JP4370860B2 - Object detection device - Google Patents

Description

  The present invention relates to an object detection device that detects the presence of an obstacle or a preceding vehicle existing around a vehicle using a two-dimensional scanner.

  Conventionally, as a technique for detecting an obstacle around a vehicle and a preceding vehicle, a technique described in Patent Document 1 below is known. The optical scanner device described in Patent Document 1 uses a micro scanner whose mirror surface vibrates in two vertical and horizontal directions, and performs two-dimensional scanning by reflecting pulsed light from a laser diode on the mirror surface. ing. Conventionally, the distance and direction from an obstacle are detected by analyzing reflected light obtained by performing two-dimensional scanning.

Further, in a radar apparatus using a two-dimensional scanner, as a technique for detecting the angle of a mirror surface that vibrates in two vertical and horizontal directions, a technique using a position detection element such as PSD (Position Sensitive Device), a mirror support unit And a method of detecting a counter electromotive force superimposed on a drive signal of a drive coil disposed inside the scanner.
JP-A-9-101474 Japanese Unexamined Patent Publication No. 7-44647 JP 7-128602 A JP 7-218857 A JP-A-11-305162 JP 2003-177340 A Japanese Patent Laid-Open No. 7-141457

  However, in the above-described technology for detecting the angle of each mirror surface, in the case of a wide-angle two-dimensional scanner, a PSD having a large light-receiving surface is required, resulting in high cost.

  Further, the technology for detecting piezoresistance has a problem that it is difficult to mount the piezoresistor because the mirror support portion is thin.

  Furthermore, in the technology for detecting the counter electromotive force superimposed on the scanner drive signal, a current proportional to the displacement velocity component flows to the drive coil due to the vibration of the mirror surface, and by integrating the current, the angle and phase of the mirror surface are integrated. However, the phase error is likely to occur due to the influence of the drive pulse signal flowing in the drive coil.

  Further, in the case of a double gimbal type two-dimensional scanner, a signal in which counter electromotive forces of both vibrations are mixed is caused by the influence of crosstalk between the inner coil and the outer coil. When the moving average calculation process is performed from the signal affected by the crosstalk to calculate the displacement speed information of the mirror surface, a phase error is likely to occur, and a phase offset is generated in the angle information of the mirror surface. There was a problem that two targets were detected twice.

  Therefore, the present invention has been proposed in view of the above situation, and it is possible to correct the object detection azimuth by performing phase correction on the angle information of the mirror surface of the scanner obtained from the back electromotive force. It is an object of the present invention to provide an object detection device that can perform the above.

In the present invention, in an object detection device that detects an object by transmitting a transmitted wave and detecting the reflected wave reflected by the object, the reflection surface for transmitting the transmitted wave is longitudinally driven by a longitudinal vibration drive coil. And a transmission means for transmitting the transmission wave while scanning the transmission surface in a two-dimensional direction by vibrating the reflection surface in the horizontal direction by a lateral vibration drive coil, and a reflected wave reflected by the object. A receiving means for receiving, a counter electromotive force applied to the longitudinal vibration driving coil by the longitudinal vibration of the reflecting surface, and a counter electromotive force applied to the lateral vibration driving coil by the lateral vibration of the reflecting surface; Obtaining a waveform representing the vibration of the reflecting surface from the power, estimating phase information of the waveform from the waveform representing the vibration of the reflecting surface, correcting the phase information based on the phase correction amount, and correcting the phase information Waveform Calculating an angle of the reflecting surface in search, and sends the azimuth detecting means for detecting the delivery direction of the delivery wave in accordance with the angle, the phase of the waveform representing the vibration of the reflecting surface as determined by the sending direction detecting means A transmission azimuth correction amount setting means for setting a phase correction amount to be corrected, wherein the transmission azimuth correction amount setting means is configured to reflect a reflected wave reflected from a single object existing near an object vanishing point in the transmission range of the transmission wave. set the phase correction amount for correcting the phase of the waveform detection range represents the vibration of the reflecting surface so as to minimize the delivery direction detection means, the time differential value of the phase information reflecting surface vibrates is positive In this case, the phase correction amount set by the sending azimuth correction amount setting means is added to the phase information that the reflecting surface vibrates, the angle of the reflecting surface is obtained, and the time differential value of the phase information that the reflecting surface vibrates. Is negative Case, the reflective surface by subtracting the phase correction amount which is set by the sending direction correction amount setting means to the phase information of the vibration, determining the angle of the reflecting surface.

