Object detection device

Abstract

To provide an object detection device which is modified so as to be capable of estimating positions of two objects even when the strength of indirect waves which are reflected waves of waves having been simultaneously transmitted by two sonars and reflected by objects is intensified in a state where two objects to be detected exist.SOLUTION: Provided is an object detection device in which, among sonars A to C disposed in an outer circumferential section of a vehicle 102 while spaced apart from each other, the sonars A and C transmit sound waves simultaneously and receive direct waves reflected by objects, and the sonar B receives an indirect wave reflected by an object. In a state where the sonars A and C receive direct waves and the sonar B receives an indirect wave, positions of objects present in a detection range of each of the sonars A and C are estimated on the basis of a flight time of the direct waves received by the sonars A and C and a flight time of the indirect wave received by the sonar B when a peak value of the indirect wave received by the sonar B is greater than or equal to a predetermined magnification Yamax with respect to peak values of the direct waves received by the sonars A and C.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to an object detection device for a vehicle such as an automobile. [Background technology]

[0002] An object detection device for a vehicle such as an automobile includes at least two sonars and a control unit that controls the sonars. A direct wave, which is an ultrasonic wave transmitted by one sonar and reflected by an object, is received by one sonar, and an indirect wave, which is an ultrasonic wave reflected by the object, is received by the other sonar. The control unit estimates the position of the object that reflected the direct wave and the indirect wave, i.e., the distance between the object and the vehicle and the direction of the object relative to the vehicle, based on the flight times of the direct wave and the indirect wave.

[0003] When multiple reflected waves are generated by an object and the multiple reflected waves overlap with each other due to phase shifts, the reflected waves cancel each other out, lowering the peak value of the indirect wave and making it impossible to detect the object. For example, the following Patent Document 1 describes an object detection device that addresses this problem, in which ultrasonic waves encoded by frequency modulation and pulse compression processing are used to improve the code identification performance of the reflected wave. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2022-124823 A Summary of the Invention

[0005] [Problem to be solved by the invention] In order to widen the object detection range and increase the object detection efficiency, it is possible to provide at least three sonars, with two sonars simultaneously transmitting ultrasonic waves and receiving direct waves while the remaining sonar receives indirect waves.

[0006] However, when the flight times of the two ultrasonic waves transmitted by the two sonars and received by the remaining sonar are the same and the phases of the two indirect waves when received by the remaining sonar are in phase or close to in phase, the two indirect waves reinforce each other. Therefore, the indirect wave received by the remaining sonar becomes one, so that even if there are two objects to be detected, the position of only one object may be detected. Conventional object detection devices such as the object detection device described in the above Patent Document 1 cannot solve the above problem caused by the reinforcement of the two indirect waves.

[0007] To provide an object detection device improved so that, in a situation where two objects to be detected are present, the positions of two objects can be estimated even when indirect waves, which are waves simultaneously transmitted by two sonars and reflected by the objects, reinforce each other.

[0008] [Means for solving the problems and effects of the invention] According to the present invention, there is provided an object detection device (100) including first to third sonars arranged at a distance from each other on the outer periphery of a vehicle (102) such that a third sonar (B) is located between the first and second sonars (A, C), and a control unit (driving assistance ECU 10) that controls the first to third sonars, wherein the first and second sonars are configured to simultaneously transmit sound waves and receive direct waves that are sound waves reflected by an object, and the third sonar is configured to receive indirect waves that are sound waves transmitted by the first and second sonars and reflected by the object, and the control unit is configured to estimate the position of the object that reflected the direct waves and indirect waves based on the time of flight of the direct waves and the indirect waves.

[0009] In a situation where the first and second sonars (A, C) receive direct waves and the third sonar (B) receives indirect waves, when the peak value of the indirect waves received by the third sonar is equal to or greater than a predetermined magnification (Yamax) relative to the peak value of the direct waves received by the first and second sonars (S40), the control unit (driving assistance ECU10) is configured to estimate (S60) the position of an object present within the detection range of the first sonar based on the flight time of the direct wave received by the first sonar (A) and the flight time of the indirect wave received by the third sonar (B), and to estimate (S60) the position of an object present within the detection range of the second sonar based on the flight time of the direct wave received by the second sonar (C) and the flight time of the indirect wave received by the third sonar.

