JPH06174829A - Ultrasonic sensor and moving work robot therewith - Google Patents

Abstract

PURPOSE:To provide a wide angle ultrasonic sensor capable of detecting a short range object, in which direct waves from a transmission oscillating element to a receiving oscillating element are reduced. CONSTITUTION:The sensor is provided with ultrasonic oscillating elements 41, 42 for transmission or receiving and a buffle plate 45 having a pair of openings 46, 47 for juxtaposing the oscillating elements 41, 42. Edges 46', 47' acute to a front face of the buffle plate 45 are formed at peripheries of the openings 46, 47, and three or more protrusions 52, 53 which are not obstructing opening areas and whose ends are positioned at the same distances from the front face are provided at rear faces of the edges 46', 47'. The ultrasonic oscillating elements 41, 42 for transmission or receiving are arranged rearward of the edges 46', 47' at the peripheries of the openings 46, 47, being in contact with the protrusions 52, 53 of the buffle plate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic sensor used for an obstacle detection device or a distance measuring device of a mobile work robot such as an automatic floor cleaner or an automated guided vehicle, and a mobile work robot having the ultrasonic sensor. .

[0002]

2. Description of the Related Art Conventionally, a means for measuring the presence or absence of an object or the distance to an object by transmitting an ultrasonic wave from an ultrasonic vibration element and receiving the reflected wave is an object detection sensor or a distance measuring sensor. It is used in various devices. As a distance-measuring sensor, it is usual to provide a horn by providing a horn on the front surface of the ultrasonic vibration element, and in particular, in an obstacle detection device such as a mobile work robot, one ultrasonic sensor is used. In order to detect an object in a wide range (wide angle), a horn is not used, and a means for separately providing ultrasonic transducers for transmission and reception is used so as to detect a short distance. Further, in a mobile work robot having this, a plurality of ultrasonic sensors are arranged around the main body.

[0003]

However, even if an object with a wide angle and a short distance is detected by such a conventional ultrasonic sensor, it is transmitted from an ultrasonic transducer for transmission (hereinafter, a transducer for transmission). The ultrasonic waves generated are diffracted by the baffle plate on the front side where the transmitting transducer is attached, and are directly received by the ultrasonic transducer element for reception (hereinafter referred to as the receiving transducer). There was a limit to the distance measurement because of the indistinguishability. Also, in a mobile work robot having this, it is sufficient to increase the number of ultrasonic sensors in order to detect obstacles in the entire area around the main body, but if the number is increased, the installation distance between the sensors will decrease and the installation space will decrease. However, the number of sensors is limited because the reflected wave or direct wave of a certain sensor cannot be received by another sensor and the obstacle cannot be detected accurately. Could not be detected and was in collision. In particular, the collision in the left and right corners in front of the main body was remarkable.

Therefore, the present invention is to solve the problems of the above-mentioned conventional structure, and to improve the mounting structure of the ultrasonic vibrating element to the baffle plate so that the vibrating element for transmission changes to the vibrating element for reception. A first object of the present invention is to provide an ultrasonic sensor capable of detecting a wide-angle object at a short distance by reducing direct waves to the ultrasonic sensor.

It is a second object of the present invention to provide a mobile work robot capable of avoiding collisions by eliminating the blind spots in the diagonally front part of the main body, which have a high frequency of collisions, by providing reflecting plates without increasing the number of ultrasonic sensors. .

[0006]

A first means of the present invention for achieving the first object has an ultrasonic transducer element for transmission or reception, and a pair of openings for arranging them in parallel. A baffle plate is provided, and the periphery of the opening of the baffle plate forms an edge portion having an acute angle with respect to the front surface of the baffle plate, and the rear surface of the edge portion does not block the opening area and the end portions are located at the same distance from the front surface. An ultrasonic sensor is provided in which the above-mentioned protrusions are provided, and the ultrasonic transducer for transmission or reception is brought into contact with the protrusions of the baffle plate and provided behind the edge of the peripheral edge of the opening. is there.