  According to the object detection device of the present invention, even when crosstalk occurs in the counter electromotive force waveform between the longitudinal vibration driving coil and the lateral vibration driving coil, the object disappearance in the transmission range of the transmission wave is achieved. Since the vibration phase of the reflecting surface is corrected so that the detection range of the object in the vicinity of the point is minimized, it is possible to detect the accurate orientation of the object.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  The present invention is applied to, for example, an object detection apparatus configured as shown in FIG.

[Configuration of Object Detection Device]
In the object detection apparatus according to the present invention, an optical scanner is mounted, infrared light is emitted as a transmission signal by the optical scanner, a short-time pulse signal is transmitted, and reflected by a target to be detected. A case will be described in which a pulse method in which a distance is calculated by measuring a time until a pulse signal (reflected signal) returned is received is described. Further, in the following description, a case where the object detection device is mounted on a vehicle and a target around the vehicle is a detection target will be described.

  As an object detection method, in addition to laser radar using infrared light, electromagnetic wave radar using electromagnetic waves or the like may be used. Further, as a transmission signal, a continuous wave subjected to frequency modulation or amplitude modulation by a triangular wave is transmitted. In addition, a method of calculating the distance based on the frequency displacement or phase displacement of the reflected signal may be used.

  As shown in FIG. 1, the object detection apparatus includes a signal transmission unit 1, a signal reception unit 2, and a signal processing unit 3. The signal processing unit 3 is connected to a vehicle-side CPU (Central Processing Unit) (not shown). It is configured.

  The signal transmission unit 1 includes a laser diode 11, a mirror 12, a two-dimensional scanner 13, a two-dimensional scanner driving unit 14, and a temperature detection unit 15. In such a signal sending unit 1, when sending a transmission signal, a light emission command is sent from the signal processing unit 3 to the laser diode 11 to drive the laser diode 11, and the infrared laser light emitted from the laser diode 11 is emitted. The light is guided to the two-dimensional scanner 13 through the mirror 12 and a transmission signal is generated by the operation of the two-dimensional scanner 13. Thereby, in the signal transmission part 1, a transmission signal is transmitted ahead of vehicles, for example.

  At this time, in the two-dimensional scanner driving unit 14, in order to two-dimensionally scan the transmission signal transmitted from the infrared laser light reflecting surface of the two-dimensional scanner 13 in front of the vehicle, the reflecting surface of the two-dimensional scanner 13 is moved in the vertical direction and Control to vibrate in two dimensions in the horizontal direction. Here, the two-dimensional scanner driving unit 14 receives the frequency control signal from the signal processing unit 3 and vibrates the reflecting surface of the two-dimensional scanner 13 at a frequency specified by the frequency control signal.

  Further, the temperature detection unit 15 in the signal sending unit 1 detects the temperature of the two-dimensional scanner 13 because the resonance frequency of the two-dimensional scanner 13 may change with time due to a temperature change around the vehicle. Send to processing unit 3.

  The signal receiving unit 2 includes a photodiode 21 and an optical lens 22 that receive a reflected signal reflected by an object existing in a transmission signal transmission range. In such a signal receiving unit 2, when a reflection signal having a different incident angle reflected by an object is scanned by scanning the transmission signal in a two-dimensional direction, the reflected signal having a different incident angle is collected by the optical lens 22. Then, it is sent to the photodiode 21. Thereby, the photodiode 21 sends light reception information corresponding to the intensity of the reflected signal to the signal processing unit 3.

  The two-dimensional scanner 13 is configured, for example, as a double gimbal type micro scanner as shown in FIG. That is, the two-dimensional scanner 13 is provided with a signal sending mirror 41 that reflects infrared laser light and sends it as a reflected signal at a substantially central portion, and the signal sending mirror 41 is mirrored via the longitudinal beam 42. The mirror support 43 is connected to the scanner base substrate 45 via the lateral beam portion 44. In such a two-dimensional scanner 13, the mirror support 43 is supported on the scanner base substrate 45 by the horizontal beam portion 44, and the signal transmission mirror 41 is supported on the mirror support 43 by the vertical beam portion 42. .

