JP2008286767A - Space measuring device for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a space measuring device for a vehicle, inexpensive and improved in measuring accuracy. <P>SOLUTION: This space measuring device for a vehicle, which is loaded on a vehicle to measure a predetermined space in the neighborhood of one's own vehicle, includes: a distance measuring means configured to emit a fan-beam shaped laser pulse rays having an elliptic section elongated substantially in the vertical direction from the longitudinal rear end part of the own vehicle toward the substantially horizontal right-hand direction and the substantially horizontal left-hand direction, and measure the time of flight, thereby measuring a distance to a peripheral object existing in right and left areas at the back of the own vehicle; and a space measuring means for measuring a space existing at the back of the own vehicle from the distance to the peripheral object measured by the distance measuring means, an average value of wheel speed pulses of a rear wheel and a turning angle of a steering wheel. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention generally relates to a vehicle space measurement device that is mounted on a vehicle and measures a predetermined space around the host vehicle, and more particularly to a vehicle space measurement device that is low-cost and has improved measurement accuracy.

  Conventionally, an apparatus for measuring a predetermined space is known (for example, see Patent Documents 1 to 4).

  Patent Document 1 states that “a laser beam is a fan-shaped beam that spreads in only one direction (usually the vertical direction) and is scanned in a direction (usually a horizontal direction) perpendicular to the direction in which the laser beam is spread. By irradiating and receiving the reflected light, “the time required to scan and measure one screen compared to two-dimensional scanning in both vertical and horizontal directions as a spot-like laser beam” is significantly reduced. And a moving object measuring apparatus aimed at simplifying the scanning mechanism is disclosed (see paragraph 0015).

  According to Patent Document 2, “distance and azimuth data to surrounding objects by a distance measuring device is collected by a line segment extracting unit from a data point sequence sequentially accumulated as a set together with data of the own vehicle position obtained by the own vehicle position detecting device. While the line segment is extracted, the direction of travel when the straight traveling determination unit determines that the vehicle is traveling straight is set as the reference direction, and the noise removal unit has a predetermined angle relationship from the line segment extracted by the line segment extraction unit to the reference direction. A surrounding object recognizing device aimed at “determining the position of surrounding objects with high accuracy” is disclosed (see paragraph 0014).

  Patent Document 3 states that “a beam having a predetermined divergence angle is sequentially emitted toward a plurality of different directions, and a reflected wave from an obstacle in each direction is received, whereby the radiation angle of the beam for each direction is obtained. Based on the obstacle detection unit that detects an obstacle existing in the range, and the received signal of the reflected wave for each direction output from the obstacle detection unit, between the obstacle and the own vehicle in each direction The distance calculation unit that calculates the representative distance, and the distance for each azimuth calculated by the distance calculation unit as the image creation reference, expands two-dimensionally within the radiation angle range of the beam emitted in each azimuth. An obstacle image creating unit that creates an obstacle image as an obstacle image, generates and outputs image data for displaying the obstacle image, and image data created by the obstacle image creating unit. To receive, and a display unit for displaying an image showing the positional relationship between the obstacle and the own vehicle "was obstacle detection apparatus is disclosed (see page 4, line 8 to line 17).

In Patent Document 4, “the sensor is installed on the side surface of the wheel so that the detection area rotates with the rotation of the wheel”, and “the vehicle travels and the wheel rotates, the detection area of the sensor is expanded. A vehicle surroundings monitoring device aimed at making it possible to monitor a wide area around the vehicle with a single sensor is disclosed (see paragraph 0021).
Japanese Patent Laid-Open No. 5-113481 JP 2002-228734 A International Publication No. 2004/083889 Pamphlet JP 2006-007907 A

  When ranging from stereo images, if the brightness of the surrounding environment is very large (for example, a vehicle with a headlight turned on at night or a convenience store open 24 hours a day) Since the disturbance is large, the dynamic range of the image sensor is insufficient and distance measurement may be difficult.

  In addition, when there is a parked vehicle with the outer plate surface as clean as the mirror surface, distance measurement is performed on the image reflected on the surface, making it difficult to measure the distance to the parked vehicle. obtain.

