INTRUSION DETECTION SYSTEM

Abstract

In the intrusion detection system for detecting objects entering a predefined area, the detection of objects allowed into the area is appropriately disabled. The intrusion detection system (10) for detecting objects (B) entering area (E2) includes: an intrusion detection sensor (5) configured to detect whether a part of object (B) is present in the intrusion detection plane (P); a mute sensor part (3) consisting of the first device (1) and the second device (2); and a control device (7).The control device (7) disables the intrusion detection sensor (5) in response to at least one of the first detection state (ST1) and the second detection state (ST2) being set, the first detection state (ST1) being the state in which the first device (1) positioned in the direction of passage - the first side (Y1) of the intrusion detection plane (P) detects the object (B) and the second detection state (ST2) being the state in which the second device (2) positioned in the direction of passage - the second side (Y2) of the intrusion detection plane (P) detects the object (B).

Description

ENTRY DETECTION SYSTEM

[0001] The present invention relates to an intrusion detection system that detects an object entering a predefined area.

[0002] Japanese Patent Application Laid-Open Publication No. 2010-133503 discloses a safety system that includes a light curtain (30) at a loading entrance through which an item (31) is carried into a specific area, and that detects when a worker or the like enters the specific area through the loading entrance (reference numerals in parentheses in the Background Art section are those of the referenced document). Since the light curtain (30) also detects the item (31) to be carried in, it is provided with a function (muting function) that disables the detection by the light curtain (30) when the item (31) is being carried in. Specifically, two sets of retroreflective photoelectric sensors are installed as muting sensors with detection ranges that intersect near the detection surface of the light curtain (30) in a plan view. When the item (31) to be carried in is detected in front of the loading entrance along the loading path, the detection by the light curtain (30) is disabled.

[0003] JP 2010-133503 A

[0004] In the above-described system, the detection ranges of the two sets of retro-reflective photoelectric sensors intersect, and therefore unless the angle of intersection between them is large, it is not possible to ensure a large distance from the detection surface of the light curtain to the object detection position. However, in order to increase the angle of intersection, a large installation space is required to place the two sets of retro-reflective photoelectric sensors away from the light curtain. Furthermore, when the installation space is limited, it is not possible to ensure a sufficient distance between the detection position of the muting sensor and the detection position of the light curtain, and depending on the shape of the object, it may not be possible to properly disable the light curtain.

[0005] In view of the above background, it is desirable to provide a technology that can appropriately disable the detection of an object whose entry is permitted in an intrusion detection system that detects an object entering a predefined area.

[0006] In view of the above, an intrusion detection system that detects an object entering a predetermined area includes an intrusion detection sensor that detects whether or not a part of the object is present on an intrusion detection surface that is set in a planar shape of a predetermined range, a muting sensor that detects the object to invalidate the detection of the object by the intrusion detection sensor, the muting sensor having a first unit and a second unit, and a control unit that controls operation of the intrusion detection sensor based on the detection result of the muting sensor, wherein a direction perpendicular to the intrusion detection surface is defined as a passing direction, one side of the passing direction is defined as a first passing direction side, and the other side is defined as a second passing direction side, and the first unit includes a pair of first sensors that are arranged opposite to and spaced apart in a width direction that is a direction parallel to the intrusion detection surface on the first passing direction side, and each of the pair of first sensors detects whether or not the object is present within a predetermined first detection range, and the first detection range is defined as a pair of first sensors. a pair of first sensors extend in opposing directions in the width direction from each of the first sensors, and the pair of first detection ranges are set to be spaced apart from each other in the width direction; the second unit has a pair of second sensors arranged opposite each other and spaced apart in the width direction on the second side of the passing direction from the entry detection surface, and each of the pair of second sensors detects whether the object is present within a predetermined second detection range, and the second detection range extends from each of the pair of second sensors in a direction in which the pair of second sensors face each other in the width direction, and the pair of second detection ranges are set to be spaced apart from each other in the width direction; and the control unit disables the entry detection sensor when at least one of a first detection state in which both of the pair of first sensors detect the object and a second detection state in which both of the pair of second sensors detect the object is established.