[0010] According to the above configuration, in a situation where the first and second sonars receive direct waves and the third sonar receives indirect waves, when the peak value of the indirect wave received by the third sonar is equal to or greater than a predetermined ratio relative to the peak value of the direct wave received by the first and second sonars, the position of an object is estimated as follows: That is, the position of an object present within the detection range of the first sonar is estimated based on the flight time of the direct wave received by the first sonar and the flight time of the indirect wave received by the third sonar. Also, the position of an object present within the detection range of the second sonar is estimated based on the flight time of the direct wave received by the second sonar and the flight time of the indirect wave received by the third sonar.

[0011] Therefore, in a situation where there are two objects to be detected, even if the two indirect waves transmitted by the first and second sonars and received by the third sonar combine into one due to constructive interference, the positions of the two objects can be estimated.

[0012] [Mode of the invention] In one aspect of the present invention, in a situation where the first and second sonars (A, C) receive direct waves and the third sonar (B) receives indirect waves, when the peak value of the indirect waves received by the third sonar is less than a predetermined magnification (Yamax) relative to the peak value of the direct waves received by the first and second sonars, the control unit (driving assistance ECU10) is configured to estimate which of the first and second sonars corresponds to the indirect waves received by the third sonar (S80, S110), and estimate the position of an object present in the detection range of the estimated sonar based on the flight time of the direct waves received by the estimated sonar and the flight time of the indirect waves received by the third sonar (S90, S120).

[0013] In another aspect of the present invention, the first and second sonars (A, C) are configured to transmit sound waves encoded with different codes by frequency modulation, and the control unit (driving assistance ECU10) is configured to estimate (S80, S110) the sonar corresponding to the indirect wave received by the third sonar (B) based on the code of the indirect wave received by the third sonar.

[0014] Furthermore, in another aspect of the present invention, when only one of the first and second sonars receives direct waves and the third sonar receives indirect waves (S70, S100), the control unit (driving assistance ECU10) is configured to estimate (S90, S120) the position of an object present within the detection range of one of the sonars based on the flight time of the direct wave received by the one sonar and the flight time of the indirect wave received by the third sonar.

[0015] Furthermore, in another aspect of the present invention, the overlapping range (S) is defined as the detection area by direct waves received by the first sonar (A) and the detection area by indirect waves received by the third sonar (B), and the ratio of the distance between any point (X) within the overlapping range and the first sonar to the distance between any point and the third sonar is defined as a predetermined ratio, and the predetermined magnification is the maximum value of the predetermined ratio.

[0016] Other objects, features and attendant advantages of the present invention will become readily apparent from the following description of the embodiments of the present invention which are given with reference to the accompanying drawings. [Brief description of the drawings]

[0017] [Figure 1] 1 is a schematic configuration diagram showing an object detection device according to an embodiment; [Diagram 2] FIG. 13 is a diagram showing the sequence of operations of sonars A to D on the front end side of the embodiment. [Diagram 3] 1A is a diagram showing a state in which indirect waves reinforce each other when there are two obstacles (A) and when there is one obstacle (B). FIG. [Figure 4] FIG. 1 is a diagram showing the peak values ​​of two indirect waves (A, B) and the peak value when the indirect waves reinforce each other (C). [Diagram 5] This figure shows a case X1 (case 1) in which indirect ultrasonic waves transmitted simultaneously by sonars A and C reinforce each other, and a case X2 (case 2) in which only the indirect ultrasonic wave transmitted by one of sonars A and C is received by sonar B. [Figure 6] 5 is a flowchart showing the first half of an object detection control routine according to the embodiment. [Figure 7] 10 is a flowchart showing a second half of an object detection control routine according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An object detection device according to an embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

[0019] 1, an object detection device 100 according to an embodiment of the present invention is applied to a vehicle 102 and includes a driving assistance ECU 10. The vehicle 102 may be an autonomous vehicle, and includes a drive ECU 20, a braking ECU 30, and a meter ECU 40. The ECU stands for an electronic control unit having a microcomputer as a main component.