  Further, the two-dimensional scanner 13 includes two permanent magnets 46a and 46b for vertical direction for vibrating the signal reflection angle in the vertical direction and two permanent magnets 47a and 47b for horizontal direction for vibrating the signal reflection angle in the horizontal direction. A set of permanent magnets is provided. Thus, in the two-dimensional scanner 13, a vertical magnetic field is applied to the entire scanner base board 45 by the vertical permanent magnets 46a and 46b, and a horizontal magnetic field is applied to the scanner base board 45 by the horizontal permanent magnets 47a and 47b. Apply to the whole.

  Further, although not shown, the two-dimensional scanner 13 has an inner vibration driving coil (longitudinal vibration driving coil) on the back outer frame of the signal transmission mirror 41, and an outer vibration driving coil (lateral vibration) on the rear outer frame of the mirror support 43. The driving coil is wired. Thus, in the two-dimensional scanner driving unit 14, Lorentz is applied to the end of the signal transmission mirror 41 and the end of the mirror support 43 by the amount of current flowing through each coil and the magnetic field applied by each permanent magnet 46, 47. A force is generated, and resonance vibrations of longitudinal vibration and lateral vibration are generated with the longitudinal beam portion 42 and the lateral beam portion 44 as axes.

  As shown in FIG. 3, the two-dimensional scanner drive unit 14 includes a vertical drive signal generator 51, a horizontal drive signal generator 52, and variable gain amplifiers 53 and 54.

  In the two-dimensional scanner driving unit 14, when a driving command for the two-dimensional scanner 13 is input from the signal processing unit 3, a vertical driving signal generator 51 oscillates a vertical vibration signal (vertical driving signal) of a rectangular wave, thereby driving horizontally. The signal generator 52 oscillates a rectangular vibration signal (lateral drive signal). At this time, in the two-dimensional scanner driving unit 14, frequency control for inputting the vertical driving signal and the rectangular wave of the horizontal driving signal generated by the vertical driving signal generator 16 and the horizontal driving signal generator 17 from the signal processing unit 3. The frequency is adjusted according to the signal and output to variable gain amplifiers 53 and 54.

  Note that the vertical drive signal and the horizontal drive signal are initially set to frequencies near the resonance frequency of the two-dimensional scanner 13. This resonance frequency may be any resonance frequency such as primary resonance or secondary resonance of the two-dimensional scanner 13. The frequency of the vertical drive signal and the horizontal drive signal is such that the frequency is close to the resonance frequency signal of the two-dimensional scanner 13 corresponding to the temperature of the two-dimensional scanner 13 detected by the temperature detector 15. 3 is adjusted.

  The variable gain amplifiers 53 and 54 amplify the input vertical drive signal and horizontal drive signal based on the adjustment value indicated by the vibration amplitude control signal from the signal processing unit 3, and send. As a result, the two-dimensional scanner drive unit 14 supplies the longitudinal drive signal to the longitudinal vibration drive coil and the transverse drive signal to the transverse vibration drive coil, thereby causing the signal transmission mirror 41 to move in the longitudinal direction as described above. The transmission signal transmitted from the signal transmission mirror 41 is scanned by vibrating in the horizontal direction.

  In this way, by controlling the operation of the two-dimensional scanner 13 by the two-dimensional scanner driving unit 14, the object detection device transmits a transmission signal so as to perform scanning as shown in FIG. That is, the object detection apparatus transmits a transmission signal in unit time as shown at each observation point in FIG. 4 by vibrating the two-dimensional scanner 13 two-dimensionally by a so-called Lissajous scan.

  The signal processing unit 3 stores a program for obtaining a distance and direction from an object existing in front of the vehicle in a storage unit such as a ROM (Read Only Memory) (not shown), and uses a work area such as a RAM (Random Access Memory). By executing the program by a CPU (Central Processing Unit), each functional unit as shown in FIG. 1 is provided. That is, the signal processing unit 3 is connected to the transmission pulse generation unit 31 connected to the laser diode 11, the transmission direction detection unit 32 connected to the two-dimensional scanner 13, the transmission direction correction unit 33, and the two-dimensional scanner drive unit 14. And a distance detection unit 35 connected to the photodiode 21 and a target recognition processing unit 36, and calculates the distance to the target, the direction and shape of the target, and the like.

  The transmission pulse generator 31 generates a light emission command for causing the laser diode 11 to emit light by a pulse method in order to send a transmission signal to each observation point as shown in FIG. As a result, the transmission pulse generator 31 generates a pulse composed of infrared laser light from the laser diode 11.

