Moving body surroundings detection system

Abstract

The present invention provides a moving body surroundings detection system comprising an ultrasonic sensor for detecting an object in the surroundings of a moving body and a control circuit that analyzes a detection signal from the ultrasonic sensor. The ultrasonic sensor includes an excitation part having an effective radius set to no more than half the wavelength of the sound wave to be oscillated. The maximum detection distance in the horizontal direction with respect to the plane of the excitation part of the ultrasonic sensor is set longer than half the maximum height of the moving body from the ground and shorter than the maximum height of the moving body from the ground. The ultrasonic sensor is attached to the moving body at an angle such that the distance between the center of the excitation part and the intersection of the ground and a plane passing through the center of the excitation part and parallel to the excitation part is the maximum detection distance or less, and such that the distance between the center of the excitation part and the intersection of a plane parallel to the ground and passing through the position of the maximum height of the moving body from the ground and the plane passing through the center of the excitation part and parallel to the excitation part is the maximum detection distance or less.

Description

Mobile object surrounding detection system

[0001] The present disclosure relates to a mobile object surroundings detection system that detects the surroundings of a mobile object.

[0002] Ultrasonic sensors are used to monitor the periphery of moving objects such as automobiles, and various configurations and methods have been proposed (see Patent Documents 1 to 5). These ultrasonic sensors generally use bulk ceramic PZT, a piezoelectric material, as an actuator, and the excitation section is approximately 3 cm in diameter. However, ultrasonic sound sources of this size are inherently directional due to interference, which limits the ultrasonic sensor's field of view, resulting in limitations such as a narrow or inconsistent field of view. As a result, there have been challenges in detecting obstacles such as curbs and signs, whose bottom or top protrudes from the moving object.

[0003] Japanese Patent Application Laid-Open No. 2021-150872 Japanese Patent Application Laid-Open No. 2009-058362 Japanese Patent Application Laid-Open No. 2008-099049 Japanese Patent Application Laid-Open No. 61-186885 Japanese Utility Model Application Laid-Open No. 03-099383

[0004] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a mobile body surroundings detection system that can efficiently detect the surroundings of a mobile body using a simple method.

[0005] A mobile object surrounding detection system according to one disclosure includes an ultrasonic sensor for detecting objects around the mobile object and a control circuit for analyzing a detection signal from the ultrasonic sensor. The ultrasonic sensor includes an excitation unit whose effective radius is set to equal to or less than half the wavelength of the emitted sound waves. The maximum detection distance of the ultrasonic sensor in the horizontal direction relative to the surface of the excitation unit is set to be longer than half the maximum height of the mobile object from the ground and shorter than the maximum height of the mobile object from the ground. The ultrasonic sensor is attached to the mobile object at an angle such that the distance between the center of the excitation unit and an intersection line between the ground and a plane passing through the center of the excitation unit and a plane passing through the mobile object's maximum height from the ground and a plane passing through the center of the excitation unit and a plane parallel to the excitation unit is equal to or less than the maximum detection distance.

[0006] The mobile object surroundings detection system of the present disclosure is capable of detecting the surroundings of a mobile object in a simple manner.

[0007] FIG. 1 is a diagram illustrating a configuration of a mobile object periphery detection system according to a first embodiment. FIG. 1 is a diagram illustrating a configuration of an excitation unit 110 of an ultrasonic sensor 100 according to the first embodiment. FIG. 2 is a diagram illustrating directivity of an ultrasonic sensor 100 according to the first embodiment. FIG. 3 is a diagram illustrating a configuration of an ultrasonic sensor 100 according to the first embodiment. FIG. 4 is a diagram illustrating measurement of a distance to an object by an ultrasonic sensor 100 according to the first embodiment. FIG. 5 is a diagram illustrating measurement of a ground surface SL and a distance to an object by an ultrasonic sensor 100 according to the first embodiment. FIG. 6 is a diagram illustrating another example of an attachment position of an ultrasonic sensor 100 according to the first embodiment. FIG. 7 is a diagram illustrating an application example of a mobile object periphery detection system 1 according to the first embodiment. FIG. 8 is a diagram illustrating another application example of a mobile object periphery detection system 1 according to the first embodiment. FIG. 9 is a diagram illustrating detection of an obstacle when a plurality of ultrasonic sensors are provided according to a second embodiment. FIG. 10 is a flowchart illustrating operation of a control circuit 200 of a mobile object periphery detection system 1 according to the second embodiment. FIG. 11 is a diagram illustrating detection of the ground surface when a plurality of ultrasonic sensors are provided according to a third embodiment. FIG. 12 is a diagram illustrating a method of calculating an inclination of a vehicle 10 according to the third embodiment. FIG. 10 is a diagram illustrating the configuration of various devices provided in vehicle 10 according to embodiment 3. FIG. 11 is a diagram illustrating detection of the ground when a plurality of ultrasonic sensors are provided according to embodiment 4. FIG. 12 is a diagram illustrating an example of control of travel processing of vehicle 10A according to embodiment 4. FIG. 13 is a flow diagram illustrating operation of control circuit 200 of mobile object periphery detection system 1 according to embodiment 4. FIG. 14 is another diagram illustrating detection of the ground when a plurality of ultrasonic sensors are provided according to embodiment 4. FIG. 15 is a flow diagram illustrating another operation of control circuit 200 of mobile object periphery detection system 1 according to embodiment 4.