A second means of the present invention for achieving the second object is a driving means and a steering means for moving a main body, and a plurality of ultrasonic sensors for detecting an obstacle around the main body and measuring the distance. And a working control means for controlling the driving of the main body by controlling the driving means and the steering means, and a working means for performing cleaning and the like. The mobile work robot is characterized by being installed toward the front, and provided with a reflector plate which is located near the outside of the sensor and near the rear of the sensor and forms a substantially right angle with the front surface of the sensor.

[0008]

According to the first means of the present invention, an acute-angled edge portion is provided on the periphery of the opening of the baffle plate, and a projection portion is provided on the rear surface of the edge portion, and the ultrasonic transducer is brought into contact with the projection portion of the baffle plate. By arranging it behind the edge of the opening edge,
First, the installation position of the element is stable, and the ultrasonic waves diffracted at the peripheral edge of the opening are stochastically reduced, and the direct wave from the transmitting oscillator to the receiving oscillator is reduced. An ultrasonic sensor that can detect the object can be realized.

Further, according to the second means of the present invention, a part of the plurality of ultrasonic sensors constituting the distance measuring means for detecting an obstacle around the main body and measuring the distance is directed toward the diagonally front side of the main body. Installed on the outside of the sensor, and by providing a reflection plate near the outside rear of the sensor and forming a substantially right angle with the front surface of the sensor, a blind work area diagonally forward of the main body, which has a high frequency of collisions, can be eliminated, and collisions can be avoided. Can be realized.

[0010]

【Example】

(Embodiment 1) An embodiment of the first means of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows the configuration of the ultrasonic sensor of the present invention. In the figure, 41 is an ultrasonic transducer for transmission, 42
Is an ultrasonic vibrating element for reception, which has the same structure in which a vibrating body made of a piezoelectric element such as ceramic is housed in a cylindrical case, and has an electric terminal 43 at the rear part of each.
・ 44 is derived. Reference numeral 45 is a baffle plate, which has a circular opening 4 at the front of each of the ultrasonic transducers 41 and 42.
It has 6.47. In addition, the baffle plate 45 is provided with cylindrical mounting portions 48 and 49 for mounting the ultrasonic vibration elements 41 and 42.
1.42 is a vibration damping material 50 made of foam rubber or felt
Mounted inside this via 51. Baffle board 5
As shown in FIG. 1A, the peripheral edges of the openings 46 and 47 of the edge portions 46 ′ and 46 ′ of the acute angle α with respect to the front surface of the baffle plate 45.
47 '. Further, on the rear surfaces of the edge portions 46 'and 47', the center of each of the openings 46 and 47 does not project into the circle of the openings 46 and 47 (that is, the opening area is not blocked), and 120
Small protrusions 52 and 53 are provided at three intervals with respect to the peripheral lengths of the edge portions 46 ′ and 47 ′, and their end faces are located at the same distance L from the front face of the baffle plate 45. The ultrasonic vibration elements 41, 42 are attached to the end faces of the protrusions 52, 53 from the rear side of the baffle plate 45 so that a gap L is formed behind the edge portions 46 ', 47'. . Reference numerals 54 and 55 are cap covers that cover the rear portions of the ultrasonic transducers 41 and 42, and sound absorbing materials 56 and 57 made of sponge, foamed rubber, or the like are provided in the space inside the cap covers. Reference numerals 58 and 59 denote lead wires of the ultrasonic transducers 41 and 42, respectively, which are connected to the electric terminals 43 and 44.

The operation of the ultrasonic sensor configured as described above will be described below. The ultrasonic sensor of the present embodiment drives the ultrasonic transducer 41 for transmission to transmit the ultrasonic pulse A, and receives the reflected wave B which is reflected by the ultrasonic pulse A hitting an object in front and returning. The ultrasonic vibrating element 2 for use in reception detects the distance to the object by measuring the time difference between the transmission time and the reception time. When the distance to an object at a short distance is detected by this distance measuring method, if the ultrasonic pulse transmitted from the ultrasonic transducer element 1 for transmission strongly enters the ultrasonic transducer element 42 for reception, the ultrasonic wave element 42 is transmitted from the object. Distance cannot be measured because it cannot be distinguished from the reflected wave. Therefore, in this embodiment, the direct wave from the transmitting ultrasonic transducer 41 to the receiving ultrasonic transducer 42 is reduced by the means described below.

