JP3126058B2 - Object detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a detector for detecting an object, and more particularly to an improvement in detection accuracy.

[0002]

2. Description of the Related Art Ultrasonic detectors, photoelectric detectors, proximity switches, and the like are used to detect the presence or absence of a detection target. For example, an ultrasonic detector emits an ultrasonic wave toward a detection target. If the detection target exists, the ultrasonic wave is reflected by the detection target and returns again. The presence or absence of a detection target is detected by detecting the reflected ultrasonic waves. That is, the reflected ultrasonic waves,
If it exceeds the predetermined value, it is determined that the detection target exists,
If it does not exceed the predetermined value, it is determined that there is no detection target.

[0003]

However, the conventional object detector as described above has the following problems. If there is disturbance (warm air, disturbance light, smoke, etc.) between the object detector and the detection target, the path of the emitted detection wave may fluctuate. As a result, the magnitude of the reflected detection wave fluctuates and may fluctuate above and below the threshold.
In such a case, the output with and without the detection target is repeated in a short time, despite the presence of the detection target. That is, there is a problem that an accurate detection result cannot be obtained.

[0004] In some cases, detection is performed based on changes in electrical characteristics (such as changes in capacitance and inductance) due to the presence of an object without using a detection wave. Even in such a detector, the detection output may become unstable due to disturbances such as noise and the presence of foreign matter other than the target object.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems and to provide an object detector capable of performing accurate detection without being affected by disturbance.

[0006]

According to a first aspect of the present invention, there is provided an object detector comprising: a wave transmitting means for emitting a detection wave toward an object; and a wave receiving means for receiving the detection wave transmitted from the wave transmitting means and reflected by the object. Means for outputting a signal having a reflected wave when the magnitude of the detection wave received by the receiving means exceeds a threshold value, and outputting a signal having no reflected wave when the magnitude of the detection wave is less than the threshold value First number calculation means for calculating how many times a signal with a reflected wave or a signal without a reflected wave is present out of the past n outputs including the current output from the determination means and the reflected wave determination means; A second number calculating means for calculating how many times a signal with a reflected wave or a signal without a reflected wave is present out of the past 2n to n + 1 outputs from the determining means;
The tendency calculating means for calculating the difference between the output of the number-of-times calculating means and the output of the second number-of-times calculating means, and infer the presence or absence of an object based on the output of the first number-of-times calculating means and the output of the tendency calculating means. Inference means for performing

The object detector according to claim 2 is characterized in that it outputs a detection output based on the output of the reflected wave determination means and the output of the inference means.

The object detector according to a third aspect is characterized in that the output of the inference means is extracted as a diagnostic output.

According to a fourth aspect of the present invention, the object detector includes a summing means for summing the magnitudes of the reflected waves received by the wave receiving means for a predetermined number of times, and the inference means takes into account the output of the summing means. It is characterized in that it makes inferences.

According to a fifth aspect of the present invention, there is provided an object detector for detecting a change in electrical characteristics due to the presence or absence of an object, and a signal having an output when an output from the detection circuit exceeds a threshold value. Output determination means for outputting a signal of no output when the output is equal to or less than the threshold value. Of the past n times of output including the current output from the output determination means, First number calculation means for calculating how many times the signal has occurred, n + from the past 2n times from the output determination means
A second number calculating means for calculating how many times a signal having an output or a signal having no output is output in one output;
The tendency calculating means for calculating the difference between the output of the number-of-times calculating means and the output of the second number-of-times calculating means, and infer the presence or absence of an object based on the output of the first number-of-times calculating means and the output of the tendency calculating means. Inference means for performing

According to a sixth aspect of the present invention, the object detector outputs a detection output based on the output of the output determination means and the output of the inference means.

[0012]

In the object detector according to the first aspect of the present invention, the number of times a signal having a reflected wave (absent) is present out of the past n outputs including the current output from the reflected wave determining means, and The number of times of the signal having the reflected wave (absent) out of the past 2n to n + 1 outputs from the determination means is calculated, and the output of the first number calculation means and the output of the second number calculation means are calculated. The difference is calculated, and the presence or absence of the object is inferred based on the output of the first number calculation means and the output of the tendency calculation means. Therefore, accurate detection can be performed even when the output of the reflected wave determination means is unstable due to disturbance.

