JPS6177774A - Obstacle detector - Google Patents

Abstract

PURPOSE:To enable the detection of the position of an obstacle with a single frequency, by receiving the reflected light of an ultrasonic wave with two receives for arithmetic processing when the ultrasonic wave from one transmitter is reflected on an obstacle. CONSTITUTION:A transmitter 4 and a receiver 6 are brought so close to each other that the distance r1 is always regarded as the same both between an ultrasonic wave transmitter 4 and an obstacle 1 and a receiver 6 and the obstacle 1 and an additional receiver 7 is arranged at a distance R from the centers of the transmitter 4 and the receiver 6 while the distance between the receiver 7 and the obstacle 1 is set at r2. Then, when the times are represented by t1 and t2 representatively until a transmission ultrasonic wave is reflected on the obstacle 1 and received with receivers 6 and 7, r1 and r2 are determined with an arithmetic circuit 3. The X axis and Y axis are set based on a specified positional relationship between the transmitter 4 and the receivers 6 and 7 and a specified computation is performed with the circuit 3 based on the relationship between distances r1, r2 and R to determine the position of the obstacle 1.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an obstacle detection device using ultrasonic waves.

2. Description of the Related Art Obstacle detection devices using ultrasonic waves have been known as devices for detecting obstacles. As shown in Fig. 2, the transmitter 4 and receiver 6 and the transmitter 5 and receiver 7 are paired, and the paired transmitters and receivers are arranged without any separation between each pair. Piping is done at a certain interval R.
Also, the transmitter 4 and the transmitter 5 emit ultrasonic waves of different frequencies, and only the receiver 6 (or 7) paired with the transmitter 4 (or 5) receives the ultrasonic waves of that frequency. However, receivers 7 (or 6) that are not paired do not receive signals. As a result, obstacle 1 and transmitter 4,
The distance r1 between the receiver 6 and the distance r2 between the obstacle 1, the transmitter 5, and the receiver 7 are determined, and the relationship between these distances r1 and r2 and the distance R between each transmission and reception is calculated by an arithmetic circuit. The position of the obstacle is determined by

Problems to be Solved by the Invention In the above-mentioned obstacle detection device, two types of ultrasonic waves with different frequencies must be used, so it is necessary to separate the two-frequency signals and to use the two frequencies. This method has the disadvantage that differences in decomposition ability must be taken into consideration.

Means for Solving the Problems In order to solve the above problems, the present invention provides a method for emitting ultrasonic waves.
The system is characterized by the use of two transmitters, two receivers that receive the ultrasonic waves reflected back from obstacles, and an arithmetic circuit that receives the output signals of the receivers and calculates the position of the obstacle.

Effect: The present invention has the above-mentioned characteristics, so that it is possible to detect the position of an obstacle using only a single frequency.

Example An embodiment of the present invention will be explained with reference to FIG.

The transmitter 4 and the receiver 6 are brought close to each other to the extent that the distance between the ultrasonic transmitter 4 and the obstacle 1 and the distance between the receiver 6 and the obstacle 1 can always be regarded as the same distance r1, and the other one receiver 7 is placed at a distance R from the center of the transmitter 4 and receiver 6, and the distance between the receiver 7 and the obstacle 1 is rl. Assuming that the time it takes for the ultrasonic wave transmitted from the transmitter 4 to be reflected by the obstacle 1 and received by the receivers 6 and 7 to be tl and t2, respectively,
Since the speed of sound in the air is 340 m/s, the relationship between distance r1 and rl is 2 rl = 340 t,, r, + r 2
= 340 t2. This relational expression is solved by the arithmetic circuit 3 to obtain rl and rl.

Also, place the X axis with the direction from receiver 6 to receiver 7 positive on the line connecting the transmitter 4 and receivers 6 and 7, and place the X axis between the center of the transmitter 4 and receiver 6 and the receiver 7. y with the detection direction taken in a positive direction perpendicular to the X axis from a position 1/2R distance away from
Place the axis.

Note that the origin is the intersection of the X axis and the y axis.

By determining the X-axis and y-axis in this way, the arithmetic circuit 3
From the distance R between rlsr2, the center of transmitter 4 and receiver 6, and receiver 7, the x coordinate of the position with obstacle 1 is (r knee r2') / 2 R, and the y coordinate is two((
-R-2~'+-rF -rX)/2RJ"l. By performing this calculation in the arithmetic circuit 3, one transmitter 4, two receivers 6 and 7, and the arithmetic circuit 3 can be used. This makes it possible to determine the position of the obstacle 1 using single-frequency ultrasonic waves.

Effects of the Invention As described above, by implementing the present invention, it is no longer necessary to take into account the difference in resolution in determining the position of an obstacle using a single frequency ultrasound.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing one embodiment of the present invention, and FIG. 2 is an explanatory diagram of a conventional obstacle detection device.

Claims (1)

[Claims] Equipped with one transmitter that emits ultrasonic waves, two receivers that receive the ultrasonic waves that are reflected back from obstacles, and an arithmetic circuit that receives the output signals of the receivers and calculates the position of the obstacle. An obstacle detection device featuring: