JPH1184006A - Radar equipment mounted on vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radar equipment mounted on a vehicle which can make the detected result of each scanning which has detected the same angle position correspond to each other, when the rotational speed of a rotary shaft is changed by environmental change. SOLUTION: An irradiation timing forming process is started every rotation of a polygon mirror, and forms the incidence timing of a laser light to six mirror surfaces of the polygon mirror. In this process, a timer value t1 showing the present timing, a timer value t0 at the time when a main process is started at the last time, and a rotational period Tm0 are read (S210, S220), a rotational period Tm1(=|t0-t1|) and a mean period Tav(=(Tm0×9+Tm1)/10) are calculated (S230, S260), a scanning start interval Tem(=Tav/6) and the like are calculated (S270, S280, S290). Since the scanning start interval Tem is set from the obserbed value of the rotational period of the polygon mirror, the respective mirror surfaces are irradiated with the laser light with the same timing, independently of change of the rotational period.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an on-vehicle radar device which repeatedly emits a search wave along a predetermined scanning direction in order to collect data used for recognizing an obstacle around a vehicle.

[0002]

2. Description of the Related Art Hitherto, it has been applied to a device for detecting a preceding vehicle and other obstacles and generating an alarm, and a device for controlling a vehicle speed so as to maintain a predetermined inter-vehicle distance with the preceding vehicle. An in-vehicle vehicle that irradiates a search wave such as a millimeter wave over a predetermined angle around the vehicle (hereinafter referred to as scanning) and detects the reflected wave to collect data for recognizing a preceding vehicle or other obstacles Radar devices are known.

In this type of apparatus, especially when laser light is used as a search wave, a rotating polygon mirror having a plurality of reflecting surfaces on an outer peripheral portion is one of means for scanning the laser light. Used, for example,
No. 83511 and Japanese Patent Application Laid-Open No. 4-279890.

[0004]

By the way, an on-vehicle radar device using such a rotating polygon mirror is generally constructed such that the rotating shaft of the rotating polygon mirror is driven by a motor. It is necessary to drive this motor at a constant rotation speed so that the rotation cycle of the motor becomes constant.

However, since the motor is simply driven at a constant current for the reason of simplifying the device configuration and the like, and precise control using feedback is not performed, the ambient temperature and the battery are not usually controlled. Due to various factors such as a change in voltage, the rotation cycle of the motor slightly changes every week.

For example, when the rotation period of the motor (that is, the rotation period of the polygon mirror) is longer than a predetermined rotation period, as shown in FIG.
The laser beam irradiation is started before reaching the point A where the laser beam irradiation should be started. Then, with the progress of the rotation, this shift is accumulated, and the irradiation area of the laser beam slightly shifts for each reflection surface, so that the scanning area for each scan slightly shifts in the direction opposite to the scanning direction. .
In particular, when two-dimensional scanning is performed, FIG.
As shown in FIG. 2B, a rhombic area distorted in the scanning direction is scanned instead of a rectangular area.

As a result, when one-dimensional scanning is performed, it is detected that the detected obstacle is moving in the scanning direction despite being stationary in the scanning direction. In addition, when two-dimensional scanning is performed, the object to be detected is distorted and is detected, and the detection accuracy is deteriorated.

The present invention has been made in order to solve the above problems.
It is an object of the present invention to provide an on-vehicle radar device capable of making the detection results of each scan detected in the same direction (point) correspond to each other even if the rotation speed of the rotation shaft changes due to a change in environment.

[0009]

According to a first aspect of the present invention, there is provided an on-vehicle radar apparatus for achieving the above object, wherein the reference position detecting means determines that the rotational position of the rotary shaft is at a specific reference position. When detecting that, the irradiation starting means starts the irradiation means in accordance with the detection timing of the reference position. Then, the irradiating unit irradiates the search wave at a constant irradiation interval and a predetermined number of times, and the scanning unit determines the irradiation direction of the search wave according to the rotation angle of the rotating shaft driven by the motor. Scanning by a search wave is performed by changing along the scanning direction.

At this time, the cycle calculating means calculates the rotation cycle of the rotating shaft based on the detection result of the reference position detecting means, and in accordance with the calculated rotation cycle, the irradiation activating means determines whether or not the irradiation of the search wave is performed. The start timing of the irradiation unit is changed so that the azimuth angle to be started becomes constant between the scans.

As described above, according to the on-vehicle radar device of the present invention, the start timing of the irradiation unit is changed based on the actually measured rotation period of the rotation axis, and the azimuth at which the irradiation of the search wave is started between each scan. Since the angle is set to be constant, it is possible to obtain a detection result for the same irradiation range for each scan from the receiving unit that receives the search wave reflected back from an obstacle or the like. As a result, the detection results in the same direction (point) can be easily associated with each other between the scans. Therefore, the use of the apparatus enables accurate detection of an obstacle or the like.