[0008] Hereinafter, embodiments will be described with reference to the accompanying drawings. In the following description, identical parts are designated by the same reference numerals. Since the names and functions of these parts are also the same, detailed description thereof will not be repeated.

[0009] Embodiment 1. FIG. 1 is a diagram illustrating the configuration of a mobile object periphery detection system according to Embodiment 1. Referring to FIG. 1(A), the mobile object periphery detection system 1 includes a vehicle 10, which is a mobile object, an ultrasonic sensor 100 for detecting objects around the mobile object, and a control circuit 200 for analyzing a detection signal from the ultrasonic sensor 100. The ultrasonic sensor 100 includes an excitation unit 110, which will be described later, and whose effective radius is set to less than half the wavelength of the emitted sound waves. The detection range AR of the ultrasonic sensor 100 is shown, and the detection range AR is represented by a semicircle having a radius of a maximum detection distance Lmax from the center of the excitation unit 110, which will be described later. Here, a plane PA parallel to the surface of the excitation unit 110 is shown. Also shown is a plane PL parallel to the ground GL on which the vehicle 10 is in contact. Also shown is a plane PH parallel to the ground GL that passes through the position of the vehicle 10 at its maximum height from the ground GL.

[0010] The maximum detection distance Lmax of the ultrasonic sensor 100 will now be described. The maximum detection distance Lmax in the horizontal direction relative to the plane of the excitation unit 110 of the ultrasonic sensor 100 is set to be longer than half the maximum height PH of the vehicle 10, which is a moving body, from the ground surface GL, and shorter than the maximum height of the vehicle 10, which is a moving body, from the ground surface GL.

[0011] The following describes the mounting position of the ultrasonic sensor 100. The ultrasonic sensor 100 is mounted on a vehicle 10, which is a moving body, at an angle such that the distance between the center of the excitation unit 110 and an intersection line CL between a plane PA, which passes through the center of the excitation unit 110 and is parallel to the excitation unit 110, and the ground GL, is equal to or less than the maximum detection distance Lmax, and the distance between the center of the excitation unit 110 and an intersection line CH between a plane PH, which passes through the center of the excitation unit 110 and is parallel to the ground GL and is at the maximum height from the ground of the vehicle 10, which is a moving body, is equal to or less than the maximum detection distance Lmax.

[0012] In this example, for the vehicle 10, the distance between the center of the excitation unit 110 and the intersection line CL between the ground GL and a plane PA that passes through the center of the excitation unit 110 and is parallel to the excitation unit 110 is indicated as a distance DL.

[0013] In this example, for vehicle 10, the distance between the intersection line CH of a plane PA that passes through the center of excitation unit 110 and is parallel to excitation unit 110 and a plane PH that passes through the maximum height from the ground of vehicle 10, which is a moving body parallel to the ground GL, and the center of excitation unit 110 is shown as distance DH.

[0014] With this arrangement, the ultrasonic sensor 100 attached to the vehicle 10 has a detection range that is the area where the sensor 100 is in contact with the ground, and also has a detection range that is the area at the maximum height position of the vehicle 10 .

[0015] This detection range makes it possible to detect the surroundings of the vehicle 10 in a simple manner without installing multiple ultrasonic sensors 100, and makes it possible to efficiently detect the surroundings of the vehicle 10, which is a moving body.

[0016] Using only the ultrasonic sensor 100, it is possible to comprehensively detect obstacles that only protrude partially (for example, signs attached to an overhang) and obstacles that exist only near the road surface (for example, curbs on the road) at close range. As a result, when pulling up to a wall or obstacle or parking in a narrow parking space, it is possible to approach the obstacle within a short distance without hitting it.

[0017] In this example, the detection range AR includes the ground GL. The ultrasonic sensor 100 outputs a signal corresponding to the distance of the ground GL included in the detection range AR to the control circuit 200. The control circuit 200 continuously receives a detection signal corresponding to the distance from the ground GL from the ultrasonic sensor 100. When detecting an obstacle other than the ground GL, the control circuit 200 executes a process of excluding detection signals indicating a predetermined distance from the analysis target for a predetermined period of time or more. This enables the control circuit 200 to detect obstacles other than the ground GL. On the other hand, when detecting the ground GL, the control circuit 200 receives a detection signal indicating a predetermined distance from the ultrasonic sensor 100 for a predetermined period of time or more. This enables the control circuit 200 to determine that the detection signal is the ground GL and detect the distance to the ground GL.