  The transmission azimuth detector 32 detects the transmission azimuth of the transmission signal transmitted forward from the signal transmission mirror 41 by monitoring the state of the two-dimensional scanner 13. At this time, the transmission azimuth detector 32 superimposes the reflection surface angle of the signal transmission mirror 41 at the time when the transmission signal is transmitted from the laser diode 11 on the longitudinal vibration driving coil and the lateral vibration driving coil. To calculate the transmission direction of the transmission signal.

  The transmission azimuth correction unit 33 receives the transmission azimuth of the transmission signal detected by the transmission azimuth detection unit 32 and receives correction information for correcting the transmission azimuth from the target recognition processing unit 36. Thereby, the transmission azimuth correction unit 33 corrects the transmission azimuth sent from the transmission azimuth detection unit 32 based on the correction information, and sends the correction to the target recognition processing unit 36 as azimuth information.

  The drive signal adjustment unit 34 sends a control signal for controlling the frequency and amplitude in the vertical and horizontal directions of the signal transmission mirror 41 of the two-dimensional scanner 13 to the two-dimensional scanner drive unit 14. In addition, the drive signal adjustment unit 34 inputs the temperature information of the two-dimensional scanner 13 detected by the temperature detection unit 15, adjusts the frequency of the vertical drive signal and the horizontal drive signal, and adjusts the frequency of the signal transmission mirror 41. Adjust the vibration frequency.

  The distance detection unit 35 detects the transmission timing of the transmission signal by the transmission pulse generation unit 31 and the light reception timing of the reception signal by the photodiode 21, detects the distance to the object existing ahead of the host vehicle, and The data is sent to the recognition processing unit 36.

  At this time, as shown in FIG. 5, when the object detection device gives a light emission command from the transmission pulse generator 31 to the laser diode 11 in accordance with a trigger signal for transmitting a transmission signal (FIG. 5A), the light emission command is At the generated timing, the laser diode 11 generates a light emission pulse having a pulse width τ (FIG. 5B), and transmits a transmission signal from the signal transmission mirror 41 at time t1 (FIG. 5C). Then, the transmission signal is reflected by an object in front of the vehicle, and when the light reception signal is received by the photodiode 21 at time t2 after the time Δt has elapsed from time t1 (FIG. 5D), the distance detection unit 35 performs time. The distance from the object is calculated using Δt.

Here, the distance detection unit 35 sets Δt as the time from when the transmission signal that is pulsed light is transmitted to when the reception signal that is reflected light is received, C as the speed of light, and the distance D between the object detection device and the target. Then, the distance D is expressed by the following formula 1,
D = C · Δt / 2 (Formula 1)
Is obtained by performing the following calculation. Note that the distance detection unit 35 calculates the distance to the target by correcting the error in consideration of the measurement distance error caused by circuit delay or the like when calculating the actual distance. Then, the distance D obtained by the distance detection unit 35 is sent to the target recognition processing unit 36.

  In the target recognition processing unit 36, the distance D to the object is sent from the distance detection unit 35, and corrected direction information is sent from the transmission direction correction unit 33. Thus, the target recognition processing unit 36 recognizes the reflection surface angle of the signal transmission mirror 41 from the azimuth information, thereby detecting the transmission direction of the transmission signal and correlates the transmission direction with the distance D. Then, the target recognition processing unit 36 generates two-dimensional observation data composed of the sending direction and the distance D for each preset observation time.

  In addition, the target recognition processing unit 36 performs, for example, identification processing of a preceding vehicle over a plurality of observation times from the two-dimensional observation data for each observation time, and generates preceding vehicle information and obstacle information. Then, in the target recognition processing unit 36, as the vehicle-side CPU, for example, an ACC (Adaptive Cruise Control) controller that performs preceding vehicle follow-up control so that the distance to the preceding vehicle becomes the set inter-vehicle distance, etc. Send material information.

[Phase correction processing]
Next, a phase correction process for correcting the phase of angle information indicating the angle of the signal transmission mirror 41 in the object detection apparatus to which the present invention is applied will be described. This phase correction processing is performed when the signal transmission mirror 41 is driven in the vertical direction and when it is driven in the horizontal direction, and a phase shift caused by crosstalk of counter electromotive force generated between coils corresponding to each direction. Is to correct.

  That is, as shown in FIG. 6, the object detection apparatus that performs this phase correction processing includes the back electromotive force detection unit 61 and the scanner phase in which the transmission direction detection unit 32 is connected to the two-dimensional scanner 13 and the two-dimensional scanner driving unit 14. The transmission azimuth correcting unit 33 includes a phase waveform differential value detecting unit 71 and a phase correction amount adding / subtracting unit 72.