  In addition, when a scan type laser radar is used, since a movable mechanism called a scan mechanism is required, relatively high reliability is required and a relatively high cost is required as compared with a case where a movable mechanism is not required.

  Further, since the laser light is spot light, distance measurement can be difficult when the reflectance of the light-reflected portion in the peripheral object is low. In this case, it is conceivable to provide a plurality of measurement points on the same vertical line to compensate, but the effect cannot be reduced unless the energy emitted at one point is increased. Considering the influence on the vehicle, it is not suitable for a light emitting object in a low-speed moving body such as a vehicle to be parked.

  The present invention has been made to solve such problems, and it is a main object of the present invention to provide a vehicle space measurement device that is low in cost and improved in measurement accuracy.

  One aspect of the present invention for achieving the above object is a vehicle space measurement device that is mounted on a vehicle and measures a predetermined space around the host vehicle, and is substantially horizontal right from the rear end in the front-rear direction of the host vehicle. In the left and right areas behind the vehicle by emitting a fan-beam shaped laser pulse light having a vertically long elliptical cross section in the vertical direction and in the horizontal direction, and measuring the time of flight. From the distance measuring means for measuring the distance to the existing surrounding object, the distance to the surrounding object measured by the distance measuring means, the average value of the wheel speed pulse of the rear wheel, and the steering wheel steering angle, A space measuring device for a vehicle having space measuring means for measuring a space existing behind the vehicle.

  In the above aspect, the distance measuring unit uses, for example, an anamorphic lens or a cylindrical lens to form the laser pulse light into a fan beam shape having an elliptical cross section that is vertically long in a substantially vertical direction.

  According to the above aspect, when the host vehicle is parked while moving backward, the vehicle does not use a distance measuring device that requires a movable mechanism such as a scan type laser radar, and the vehicle moves rearward according to the backward movement of the host vehicle. Since a wide parking space can be measured, space measurement at a lower cost is realized.

  Further, according to the above aspect, since the laser pulse light has a vertically long fan beam shape in the substantially vertical direction, the probability of obtaining reflected light can be greatly increased compared to the case of using spot light. Since the N ratio is improved, more accurate spatial measurement is realized.

  In the above aspect, in order to reduce the number of parts, the distance measuring unit uses a prism to diverge and emit laser pulse light emitted from one light source in a substantially horizontal right direction and a substantially horizontal left direction. It is preferable.

  In this case, in order to identify whether the reflected light is emitted in the left or right direction, the distance measuring means transmits the laser pulse light emitted in the substantially horizontal right direction and the substantially horizontal left direction. It is desirable to bend one of the light polarization planes using an optical element (for example, bend 90 ° using a half-wave plate).

  According to the present invention, it is possible to provide a vehicle space measurement device that is low in cost and has improved measurement accuracy.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to the accompanying drawings.

  Hereinafter, a vehicle space measurement device according to an embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 is a schematic configuration diagram of a vehicle space measurement apparatus 100 according to the present embodiment.

  The space measurement device 100 emits laser pulse light, receives the reflected light, and measures the time of flight (TOF) until it returns after being reflected by a surrounding object, and the rear of the vehicle. And a calculation unit 102 that executes a calculation for measuring the parking space (which will be described in detail later with reference to FIG. 6).

  In the present embodiment, the rear 101 wheels are transmitted to the sensor 101 from a wheel speed sensor (not shown). In this embodiment, the sensor 101 emits laser pulse light a predetermined number of times (for example, 10 times) for each pulse of the rear two wheels, and obtains an average value of TOF obtained in each light emission by one measurement. It shall be treated as a TOF.

  Further, the TOF measured from the sensor 101 is transmitted to the calculation unit 102, the steering angle of the steering wheel is transmitted from a steering angle sensor (not shown), and the rear two-wheel pulse is transmitted from a wheel speed sensor (not shown). The

  When the space measuring device 100 is mounted on the vehicle V, the sensor 101 is provided at a rear end portion in the front-rear direction of the vehicle V as shown in FIG. It is mounted in an exposed state.

  2 and 3 are diagrams for explaining the beam shape of the laser pulse light emitted from the sensor 101 in this embodiment. FIG. 1 is a top view seen from directly above, and FIG. FIG.