[0020] The microcomputer of each ECU includes a CPU, ROM, RAM, a readable / writable non-volatile memory (N / M), and an interface (I / F). The CPU realizes various functions by executing instructions (programs, routines) stored in the ROM. Furthermore, these ECUs are connected to each other via a Controller Area Network (CAN) 104 so that they can exchange data (communicate). Therefore, the detection values ​​of sensors (including switches) connected to a specific ECU are also sent to other ECUs.

[0021] The driving assistance ECU 10 detects objects such as fences, guardrails, and other vehicles around the vehicle 102, and estimates the position of the object, i.e., the distance between the object and the vehicle and the direction of the object relative to the vehicle. In the embodiment, the driving assistance ECU 10 cooperates with other ECUs to issue an alarm indicating that the vehicle has come too close to an object, and prevents the vehicle from colliding with the object by controlling the driving force and braking force of the vehicle 102 as necessary.

[0022] Sonars A to D and sonars E to H are connected to the driving assistance ECU 10 and are controlled by the driving assistance ECU 10. As shown in Fig. 2, sonars A to D are disposed on the outer periphery of the front end of the vehicle 102. Sonar B is located between sonar A and sonar C, and sonar C is located between sonar B and sonar D. Although not shown in the figure, sonars E to H are disposed on the outer periphery of the rear end of the vehicle 102. Sonar F is located between sonar E and sonar G, and sonar G is located between sonar F and sonar H.

[0023] Further, a front end switch 12F and a rear end switch 12R are connected to the driving assistance ECU 10. When the front end switch 12F is on, the driving assistance ECU 10 controls the front end sonars A to D, and when the rear end switch 12R is on, the driving assistance ECU 10 controls the rear end sonars E to H. Note that the front end switch 12F and the rear end switch 12R may be integrated into one switch, in which case the driving assistance ECU 10 controls the front end sonars A to D and the rear end sonars E to H when one switch is on.

[0024] Each sonar is configured to transmit ultrasonic waves in a direction away from the vehicle 102, receive ultrasonic waves transmitted by its own sonar and reflected by an object, i.e., direct waves, and also receive ultrasonic waves transmitted by other sonars and reflected by objects, i.e., indirect waves. Each sonar is also configured to output to the driving assistance ECU 10 a signal indicating the peak value of the received voltage corresponding to the received ultrasonic waves, and therefore a signal indicating the peak value of the received ultrasonic waves.

[0025] The driving assistance ECU 10 determines that the corresponding sonar is receiving ultrasonic waves when the wave height value is equal to or greater than a reference value. Therefore, the driving assistance ECU 10 can clearly determine whether the sonar is receiving ultrasonic waves or not. In addition, the driving assistance ECU 10 estimates the distance between the object that reflected the direct wave and the indirect wave and the vehicle 102 and the direction of the object relative to the vehicle based on the flight times of the direct wave and the indirect wave.

[0026] In the embodiment, in order to increase the object detection efficiency, the driving assistance ECU 10 controls the sonars in any of the sonar groups, the sonars A to D on the front end side and the sonars E to H on the rear end side, so that two sonars simultaneously transmit ultrasonic waves of different frequencies from each other. An operation mode in which two sonars simultaneously transmit ultrasonic waves is called a dual mode, and an operation mode in which only one sonar transmits ultrasonic waves is called a single mode. When the operation mode is the dual mode, a means known in the art other than encoding the ultrasonic waves into different codes by frequency modulation encoding to make the frequencies of the ultrasonic waves different from each other may be adopted as a means for determining which sonar receives the indirect waves and transmits the indirect waves.

[0027] In particular, in the embodiment, as shown in Fig. 2, when the front end switch 12F is on, the driving assistance ECU 10 controls the sonars A to D on the front end side so that the first and second wave transmission and reception modes are alternately repeated. In the first wave transmission and reception mode, the sonars A and C simultaneously transmit ultrasonic waves as the first and second sonars, respectively, and receive direct waves, and the sonars B and D receive indirect waves, and the sonar B functions as the third sonar. In the second wave transmission and reception mode, the sonars B and D simultaneously transmit ultrasonic waves as the first and second sonars, respectively, and receive direct waves, and the sonars A and C receive indirect waves, and the sonar C functions as the third sonar.