The back electromotive force detection unit 61 normalizes the back electromotive force extracted from the drive signal of the two-dimensional scanner drive unit 14, and the scanner phase calculation unit 62 integrates the moving average and time to obtain phase information of the scanner reflection surface vibration. Is multiplied by the amplitude value of the signal transmission mirror 41 to output angle information and sent to the transmission azimuth correction unit 33.

  In response to this, the phase waveform differential value detection unit 71 detects the time differential value of the phase waveform, determines whether the sign of the time differential value is positive or negative, and displaces the signal transmission mirror 41. Detect direction. Then, the phase correction amount addition / subtraction unit 72 changes the sign of the phase correction value from the target recognition processing unit 36 based on the positive / negative determination by the phase waveform differential value detection unit 71 to change the phase information from the scanner phase calculation unit 62. It is set as the structure added to. As a result, the transmission azimuth correcting unit 33 corrects an error in the detected phase caused by crosstalk.

Here, the phase correction amount addition / subtraction unit 72 uses the phase correction value based on the fixed phase shift amount generated by the cross-talk of the back electromotive force measured in advance, and performs the calculations of the following formulas 2 and 3. By doing so, the correction angle of the signal transmission mirror 41 is calculated. At this time, when A is the displacement amplitude of the signal transmission mirror 41, a phase delay occurs, and the time differential value of the phase information of the reflection surface vibration is positive, the correction angle of the signal transmission mirror 41 is
A · sin {(phase information of reflection surface vibration) + (phase correction amount)} (Formula 2)
When the phase delay occurs and the time differential value of the phase information of the reflection surface vibration is negative, the correction angle of the signal transmission mirror 41 is
A · sin {(phase information of reflection surface vibration) − (phase correction amount)} (Formula 3)
It is calculated by the following equation.

  Then, the phase correction amount addition / subtraction unit 72 changes the sign of the phase correction value according to the displacement direction of the reflecting surface of the signal transmission mirror 41 and corrects the phase information to correct the detection error of the angle phase information due to the fixed phase shift amount Reduce.

  FIG. 7 shows the simulation results of the phase and amplitude of the back electromotive force waveform when the calculations of Equations 2 and 3 are performed. According to FIG. 7, a corrected phase waveform is obtained by adding or subtracting the phase correction amount from the angle phase information (output phase, output waveform) including an error according to the displacement direction of the signal transmission mirror 41.

  In this object detection device, the resonance frequency of the signal transmission mirror 41 may change with time due to temperature changes, and the phase error due to crosstalk between the coils due to the change in the resonance frequency of the signal transmission mirror 41 may occur. In some cases, the target may not be reliably recognized even if correction based on the above-described fixed phase shift amount is performed. In contrast, the object detection apparatus performs a process of adjusting the phase correction amount during the recognition of the target.

  Here, when obtaining the phase correction amount based on the fixed phase shift amount, the object detection device places a single reflector near the center of the two-dimensional observation area, which is the transmission range of the transmission signal, and varies the phase correction amount. Then, two-dimensional observation is performed, and a phase correction amount is detected so that the detection area and detection area of the target existing at the object vanishing point on the two-dimensional detection screen are minimized both vertically and horizontally. In the object detection apparatus, the phase correction amount is stored in a RAM or the like, and calculations shown in Expression 2 and Expression 3 are performed.

  On the other hand, for example, when adjusting the phase correction amount when the vehicle is running, the object detection device stabilizes the reflected signal near the object vanishing point, such as when following a preceding vehicle at a constant speed on a straight road. In this state, two-dimensional observation is performed while varying the phase correction amount, and the phase correction amount that minimizes the detection area and detection area of the preceding vehicle is detected.

  Such processing for adjusting the phase correction amount is realized by a flowchart for performing a processing procedure as shown in FIG. This process is executed every predetermined period when the vehicle is running, for example.

  First, in step S1, a signal from a steering angle sensor (not shown) or the like is input by the target recognition processing unit 36 in order to determine whether or not the vehicle is traveling straight, and the steering angle is neutral. It is determined whether or not the steering angle fluctuation is within a predetermined range. When the target recognition processing unit 36 determines that the steering angle variation is not within the predetermined range, the target recognition processing unit 36 determines that the vehicle is not traveling in a straight line, ends the process, and determines that the steering angle variation is within the predetermined range. If it is determined, it is determined that the vehicle is running straight and the process proceeds to step S2.