When vehicles equipped with the same on-vehicle radar device run side by side, etc., when the search waves are emitted from both vehicles at exactly the same time, the search waves interfere with each other and normal detection cannot be performed. there is a possibility. However, in the present invention, the timing of irradiating the exploration wave always changes in accordance with the fluctuation of the rotation cycle of the rotating shaft, so that the rotating cycle of the rotating shaft fluctuates in exactly the same way between devices mounted on different vehicles. Since it is impossible, even if the irradiation timings of the search waves are temporarily coincident and interference occurs, the irradiation timing is immediately shifted, and the interference does not continue for a long time.

In the above invention, the driving timing of the irradiating means is changed according to the rotation cycle of the rotating shaft. In the vehicle-mounted radar device according to the eighth aspect, the irradiating driving means is provided with a predetermined reference. The irradiation unit is configured to be activated for each cycle, and the cycle error calculation unit calculates an actual rotation cycle of the rotation shaft calculated by the cycle calculation unit based on a detection result of the reference position detection unit; Calculate the cycle error with the reference cycle used for the drive timing of
The periodic error is output as the output of the apparatus together with the detection result of the receiving means.

In such a vehicle-mounted radar device of the present invention,
By using the detection result of the receiving means and the calculation result of the periodic error calculation means, it is possible to reliably make the detection results in the same direction (point) correspond to each other between the scans. That is, if the actual rotation period matches the reference period, the scanning area by the search wave becomes the same for each scan, but if there is a period error between the actual rotation period and the reference period, The irradiation area of the wave shifts with each scan,
The greater the periodic error, the greater the displacement of the scanning area.
In other words, as long as the periodic error is known, it is possible to specify the deviation of the scanning area. Using this periodic error, the reception result is corrected, and the periodic error is considered based on the reception result. If the reception result is handled in this way, the detection results in the same direction (point) between the scans can be reliably associated with each other.

By the way, when the search wave is irradiated at a constant irradiation interval and a predetermined number of times, the shorter the rotation period of the rotating shaft, the wider the scanning area becomes, but the detection density becomes coarser. As the length becomes longer, the scanning area becomes narrower, but the density of detection becomes higher. Therefore, in any case, good measurement having both range and accuracy cannot be performed, and the reliability of the measurement decreases. There is.

Therefore, the irradiating means includes a rotating means which is calculated by the period calculating means such that the angular width of the azimuth to which the search wave is irradiated is constant between the scans. It is desirable that the irradiation interval is changed according to the cycle. That is, specifically, for example, when the rotation cycle of the rotating shaft is shortened, the irradiation interval may be shortened accordingly.

In this case, a measurement result with uniform accuracy can always be obtained irrespective of the fluctuation of the rotation period of the rotation shaft, and stable measurement without variation can be performed. Next, in the on-vehicle radar device according to claim 1, the rotation axis is 1 /
When the scanning unit is configured to perform scanning once every m (m is an integer of 2 or more) rotations, in other words, to perform m scannings while the rotation axis rotates once, When the reference position detection means detects the reference position, the irradiation means is started after a set standby time, and thereafter, the irradiation means is started at intervals of 1 / m of the rotation cycle calculated by the cycle calculation means. What is necessary is just to comprise irradiation starting means.

In the on-vehicle radar device of the present invention thus configured, the azimuth at which the irradiation of the exploration wave is started between the scans can be surely kept constant irrespective of the fluctuation of the rotation period of the rotation shaft. it can. Further, in the vehicle-mounted radar device according to the tenth aspect, when the scanning unit is configured to perform scanning once each time the rotation axis rotates 1 / m (m is an integer of 2 or more), When the reference position detection unit detects the reference position, the irradiation unit may be configured to start the irradiation unit after a set standby time, and thereafter to start the irradiation unit at intervals of 1 / m of the reference cycle.

In the thus configured on-vehicle radar device of the present invention, when the rotation period of the rotating shaft deviates from the reference period, the azimuths at which the irradiation of the exploration wave is started between the scans are shifted at an equal rate. Therefore, the deviation can be accurately obtained, and the correspondence between the respective scans can be reliably specified.

When the reference position detecting means detects the reference position, the irradiation means is activated after a set standby time. If this waiting time is a fixed value,
Although the azimuths at which the irradiation of the search wave is started coincide between the scans performed during one rotation of the rotation axis, the direction in which the search wave is irradiated is changed as a whole in accordance with the fluctuation of the rotation axis. Will fluctuate.