[0007] According to this configuration, muting sensors capable of detecting objects are installed on both the first and second sides of the intrusion detection surface in the passing direction. Therefore, an object approaching the intrusion detection surface along the passing direction can be detected by one of the muting sensors on the first and second sides before the object reaches the intrusion detection surface. Furthermore, if the entire object has passed through the detection range of the muting sensor on one side, and a portion of the object still remains on the intrusion detection surface, the object can be detected by the muting sensor on the other side. Therefore, if the detected object is permitted to pass through the intrusion detection surface, the intrusion detection sensor can be quickly disabled before the object reaches the intrusion detection surface, and the intrusion detection sensor can be appropriately disabled until the object passes the intrusion detection surface. Furthermore, according to this configuration, the first sensor constituting the muting sensor is disposed on the first side of the intrusion detection surface in the passing direction, and the second sensor is disposed on the second side of the intrusion detection surface in the passing direction. That is, the detection ranges of the first and second sensors do not intersect, but are parallel to the intrusion detection surface. Therefore, even in a relatively small installation space, it is easy to appropriately set the positional relationship between the detection position of the muting sensor and the detection position of the intrusion detection sensor along the passage direction. Furthermore, by setting a pair of first detection ranges to be spaced apart from each other in the width direction and a pair of second detection ranges to be spaced apart from each other in the width direction, the intrusion detection sensor is not disabled unless both of the pair of first sensors detect an object or both of the pair of second sensors detect an object. Therefore, the intrusion detection sensor can be enabled for objects that do not fall within both of the pair of first detection ranges and both of the pair of second detection ranges. Therefore, the intrusion detection sensor can appropriately detect the passage of objects whose entry is not permitted. Thus, this configuration provides a technology that can appropriately disable the detection of objects whose entry is permitted in an intrusion detection system that detects objects entering a predetermined area.

[0008] Further features and advantages of the intrusion detection system will become apparent from the following description of exemplary, non-limiting embodiments that refer to the drawings.

[0009] FIG. 1 is a diagram showing an example of an article conveying facility equipped with an intrusion detection system; FIG. 2 is a block diagram showing an example of the configuration of an intrusion detection system; FIG. 3 is an explanatory diagram showing an example of the detection range of an intrusion detection system; FIG. 4 is a diagram showing an example of the detection range of a muting sensor in the width direction; FIG. 5 is a diagram showing an example of the arrangement position of the intrusion detection system along the passing direction;

[0010] An embodiment of an intrusion detection system will be described below with reference to the drawings. The intrusion detection system is installed in a facility (e.g., an article conveying facility or a production facility) that has a specific controlled area where access by workers and other personnel is restricted, and a general area where restrictions are less stringent than the controlled area. FIG. 1 schematically shows an example of such a facility (here, a conveying facility 100). FIG. 2 is a block diagram showing an example of the configuration of the intrusion detection system installed in the conveying facility 100. FIG. 3 shows an example of the detection range of the intrusion detection system.

[0011] The conveyance equipment 100 conveys items along a predetermined route R. The route R may be a tracked route formed by rails or the like, or may be a trackless route that does not have rails or the like and is set, for example, based on coordinates on a floor surface. The items are conveyed by an item transport vehicle (an example of object B). For example, when the route R is trackless, an AGV (Automatic Guided Vehicle) is used as the item transport vehicle.

[0012] The conveying facility 100 includes at least a general area E1 and a management area E2. For example, the management area E2 includes a warehouse for storing items and production facilities for producing items. For example, the warehouse includes an automatic transfer machine for transferring items between the warehouse and an item transport vehicle, and the production facility includes an automatic machine tool. Therefore, access to the management area E2 is generally restricted, including for workers. If a person accidentally enters the management area E2, it is preferable to stop the operation of the automatic transfer machine, automatic machine tool, etc. for safety reasons. Therefore, the conveying facility 100 includes an intrusion detection system 10 that detects an object B entering the management area E2, which is a predefined area. The management area control unit 9 shown in FIG. 2 can stop the operation of the automatic transfer machine, automatic machine tool, etc. within the management area E2 based on the detection results of the intrusion detection system 10 (particularly, the intrusion detection sensor 5 described below).

[0013] As shown in FIG. 2 , the intrusion detection system 10 includes an intrusion detection sensor 5 that detects an object B, a muting sensor 3 that detects the object B to disable the detection of the object B by the intrusion detection sensor 5, and a control unit 7 that controls the operation of the intrusion detection sensor 5 based on the detection result of the muting sensor 3. As shown in FIG. 1 , the intrusion detection sensor 5 detects whether or not a portion of the object B is present on an intrusion detection plane P that is set as a flat plane within a specified range. In this embodiment, the intrusion detection plane P is set perpendicular to the route R. Here, the direction perpendicular to the intrusion detection plane P is defined as the passing direction Y, and one side of the passing direction Y is defined as a passing direction first side Y1, and the other side is defined as a passing direction second side Y2. Furthermore, one direction perpendicular to the passing direction Y and parallel to the intrusion detection plane P is defined as a width direction X. In this embodiment, of the directions perpendicular to the passing direction Y, the direction along a horizontal plane is defined as the width direction X.

[0014] In this embodiment, the intrusion detection sensor 5 is an optical sensor called a light curtain. The intrusion detection sensor 5 is configured by a light emitter 51 (see FIG. 3 , etc.) having a plurality of light-emitting elements arranged in a row, and a light receiver 52 (see FIG. 3 ) having the same number of light-receiving elements arranged in a row, which are arranged opposite each other in the width direction X. An intrusion detection plane P is formed by light irradiated from the light emitter 51 to the light receiver 52. When an object B blocks the light irradiated from the light emitter 51 to the light receiver 52, the intrusion detection sensor 5 detects that a part of the object B is present on the intrusion detection plane P.

[0015] As shown in FIGS. 2 and 3 , the muting sensor 3 includes a first unit 1 and a second unit 2. The first unit 1 includes a pair of first sensors S1 (S1a, S1b) arranged opposite to each other and spaced apart in the width direction X on a first side Y1 in the passing direction relative to the intrusion detection plane P. The second unit 2 includes a pair of second sensors S2 (S2a, S2b) arranged opposite to each other and spaced apart in the width direction X on a second side Y2 in the passing direction relative to the intrusion detection plane P. As shown in FIGS. 1 and 3 , each of the pair of first sensors S1 (S1a, S1b) detects whether an object B is present within a predetermined first detection range K1. Similarly, each of the pair of second sensors S2 (S2a, S2b) detects whether an object B is present within a predetermined second detection range K2.

[0016] As shown in FIGS. 1 and 3 , the first detection range K1 extends from each of the pair of first sensors S1 (S1a, S1b) in a direction in which the pair of first sensors S1 (S1a, S1b) face each other in the width direction X. The first detection range K1 is set so that the pair of first detection ranges K1 are spaced apart from each other in the width direction X. Similarly, the second detection range K2 extends from each of the pair of second sensors S2 (S2a, S2b) in a direction in which the pair of second sensors S2 (S2a, S2b) face each other in the width direction X. The second detection range K2 is set so that the pair of second detection ranges K2 are spaced apart from each other in the width direction X.

[0017] The muting sensor 3 is configured by a sensor that detects the presence or absence of an object within a set distance range. The first unit 1 detects whether or not an object B is present within a first detection range K1 in opposing directions in the width direction X, using each of the pair of first sensors S1 (S1a, S2b). Alternatively, the first unit 1 may be configured by a distance sensor that detects the distance from each of the pair of first sensors S1 (S1a, S2b) to the object B when the object B is present within the first detection range K1. The same applies to the second unit 2. In this embodiment, an ultrasonic sensor is used as the muting sensor 3. The intrusion detection sensor 5 is an optical sensor as described above. By differentiating the detection principles of the intrusion detection sensor 5 and the muting sensor 3, interference between them is eliminated, and a decrease in detection accuracy and erroneous detection are suppressed.

[0018] 6, a state in which both of the pair of first sensors S1 (S1a, S1b) detect object B, i.e., a state in which the first unit 1 detects object B, is referred to as a first detection state ST1. Also, a state in which both of the pair of second sensors S2 (S2a, S2b) detect object B, i.e., a state in which the second unit 2 detects object B, is referred to as a second detection state ST2. Also, a state in which the intrusion detection sensor 5 detects object B is referred to as an intrusion detection state STW.