  In step S <b> 2, the target recognition processing unit 36 determines whether the target reflected signal is stably received by the photodiode 21 near the vanishing point for the object detection device.

  In other words, in the target recognition processing unit 36, for example, a target exists at a vanishing point on a monitoring screen for monitoring the front of the vehicle, that is, an object vanishing point in the two-dimensional observation range of the transmission signal. It is determined whether or not the reflected signal reflected at the object vanishing point is in a state where light can be received. Specifically, in the object detection device, when a transmission signal is transmitted a plurality of times near the vanishing point in the two-dimensional observation range, whether the transmission signal is reflected and the reflected signal is detected a plurality of times. Determine whether or not.

  If the target recognition processing unit 36 determines that the target is present near the vanishing point and a stable reflection signal is detected, the process proceeds to step S3. If not, the process ends. To do.

  Next, in step S3, the target recognition processing unit 36 changes the phase correction amount by a sine amount having a predetermined change amplitude, and proceeds to steps S4 and S5.

  The target recognition processing unit 36 performs the phase correction performed in step S3, drives the signal transmission mirror 41 to transmit the transmission signal, and detects the reflected signal by the photodiode 21, and in step S4, It is determined whether or not the detection width of the reflected signal around the vanishing point (detection region in the two-dimensional observation range) has decreased, and in step S5, the detection area of the reflected signal around the vanishing point decreases. Determine whether or not. When the target recognition processing unit 36 determines that both the width and area of the reflected signal have not decreased, it proceeds to step S6 and determines that either the width or area of the reflected signal has decreased. In that case, the process proceeds to step S8.

  In step S8, the target recognition processing unit 36 stores the phase correction amount changed in step S3, and the process returns to step S3 again.

  In step S6, the target recognition processing unit 36 determines whether or not the sine change changed in step S3 is one cycle. If it is determined that the cycle is not one cycle, the process returns to step S3. If it is determined that one cycle has occurred, the process proceeds to step S7.

  In step S7, the target recognition processing unit 36 determines whether or not the phase correction value stored in step S8 is the extreme value (maximum value or minimum value) of the sine change performed in step S3. If it is determined that the value is an extreme value, the correction change width is increased in step S9 and the process returns to step S3. If it is determined that the value is not an extreme value, the process ends.

  By performing such processing, the object detection apparatus varies the phase correction amount and outputs it as correction information to the transmission direction correction unit 33, and obtains direction information of the signal transmission mirror 41 as a result of the phase correction. Can do.

[Driving pulse cycle setting process]
Next, in the object detection apparatus to which the present invention is applied, a process for adjusting the period of the drive pulse output to each coil corresponding to the vertical direction and the horizontal direction in order to drive the signal transmission mirror 41 will be described.

  Here, in the object detection device, it is necessary to supply a driving pulse for driving the signal transmission mirror 41 to the longitudinal vibration driving coil and the lateral vibration driving coil, but the two-dimensional scanner 13 is supplied from the two-dimensional scanner driving unit 14. On the other hand, the back electromotive force is masked in the time domain in which the driving pulse is output, which affects the detection of the back electromotive force waveform. That is, as shown in FIG. 9, the low frequency counter electromotive force waveform in the horizontal direction and the high frequency counter electromotive force waveform superimposed on the counter electromotive force waveform are masked when the driving pulse is generated.

  In order to remove the influence of the driving pulse on the back electromotive force waveform, in the object detection apparatus, the driving signal adjusting unit 34 outputs the driving pulse to be given from the two-dimensional scanner driving unit 14 to the two-dimensional scanner 13. The period is set to an integral multiple of the vibration period within a range in which the vibration operation of the signal transmission mirror 41 can be maintained. Specifically, the object detection device has a counter electromotive force waveform as shown in FIG. 10 by setting the output period of the driving pulse to twice the period of the counter electromotive force waveform shown in FIG. To do.

  Thereby, in the object detection device, the driving pulse generated every period of the counter electromotive force waveform is generated every two periods of the counter electromotive force waveform, and the process of estimating the counter electromotive force waveform is performed, This is performed in a time domain where no driving pulse is generated in the time domain. Therefore, in this object detection apparatus, the counter electromotive force waveform is present in one time period or more in the time region of the driving pulse generation interval that is temporally adjacent, and an error is unlikely to occur in the estimation of the counter electromotive force waveform.

