JPH05196720A - Optical-axis adjusting apparatus for laser radar in vehicle-interval-distance detecting and alarming apparatus - Google Patents

Abstract

PURPOSE:To obtain the optical-axis adjusting apparatus of the laser radar in a vehicle-interval-distance detecting and alarming apparatus, which can adjust the optical axis readily and accurately. CONSTITUTION:A visual-light emitting part 31 is provided in a laser radar unit 1. When an optical axis adjusting mode is selected by the turning of a switch and the like, the power-reduced laser beam is emitted from a laser-beam emitting part 2 of the laser radar unit 1. At the same time, visual light is emitted from the visual-light emitting part 31. The visual light is cast on a reflecting plate at the front side. With the illuminated position as a mark, the optical axis of the laser radar unit 1 can be adjusted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical axis adjusting device for a laser radar in an inter-vehicle distance detecting / warning device using laser light.

[0002]

2. Description of the Related Art The causes of rear-end collisions caused by trucks are mainly
The majority of the drivers are dozing driving and aimless driving.
Under such circumstances, an inter-vehicle distance detection / warning device has now been developed that detects the inter-vehicle distance between the own vehicle and the preceding vehicle, and issues an alarm to the driver when the distance falls below a certain distance. ing.

The outline of the current state of the art is that the laser light emitted from the light emitting portion of the laser radar unit is emitted forward from the vehicle and the laser light reflected by the reflector on the rear surface of the front vehicle is received. The light is received by the control unit, and the inter-vehicle distance is calculated in the control unit from that time,
When the inter-vehicle distance becomes smaller than the braking distance and the free running distance of the own vehicle, the buzzer in the passenger compartment is sounded.

In order to ensure safety, the laser radar unit of the inter-vehicle distance detecting / warning device as described above has an operating condition that the vehicle speed detected by the vehicle speed sensor is equal to or higher than a predetermined speed (for example, 30 km / h). Is becoming

On the other hand, at the time of shipment of a vehicle having the above-described inter-vehicle distance detecting / warning device, the optical axis of the laser beam emitted from the laser radar unit must be adjusted. That is, it is necessary to adjust the installation position of the light emitting portion of the laser light so that the laser light is emitted from the laser radar unit in parallel to the center line in the longitudinal direction of the vehicle and forward substantially horizontally in a predetermined manner. For this reason, conventionally, when the optical axis of the laser radar unit is adjusted when the vehicle is stopped, it is equivalent to the vehicle speed of 30 km / h or more of the output signal of the vehicle speed sensor that indicates the vehicle speed by the number of pulses generated per unit time. A multi-pulse pseudo vehicle speed signal is generated to adjust the position of the laser unit in a pseudo traveling state.

[0006]

As described above, in adjusting the optical axis of the laser beam in the prior art, a complicated pseudo vehicle speed signal must be separately generated and supplied, so that the optical axis adjusting operation is complicated. In addition, the laser radar unit emits full-power laser light, which causes a problem that the laser light reflected on each part in the factory interferes with the adjustment.

As a conventional optical axis adjusting device for a laser radar, as disclosed in Japanese Utility Model Publication No. 63-46855, an oscillator for generating a visible light laser is provided on the side surface of a vehicle when adjusting the optical axis. Then, the position of the vehicle is adjusted by applying a visible light laser from this oscillator to the board, and then the optical axis is adjusted by the laser light.

However, according to this method, it is not easy to accurately mount the visible light laser oscillator on the side surface of the vehicle, and since it is considered that full power laser light is used, adjustment work by the reflected laser light is required. Interference cannot be denied.

[0009]

The structure of the present invention for solving the above problems is such that when the vehicle speed detected by the vehicle speed sensor is equal to or higher than a predetermined value, the laser light emitted from the laser radar unit of the own vehicle is reflected by the preceding vehicle. Then, the time until returning to the vehicle is detected and the inter-vehicle distance is calculated.If the inter-vehicle distance becomes smaller than the safe inter-vehicle distance defined based on the braking distance of the vehicle and the free running distance, an alarm is issued. An optical axis adjusting device for a laser radar in an inter-vehicle distance detecting / warning device having a control unit, wherein a visible light emitting portion is provided in a laser light emitting portion of the laser radar unit, and a switch means is turned on to control the vehicle. Even when it is stopped, the power-down laser light is emitted from the laser light emitting portion, and the visible light is emitted from the visible light emitting portion.

