JP2006276023A - Device and method for detecting object - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To correct the shift of a laser light, emitted from an object detector in the direction of the emitted light. <P>SOLUTION: The laser light is emitted from a laser radar 3 in the object detector 2 attached in a predetermined height h to a vehicle 1, running from the left to the right, reflected by an overhead sign 41, and received by the laser radar 3. The object detector 2 continuously calculates the distance to the overhead sign 41. The object detector 2 identifies the distance L1 to the overhead sign 41, at the moment when the overhead sign 41 comes out of a light-emitting range of the laser light i.e. when an upper end 31 of the laser light passes through a lower end b of the overhead sign 41, and calculates angle θ with respect to a parallel line 51 of the upper end 31 of the laser light, based on the installation height H of the overhead sign 41 and the installation height h of the object detector 2. The object detector 2 finds and corrects the shift in the optical axis, by subtracting an angle Θ/2 from the calculated angle θ and finding an angle of the optical axis 33 to the parallel line 51. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an object detection apparatus and method, and more particularly, to an object detection apparatus and method capable of adjusting an optical axis to an optimum angle.

  Conventionally, using a laser radar installed in a car, measure the distance between the car and the car that runs in front, and if this distance falls below a safe distance, the driver will be warned to take more distance between the cars, There is an object detection device that automatically controls the speed of the own vehicle to increase the distance from the preceding vehicle. The outline of this apparatus will be described with reference to FIG.

  In FIG. 1, the own vehicle 1 in which the object detection device 2 is installed in front of the vehicle is traveling from left to right in the figure. A preceding vehicle 5 is traveling in the same direction as the own vehicle 1 in front of the own vehicle 1. The laser radar 3 of the object detection device 2 emits (projects) the laser light 4 toward the front of the host vehicle. The laser light 4 is reflected at the rear part of the preceding vehicle 5, and the reflected light is received by the laser radar 3. The object detection device 2 measures the time from when the laser beam 4 is projected by the laser radar 3 until it is reflected by the preceding vehicle 5 and received by the laser radar 3, and from that time, the subject vehicle 1 And the inter-vehicle distance of the preceding vehicle 5 is calculated.

  Then, the object detection device 2 determines that the distance between the vehicle 1 and the preceding vehicle 5 calculated in this way is a preset safe distance (when the preceding vehicle 5 causes an accident or suddenly stops, When it is determined that the vehicle 1 is less than the distance that is considered to avoid danger, the driver of the vehicle 1 is warned to increase the distance between the vehicles, or the speed of the vehicle 1 is automatically controlled. To ensure a safe inter-vehicle distance.

  However, such an object detection device 2 has a problem that the distance from the preceding vehicle 5 cannot be accurately measured as shown in FIG. 2 when the optical axis of the laser light 4 projected by the laser radar 3 is shifted. It was.

  In FIG. 2, the laser light 4 projected by the laser radar 3 is shown in FIG. 1 due to, for example, distortion due to a light collision of the own vehicle 1 or loosening due to secular change of the fixing mechanism that fixes the laser radar 3. Compared with the normal light projecting direction of the laser light 4, the light projecting angle is inclined upward.

  In such a case, the laser radar 3 cannot receive the reflected light of the laser beam 4 until the preceding vehicle 5 approaches the position of the preceding vehicle 5 indicated by a broken line. For this reason, when the inter-vehicle distance between the subject vehicle 1 and the preceding vehicle 5 is longer than the position of the preceding vehicle 5 indicated by the broken line, the object detection device 2 cannot detect the presence of the preceding vehicle 5 as well as the inter-vehicle distance.

  Therefore, the preceding vehicle 5 cannot be detected until the vehicle approaches an abnormality, and there is a problem that the emergency situation cannot be dealt with.

  Further, even when the installation angle of the object detection device 2 to the host vehicle 1 is normal (when the laser beam 4 is projected at a desired angle), the road surface is inclined as shown in FIG. In such a case, the conventional object detection device 2 may not be able to detect the preceding vehicle 5.

  In FIG. 3, the laser light 4 projected by the laser radar 3 of the own vehicle 1 is reflected on the road surface inclined forward and does not reach the preceding vehicle 5. That is, in this case, the object detection device 2 cannot detect the preceding vehicle 5.

  Thus, even when the road surface is inclined, the preceding vehicle 5 cannot be detected until the vehicle approaches abnormally, and an emergency situation cannot be dealt with in some cases.

  In order to solve this problem, for example, Japanese Patent Application Laid-Open No. 11-194169 includes an inclination detection means for detecting the inclination of the apparatus itself with respect to the road surface, and a plurality of detection beams, and an optimum detection beam for the detected inclination is provided. A vehicle object detection device provided with a selection means for selecting is disclosed.

  The vehicle object detection device disclosed in this publication is different from the first laser radar that projects laser light in a direction parallel to the road surface in order to measure the inter-vehicle distance from the preceding vehicle. In order to measure the inclination with respect to the road surface, second and third laser radars that project laser light at a predetermined angle toward the road surface are provided.

  In this vehicle object detection device, the angle of the vehicle object detection device itself with respect to the road surface is calculated based on the measurement results of the distance from the road surface by the second and third laser radars. The angle of the optical axis of the laser light projected from the radar is calculated, and an optimum detection beam is selected from a plurality of detection beams based on the calculation result.