[0018] Referring to FIG. 1B , the mobile object periphery detection system 1 includes a vehicle 10, which is a mobile object, an ultrasonic sensor 100 for detecting objects around the mobile object, and a control circuit 200 for analyzing the detection signal of the ultrasonic sensor 100. The ultrasonic sensor 100 includes an excitation unit 110, described below, whose effective radius is set to less than half the wavelength of the emitted sound waves. The detection range AR of the ultrasonic sensor 100 is shown, and the detection range AR is represented as a semicircle with a radius of a maximum detection distance Lmax from the center of the excitation unit 110, described below. A plane PA parallel to the surface of the excitation unit 110 is also shown. A plane PL parallel to the ground GL on which the vehicle 10 is in contact is also shown. A plane PH parallel to the ground GL passing through the position of the vehicle 10 at its maximum height from the ground GL is also shown.

[0019] The following describes the mounting position of the ultrasonic sensor 100. The ultrasonic sensor 100 is mounted on a vehicle 10, which is a moving body, at an angle such that the distance between the center of the excitation unit 110 and an intersection line CL between a plane PA, which passes through the center of the excitation unit 110 and is parallel to the excitation unit 110, and the ground GL, is equal to or less than the maximum detection distance Lmax, and the distance between the center of the excitation unit 110 and an intersection line CH between a plane PH, which passes through the center of the excitation unit 110 and is parallel to the ground GL and is at the maximum height from the ground of the vehicle 10, which is a moving body, is equal to or less than the maximum detection distance Lmax.

[0020] At this point, a plane PA that passes through the center of the excitation unit 110 and is parallel to the excitation unit 110 is set to be approximately perpendicular to the ground GL. Note that "approximately perpendicular" does not have to be completely perpendicular, and also includes a state close to perpendicular.

[0021] With this arrangement, the ultrasonic sensor 100 attached to the vehicle 10 has a detection range that is the area where the sensor 100 contacts the ground and also the range at the maximum height of the vehicle 10. By extending the detection range to near the feet of the vehicle 10, it becomes possible to eliminate blind spots and detect obstacles. This detection range makes it possible to detect the periphery of the vehicle 10 in a simple manner without installing multiple ultrasonic sensors 100, and to efficiently detect the periphery of the vehicle 10, which is a moving body.

[0022] 2A and 2B are diagrams illustrating the configuration of the excitation unit 110 of the ultrasonic sensor 100 according to the first embodiment. Referring to FIG. 2A, the excitation unit 110 includes an upper electrode 111, a piezoelectric body 112, and a lower electrode 113. The upper electrode 111, the piezoelectric body 112, and the lower electrode 113 form a piezoelectric element. Furthermore, the excitation unit 110 includes a sealant 114 for sealing the piezoelectric element and an aluminum housing 115. The upper electrode 111 and the lower electrode 113 are made of silver (Ag). The piezoelectric body 112 is made of PZT (PbZrxTi1-xO3). The housing 115 is made of silicone.

[0023] Referring to FIG. 2B , the excitation unit 110A includes an upper electrode 111A, a piezoelectric body 112A, and a lower electrode 113A. The upper electrode 111A, the piezoelectric body 112A, and the lower electrode 113A form a piezoelectric element. The upper electrode 111A and the lower electrode 113A are made of platinum (Pt). The piezoelectric body 112A is made of PZT (PbZrxTi1-xO3). The housing 115 is made of silicone. The ultrasonic sensor 100 is produced using MEMS (microelectromechanical system) processing techniques, including deep reactive ion etching (DRIE) and anisotropic etching. When a voltage is applied between the electrodes, the piezoelectric body expands and contracts, vibrating the excitation units 110 and 110A and generating acoustic waves. Conversely, the ultrasonic sensor 100 also functions as a receiving element by converting the vibration of the excitation units 110 and 110A caused by acoustic waves into a voltage signal. The detection distance is set based on the transmitted sound pressure from the excitation unit 110 of the ultrasonic sensor 100, the receiving sensitivity, and noise.

[0024] 3 is a diagram illustrating the directivity of ultrasonic sensor 100 according to the first embodiment. Referring to FIG. 3, in a moving object periphery detection system using ultrasonic sensor 100, an effective radius a of the excitation part of the ultrasonic sensor is eff (a eff =√3 / 3*a, where a: actual radius of the excitation unit) is set to be equal to or less than half the wavelength of the sound waves oscillated by the excitation units 110 and 110A.

[0025] The directivity of the excitation sections 110 and 110A is approximately expressed by the following equation using the fraction k, the fraction k of the excitation section, and the excitation sections 110 and 110A.

[0026]

[0027] J1: First-order Bessel function In this example, the directivity is shown for a frequency of 58 kHz, a sound speed of 347 m / s (k = 1051 / m), an effective radius of the excitation unit of 500 μm, and λ / 4, λ / 2, λ, and 5λ / 4. The sound pressure is normalized by the magnitude at angle 0, where the sound pressure is greatest. As shown in this figure, when the effective radius of the excitation unit is less than half the wavelength of the generated sound wave, it can be seen that within a field of view angle of ±90°, the waves do not completely cancel each other out due to interference.

[0028] When the effective radius of the excitation section is less than half the wavelength of the generated sound waves, the waves do not completely cancel each other out due to interference within the viewing angle range of ±90°, making it possible to increase the viewing angle.

