JP2017173150A - Obstacle detection unit, method, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correctly specify a position of an obstacle even when sweep is performed such that the obstacle is searched using a high directivity ultrasonic generator having a large side lobe regarding a technique for detecting the obstacle using an ultrasonic generator/detector.SOLUTION: A microcomputer 101 determines change in an echo image by an ultrasonic detection signal S2 detected via an ultrasonic microphone 104 and a receiving amplifier 105 while an amplification degree of the receiving amplifier 105 is gradually changed from a low state to a high state by an amplification degree control signal S5. The microcomputer 101 determines whether a virtual image corresponding to the detected echo image is detected or not after the echo image is firstly detected to detect an obstacle based on the echo image just before determination when the virtual image is determined to be detected.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an obstacle detection apparatus, method, and program for detecting an obstacle using an ultrasonic generator / detector.

  Household robots have begun to spread as cleaning robots and partner robots that support people's lives. These home robots need to detect obstacles in order to move around the room, and are equipped with various sensors. Among them, an ultrasonic distance sensor is often used because it can detect an accurate distance at a low cost. However, the conventional ultrasonic distance sensor has low directivity of the ultrasonic beam, and roughly measures whether or not there is a wall in the four directions of front and rear, left and right, and measures the distance from the wall. The location of the obstacle could not be determined.

  In order to be able to use the ultrasonic distance sensor to locate obstacles, it is considered that the directivity of the ultrasonic beam should be high. Conventionally, a technology for generating an ultrasonic beam with high directivity has been practically used. It has become. As a typical conventional technique, a technique for increasing the straightness of ultrasonic waves by obtaining a spatial parametric effect by arranging a large number of small ultrasonic generators on a plane is generally widely known as a parametric ultrasonic speaker. (For example, the technique described in Patent Document 1).

  As a second conventional technique, a technique using a piston-shaped ultrasonic generator and a technique for generating directivity by generating sound waves of two frequencies and generating a difference between them are proposed. (For example, the technique described in Patent Document 2).

JP 2005-049303 A JP 2005-351897 A

  In the techniques as exemplified in Patent Documents 1 and 2, it is considered that the position of an obstacle can be specified by emitting an ultrasonic beam in multiple directions using a highly directional ultrasonic generator and detecting the echo. In practice, however, the low-cost and easy-to-make parametric speaker has the disadvantage that side lobes are likely to occur, and other high-directivity ultrasonic generators cannot eliminate side lobes at all. If there is, there is a problem that the ultrasonic waves of the side lobes are reflected and detected as echoes, and the position of the obstacle cannot be specified.

  Accordingly, an object of the present invention is to enable the position of an obstacle to be accurately identified even when a sweep for searching for an obstacle is performed using a highly directional ultrasonic generator having a large side lobe.

  In an example of the embodiment, the obstacle detection apparatus includes an ultrasonic generator having a directivity, an ultrasonic detector, and a control unit, and detects an obstacle, and the control unit is configured to transmit the ultrasonic signal with a transmission intensity or an ultrasonic wave. An obstacle is detected by controlling the reception sensitivity of the sound wave detector and determining the change in the echo image detected through the ultrasonic wave detector while controlling the transmission intensity or the reception sensitivity.

  According to the present invention, it is possible to accurately identify the position of an obstacle even when searching for an obstacle using a highly directional ultrasonic generator having a large side lobe.

It is a block diagram which shows the structural example of embodiment of an obstruction detection apparatus. 3 is a plan view showing a configuration example of an ultrasonic speaker array 103. FIG. It is a figure which shows the structural example of an open type ultrasonic transducer. It is a figure which shows the example of the directivity chart of an open type ultrasonic transducer and an ultrasonic speaker array. It is a timing chart which shows the example of a waveform of a control signal of an obstacle detection device. It is a figure which shows the example of the echo image when not performing amplification degree control of a receiving amplifier. It is a block diagram which shows the hardware structural example of a microcomputer. It is a flowchart which shows the example of an obstruction detection process. It is a figure which shows the example of the echo image by this embodiment. It is a figure which shows the structural example and arrangement example of the robot carrying the obstacle detection apparatus by this embodiment.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram illustrating a configuration example of an embodiment of an obstacle detection device. The microcomputer 101 generates a pulse burst signal S1. The drive amplifier 102 amplifies the pulse burst signal S 1 output from the microcomputer 101 and supplies a drive voltage signal to the ultrasonic speaker array 103. The ultrasonic speaker array 103 is swept by a sweep drive unit 108 controlled by the microcomputer 101. The ultrasonic waves generated by the ultrasonic speaker array 103 are transmitted through the space, reflected particularly by an obstacle (not shown), and returned to the ultrasonic microphone 104. The reception amplifier 105 amplifies the output of the ultrasonic microphone 104 and outputs an ultrasonic detection signal S2. The envelope generator 106 generates an envelope of the ultrasonic detection signal S2 and outputs an envelope signal S3. The comparator 107 performs a threshold determination on the envelope signal S3, thereby outputting a rectangular wave signal S4 and causing the microcomputer 101 to input the rectangular wave signal S4. The microcomputer 101 outputs the amplification degree control signal S5 and inputs it to the reception amplifier 105. The amplification degree of the reception amplifier 105 is controlled by this amplification degree control signal S5. The amplification degree of the reception amplifier 105 can be easily realized by switching the resistance constant of the operational amplifier with an analog switch, for example, but may be realized by any other method.

  FIG. 2 is a plan view showing a configuration example of the ultrasonic speaker array 103 of FIG. The ultrasonic speaker array 103 has a configuration in which twelve open ultrasonic transducers 201 are arranged on a printed wiring board 202, for example, in 3 rows × 4 columns. An ultrasonic microphone 104 constituted by one open ultrasonic transducer 201 is disposed under the printed wiring board 202. A connector 203 connected to the printed wiring board 202 connects each open type ultrasonic transducer 201 constituting the ultrasonic speaker array 103 to the drive amplifier 102 of FIG. 201 is connected to the receiving amplifier 105 of FIG.

  3A and 3B are diagrams showing one configuration example of the open-type ultrasonic transducer 201 in FIG. 2, FIG. 2A is a side perspective view, FIG. 2B is a perspective view of the transducer body, and FIG. c) is a perspective view of the case 308 and the screen 309. A transducer body in which a square bimorph vibrator 303, a metal plate 302 as a vibration plate, and a cone-shaped resonator 301 are stacked in order from the bottom is bonded to an upper portion of a fulcrum (base) 306 with an adhesive 307. An electrode terminal 304 is connected to the bimorph vibrator 303 via a lead wire 305. The transducer body portion is protected by a case 308 having a screen 309 at the top. The two electrode terminals 304 are connected to the drive amplifier 102 of FIG. 1 via the connector 203 of FIG.

  4A shows an example of one directivity chart of the open-type ultrasonic transducer 201, and FIG. 4B shows an example of the directivity chart of the ultrasonic speaker array 103. FIG. The directivity chart 401 having only one open ultrasonic transducer 201 has directivity as shown in FIG. 4A, but is not sharp directivity. Therefore, only one transducer is not suitable for accurately detecting an obstacle. On the other hand, the directivity chart 402 of the ultrasonic speaker array 103 composed of a plurality of open-type ultrasonic transducers 201 has a sharp main lobe as shown in FIG. I understand that.

  FIG. 5 is a timing chart showing examples of waveforms of control signals S1, S2, S3, and S4 of the obstacle detection apparatus 100 of FIG. The microcomputer 101 in FIG. 1 determines the time until the rectangular wave signal S4 illustrated in FIG. 5A returns from the start time of the pulse burst signal S1 illustrated in FIG. The distance traveled by the ultrasonic wave can be calculated by measuring and multiplying the time by the speed of sound. The distance to the obstacle is half that length.

