JPH1097685A - Invading object detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an invading object detector which can detect any invading object with a less possibility of erroneous detection even when environmental changes occur and with high sensitivity when the environment changes are less by intermittently transmitting and receiving ultrasonic waves. SOLUTION: An invading object detector discriminates the presence of an invading object when the difference between received data and reference data is larger than an error range and a threshold by comparing the received data with the reference data by means of discriminating means 13-16. The detector calculates the error (for example, the standard deviation) of the received data from a plurality of received data successively selected out of the past received data (the data received when no invader exists) stored in a storing means (storage device 18) from the latest data by means of an error calculating means (error range estimating device 20) and updates the error as the error range. The detector is constituted so that the detector can repeat the updating operations whenever the detector discriminates that at least no invader exists.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intruding object detecting device suitable for, for example, an anti-theft device for a car, and more particularly, to an ultrasonic wave detecting device for detecting the intrusion of a suspicious person or the like into a detecting space (for example, a vehicle). The present invention relates to an intruding object detection device that detects an object.

[0002]

2. Description of the Related Art Conventionally, as this kind of intruding object detecting device, an ultrasonic transmitter / receiver provided at a position such as a ceiling in a vehicle continuously transmits and receives ultrasonic waves,
It is known that an intruding object is detected by using the Doppler effect that the frequency of the reflected wave changes when it hits and reflects on an object (intruding object) moving in the vehicle, and an alarm such as sounding a horn is executed. I have.

However, such a Doppler system has a problem in that transmission and reception of ultrasonic waves must be performed continuously, and power consumption increases. In particular, in the case of preventing theft of a car, the battery runs out for a short period of time because the vehicle is driven with the engine stopped. There is also a drawback that the life of the ultrasonic transducer for transmitting and receiving ultrasonic waves is shortened.

Accordingly, the applicant has filed, for example, Japanese Patent Application No. 4-201.
No. 184 (JP-A-6-52449), an ultrasonic wave is intermittently transmitted to a detection space, a reflected wave is received for a certain period after the transmission, and the received data is used as reference data (for example, previous received data). A device that compares and determines the presence or absence of an intruding object is proposed. This device is excellent in that power consumption can be reduced and the life of the ultrasonic vibrator can be extended because transmission and reception of ultrasonic waves need only be performed intermittently. Further, when the previously received data is updated and used as reference data every time, there is an advantage that a reliable detection operation can be performed without being adversely affected by a change in a reflected wave due to a gradual temperature change in the detection space.

[0005]

However, the apparatus proposed by the applicant in Japanese Patent Application No. Hei 4-201184 described above is:
There were the following problems to be improved in terms of detection accuracy. (1) First, when there is an environmental change such as air fluctuation in the detection space, the received data differs from the reference data by that much even if there is no actual intruding object. There is a high possibility of erroneous detection, in which an intruding object is not actually detected but is determined to be detected. In order to reliably prevent such erroneous detection, the detection sensitivity has to be set lower by an amount such as air fluctuations, for example, by setting a large threshold value for determining the difference from the reference data as abnormal. Not get. For this reason, in this case, even in a state where there is no actual air fluctuation in the detection space, the detection sensitivity is always low, and conversely, an operation that an intruding object cannot be detected is likely to occur. . Note that such a problem also occurs in the case of a conventional Doppler effect type device.

(2) When the previously received data is updated and used as reference data each time, when an intruding object is detected and once detected, the received data of the reflected wave is compared with the next reference data. Therefore, in the next determination process, it is determined that there is no intruding object even if there is an intruding object continuously. Further, in this case, when the intruding object has come out of the detection space in the next determination processing, there is a possibility that an operation of determining that there is an intruding object on the contrary may occur.

Accordingly, the present invention relates to an intruding object detecting apparatus for detecting an intruding object by intermittently transmitting and receiving ultrasonic waves, and has a low possibility of erroneous detection due to an environmental change. It is an object of the present invention to provide an intruding object detection device capable of performing high-sensitivity detection and having no operation after detecting an intruding object.

[0008]

In order to achieve the above object, an intruding object detecting apparatus according to the present invention comprises a transmitting means for intermittently transmitting an ultrasonic wave to a detection space, and a transmitting means for transmitting the ultrasonic wave for a predetermined period after the transmitting means. Receiving means for receiving a reflected wave and outputting received data corresponding to the reflected wave; comparing received data output from the receiving means with reference data; a difference between the received data exceeds an error range and exceeds the error range; Determining means for determining that there is an intruding object when the amount exceeds the threshold value; storing means for storing received data when the determining means determines that there is no intruding object; The operation of calculating the error of the received data from the plurality of received data sequentially selected from the latest received data among the past received data, and updating and setting this error as the error range, at least. An error calculating unit that performs every time it is determined that there is no intruding object; and a newest one of past received data stored in the storage unit or a plurality of received data selected in order from the latest one. Reference data calculation means for calculating data serving as a reference for object detection determination and updating and setting the data as the reference data at least every time it is determined that there is no intruding object. And

[0009]

Embodiments of the present invention will be described below with reference to the drawings. First Example First, a first example which is an example of a case where the device of the present invention is realized by a combination of various arithmetic circuits and the like will be described. FIG.
1 is a block diagram illustrating a configuration of an intruding object detection device according to a first example of the present invention. This apparatus includes an ultrasonic transmitter 1 (transmitting means), an ultrasonic receiver 2 (receiving means), an intermittent driving timer 3, and an ultrasonic wave at a predetermined cycle based on a timing signal output from the intermittent driving timer 3. The control unit 10 drives the transmitter 1 and executes various processes for detecting and determining an intruder from the output of the ultrasonic receiver 2.

Here, the ultrasonic transmitter 1 has an ultrasonic vibrator which is installed, for example, in the ceiling of the vehicle or near the rearview mirror and transmits ultrasonic waves to the inside of the vehicle as a detection space. The ultrasonic receiver 2 also has an ultrasonic vibrator that is installed, for example, in the vicinity of a ceiling or a room mirror in a vehicle and receives a reflected wave. Note that the transmitter 1 and the receiver 2 may be disposed as an integrated product or may be disposed separately.

As shown in FIG. 1, the control unit 10 includes an oscillator 11 (transmitting means), a sampling device 12 (receiving means), a subtractor 13 (determining means), an absolute value calculator 14 (determining means),
Change amount determiner 15 (determination means), determiner 16 (determination means), switch 17, storage device 18 (storage means), reference value calculator 19 (reference data calculation means), and error range estimator 20 (error calculation Means).

Here, the oscillator 11 is a circuit for supplying high-frequency power for driving the ultrasonic vibrator of the ultrasonic transmitter 1, and based on a timing signal of the intermittent driving timer 3, for example, FIG. As shown in (1), the ultrasonic transmitter 1 is driven at the time interval of the period T2 for the period T1, and the ultrasonic waves are intermittently transmitted to the detection space. After the transmission is completed (period T
During a period T3 (T3 <T2−T1) from the end of (1), the received wave received by the ultrasonic receiver 2 is read and sampled every time. Here, the sampling is a process of amplifying a received wave as necessary, further detecting the converted wave, and converting it into predetermined received data. For example, the detected wave is integrated, and the coordinates of the area and the center of gravity are calculated. Is output as reception data. More specifically, for example, the area of the detection output and the coordinates of the center of gravity as shown in FIG.

The subtractor 13 is a computing unit that subtracts the reference data output from the reference value calculator 19 from the received data output from the sampling device 12, and outputs the difference between them. The absolute value calculator 14 is a calculator that converts the output of the subtractor 13 into an absolute value. The change amount determiner 15 outputs, as a change amount, an absolute value output from the absolute value calculator 14 that exceeds the error range output from the error range estimator 20. The determiner 16 is a change amount determiner 1
A circuit that determines whether the amount of change output from 5 exceeds a threshold value, turns the output on ("1") if the change amount exceeds the threshold value, and turns off the output ("0") otherwise. It is.

The switch 17 operates when the output of the decision unit 16 is on, and cuts off the input of the received data output from the sampling device 12 to the storage device 18.
The storage device 18 determines that there is no intruding object by the operation of the switch 17 (when the output of the determiner 16 is off).
Is a memory for storing the received data output from the sampling device 12. In the received data stored in the storage device 18, the reference value calculator 19 or the error range estimator 2
It is preferable that the old past received data that is no longer used in the processing described below in 0 is appropriately deleted.

The reference value calculator 19 serves as a reference for intruding object detection determination from the latest received data stored in the storage device 18 or a plurality of received data sequentially selected from the latest data. This is an arithmetic unit that performs an operation of calculating data and updating and setting this data as reference data to be output to the subtractor 13 at least whenever it is determined that there is no intruding object. Specifically, for example, the storage device 1
8 to output the latest received data as the reference data each time,
The average of a plurality of pieces of received data selected in order from the latest received data among the past received data stored in 8 is calculated every time,
This average is output as the reference data.

The error range estimator 20 includes a storage device 18
, An error of the received data is calculated from a plurality of received data sequentially selected from the latest received data among the past received data, and the error is updated and set as an error range to be output to the change amount determiner 15. This is a computing unit that performs an operation at least every time it is determined that there is no intruding object.
Specifically, for example, the standard deviation of the plurality of received data,
Alternatively, the average (absolute average error) of the absolute value of the deviation with respect to the average value of the plurality of received data is obtained each time, and the standard deviation or the absolute average error is output as an error range.

The apparatus configured as described above detects an intruding object as follows, responds to changes in the environment such as air fluctuations in the detection space, and prevents operation after detecting intrusion. Is realized. First, when there is almost no change in the environment in a short time such as air fluctuation, unless there is an intruding object, the received data output every time ultrasonic waves are transmitted and received from the sampling device 12 are substantially equal data. Will be continuous. Therefore, the received data groups stored in the storage device 18 every time become almost equal data, and the reference data output from the reference value calculator 19 become almost equal to these data. Even if there is a gradual environmental change such as a temperature change, and the received data gradually changes in response to this, the received data that is the basis of the reference data is always the latest or the latest as described above. Are used, the received data output from the sampling device 12 also has almost the same value as the reference data output from the reference value calculator 19 every time. Therefore, in this case, unless there is an intruding object, the output of the subtractor 13 (the difference between the latest received data and the latest reference data) input to the absolute value calculator 14 becomes almost zero, and the The output will definitely turn off.

Further, in this case, the error range (for example, standard deviation) calculated by the error range estimator 20 is always equal to or close to zero because the data is almost equal unless there is an intruding object. And the output is almost the same. For this reason, when an intruding object is generated in this state and the reception wave changes, and the reception data output from the sampling device 12 changes accordingly, the absolute value of the change is directly used by the change amount determination unit 15. When the amount of change exceeds the threshold, the output of the determiner 16 is turned on, and an intruding object is detected and determined. Therefore, when there is little change in the environment in a short time or when there is little change, the error range used in the change amount determiner 15 becomes almost zero or a small value, and the substantial sensitivity is obtained. And the detection determination of the intruding object is executed with higher reliability.

Next, in a state where the environment fluctuates in a short time such as air fluctuation, even if there is no intruding object, the reception data output every time the ultrasonic wave is transmitted and received from the sampling device 12 is And the output of the subtractor 13 has a larger value. However, in this case, the received data group stored in the storage device 18 every time is data in which the corresponding value varies, so that the error range calculated by the error range estimator 20 becomes a correspondingly large value. , The output of the change amount determiner becomes smaller than the input. Therefore, in the case where the fluctuation of the environment is large, the substantial sensitivity is reduced correspondingly, and the erroneous detection that the output of the determiner 16 is turned on even when there is no intruding object is reliably avoided. . Even in this case, if there is an intruding object and the received data fluctuates beyond the error range, the output of the change amount determining device exceeds the threshold value and the output of the determining device 16 is turned on. An intruding object can be detected with the same level of sensitivity.

In the apparatus of this embodiment, when the output of the determiner 16 is turned on and the detection of the intruding object is determined, the received data at that time is not registered in the storage device by the operation of the switch 17 described above. Are not used as basic data for calculating reference data in the reference value calculator 19 or calculating an error range in the error range estimator 20. For this reason,
An operation of not detecting an intruding object after detecting an intruding object and an operation of determining that an intruding object is present when the intruding object exits the detection space are prevented.

Second Example Next, a second example which is an example of a case where the device of the present invention is realized by a microcomputer will be described. FIG.
FIG. 4 is a block diagram showing a configuration of the intruding object detection device of the second example. As shown in FIG. 2, this apparatus includes a transmitting unit 30 that transmits ultrasonic waves intermittently at time intervals of about 0.5 to 1.0 seconds (T2 shown in FIG. 4), and a fixed time after transmission. (T3 shown in FIG. 4) is provided with a receiving means 40 for receiving a reflected wave and outputting received data corresponding to the reflected wave, and a microcomputer 50 for detecting and determining an intruder based on the received data. . Note that the microcomputer 50 functions as a determination unit, a storage unit, an error calculation unit, and a reference data calculation unit in the present invention.

The transmitting means 30 includes, for example, an ultrasonic vibrator 31 which is installed near the ceiling in the vehicle or near the rearview mirror and transmits ultrasonic waves to the inside of the vehicle, which is a detection space, and the like. The driving circuit 32 is driven in accordance with the above-mentioned command, and intermittently transmits ultrasonic waves at intervals T2 for a period of T1 as shown in FIG.

The receiving means 40 also includes, for example, an ultrasonic vibrator 41 installed near a ceiling or a room mirror in a vehicle for receiving a reflected wave, an amplifying circuit 42 for amplifying the output of the ultrasonic vibrator 41, It has a detection circuit 43 for detecting the output of the amplification circuit 42, and an A / D converter 44 for A / D converting the output of the detection circuit 43 and outputting it as received data. The receiving means 40 includes the transmitting means 30
FIG. 4 shows a certain period T3 after transmission of ultrasonic waves by
4B, the reflected wave is received, amplified by the amplifier circuit 42, detected by the detection circuit 43 as shown in FIG. 4C, and the detected output is output as shown in FIG. 4D. A / D conversion is performed and output to the microcomputer as reception data.
Note that the transmitting means 30 and the receiving means 40 may be arranged as an integrated product or may be separately installed.

The microcomputer 50 stores an operation program shown in the flowchart of FIG.
M51, a RAM 52 as storage means for storing data received from the receiving means 40, and a CPU 53 for performing determination processing of presence / absence of an intruding object and other control processing as described later in accordance with the operation program. .

Next, the operation of the above-described intruding object detection device will be described with reference to the flowchart of FIG. First,
The microcomputer 50 determines whether or not the period T2 in FIG. 4 has elapsed (step S2). When the period has elapsed, the microcomputer 50 operates the transmitting unit 30 to transmit ultrasonic waves over the period T1 in FIG. 4 (step S4). . Next, after the transmission in step S4 is completed, the receiving means 40 is activated to start receiving the reflected wave (step S6), and the A / D converted reception data is read as shown in FIG. 4D (step S8). ), It is determined whether the period T3 in FIG. 4 has elapsed (step S10).

When the period T3 has elapsed, the reception by the receiving means 40 is stopped (step S12), and the current reception data and the reference data (the latest stored reference data, that is, usually the previous reception data). And a difference between them is obtained (step S14), and the presence or absence of an intruding object is determined based on the difference (step S16). This determination is made, for example, by comparing this received data as shown in FIG. 5C with reference data as shown in FIG. 5B, for example, and comparing these differences (for example, as shown in FIG. 5D). ) Is greater than the latest error range set in step S24 described later and exceeds a threshold value.

More specifically, for example, the absolute value of the difference between the area of the figure of the received data and the area of the figure of the reference data is obtained, and this value is calculated as the area of the figure in the error range shown in the lower part of FIG. In the following, it is determined that there is an intruding object when an amount exceeding the area error exceeds a certain threshold value. Alternatively, for example, the absolute value of the distance between the center of gravity of the graphic of the received data and the center of gravity of the graphic of the reference data is obtained, and the reference data when this value varies within an error range as shown in the lower part of FIG. When the amount exceeds the variation amount of the barycentric point coordinates (hereinafter, referred to as the barycentric point error) of the graphic of FIG. Further alternatively, both the determination based on the area of the graphic of each of the data and the determination based on the center of gravity of the graphic of each of the data are performed. It may be determined that there is an object.

Next, when it is determined that there is an intruding object, an intrusion detection signal is output to a warning means such as a horn drive device of the vehicle and the process returns to step S2 (step S18), while it is determined that there is no intruding object. Sometimes, the following reception data processing (step S20), reference data update processing (step S22), error range update processing (step S20)
After performing step 24), the process returns to step S2.

In the reception data processing, the current data read in step S8 is stored as the latest reception data at a predetermined address in the ROM 51 where the past reception data is stored in a plurality of orders, and the previously stored previous data is stored. If old data not used in the subsequent processing is included in the received data, the old data is deleted as necessary. In the reference data update process, reference data to be used in the next process of step S16 is newly determined or calculated and updated and set. As the reference data, for example, the latest received data may be set, or an average of a plurality of pieces of received data selected in order from the latest among the stored received data may be calculated, and the average of the average may be calculated. The data may be updated and set as reference data.