FIG. 2 illustrates the operation of the first means. 2A shows an ultrasonic vibrating element 41 for transmission, and 61 is a vibrating body inside the ultrasonic vibrating element 41. The vibrating body 61 is driven and vibrates to generate ultrasonic waves. Here, there are the following three types of ultrasonic waves generated from the point P, for example. One is to go out directly from the opening 6 as shown by an arrow a. The second one is the one that is diffracted by the edge portion 46 'of the opening 46 and goes out as shown by the arrow b. The third one is one that is reflected inside the opening 6 and does not go outside as shown by an arrow c. Among these, the transmitting oscillator 1 to the receiving oscillator 42
The second diffracted wave may be a direct wave to the edge. However, in this embodiment, the edge portion 46 ′ has an acute angle, and the ultrasonic wave vibrating element 41 for transmission abuts on the protrusion 52 to form an edge. Since it is behind (distance L) from the portion 46 ', it can be seen that only the light passing through the tip portion of the edge portion 46' causes diffraction (that is, if the edge portion is a right angle, the reflection as shown by the arrow c). Not all will be diffracted). Furthermore, the protrusion 52 not only maintains the distance L, but also can perform accurate and stable positioning support of the front surface of the ultrasonic transducer 41 for transmission parallel to the front surface of the baffle plate 45. If the element front surface is inclined with respect to the front surface of the baffle plate 45, the front direction of the vibrating body 61 approaches the edge portion 46 'in the slanting direction, but the energy density of ultrasonic waves transmitted from the vibrating body 61 is In the inclined direction, high-energy ultrasonic waves are diffracted through the tip portion of the edge portion 46 'because the height is higher the closer to the front direction. That is, the probability that the ultrasonic wave transmitted from the ultrasonic transducer 41 for transmission will be diffracted by the edge portion 46 ′ having the acute angle α and the protrusion 52 on the rear surface becomes very small.

Further, as shown in FIG. 2B, when the ultrasonic vibrating element 42 for reception is examined, for example, the direct wave d from the ultrasonic vibrating element 41 reaches the opening 47 and the edge portion 47. When hitting ', since the edge portion 47' has an acute angle, the diffraction direction here is in the outer peripheral direction of the ultrasonic transducer element 42 for reception, and therefore does not directly reach the vibrating body 62. Further, the protrusion 53 supports the front surface of the ultrasonic transducer element 42 for reception in parallel with the front surface of the baffle plate 45 in accurate and stable positioning, and the ultrasonic transducer element 42 is inclined and has high reception sensitivity. The front direction of the vibrating body 62 is prevented from approaching the edge portion 47 ′. That is, even if the ultrasonic transducer 4
Even if a direct wave is emitted from 1 along the surface of the baffle plate 45, the adverse effect due to this can be reduced by the acute-angled edge portion 47 ′ and the projection portion 53.

Thus, the opening 46 of the baffle plate 45 is
The edge portions 46 'and 47' of the acute angle α formed on 47
Protrusions 52.5 provided on the rear surface of the edges 46 '/ 47'
By 3, the direct wave from the ultrasonic vibration element 41 to the ultrasonic vibration element 42 is reduced.

In order to bring out the above effects sufficiently, the thickness of the tips of the edge portions 46 'and 47' is 0.5 mm or less,
The size of the gap L is preferably about 1 to 3 mm. In addition, the number of the protrusions 52 and 53 and the arrangement interval are set so that the ultrasonic transducer 41
The limitation is not limited as long as 42 can be positioned accurately and stably.