[Effect of the embodiment]
As described above in detail, according to the object detection apparatus to which the present invention is applied, when the two-dimensional scanner 13 is driven, the back electromotive force waveform crosses between the longitudinal vibration driving coil and the lateral vibration driving coil. Even when a talk occurs, the phase of the transmission direction is corrected so that the target detection range in the vicinity of the target vanishing point in the transmission range of the transmission signal is minimized, so the accurate target direction is detected. can do.

  That is, when the double gimbal type two-dimensional scanner 13 is used, since the longitudinal vibration driving coil and the lateral vibration driving coil are arranged close to each other, crosstalk occurs between the coils. Back electromotive force signals of vibrations in the other axis direction are mixed in the mutual coils. When such a back electromotive force waveform is used, a moving average process is performed by applying a frequency band filter to the back electromotive force waveform, the back electromotive force waveform on the low frequency side is estimated, and the vibration speed of the signal transmission mirror 41 is determined. Even if the calculation is performed, since the frequency difference between the vertical direction and the horizontal direction is small, it cannot be completely separated. In particular, a phase shift occurs in the angular phase of the low frequency counter electromotive force waveform. When a phase shift occurs in the angle phase of the signal transmission mirror 41 in this way, a different angle is output depending on the fluctuation direction of the signal transmission mirror 41, and the target 81 as shown in FIG. A false detection screen will appear.

  On the other hand, in the object detection apparatus to which the present invention is applied, the phase angle is corrected by correcting the back electromotive force waveform so that the target 81 is minimized, and a single object is obtained as shown in FIG. The mark 81 can be recognized.

  Further, according to this object detection device, even when the vehicle is traveling, the phase correction amount is changed so that the detection range of the target near the vanishing point is minimized. Even when the resonance frequency of the two-dimensional scanner 13 changes, the orientation of the target can be accurately detected without erroneously detecting the orientation of the target.

  Further, according to this object detection device, the phase correction amount is adjusted when the vehicle is traveling in a straight line, so that the vicinity of the target vanishing point in the transmission range of the transmission signal can be accurately recognized and the target vanishing point can be recognized. It is possible to set a phase correction amount that minimizes the detection range of a target existing in the vicinity, and it is possible to accurately detect the azimuth of the target.

  Furthermore, according to this object detection apparatus, the angle of the signal transmission mirror 41 can be corrected by changing the sign of the phase correction value according to the displacement direction obtained by differentiating the counter electromotive force waveform. The angle of the signal transmission mirror 41 can be accurately corrected by the vibration direction.

  Furthermore, according to this object detection apparatus, since the generation period of the drive pulse applied to the longitudinal vibration drive coil and the transverse vibration drive coil is an integral multiple of the period of the counter electromotive force waveform, The phase of the signal transmission mirror 41 can be corrected without using the masked back electromotive force waveform, and the orientation of the target can be detected more accurately.

  The above-described embodiment is an example of the present invention. For this reason, the present invention is not limited to the above-described embodiment, and various modifications can be made depending on the design and the like as long as the technical idea according to the present invention is not deviated from this embodiment. Of course, it is possible to change.

  That is, in the object detection apparatus described above, the case where the electromagnetic method is used as the driving method of the two-dimensional scanner 13 has been described, but a driving method such as an electrostatic method, a piezoelectric method, or a magnetostrictive film method may be used. In the object detection apparatus, laser radar using infrared light has been described. However, the present invention is not limited to this, and laser radar using visible light, radio wave radar using radio waves, ultrasonic radar using ultrasonic waves, and other methods may be used. The present invention is applicable.