[0029] Therefore, as explained above, by arranging the ultrasonic sensor 100 on the moving body, the vehicle 10, so that it can detect both the ground in the planar direction of the excitation unit 110 and the obstacle at the highest position on the moving body, the vehicle 10, it becomes possible to detect obstacles up to a position close to the moving body, up to a height from the road surface to the top surface of the moving body.

[0030] 4 is a diagram illustrating the configuration of ultrasonic sensor 100 according to embodiment 1. Referring to FIG. 4, ultrasonic sensor 100 includes an excitation unit 110, a drive unit 102, a signal processing unit 104, a power supply unit 106, a signal output unit 108, and a storage unit 109.

[0031] The driving unit 102 drives the excitation unit 110 to generate sound waves. The signal processing unit 104 converts the vibrations of the excitation unit 110 into a voltage signal. The power supply unit 106 supplies the necessary voltage to each unit within the ultrasonic sensor 100. The memory unit 109 functions as a working memory and stores data such as various parameters required for the operation of the ultrasonic sensor 100. The signal output unit 108 outputs the detection signal processed by the signal processing unit 104 to the outside. In this example, the ultrasonic sensor 100 is connected to a control circuit 200, and the signal output unit 108 of the ultrasonic sensor 100 outputs the converted detection signal to the control circuit 200. The control circuit 200 executes an analysis process to analyze the detection signal from the ultrasonic sensor 100.

[0032] 5A and 5B are diagrams illustrating measurement of the distance to an object by ultrasonic sensor 100 according to embodiment 1. Referring to Fig. 5A, a formula for calculating the distance from ultrasonic sensor 100 to an object is shown.

[0033]

[0034] Referring to FIG. 5B, at time t T5C, the excitation unit 110 is driven to output ultrasonic waves of a predetermined intensity from the ultrasonic sensor 100. R At the signal threshold S t 1 shows a case where the excitation unit 110 detects a reflected wave with a signal level exceeding the signal threshold S t The level can be adjusted to any level.

[0035] The signal processing unit 104 outputs the sensor-to-object distance d based on the above equation as a detection signal to the control circuit 200. This enables the control circuit 200 to recognize that an object is present at the sensor-to-object distance d.

[0036] 6A and 6B are diagrams illustrating measurement of the distance to the ground surface SL and the object by ultrasonic sensor 100 according to embodiment 1. Referring to Fig. 6A, equations for calculating the distance from ultrasonic sensor 100 to the ground surface SL and the object are shown.

[0037] Referring to FIG. 6B, at time t T 6C, the excitation unit 110 is driven to output ultrasonic waves of a predetermined intensity from the ultrasonic sensor 100. Referring to FIG. 6C, the ultrasonic waves reflected from the ground GL at time t R1 At the signal threshold S t 1. The excitation unit 110 detects a reflected wave with a signal level exceeding t R2 At the signal threshold S t 1 shows a case where the excitation unit 110 detects a reflected wave with a signal level exceeding the signal threshold S t The level can be adjusted to any level.

[0038] For example, the signal processing unit 104 outputs the sensor-to-target distance d based on the above equation as a detection signal to the control circuit 200. In this example, two detection signals are output to the control circuit 200: one indicating the distance between the ultrasonic sensor 100 and the ground GL, and the other indicating the distance between the ultrasonic sensor 100 and the target. The control circuit 200 can execute processing to determine that a detection signal indicating a predetermined distance from the ultrasonic sensor 100 for a predetermined period of time or longer is the ground and exclude it from analysis. The control circuit 200 can then recognize that an target is present at the sensor-to-target distance d.

[0039] FIG. 7 is a diagram illustrating another example of the mounting position of ultrasonic sensor 100 according to the first embodiment. Referring to FIG. 5 , in this example, ultrasonic sensor 100 is mounted at a position where a surface parallel to excitation unit 110 of ultrasonic sensor 100 is in contact with a portion of vehicle 10, which is a moving body. Specifically, ultrasonic sensor 100 is disposed in such a manner that a surface parallel to excitation unit 110 of ultrasonic sensor 100 is in contact with a portion of the body of vehicle 10. This configuration can minimize blind spots near vehicle 10, which is a moving body. This configuration can be applied when there are limitations on the mounting position of the sensor and a blind spot is created near the moving body due to a portion protruding from the moving body, such as a bumper. Note that the terms "parallel" and "in contact" refer to a design arrangement and are concepts that include not only completely parallel and in contact, but also parallel and in contact within a tolerance range.

[0040] FIG. 8 is a diagram illustrating an application example of the mobile object periphery detection system 1 according to the first embodiment. Referring to FIG. 8A, a case in which the ultrasonic sensor 100 is provided at the rear of the vehicle 10 as described in FIG. 7 will be described. In this example, for example, if an obstacle is present on the ceiling other than the ground, it is possible to detect the obstacle even if the obstacle interferes with the highest point of the vehicle 10. For example, by outputting a detection sound when an obstacle is detected, it is possible to avoid interference with the obstacle. Referring to FIG. 8B, a case in which the ultrasonic sensor 100 is provided at the rear of the vehicle 10 as described in FIG. 7 will be described. In this example, for example, if an obstacle is present protruding from the ground, it is possible to detect the obstacle even if the obstacle interferes with the lower part of the vehicle 10. For example, by outputting a detection sound when an obstacle is detected, it is possible to avoid interference with the obstacle. This detection range makes it possible to detect the periphery of the vehicle 10 in a simple manner without providing multiple ultrasonic sensors 100, thereby enabling efficient detection of the periphery of the vehicle 10, which is a mobile object.