  FIG. 6 is a diagram illustrating an example of an echo image when the microcomputer 101 does not perform the amplification degree control of the reception amplifier 105 in FIG. In FIG. 1, when ultrasonic echoes are repeatedly measured while sweeping the entire ultrasonic speaker array 103 by the sweep drive unit 108, the position of the obstacle can be plotted on the polar coordinates as shown in FIG. FIG. 6A is a diagram showing a result of scanning with a metal cylinder having a diameter of about 6 cm placed at a distance of about 1 m from the obstacle detection apparatus 100 of FIG. The ultrasonic speaker array 103 is arranged at the center of the sector shape in FIG. 6A, and the inner sector shape represents a distance of 1 m, and the outer sector shape represents a distance of 2 m. A black dot is a plot of the measurement result, and a dot arranged outside the outermost fan-shaped figure is a result plotted at the maximum calculated value when the echo does not come back. In FIG. 6A, an echo image of the ultrasonic wave reflected on the cylinder appears at the center at a distance of about 1 m. FIG. 6B is a plot when the cylinder is scanned at a distance of about 0.5 m. The image reflected by the cylinder is plotted at the correct position, but similar images appear on the left and right of the image, and it looks as if multiple cylinders are lined up. This is a virtual image with respect to the echo image that appears because the ultrasonic side lobe emitted from the ultrasonic speaker array 103 having the characteristics of the directivity chart 402 illustrated in FIG. 4B is reflected. However, the observer cannot know from this image alone whether a virtual image is visible or whether an echo image due to an obstacle is actually visible like this image. In the case of a metal cylinder with a diameter of 6 cm, an echo image without a virtual image is plotted at a distance of 1 m, and a virtual image appears at a distance of 0.5 m, but the ultrasonic reflection intensity varies greatly depending on the shape and material of the obstacle. It is impossible to know in advance which distance the virtual image will appear.

  In particular, when an inexpensive open-type ultrasonic transducer 201 is used for cost reduction, the side lobe on the directivity chart 402 illustrated in FIG. 4B is large. Accordingly, in FIG. 1, when the amplification factor of the reception amplifier 105 and the drive voltage of the drive amplifier 102 are constant, the detection is performed by the ultrasonic microphone 104 and is amplified by the reception amplifier 105. In some cases, the waveform of the ultrasonic detection signal S2 is greatly disturbed by the virtual image of the echo image. In this case, the envelope signal S3 shown in FIG. 5B also does not have a correct waveform corresponding to the distance of the obstacle, and the change timing of the rectangular wave signal S4 shown in FIG. The computer 101 cannot correctly detect the direction and distance of the obstacle.

  Therefore, in this embodiment, in FIG. 1, the microcomputer 101 gradually changes the amplification degree of the reception amplifier 105 from the low state to the high state by the amplification degree control signal S5, so that the reception sensitivity is changed from the low state to the high state. It is possible to correctly detect an obstacle by determining a change in the echo image due to the ultrasonic detection signal S2 while gradually changing to.

  FIG. 7 is a diagram showing an example of a hardware configuration of the microcomputer 101 in FIG. 1 that can realize this control operation as software processing. The microcomputer 101 having the configuration shown in FIG. 7 includes a CPU 701, a memory 702, an input device 703, an output device 704, an external storage device 705, a portable recording medium driving device 706 into which a portable recording medium 709 is inserted, and communication. An interface 707 is included, and these are connected to each other by a bus 708. The configuration shown in the figure is an example of a hardware configuration capable of realizing the microcomputer 101, and the microcomputer 101 is not limited to this hardware configuration.

  The CPU 701 controls the entire computer. The memory 702 stores programs or data stored in the external storage device 705 (or portable recording medium 709) when executing an obstacle detection processing program exemplified in the flowchart of FIG. It is a memory such as a RAM for temporarily storing. The CUP 701 performs overall control by reading the program into the memory 702 and executing it.

  The input device 703 detects an input operation by a user using a keyboard, a mouse, or the like, and notifies the CPU 701 of the detection result. The output device 704 outputs data sent under the control of the CPU 701 to a display device or a printing device.