It is a block diagram which shows the structure of the object detection apparatus to which this invention is applied. In the object detection device to which the present invention is applied, it is a top view showing a specific configuration of a two-dimensional scanner. FIG. 3 is a block diagram illustrating a functional configuration of a two-dimensional scanner driving unit in an object detection apparatus to which the present invention is applied. It is a figure for demonstrating the scanning system of a transmission signal in the object detection apparatus to which this invention is applied. In the object detection device to which the present invention is applied, it is a timing chart for explaining processing for obtaining a distance to a target, wherein (a) is a trigger signal, (b) is a light emission pulse, (c) is a transmission signal, (D) is a figure which shows the change of a received signal. It is a block diagram which shows the functional structure of the transmission direction detection part and the transmission direction correction | amendment part in the object detection apparatus to which this invention is applied. In the object detection device to which the present invention is applied, it is a diagram showing the phase and amplitude of the back electromotive force waveform before correction, and the phase and amplitude of the back electromotive force waveform after correction. It is a flowchart which shows the process which adjusts the amount of phase corrections in the object detection apparatus to which this invention is applied. In the object detection device to which the present invention is applied, it is a diagram for explaining the relationship between a back electromotive force waveform, a back electromotive force waveform superimposed on the back electromotive force waveform, and a drive pulse. It is a figure for demonstrating the process which adjusts the generation interval of a drive pulse in the object detection apparatus to which this invention is applied. It is a figure which shows the target detection result at the time of misdetecting the angle of the mirror for signal transmission. It is a figure which shows the target detection result at the time of correct | amending the angle of the mirror for signal transmission in the object detection apparatus to which this invention is applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Signal sending part 2 Signal receiving part 3 Signal processing part 11 Laser diode 12 Mirror 13 Two-dimensional scanner 14 Two-dimensional scanner drive part 15 Temperature detection part 21 Photodiode 22 Optical lens 31 Transmission pulse generation part 32 Transmission direction detection part 33 Transmission direction detection part 33 Correction unit 34 Drive signal adjustment unit 35 Distance detection unit 36 Target recognition processing unit 41 Mirror for signal transmission 42 Vertical beam unit 43 Mirror support 44 Horizontal beam unit 45 Scanner base substrate 46 Permanent magnet for vertical direction 47 Permanent for horizontal direction Magnet 51 Vertical drive signal generator 52 Horizontal drive signal generator 53 Variable gain amplifier 61 Back electromotive force detection unit 62 Scanner phase calculation unit 71 Phase waveform differential value detection unit 72 Phase correction amount addition / subtraction unit 81 Target

Claims (5)

In an object detection device for detecting an object by transmitting a transmission wave and detecting a reflected wave reflected by the object.
A transmission surface for transmitting a transmission wave is vibrated in a vertical direction by a longitudinal vibration driving coil, and the reflection surface is vibrated in a horizontal direction by a lateral vibration driving coil to transmit the transmission wave while scanning in a two-dimensional direction. Means,
Receiving means for receiving a reflected wave reflected from the object by the transmitted wave;
From the back electromotive force applied to the longitudinal vibration driving coil by the longitudinal vibration of the reflecting surface and from the back electromotive force applied to the lateral vibration driving coil by the lateral vibration of the reflecting surface, Obtaining a waveform representing vibration, estimating phase information of the waveform from the waveform representing vibration of the reflecting surface, correcting the phase information based on a phase correction amount, obtaining a waveform of the corrected phase information A sending direction detecting means for calculating an angle of the reflecting surface and detecting a sending direction of the sending wave according to the angle;
A sending azimuth correction amount setting means for setting a phase correction amount for correcting the phase of the waveform representing the vibration of the reflecting surface obtained by the sending azimuth detecting means ;
The transmission azimuth correction amount setting means has a waveform phase representing the vibration of the reflecting surface so that a detection range of a reflected wave reflected from a single object existing near an object vanishing point in the transmission range of the transmission wave is minimized. set the phase correction amount for correcting the,
The sending direction detecting means includes
When the time differential value of the phase information in which the reflecting surface vibrates is positive, the phase correction amount set by the sending azimuth correction amount setting means is added to the phase information in which the reflecting surface vibrates. Find the angle
When the time differential value of the phase information in which the reflecting surface vibrates is negative, the phase correction amount set by the sending azimuth correction amount setting means is subtracted from the phase information in which the reflecting surface vibrates. An object detection device characterized by obtaining an angle. The transmission azimuth correction amount setting means varies the phase correction amount of the waveform representing the vibration of the reflecting surface, and sets the phase correction amount that minimizes the reflected wave detection range within the varied range. The object detection apparatus according to claim 1. The object detection apparatus according to claim 2, wherein the sending direction correction amount setting unit corrects a phase of a waveform representing vibration of the reflecting surface when the vehicle is traveling in a straight line.   The sending azimuth detecting means sets an interval between drive pulses applied to the longitudinal vibration driving coil and the lateral vibration driving coil to an integral multiple of the vibration period of the reflecting surface, and is not a time when the driving pulse is applied. The object detection device according to claim 1, wherein a waveform representing vibration of the reflecting surface is obtained in a region.   The object detection apparatus according to claim 1, wherein the transmitted wave is infrared pulsed light.