  However, in the invention of the above publication, the angle of the optical axis of the laser beam with respect to the vehicle object detection device is treated as a specified value, and the first laser beam with respect to the road surface indirectly from the angle with respect to the road surface of the vehicle object detection device. The angle of the optical axis is calculated. Therefore, if the angle of the optical axis of the laser beam with respect to the vehicle object detection device differs from a predetermined value set at the time of design due to, for example, an assembly error at the time of manufacturing the device, the angle of the optical axis with respect to the road surface is accurately set. There was a problem that it could not be calculated.

  Moreover, in the invention of the above publication, there is a problem that a change in the road surface directly under the vehicle object detection device can be detected, but a change in the inclination of the road surface in front of the vehicle cannot be detected.

  The present invention has been made in view of such a situation. The laser beam 4 itself can be used to detect and correct an optical axis shift of the laser beam 4, and the road surface can be inclined. Accordingly, the projection angle of the laser beam 4 can be adapted.

  An object detection apparatus according to the present invention includes: an emitting unit that emits a beam; a receiving unit that receives a reflected beam reflected by an object emitted from the emitting unit; and a reflected beam received by the receiving unit. A discriminating means for discriminating whether or not the detected object is a road surface, a measuring means for measuring the distance to the reflection position of the road surface based on the reflected beam received by the receiving means, and a reflection of the road surface measured by the measuring means A calculating unit that calculates a road surface inclination angle based on a distance to the position; and a control unit that controls a beam emission angle based on the road surface inclination angle calculated by the calculating unit. .

  The emitting unit and the receiving unit are, for example, the laser radar 3 of FIG. 14, which emits a beam and receives a reflected beam reflected by a road surface and an object on the road surface. The discriminating means is, for example, the object recognition / distance measuring unit 13 in FIG. 14, and judges whether or not the reflected beam received by the receiving means is a reflected beam from the road surface. The measurement means is, for example, the object recognition / distance measurement unit 13 in FIG. 14, and calculates the distance to the reflection position on the road surface based on the reflected beam received by the reception means.

  The calculating means is, for example, the road surface inclination detecting unit 71 of FIG. 14 and calculates the road surface inclination angle based on the distance to the road surface reflection position measured by the measuring means. The control means is, for example, the light projection angle calculation unit 15 and the light projection angle control unit 16 in FIG. 14, and in the light projection angle calculation unit 15, the road surface is based on the inclination angle of the road surface calculated by the calculation means. The emission angle of the laser beam adapted to the tilt angle is calculated, and the projection angle control unit 16 adjusts the projection angle of the laser beam based on the emission angle calculated by the projection angle calculation unit 15.

  The object detection method of the present invention includes an emission step of emitting a beam, a reception step of receiving a reflected beam reflected by the object emitted by the process of the emission step, and a process of the reception step. A determination step for determining whether an object reflecting the reflected beam is a road surface, a measurement step for measuring a distance to a reflection position on the road surface based on the reflected beam received by the processing of the reception step, and a measurement step The beam output angle is controlled based on the calculation step for calculating the road surface inclination angle based on the distance to the reflection position of the road surface measured by the processing and the road surface inclination angle calculated by the processing of the calculation step. And a control step.

  The emission step is, for example, step S41 in FIG. 15, the reception step is, for example, step S42 in FIG. 15, and the determination step and the measurement step are, for example, step S43 in FIG. Is, for example, step S44 in FIG. 15, and the control step is, for example, step S45, step S46, and step S47 in FIG.

  In the fourth object detection apparatus and method of the present invention, a beam is emitted, the reflected beam is reflected by the object and a reflected beam is received, and the object reflecting the received reflected beam is the road surface. The distance to the road surface reflection position is measured based on the received reflected beam, and the road surface inclination angle is calculated based on the measured distance to the road reflection position. The beam emission angle is controlled based on the inclination angle of the road surface.

  According to the object detection apparatus and method of the present invention, the distance to the road surface is measured based on the received reflected beam, and the inclination angle of the road surface is calculated based on the measured distance to the reflection position of the road surface. Since the beam emission angle is controlled based on the calculated road surface inclination angle, it is possible to accurately detect the preceding vehicle regardless of the road surface inclination.

  The structural example of the target object detection apparatus 2 of this invention is demonstrated with reference to the block diagram of FIG.

  The control unit 11 of the object detection device 2 controls each part of the object detection device 2 based on a predetermined control program set in advance to determine the presence or absence of a preceding vehicle or to detect the preceding vehicle 5. In such a case, the inter-vehicle distance from the preceding vehicle 5 is measured to determine whether the inter-vehicle distance is a safe distance. If the inter-vehicle distance is not a safe distance, a series of processing for issuing a warning to the driver is executed. Further, when information indicating that the overhead sign (or road surface) has been confirmed is input from the object recognition / distance measurement unit 13, the control unit 11 receives the vehicle 1 supplied from the vehicle speed measurement device 21. Referring to the information on the traveling speed, it is determined whether the vehicle 1 is traveling at a stable speed (whether it is not accelerating or not) and is stable (running at a constant speed). If it is determined that there is an optical axis shift, a predetermined process for detecting and correcting an optical axis shift described later is executed.

  The laser radar 3 outputs laser light 4 based on the control of the control unit 11, receives reflected light from an object such as an overhead sign or a preceding vehicle 5, and a reflector such as a road, and performs photoelectric conversion to obtain a signal. Input to the processing unit 12. Further, the laser radar 3 is controlled by the projection angle control unit 16 to adjust the projection angle of the laser beam 4 in the vertical direction with respect to the road surface.