[0010]

According to the optical axis adjusting device of the laser radar having the above-described structure, the optical axis of the laser beam can be adjusted by using the visible light emitted from the position close to the laser beam as a guide. Is greatly improved. Further, since the laser light emitted by turning on the switch means is powered down, the components reflected by the various parts of the factory and becoming noises for adjustment are sufficiently attenuated.

[0011]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 shows a schematic configuration of an inter-vehicle distance detecting / warning device that realizes an embodiment of the present invention, and FIG. 2 shows an outline of a mounting positional relationship with respect to the vehicle.

A laser radar unit 1 includes a light emitting portion 2 and a light receiving portion 3. The structure of the laser radar unit 1 is shown in FIG. 3. The light emitting unit 2 in the laser radar unit 1 is composed of a laser diode drive circuit 4, a laser diode 5, and a light emitting lens 6, and emits a laser beam 16 in a pulsed form at regular intervals. It emits light.
The light receiving unit 3 includes a light receiving lens 7 that receives the laser light 16 reflected by the reflector of the front vehicle, a photodiode 8, an amplifier 9, a signal processor 10, and the like. From the time difference Δt between the light emission by the light emitting unit 2 and the light reception by the light receiving unit 3, the distance detection circuit 11 detects the inter-vehicle distance D (= (Δt /
2) x speed of light) is required.

In the laser radar unit 1 according to the present invention, a light emitting portion 31 for the visible light 35 is provided for adjusting the optical axis in the vicinity of the light emitting portion 2 for the laser light 16.
As the light emitting unit 31, for example, a visible light laser diode or the like is used. In this embodiment, the visible light emitting portion 31 is provided immediately below the laser light emitting portion 2, but the position is not limited as long as it is close to the laser light emitting portion 2.
In FIG. 3, 32 is a laser diode that emits visible light,
Reference numeral 33 is a drive circuit thereof, and 34 is a lens.

The inter-vehicle distance signal, which is the detection value of the laser radar unit 1, is incorporated in the underside of the seat 13 of the truck 12 and is a control unit 14 as a control system.
Entered in. The laser radar unit 1 is assembled in the bumper 15 of the truck 12 as shown in FIG.

A vehicle speed sensor 17 is adapted to detect the vehicle speed from the rotating portion of the transmission or the like. The detection signal of the vehicle speed sensor 17 is input to the control unit 14. Reference numeral 18 denotes a steering sensor having a disc 19 provided in the steering column and a light emitting / receiving portion 20 for detecting the slit thereof, and a steering angle signal which is a detection signal thereof is inputted to the control unit 14. There is.

Reference numeral 23 denotes a wiper switch which functions as an example of an environment sensor, and ON / OFF signals of the wiper switch are input to the control unit 14. That is, when the wiper switch 23 is turned on, it is determined that it is raining.

As the other environment sensor 24, a raindrop sensor, a road surface sensor (G sensor), a temperature sensor, a slip sensor, etc. are equipped. According to the raindrop sensor, it is detected that it is raining, that is, the road surface is wet,
The road surface sensor detects whether the road surface is a turning road or other conditions, and the temperature sensor detects weather and eventually road surface conditions such as a frozen state in combination with the detection results of other sensors. The slip sensor detects whether or not the road surface is likely to slip, that is, whether the road is a low μ road or a high μ road, based on the difference in rotational speed between the front wheels and the rear wheels. The detection result is input to the control unit 14.

Reference numeral 21 denotes a display unit incorporated in the instrument panel in front of the driver's seat, which is provided with a display unit for the inter-vehicle distance, a buzzer for issuing an alarm, a ramp for blinking when an alarm is issued, etc. to alert the driver, It also warns you.

Next, the calculation process leading to the alarm generation by the apparatus of this embodiment will be described. Own vehicle 1 as shown in FIG.
The distance between the vehicle 2 and the front vehicle 22, that is, the inter-vehicle distance D (m) is obtained by the laser radar unit 1 as described above.
The vehicle speed Vf (m / s) is detected by the vehicle speed sensor 17. The speed Va (m / s) of the front vehicle 22 is calculated by a change in the inter-vehicle distance D per minute time. That is, the front vehicle speed Va is obtained from the relative speed between the own vehicle 12 and the front vehicle 22.

On the other hand, the time until the driver determines that the driver is in danger and depresses the brake pedal, that is, the free running time Td (s), the time when the driver determines that it is dangerous, that is, the determination time Tx (s) and The vehicle deceleration α ₁ (m / s ² ) and the preceding vehicle deceleration α ₂ (m / s ² ) are stored in advance in the memory of the control unit 14. The decelerations α ₁ and α ₂ are stored as values assuming full braking, and normally α ₁ = α ₂ .

