signal from the ECU 100 via the input / output unit 201, it outputs the transmission instruction signal to the transmission circuit unit 204. Additionally, it notifies the detection sensitivity adjustment unit 207 that a transmission instruction signal has been output.

[0036] When a transmission instruction signal is input from the transceiver control unit 203, the transmitting circuit unit 204 generates a pulse signal and outputs the pulse signal to the transceiver unit 205.

[0037] The transceiver unit 205 is driven by a pulse signal input from the transmitting circuit unit 204, transmitting ultrasonic waves and receiving reflected waves generated by the ultrasonic waves being reflected by an object. The transceiver unit 205 may have, for example, an oscillator composed of a piezoelectric element, which performs the transmission and reception of ultrasonic waves. Figure 2 In the example, an object O (obstacle) placed on the road surface RS is shown as an object that reflects the ultrasonic waves from the transceiver unit 205. The transceiver unit 205 outputs a received signal indicating the magnitude of the received reflected wave to the receiving circuit unit 206.

[0038] The receiving circuit section 206 receives a received signal from the transceiver section 205 and detects the signal level of the reflected wave received by the transceiver section 205. Specifically, for example, the receiving circuit section 206 amplifies and performs A / D conversion on the received signal received from the transceiver section 205 to generate a digital received signal, and outputs the digital received signal to the detection section 208. Furthermore, the receiving circuit section 206 includes a variable amplifier so that the receiving gain can be varied based on the sensitivity adjustment indication signal from the detection sensitivity adjustment section 207.

[0039] The detection sensitivity adjustment unit 207 adjusts the detection sensitivity of the receiving circuit unit 206 based on the second lowest temperature among the temperatures detected by the temperature sensors 202 of the multiple object detection units 200. For example, when the vehicle 1 meets preset driving conditions (average speed, driving time, etc.) based on the cooling effect of the ambient temperature caused by the driving wind, the detection sensitivity adjustment unit 207 adjusts the detection sensitivity of the receiving circuit unit 206 based on the second lowest temperature among the temperatures detected by the temperature sensors 202 of the multiple object detection units 200. The detection sensitivity adjustment unit 207 adjusts the detection sensitivity of the receiving circuit unit 206 based, for example, on table information that determines the relationship between temperature and reception gain, and the second lowest temperature.

[0040] Furthermore, the ECU 100 calculates vehicle speed information based on detection results from wheel speed sensors, acceleration sensors, and other sensors present in the vehicle 1, and sends this vehicle speed information to the object detection unit 200. Based on this vehicle speed information, the object detection unit 200 calculates the average vehicle speed and travel time, and determines whether the driving conditions are met.

[0041] The detection unit 208 detects an object by comparing the signal level detected by the receiving circuit unit 206 with a predetermined signal threshold. Specifically, the detection unit 208 detects an object by comparing the signal level represented by the digital received signal from the receiving circuit unit 206 with a predetermined signal threshold. Furthermore, the detection unit 208 calculates the distance to the object based on the time difference between transmitting the ultrasonic wave from the transceiver unit 205 and receiving the reflected wave. The detection unit 208 sends the detection result and calculation result to the ECU 100 via the input / output unit 201.

[0042] Figure 3 This is an exemplary and schematic flowchart illustrating a series of processes performed by the object detection unit 200 of the first embodiment.

[0043] First, in step S1, the input / output unit 201 acquires all the temperature information from the temperature sensors 202.

[0044] Next, in step S2, the detection sensitivity adjustment unit 207 obtains vehicle speed information from the ECU 100.

[0045] Next, in step S3, the detection sensitivity adjustment unit 207 calculates the average vehicle speed (e.g., the average vehicle speed over the last few minutes) based on the vehicle speed information.

[0046] Next, in step S4, the detection sensitivity adjustment unit 207 determines whether the average vehicle speed is above the vehicle speed threshold (whether the driving conditions are met). If yes, proceed to step S5; otherwise, proceed to step S7.

[0047] In step S5, the detection sensitivity adjustment unit 207 sets the second lowest temperature information among all temperature information as the parameter "sensor temperature".