  The signal processing unit 12 performs predetermined signal processing on the laser light 4 output from the laser radar 3 and the signal corresponding to the reflected light, and supplies the signal processing to the object recognition / distance measurement unit 13.

  Based on the signal supplied from the signal processing unit 12, the object recognition / distance measurement unit 13 identifies a reflector such as an overhead sign, the preceding vehicle 5, and a road, and measures and controls the distance to the reflector. To the unit 11, the optical axis deviation detection unit 14, and the safety distance determination unit 17.

  The optical axis deviation detection unit 14 performs a predetermined calculation based on the distance to the reflector input from the object recognition / distance measurement unit 13 and calculates a deviation of the optical axis of the laser beam 4 from the reference direction. When it is determined that the optical axis deviation is smaller than a predetermined deviation angle set in advance as a correctable range, the light projection angle calculation unit 15 is supplied with information on the optical axis deviation angle. When it is determined that the calculated deviation of the optical axis is larger than the correctable range, the warning presenting unit 18 is instructed to issue a warning. Here, the optical axis of the laser beam 4 will be described with reference to FIG.

  In FIG. 5, the laser light 4 projected from the laser radar 3 has a predetermined width in the vertical direction, and the end (boundary of the range having available intensity) is respectively set at the upper end 31 of the laser light. And the lower end 32 of the laser beam. When the angle formed by the laser beam upper end 31 and the laser beam lower end 32 is Θ, the bisector is the optical axis 33. The angle Θ is set in advance to a predetermined value.

  Returning to FIG. 4, when the information on the optical axis deviation angle is input from the optical axis deviation detection unit 14, the light projection angle calculation unit 15 can project the laser beam 4 that can correct the optical axis deviation. The light angle is calculated, and the calculated value is supplied to the light projection angle control unit 16.

  When the information regarding the projection angle is input from the projection angle calculation unit 15, the projection angle control unit 16 controls the laser radar 3 so as to obtain a corresponding projection angle.

  The safety distance determination unit 17 determines whether the inter-vehicle distance from the preceding vehicle 5 is a safe distance based on the distance to the reflector input from the object recognition / distance measurement unit 13; If it is determined that the distance is not safe, the alarm presentation unit 18 is instructed to issue an alarm.

  When an instruction from the optical axis deviation detection unit 14 or the safety distance determination unit 17 is input, the alarm presentation unit 18 issues a corresponding alarm.

  The vehicle speed measurement device 21 constantly measures the speed of the traveling vehicle 1 and supplies it to the control unit 11 of the object detection device 2.

  By the way, when the control unit 11 of the object detection device 2 determines that a predetermined time (for example, one day) has elapsed since the detection processing of the optical axis deviation was performed last time, a series of detection of the optical axis deviation. Start processing.

  Next, optical axis misalignment correction processing using overhead signs will be described with reference to the flowchart of FIG.

  In step S <b> 1, the laser radar 3 projects laser light 4.

  In step S2, the laser radar 3 receives the reflected light reflected by the various objects (reflectors) on the road surface from the laser light 4 projected in step S1.

  In step S <b> 3, the laser radar 3 inputs a signal (reflection signal) corresponding to the reflected light received in step S <b> 2 to the signal processing unit 12. The object recognition / distance measurement unit 13 calculates the presence / absence of the object (reflector) and the distance to the object based on the reflected signal subjected to the predetermined signal processing in the signal processing unit 12.

  In step S <b> 4, the object recognition / distance measurement unit 13 determines whether or not the recognized object (reflector) is the overhead sign 41. The control unit 11 stands by until information indicating that the overhead marker 41 has been confirmed is input from the object recognition / distance measurement unit 13.

  FIG. 7A shows the relationship between the own vehicle 1 traveling from the left to the right and the overhead sign 41 in the figure. The laser radar 3 of the object detection device 2 installed in the host vehicle 1 projects a laser beam 4 in front of the host vehicle 1. As the host vehicle 1 travels, the overhead sign 41 (solid line in the figure) approaches from a distance and approaches the measurement range of the laser radar 3, so that the laser beam 4 is reflected by the overhead sign 41 and laser radar 3 receives this reflected light. This signal is processed by the signal processing unit 12 and then input to the object recognition / distance measuring unit 13. The object recognition / distance measuring unit 13 recognizes the overhead sign 41 by comparing the input signal with a reference signal. The reference signal is measured and stored in advance by experiments or the like. When information indicating that the overhead marker 41 has been recognized is input from the object recognition / distance measurement unit 13 to the control unit 11, the process proceeds to step S5.

  In step S <b> 5, the control unit 11 acquires the traveling speed of the host vehicle 1 from the vehicle speed measuring device 21, and based on that, the host vehicle 1 is traveling at a stable speed (a constant speed). If the vehicle is not traveling at a stable speed, the process returns to step S4 and the above-described process is repeated.