The braking distance L ₁ of the front vehicle 22 can be obtained from the front vehicle speed Va and the deceleration α ₂ as L ₁ = Va ² / 2α ₂ .

The free running distance L ₂ of the vehicle 12 is determined by the vehicle speed Vf.
From the free running time Td and the judgment time Tx, L ₂ = (Td +
Tx) Vf.

The braking distance L ₃ of the vehicle 12 is determined by the vehicle speed Vf.
And deceleration rate α ₁ , L ₃ = Vf ² / 2α ₁ .

Therefore, as a condition for generating an alarm, the sum of the front vehicle braking distance L ₁ and the inter-vehicle distance D is the automatic braking distance L ₃
And when it becomes smaller than the sum of the vehicle free running distance L ₂ . That is, Va ² / 2α ₂ + D <Vf ² / 2α ₁ + (Td + Tx) Vf Therefore, D <(Td + Tx) Vf + (Vf ² / 2α ₁ -Va ² / 2α ₂ )
= Ds (safe inter-vehicle distance), the buzzer incorporated in the display unit 21 issues an alarm and the lamp blinks.

As can be seen from this equation, the safe inter-vehicle distance D
Since the speed of the front vehicle 22 is taken into consideration when calculating s, the front vehicle 2
The optimum alarm time is determined by whether the vehicle 2 is running at high speed or low speed, whether it is accelerating or decelerating, and whether it is stopped. When the front vehicle 22 is stopped, Va = 0 in the equation.

The decelerations α ₁ and α ₂ of the vehicle are small on a wet road surface or a frozen road surface in the case of rain. Therefore, when it is detected that the wiper switch 23 is turned on, the control unit 14 causes the decelerations α ₁ , α ₂
Change the value of to change the distance between alarms. That is, on a wet road surface or the like, the safe inter-vehicle distance Ds automatically changes, and the alarm generation time is advanced. For example,
If the deceleration α ₁ (= α ₂ ) on the dry road is about 0.3 G, 0.2 G (for example, wet road surface) depending on the road surface condition,
Change to 0.1G (for example, frozen roads, snow roads, etc.).

Next, a specific control example by the control unit 14 in the apparatus of this embodiment will be described with reference to the flowchart of FIG. This example is the most basic one. First, initial values are set in step (1). That is, the idle time Td, the judgment time Tx, the decelerations α ₁ and α ₂ (α ₁ = α ₁ = when the vehicle 12 and the front vehicle 22 are fully braked)
α ₂ ) is set.

Next, it is judged whether or not it is in the optical axis adjustment mode (step (2)). Whether or not this mode is set is determined by, for example, whether or not the switch 14a is turned on.
When it is determined that the vehicle is not in the optical axis adjustment mode, it is next determined whether the vehicle speed is 30 km / h or more (step
(3)). If the vehicle speed is not 30 km / h or higher, the vehicle is running at low speed and no alarm is issued. When the vehicle speed is 30 km / h or more, the inter-vehicle distance is displayed and the alarm is issued. Therefore, the laser light 16 having a large output is emitted from the light emitting unit 2 of the laser radar unit 1 (step (4)).

While the truck 12 is traveling, the inter-vehicle distance D is calculated in step (5) based on the above-described formula, the vehicle speed sensor 17 detects the vehicle speed Vf in step (6), and step (7) ), The front vehicle speed Va is obtained from the change in the inter-vehicle distance D and the own vehicle speed Vf as described above.

Next, the environment, that is, the road surface condition is detected by the environment sensor 24 or the like (step (8)). For example, it is detected whether the wiper switch 23 is in the ON state.

Next, the decelerations α ₁ and α _{2 of} the own vehicle and the front vehicle are changed according to the road surface condition (step (9)). If environmental information is not detected in the previous step (8), the default decelerations α ₁ and α ₂ are used as they are.

Next, at step (10), the safe inter-vehicle distance Ds is obtained from the vehicle speed Vf, the front vehicle speed Va, the decelerations α ₁ and α ₂ detected or calculated as described above. This safe inter-vehicle distance Ds is a value that is appropriately corrected in consideration of the speed of the front vehicle 22 and according to road surface conditions.

Next, the current inter-vehicle distance D is the safe inter-vehicle distance D.
It is judged whether it is within s (step (11)). If it is within the safe inter-vehicle distance Ds, the process proceeds to step (12), the alarm is not issued, and only the inter-vehicle distance is displayed on the display unit 21.