[0019] When at least one of the first detection state ST1 and the second detection state ST2 is established, the control unit 7 disables the intrusion detection sensor 5. Here, the disablement may be a form in which the intrusion detection sensor 5 is controlled so that it does not detect the object B, for example, so that it does not enter the intrusion detection state STW, or a form in which even if the intrusion detection sensor 5 detects the object B and enters the intrusion detection state STW, the control unit 7 or the management area control unit 9 (see FIG. 3 ) ignores the detection state.

[0020] 6 , at time t1, when the first unit 1 detects object B, the first detection state ST1 is entered and the control unit 7 disables the entry detection sensor 5. Even if the entry detection sensor 5 subsequently detects object B at time t2 and enters the entry detection state STW, the entry detection sensor 5 remains disabled because the first detection state ST1 is established. At time t3, the second unit 2 also detects object B and enters the second detection state ST2. At time t4, object B passes the first sensor S1 and the first detection state ST1 is canceled, but the second detection state ST2 is established and the entry detection sensor 5 continues to be disabled.

[0021] At time t5, object B passes over the entry detection surface P, and the entry detection state STW is also canceled. At a subsequent time t6, object B also passes over the second sensor S2, and the second detection state ST2 is also canceled, and the entry detection sensor 5 is enabled. In this case, the period from time t1 to time t6, during which at least one of the first detection state ST1 and the second detection state ST2 is established, becomes a mute period M (first mute period M1), and the entry detection sensor 5 is disabled. It is preferable that there be a period during which the first detection state ST1 and the second detection state ST2 overlap, such as from time t3 to time t4, so that the disabling continues without interruption while object B passes over the entry detection surface P.

[0022] Note that after the intrusion detection sensor 5 no longer detects object B, that is, after time t5, object B will not be detected even if the intrusion detection sensor 5 is not disabled. If the time from time t5 to time t6 is long, there is a possibility that object B (e.g., a person) whose entry should be restricted may enter the management area E2 by following a target object TB (see FIG. 4, etc.) that is permitted to enter the management area E2. In this embodiment, it is possible to easily make different the first passing direction separation distance F1 (see FIG. 5), which is the separation distance between the position of the first detection range K1 in the passing direction Y and the intrusion detection surface P, and the second passing direction separation distance F2 (see FIG. 5), which is the separation distance between the position of the second detection range K2 in the passing direction Y and the intrusion detection surface P.

[0023] For example, the first passing direction separation distance F1 is preferably set to a length that ensures sufficient time between the detection of the target object TB and the deactivation of the entry detection sensor 5. Specifically, the position of the first detection range K1 in the passing direction Y is preferably set based on the sum of the time required for detection by the first sensor S1 and the time required from detection to deactivation, and the moving speed of the article transport vehicle serving as the target object TB. The second passing direction separation distance F2 is preferably set based on the sensitivity of the entry detection sensor 5 and the second sensor S2 so that the entry detection sensor 5 is not detecting the target object TB at the time when the second sensor S2 earliest stops detecting the target object TB. Of course, the first passing direction separation distance F1 and the second passing direction separation distance F2 may be the same.

[0024] In addition, when at least one of the first detection state ST1 and the second detection state ST2 is established, the inter-unit separation distance F, which is the separation distance along the passing direction Y between the first unit 1 (first sensor S1) and the second unit 2 (second sensor S2), is set to be shorter than the length along the passing direction Y of the target object TB so that the entry detection sensor 5 is disabled.

[0025] As described above, in this embodiment, the muting sensors 3 are installed on both the first passing direction side Y1 and the second passing direction side Y2 of the entry detection surface P. Therefore, an object B approaching the entry detection surface P can be detected by the muting sensor 3 (first unit 1) on one side before the object B reaches the entry detection surface P. Furthermore, after the entire object B has passed through the detection range of the first unit 1, in a state in which at least a portion of the object B is still present on the entry detection surface P, the object B is detected by the muting sensor 3 (second unit 2) on the other side. Therefore, in the case where the object B is a target object TB that is permitted to pass through the entry detection surface P, the entry detection sensor 5 can be appropriately disabled, and the target object TB can pass through the entry detection surface P.

