JPH10253757A - Ultrasonic distance-measuring apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultrasonic distance-measuring apparatus by which the existence of a failure can be diagnosed easily. SOLUTION: An ultrasonic distance-measuring apparatus is constituted of an ultrasonic sensor circuit 10, of a microcomputer 20 and of an alarm 25. An ultrasonic sensor 11, a high-pass filter(HPF) 12 which reduces a low-frequency signal from the ultrasonic sensor 11, an amplifier 13 which amplifies an output signal from the HPF 12, a comparator 14 and a transmission circuit 15 are installed at the ultrasonic sensor circuit 10. The ultrasonic distance- measuring apparatus monitors whether a dummy signal corresponding to receives waves to be output from the ultrasonic sensor 11 within 1msec since a transmission signal is output to the ultrasonic sensor circuit 10 is input us detected within 1msec or not. When the dummy signal is detected within 1msec, it is judged that the ultrasonic sensor circuit 10 is normal. When the dummy signal is not detected even after 1msec elapses, it is judged that the ultrasonic sensor circuit 10 is broken down, and the alarm 25 is operated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic distance measuring device for measuring a distance to an object by ultrasonic waves.

[0002]

2. Description of the Related Art Conventionally, this type of ultrasonic distance measuring apparatus has
When transmitting an ultrasonic wave from the ultrasonic sensor toward the object and receiving a reception wave reflected by the object, a transmission signal instructing the transmission of the ultrasonic wave is output to the ultrasonic sensor, and then the ultrasonic wave is used. Calculate the response time until detecting the received signal,
The distance to the object is measured based on the calculated response time.

[0003]

However, in the prior art, even if a failure has occurred in the ultrasonic distance measuring device, the user cannot easily check whether or not the ultrasonic distance measuring device has failed. Distance was treated as correct.

Accordingly, an object of the present invention is to provide an ultrasonic distance measuring device capable of easily diagnosing the presence or absence of a failure.

[0005]

In order to achieve the above object, an ultrasonic distance measuring apparatus according to claim 1 of the present invention comprises:
The ultrasonic sensor transmits an ultrasonic wave toward an object, and includes an ultrasonic sensor that receives a reception wave reflected by the object, outputs a transmission signal instructing the ultrasonic sensor to transmit the ultrasonic wave, and outputs the reception signal. An ultrasonic sensor circuit that detects a reception signal output from the ultrasonic sensor by receiving a wave, and measures a response time from outputting the transmission signal to detecting the reception signal. Based on the response time, the calculating means for calculating the distance to the object, the ultrasonic sensor, the ultrasonic sensor, the received wave within a predetermined time after receiving the transmission signal The ultrasonic sensor circuit has a function of outputting a corresponding dummy signal, and when the ultrasonic sensor circuit does not detect the dummy signal output from the ultrasonic sensor within a predetermined time, the calculating unit outputs the ultrasonic signal. And wherein the diagnosing and circuit is faulty.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an ultrasonic distance measuring apparatus according to the present invention will be described. FIG. 1 is a block diagram showing the configuration of the ultrasonic distance measuring device according to the embodiment. The ultrasonic distance measuring device includes an ultrasonic sensor circuit 10, a microcomputer 20, and an alarm 25. The ultrasonic sensor circuit 10 includes an ultrasonic sensor 11 and a high-pass filter (H) for reducing low-frequency signals from the ultrasonic sensor 11.
A PF) 12, an amplifier 13 for amplifying an output signal from the HPF 12, a comparator 14, and a transmission circuit 15 are provided.

The transmission circuit 15 includes a microcomputer 20
An ultrasonic transmission signal is output to the ultrasonic sensor 11 in accordance with the transmission signal from. The ultrasonic sensor 11 is a transmission circuit 15
And transmits an ultrasonic wave toward an obstacle (object) in accordance with the ultrasonic transmission signal from the mobile phone, and receives a reception wave reflected by the obstacle. The ultrasonic sensor 11 outputs a dummy signal corresponding to a received wave to the HPF 12 within a predetermined time (1 msec in the present embodiment) after transmission. The comparator 14 determines that the output signal from the amplifier 13 is a predetermined value (2.
5V), and if so, an H level signal is output to the microcomputer 20.

The microcomputer 20 is composed of a well-known one-chip microcomputer. The microcomputer 20 outputs a transmission signal to the transmission circuit 15, receives a reception wave reflected by an obstacle, and outputs an H level signal from the comparator 14. The distance to the obstacle is measured based on the response time until.
Further, the microcomputer 20 determines whether or not the output signal of the comparator 14 becomes the H level within 1 msec after outputting the transmission signal to the transmission circuit 15 and diagnoses the failure of the ultrasonic sensor circuit 10. Do.

The alarm device 25 is connected to the microcomputer 20 and issues an alarm in accordance with an alarm device activation signal from the microcomputer 20.