[0048] Next, in step S6, the detection sensitivity adjustment unit 207 sets the sensor temperature to the "external temperature inferred value" of the parameter.

[0049] Furthermore, the external temperature inference value is first set when the engine starts, as the second lowest temperature among all temperature information, and then updated during the processing in step S6.

[0050] In step S7, the detection sensitivity adjustment unit 207 adjusts the detection sensitivity of the receiving circuit unit 206 based on the external temperature inferred value.

[0051] Thus, according to the object detection system of the first embodiment, by adjusting the detection sensitivity of the receiving circuit section 206 based on the second lowest temperature among the temperatures detected by the multiple temperature sensors 202, the object detection accuracy can be improved based on the possibility of malfunction of the temperature sensor 202.

[0052] That is, the probability of two or more temperature sensors 202 failing simultaneously is very low compared to the probability of one temperature sensor 202 failing. Therefore, even if the first lowest temperature is an abnormal value output from a faulty temperature sensor 202, the normal second lowest temperature can still be used. Therefore, by appropriately adjusting the sensitivity of the receiving circuit section 206, the detection distance for object detection can be extended, or the possibility of misdetecting road surfaces as objects can be reduced.

[0053] Furthermore, by adjusting the detection sensitivity of the receiving circuit section 206 under the aforementioned driving conditions, the object detection accuracy can be further improved by utilizing the driving wind generated by the vehicle's movement to cool the temperature sensors. That is, by utilizing the driving wind to cool the temperature sensor 202 and its surrounding components, which become hot due to engine exhaust heat, direct sunlight, etc., the sensitivity of the receiving circuit section 206 can be appropriately adjusted.

[0054] (Second Implementation)

[0055] Next, the second embodiment will be described. Details that are the same as in the first embodiment will be omitted from the description as appropriate. Figure 1 , Figure 2 Similar to the first embodiment, the temperature sensor 202 periodically detects the ambient temperature.

[0056] In addition, if the detection sensitivity adjustment unit 207 sets the second lowest temperature to the estimated external temperature value when the second lowest temperature is lower than the most recent estimated external temperature value.

[0057] In addition, if the second lowest temperature is higher than the most recent external temperature inferred value and lower than the value obtained by adding a predetermined temperature rise threshold to the most recent external temperature inferred value, the detection sensitivity adjustment unit 207 will set the value calculated using the second lowest temperature and the most recent external temperature inferred value based on a predetermined calculation formula as the external temperature inferred value.

[0058] In addition, if the second lowest temperature is a value obtained by adding a predetermined temperature rise threshold to the most recent external temperature, the detection sensitivity adjustment unit 207 sets the most recent external temperature as the external temperature inference value.

[0059] Furthermore, the detection sensitivity adjustment unit 207 adjusts the detection sensitivity of the receiving circuit unit 206 based on the latest external temperature inference value.

[0060] Figure 4 This is an exemplary and schematic flowchart illustrating a series of processes performed by the object detection unit in the second embodiment. Steps S1 to S5 and Figure 3 The situation is the same.

[0061] After step S5, in step S11, the detection sensitivity adjustment unit 207 determines whether the sensor temperature (second lowest temperature) is lower than the most recent external temperature inferred value. If yes, it proceeds to step S12; otherwise, it proceeds to step S13.

[0062] In step S12, the detection sensitivity adjustment unit 207 sets the sensor temperature to the "external temperature inferred value" of the parameter.

[0063] In step S13, the detection sensitivity adjustment unit 207 determines whether the sensor temperature (second lowest temperature) is lower than the value obtained by adding a predetermined temperature rise threshold to the most recent external temperature value. If yes, it proceeds to step S14; otherwise, it proceeds to step S15.

[0064] In step S14, the detection sensitivity adjustment unit 207 sets the average of the sensor temperature and the two most recent external temperature inference values ​​as the parameter "external temperature inference value".

[0065] In step S15, the detection sensitivity adjustment unit 207 sets the previous external temperature inference value as the "external temperature inference value" of the parameter. That is, the "external temperature inference value" of the parameter is not changed.