  In step S5, when the control unit 11 determines that the host vehicle 1 is traveling at a stable speed, the process proceeds to step S6, and the object recognition / distance measurement unit 13 determines whether the object recognition / distance measurement unit 13 is a laser. The distance between the laser radar 3 and the overhead sign 41 at the moment (immediately before) when the radar 3 cannot detect the overhead sign 41 is calculated. That is, in FIG. 7A, while the subject vehicle 1 travels in the right direction, the object recognition / distance measuring unit 13 continues to recognize the overhead sign 41, but the distance between the subject vehicle 1 and the overhead sign 41 is the overhead sign lost. When the distance is reached (when the overhead sign 41 is at the position indicated by the broken line (point indicated by ▲) in the figure), the overhead sign 41 comes out above the projection range of the laser beam 4, and the target object Thereafter, the recognition / distance measuring unit 13 cannot recognize the overhead marker 41 (this is referred to as lost). The object recognition / distance measuring unit 13 calculates the distance (the distance indicated by L1 in FIG. 7A) between the laser radar 3 and the overhead sign 41 immediately before the overhead sign 41 cannot be recognized, This is supplied to the shaft misalignment detection unit 14.

  In step S7, the optical axis deviation detecting unit 14 is based on the distance L1 between the laser radar 3 and the overhead sign 41 calculated by the object recognition / distance measuring unit 13 in step S6. Calculate the angle. Details of this processing will be described later.

  In step S8, the optical axis deviation detection unit 14 determines whether or not the optical axis is deviated based on the angle of the optical axis calculated in step S7. If the optical axis is not deviated, the process ends. To do.

  In step S8, if the optical axis deviation detection unit 14 determines that the optical axis has shifted, the process proceeds to step S9.

  In step S9, the optical axis deviation detection unit 14 determines whether or not the optical axis deviation is within a predetermined range preset as a correctable range, and if it is determined that it is within the predetermined range, Proceed to step S10.

  In step S10, the optical axis misalignment detection unit 14 inputs information regarding the angle of the optical axis calculated in step S7 to the light projection angle calculation unit 15, and the light projection angle calculation unit 15 based on this, The projection angle of the laser beam 4 for correcting the deviation is calculated, and information regarding the calculated projection angle is supplied to the projection angle control unit 16. The projection angle control unit 16 controls the laser radar 3 based on the information regarding the projection angle input from the projection angle calculation unit 15 to correct the projection angle of the laser beam 4.

  In step S9, when the optical axis deviation detection unit 14 determines that the deviation of the optical axis is larger than the predetermined range, the process proceeds to step S11, and the optical axis deviation detection unit 14 notifies the warning presenting unit 18 to the driver. Command to present an alarm. In accordance with this command, the alarm presentation unit 18 displays an indicator indicating that the optical axis is deviated, or outputs a voice that indicates that the optical axis is deviated. Informs that the axis is off.

  As described above, the object detection device 2 of the present invention performs a series of processes for correcting the deviation of the optical axis.

  For example, the installation position of the overhead sign 41 is recorded in advance on the recording medium of the car navigation system, and the optical axis deviation detection process of the object detection device 2 is performed in conjunction with the car navigation system. Good. That is, when the car navigation system determines that there is an overhead sign 41 in front of the road on which the vehicle 1 is traveling, the information is supplied to the object detection device 2, and the optical axis is shifted to the object detection device 2. You may make it perform a series of processes which detect this. Further, information regarding the installation height of the overhead sign 41 is also recorded in advance in a recording medium of the car navigation system, and the installation height of the overhead sign 41 is calculated when the optical axis deviation detection unit 14 calculates the deviation of the optical axis. You may make it use the information regarding.

  Furthermore, a specific object on the road (for example, a signboard on the road other than the overhead sign 41 or the exit of the tunnel) is associated with the installation height and registered in the car navigation system in advance, thereby allowing the overhead sign. An object other than 41 may be used to detect an optical axis shift.

  In the above-described example, the laser beam is used as the beam for detection. However, the beam used by the object detection device 2 of the present invention is not limited to the laser beam.

  Next, the outline of the process of step S7 in FIG. 6, that is, the optical axis deviation detection process using the distance L1, will be described with reference to FIG.

  FIG. 8 shows the relationship among the own vehicle 1, the overhead sign 41, and the laser beam 4 at the moment when the laser radar 3 loses the overhead sign 41. The distance L1 between the laser radar 3 and the overhead sign 41 is calculated by the process of step S6 of the object recognition / distance measurement unit 13. The installation height h of the laser radar 3 with respect to the road surface 52 has been measured in advance when the laser radar 3 is attached to the host vehicle 1. As for the installation height H of the overhead sign 41, the height of the lower end of the sign relative to the road surface 52 is set to 5 m as a standard (exception is 4.7 m to 6.0 m) in Japan. The parallel line 51 is a convenience line drawn parallel to the road surface 52 at the installation height h of the laser radar 3.

  Here, when the projection port of the laser beam 4 of the laser radar 3 is a, the lower end of the overhead sign 41 is b, and the point where the perpendicular line and the parallel line 51 intersect from the lower end b to the road surface is c, the triangle abc is acb is a right triangle. The length of the side ab is L1, and the length of the side bc can be calculated by Hh.

Therefore, when ∠bac is θ, the angle θ can be obtained by the following equation.
sinθ = (H−h) / L1

  Incidentally, as shown in FIG. 5, the optical axis 33 is a bisector of the angle Θ formed by the laser beam upper end 31 and the laser beam lower end 32.

  From the above, the angle formed by the optical axis 33 and the parallel line 51 can be obtained by θ−Θ / 2.