(Embodiment 2) The overall construction of a self-propelled cleaner as an embodiment of the first means of the present invention will be described below with reference to FIGS. 3 and 4. 1 is the main body of the self-propelled vacuum cleaner, 2L and 2R
Are drive wheels respectively provided on the left and right rear sides of the main body 1, and are driven independently by the drive motors 3L and 3R. Reference numeral 4 is a subordinate wheel rotatably attached to the front of the main body 1. As described above, the drive wheels 2L and 2R, the drive motors 3L and 3R, and the driven wheel 4 constitute drive means and steering means for moving the main body 1. In addition, 3L 'and 3R' are rotation detectors including rotary encoders connected to the drive motors 3L and 3R, respectively.
It constitutes the moving distance measuring means, and includes drive motors 3L and 3L.
The number of rotations of the shaft of R is detected (hereinafter referred to as moving distance measuring means 3 '). Reference numeral 5 is a door provided on the rear surface of the main body, which opens vertically with the lower part as a fulcrum. Reference numeral 8 denotes a telescopic handle, which is in the state shown in the figure at the time of automatic cleaning, but when the main body 1 is manually moved, it is extended upward along the longitudinal direction of the pipe (a part of the telescopic handle 8) inside the main body 1. (Not shown). Reference numeral 11 denotes a cushioning member made of an elastic material attached to the periphery of the main body 1 for cushioning the impact when the main body 1 collides with an obstacle. Reference numeral 12 denotes a contact detection unit that projects from the main body 1 from the side portion to the front portion of the main body 1, and can detect contact with obstacles such as wall surfaces on the front and side of the main body, and projections and steps from the floor surface. Reference numeral 13 denotes a movable body provided at the left and right rear corners of the main body 1, and when contacted with an obstacle or the like, the movable body 13 is pushed inside the main body 1 to detect the contact. Reference numeral 14 is an electric blower, 15 is a dust collecting chamber, and 16 and 17 are filters provided therein.
A floor nozzle 18 is provided at the bottom rear of the main body 1, and is connected to the dust collection chamber 15 via a connection pipe 19. Reference numeral 20 denotes a brush, which is planted around the rotary plate and rotationally driven inwardly of the main body 1 substantially parallel to the floor surface by a motor provided in the main body 1 to sweep dust on the floor surface. that's all,
The electric blower 14, the dust collection chamber 15, the filters 16, 17, the floor nozzle 18, the connecting pipe 19, and the brush 20 constitute cleaning means. Reference numeral 22 is a distance measuring means for measuring the distance from the front of the main body 1 to the left and right sides, and the ultrasonic sensors capable of transmitting and receiving are arranged as shown in FIG. It is composed by.
Reference numeral 23 is a direction measuring means for measuring the direction of the main body 1, and in this embodiment, it is composed of a rate gyro and an integrator for integrating the output. Reference numeral 21 is a travel control means for controlling the drive motors 3L and 3R on the basis of information from the distance measuring means 22, the direction measuring means 23 and a guide signal receiving means 26 which will be described later to control the travel of the main body 1. Reference numeral 29 is a power source composed of a storage battery for supplying electric power to the whole. A power receiving means 25 receives power from a charger (which is different from the main body 1 and is not shown) at the time of charging, supplies the power to a power source 29, and is protected by a back plate 5 ′ attached to the door 5. There is. Reference numeral 26 is an induction signal receiving means for receiving an induction signal from a transmitter (which is different from the main body 1 and not shown). Reference numeral 27 is an operation button provided on the operation unit 28. Reference numeral 40 denotes a reflecting plate which is arranged in a diagonally forward direction of the main body 1 and which is close to the outside rear of the ultrasonic sensor (e of the distance measuring means 22), and its front surface is substantially perpendicular to the sensor front surface (angle β in the figure). It is also provided along the vertical direction.

The operation of the self-propelled cleaner constructed as above will be described below. FIG. 5 shows an enlarged view of the left front portion of the main body 1 and obstacles (S1, S2, S3). When the self-propelled vacuum cleaner of this embodiment is actually used, there are many protrusions from the wall surface of the pillars, furniture, etc. in the room, and the obstacle S
Situations such as 1.S2.S3 occur frequently. First, the obstacle S1 on the front side of the main body 1 is an ultrasonic sensor installed in the front direction when the main body moves forward (D1 direction) or moves diagonally forward (D2 direction). This can be detected, distance measured, and avoided by u1. Next, for the obstacle S2 diagonally in front of the main body 1, when the main body moves forward, it does not come into contact with the main body even if it cannot be detected. With the ultrasonic sensor e installed, the ultrasonic wave path u
This can be detected, distance measured, and avoided by 2. However, S
As for the obstacle S3 located between 1 and S2, the ultrasonic wave transmitted from the ultrasonic sensor e is reflected in the direction away from the main body at S3 (its route is u3 ′), and therefore cannot be received. When S moves in the D2 direction, there is a possibility that S3 can be detected, but when it moves in the D1 direction, it cannot detect and collides. Therefore, when the reflection plate 40 is provided, the transmitted ultrasonic waves from the ultrasonic sensor e can be reflected by the reflection plate 40 first and then directed perpendicularly to the surface of the obstacle S3, and then reflected waves from S3. Returns to the ultrasonic sensor e in the same route as the transmission in the opposite direction (the route is u3), so that the obstacle S3 can be detected.