In the error range updating process, as shown in the lower part of FIG. 6, a plurality of pieces of received data selected in order from the latest received data stored in the past as shown in the upper part of FIG. An error of the received data is newly calculated, and this error is updated and set as the error range used in the next process of step S16. As the error, specifically, for example, a standard deviation or the average of the absolute value of the deviation with respect to the average of the plurality of received data (absolute average error) is calculated.

According to the processing of steps S2 to S24, as in the first example, the detection of the intruding object is performed as follows, and the response to the environmental change such as the fluctuation of the air in the detection space can be performed. Thus, prevention of operation after intrusion detection is realized. First,
In the case where there is almost no change in the environment in a short time such as air fluctuation, the received data output from the receiving means 40 every time the ultrasonic wave is transmitted and received (period T2) is almost equal unless there is an intruding object. The data will be continuous. For this reason, in the received data group stored in the ROM 51 every time in the processing in step S20, substantially the same data is continuously present, and the reference data set in step S22 is also substantially the same. Even if there is a gradual environmental change such as a temperature change, and the received data gradually changes in response to this, the received data that is the basis of the reference data is always the latest or the latest as described above. Are used, the receiving means 40
The received data output from each time has a value substantially equal to the reference data set in step S22 every time. Therefore,
In this case, as long as there is no intruding object, the determination result in the determination processing in step S16 is surely no intruding object.

Further, in this case, the error range (for example, standard deviation) calculated and set in step S24 is always equal to or close to zero since the data is almost equal unless there is an intruding object. Therefore, in this state, an intruding object is generated and the received wave changes, and the received data output from the receiving means 40 changes accordingly. If the change exceeds the threshold value, the process of step S16 is performed. , An intruding object is detected and determined. Therefore, when there is almost no change in the environment in a short time or when there is little change, the error range used in the determination processing in step S16 becomes almost zero or a small value, and the substantial sensitivity is reduced. And the detection determination of the intruding object is executed with higher reliability.

Next, in a state where the environment fluctuates in a short time such as air fluctuation, even if there is no intruding object, the receiving means 4
The received data output from 0 changes every time, and the difference between the received data and the reference data becomes a larger value. However, in this case, the received data group stored in the ROM 51 every time is data in which the value varies, so that the error range calculated in the error range updating process in step S24 has a larger value. Even if the difference between the received data and the reference data is large, the amount exceeding the error range hardly reaches a value exceeding a certain threshold value. Therefore, when the environmental fluctuation is large, the substantial sensitivity is reduced by that much, and erroneous detection in which it is determined that there is an intruding object in the processing in step S16 even though there is no intruding object is reliably avoided. Is done. Even in this case, if there is an intruding object and there is a change in the received data exceeding the above-mentioned error range, step S1 is executed.
In the process of 6, since the amount exceeding the error range exceeds the threshold value and it is determined that there is an intruding object, it is possible to detect the intruding object with at least the same sensitivity as in the related art.

In the apparatus of this embodiment, when the detection of the intruding object is determined in the process of step S16, the process proceeds to step S16.
, The processing of steps S20 to S24 is not executed, and the received data at that time is not used as basic data for calculating reference data or calculating an error range. Therefore, an operation of not detecting an intruding object after detecting an intruding object or an operation of determining that an intruding object is present when the intruding object exits the detection space is prevented.

[0035]

According to the intruding object detecting device of the present invention, the transmitting means transmits the ultrasonic waves to the detection space intermittently.
The reflected wave is received by the receiving means for a certain period after the transmission, and the detection means determines and detects the intruding object based on the received data, so that the power consumption is significantly lower than that of the conventional Doppler system. And the life of the ultrasonic transducer for transmitting and receiving ultrasonic waves is shortened.

Further, in the present apparatus, the received data and the reference data are compared by the judging means, and it is judged that an intruding object is present when the difference between the received data and the reference data exceeds the error range and the amount of the difference exceeds the threshold value. . And the error calculating means is:
An error (for example, a standard deviation) of the received data is calculated from a plurality of received data sequentially selected from the latest received data among the past received data stored in the storage means, and the error is updated and set as the error range. Is performed each time at least it is determined that there is no intruding object. The reference data calculating means calculates data serving as a reference for intruding object detection determination from the latest received data stored in the storage means or a plurality of received data sequentially selected from the latest data. Then, an operation of updating and setting this data as the reference data is performed every time at least it is determined that there is no intruding object.