  An appropriate angle of the optical axis 33 with respect to the parallel line 51 when the object detection device 2 is installed in the host vehicle 1 is specified in advance within a predetermined range, and a value θ−Θ / 2 is specified in advance. By comparing with the appropriate angle, the vertical deviation of the optical axis 33 can be obtained.

  As described above, using the reflected light from the laser beam 4 projected from the laser radar 3, the deviation of the optical axis is directly obtained, so that the projection angle of the laser beam 4 with respect to the object detection device 2 is Even if there is a large deviation from the ideal value at the time of design, the deviation of the optical axis can be obtained accurately.

  Next, FIG. 7B shows an example in which the optical axis is tilted upward from a predetermined range set in advance. Also in FIG. 7B, as in FIG. 7A, the own vehicle 1 is traveling from the left to the right in the drawing. The laser radar 3 continues to recognize the approaching overhead sign 41. When the overhead recognition lost distance is reached (when the overhead marker 41 is in the position indicated by the broken line), the overhead marker 41 goes out of the field of view of the laser beam 4. At this time, the distance between the laser radar 3 and the overhead sign 41 is L2.

  As shown in the figure, the laser radar 3 when the optical axis shown in FIG. 7B is tilted upward compared to the distance L1 between the laser radar 3 and the overhead sign 41 when the optical axis of FIG. 7A is normal. The distance L2 between the head mark 41 and the overhead sign 41 is short. By calculating the principle described above based on the distance L2, the deviation of the optical axis 33 is obtained. As a result, the magnitude of the deviation exceeds the range in which the object detection device 2 can operate normally. It is judged and a warning is displayed to the driver.

  Based on the principle as described above, the object detection device 2 of the present invention can detect the deviation of the optical axis 33.

  Next, an optical axis deviation correction method using a road surface by the object detection device 2 of the present invention will be described with reference to the flowchart of FIG. In addition, about the process same as the optical axis deviation correction method using an overhead mark, it abbreviate | omits suitably.

  In step S <b> 21, the laser radar 3 projects laser light 4.

  In step S22, the laser radar 3 receives the reflected light reflected by the laser light 4 projected in step S21 on the road surface 52 and various objects (reflectors) on the road surface.

  In step S <b> 23, the laser radar 3 inputs a signal (reflected signal) corresponding to the reflected light received in step S <b> 22 to the signal processing unit 12. The object recognition / distance measuring unit 13 identifies the reflected signal from the road surface 52 based on the reflected signal subjected to predetermined signal processing in the signal processing unit 12 and calculates the distance to the road surface 52.

  Whether or not the light is reflected from the road surface 52 can be determined by previously obtaining a characteristic amount of a reflected signal based on the reflected light from the road surface 52 by an experiment and comparing it with the characteristic amount.

  In step S24, the control unit 11 acquires the traveling speed of the host vehicle 1 from the vehicle speed measuring device 21, and based on the acquired speed, the host vehicle 1 is traveling at a stable speed (a constant speed). If the vehicle is not traveling at a stable speed, the process returns to step S21 and the above-described process is repeated.

  In step S25, the optical axis deviation detecting unit 14 determines the angle of the optical axis in the vertical plane based on the distance between the laser radar 3 and the road surface 52 calculated by the object recognition / distance measuring unit 13 in step S23. calculate. Details of this processing will be described later.

  Thereafter, Step S26 is the same as Step S8 in FIG. 6, Step S27 is the same as Step S9 in FIG. 6, Step S28 is the same as Step S10 in FIG. 6, and Step S29 is the same as Step S11 in FIG. .

  As described above, the optical axis deviation correction process using the road surface 52 is performed.

  Next, the principle of optical axis deviation detection using the road surface 52 will be described with reference to FIG. Note that the principle of the optical axis deviation detection method has many similarities to the detection method using the overhead sign 41 shown in FIG. 8, and therefore detailed description will be omitted as appropriate in the following description.

  In the optical axis misalignment detection method using the road surface 52, the object detection device 2 uses the reflected light from the road surface 52 instead of using the reflected light from the overhead sign 41. As shown in FIG. 10, the laser beam 4 at the lower end 62 of the laser beam is reflected on the road surface 52 at a point e, and the reflected light is received by the laser radar 3. Based on the reflected light, the object recognition / distance measuring unit 13 determines whether the light is reflected from the road surface 52, and the intersection of the projection port d, the laser light lower end 62, and the road surface 52 of the laser radar 3. A distance L3 between e is calculated. The object recognition / distance measuring unit 13 supplies the calculated distance L3 to the optical axis deviation detecting unit 14.

  Based on the distance L3 supplied from the object recognition / distance measuring unit 13 and the installation height h of the laser radar 3, the optical axis deviation detecting unit 14 calculates θ by the following equation.

  sinθ = h / L3

  Then, the optical axis deviation detection unit 14 calculates the angle of the optical axis 63 with respect to the parallel line 51 from the value obtained by subtracting Θ / 2 from θ (θ−Θ / 2).

  As described above, the object detection device 2 can also detect the deviation of the optical axis using the road surface 52. The above-described optical axis misalignment detection method using the road surface 52 can detect a downward optical axis shift and can also detect an upward optical axis shift up to a predetermined angle. is there.

  Note that the object detection device 2 of the present invention is set to perform the optical axis deviation detection process using only the overhead sign 41 and to perform the optical axis deviation detection process using only the road surface 52. can do. In addition, the object detection device 2 of the present invention selects and uses the optical axis deviation detection process using the overhead sign 41 and the optical axis deviation detection process using the road surface 52 as appropriate according to the situation. It can also be set.