The object detector according to claim 2 is characterized in that it outputs a detection output based on the output of the reflected wave determination means and the output of the inference means. Therefore, more accurate detection can be performed.

The object detector according to claim 3 is characterized in that the output of the inference means is extracted as a diagnostic output. Therefore, the degree of environmental change can be known from the diagnostic output.

According to a fourth aspect of the present invention, the object detector includes a summing means for summing the magnitudes of the reflected waves received by the wave receiving means for a predetermined number of times, and the inference means considers the output of the summing means. It is characterized in that it makes inferences. Therefore, more accurate detection can be performed.

According to a fifth aspect of the present invention, there is provided the object detector, wherein the output of the past n times including the current output from the output determining means is
It calculates how many times a signal with output (absence) has occurred and how many times a signal with output (absence) has occurred among the past 2n to n + 1 outputs from the output determination means. The difference between the output and the output of the second number calculation means is calculated, and the presence or absence of the target is inferred based on the output of the first number calculation means and the output of the tendency calculation means.

The object detector according to claim 6 is characterized in that it outputs a detection output based on the output of the output determination means and the output of the inference means. Therefore, more accurate detection can be performed.

[0018]

FIG. 1 shows an overall configuration diagram of an object detector according to an embodiment of the present invention. Here, an ultrasonic wave is used as a detection wave. The wave transmitting means 2 emits an ultrasonic wave toward the object 4. The ultrasonic wave reflected by the object 4 is received by the wave receiving means 6. The reflected wave judging means 8 judges whether or not the ultrasonic wave received by the wave receiving means 6 exceeds a threshold value, and if so, outputs a signal indicating the presence of an object. Signal.

The first number calculating means 10 calculates the number of times of the signal without the reflected wave out of the past n outputs including the current output from the reflected wave determining means. Also, the second
Is the number of past 2n from the reflected wave determination means.
It calculates how many times a signal without a reflected wave is present among the outputs from n times to n + 1 times. The tendency calculating means 14 receives the output of the first number calculating means and the output of the second number calculating means,
Calculate the difference between the two outputs. The inference means 16 infers the degree of environmental change (the degree of disturbance such as warm air) based on the output of the first number calculation means and the output of the tendency calculation means.

FIG. 2 shows a block diagram of an ultrasonic detector according to one embodiment. Microprocessor unit (MP
U) 32 outputs a control pulse at a predetermined interval (FIG. 3).
a). The oscillation circuit 24 receives this signal and outputs an oscillation signal (FIG. 3B). The drive circuit 22 outputs a drive signal according to the oscillation signal (FIG. 3C). Thereby, the ultrasonic vibrator 20 vibrates and emits ultrasonic waves.

The radiated ultrasonic wave is reflected by the object 4 and reenters the ultrasonic vibrator 20. This allows
The ultrasonic transducer 20 vibrates, and a reflected signal is received (α in FIG. 3D). In order to extract only the reflected ultrasonic waves, the MPU 32 converts the signal shown in FIG.
Has given to. Therefore, only the reflected signal α is extracted from the amplifier circuit 26.

After the envelope is extracted in the reflection signal α waveform shaping circuit 28, it is applied to a comparison circuit 30 (FIG. 3e). The comparison circuit 30 outputs an "object present" output only when the threshold value Th is exceeded (FIG. 3f). M
The PU 32 receives this output and outputs a detection output g (FIG. 3g).

When the object 4 does not exist, no ultrasonic wave is reflected, and no output is obtained from the comparison circuit 30. Therefore, the MPU 32 does not output the detection output g.

In this embodiment, in addition to the above output,
A fuzzy detection output terminal 40 is provided. Hereinafter, the fuzzy detection output will be described.

In FIG. 2, it is assumed that there is a disturbance between the ultrasonic vibrator 20 and the object 4 due to warm air or the like. As a result, the path of the ultrasonic wave may fluctuate, and the output of the comparison circuit 30 may become unstable (repeated between the presence and absence of the object). For example, assume that the output has changed as shown in FIG. The MPU 32 performs fuzzy inference based on the twelve outputs including the present, and determines the presence or absence of the target.