Therefore, as described in claims 4 and 11,
It is desirable to provide an irradiation prohibiting unit that prohibits the irradiation unit from irradiating the exploration wave when the rotation period calculated by the period calculating unit is out of the predetermined allowable range. If such an irradiation prohibiting means is provided, the processing will not be continued in a state in which the accuracy is lowered, so that it is possible to reduce the possibility of causing erroneous determination or malfunction in various controls performed using the apparatus. Control with high safety can be realized.

The scanning means changes the irradiation direction of the search wave in accordance with the rotation angle of the rotating shaft, while the irradiation of the search wave is performed by the scanning means indirectly detected from the rotation position of the rotation shaft. Therefore, if the relationship between the rotation axis and the scanning means is deviated, the scanning range will be deviated accordingly.

Therefore, as described in claims 5 and 12,
It is desirable that the irradiation start unit is configured to be able to adjust a standby time from when the reference position is detected by the reference position detection unit to when the irradiation unit is first started. According to this, since the irradiation of the search wave can be started at an arbitrary timing, the irradiation direction of the search wave can be arbitrarily adjusted.

In particular, if the standby time is adjusted in accordance with the rotation cycle calculated by the cycle calculation means, the scanning area irradiated with the search wave can be adjusted regardless of the fluctuation of the rotation cycle of the rotating shaft. Not only the size of the area but also the absolute azimuth at which the scanning area is located can be kept constant.

As described in the sixth and thirteenth aspects, for example, a rotating polygon mirror provided with m reflecting surfaces on the outer peripheral portion and rotating together with a rotating shaft is used as the scanning means, and an exploring means is used as the irradiation means. A laser beam may be radiated as a wave, and the radiated laser beam may be arranged to be incident on the reflection surface of the rotary polygon mirror.

When the rotary polygon mirror is used as described above, if the tilt angles of the reflecting surfaces with respect to the rotation axis are different from each other, the scanning polygon may be used for each scanning. Since the scanning position is shifted in the direction perpendicular to the scanning direction according to the tilt angle, two-dimensional scanning can be performed.

[0027]

Embodiments of the present invention will be described below with reference to the drawings. [First Embodiment] FIG. 1 is a block diagram showing the overall configuration of an inter-vehicle distance control device to which the laser radar device of this embodiment is applied.

As shown in FIG. 1, the inter-vehicle distance control device 2 travels by irradiating a pulsed laser beam in the traveling direction of the vehicle and receiving reflected light returning from an obstacle or the like. A laser radar device 10 for detecting the position and relative speed of obstacles on the road and a preceding vehicle, a throttle opening sensor 50 for detecting the opening of a throttle valve for adjusting the intake air amount to the engine, and a steering angle detection Steering angle sensor 52, a vehicle speed sensor 54 that detects the traveling speed of the vehicle, a brake driver 56 that can drive the brake without operating the brake pedal, and a throttle valve that can be opened and closed regardless of the operation of the accelerator pedal Throttle drive 58, automatic transmission drive 60 capable of shifting the transmission without operating the shift lever, and control for inputting various commands A switch 64, a display 62 for displaying the setting state of various controls, a running state of the vehicle, and the like, and a known microcomputer are mainly configured to drive the laser radar device 10 and to receive a command input by the control switch 64. , And the laser radar device 10, each sensor 50,
Based on the detection signals from 52, 54, the brake driver 5
6, an inter-vehicle ECU 66 that drives the throttle driver 58 and the automatic transmission driver 60 to execute an inter-vehicle distance control process for making the inter-vehicle distance with the preceding vehicle equal to the target inter-vehicle distance.

Here, FIG. 2A is a plan view showing an arrangement of each part constituting the laser radar device 10 of the present embodiment, and FIG. 2B shows a structure around a polygon mirror which is a main part thereof. It is a side view showing. Laser radar device 1 of the present embodiment
Reference numeral 0 denotes a laser diode (LD) 12 for converting an electric signal into a laser beam in an infrared region as shown in FIGS.
A collimator lens 14 that converts the laser light emitted from the LD 12 into parallel light, a mirror 16 that reflects the laser light from the collimator lens 14 and guides the laser light in a predetermined direction,
A polygon mirror 18 for continuously changing the irradiation direction of the laser light guided by the mirror 16, a light receiving lens 20 for condensing reflected light, and a photodiode for converting a reflected wave condensed by the light receiving lens 20 into an electric signal 22.

As shown in FIG. 2, the polygon mirror 18 has six reflecting surfaces on its outer periphery. Each reflecting surface has a different inclination angle with respect to the rotation axis 19 of the polygon mirror 18. I have. Then, the laser light sent from the LD 12 passes through the collimator lens 14 to be converted into substantially parallel light, and then enters the reflecting surface of the polygon mirror 18 by the mirror 16. At this time, the reflected light from the reflecting surface is scanned in the left and right direction by the rotation of the polygon mirror 18, and is scanned while being shifted in the up and down direction every time the reflecting surface on which the laser light is incident is switched.

