JPH02151787A - Apparatus for recognizing environment of traveling car - Google Patents

Abstract

PURPOSE:To obtain efficient external information by a method wherein sampling interval of a sensor for sampling information on external environments with specified time intervals is variably controlled by a detector and a non-detector of obstruction. CONSTITUTION:A piezo-conversion element in a sensor unit 1 radiates ultrasonic waves when applied with driving pulse, and when it receives the echo, it outputs a voltage signal according to the echo intensity. It is rotated by a driving motor 6 and its direction of radiating ultrasonic waves can be changed by 360 degrees. A distance measuring apparatus 3 calculates a distance D to obstruction based on the echo signal 1 obtained by the unit 1 and an angle, etc. obtained by a sensor 2. This apparatus 3 verifies that the sensor 2 is not rotating and sends driving pulse to the unit 1 to have the unit 1 oscillate ultrasonic waves. An arthmatic unit 4 for increment widths calculates a swing angle alpha of an ultra sonic wave radiation direction from the unit 1 based on the distance D to the obstruction. A motor controller 5 calculates motor rotation time based on the angle alpha to have the motor rotated, informing the unit 3 that the unit 1 is not rotating.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention is directed to the environment of a mobile vehicle, which is used when a mobile vehicle equipped with an ultrasonic sensor that performs sector scanning, for example, runs while recognizing obstacles. Relating to a recognition device.

(Prior Art) Some mobile vehicles that recognize the outside world and perform autonomous driving control generally capture a front image using a camera or the like and perform environment recognition based on the image. The images captured by this camera have a wide recognition area and are characterized by the fact that it takes only a short time to acquire the image. On the other hand, there is also prior art, such as Japanese Patent Laid-Open No. 62-247407, which uses an ultrasonic sensor instead of a camera to obtain external world information.

In this prior art, a sector scan is performed by swinging an ultrasonic sensor at regular increments of angles, and information regarding obstacles is obtained from the echo signals.

(Problems to be Solved by the Invention) By the way, ultrasonic sensors generally have poor directivity and low resolution. Furthermore, since the speed of sound is relatively slow, a certain amount of time is required to receive the echo signal. Therefore, if sampling is performed at every fixed angle as in the prior art described above, obtaining external world information with high resolution and achieving efficient sampling will be contradictory. This is because, in order to obtain external world information with high resolution, the sampling interval must be made finer, but this increases the number of measurements per unit time, which inevitably lengthens the processing time. However, if the obstacle did not exist, the long measurement time and processing time would be wasted.

The contradiction between obtaining high-resolution external world information and achieving efficient sampling is not only a problem when measuring external world information using ultrasonic sensors, but also when measuring real-time information such as camera images. It can also happen when you get .

This is because even with camera images, acquiring an image through sampling and recognizing an obstacle from that image are two different things, and if there are no obstacles in the image, the recognition operation is wasted. Because it will return.

SUMMARY OF THE INVENTION The present invention was proposed in order to eliminate the drawbacks of the above-mentioned conventional examples, and its purpose is to propose an environment recognition device for a moving vehicle that can efficiently acquire external world information.

(Means and operations for achieving the object) In order to achieve the above object, the configuration of the environment recognition device for a moving vehicle according to the present invention performs a predetermined movement and samples information of the external environment at predetermined time intervals. An environment recognition device for a moving vehicle equipped with a sensor, characterized by comprising a control means for variably controlling the sampling interval of the sensor depending on whether an obstacle is detected or not.

(Embodiment) An embodiment in which the present invention is applied to obstacle recognition in travel control of a moving vehicle will be described below with reference to the accompanying drawings.

FIG. 1 is an overall diagram of a recognition device according to this embodiment. This recognition device is installed in a vehicle (for example, an unmanned vehicle or an automobile) not shown. In the figure, 1 is an ultrasonic sensor unit, and 2 is a sensor for detecting the direction in which the sensor unit 1 emits ultrasonic waves. The details are shown in FIGS. 2, 3A, and 3B. As will be described later, a piezo conversion element is provided within this sensor unit, and this conversion element emits an ultrasonic wave (approximately 40 KHz in this example) when a driving pulse is applied, and its echo is When received, it outputs a voltage signal according to the echo intensity. Further, this sensor unit 1 is rotated by a drive motor 6 and can change the ultrasonic emission direction within a range of 360 degrees. Reference numeral 3 denotes a distance measuring device for calculating the distance to an obstacle based on the echo signal obtained by the unit 1 and the angle obtained by the sensor 2. The distance measuring device 3 confirms that the sensor 1 is not rotating, and sends a drive pulse to the sensor unit 1, causing the unit 1 to oscillate ultrasonic waves.

The step size calculation device 4 calculates the swing angle α in the direction of ultrasonic radiation from the sensor unit 1 based on the distance to the obstacle. A motor 6 for driving the sensor unit 1 is rotated by a signal from the motor control section 5. The motor control unit 5 calculates a motor rotation time T from the step width α, and rotates the motor 6 at a constant angular velocity ω during the period T. Further, the motor control unit 5 notifies the distance measuring device 3 that the sensor unit 1 is not rotating. This is because the distance measuring device 3 knows the timing at which the sensor unit 1 can emit ultrasonic waves.

FIGS. 2 and 3 show two examples of the overall configuration of the ultrasonic sensor unit l. The configuration of the sensor unit 1 shown in FIG. 2 will be explained. In this unit, piezo element 10
a itself is fixed, but the reflecting mirror 12a is rotated by the motor 6 to change the ultrasonic emission direction to any direction within 360 degrees. It is located in The shape of the radiation cross section of the piezo element 10a is approximately circular. The reflecting mirror 12a is the element 1
The ultrasonic wave from 0a is incident at an incident angle of 45 degrees, and the reflection angle is 45 degrees.
It is fixed to the rotating shaft body 13 so as to be reflected at a certain angle. Note that lla is a support for supporting the piezo element 10a at a predetermined position on the sensor unit base 14a. The cross-sectional shape of the reflecting mirror 12a is approximately elliptical.

By the way, in the sensor unit having the structure shown in FIG. 2, when the reflecting mirror 12a rotates, the ultrasonic emission direction may coincide with the column of the support 11a, and in that case, noise is mixed into the echo signal. In order to avoid this inconvenience, the sensor unit shown in FIG. 3 has been proposed. In FIG. 3, the piezo element 10b itself is fixed, but the reflecting mirror 12
In some cases, the piezo element 10b is rotated by the motor 6 to change the ultrasonic emission direction, but the piezo element 10b is placed downward, and the reflecting mirror 12 is rotated by the motor 6.
a is located above. Further, the reflecting mirror 12b is fixed to the link gear 21 by a support body 11b. The link gear 21 is a cylindrical gear rotatably supported around the circular piezo element 10b, and meshes with the gear 20 rotated by the drive motor 6. Since the pillar 11b is always located on the opposite side to the ultrasonic radiation direction, the pillar 11b
The echo from b will not be mixed into the echo signal.

Both the ultrasonic sensor unit in the form shown in Fig. 2 and the ultrasonic sensor unit in the form shown in Fig. 3 can be installed in the system shown in Fig. 1 without changing any other elements, so in the following explanation, No particular distinction is made between sensor units.

FIG. 4A is a diagram showing the directivity of ultrasonic waves emitted from the sensor unit 1. As is well known, ultrasonic waves are emitted from the piezo element with a certain spread width. Although this expansion width changes depending on the ultrasonic frequency, the shape of the piezo element, etc., once these factors are determined, it does not change and is unique to the sensor unit. FIG. 4B is a diagram illustrating a method of measuring the distance to an obstacle using the distance measuring device 3. According to the figure, the distance is determined by the time t from oscillating the drive pulse to receiving the echo. From, it is obtained by . Here, C is the speed of sound in air.

FIG. 5 is a diagram showing the operating principle of this embodiment, and shows how the step size α of the ultrasonic radiation angle determined by the step size calculating device 4 changes depending on the presence or absence of an obstacle. .