[0041] 9 is a diagram illustrating another application example of the mobile object periphery detection system 1 according to the first embodiment. Referring to FIG. 9A, a case will be described in which the ultrasonic sensor 100 is provided on the side of the vehicle 10 as described in FIG. 1. In this example, therefore, even obstacles that protrude only partially (such as signs attached by an overhang or bicycle handlebars) can be comprehensively detected up to a short distance. This makes it possible to approach a mobile object close to a wall or obstacle without hitting the obstacle, for example, when pulling up to the wall or obstacle or parking in a narrow parking space.

[0042] As described above, the control circuit 200 executes a process of determining that a detection signal from the ultrasonic sensor 100 indicating a predetermined distance for a predetermined period of time or longer is the ground and excluding it from the analysis target.

[0043] 9B, a case where the ultrasonic sensor 100 is provided on the side of the vehicle 10 as described in FIG. 1 will be described. In this example, for example, obstacles that exist only near the road surface (e.g., road curbs) can be comprehensively detected up to a short distance. Therefore, when a moving body is pulled up to a wall or obstacle or parked in a narrow parking space, the moving body can approach the obstacle within a short distance without hitting it. This detection range makes it possible to detect the periphery of the vehicle 10 in a simple manner without providing multiple ultrasonic sensors 100, and it is possible to efficiently detect the periphery of the moving body, the vehicle 10.

[0044] Second Embodiment In the first embodiment described above, a configuration capable of detecting an obstacle included in the detection range of the ultrasonic sensor 100 has been described.

[0045] On the other hand, a single ultrasonic sensor 100 cannot detect the position of an obstacle within the detection range.

[0046] In the second embodiment, a method of detecting the position of an obstacle by providing a plurality of ultrasonic sensors 100 will be described.

[0047] 10 is a diagram illustrating obstacle detection when a plurality of ultrasonic sensors are provided according to the second embodiment. Referring to FIG. 10, a case where ultrasonic sensors 100A and 100B are provided is shown. Here, the distance between ultrasonic sensors 100A and 100B is distance Qd.

[0048] Here, the ultrasonic sensor 100A detects a distance QLa from the detection target, and the ultrasonic sensor 100B detects a distance QLb from the detection target.

[0049] The distances QLa and QLb are expressed by the following equations.

[0050]

[0051] The distances Qh and QL are expressed by the following equations.

[0052]

[0053] Therefore, based on this equation, it is possible to calculate the distances Qh and QL and calculate the position. Specifically, it is possible to calculate the position of the detection target from the angle tan θ=Qh / QL.

[0054] FIG. 11 is a diagram illustrating an application example of the mobile object periphery detection system 1 according to the second embodiment. Referring to FIG. 11A, a case will be described in which ultrasonic sensors 100A and 100B are provided vertically on the rear side of the vehicle 10 as described in FIG. 5. In this example, for example, when the vehicle 10 is moving forward, the ultrasonic sensors 100A and 100B detect obstacles other than the ground throughout the entire detection range AR. Referring to FIG. 11B, a case will be described in which ultrasonic sensors 100A and 100B are provided vertically on the rear side of the vehicle 10 as described in FIG. 5. In this example, for example, when the vehicle 10 is moving backward, the ultrasonic sensors 100 detect obstacles within a predetermined range rather than the entire detection range AR.

[0055] Specifically, the control circuit 200 calculates the position of the obstacle based on the detection signals from the ultrasonic sensors 100A and 100B in accordance with the above-described calculation formula. For example, the control circuit 200 detects obstacles of a predetermined height or higher in the lower region of the detection range AR. In other words, objects below the predetermined height, such as wheel chocks, are not detected as obstacles.

[0056] FIG. 12 is a flowchart illustrating the operation of control circuit 200 of moving object periphery detection system 1 according to the second embodiment.

[0057] The control circuit 200 determines whether the vehicle 10 is moving forward (step S1). Specifically, the control circuit 200 determines whether the vehicle 10 is moving forward based on information obtained from the vehicle 10. For example, the control circuit 200 may determine whether the vehicle 10 is moving forward using an acceleration sensor, or may determine whether the vehicle 10 is moving forward using internal information of the vehicle 10.

[0058] If the control circuit 200 determines in step S1 that the vehicle 10 is moving forward, it determines whether or not there is an abnormality in the normal range of the detection range AR (step S2).

[0059] In step S2, if the control circuit 200 determines that an abnormality exists in the normal range of the detection range AR (YES in step S2), it executes a notification process (step S3). Specifically, the notification process may involve outputting an abnormal sound or the like using a speaker (not shown). Alternatively, a message indicating the existence of an abnormality may be output using a display (not shown).