Further, the laser radar device 10 includes an LD driving unit 24 for driving the LD 12 according to the LD driving signal SL.
A polygon scanner motor 26 that rotationally drives the rotating shaft 19 of the polygon mirror 18, a motor drive unit 28 that drives the polygon scanner motor 26 at a constant current according to the motor drive command SM, and amplifies and waveforms the output signal from the photodiode 22. Light receiving circuit 30 for shaping and LD drive unit 2
The polygon mirror 18 is located at a predetermined rotational position, and the time measuring circuit 32 for measuring the time interval from the input of the start command SS input simultaneously with the driving of 4 to the output of the light receiving signal SR from the light receiving circuit 30. A laser position is detected by outputting a motor drive command SM, and an LD drive signal SL is output based on an origin detection signal SG from the rotation position sensor 34, thereby irradiating a laser beam, and a light receiving circuit. An arithmetic unit 38 that executes various arithmetic processes such as obtaining the position and relative speed of an obstacle or the like in front of the vehicle based on the light reception signal SR output from the unit 30 and the measurement result ST from the time measurement circuit 32. It has a drive and control system.

FIG. 7 is an explanatory view showing the principle of scanning by the polygon mirror 18. As shown in FIG. In this figure, the polygon mirror 18 is viewed from the direction along the rotation axis 19, and a reflection surface is arranged on each side of the polygon mirror 18 indicated by a regular hexagon. The polygon mirror 18 is rotated clockwise (R direction in the figure) about the rotation axis 19, and the laser light is applied to the reflection surface from above the Z axis passing through the center of the rotation axis 19. And

The angle of the reflected light 101 from the reflecting surface with respect to the incident light 102 on the reflecting surface is determined by the polygon mirror 1
8 at the point A on the reflecting surface.
As shown in FIG. 7A, the incident light 102 is reflected to the left at an angle θA, and at the point B, as shown in FIG. 7B, the incident light 102 is reflected to the right at an angle θB. I do. In other words, if the incident light 102 is applied to the section from the point A to the point B according to the rotation of the polygon mirror 18, the reflected light 101 causes the reflected light 101 to extend in the direction perpendicular to both the Z axis and the rotation axis 19. The angle θ to the left of the Z axis
A, scanning is performed on the right side in the range of the angle θB. When the section irradiated with the incident light 102 on the reflection surface changes, the scanning area also changes according to the changed irradiation section.

By the way, the laser radar device 10 is provided at a position exposed to the outside of the front of the vehicle body so as to irradiate a laser beam in the traveling direction of the vehicle and receive the reflected light. Therefore, as shown in FIG. In this figure, the LD driving unit 24, the motor driving unit 28, the light receiving circuit 3
Although not shown, the arithmetic unit 38 is mounted on the side walls of the housing H and on the boards P1 to P3 disposed below the motor drive unit 28.

The rotation position sensor 34 is provided as shown in FIG.
As shown in FIG. 2, the sensor comprises a well-known proximity sensor that magnetically detects the passage of a magnet M attached to the rotation shaft 19 of the polygon mirror 18. The magnet M has a hexagonal polygon mirror 18 whose specific apex corresponds to the rotational position sensor 3.
4 is attached to the rotation shaft 19 so that a detection signal is output from the rotation position sensor 34 when passing through the vicinity.

Next, the main processing executed by the arithmetic section 38 will be described with reference to the flowchart shown in FIG. Although not shown, the arithmetic unit 38 is provided with a first timer that always operates and indicates an absolute time, and a second timer that measures a set time.

When this process is started, first, in S100, a motor drive command SM is sent to the motor drive unit 28 to drive the polygon scanner motor 26 and rotate the polygon mirror 18. In the following S110, it is determined whether or not the origin position of the polygon mirror 18 has been detected by the rotation position sensor 34. If not detected, this step is repeated to stand by, and on the other hand, it is determined that the origin position has been detected. When it is determined, the process proceeds to S120.

In S120, the counter C for counting the number of times the second timer is started is cleared (C ← 0), and the subsequent S
In step 130, after setting the second timer so as to measure the standby time Tz set in the irradiation timing generation processing described later, the counter C is incremented in step S140 (C ← C
+1).

In the following S150, S130 or the later-described S
It is determined whether or not the second timer set at 180 has timed out, and if it has not timed out, the process waits by repeatedly executing the same step. On the other hand, if it is determined that it has timed out, Shift to S160,
A distance measurement process executed separately from this process is started.

