JPS62116205A - Ultrasonic sensor - Google Patents

Abstract

PURPOSE:To accurately detect the distance from a robot to an obstruction, by providing an ultrasonic transmitter and an ultrasonic receiver to he robot so that both of the are spaced apart from each other in a height direction and the sensitivity characteristic center line of the transmitter and the received cross that of the receiver. CONSTITUTION:An ultrasonic receiver 2 is arranged to the upper end part of the side surface of a self-supporting running robot 10 and an ultrasonic transmitter 13 is arranged to the lower end part of the side surface of said robot 10. The time from the point of time when an ultrasonic wave was emitted from the transmitter 13 to the point of time when the reflected wave thereof is received by the receiver is measured on the basis of a reference clock to be sent to the control part provided to the main body of the robot 10. The distance between the robot 10 and a obstruction is calculated on the basis of the calculated number of clock pulses. Herein, the transmitter 13 and the receiver 12 are set so that the center liens (l), (m) of receiving sensitivity characteristics respectively cross the straight line (n) connecting the receiver 12 and the transmitter 13 in the vertical direction at predetermined angles theta1, theta2 obtained experimentally. By this method, the obstruction detecting error in the vertical direction along the side surface of the robot 10 is improved to a large extent. Therefore, the obstruction detectable region in the height direction of the robot 10 is widened in the vertical direction and the distance between the robot and the obstruction can be measured with high accuracy regardless of the shape and the higher of the obstruction.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention 1] The present invention relates to an ultrasonic sensor device for detecting obstacles in an autonomous robot.

[Prior Art and its Problems] Conventionally, some self-supporting robots with a three-dimensional external housing are equipped with an ultrasonic sensor device for detecting obstacles, which serves as the robot's eyes. In this type of robot, the method of detecting obstacles is as follows:
°) to scan around the robot; (b) to scan around the robot by arranging multiple ultrasonic sensor devices with narrow directivity around the robot in the same horizontal plane; (c) to scan around the robot in (b) above. Method + (b) For example, ultrasonic sensors with narrow directivity are arranged in four directions (equal angles of 90°), and each sensor scans within 90° of a horizontal plane. These methods provide the desired obstacle detection ability in each direction within the same horizontal plane. However, little consideration has been given to the ability of a three-dimensional robot to detect obstacles in the vertical direction (height direction).

That is, in the conventional ultrasonic sensor device, as shown in FIG. It consisted of a device 3 and an ultrasonic receiver 4. The minimum detectable distance +11LHIN of the ultrasonic sensor device 2 is determined by the processing speed of the circuit that processes the electrical signals of the ultrasonic sensor device 2, that is, the time from the emission of the ultrasonic wave to the reception of the reflected sound wave is extremely short. (If an obstacle is extremely close to the robot), circuits with slow calculation speeds will not be able to catch up, making it impossible to detect it. Also, the maximum detectable distance L MAX is determined by the intensity of the reflected wave, that is, the energy of the ultrasonic wave is attenuated in proportion to the distance to the obstacle, and is greatly attenuated depending on the angle of reflection, so it is determined particularly by the output standard of the ultrasonic transmitter 3. It was decided. Furthermore, since the ultrasonic transmitter 3 and the ultrasonic receiver 4 are disposed extremely close to each other (integrated at approximately the same position), such an ultrasonic sensor device as shown in FIG. The equidistant lines from the transmitter 3 and receiver 4 in 2 (actually a spherical surface, but shown as a line in 2) are equicentric circles rl, r2, r centered on the ultrasonic sensor device 2.
The arc of 3... is considered to be approximately one point, and the ultrasonic sensor device &! Each distance from t2 does not accurately represent the distance from the upper end X or lower end W of robot I to the obstacle because robot l is a housing.
Therefore, if obstacles a, b, and c are located separately at a distance 5 (=r+) from the outer surface of robot 1, the distance r1 to obstacle a in the same horizontal plane as ultrasonic sensor device 2 is accurate. However, the collision between the outer surface of the robot 1 and the obstacle S, c located above or below the ultrasonic sensor device 2 is recognized as a value larger than the distance rl. Therefore, when the robot l moves, there is a risk that the obstacles S and C will collide with the upper end X or the lower end W of the robot I. The recognition error due to this robot l becomes larger as the obstacle is closer to the robot l, and the recognition error due to the distance r2. r3...
...and it gets smaller as it gets further away. Therefore, an obstacle-detectable area 5 and an obstacle-undetectable area 6 as shown in FIG. 6 appeared. In order to eliminate this problem, it is necessary to provide a large number of ultrasonic sensor devices 2 in the vertical direction on the outer surface of the robot 1, which has the disadvantage that the control circuits associated with them also increase, making the robot 1 expensive.

[Objective of the invention 1 This invention was made in view of the above-mentioned circumstances,
The purpose is to use a small number of ultrasonic transmitters and
To provide an ultrasonic sensor device that can accurately detect the distance from a robot to an obstacle with a receiver regardless of the height and shape of the obstacle and has a wide obstacle detection area.

[Summary of the Invention] In order to achieve the above-mentioned object, the present invention provides a robot with an ultrasonic transmitter and an ultrasonic receiver that are spaced apart from each other in the height direction, and whose sensitivity characteristic center line and receiver The gist is that the center line of the sensor's sensitivity characteristics is intersected with the center line of the sensor.

[Embodiment 1] Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. 1 to 5. In Fig. 1, IO is a housing-shaped autonomous robot, and the bottom of the autonomous robot IO is equipped with wheels for movement, so that it can move freely on the floor under the control of a control device. There is. autonomous running robot l
An ultrasonic receiver 12 is disposed at the upper end of the side surface of O, and an ultrasonic transmitter 13 is disposed at the lower end of the side surface. In the figure, one set of ultrasonic transceivers 12.13, that is, an ultrasonic sensor device, is shown to simplify the explanation, but in reality, there are multiple sets of ultrasonic transceivers 12.13 on the outer circumferential surface of the robot. They are arranged separately at the upper and lower ends of each other. The configuration of these ultrasonic sensor devices consists of a circuit as shown in FIG. In the figure, a timing generation circuit 14 is a circuit that generates a transmission start time, its rising timing, and a signal for starting a timer 15. The drive circuit 16 is made up of transistors, transformers, etc., and voltage amplifies the 40KH7 signal input from the oscillation circuit 18 via the AND gate 17, and drives the plurality of ultrasonic transmitters 13 with the signal to oscillate ultrasonic waves. . The ultrasonic wave reflected by the obstacle and returned is received by the ultrasonic receiver 12, converted into an electrical signal, and input to the reception amplification circuit 19 where it is amplified. This receiving amplifier circuit 19 is made up of an operational amplifier, etc., and its output signal is given to an OR circuit 2° including a Schmitt trigger circuit, etc., and this output signal is inputted as a stop signal to the timer 15. The timer 15 is driven by a reference clock pulse φ (the minimum detectable pressure +
11LMIN is determined), the time from when the ultrasonic wave is emitted from the ultrasonic transmitter 13 to when the reflected wave is received by the ultrasonic receiver 12 is measured by the reference clock pulse φ, and the time is measured by the reference clock pulse φ. The information is sent to the provided control unit. Then, the distance between the robot 10 and the obstacle is calculated using the measured number of clock pulses φ.

Here, the maximum detectable ratio 1111 L M^X is determined by the output standard of the drive circuit 16. This means that the emitted ultrasonic waves are reflected from the surface of the obstacle and are sent to the ultrasonic receiver 1.
This is because the signal is attenuated by the time it reaches 2, so even if it is amplified by the reception amplifier circuit 19, if the OR circuit 20 has a low S/N ratio, the obstacle cannot be identified.

FIG. 3 shows the arrangement of the ultrasonic receiver 12 and the ultrasonic transmitter 13 in the ultrasonic sensor device according to the present invention, and the center edge of their receiving sensitivity characteristics, m, is the ultrasonic receiving sensitivity. A straight line n vertically connecting the device 12 and the ultrasonic transmitter 13 (this straight line n is approximately the same as the vertical surface of the outer surface of the robot 1) and 0
They do not seem to intersect at angles of 1 and θ2, respectively.

In the figure, an autonomously running robot (10) of an ultrasonic receiver 12 is shown.
If the mounting position of the ultrasonic transmitter 13 on the autonomous robot 10 is W, then the equidistant lines from the receiver 12 and the transmitter 13 are R1, R2, . . . (It is actually an ellipsoid, but it appears as a line on the vertical plane.

).

Now, the error in detecting obstacles in the vertical direction along the side of the robot I will be specifically considered based on FIG. First, for comparison, when the conventional ultrasonic sensor device, that is, the ultrasonic transmitter/receiver is located at point C in the figure, the difference in measurement distance between the upper point D and the horizontal point F is the round trip path of the ultrasonic wave. Therefore, the distance between the receiver and transmitter is Ll, and the distance from the robot to the obstacle is L2.
Then, 2 plates - 2 drunkenness = 2 (L+/2) 2 +L22-
2L2...(1) On the other hand, in the example, the transmitter is placed at point B at the bottom end, and the receiver is placed at point A at the top end, so at the same point and the same point F. The difference in measurement distance is (BD+OA) - (BF+FA) = (57-〒L2
2 +L2)-2RT ■ 10,110,000 koku 10
...(2), where, for example, Ll=15C
Assuming I, L2=90CI.

The conventional measurement distance error is E14.9cm from formula (1).
...(3) The measurement distance difference of the present invention is 11.4 cm from formula (2)...
...(4) Therefore, according to the present invention, the error in detecting obstacles in the vertical direction along the sides of the robot is greatly improved.

The angle θl at which the ultrasonic transmitter 13 is attached to the robot 1 and the angle θ2 at which the ultrasonic receiver 12 is attached to the robot 1 are determined as follows. In Fig. 5, the maximum distance at which an obstacle can be detected is LM^×, the minimum distance is LHIN, and the distance between the ultrasonic receiver 12 and the ultrasonic transmitter 13 in the vertical direction is Ll.
Now, if we look at the sensitivity characteristic line and assume that the intersection of m is brought to the center (center of gravity) G of the plane area of (LMAX-LMrN) XL+, then from Fig. 5, approximately ta can be obtained.
n θo = L+/2÷ (LMAX-LMIN)
/2 holds true, 1°-θo = tan-' (Ll/ (LM^X
-LHIN)).

For example, =90c1, LMAX = 150cm, L
If HIN = 10 cm, θo is 29.4 degrees.

Based on the value of θ0, in order to expand the detectable region vertically near the distance LMIN, θ0 may be increased. In this way, we experimentally found the best 00 to suit the operation of the robot l, that is, the mounting angles θ1-90-00 and θ2=90-00 of the ultrasonic receiver 12 and the ultrasonic transmitter 13 of the robot l. can be determined.

[Effects of the Invention 1] As described in detail below, the ultrasonic sensor device of the present invention has its transmitter and receiver separated in the height direction and installed so that their center lines of sensitivity characteristics intersect. The area in which obstacles can be detected in the height direction expands vertically, and the shape of the obstacle increases.

The effect is that the distance can be measured with high precision regardless of the vertical position.

[Brief explanation of drawings]

Figure 1 shows the first embodiment of the present invention, and is a side view of the arrangement of the a'rf wave sensor attached to the robot, Figure i2 is a block circuit diagram of the ultrasonic sensor, and Figure 3 is the equidistant line of Figure 2. Figures 4 and 5 are diagrams for detailed explanation of the present invention,
FIG. 6 and FIG. 7 are a side view of the arrangement of a conventional ultrasonic sensor and a diagram of its characteristic curve. 5... Obstacle detectable area, 8... Obstacle non-detectable area, 10... Autonomous robot, 12... Ultrasonic receiver, 13...
Ultrasonic transmitter, vertical... Ultrasonic receiver characteristic center line, m... Ultrasonic transmitter characteristic center line, 01...
...Angle between an autonomous robot and text, 02...
...The angle between the autonomous robot and m. Patent applicant Casio Computer Co., Ltd. Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] In an ultrasonic sensor device including a pair of ultrasonic transmitter and ultrasonic receiver provided on a robot, the ultrasonic transmitter and the ultrasonic receiver are provided spaced apart in the height direction of the robot, An ultrasonic sensor device characterized in that these sensitivity characteristic center lines are arranged so as to intersect with each other within an obstacle detectable area.