  Next, details of the process of correcting the optical axis shift in step S10 in FIG. 6 and step S28 in FIG. 9 will be described with reference to FIGS. FIGS. 11 to 13 illustrate different methods for correcting the deviation of the optical axis. A first method for correcting the deviation of the optical axis will be described with reference to FIG.

  In FIG. 11, the laser beam 4A (dotted line in the figure) projected by the laser radar 3 is shifted upward from the angle of the reference optical axis (the angle at which the preceding vehicle 5 can be accurately detected). To do. Here, in step S8 in FIG. 6 (step S26 in FIG. 9), it is determined that the optical axis is deviated. In step S9 in FIG. 6 (step S27 in FIG. 9), the optical axis deviation can be corrected. It is determined that it is a degree.

  Then, in step S10 in FIG. 6 (step S28 in FIG. 9), the light projection angle calculation unit 15 corrects the optical axis deviation based on the information regarding the angle of the optical axis input from the optical axis deviation detection unit. The projection angle controller 16 controls the laser radar 3 based on the information about the projection angle calculated by the projection angle calculator 15, and projects the light. The angle is corrected from the laser beam 4A to the position of the laser beam 4B.

  As a method of correcting the light projection angle from the laser beam 4A to the position of the laser beam 4B, for example, the object detection device 2 is provided with a drive mechanism for turning the laser radar 3 in the vertical direction in advance. A method is conceivable in which the laser radar 3 is turned by the drive mechanism, and the angle of the optical axis is continuously changed by a predetermined angle calculated by the projection angle calculation unit 15 for correction.

  Note that the method of continuously changing the projection angle of the laser beam 4 is not limited to the method described above.

  Next, a second method for correcting the deviation of the optical axis will be described with reference to FIG. In FIG. 12, the object detection device 2 can switch the projection angle of the laser beam 4 projected by the laser radar 3 by a predetermined angle set in advance. The laser beam 4C, the laser beam 4D and laser light 4E can be selected. The projection angle fresh fish unit 16 projects, for example, from the laser beam 4C to the laser beam 4D or from the laser beam 4C to the laser beam 4E according to the information about the angle of the optical axis calculated by the projection angle calculation unit 15. The optical axis shift is corrected by switching the angle.

  In FIG. 12, the three projection angles of the laser beam 4C, the laser beam 4D, and the laser beam 4E are shown. However, the projection angle is not limited to these three projections. It is also possible to configure the apparatus so that the projection angle can be selected. The difference between the optical axis correction methods shown in FIGS. 11 and 12 is that the optical axis correction method shown in FIG. 11 continuously changes the angle of the optical axis, whereas the correction shown in FIG. The method is to change the optical axis discontinuously.

  Next, a third method for correcting the deviation of the optical axis will be described with reference to FIG. The optical axis correction method shown in FIG. 13 is a combination of the methods shown in FIGS. 11 and 12. That is, in FIG. 13, when the laser beam is too angled above the reference projection angle as in the laser beam 4F (illustrated with a dotted line), the projection angle control unit 16 controls First, the projected laser beam is switched to the laser beam 4G (illustrated by a broken line) having the projection angle closest to the reference projection angle (same as the correction method shown in FIG. 12). Further, the projection angle control unit 16 changes the optical axis of the laser light from the laser light 4G to the laser light 4G ′ (shown by a solid line) (same as the correction method shown in FIG. 11). In this way, the optical axis of the laser beam 4 is corrected.

  The optical axis correction method is not limited to the method described above.

  Incidentally, as described above with reference to FIG. 3, even if the optical axis of the laser beam 4 projected by the laser radar 3 is at an angle that matches the reference, the preceding vehicle 5 is affected by the influence of the road surface inclination. May not be detected. As a result, the vehicle may abnormally approach the preceding vehicle 5 and the driver may be at risk. FIG. 3 shows an example in which the road surface ahead of the host vehicle 1 is an uphill. However, when the road surface ahead of the host vehicle 1 is at a flat angle from the uphill, the flat angle When going downhill, it can happen anywhere else where the slope of the road changes.

  Therefore, an apparatus and method for solving the problem described above, that is, the problem that the object detection apparatus 2 cannot detect the preceding vehicle 5 due to the influence of the road surface inclination will be described below.

  FIG. 14 is a block diagram illustrating a configuration example of such an object detection device 2. In FIG. 14, a road surface inclination detection unit 71 is inserted between the object recognition / distance measurement unit 13 and the projection angle calculation unit 15.

  The road surface inclination detecting unit 71 performs a predetermined calculation based on the information about the distance to the road surface supplied from the object recognition / distance measuring unit 13, detects the inclination of the road surface ahead of the host vehicle 1, and projects the light. It is determined whether it is necessary to change the angle of the optical axis of the laser beam 4 to be changed. As a result, when it is determined that the angle needs to be changed, the timing for changing the angle of the optical axis is calculated. Then, information relating to the inclination angle of the road surface is supplied to the light projection angle calculator 15, and information relating to timing for changing the angle of the optical axis is supplied to the light projection angle controller 16.

  The other configuration is the same as that of the object detection device 2 shown in FIG.

  Next, a process for adapting the optical axis of the laser beam 4 to the road surface inclination will be described with reference to the flowchart of FIG.