  The external storage device 705 is, for example, a hard disk storage device. Mainly used for storing various data and programs.

  The portable recording medium driving device 706 accommodates a portable recording medium 709 such as an SDRAM or a compact flash, and has an auxiliary role for the external storage device 705.

  The communication interface 707 is a device for connecting, for example, a LAN (local area network) or WAN (wide area network) communication line.

  FIG. 8 is a flowchart illustrating an example of the obstacle detection process. This processing is realized by the CPU 701 in FIG. 7 executing the obstacle detection processing program stored in the memory 702. The program may be distributed by being recorded in, for example, the external storage device 705 or the portable recording medium 709, or may be acquired from the network by the communication interface 707.

  In FIG. 8, the CPU 701 first sets the amplification level to the minimum level in the amplification degree control signal S5 supplied to the reception amplifier 105 in FIG. 1 (step S801).

  Next, the CPU 701 generates the pulse burst signal S1 of FIG. 1 while driving the sweep drive unit 108 of FIG. 1 to perform the sweep operation, and supplies it to the drive amplifier 102 (step S802).

  Subsequently, the CPU 701 determines whether an echo image is obtained from the comparator 107 in FIG. 1 (step S803).

  If the determination in step S803 is NO, the CPU 701 increases the amplification in the amplification control signal S5 supplied to the reception amplifier 105 in FIG. 1 (step S804).

  At this time, the CPU 701 determines whether or not the amplification degree increased in step S804 exceeds the maximum gain of the reception amplifier 105 (step S805).

  If the determination in step S805 is NO, the CPU 701 returns to the process in step S802, and tries to detect and detect the echo image again under the new amplification level in the reception amplifier 105.

  As a result of the iterative processing from step S802 to S805, if an echo image is detected and the determination in step S803 is YES, the CPU 701, if present, is detected up to the previous time and is stored in, for example, the memory 702 in FIG. The echo image being detected is compared with the echo image detected this time (step S806).

  As a result of the comparison in step S806, the CPU 701 determines whether or not a virtual image has been detected around the previous echo image (step S807).

  If the determination in step S807 is NO, the CPU 701 proceeds to the process in step S804 and further increases the amplification factor for the reception amplifier 105.

  If the determination in step S807 is YES due to the detection of the virtual image, the CPU 701 adopts the previous echo image stored in the memory 702 as a correct echo image and detects the direction and distance of the existing obstacle. Is executed (step S808). Thereafter, the CPU 701 ends the obstacle detection process shown in the flowchart of FIG.

  FIG. 9 is a diagram illustrating an example of an echo image detected by the obstacle detection process illustrated in the flowchart of FIG. FIG. 9A is a plot when the obstacle is not visible because the amplification degree of the reception amplifier 105 is small. When the amplification degree of the receiving amplifier 105 is increased stepwise, the reflected echo from the nearest obstacle is detected as shown in FIG. 9B. FIG. 9C is a plot diagram when a virtual image appears as a result of further increasing the amplification factor of the reception amplifier 105. The CPU 701 in FIG. 7 compares the previous echo image held in the memory 702 with the current echo image, and determines that this is a virtual image if an echo image appears at the same distance around the previous echo image. it can. Therefore, when a virtual image appears, the CPU 701 can specify the position of the obstacle at the closest distance using the previous echo image.

  In the embodiment described above, the algorithm illustrated in the flowchart of FIG. 8 has been described as being processed by the CPU 701 of FIG. 7 constituting the microcomputer 101 of FIG. The processing device may be configured to process the algorithm exemplified in the flowchart of FIG.

  In the present embodiment, the microcomputer 101 is configured to control the amplification degree of the reception amplifier 105, but the transmission intensity of the ultrasonic speaker array 103 that is an ultrasonic generator or the reception of the ultrasonic microphone 104 that is an ultrasonic detector. What is the configuration as long as the configuration detects the obstacle by determining the change in the echo image detected through the ultrasonic microphone 104 while controlling the sensitivity and controlling the transmission intensity or the reception sensitivity? It may be. For example, in FIG. 1, the microcomputer 101 may be configured to gradually change the drive voltage of the drive amplifier 102 from a low state to a high state, not the amplification degree of the reception amplifier 105. Alternatively, the microcomputer 101 is configured to gradually change the transmission intensity in the ultrasonic speaker array 103 from a low state to a high state by gradually changing the number of burst pulses in the pulse burst signal S1 from a small state to a large state. There may be.

  FIG. 10A is a diagram illustrating a configuration example of a robot 1001 equipped with the obstacle detection device according to the present embodiment. In the opening 1003 in the front part of the housing 1002 of the robot 1001, the printed wiring board 202 in FIG. 2 provided with the ultrasonic speaker array 103 and the ultrasonic microphone 104 in FIG. Is installed in a state where it can be swept. The control box 1004 incorporates the microcomputer 101, the drive amplifier 102, the reception amplifier 105, the envelope generator 106, and the connector 203 shown in FIG. The drive amplifier 102 in the control box 1004 is connected to the printed wiring board 202 via the connector 203 in FIG. The microcomputer 101 in the control box 1004 is connected to the sweep drive unit 108.

  When the robot 1001 having the configuration example of FIG. 10A moves in a room 1005 as shown in FIG. 10B, for example, the ultrasonic speaker array is used by the sweep drive unit 108 of FIG. The robot 1001 moves while detecting obstacles 1006a and 1006b in the room 1005 by sweep driving the printed wiring board 202 on which the 103 and the ultrasonic microphone 104 are arranged.

Regarding the above embodiment, the following additional notes are disclosed.
(Appendix 1)
An obstacle detection device that detects an obstacle with a directivity ultrasonic generator, an ultrasonic detector, and a control unit, the control unit,
Control the transmission intensity of the ultrasonic generator or the reception sensitivity of the ultrasonic detector,
An obstacle detection device that detects the obstacle by determining a change in an echo image detected through the ultrasonic detector while performing control to change the transmission intensity or the reception sensitivity.
(Appendix 2)
Whether the virtual image corresponding to the detected echo image has been detected after the echo image is first detected while the control unit gradually changes the transmission intensity or the reception sensitivity from a low state to a high state. The obstacle detection device according to appendix 1, wherein when the virtual image is detected, the obstacle is detected based on the echo image immediately before the determination.
(Appendix 3)
The ultrasonic detector includes a variable amplification receiving amplifier that amplifies the output of the ultrasonic detection signal,
The obstacle detection device according to attachment 2, wherein the control unit gradually changes the reception sensitivity from a low state to a high state by gradually changing the amplification degree of the reception amplifier from a low state to a high state.
(Appendix 4)
The ultrasonic generator includes a drive amplifier for generating ultrasonic waves,
The obstacle detection device according to appendix 2, wherein the control unit gradually changes the transmission intensity from a low state to a high state by gradually changing the drive voltage of the drive amplifier from a low state to a high state.
(Appendix 5)
The ultrasonic generator includes a burst generation circuit for generating ultrasonic waves in bursts,
The obstacle detection device according to appendix 2, wherein the control unit gradually changes the transmission intensity from a low state to a high state by gradually changing the number of burst pulses in the burst generation circuit from a small state to a large state.
(Appendix 6)
The ultrasonic generator includes an ultrasonic speaker array configured by arranging open-type ultrasonic transducers in an array, and the ultrasonic detector includes an ultrasonic microphone based on the open-type ultrasonic transducer. 5. The obstacle detection device according to any one of 5.
(Appendix 7)
The obstacle detection device according to any one of appendices 1 to 6, further comprising a sweep drive unit that sweeps the ultrasonic generator.
(Appendix 8)
An obstacle detection method for detecting an obstacle by controlling a directivity ultrasonic generator, an ultrasonic detector, and a control unit,
Control the transmission intensity of the ultrasonic generator or the reception sensitivity of the ultrasonic detector;
An obstacle detection method for detecting the obstacle by determining a change in an echo image detected through the ultrasonic detector while performing control to change the transmission intensity or the reception sensitivity.
(Appendix 9)
To a computer that detects obstacles by controlling a directivity ultrasonic generator, ultrasonic detector, and control unit,
Controlling the transmission intensity of the ultrasonic generator or the reception sensitivity of the ultrasonic detector;
Detecting the obstacle by determining a change in an echo image detected through the ultrasonic detector while performing control to change the transmission intensity or the reception sensitivity; and
A program for running