The MPU 32 first checks the past 6
Out of the outputs, how many times there was "no object" (E
_n ). In the same manner, the number of times (E _n−1 ) from the sixth to twelfth “no target” is calculated. FIG.
In the case shown in, E _n is 3, E _n-1 is also 3. Then, MPU 32 calculates the _{DE = E n -E n-1} . FIG.
In this case, DE = 0. Also, MPU32
Is the peak value v of the output from the waveform shaping circuit 28 for a predetermined number of times.
Is also calculated (see FIG. 3e).

Next, MPU 32, based on E _n, DE, S, performed whether the fuzzy inference object is present. E _n, DE, the membership functions of the fluctuation P is a membership function and the inference result of the S, shown in FIG. The fluctuation refers to the degree of being affected by disturbance. Here, E _n is large and small, DE is negative, 0, positive, S is the representation of the membership function in the certainty of SUM = 1, SUM = 0. SUM is a crisp function. That is, SUM = 1 when the sum S of the peak values exceeds a predetermined value, and SUM = 0 when the total S does not exceed the predetermined value. In another embodiment, this may be treated as a fuzzy function.

The rules used for the inference are as follows.

[0029] Rule 1: IF E _n = small AND DE
= 0 THEN P = rather small Rule 2: IF E _n = large AND DE = 0 THE
N P = fairly large Rule 3: IF E _n = small AND DE = positive THE
N P = small Rule 4: IF E _n = large AND DE = negative THE
N P = large Rule 5: IF E _n = small AND DE = negative THE
N P = medium-rule 6: IF E _n = large AND DE = positive THE
NP = medium The MPU 32 infers the degree of fluctuation P based on the above membership functions and rules. In this embodiment, inference was made by the MIN-MAX method. The inference result is expressed as a numerical value between 0 and 100 as the degree of fluctuation P by the centroid method.

When SUM = 0, inference is performed as described above. When SUM = 1, rule 5 is used.
Inference is performed by setting the likelihood of the consequent part of Rule 6 to 1. The reason for this is that when SUM is 1 and the peak value fluctuates rapidly, it should be determined that there is fluctuation. In another embodiment, SUM
When = 1, rules 5 and 6 may be changed as follows.

[0031] Rule 5: IF E _n = small AND DE
= Negative THEN P = large Rule 6: IF E _n = large AND DE = positive THE
NP = Large The MPU 32 determines the presence of the target based on the degree of fluctuation P. In this embodiment, if P is 26 or more, it is determined that an object exists, and if P is less than 26, it is determined that no object exists. Therefore, even if there is fluctuation, the presence of the target can be accurately determined. The determination output is output from the terminal 40 via the output circuit 36.

In another embodiment, the degree of fluctuation P may be directly output as a diagnostic output. As a result, the degree of environmental change such as warm air can be known, and in some cases, normal threshold output (terminal 3
8) is prohibited and safe operation can be performed.

Further, an output based on a normal threshold value (terminal 3
8), the presence or absence of the target object may be determined in consideration of the degree of fluctuation P.

Furthermore, in this embodiment, fuzzy inference is used, but other inference methods and calculation methods may be used.

Further, in the above embodiment, the determination is made based on the number of times that there is no object, but the determination may be made based on the number of times that there is an object.

Further, in the above embodiment, the inference is made based on the signals of the past 12 times, but signals of 13 times or more and 11 times or less may be used.

In the above embodiment, an ultrasonic wave is used as a detection wave, but light or the like may be used.

Also, the present invention can be applied to a proximity switch that detects an object based on a change in electrical characteristics (capacitance and inductance) without using a detection wave.

[0039]

According to the first aspect of the present invention, the object detector includes the past n outputs including the current output from the reflected wave determination means.
The number of times of the signal with / without the reflected wave and the output from the past 2n to n + 1 times from the reflected wave determination means
Calculate how many times the signal with (without) the reflected wave is
Calculating the difference between the output of the number-of-times calculating means and the output of the second number-of-times calculating means, and inferring the presence or absence of an object based on the output of the first number-of-times calculating means and the output of the tendency calculating means. I have to. Therefore, accurate detection can be performed even when the output of the reflected wave determination means is unstable due to disturbance. That is, a highly accurate object detector can be provided.