  In step S <b> 41, the laser radar 3 projects laser light 4. FIG. 16A shows a situation where the laser radar 3 of the object detection device 2 attached to the host vehicle 1 is projecting the laser beam 4 onto the road surface 52 in front. In FIG. 16, the own vehicle 1 is traveling from left to right in the figure.

  In step S42, the laser radar 3 receives the reflected light reflected by the laser light 4 projected in step S41 on the road surface 52 and various objects (reflectors) on the road surface. In FIG. 16, the laser light 4 is reflected at a point indicated by Δ, and the reflected light is received by the laser radar 3.

  In step S43, the laser radar 3 inputs a signal (reflection signal) corresponding to the reflected light received in step S42 to the signal processing unit 12. The object recognition / distance measuring unit 13 identifies the reflected signal from the road surface 52 based on the reflected signal subjected to predetermined signal processing in the signal processing unit 12 and calculates the distance to the road surface 52.

  In step S44, the road surface inclination detection unit 71 receives the distance to the road surface 52 calculated in step S43 from the object recognition / distance measurement unit 13, and based on this, calculates the inclination angle of the road surface 52, It is determined whether or not the inclination angle is larger than a predetermined angle range set in advance. Details of an example of the calculation method will be described later. As a result, in the case of the road surface 52 shown in FIG. 6A, it is determined that the road surface 52 is not inclined (the inclination angle is within a predetermined angle range), the process returns to step S41, and the above-described processing is repeated.

  Here, as shown in FIG. 6B, it is assumed that a road surface rising up from the point T appears in front of the host vehicle 1 traveling in the right direction from the left in the figure. In FIG. 6B, the road surface 52a on the left side from the point T is a flat road surface, and the road surface 52b on the right side from the point T is an uphill. Then, as shown in FIG. 6B, the laser light 4 projected in step S41 is reflected at the point indicated by Δ and received in step S42, and the distance to the road surface 52b is calculated in step S43. . Here, the distance to the road surface 52b in FIG. 6B is shorter than the distance to the road surface 52 in FIG. 6A.

  In this case, in step S44, the road surface inclination detecting unit 71 determines that the inclination angle of the road surface 52b is larger than a predetermined angle range, and the process proceeds to step S45.

  In step S <b> 45, the road surface inclination detection unit 71 supplies information regarding the road surface inclination angle calculated in step S <b> 44 to the light projection angle calculation unit 15. The projection angle calculation unit 15 calculates the projection angle of the laser beam 4 appropriate for the road surface condition based on the supplied information, and supplies it to the projection angle control unit 16.

  In step S46, the road surface inclination detecting unit 71 calculates the distance to the road surface 52b calculated in step S43, the inclination angle of the road surface 52b calculated in step S44, and the host vehicle 1 supplied from the vehicle speed measuring device 21 to the control unit 11. Referring to the velocity information, the timing for changing the optical axis of the laser beam 4 is calculated and supplied to the projection angle control unit 16.

  In step S47, the projection angle control unit 16 changes the information regarding the projection angle of the laser beam 4 supplied from the projection angle calculation unit 15 and the optical axis of the laser beam 4 supplied from the road surface inclination detection unit 71. The laser radar 3 is controlled based on the information regarding the timing to be changed, and the projection angle of the optical axis is changed to the projection angle calculated by the projection angle calculation unit 15 at the timing calculated by the road surface inclination detection unit 71. FIG. 17 illustrates laser light with the projection angle changed.

  In FIG. 17, the object detection apparatus 2 changes the projection angle from the laser beam 4H (shown by a dotted line) to the laser beam 4J (shown by a solid line). In this way, by changing the projection angle of the laser light, if there is a preceding vehicle 5 ahead, the preceding vehicle 5 can be reliably detected.

  Note that any of the methods shown in FIGS. 11 to 13 can be used as the method of changing the projection angle. However, the method of changing the light projection angle is not limited to the method described above.

  Next, an example of the principle by which the road surface inclination detector 71 calculates the road surface inclination will be described with reference to FIG.

  In FIG. 18, there is a road surface 52 b inclined at a point T in front of the host vehicle 1 traveling in the right direction from the left in the drawing. The laser radar 3 of the object detection device 2 projects laser light 4. At the point R, the laser beam 4 has its lower end 32 reflected from the road surface 52b. The object recognition / distance measuring unit 13 calculates a distance L4 from the projection port Q of the laser light 4 to the point R.

  A line passing through the point R and parallel to the road surface 52a is defined as a parallel line 81. A point perpendicular to the road surface 52a perpendicular to the road surface 52a from the projection port Q of the laser beam 4 intersects with the parallel line 81. Let O be the intersection.

  Here, the installation height of the laser radar 3, that is, the length H from the point O to the point Q has been measured in advance when the object detection device 2 is installed. Further, ∠RQP (hereinafter referred to as ∠Q) is determined by the light projection angle of the optical axis, and the light projection angle control unit 16 manages the light projection angle of the optical axis. Therefore, ∠Q can be calculated based on the projection angle of the optical axis. Further, the triangle PQR is a right triangle with a right angle ∠RPQ.

Therefore, when the coordinates of the point R when the point O is the origin (0, 0) are (x, y), the point R (x, y) is
x = L4sin∠Q
y = H-L4cos∠Q
Is required.