In this distance measuring process, a pulsed LD drive signal SL is sent to the LD drive unit 24 to cause the LD 12 to emit light and perform scanning by laser light. In this embodiment, L
As a D drive signal (that is, a laser beam), a specified number N (105 in this embodiment) of pulse signals are transmitted at an irradiation interval Tp set in an irradiation timing generation process described later. At the same time as the transmission of the pulse signal, a start command SS is input to the time measuring circuit 32.
If R is detected, the measurement result ST of the time measurement circuit 32, that is, until the next pulse signal is transmitted, that is,
Based on the required time tsr [sec] from the input of the start command SS to the input of the light receiving signal SR, the distance L to the obstacle reflecting the pulse signal is calculated, and the calculation result is stored in the memory. Perform the following processing. Note that the distance L to the obstacle is L = L when the speed of light is c [m / sec].
It can be easily calculated as (tsr · c) / 2.

In the following S170, it is determined whether or not the counter C is equal to the number of reflection surfaces of the polygon mirror 18 (ie, 6 in this embodiment). If not, the flow shifts to S180 to generate irradiation timing to be described later. After setting the second timer to measure the scanning start interval Tem set in the process,
It returns to S140.

On the other hand, if an affirmative determination is made in S170, it is determined that the processing for one round of the polygon mirror 18 has been completed, and the flow returns to S110. Here, FIG. 4 is a timing chart showing the irradiation timing of the radar light by this processing.

That is, in the present processing, when it is detected from the origin detection signal SG that the polygon mirror 18 is at the origin position, the standby time Tz elapses at first, and thereafter, every time the scanning start interval Tem elapses. Then, start the ranging process,
Scanning is performed with a pulsed laser beam. Then, when the distance measurement processing is started by the number of reflection surfaces of the polygon mirror 18,
Next, the same processing is repeatedly executed after the detection of the origin position.

During a period other than the period in which the distance measurement process started in S160 is being performed, the positional relationship between the data and the distance are determined based on the distance data stored for each pulse signal by the distance measurement process. Grouping processing for judging whether or not the light is reflected from the same object based on the degree of separation, and recognizing a grouped object by grouping each data, and the distance measurement processing performed one cycle before the polygon mirror 18 Attribute determination processing, which determines whether or not the object recognized by the grouping is moving or not, also in light of the detection result of, and determines the attribute of the object such as whether the object is a roadside road sign or a vehicle. Be executed.

Next, the standby time Tz, the scanning start interval Tem,
The irradiation timing generation processing for setting the irradiation interval Tp will be described with reference to the flowchart shown in FIG. This process is executed by an interrupt process each time the rotation position sensor 34 detects the origin position of the polygon mirror 18.

When this process is started, first, in S210, the timer value t1 of the first timer, that is, the polygon mirror 1
The time at which the origin position of No. 8 is detected is read, and the subsequent S22
In the case of 0, the timer value t0 one cycle before and the rotation cycle Tm0 of the rotating shaft 19 stored when the present process was started last time are read.

In S230, a rotation cycle Tm1 (= | t0-t1 |) of the rotating shaft 19 is calculated based on the present and previous timer values t1 and t0 read in S210 and S220. In subsequent S240, whether the rotation cycle Tm1 calculated in S230 is a value within the allowable range is determined by determining whether the deviation from the reference cycle Tb (100 ms in this embodiment) is an allowable value Tth (3 ms in this embodiment). If it is within the allowable range, the above-described distance measurement processing is permitted in S250 and the process proceeds to S260. If it is determined that the distance is out of the allowable range, the process proceeds to S310. The process shifts to prohibiting the distance measurement processing and then terminating the present processing.

In S260, an average cycle Tav [s] of the past 10 cycles including the rotation cycle Tm1 measured this time is calculated by the following equation (1). Tav = (Tm0 × 9 + Tm1) / 10 (1) In the following S270, based on the calculated average period Tav, the standby from the detection of the origin position of the polygon mirror 18 to the start of the first irradiation of the exploration wave is started. Time Tz,
It is calculated by the following equation (2). Note that θz [deg]
Is the rotation angle (see FIG. 8) from the origin position of the polygon mirror 18 to the point where the exploration wave is to be irradiated first, and △ θz is the assembling error between the rotation axis 19 and the polygon mirror 18. This is represented by a rotation angle (not shown) of the polygon mirror 18.

Tz = Tav × (θz + △ θz) / 360 (2) In the following S280, as shown in the equation (3), the average period T
av is divided by the number of reflection surfaces of the polygon mirror 18 to obtain a scan start interval T, which is an interval between the start times of each scan.
Calculate em.