For this reason, when there is a short-term environmental change such as air fluctuation, the substantial sensitivity is reduced as before, and erroneous detection is prevented with high reliability. When the fluctuation of the environment with time is small, the substantial sensitivity is higher than before, and an intruding object can be detected more reliably than before. In addition, even if there is a gradual environmental change such as a temperature change, erroneous detection is not performed, and highly reliable detection of an intruding object is realized with the highest sensitivity according to the situation.

That is, first, when there is almost no change in the environment in a short time such as air fluctuation, unless there is an intruding object, the received data output from the receiving means every time is:
Approximately equal data will be continuous. For this reason, in the received data group stored in the storage means, substantially the same data is continuous, and the reference data set by the reference data calculation means is also substantially the same. Due to gradual environmental changes such as temperature changes,
Even if the received data changes gradually in response to this, the latest received data or a plurality of data close to the latest is used as the received data serving as the basis of the reference data as described above. The received data has almost the same value each time as the reference data set by the reference data calculation means. Therefore, in this case, as long as there is no intruding object, the judgment result of the judging means will surely be no intruding object.

Further, in this case, the error range (for example, the standard deviation) calculated and set by the error calculating means always becomes zero or a value close to zero because the data is almost equal unless there is an intruding object. Therefore, when an intruding object is generated in this state and the received wave changes, and the received data output from the receiving means changes accordingly, if the change exceeds the threshold, the processing by the determining means is performed. An intruding object is detected and determined. Therefore, when there is almost no change in the environment in a short time or when there is little change, the error range used by the determination means is almost zero or a small value, and the substantial sensitivity is correspondingly reduced. As a result, the detection determination of the intruding object is performed more reliably and reliably.

In this apparatus, when the detection of the intruding object is determined, the received data at that time is not stored in the storage means as at least the reference data or the basic data for updating the error range. Not used as. For this reason, it is possible to prevent an operation of not detecting an intruding object after detecting an intruding object, or a conventional operation of determining that an intruding object is present when the intruding object exits the detection space. It also has an effect.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first example of an intruding object detection device.

FIG. 2 is a block diagram illustrating a second example of the intruding object detection device.

FIG. 3 is a flowchart illustrating an operation of a second example of the intruding object detection device.

FIG. 4 is a diagram illustrating an example of a transmission wave, a reception wave, and reception data.

FIG. 5 is a diagram illustrating an example of received data, reference data, and a difference therebetween.

FIG. 6 is a diagram illustrating a method of calculating an error range.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 ultrasonic transmitter (transmitting means) 2 ultrasonic receiver (receiving means) 11 oscillator (transmitting means) 12 sampling device (receiving means) 13 subtractor (determining means) 14 absolute value calculator (determining means) 15 change Quantity determiner 15 (determination means) 16 determiner (determination means) 17 switch (storage means) 18 storage device (storage means) 19 reference value calculator 19 (reference data calculation means) 20 error range estimator 20 (error calculation means) 30) transmitting means 40 receiving means 50 microcomputer 53 CPU (determining means, error calculating means, reference data calculating means) 51 RAM (storage means)

Claims (1)

[Claims] 1. A transmitting means for intermittently transmitting an ultrasonic wave to a detection space, and a receiving means for receiving a reflected wave for a predetermined period after transmission by the transmitting means and outputting received data corresponding to the reflected wave. Comparing the received data output from the receiving means with the reference data, and determining that there is an intruding object when the difference exceeds the error range and the amount of the difference exceeds a threshold. A storage unit for storing received data when it is determined that there is no intruding object by the determining unit; and a plurality of received data sequentially selected from the latest received data among past received data stored in the storage unit. An error calculating unit that calculates an error of the received data and updates and sets the error as the error range at least when it is determined that there is no intruding object; and From the stored past received data, the latest data, or a plurality of received data sequentially selected from the latest data, calculate data serving as a reference for intruding object detection determination, and update this data as the reference data. An intruding object detection device comprising: a reference data calculating unit that performs an operation of setting at least every time it is determined that there is no intruding object.