  The road surface inclination detecting unit 71 continuously calculates the coordinates of the point R one by one based on the distance information to the road surface 52 that is constantly supplied from the object recognition / distance measuring unit 13, and based on the obtained plurality of coordinates. The slope of the road surface is calculated. However, since the host vehicle 1 is traveling, the host vehicle 1 is moving from the time when the point R is calculated until the next time the point R is calculated. Therefore, the road surface inclination detecting unit 71 calculates the inclination angle of the road surface by a calculation formula including this movement distance.

  Based on the principle described above, the road surface inclination detecting unit 71 calculates the inclination of the road surface.

  By the way, the above description is an example in which the projection angle of the laser beam 4 is adaptively changed with respect to the uphill, but the projection angle of the laser beam 4 can be adapted also to the downhill. . 19A shows a flat road surface 52, and FIG. 19B shows a flat road surface 52 a and a road surface 52 C that is downhill with the point U as a boundary.

  19A and 19B, the host vehicle 1 is traveling from the left to the right in the figure, and the laser light 4 projected from the laser radar 3 is on the road surface 52 (road surface 52C) at the point indicated by Δ. ) Is reflected. The object recognition / distance measuring unit 13 calculates the distance to the position indicated by Δ. 19B, the distance to the road surface 52C calculated by the object recognition / distance measurement unit 13 is calculated by the object recognition / distance measurement unit 13 on the flat road surface 52 of FIG. 19A. It is longer than the distance. Based on the distance to the road surface 52C, the inclination angle of the road surface can be calculated even on a downhill according to the principle described above.

  In the present invention, by using the method as described above, the object detection device having a function of correcting the deviation of the optical axis and adapting the projection angle of the laser beam 4 according to the inclination of the road surface. Can be realized.

  In the above description, a laser beam is used. However, it is also possible to use a radio wave beam that can ensure a sufficiently sharp directivity such as a millimeter wave.

It is a figure explaining the method of the target object detection by the conventional target object detection apparatus. It is a figure explaining the shift | offset | difference of the optical axis by the conventional target object detection apparatus. It is a figure explaining the problem of the conventional target object detection apparatus. It is a block diagram which shows the structural example of the target object detection apparatus of this invention. It is a figure explaining the optical axis of the laser beam which the target object detection apparatus of FIG. 4 projects. It is a flowchart explaining operation | movement of the target object detection apparatus of FIG. It is a figure explaining the optical axis shift detection method of the target object detection apparatus of FIG. It is another figure explaining the optical axis deviation detection method of the target object detection apparatus of FIG. It is a flowchart explaining the operation | movement by the other optical axis deviation detection method of the target object detection apparatus of FIG. It is a figure explaining the other optical axis deviation detection method of the target object detection apparatus of FIG. It is a figure explaining the method of correct | amending the deviation | shift of the optical axis of the target object detection apparatus of FIG. It is a figure explaining the other method of correct | amending the deviation | shift of the optical axis of the target object detection apparatus of FIG. It is a figure explaining the other method of correct | amending the shift | offset | difference of the optical axis of the target object detection apparatus of FIG. It is a block diagram which shows the other structural example of the target object detection apparatus of this invention. It is a flowchart explaining operation | movement of the target object detection apparatus of FIG. It is a figure explaining the road surface inclination calculation method of the target object detection apparatus of FIG. It is a figure explaining the adaptation method to the road surface inclination of the optical axis of the target object detection apparatus of FIG. It is another figure explaining the road surface inclination calculation method of the optical axis of the target object detection apparatus of FIG. It is another figure explaining the road surface inclination calculation method of the optical axis of the target object detection apparatus of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Own vehicle 2 Object detection apparatus 3 Laser radar 4 Laser beam 5 Leading vehicle 11 Control part 12 Signal processing part 13 Object recognition / distance measurement part 14 Optical axis deviation detection part 15 Light projection angle calculation part 16 Light projection angle control part DESCRIPTION OF SYMBOLS 17 Safety distance determination part 18 Warning presentation part 21 Vehicle speed measuring device 31 Laser beam upper end 32 Laser beam lower end 33 Optical axis 41 Overhead mark 51 Parallel line 52 Road surface 61 Laser beam upper end 62 Laser beam lower end 63 Optical axis 71 Road surface inclination detection part 81 parallel lines

Claims (2)

In an object detection device for detecting an object on a road surface,
Emitting means for emitting a beam;
Receiving means for receiving the reflected beam reflected by the beam emitted by the emitting means and hitting an object;
Discriminating means for discriminating whether or not the object reflecting the reflected beam received by the receiving means is the road surface;
Measuring means for measuring a distance to the reflection position of the road surface based on the reflected beam received by the receiving means;
Calculation means for calculating an inclination angle of the road surface based on a distance to the reflection position of the road surface measured by the measurement means;
An object detection apparatus comprising: control means for controlling an emission angle of the beam based on the inclination angle of the road surface calculated by the calculation means. In an object detection device for detecting an object on a road surface,
An exit step for emitting the beam;
A receiving step in which the beam emitted by the processing of the emitting step receives a reflected beam reflected by an object; and
A determination step of determining whether or not the object that has reflected the reflected beam received by the processing of the reception step is the road surface;
A measurement step of measuring a distance to the reflection position of the road surface based on the reflected beam received by the processing of the reception step;
A calculation step for calculating an inclination angle of the road surface based on a distance to the reflection position of the road surface measured by the measurement step;
A control step of controlling an emission angle of the beam based on the inclination angle of the road surface calculated by the processing of the calculation step.

Images