Tem = Tav / 6 (3) In subsequent S290, the irradiation interval Tp of the pulse signal by the distance measurement processing is calculated by the following equation (4). Note that θp
[Deg] represents the width of the scanning area by the search wave in terms of the rotation angle of the polygon mirror 18 (see FIG. 8).

Tp = Tav × θp / 360 / (N−1) (4) Finally, in S270, the previous timer value t0 and rotation cycle Tm0 are updated with the current timer value t1 and average cycle Tav. Thereafter, the present process ends. Note that, in the present embodiment, the LD 12, the LD driving unit 24, the distance measurement process, and S29
0 is irradiation means, polygon mirror 18 is scanning means, light receiving lens 20, PD22, light receiving circuit 30 is receiving means, rotational position sensor 34 is reference position detecting means, S110 to S18.
0, S270 and S280 are irradiation starting means, and S210 to S
230, S260 and S300 are cycle calculating means, S24
0, S250, and S310 correspond to irradiation prohibiting means, and the cyclic error calculation processing (S410 to S450) corresponds to cyclic error calculating means.

As described above, in the laser radar device 10 of this embodiment, the average period Tav is calculated based on the actually measured value Tm1 of the rotation period of the rotating shaft 19 (that is, the polygon mirror 18). Since 1/6 of Tav is set as the scanning start interval Tem, as shown in FIG. 8A, regardless of the fluctuation of the rotation cycle of the rotating shaft 19, the laser light is always applied to all the reflecting surfaces at the same timing. 8 is started, and as shown in FIG. 8B, scanning by any of the reflection surfaces scans within the same angle range.

As a result, the detection results in the same direction can be easily associated with each other between the scans, and a grouping process for recognizing an object by grouping the detected distance data can be performed accurately. it can. Moreover, in the laser radar device 10 of the present embodiment, the standby time Tz until the first distance measurement process is started after the detection of the origin position is:
The rotation axis 19 and the polygon mirror 1 are based on the average period Tav.
8 is set in consideration of the assembly error △ θz, regardless of the fluctuation of the rotation cycle of the rotation shaft 19.
Not only can the absolute azimuth of the scanning area be kept constant with high accuracy, but also the irradiation interval Tp of the pulse signal in the distance measurement processing is equalized within the preset angle range θp based on the average cycle Tav. Since the intervals are set so as to be set at regular intervals, the absolute width of the scanning region can be accurately and constantly maintained irrespective of the fluctuation of the rotation cycle of the rotating shaft 19.

Further, by appropriately adjusting the angle θz used for calculating the standby time Tz, the scanning area can be set to a desired azimuth. Further, in the laser radar device 10 of the present embodiment, the calculation of the standby time Tz, the scanning start interval Tem, and the irradiation interval Tp is not performed using the detected value Tm1 of the rotation cycle as it is, but based on the average rotation cycle of the past 10 cycles. Since the rotation is performed using the corresponding average period Tav, even if the rotation period fluctuates greatly due to noise or the like, a stable operation can be secured without being greatly affected by the fluctuation.

Further, the laser radar device 1 of the present embodiment
In the case of 0, when the rotation cycle greatly fluctuates out of the allowable range, the distance measurement processing is prohibited, and the processing is not continued by the detection information having deteriorated accuracy. It is possible to improve the reliability of various processes performed based on the ten detection results.

Further, in the laser radar device 10 of the present embodiment, the timing of irradiating the search wave always changes according to the fluctuation of the rotation cycle of the polygon mirror 18, so that the vehicle equipped with the same laser radar device 10 Even if interference occurs temporarily with the irradiated laser light, the irradiation timing is immediately shifted, so that the interference does not continue for a long time and the device can be used comfortably.

Then, such a laser radar device 10
The inter-vehicle distance control device 2 configured with the use of the vehicle can accurately recognize an obstacle in front of the vehicle and a preceding vehicle, so that the inter-vehicle control can be performed safely and accurately. In this embodiment, the standby time Tz and the irradiation interval Tp are variably set based on the average period Tav.
A fixed value may be set.

In this embodiment, the polygon mirror 18
Has six reflective surfaces and all the reflective surfaces are used for scanning. However, the number of reflective surfaces is not limited to this, and may be any number. In particular, when there is only one reflecting surface from the beginning, or when only one of the plurality of reflecting surfaces is used for scanning, the processing shown in the flowchart of FIG. 3 is performed in steps S120, S140, S170, and S180.
May be deleted, and after processing in S160, the process may return to S110. [Second Embodiment] Next, a second embodiment will be described.

The laser radar device according to the present embodiment has a
8 differs only in a part of the processing, and only the different part will be described. That is, in this embodiment,
The standby time Tz, the scanning start interval Tem, and the irradiation interval Tp are calculated using the reference cycle Tb (100 ms in this embodiment) instead of the average cycle Tav in the above equations (2) to (4). This is a fixed value, and a rotation cycle error calculation process is executed instead of the irradiation timing generation process.