That is, the reflector 40 can detect the obstacle S3 while ensuring a state in which the obstacle S2 can be detected by using only the ultrasonic sensor e without increasing the number of ultrasonic sensors. .

The exact direction and size of the reflector 40
The position is adjusted by the orientation, sensitivity, size of the ultrasonic sensor e, the distance between the ultrasonic sensor e and the buffer 11 or the contact detection means 12, and the like.

[0021]

As described above, according to the first means of the present invention, an ultrasonic vibrating element for transmission is provided by an acute-angled edge portion formed in the opening of the baffle plate and a protrusion provided on the rear surface of the edge portion. Direct waves to the ultrasonic transducer for reception are reduced, and wide-angle and short-distance objects are detected that are optimal for obstacle detection devices and range finding devices of mobile work robots such as automatic floor cleaners and automated guided vehicles. The ultrasonic sensor that can be realized can be realized.

Further, according to the second means of the present invention, a part of the ultrasonic sensor constituting the distance measuring means is installed so as to be directed obliquely to the front of the main body, and is located on the front surface of the sensor in the vicinity of the outer rear of the sensor. By providing a reflection plate that forms a substantially right angle with respect to the main body, it is possible to realize a mobile work robot that eliminates the blind spot of the distance measuring means from diagonally front to the front of the main body and can reliably detect and avoid obstacles.

[Brief description of drawings]

FIG. 1A is a longitudinal sectional view of an ultrasonic sensor which is an embodiment of a first means of the present invention. FIG. 1B is a view taken in the direction of arrow X in FIG. 1A.

FIG. 2A is a vertical cross-sectional view of the vicinity of an ultrasonic transducer element for transmission for explaining the operation of the embodiment. FIG. 2B is a vertical sectional view of a vicinity of the ultrasonic transducer element for reception for explaining the operation of the embodiment.

FIG. 3 is a vertical sectional view of a mobile work robot that is an embodiment of the second means of the present invention.

FIG. 4 is a cross-sectional view of the mobile work robot of the same embodiment.

FIG. 5 is a diagram showing an operation of the embodiment.

[Explanation of reference numerals] 1 main body 2 drive wheel 3 drive motor 4 driven wheel 14 electric blower 15 dust collection chamber 16 filter 17 filter 18 floor nozzle 19 connection pipe 20 brush 21 travel control means 22 distance measuring means 40 reflector 41 super for transmission Sound wave vibrating element 42 Ultrasonic wave vibrating element for reception 45 Baffle plate 46/47 Opening portion 46 '/ 47' Edge portion 52/53 Projection portion

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Osamu Eguchi 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Hirofumi Inui, 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd.

Claims (2)

[Claims] 1. An ultrasonic vibration element for transmission or reception, and a baffle plate having a pair of openings for arranging the ultrasonic vibration elements in parallel, the opening peripheral edge of the baffle plate having an acute angle with respect to the front surface of the baffle plate. The edge is formed, and the end is located at the same distance from the front without blocking the opening area on the rear of the edge. 3
An ultrasonic sensor in which projections at more than one place are provided, and the ultrasonic transducer element for transmission or reception is placed behind the edge of the peripheral edge of the opening so as to abut the projection of the baffle plate. 2. A drive means and a steering means for moving the main body, a distance measuring means comprising a plurality of ultrasonic sensors for detecting obstacles around the main body and measuring the distance, and the drive means and the steering means. It is equipped with a traveling control means for controlling the traveling of the main body and a working means for performing work such as cleaning.A part of the ultrasonic sensor is installed diagonally forward of the main body, and is located close to the outside rear of the sensor. A mobile work robot equipped with a reflector that makes an angle of approximately right with the front of the sensor.