[0028] Similarly, when the rear end switch 12R is on, the driving assistance ECU 10 controls the rear end sonars E to H so that the third and fourth wave transmission / reception modes are alternately repeated. In the third wave transmission / reception mode, the sonars E and G simultaneously transmit ultrasonic waves as the first and second sonars, respectively, and receive direct waves, and the sonars F and H receive indirect waves, and the sonar F functions as the third sonar. In the fourth wave transmission / reception mode, the sonars F and H simultaneously transmit ultrasonic waves as the first and second sonars, respectively, and receive direct waves, and the sonars E and G receive indirect waves, and the sonar G functions as the third sonar.

[0029] In any of the first to fourth wave transmission / reception modes, the first and second sonars determine whether the ultrasonic waves reflected by an object are direct waves or indirect waves based on the frequency of the ultrasonic waves reflected by the object, and the third sonar determines which sonar transmitted the indirect waves based on the frequency of the received indirect waves.

[0030] A drive device 22 that accelerates the vehicle 102 by applying a drive force to drive wheels not shown in Fig. 1 is connected to the drive ECU 20. The drive ECU 20 normally controls the drive device 22 so that the drive force generated by the drive device 22 changes according to the driving operation by the driver, and when a command signal is received from the driving assistance ECU 10, the drive ECU 20 controls the drive device 22 based on the command signal.

[0031] The drive device 22 is not limited to a combination of an internal combustion engine and an automatic transmission. That is, the drive device 22 may be any drive device known in the art, such as a combination of an internal combustion engine and a continuously variable transmission, a so-called hybrid system which is a combination of an internal combustion engine and a motor, a so-called plug-in hybrid system, a combination of a fuel cell and a motor, or a motor.

[0032] A braking device 32 that applies braking force to wheels not shown in Fig. 1 to decelerate the vehicle 102 through braking is connected to the braking ECU 30. The braking ECU 30 normally controls the braking device so that the braking force generated by the braking device 32 changes according to the braking operation by the driver, and when it receives a command signal from the driving assistance ECU 10, it controls the braking force of each wheel by controlling the braking device 32 based on the command signal.

[0033] An alarm device 42 is connected to the meter ECU 40. The alarm device 42 is activated when it is determined that the vehicle 102 is approaching an obstacle excessively and is likely to collide with the obstacle, and issues an alarm, i.e., issues an alarm that the vehicle 102 is approaching an obstacle excessively and is likely to collide with the obstacle. The alarm device 42 may be any of an alarm device that issues a visual alarm such as a display or an alarm lamp, an alarm device that issues an auditory alarm such as an alarm buzzer, an alarm device that issues a bodily alarm such as seat vibration, or any combination thereof.

[0034] As mentioned above, the rear end sonars E-H are controlled in the same way as the front end sonars A-D, so from here on only the front end sonars A-D will be described.

[0035] As shown in Fig. 3(A), it is assumed that an ultrasonic wave transmitted by sonar A is reflected by an obstacle 50, and the reflected wave, i.e., an indirect wave, is received by sonar B, and the relationship between the peak value of the received voltage for the indirect wave and the TOF (time of flight) is as shown in Fig. 4(A). It is also assumed that an ultrasonic wave transmitted by sonar C is reflected by an obstacle 52, and the reflected wave, i.e., an indirect wave, is received by sonar B, and the relationship between the peak value of the received voltage for the indirect wave and the TOF is as shown in Fig. 4(B).

[0036] When the TOF at which the crest value of the indirect wave of the ultrasonic waves simultaneously transmitted by sonars A and C reaches its peak value is the same and the phase difference between the two indirect waves is 0 degrees or close to it, the two indirect waves reinforce each other. Therefore, the relationship between the crest value of the received voltage of sonar B and the TOF is as shown in Figure 4(C), and sonar B is determined to have received only one indirect wave.

[0037] When one indirect wave is estimated to be an indirect ultrasonic wave transmitted by sonar A, the position of obstacle 50 can be estimated by triangulation based on the TOF of the direct wave received by sonar A and the TOF of one indirect wave received by sonar B. However, since sonar B is determined not to have received an indirect ultrasonic wave transmitted by sonar C, it cannot estimate the position of obstacle 52.