[0066] In step S16, the detection sensitivity adjustment unit 207 adjusts the detection sensitivity of the receiving circuit unit 206 based on the latest external temperature inference value.

[0067] Thus, according to the object detection system of the second embodiment, by comparing the second lowest temperature with the most recent external temperature estimate and the value obtained by adding a predetermined temperature rise threshold to the most recent external temperature estimate, the external temperature estimate can be set to a more appropriate value, thereby further improving the object detection accuracy.

[0068] Specifically, if the second lowest temperature is lower than the most recent external temperature estimation value, it is directly set as the external temperature estimation value. Alternatively, if the second lowest temperature is higher than the most recent external temperature estimation value but lower than the value obtained by adding a predetermined temperature rise threshold to the most recent external temperature estimation value, the temperature between the second lowest temperature and the most recent external temperature estimation value is set as the external temperature estimation value. Furthermore, if the second lowest temperature is higher than the value obtained by adding a predetermined temperature rise threshold to the most recent external temperature estimation value, it is not used due to high temperature, and the most recent external temperature estimation value is set as the external temperature estimation value. In this way, by setting the external temperature estimation value to a more appropriate value according to different situations, and adjusting the detection sensitivity of the receiving circuit unit 206 based on this external temperature estimation value, the object detection accuracy can be further improved.

[0069] Furthermore, while the external temperature inference value is set as the average of the sensor temperature and the two most recent external temperature inference values ​​in step S14, it is not limited to this. For example, it can also be set as the average of the sensor temperature and the most recent external temperature inference value, or as the average of the sensor temperature and the three or more most recent external temperature inference values. In addition, when averaging, a weighted average (e.g., the newer the information, the greater the weight) can also be performed.

[0070] While the embodiments and modifications of the present invention have been described above, these embodiments and modifications are merely examples and are not intended to limit the scope of the invention. The new embodiments and modifications described above can be implemented in various forms, and various omissions, substitutions, and changes can be made without departing from the spirit of the invention. The above embodiments and modifications are included within the scope and spirit of the invention, and are included within the scope of the invention described in the technical solution and its equivalents.

[0071] For example, ECU 100 can also perform part of the functions of object detection unit 200. Specifically, ECU 100 can also perform calculations such as average vehicle speed performed by detection sensitivity adjustment unit 207.

Claims

1. An object detection system, characterized in that, Equipped with multiple object detection units, The above-mentioned object detection unit has: The transceiver unit transmits ultrasonic waves and receives reflected waves generated by the ultrasonic waves being reflected by an object. The receiving circuit section detects the signal level of the reflected wave received by the transceiver section. The detection unit detects an object by comparing the signal level detected by the receiving circuit unit with a predetermined signal threshold. A temperature sensor that detects the temperature of the environment; as well as The detection sensitivity adjustment unit adjusts the detection sensitivity of the receiving circuit based on the second lowest temperature among the temperatures detected by the temperature sensors of the plurality of object detection units. The aforementioned object detection system is installed in the vehicle. The aforementioned detection sensitivity adjustment unit adjusts the detection sensitivity of the receiving circuit unit based on the second lowest temperature among the temperatures detected by the temperature sensors of the multiple object detection units, assuming that the vehicle meets the preset driving conditions based on the cooling effect of the ambient temperature caused by the driving wind. The aforementioned temperature sensor periodically detects the temperature of the aforementioned environment. When the aforementioned detection sensitivity adjustment unit is lower than the most recent estimated external temperature value, it sets the second lowest temperature as the estimated external temperature value. If the second lowest temperature is above but below the most recent external temperature estimate, obtained by adding a predetermined temperature rise threshold to the most recent external temperature estimate, then the value calculated using the second lowest temperature and the most recent external temperature estimate based on a predetermined formula shall be set as the external temperature estimate. If the second lowest temperature mentioned above is a value obtained by adding the most recent external temperature estimate to the aforementioned predetermined temperature rise threshold, then the most recent external temperature estimate shall be set as the external temperature estimate. The detection sensitivity of the receiving circuit is adjusted based on the latest external temperature inference value.

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