If it is determined in step (11) that the inter-vehicle distance D is smaller than the safe inter-vehicle distance Ds, then step (1)
In 3), the front vehicle speed Va and the own vehicle speed Vf are compared. When the front vehicle speed Va is high, the inter-vehicle distance D is in a state of increasing, and it is not necessary to issue an alarm, and the process proceeds to step (12).

When the front vehicle speed Va is smaller than the own vehicle speed Vf, it is in a region to be warned and is gradually approaching. Therefore, the process proceeds to step (14) to generate an alarm and display unit 2
The inter-vehicle distance is displayed in 1.

When the truck 12 is shipped, it is necessary to adjust the optical axis of the laser beam 16 emitted from the laser beam emitting section 2 of the laser radar unit 1. When this optical axis adjustment is performed, the switch 14a of the control unit 14 is turned on, and the optical axis adjustment mode is selected in step (2).

When the optical axis adjustment mode is selected, the laser light emitting section 2 of the laser radar unit 1 emits power-down laser light and the visible light emitting section 31.
Visible light 35 is emitted from the step ((15), (16)).
The optical axis of the laser light 16 is adjusted using the visible light 35 as a guide.

That is, as shown in FIG. 6B, the reflecting plate 41 is fixed at a predetermined position in front of the truck 12, and the visible light 35 is applied to the reflecting plate 41 so that the visible light 35 is at the predetermined position. The position of the laser radar unit 1 is adjusted so that it comes to. At the same time, since the laser light 16 is also emitted, the inter-vehicle distance is displayed based on the detection result of the reflector by the laser light 16 (step (17)), whereby the optical axis adjustment is confirmed. FIG. 6A shows a state in which the optical axis adjustment is accurate.

6A and 6B show the case where the laser radar unit 1 is arranged in the center of the vehicle, as shown in FIG. 6C, the laser radar unit 1
Can be applied even when is arranged with an offset S from the vehicle center. That is, since the position of the reflector 41 is known, the laser beam 16 is surely detected even in front of 100 m by adjusting the laser radar unit 1 based on the position of the visible light 35 hitting the reflector 41. The optical axis can be adjusted. It should be noted that FIG. 6D shows a state in which the optical axis adjustment is inaccurate.

[0040]

According to the optical axis adjusting device of the laser radar in the inter-vehicle distance detecting / warning device according to the present invention, the laser radar unit has a built-in visible light emitting section.
Since the optical axis of the laser light can be adjusted using visible light as a guide, the adjustment work becomes easy. Further, since the laser light is powered down during the adjustment, the laser light reflected by each part of the factory other than the reflection plate is sufficiently attenuated, and a highly accurate adjustment work can be realized only with necessary information.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an inter-vehicle distance detection / warning device that realizes an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a schematic mounting positional relationship of each component of the apparatus shown in FIG.

FIG. 3 is an explanatory diagram of a laser radar unit.

FIG. 4 is an explanatory diagram of an inter-vehicle distance, a braking distance, and the like.

FIG. 5 is a flowchart of an embodiment.

FIG. 6 is an explanatory diagram of optical axis adjustment.

[Explanation of symbols]

 1 Laser Radar Unit 2 Laser Light Emitting Section 3 Light Receiving Section 7 Vehicle Speed Sensor 12 Own Vehicle (Truck) 14 Control Unit 14a Switch 16 Laser Light 17 Vehicle Speed Sensor 21 Display Unit 22 Front Vehicle 31 Visible Light Emitting Section 35 Visible Light 41 Reflector

Claims (1)

[Claims] 1. When the vehicle speed detected by the vehicle speed sensor is equal to or higher than a predetermined value, the time until the laser light emitted from the laser radar unit of the own vehicle is reflected by the preceding vehicle and returned is detected to determine the inter-vehicle distance. The laser radar of the inter-vehicle distance detection / alarm device that has a control unit that issues an alarm when this inter-vehicle distance becomes smaller than the safe inter-vehicle distance determined based on the braking distance of the vehicle and the free running distance An optical axis adjusting device, wherein a visible light emitting portion is provided in a laser light emitting portion of the laser radar unit, and a switch means is turned on so that power is reduced from the laser light emitting portion even when the vehicle is stopped. The optical axis adjustment of the laser radar in the inter-vehicle distance detection / warning device is characterized in that visible light is emitted from the visible light emitting section as well as the laser light Apparatus.