[0060] On the other hand, if the control circuit 200 determines in step S2 that there is no abnormality in the normal range of the detection range AR (NO in step S2), it skips step S3 and proceeds to step S4.

[0061] Next, the control circuit 200 determines whether the detection process has ended (step S4). For example, the control circuit 200 may determine that the detection process has ended when the vehicle 10 stops or when the power supply to the vehicle 10 is cut off.

[0062] In step S4, if the control circuit 200 determines that the detection process has ended (YES in step S4), the control circuit 200 ends the process (END).

[0063] On the other hand, in step S4, if control circuit 200 determines that the detection process has not ended (NO in step S4), it returns to step S1 and repeats the above process.

[0064] On the other hand, in step S1, if the control circuit 200 determines that the vehicle 10 is not moving forward (NO in step S1), that is, if the vehicle 10 is moving backward, it determines whether there is an abnormality in a predetermined range in the detection range AR (step S5).

[0065] In step S5, if the control circuit 200 determines that an abnormality exists within a predetermined range of the detection range AR (YES in step S5), it executes a notification process (step S6). Specifically, the notification process may involve outputting an abnormal sound or the like using a speaker (not shown). Alternatively, a message indicating the existence of an abnormality may be output using a display (not shown).

[0066] On the other hand, in step S5, if control circuit 200 determines that there is no abnormality in the predetermined range of detection range AR (NO in step S5), it skips step S6 and proceeds to step S4.

[0067] This method makes it possible to prevent objects of less than a predetermined height, such as wheel chocks, from being detected as obstacles when the vehicle 10 is moving backward. This makes it possible to execute a stopping operation for the vehicle 10 without detecting an abnormality in the wheel chocks. This makes it possible to detect the surroundings of the vehicle 10 using a simple method, and to efficiently detect the surroundings of the vehicle 10, which is a moving object.

[0068] Embodiment 3 In the above-described embodiment 2, a method for detecting the position of an obstacle was described using a plurality of ultrasonic sensors 100. In this example, a method for detecting the inclination of a vehicle 10 using a plurality of ultrasonic sensors 100 will be described.

[0069] 13A and 13B are diagrams illustrating ground detection when a plurality of ultrasonic sensors are provided according to the third embodiment. Referring to Fig. 13A, ultrasonic sensors 100F and 100R are provided at the front and rear of a vehicle 10. Here, ultrasonic sensors 100F and 100R each detect the distance to the ground below vehicle 10.

[0070] The control circuit 200 determines that a detection signal indicating a predetermined distance from the ultrasonic sensors 100F, 100R for a predetermined period of time or longer indicates the ground, and detects the distance to the ground based on the detection signal.

[0071] In this example, the vehicle 10 is shown to be horizontal to the ground. The vehicle 10 is provided with four wheels, one each at the front, rear, left, and right, and each wheel is provided with a suspender (suspension device) (not shown). Therefore, when there is an object, such as a person, at the rear of the vehicle 10, the rear of the vehicle 10 will sink relative to the front via the suspender (suspension device).

[0072] Referring to FIG. 13B, this example shows a case where the ground and the vehicle 10 are not in a horizontal relationship, and the rear of the vehicle 10 is submerged.

[0073] 14 is a diagram illustrating a method for calculating the inclination of vehicle 10 according to embodiment 3. Referring to FIG. 14, ultrasonic sensors 100F and 100R detect distances L1 and L2, respectively, from the bottom of vehicle 10 to the ground.

[0074] The vehicle tilt θq can be calculated based on the distances L1 and L2 and the body length L3 of the vehicle 10 using the following formula:

[0075]

[0076] Fig. 15 is a diagram illustrating the configuration of various devices provided in vehicle 10 according to embodiment 3. Referring to Fig. 15, vehicle 10 is provided with lighting device 300, lighting control device 302, control circuit 200, and ultrasonic sensors 100F and 100R.

[0077] The lighting control device 302 controls the lighting device 300. Specifically, if the lighting device 300 is a headlight, for example, the lighting control device 302 controls the optical axis of the headlight. In this example, the lighting control device 302 controls the optical axis of the lighting device 300 based on the inclination of the vehicle body calculated by the control circuit 200. Specifically, the lighting control device 302 may correct the optical axis of the lighting device 300 so that it is parallel to the ground based on the inclination θq of the vehicle body calculated by the control circuit 200.

[0078] Therefore, based on this equation, it is possible to correct the optical axis of the lighting device 300 based on, for example, the inclination θq of the vehicle body. Specifically, it is possible to calculate the inclination θq of the vehicle body by detecting the distance to the ground GL detected by the ultrasonic sensors 100F, 100R.

[0079] In this example, the ultrasonic sensors 100F, 100R are provided in the longitudinal direction of the vehicle 10, but it is also possible to calculate the lateral tilt of the vehicle 10 by providing ultrasonic sensors 100 on the left and right sides of the vehicle 10. The lighting control device 302 can also correct the optical axis of the lighting device 300 based on the lateral tilt of the vehicle 10.