The object detector according to the second aspect is characterized in that it outputs a detection output based on the output of the reflected wave determination means and the output of the inference means. Therefore, more accurate detection can be performed.

The object detector according to claim 3 is characterized in that the output of the inference means is taken out as a diagnostic output. Therefore, the degree of environmental change can be known.

According to a fourth aspect of the present invention, the object detector includes a summing means for summing the magnitudes of the reflected waves received by the wave receiving means for a predetermined number of times, and the inference means considers the output of the summing means. It is characterized in that it makes inferences. Therefore, more accurate detection can be performed.

According to a fifth aspect of the present invention, the object detector includes the number of times a signal having a reflected wave (absent) is present out of the past n outputs including the current output from the output determining means, and Of the past 2n to n + 1 outputs, calculate how many times there is a signal with or without a reflected wave, and calculate the difference between the output of the first number calculation means and the output of the second number calculation means. In addition, the presence / absence of an object is inferred based on the output of the first number calculation means and the output of the tendency calculation means. Therefore, accurate detection can be performed even when the output of the output determination means is unstable due to disturbance. That is, a highly accurate object detector can be provided.

The object detector according to claim 6 is characterized in that it outputs a detection output based on the output of the output determination means and the output of the inference means. Therefore, more accurate detection can be performed.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of an object detector according to an embodiment of the present invention.

FIG. 2 is a block diagram of an ultrasonic detector according to one embodiment of the present invention.

FIG. 3 is a waveform chart for explaining the operation of the ultrasonic detector.

FIG. 4 is a diagram showing an output change with and without an object.

FIG. 5 is a diagram showing a membership function used for fuzzy inference in the ultrasonic detector.

[Explanation of symbols]

 2 ... Transmission means 4 ... Object 6 ... Reception means 8 ... Reflected wave measurement means 10 ... First number calculation means 12 ... Second number calculation means 14. ..Trend calculation means 16 ... Inference means

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) G01V 1/00

Claims (6)

(57) [Claims] 1. A wave transmitting means for emitting a detection wave toward an object, a wave receiving means for receiving a detection wave transmitted from the wave transmitting means and reflected on the object, and measuring a size of the detection wave received by the wave receiving means. If the threshold value is exceeded, a signal with a reflected wave is output, and if less than the threshold, a signal without a reflected wave is output. First number calculation means for calculating how many times a signal with a reflected wave or a signal without a reflected wave is present among the outputs of the past n times, out of the past 2n to n + 1 times outputs from the reflected wave determination means A second count calculating means for calculating how many times a signal having a reflected wave or a signal having no reflected wave has occurred; and a tendency to calculate the difference between the output of the first count calculating means and the output of the second count calculating means. Calculating means, the output of the first number calculating means and the inclination Based on the output of the arithmetic unit, the object detector with inference means for inferring the degree of environmental changes. 2. The object detector according to claim 1, wherein a detection output is output based on an output of the reflected wave determination means and an output of the inference means. 3. The object detector according to claim 1, wherein an output of the inference means is extracted as a diagnostic output. 4. The object detector according to claim 1, further comprising summing means for summing the magnitudes of the reflected waves received by the wave receiving means for a predetermined number of times, and the inference means also providing an output of the summing means. It is characterized by making inferences with consideration. 5. A detection circuit for detecting a change in electrical characteristics due to the presence or absence of an object. If the magnitude of an output from the detection circuit exceeds a threshold value, a signal with an output is output, and a signal having an output is output. In the case of (1), output determination means for outputting a no-output signal, and among the past n outputs including the current output from the output determination means, calculate how many times a signal with an output or a signal without an output has occurred. A first count calculating means, a second count calculating means for calculating how many times a signal having an output or a signal having no output has been output from the last 2n to n + 1 outputs from the output determining means, Tendency calculating means for calculating the difference between the output of the calculating means and the output of the second number calculating means; inference for inferring the presence or absence of an object based on the output of the first number calculating means and the output of the tendency calculating means; Means, an object detector. 6. The object detector according to claim 5, wherein a detection output is output based on an output of the output determination means and an output of the inference means.