In FIG. 5A, the sensor unit l rotates clockwise and its radial range is I -> II ->
It changes from IV to V in m. Also, 1
00 is an obstacle.

This control of the step width α changes the next radial direction by an angle compared to the previous direction if no obstacle is detected in the previous sampling. Here, b is the spread angle of the ultrasonic beam in FIG. 4A. The step angle is used because if there is an obstacle within the range of the angle, at least a pulse component will appear in the echo signal, so at least the presence of the obstacle can always be detected. On the other hand, if an obstacle is detected in the previous sampling, the next radiation direction is swung by an angle greater than the current direction. here,
DR is the required resolution and is a constant. That is, once the presence of an obstacle is detected even at -degrees, echo signals for recognizing the obstacle can be obtained with DR resolution until the presence of the obstacle can no longer be detected.

The principle of operation will be explained according to FIGS. 5A and 5B. When the radiation direction is I, since there is no pulse component having an amplitude above a certain level in the echo signal, it is determined that there is no obstacle. Then, the next radial direction II is a position shifted by b from the current position.

If the rotational angular velocity of the drive motor 6 is ω (=constant), then α=b=ω·Tt. That is, the motor control unit 5 maintains the angular velocity ω during the period Tt.
Therefore, in the zero-order radiation direction II in which the motor 6 is rotated, a pulse component indicating the presence of an obstacle appears in the echo signal, so that the presence of the obstacle is recognized. Therefore, if the next step angle α is as follows, and the driving period of the motor 6 at this time is T2, then α=ω・T.

It is. The presence of the obstacle 100 continues to be detected until the radiation position ■. When no obstacle is detected at the radial position ■, the increment angle a returns to b. According to the above formula, the increment angle α becomes smaller as the distance to the obstacle increases. this is,
This is because as D becomes larger, the spread width of the ultrasonic beam at that position becomes larger, and unless α is reduced accordingly, the required resolution cannot be guaranteed.

FIG. 6 is a flowchart of a control procedure related to the step angle control shown in FIG. Note that recognition of the presence or absence of an obstacle is performed in step SL2.

In this way, according to the above embodiment, until an obstacle is detected, the emission direction of the ultrasonic wave is simply changed at every increment angle α (=b) that is rough enough to detect the presence of the obstacle. ,
The number of sampling times per unit time of ultrasonic oscillation and echo reception for recognizing the presence of an obstacle, and the number of times of data processing for detecting the presence of an obstacle are reduced. Therefore, if this control is performed by a microprocessor, etc.,
The load on the microprocessor is reduced. Also, -dan,
Once the presence of an obstacle is recognized, the increments angle will be such as to ensure that information of sufficient resolution is obtained to recognize the shape and position of the obstacle, so the power of the microprocessor can be used to determine the shape and position of the object. As much as possible can be devoted to position recognition processing. Therefore, the efficiency of obstacle recognition can be improved as a whole.

In the embodiments described above, recognition accuracy of the zero position of the object shape is ensured by controlling the increment angle according to the distance from the sensor position to the obstacle. However, for example, if the shape of the object changes rapidly in the ultrasonic emission direction, it becomes difficult to ensure accuracy.

Therefore, a modified example method of step angle control based on the principle shown in FIG. 7 is proposed. Moreover, FIG. 8 is a flowchart relating to control of this modification. In FIG. 7A, D, l-z, Dn-t, Dn.

D, 1.1 magnification is the ultrasonic radiation range x, xr, Xll
, XI(7) is the distance to the obstacle obtained for each sampling. Obstacles continue to be detected in the radiation ranges X, XI, and XII, so the radiation ranges X,
The step angle α for XI, XI[ is determined by: However, due to the shape of the obstacle 100, the distance D7 obtained in the sampling of the radiation range (3) suddenly changes from the distance Dn-1 obtained in the previous sampling. In the example of FIG. 7, Dn-I)n-+)1. In the control procedure shown in FIG. 8, detection of this sudden change in distance measurement is determined in step S36 according to Dn-Dn-1>a. Here, a is a positive constant value. When there is a large change in distance, such as when the radiation range x+=>double, the increment angle for the radiation range layer, that is, the deflection angle α from radiation range ■ to radiation range ■, is a= Determined from Min(b, ao, (!+). Here, α. is as described above, and α1 is determined from the method shown in FIG. 7B. That is, DR, D-, D-+ The angle α1 of the side DR of the triangle with three sides is as follows.In Figure 7B, DR is a constant value, so
The larger D, l is than D n-1, the angle α
, becomes smaller. Fig. 7B shows the case where D, -D, ,>1, but the same is true when Dn is smaller than Dn-1, so in general, the larger ID1l-Dl, -I+, the more α1 becomes smaller.