[0080] Furthermore, ultrasonic sensors 100 may be provided in the front-rear and left-right directions of the vehicle 10. The control circuit 200 calculates the tilt of the vehicle 10 in the front-rear and left-right directions and outputs the calculation results to the lighting control device 302. The lighting control device 302 may correct the optical axis of the lighting device 300 to be parallel to the ground based on the tilt in the front-rear and left-right directions.

[0081] Fourth Embodiment In the third embodiment described above, a method for detecting the state of the vehicle 10 by providing a plurality of ultrasonic sensors 100 has been described, but in this example, a method for detecting the inclination of the ground surface GL by using a plurality of ultrasonic sensors 100 will be described.

[0082] FIG. 16 is a diagram illustrating ground detection when multiple ultrasonic sensors are provided according to the fourth embodiment. Referring to FIG. 16, ultrasonic sensors 100F and 100R are provided at the front and rear of a vehicle 10A. The vehicle 10A is, for example, an unmanned vehicle, and is equipped with four wheels (front, rear, left, and right). Unlike the vehicle 10, the vehicle 10A does not have suspenders (suspension devices) for each wheel. Therefore, it is assumed that the vehicle 10A and the ground GL can basically maintain a horizontal relationship. Here, the ultrasonic sensors 100F and 100R each detect the distance from the ground below the vehicle 10.

[0083] Specifically, the control circuit 200 of the vehicle 10A shows a case where the ultrasonic sensors 100F and 100R detect distances L1 and L2 from the ground below the vehicle 10, respectively.

[0084] The ground inclination θr can be calculated based on the distances L1 and L2 and the horizontal distance L4 between the wheels of the vehicle 10A and the ultrasonic sensor 100F using the following formula:

[0085]

[0086] Vehicle 10A controls the traveling process based on the calculated ground gradient θr. Figure 17 is a diagram illustrating an example of the control of the traveling process of vehicle 10A according to the fourth embodiment. Referring to Figure 17(A), this example shows a case where there is a slope ahead of vehicle 10A. Vehicle 10A calculates the ground gradient θr, and continues traveling if the slope is acceptable.

[0087] 17B, ​​this example shows a case where there is a situation in front of the vehicle 10A where it is impossible to proceed, such as a step. The vehicle 10A calculates the inclination θr of the ground, and stops proceeding if there is a situation such as a step where it is impossible to proceed.

[0088] 18 is a flow diagram illustrating the operation of control circuit 200 of moving body periphery detection system 1 according to embodiment 4. In this example, the traveling process operation of vehicle 10A will be described.

[0089] 18, control circuit 200 calculates the inclination (step S10). Specifically, control circuit 200 calculates the inclination θr of the ground based on the distance and the like obtained from ultrasonic sensors 100F, 100R.

[0090] Next, the control circuit 200 determines whether the tilt is within a predetermined angle (step S12).

[0091] In step S12, if control circuit 200 determines that the inclination is within the predetermined angle (YES in step S12), it continues processing without stopping the movement.

[0092] Next, the control circuit 200 determines whether the progress processing has ended (step S14). For example, the control circuit 200 may determine that the progress processing has ended when the vehicle 10A stops or the power supply of the vehicle 10A is cut off.

[0093] In step S14, if the control circuit 200 determines that the progress process has ended (YES in step S14), the control circuit 200 ends the process (END).

[0094] On the other hand, if control circuit 200 determines in step S14 that the processing has not ended (NO in step S14), control circuit 200 returns to step S10 and repeats the above processing.

[0095] On the other hand, if the control circuit 200 determines in step S12 that the tilt is not within the predetermined angle (NO in step S12), it executes a stop process (step S16), and then ends the process (END).

[0096] This method allows the vehicle 10A, for example, to detect the surrounding conditions and stop moving forward if it is difficult to move forward. In other words, it is possible to detect the surroundings of the vehicle 10A in a simple manner and take appropriate action based on the detection results.

[0097] FIG. 19 is another diagram illustrating ground detection when multiple ultrasonic sensors are provided according to the fourth embodiment. Referring to FIG. 19 , ultrasonic sensors 100F and 100R are provided corresponding to the front, rear, left, and right sides of a drone 10B. The drone 10B is, for example, an unmanned drone searching for a landing site. Here, the ultrasonic sensors 100F and 100R each detect the distance from the bottom of the vehicle 10 to the ground.

[0098] Specifically, the ultrasonic sensors 100F and 100R of the drone 10B each detect the distance to the ground below the drone 10B.

[0099] Based on the distance detected by the ultrasonic sensors 100F and 100R, it is possible to calculate the slope of the ground where the aircraft is scheduled to land, using a method similar to that described above.

[0100] The drone 10B executes control of the landing process based on the calculated inclination of the ground. Fig. 20 is a flow diagram illustrating another operation of the control circuit 200 of the mobile object periphery detection system 1 according to the fourth embodiment. In this example, the landing process operation of the drone 10B will be described.

[0101] 20, the control circuit 200 calculates the inclination (step S20). Specifically, the control circuit 200 calculates the inclination θr of the ground based on the distance and the like obtained from the ultrasonic sensors 100F, 100R.

[0102] Next, the control circuit 200 determines whether the tilt is within a predetermined angle (step S22).