[0038] On the other hand, if one indirect wave is estimated to be an indirect ultrasonic wave transmitted by sonar C, the position of the obstacle 52 can be estimated by triangulation based on the TOF of the direct wave received by sonar C and the TOF of one indirect wave received by sonar B. However, since sonar B is determined not to have received an indirect ultrasonic wave transmitted by sonar A, it cannot estimate the position of the obstacle 50.

[0039] [Principle of the present invention] When sonars A and C transmit ultrasonic waves simultaneously and sonar B receives only one indirect wave, the case falls into either case 1 or 2 below.

[0040] Case 1 is a case where the indirect ultrasonic waves transmitted simultaneously by sonars A and C reinforce each other, and sonar B receives only one indirect wave (Figure 5 (X1)).

[0041] In contrast, in case 2, only the indirect ultrasonic waves transmitted by one of sonars A and C are received by sonar B, and the obstacle is outside the detection area of ​​the other sonar (Figure 5 (X2)).

[0042] Let S be the range where the detection area by the direct waves received by sonar A overlaps with the detection area by the indirect waves received by sonar B. As shown in the following formula (1), let X be any point within range S, and let Ya be the ratio of the distance between point X and sonar B to the distance between point X and sonar A. That is, for ultrasonic waves reflected at point X, the maximum value of the magnification of the peak value of the indirect wave to the peak value of the direct wave is obtained in advance as the maximum value Yamax of the ratio Ya, and this is set as the predetermined magnification. Ya = distance between point X and sonar B / distance between point X and sonar A … (1)

[0043] If the ratio of the peak value of the direct wave received by sonar A to the peak value of the direct wave received by sonar C to the peak value of the indirect wave received by sonar B is both greater than or equal to a predetermined magnification Yamax, it is determined that the case is case 1 rather than case 2.

[0044] In particular, in the embodiment, when sonars A and C receive direct ultrasonic waves transmitted simultaneously from sonars A and C, respectively, and sonar B receives only one indirect wave, it is estimated as follows whether the two indirect waves reinforce each other to become one indirect wave.

[0045] If the peak value of the indirect wave received by sonar B is equal to or greater than a predetermined magnification Yamax with respect to the peak value of the direct wave received by sonars A and C, it is determined that mutual reinforcement of the indirect waves is occurring (case 1). Then, as shown in FIG. 5 (X1), the position of obstacle P is estimated based on the TOF of the direct wave received by sonar A and the TOF of the indirect wave received by sonar B. Furthermore, the position of obstacle Q is estimated based on the TOF of the direct wave received by sonar C and the TOF of the indirect wave received by sonar B.

[0046] On the other hand, if the peak value of the indirect wave received by sonar B is less than a predetermined magnification Yamax with respect to at least one of the peak values ​​of the direct waves received by sonars A and C, it is determined that the indirect waves are not reinforced (case 2). Then, as shown in FIG. 5 (X2), it is determined whether the indirect wave received by sonar B is an indirect wave of ultrasonic waves transmitted by sonar A or C, based on the code encoded by frequency modulation. Then, based on the TOF of the direct wave of the determined sonar and the TOF of the indirect wave received by sonar B, the position of obstacle P is estimated.

[0047] The ROM of the driving assistance ECU 10 stores, as an embodiment of the object detection control program, an obstacle detection control program corresponding to the flowcharts shown in Figures 6 and 7. The CPU of the driving assistance ECU 10 executes obstacle detection control according to this obstacle detection program in order to solve a problem in which indirect waves reinforce each other when the operation mode is set to the dual mode, making it impossible to estimate the position of one of two obstacles.

[0048] <Obstacle detection control program> Next, an obstacle detection control program in the embodiment will be described with reference to the flowcharts shown in Figures 6 and 7. The obstacle detection control according to the flowcharts shown in Figures 6 and 7 is repeatedly executed by the CPU of the driving assistance ECU 10 when the front end switch 12F is on. At the start of the obstacle detection control, the operation mode is set to the dual mode.

[0049] First, in step S10, the CPU controls the sonars A and C so that the sonars A and C simultaneously transmit ultrasonic waves.