Therefore, α = ! Ain(b, αG, α
), sampling will be performed with the finest precision. In this way, resolution can be ensured even if the shape of the obstacle changes rapidly with respect to the ultrasound irradiation direction.

One embodiment and its variations have been described above. In these examples, an example of an ultrasonic sensor is used as an information input source for object recognition, but the present invention can be applied to any sensor that can at least confirm the presence of an obstacle, such as a radar sensor. is applicable.

Further, in the above two examples, the sensors for obtaining information for obstacle detection and environment recognition are the same, but these may be different sensors. In this case, the presence of obstacles is not required to be detected with high precision, so it is performed using, for example, an ultrasonic sensor or an infrared sensor, and environment recognition is performed using a rotary camera, etc.
The frequency of image capture by this camera is kept low until the presence of an obstacle is detected.

In addition, in the above two examples, the sensor that obtains information for environmental recognition rotates 360 degrees in all directions, but it scans only a part of an arc-shaped area (for example, a certain range in front). The present invention is applicable even in such cases.

Further, the direction of rotation or rotation of the sensor l is not limited to being carried out in a horizontal plane, but may be carried out, for example, in a vertical plane.

(Effects of the Invention) As explained above, the configuration of the environment recognition device for a moving vehicle according to the present invention is the environment of a moving vehicle equipped with a sensor that performs a predetermined movement and samples information of the external environment at predetermined time intervals. The recognition device is characterized in that it includes a control means that variably controls the sampling interval of the sensor depending on when an obstacle is detected and when it is not detected.

Therefore, when no obstacles are detected, for example, the sampling interval is lengthened to roughly collect external environment information to reduce the burden.
When detecting obstacles, the sampling interval is shortened to collect detailed information, increasing the accuracy of environmental recognition, and overall improving the efficiency of environmental recognition.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the overall configuration of one embodiment of an environment recognition device to which the present invention is applied, Fig. 2 is a diagram showing an example of the configuration of an ultrasonic sensor unit, and Figs. 3A and 3B are ultrasonic sensor units. 4A is a diagram illustrating the directivity of the ultrasonic sensor used in the example; FIG. 4B is a diagram illustrating the principle of distance measurement; Fig. 5B is a diagram explaining the principle of one embodiment of the increment angle control, Fig. 6 is a flow chart showing the procedure of the increment angle control shown in Fig. 5A, and Figs. 7A and 7B are modified examples of the increment angle control. FIG. 8 is a flowchart showing the steps of the step angle control shown in FIG. 6A. In the figure, l...Ultrasonic sensor unit, 2...Position angle sensor, 3...Distance measuring device, 4...Step size calculation device, 5...
... Motor control unit, 6... Drive motor, 10a, 10
b... Piezo element, lla, 11b... Support, 1
2a. 12 b... Reflector, 14a, 14b-... Sensor base, 20.21... Link gear, 100-... Obstacle, D... Distance to obstacle, Dll... Resolution Distance, ■−■... Ultrasonic emission area. Figure 3B Figure 2 Figure 4A Figure 6

Claims (1)

[Claims] (1) An environment recognition device for a mobile vehicle equipped with a sensor that performs a predetermined movement and samples information about the external environment at predetermined time intervals, and the sampling interval of the sensor is set to be different from when an obstacle is detected. An environment recognition device for a moving vehicle, characterized by comprising a control means that performs variable control depending on the time of detection.