[0103] In step S22, if the control circuit 200 determines that the tilt is within the predetermined angle (YES in step S22), it continues the landing process.

[0104] Next, the control circuit 200 determines whether the processing has ended (step S24). For example, the control circuit 200 may determine that the landing processing has ended when the drone 10B has landed.

[0105] In step S24, if the control circuit 200 determines that the processing has ended (YES in step S14), the processing ends (END).

[0106] On the other hand, if control circuit 200 determines in step S24 that the process is not to be completed (NO in step S14), control circuit 200 returns to step S20 and repeats the above process.

[0107] On the other hand, if the control circuit 200 determines in step S12 that the tilt is not within the predetermined angle (NO in step S22), it executes landing stop processing (step S28), and then ends the processing (END).

[0108] For example, as a landing stop process, the aircraft may be evacuated to another location and the landing process may be executed at the evacuated location.

[0109] This method allows the drone 10B, for example, to detect the surrounding conditions and stop landing if the slope of the ground makes landing difficult. In other words, it is possible to detect the surroundings of the drone 10B in a simple manner and take appropriate action based on the detection results.

[0110] The configurations exemplified as the above-described embodiments are examples of the configurations of the present disclosure, and may be combined with other known technologies, or may be modified, such as by omitting some parts, within the scope of the gist of the present disclosure. Furthermore, the above-described embodiments may be implemented by appropriately adopting the processes and configurations described in other embodiments.

[0111] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present disclosure is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims.

[0112] 1 Mobile object surrounding detection system, 10, 10A vehicle, 10B drone, 100, 100A, 100B, 100F, 100R ultrasonic sensor, 102 drive unit, 104 signal processing unit, 106 power supply unit, 108 signal output unit, 109 memory unit, 110, 110A excitation unit, 111, 111A upper electrode, 112, 112A piezoelectric body, 113, 113A lower electrode, 114 sealing material, 115 housing, 200 control circuit, 300 lighting device, 302 lighting control device.

Claims

1. A mobile body surroundings detection system comprising: an ultrasonic sensor for detecting objects in the vicinity of a mobile body; and a control circuit for analyzing the detection signal of the ultrasonic sensor; the ultrasonic sensor includes an excitation unit whose effective radius is set to be equal to or less than half the wavelength of the sound waves emitted; the maximum detection distance of the ultrasonic sensor in the horizontal direction relative to the surface of the excitation unit is set to be longer than half the maximum height of the mobile body from the ground and shorter than the maximum height of the mobile body from the ground; the ultrasonic sensor is attached to the mobile body at an angle such that the distance between the center of the excitation unit and an intersection of the ground and a plane parallel to the excitation unit that passes through the center of the excitation unit is equal to or less than the maximum detection distance, and the distance between the center of the excitation unit and an intersection of a plane that is parallel to the ground and passes through the position of the mobile body's maximum height from the ground and a plane that passes through the center of the excitation unit and is parallel to the excitation unit is equal to or less than the maximum detection distance.

2. A mobile object surroundings detection system according to claim 1, wherein the ultrasonic sensor is mounted at an angle such that the surface of the excitation part is approximately perpendicular to the ground.

3. A mobile object surroundings detection system according to claim 1, wherein the surface parallel to the excitation unit is attached at a position where it contacts a part of the mobile object.

4. The mobile object surroundings detection system according to claim 1, wherein the ultrasonic sensor is produced using MEMS (Micro Electro Mechanical System) processing techniques including DRIE (Deep Reactive Ion Etching) and anisotropic etching.

5. A mobile object surroundings detection system as described in claim 1, wherein the control circuit excludes from analysis detection signals from the ultrasonic sensor that indicate a predetermined distance for a predetermined period of time or more.

6. A mobile body surroundings detection system as described in claim 1, wherein the mobile body includes a plurality of wheels and a plurality of suspension devices respectively corresponding to the plurality of wheels, a plurality of ultrasonic sensors are provided respectively corresponding to the forward and backward directions of the mobile body, and the control circuit measures the distance from the plurality of ultrasonic sensors to the ground, and calculates the inclination of the mobile body relative to the forward / backward direction and the ground based on the measurement results.

7. A mobile body surroundings detection system as described in claim 1, wherein the mobile body includes a plurality of wheels and a plurality of suspension devices respectively corresponding to the plurality of wheels, a plurality of ultrasonic sensors are provided respectively corresponding to the left and right directions of the mobile body, and the control circuit measures the distance from the plurality of ultrasonic sensors to the ground, and calculates the left and right directions of the mobile body and the inclination of the mobile body relative to the ground based on the measurement results.

8. A mobile object periphery detection system as described in claim 6 or 7, comprising: a lighting device provided on the mobile object; and a lighting control device that controls the direction of the lighting device, wherein the lighting control device corrects the direction of the lighting device based on the tilt calculated by the control circuit.

9. A mobile object surroundings detection system as described in claim 1, wherein a plurality of ultrasonic sensors are provided corresponding to the forward and backward directions of the mobile object, and the control circuit measures the distances from the plurality of ultrasonic sensors to the ground, and calculates the inclination of the ground around the mobile object based on the measurement results.

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