[0050] In step S20, the CPU controls the sonars A to D so that the sonars A and C receive direct waves and the sonars B and D receive indirect waves.

[0051] In step S30, the CPU determines whether or not sonars A and C are receiving direct waves. If the CPU determines negative, that is, if at least one of sonars A and C is not receiving direct waves, the CPU advances this control to step S70, and if the CPU determines positive, the CPU advances this control to step S40.

[0052] In step S40, the CPU determines whether the peak value of the indirect wave received by sonar B is equal to or greater than a predetermined magnification Yamax with respect to the peak value of the direct wave received by sonars A and C. If the CPU makes a negative determination, i.e., if the peak value of the indirect wave received by sonar B is less than the predetermined magnification Yamax with respect to at least one of the peak values ​​of the direct waves received by sonars A and C, the CPU advances this control to step S70. In contrast, if the CPU makes a positive determination, the CPU advances this control to step S50.

[0053] In step S50, the CPU determines that the indirect wave received by sonar B is an indirect wave of the ultrasonic waves received by sonars A and C, and that the two indirect waves are constructive with each other.

[0054] In step S60, the CPU estimates the position of an obstacle P based on the TOF of the direct wave received by sonar A and the TOF of the indirect wave received by sonar B. Furthermore, the CPU estimates the position of an obstacle Q based on the TOF of the direct wave received by sonar C and the TOF of the indirect wave received by sonar B.

[0055] In step S70, the CPU determines whether or not sonar B is receiving indirect waves. If the CPU makes a negative determination, it advances control to step S100, and if the CPU makes a positive determination, it advances control to step S80.

[0056] In step S80, the CPU estimates whether the sonar that transmitted the ultrasonic waves forming the indirect waves is sonar A or sonar C, based on the code of the indirect waves received by sonar B. Note that, when it is determined in step S30 that sonar C has not received the direct waves, the sonar that transmitted the ultrasonic waves forming the indirect waves may be estimated to be sonar A.

[0057] In step S90, the CPU estimates the position of the obstacle based on the TOF of the direct wave received by the estimated sonar and the TOF of the indirect wave received by sonar B. For example, when the estimated sonar is sonar A, the CPU estimates the position of the obstacle based on the TOF of the direct wave received by sonar A and the TOF of the indirect wave received by sonar B.

[0058] In step S100, the CPU determines whether or not the sonar D is receiving an indirect wave. If the CPU makes a negative determination, the control proceeds to step S210, and if the CPU makes a positive determination, the control proceeds to step S110.

[0059] In step S110, the CPU estimates whether the sonar that transmitted the ultrasonic waves forming the indirect waves is sonar A or sonar C, based on the code of the indirect waves received by sonar D. Note that, when it is determined in step S30 that sonar A has not received the direct waves, the sonar that transmitted the ultrasonic waves forming the indirect waves may be estimated to be sonar C.

[0060] In step S120, the CPU estimates the position of the obstacle based on the TOF of the direct wave received by the estimated sonar A and the TOF of the indirect wave received by sonar B, similarly to step S90 described above.

[0061] Next, the CPU executes steps S210 to S330 shown in Fig. 7. As can be seen from a comparison between Fig. 7 and Fig. 6, steps S210 to S320 are executed in the same manner as steps S10 to S120, respectively. Therefore, detailed description of steps S210 to S320 will be omitted.

[0062] In steps S210, S230 to S260, sonars A and C are replaced with sonars B and D, and in steps S240 to S260, S270 and S290, sonar B is replaced with sonar C. Furthermore, in steps S300 and S320, sonar D is replaced with sonar A.

[0063] Although not shown in the figure, the overlapping range of the detection area by the direct waves received by sonar B and the detection area by the indirect waves received by sonar C is defined as S. As shown in the following formula (2), any point existing within range S is defined as X, and the ratio of the distance between point X and sonar C to the distance between point X and sonar B is defined as Yb. The maximum value Ybmax of the ratio Yb is obtained in advance, and this is defined as the predetermined magnification. Yb = distance between point X and sonar C / distance between point X and sonar B … (2)

[0064] In step S290, the CPU estimates the position of the obstacle based on the TOF of the direct wave received by the sonar C estimated in step S280 and the TOF of the indirect wave received by the sonar C.