  As shown in FIG. 2, in this embodiment, the sensor 101 emits laser pulse light B polarized in a direction substantially horizontal to the ground from the rear end of the vehicle V in both the right direction and the left direction of the vehicle V. .

Laser pulse light B _L emitted laser pulse beam B _R and leftward are fired in the right direction is fired in a direction substantially orthogonal to the longitudinal direction of the vehicle V respectively, and, substantially on the ground Since the light is emitted horizontally, it can be said that they do not interfere with each other.

Further, as shown in FIG. 3, the laser pulse lights _BR and _BL emitted from the center 101 are light emission in the shape of a sector beam having a vertically long elliptical cross section in a substantially vertical direction with respect to the ground.

  By making the beam shape of the laser pulse light for distance measurement into the fan-shaped beam shape as described above, the irradiation area can be expanded without increasing the number of pulses as compared with the case of hitting the spot light. Even in an object with a small amount (or a large area area with low reflectivity), the probability that reflected light can be obtained from any point / area in the irradiated area is greatly increased, and thus the S / N ratio is improved. Accurate ranging is possible.

4 and 5 are schematic configuration diagrams of the sensor 101. FIG. 4 shows a state when the laser pulse lights B _R and B _{L are} emitted, and FIG. 5 shows a state when the reflected light B _R 'B _L ' is received. Show.

Sensor 101 has a single laser emission units 401, and two light receiving portions 402 and 403 (right reflected light _{B R} 'light receiving portion 402 and the left reflected light _{B L'} light receiving portion 403), the.

  The laser light emitting unit 401 includes an optical system (not shown) for making the beam shape of the emitted laser pulse light into a fan beam shape as described above. This optical system is, for example, an anamorphic lens (afocal lens) which has a cylindrical shape and expands and emits incident light only in one direction) or a cylindrical lens. (Cylindrical lens) is used to enlarge only the direction perpendicular to the ground.

  The sensor 101 further reflects the optical path of the laser pulse light emitted from the laser light emitting unit 401 inside and bends 90 ° in the left and right directions, and bends the reflected light of the laser pulse light incident from the outside by 90 °. The optical prism 404 is directed toward the light receiving portions 402 and 403.

The sensor 101 further includes a half-wave plate 405 disposed on the optical path for only one of the left and right laser pulse lights. In this embodiment, as an example, it is assumed that the half-wave plate 405 is placed only on the optical path of the laser pulse beam B _R in the right direction.

Half-wave plate 405, bend light polarization plane of the laser pulse beam _{B R} 90 °. Thus, right reflected light B _{R 'light} receiving unit 402, the received light, the reflected light B _R of the laser pulse light B _R emitted to the _right' laser or a, or emitted to the left It becomes possible to easily identify whether the reflected light B _L ′ of the pulsed light B _L is present. Similarly, by providing the half-wave plate 405, the light receiving unit 403 for the left reflected light B _L ′ also determines whether the received light is the reflected light B _L ′ of the laser pulse light B _L emitted in the left direction. or whether it is reflected light B _{R 'of} the laser pulse light B _R emitted to the right, it becomes possible to easily identify.

  FIG. 6 shows the state of the space measurement process executed in the calculation unit 102 (FIG. 1). Here, a case where the host vehicle V is going to park in reverse in the space between the parked vehicles P1, P2, P3, and P4 is taken as an example.

  First, the calculation unit 102 obtains the movement path 601 of the rear wheel shaft center position O from the average value of the rear two-wheel pulse and the steering wheel steering angle.

  In addition, the calculation unit 102 obtains a distance 602 to the left obstacle and a distance 603 to the right obstacle at each measurement point from the left and right TOFs obtained from the sensor 101.

  By plotting and connecting the points of the distance 602, the left boundary line 604 of the space extending behind the host vehicle can be estimated. Similarly, by plotting and connecting points of distance 603, it is possible to estimate the right boundary line 605 of the space extending behind the host vehicle.

  Thereby, since the left and right boundary lines of the parking space spreading behind the host vehicle V are estimated, the measurement of the parking space is realized.