The rotation cycle error calculation processing will be described with reference to the flowchart shown in FIG. This process is executed by the interrupt process each time the rotation position sensor 34 detects the origin position of the polygon mirror 18.
When the present process is started, first, in S410, the timer value t1 of the first timer is read, and in the next S420, the timer value t one cycle before that stored when the present process was started last time is read.
0, and at S430, S210, S22
The current and previous timer values t1, t0 read at 0
, The rotation period Tm1 of the rotation shaft 19 (= | t0−t
1 |) is calculated.

At S440, a cycle error ΔTm (= Tm1−Tb) between the reference cycle Tb, which is the basis of the times Tz and Tem, and the actual rotation cycle Tm1, is calculated.
After updating the previous timer value t0 with the current timer value t1, the present process is terminated. That is, in this processing, the rotation axis 1
If the rotation cycle of the polygon mirror 9 (that is, the polygon mirror 18) fluctuates and does not coincide with six times the scanning start interval Tem, the position where the laser light is irradiated is different for each reflection surface of the polygon mirror 18, and FIG. As shown in FIG. 9B, the reflected light from each reflecting surface scans an area slightly shifted in the scanning direction, and the periodic error ΔTm corresponding to the shift amount of the scanning area. Has been detected.

For this reason, according to the present embodiment, before performing the grouping process, the position information of the detection result is corrected by using this cyclic error ΔT, or at the time of the grouping process,
Selection of the detection results to be compared with each other is determined by this periodic error ΔT
By taking into account the shift amount of the scanning region converted from m, even if the scanning region is shifted, the respective detection results can correspond to each other accurately. As in the first embodiment, the grouping process is performed. , It is possible to accurately detect obstacles and the like.

In the present embodiment, the distance measurement process is not prohibited even if the rotation cycle greatly fluctuates.
S240, S250, and S310 shown in the irradiation timing generation processing are inserted after S440 of the cycle error calculation processing, and the distance measurement processing is prohibited when the fluctuation of the rotation cycle is large, as in the first embodiment. May be configured.

In this embodiment, the standby time Tz and the irradiation interval Tp are also fixed values. However, as in the first embodiment, they are variably set based on the average period Tav. Is also good. Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and can be implemented in various modes.

For example, in the above-described embodiment, the polygon mirror 18 is used as the scanning means. However, the scanning direction of the search wave may be changed according to the rotation angle of the rotating shaft driven by the motor. The search wave is not limited to a laser beam, and a millimeter wave or the like may be used.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a laser radar device of an embodiment and an inter-vehicle distance control device to which the laser radar device is applied.

FIGS. 2A and 2B show an arrangement of each part constituting the laser radar device, wherein FIG. 2A is a plan view and FIG. 2B is a side view near a polygon mirror.

FIG. 3 is a flowchart illustrating a main process executed by a calculation unit.

FIG. 4 is a timing chart showing the irradiation timing of radar light.

FIG. 5 is a flowchart illustrating irradiation timing generation processing executed by a calculation unit.

FIG. 6 is a flowchart illustrating a rotation cycle error calculation process executed by a calculation unit.

FIG. 7 is an explanatory diagram illustrating a principle of scanning of a laser beam by a polygon mirror.

FIG. 8 is an explanatory diagram illustrating an operation at the time of scanning and a scanning area in the present embodiment.

FIG. 9 is an explanatory diagram showing a problem of the conventional device.

[Explanation of symbols]

2 ... inter-vehicle distance control device 10 ... laser radar device 12 ... laser diode (LD) 14 ... collimating lens 16 ... mirror 18 ... polygon mirror 19 ... rotation axis 20 ... light receiving lens 22 ... photodiode (PD)
24 LD drive unit 26 Polygon scanner motor 28 Motor drive unit 30 Light receiving circuit 32 Time measuring circuit 34 Rotational position sensor 38
... Calculation unit 50 ... Throttle opening degree sensor 52 ... Steering angle sensor
54 ... vehicle speed sensor 56 ... brake drive 58 ... throttle drive 60 ... automatic transmission drive 62 ... display 64 ... control switch 66 ... vehicle ECU

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI G01S 13/93 G01S 13/93 Z (72) Inventor Hiroshi Niimi 1-1-1, Showa-cho, Kariya-shi, Aichi Pref. (72) Inventor Toshifumi Nozawa 1-1-1, Showa-cho, Kariya-shi, Aichi Prefecture Inside DENSO Corporation

Claims (14)