[0065] Furthermore, in step S320, the CPU estimates the position of the obstacle based on the TOF of the direct wave received by the sonar A estimated in step S310 and the TOF of the indirect wave received by the sonar A.

[0066] Upon completing step S260, S290 or S320, the CPU outputs in step S330 information on the obstacle position estimated in steps S60, S90 or S120 and S260, S290 or S320 to be used for collision determination control, warning control, etc. When a negative determination is made in steps S100 and S300, it is considered that no obstacle is present in the detection areas of the sonars A to D, and therefore a signal indicating that it was not possible to determine the presence or absence of an obstacle may be output.

[0067] Furthermore, the CPU determines whether or not there is a risk of the vehicle 102 colliding with an obstacle in a manner known in the art. If the CPU determines that there is a risk of the vehicle colliding with an obstacle, it outputs a command signal to the drive ECU 20 to reduce the output of the drive device 22 to zero, and outputs a command signal to the brake ECU 30 to activate the brake device 32 to brake the vehicle. Note that the warning device 42 may be activated, and the reduction in the output of the drive device 22 and / or the braking of the vehicle may be omitted.

[0068] <Operation of the embodiment> As described above, steps S210 to S320 are executed in the same manner as steps S10 to S120, respectively, so the operation of the embodiment will be described only for steps S10 to S120.

[0069] C1: Sonar A and C receive direct waves and two indirect waves are constructive with each other. In steps S30 and S40, a positive determination is made. Therefore, in step S60, the position of the obstacle is estimated based on the TOF of the direct waves received by sonars A and C and the TOF of the indirect wave received by sonar B. Therefore, even if two obstacles exist and the indirect waves are combined into one due to constructive interference, the positions of the two obstacles can be estimated.

[0070] C2: Sonars A and C receive direct waves, but the two indirect waves are not reinforced. In step S30, an affirmative determination is made, but in step S40, a negative determination is made, so that step S70 and subsequent steps are executed.

[0071] C3: When at least one of Sonar A and C does not receive direct waves In step S30, a negative determination is made, so in this case as well, step S70 and subsequent steps are executed.

[0072] In the above case of C2 or C3, when sonar B receives an indirect wave, a positive determination is made in step S70. Therefore, in step S80, it is estimated whether the sonar that transmitted the ultrasonic wave forming the indirect wave is sonar A or sonar C, based on the code of the indirect wave received by sonar B. Furthermore, in step S90, the position of the obstacle is estimated based on the TOF of the direct wave received by the estimated sonar and the TOF of the indirect wave received by sonar B.

[0073] In the above cases of C2 or C3, when sonar B does not receive indirect waves and sonar D receives indirect waves, a negative determination is made in step S70, and a positive determination is made in step S100. Therefore, in step S110, based on the code of the indirect waves received by sonar D, it is estimated whether the sonar that transmitted the ultrasonic waves forming the indirect waves is sonar A or sonar C. Furthermore, in step S120, the position of the obstacle is estimated based on the TOF of the direct waves received by the estimated sonar and the TOF of the indirect waves received by sonar B.

[0074] Furthermore, in the case of C2 or C3 above, when sonars B and D do not receive indirect waves, negative determinations are made in steps S70 and S100. Therefore, it is considered that no obstacle is present in the detection areas of sonars A to D, and therefore the position of the obstacle is not estimated.

[0075] In particular, in the embodiment, the maximum values ​​Yamax and Ybmax of the ratios Ya and Yb expressed by the formulas (1) and (2) are set as predetermined magnifications. Therefore, when an obstacle exists in the detection area of ​​the sonars A to D, the position of the obstacle can be estimated.

[0076] Note that the mutual reinforcement of two indirect waves may also occur when there is one obstacle, for example, as shown in Fig. 3(B) when ultrasonic waves transmitted by sonars A and C are reflected by an obstacle 54 and received as indirect waves by sonar B. In this case as well, for example, positive determinations are made in steps S30 and S40, and step S60 is executed, but in step S60, the positions of the obstacles are estimated to be the same position.

[0077] Although the present invention has been described in detail with respect to specific embodiments, the present invention is not limited to the above-described embodiments, and it will be apparent to those skilled in the art that various other embodiments are possible within the scope of the present invention.

[0078] For example, in the embodiment, the maximum values ​​Yamax and Ybmax of the ratios Ya and Yb expressed by the formulas (1) and (2) are set as the predetermined magnification. However, the predetermined magnification may be set to values ​​other than the maximum values ​​Yamax and Ybmax.

[0079] In the embodiment, when a positive determination is made in step S30, step S40 is executed. However, when a positive determination is made in step S30, a determination is made as to whether or not sonar B receives only one indirect wave, and when a positive determination is made, step S40 is executed, and when a negative determination is made, step S70 is executed.

[0080] Similarly, when a positive determination is made in step S230, a determination is made as to whether or not sonar C receives only one indirect wave, and when a positive determination is made, step S240 may be executed, and when a negative determination is made, step S270 may be executed.

[0081] In addition, in the embodiment, the sonars A to D on the front end side and the sonars E to H on the rear end side are received, but the sonars A to D on the front end side or the sonars E to H on the rear end side may be omitted.

[0082] In the embodiment, when the front end switch 12F is on, the front end sonars A to D are controlled, and when the rear end switch 12R is on, the rear end sonars E to H are controlled. However, when the vehicle 102 is in a preset running state, the sonars may be controlled without the need to operate the switches.

[0083] Furthermore, in the embodiment, each sonar transmits ultrasonic waves, but the transmitted sound waves may be sound waves having a lower frequency than ultrasonic waves. [Explanation of symbols]

[0084] 10... driving assistance ECU, A to H... sonar, 22... drive device, 32... braking device, 42... warning device, 100... object detection device, 102... vehicle

Claims

1. an object detection device including first to third sonars arranged at a distance from each other on an outer periphery of a vehicle such that a third sonar is located between the first and second sonars; and a control unit that controls the first to third sonars, the first and second sonars being configured to simultaneously transmit sound waves and receive direct waves that are sound waves reflected by an object, the third sonar being configured to receive indirect waves that are sound waves transmitted by the first and second sonars and reflected by an object, and the control unit being configured to estimate a position of an object that has reflected the direct waves and the indirect waves based on times of flight of the direct waves and the indirect waves; The control unit is configured to estimate the position of an object present within the detection range of the first sonar based on the flight time of the direct wave received by the first sonar and the flight time of the indirect wave received by the third sonar, when the peak value of the indirect wave received by the third sonar is equal to or greater than a predetermined multiple relative to the peak value of the direct wave received by the first and second sonars, and to estimate the position of an object present within the detection range of the second sonar based on the flight time of the direct wave received by the second sonar and the flight time of the indirect wave received by the third sonar.

2. 2. The object detection device according to claim 1, wherein, when the first and second sonars receive direct waves and the third sonar receives indirect waves, the control unit is configured to, when the peak value of the indirect wave received by the third sonar is less than the predetermined multiple of the peak value of the direct wave received by the first and second sonars, estimate which of the first and second sonars corresponds to the indirect wave received by the third sonar, and estimate the position of an object present in the detection range of the estimated sonar based on the flight time of the direct wave received by the estimated sonar and the flight time of the indirect wave received by the third sonar.

3. 3. The object detection device according to claim 2, wherein the first and second sonars are configured to transmit sound waves encoded with different codes by frequency modulation, and the control unit is configured to estimate the sonar corresponding to the indirect wave received by the third sonar based on the code of the indirect wave received by the third sonar.

4. 2. The object detection device according to claim 1, wherein the control unit is configured, when only one of the first and second sonars receives direct waves and the third sonar receives indirect waves, to estimate the position of an object present within the detection range of the one sonar based on the flight time of the direct wave received by the one sonar and the flight time of the indirect wave received by the third sonar.

5. 5. An object detection device as described in any one of claims 1 to 4, wherein an overlapping range is defined as a detection area by direct waves received by the first sonar and a detection area by indirect waves received by the third sonar B, a predetermined ratio is defined as a ratio of a distance between an arbitrary point within the overlapping range and the first sonar to a distance between the arbitrary point and the third sonar, and the predetermined magnification is the maximum value of the predetermined ratio.

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