FIG. 2 is a flowchart showing a processing procedure of a distance measurement program incorporated in the microcomputer 20. First, the microcomputer 20 outputs a transmission signal to the transmission circuit 15 (Step S1). Thereafter, a failure diagnosis process is performed to determine whether the ultrasonic sensor circuit 10 has failed (step S2).

FIG. 3 is a flowchart showing the procedure of the failure diagnosis process in step S2. First, it is determined whether or not the output signal of the comparator 14 has become H level based on the dummy signal output from the ultrasonic sensor 11 (step S).
11). When the output signal of the comparator 14 becomes H level, the process is terminated assuming that the ultrasonic sensor circuit 10 is normal. On the other hand, when the output signal of the comparator 14 does not become the H level, it is determined whether or not a predetermined time (1 ms in the present embodiment) has elapsed since the output of the transmission signal (step S12). If the specified time has not passed,
Returning to the process of step S11, if the predetermined time has elapsed, an alarm device operation signal is output to the alarm device 25 (step S13), and the process ends.

As described above, when a failure occurs in the ultrasonic sensor circuit 10, the output signal of the comparator 14 does not become H level within 1 msec.
0 outputs an alarm activation signal to the alarm 25, and returns to the processing program of FIG. On the other hand, if no failure has occurred,
The process returns to the processing program of FIG.

Then, a response time from when the transmission signal is output to when the reception wave reflected by the obstacle is received is calculated (step S3), and a distance is calculated from the response time (step S4). Thereafter, a time adjustment is performed to set the interval for outputting the transmission signal to a predetermined time (25 msec in this embodiment) (step S5), and the process returns to step S1.

As described above, in the ultrasonic distance measuring apparatus of the present embodiment, the dummy signal corresponding to the received wave output from the ultrasonic sensor 11 within 1 msec after the transmission signal is output to the ultrasonic sensor circuit 10 is output. It monitors whether or not it has been detected within 1 msec. If a dummy signal is detected within 1 msec, the ultrasonic sensor circuit 10 is determined to be normal. If no dummy signal is detected even after 1 msec has elapsed, When it is determined that the ultrasonic sensor circuit 10 is out of order, the alarm 25 is activated. Thus, the failure diagnosis of the ultrasonic sensor circuit 10 can be easily performed.

The failure diagnosis program can be executed when a distance measurement is instructed by a user or at predetermined time intervals by a timer process.

Further, when the vehicle is mounted on a vehicle, it is possible to immediately confirm whether or not the measured distance to the vehicle ahead is correct.

Further, it is also possible to measure the distance only when no failure has occurred, and to omit the distance measurement when a failure has occurred.

[0018]

According to the ultrasonic distance measuring apparatus according to the first aspect of the present invention, an ultrasonic sensor that transmits an ultrasonic wave toward an object and receives a reception wave reflected by the object is provided. An ultrasonic sensor circuit outputs a transmission signal instructing transmission of the ultrasonic wave, detects a reception signal output from the ultrasonic sensor by receiving the reception wave, and outputs the transmission signal by calculation means. After measuring the response time until the reception signal is detected, based on the measured response time, when calculating the distance to the object,
The ultrasonic sensor outputs a dummy signal corresponding to the reception wave within a predetermined time after receiving the transmission signal, and the ultrasonic sensor circuit outputs the dummy signal output from the ultrasonic sensor within a predetermined time. Otherwise, the calculating means diagnoses that the ultrasonic sensor circuit is faulty, so that it is possible to easily diagnose whether or not the ultrasonic sensor circuit including the ultrasonic sensor has a fault.

Furthermore, since the presence or absence of a failure is diagnosed before measuring the distance to the object, the user can immediately know whether or not the measured distance is correct.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an ultrasonic distance measuring device according to an embodiment.

FIG. 2 is a flowchart showing a processing procedure of a distance measurement program incorporated in the microcomputer 20.

FIG. 3 is a flowchart illustrating a failure diagnosis processing procedure in step S2.

[Explanation of symbols]

 10 Ultrasonic Sensor Circuit 11 Ultrasonic Sensor 20 Microcomputer 25 Alarm

Claims (1)

[Claims] 1. An ultrasonic sensor for transmitting an ultrasonic wave toward an object and receiving a reception wave reflected by the object, comprising: a transmitting signal for instructing the ultrasonic sensor to transmit the ultrasonic wave; An ultrasonic sensor circuit for outputting and detecting a reception signal output from the ultrasonic sensor by receiving the reception wave, and measuring a response time from outputting the transmission signal to detecting the reception signal. An ultrasonic distance measuring device comprising: a calculating unit that calculates a distance to the object based on the measured response time; wherein the ultrasonic sensor receives the transmission signal within a predetermined time. Having a function of outputting a dummy signal corresponding to the received wave, when the ultrasonic sensor circuit does not detect the dummy signal output from the ultrasonic sensor within a predetermined time,
The ultrasonic distance measuring device, wherein the calculating means diagnoses that the ultrasonic sensor circuit is out of order.