DESCRIPTION OF SYMBOLS 100 Obstacle detection apparatus 101 Microcomputer 102 Drive amplifier 103 Ultrasonic speaker array 104 Ultrasonic microphone 105 Reception amplifier 106 Envelope generator 107 Comparator 108 Sweep drive part 201 Open type ultrasonic transducer 202 Printed wiring board 203 Connector 301 Cone-shaped resonance Child 302 Metal plate (diaphragm)
303 Bimorph vibrator 304 Electrode terminal 305 Lead wire 306 Support point (base)
307 Adhesive 308 Case 309 Screen 1001 Robot 1002 Housing 1003 Opening 1004 Control box

Claims (9)

An obstacle detection device that detects an obstacle with a directivity ultrasonic generator, an ultrasonic detector, and a control unit, the control unit,
Control the transmission intensity of the ultrasonic generator or the reception sensitivity of the ultrasonic detector,
An obstacle detection device that detects the obstacle by determining a change in an echo image detected through the ultrasonic detector while performing control to change the transmission intensity or the reception sensitivity.   Whether the virtual image corresponding to the detected echo image has been detected after the echo image is first detected while the control unit gradually changes the transmission intensity or the reception sensitivity from a low state to a high state. The obstacle detection device according to claim 1, wherein when the virtual image is detected and the virtual image is detected, the obstacle is detected based on the echo image immediately before the determination. The ultrasonic detector includes a variable amplification receiving amplifier that amplifies the output of the ultrasonic detection signal,
The obstacle detection device according to claim 2, wherein the control unit gradually changes the reception sensitivity from a low state to a high state by gradually changing the amplification degree of the reception amplifier from a low state to a high state. The ultrasonic generator includes a drive amplifier for generating ultrasonic waves,
The obstacle detection device according to claim 2, wherein the control unit gradually changes the transmission intensity from a low state to a high state by gradually changing the drive voltage of the drive amplifier from a low state to a high state. The ultrasonic generator includes a burst generation circuit for generating ultrasonic waves in bursts,
The obstacle detection device according to claim 2, wherein the control unit gradually changes the transmission intensity from a low state to a high state by gradually changing the number of burst pulses in the burst generation circuit from a low state to a high state. .   The ultrasonic generator includes an ultrasonic speaker array configured by arranging open ultrasonic transducers in an array, and the ultrasonic detector includes an ultrasonic microphone based on the open ultrasonic transducer. The obstacle detection device according to any one of 5 to 5.   The obstacle detection device according to claim 1, further comprising a sweep drive unit that sweeps the ultrasonic generator. An obstacle detection method for detecting an obstacle by controlling a directivity ultrasonic generator, an ultrasonic detector, and a control unit,
Control the transmission intensity of the ultrasonic generator or the reception sensitivity of the ultrasonic detector;
An obstacle detection method for detecting the obstacle by determining a change in an echo image detected through the ultrasonic detector while performing control to change the transmission intensity or the reception sensitivity. To a computer that detects obstacles by controlling a directivity ultrasonic generator, ultrasonic detector, and control unit,
Controlling the transmission intensity of the ultrasonic generator or the reception sensitivity of the ultrasonic detector;
Detecting the obstacle by determining a change in an echo image detected through the ultrasonic detector while performing control to change the transmission intensity or the reception sensitivity; and
A program for running