  Thus, according to the present embodiment, in view of the fact that the host vehicle moves backward during parking, the host vehicle is parked without using a distance measuring device that requires a movable mechanism such as a scanning laser radar. Ranging that requires a moving mechanism by checking the boundary line of the left and right space, that is, the position where the object exists at every predetermined distance (every wheel pulse) as it moves little by little Compared to the case of using the device, it is possible to measure a parking space extending behind the host vehicle at a relatively low cost.

  Further, as described above, according to the present embodiment, the laser pulse light that is a spot light is used by making the beam shape of the laser pulse light into a fan-shaped beam shape having a vertically long elliptical cross section in the vertical direction. Compared to, it becomes possible to perform distance measurement with higher accuracy with less pulsed light.

  In the above embodiment, as an example, the TOF is calculated by the sensor 101 and this TOF is input to the calculation unit 102. However, as will be apparent to those skilled in the art, the present invention is It is not limited to the embodiment. For example, the TOF calculation may be performed on the calculation unit 102 side, or the calculation to convert the TOF into a distance is performed on the sensor 101 side, and the distance to the surrounding object is transmitted to the calculation unit 102. May be.

  In the description of the above embodiment, as an example, the host vehicle V is depicted as a right-hand drive vehicle in FIG. 3, but as will be apparent to those skilled in the art, the application of the present invention is limited to right-hand drive vehicles. This is equally applicable to left-hand drive vehicles.

  The present invention can be used for a vehicle space measurement device. The power source type, fuel type, appearance design, weight, size, running performance, etc. of the vehicle to be mounted are all unquestioned.

1 is a schematic configuration diagram of a vehicle space measurement device according to an embodiment of the present invention. It is a top view which shows the beam shape of the laser pulse light emitted by the vehicle space measuring device which concerns on one Example of this invention. It is a perspective view which shows the beam shape of the laser pulse light emitted by the vehicle space measuring device which concerns on one Example of this invention. It is a schematic block diagram of the sensor of the vehicle space measuring device which concerns on one Example of this invention. It is a schematic block diagram of the sensor of the vehicle space measuring device which concerns on one Example of this invention. It is a figure which shows the mode of the space measurement process by the calculating part of the space measuring device for vehicles which concerns on one Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Vehicle space measuring device 101 Sensor 102 Calculation part 401 Laser light emission part 402,403 Light receiving part 404 Optical prism 405 Half-wave plate

Claims (5)

A vehicle space measurement device that is mounted on a vehicle and measures a predetermined space around the host vehicle,
From the rear end in the front-rear direction of the host vehicle, a laser beam beam with a fan beam shape having a vertically long elliptical cross section in a substantially vertical direction is emitted from the rear end in the horizontal direction to the substantially horizontal left direction, and the time of flight Ranging means for measuring the distance to the surrounding objects existing in the left and right areas behind the host vehicle by measuring
Space measuring means for measuring a space existing behind the host vehicle from the distance to the surrounding object measured by the distance measuring means, the average value of the wheel speed pulses of the rear wheels, and the steering angle of the steering wheel; A vehicle space measurement device comprising: The vehicle space measurement device according to claim 1,
The vehicle distance measuring device according to claim 1, wherein the distance measuring unit uses an anamorphic lens or a cylindrical lens to form the laser pulse light into a fan beam shape having a vertically long elliptical cross section in a substantially vertical direction. The vehicle space measurement device according to claim 1 or 2,
The vehicle distance measurement device according to claim 1, wherein the distance measuring unit uses a prism to diverge and emit laser pulse light emitted from one light source in a substantially horizontal right direction and a substantially horizontal left direction. The vehicle space measurement device according to claim 3,
The vehicle distance measurement characterized in that the ranging means bends one of the light polarization planes of the laser pulse light emitted toward the substantially horizontal right direction and the substantially horizontal left direction using an optical element. apparatus. The vehicle space measurement device according to claim 4,
The vehicular space, wherein the optical element is a half-wave plate that bends one of the light polarization planes of the laser pulse light emitted toward a substantially horizontal right direction and a substantially horizontal left direction by 90 °. Measuring device.

Images