[Claims] 1. A rotating shaft driven by a motor, an irradiating means for irradiating a search wave at a fixed irradiation interval and a predetermined number of times, and a search irradiating by the irradiating means according to a rotation angle of the rotating shaft. Scanning means for changing the direction of wave irradiation along a predetermined scanning direction; receiving means for receiving an exploration wave reflected back to the object; and that the rotational position of the rotating shaft is at a specific reference position. A reference position detecting means for detecting, and an irradiation starting means for repeatedly starting the irradiation means based on a timing at which the reference position detecting means detects the reference position; In the radar device, a cycle calculation unit that calculates a rotation cycle of the rotation shaft based on a detection result of the reference position detection unit is provided, and the irradiation start unit includes: So they azimuth initiated is constant between each scan, vehicle radar apparatus characterized by varying the start timing of the irradiation unit in accordance with the rotation period calculated by said period calculating means. 2. The irradiation unit changes the irradiation interval according to a rotation period calculated by the period calculation unit such that a scanning area width irradiated with the search wave is constant between each scan. The on-vehicle radar device according to claim 1, wherein: 3. The scanning unit according to claim 2, wherein the rotation axis is 1 / m
(M is an integer of 2 or more) scans once every rotation, and the irradiation starting unit starts the irradiation unit after a set standby time when the reference position detection unit detects the reference position, 3. The on-vehicle radar device according to claim 1, wherein the irradiation unit is activated at intervals of 1 / m of a rotation period calculated by the period calculation unit. 4. When the rotation cycle calculated by the cycle calculation means is out of a preset allowable range,
The on-vehicle radar device according to claim 3, further comprising an irradiation prohibiting unit that prohibits the irradiation of the search wave by the irradiation unit. 5. The on-vehicle radar device according to claim 3, wherein the irradiation start unit is configured to adjust the standby time. 6. The scanning means comprises a rotating polygonal mirror provided with m reflecting surfaces on an outer peripheral portion and rotating together with the rotation axis, and the irradiating means irradiates a laser beam as a search wave and irradiates the laser beam. The on-vehicle radar device according to any one of claims 3 to 5, wherein the laser beam is disposed so as to be incident on a reflection surface of the rotary polygon mirror. 7. The rotary polygon mirror according to claim 6, wherein each of the reflecting surfaces has a different inclination angle with respect to the rotation axis, and is configured to be capable of two-dimensional scanning. In-vehicle radar device. 8. A rotating shaft driven by a motor, an irradiating means for irradiating a search wave at a fixed irradiation interval and a predetermined number of times, and a search irradiating the irradiating means according to a rotation angle of the rotating shaft. Scanning means for changing a wave irradiation direction along a predetermined scanning direction; receiving means for receiving a search wave reflected back from an object; and detecting that the rotational position of the rotation axis is at a specific reference position. Reference position detecting means for activating the irradiating means for every predetermined reference period based on the timing of detecting the reference position by the reference position detecting means. A cycle calculating means for calculating a rotation cycle of the rotating shaft based on a detection result of the reference position detecting means, wherein the cycle calculating means calculates A cyclic error calculating means for calculating a cyclic error between the rotational cycle and the set cycle, based on the rotational cycle to be performed, and providing the calculation result by the cyclic error calculating means together with the detection result by the receiving means. An on-vehicle radar device characterized by the output of the device. 9. The irradiation unit changes the irradiation interval according to a rotation cycle calculated by the cycle calculation unit such that an angular width of an azimuth to which the search wave is irradiated becomes constant between scans. The vehicle-mounted radar device according to claim 8, wherein: 10. The scanning means, wherein the rotation axis is 1 / m
(M is an integer of 2 or more) scans once every rotation, and the irradiation starting unit starts the irradiation unit after a set standby time when the reference position detection unit detects the reference position, 10. The on-vehicle radar device according to claim 8, wherein the irradiation unit is activated at intervals of 1 / m of the reference period. 11. An irradiation prohibition unit for prohibiting irradiation of a search wave by said irradiation unit when a rotation period calculated by said period calculation unit is out of a preset allowable range. The on-vehicle radar device according to claim 10, wherein: 12. The irradiation start unit according to claim 10, wherein the standby time is adjustable.
Or an in-vehicle radar device according to claim 11. 13. The scanning means comprises a rotating polygon mirror having m reflecting surfaces on an outer peripheral portion and rotating with the rotation axis, and the irradiating means irradiates a laser beam as a search wave and irradiates the laser beam. 13. The on-vehicle radar device according to claim 110, wherein the laser beam is arranged to be incident on a reflection surface of the rotary polygon mirror. 14. The rotating polygon mirror according to claim 13, wherein each reflecting surface has a different inclination angle with respect to the rotation axis, and is configured to be capable of two-dimensional scanning. In-vehicle radar device.