[0026] Furthermore, the first unit 1 and the second unit 2 are arranged so that their detection ranges are parallel to the entry detection plane P. Therefore, as described above, it is easy to appropriately set the positional relationship along the passing direction Y between the detection position of the muting sensor 3 and the detection position of the entry detection sensor 5. This ensures a sufficient amount of time from when the muting sensor detects an object TB whose entry is permitted until the entry detection sensor 5 is disabled, and also makes it possible to appropriately set the time until the disabling of the entry detection sensor 5 is completed.

[0027] The muting sensor 3 must detect target objects TB, which are objects B that are permitted to pass through the entry detection surface P, but must not detect objects B that restrict the passage of people or other objects. Therefore, the first separation distance D1 (see FIG. 3 ), which is the separation distance in the width direction X between a pair of first detection ranges K1, and the second separation distance D2 (see FIG. 3 ), which is the separation distance in the width direction X between a pair of second detection ranges K2, must be appropriately set. Because the target objects TB of the first unit 1 and the second unit 2 are the same, the first separation distance D1 and the second separation distance D2 may be the same value. For example, the first separation distance D1 and the second separation distance D2 are preferably set based on the target object width H, which is the length in the width direction X of the target object TB that is permitted to pass through the entry detection surface P. The target object width H is not limited to the width of the article transport vehicle. In cases where the article being transported exceeds the width of the article transport vehicle and is transported with the article protruding in the width direction X, the width of the article to be transported may be used as the target object width H.

[0028] Incidentally, errors may occur when an article transport vehicle or the like travels along the route R. In particular, positional deviation may occur in the width direction X. Therefore, as shown in Fig. 4, it is preferable that the first separation distance D1 and the second separation distance D2 be set based on an allowable deviation width G, which is a range within which positional deviation is allowable in the width direction X when the target object TB moves along the passing direction Y.

[0029] For example, if the target object TB is shifted by a first allowable deviation width G1 toward the first width direction side X1, which is one side in the width direction X, the detection range of one of the pair of first sensors S1 (the same applies to the second sensor S2) S1b (the same applies to the second sensor S2) must be extended by "G1" toward the first width direction side X1. Similarly, if the target object TB is shifted by a second allowable deviation width G2 toward the second width direction side X2, which is the other side in the width direction X, the detection range of the other of the pair of first sensors S1 (the same applies to the second sensor S2) S1a (the same applies to the second sensor S2) must be extended by "G2" toward the second width direction side X2. In other words, the detection range K is extended in the direction in which the pair of first sensors S1 (the same applies to the second sensor S2) face each other by the allowable deviation width G, which is the sum of the first allowable deviation width G1 and the second allowable deviation width G2. Therefore, it is preferable that the first separation distance D1 and the second separation distance D2 are set based on the allowable deviation width G as well.

[0030] That is, the widthwise separation distance D (first separation distance D1 and second separation distance D2) is set based on the target object width H and the allowable deviation width G. Specifically, as shown in FIG. 4 , the widthwise separation distance D (first separation distance D1 and second separation distance D2) is set to a length corresponding to the value obtained by subtracting the allowable deviation width G from the target object width H. Note that the target object width H also has an error, so in this case, it is preferable that the target object width H be the smallest value within the allowable error range. Alternatively, it is preferable that the widthwise separation distance D be set to a length obtained by subtracting the allowable deviation width G and the maximum negative tolerance "α" from the target object width H, where "α" is the maximum tolerance on the negative side of the standard value of the target object width H.

[0031] As shown in FIG. 5 , the inter-unit separation distance F, which is the separation distance between the first unit 1 (first sensor S1) and the second unit 2 (second sensor S2) along the passing direction Y, is set to be shorter than the length of the target object TB along the passing direction Y. This is because, as described above, while the target object TB passes through the intrusion detection surface P, at least one of the first detection state ST1 and the second detection state ST2 is established, thereby disabling the intrusion detection sensor 5. On the other hand, it is preferable that an object B whose intrusion should be restricted does not satisfy this condition. In many cases, it is considered that an object B whose intrusion should be restricted, such as a person, is almost never detected simultaneously in the detection ranges K of the pair of first sensors S1 or the pair of second sensors S2. However, it is also preferable that the object B is not detected simultaneously by the first unit 1 and the second unit 2. For example, the inter-unit separation distance F, which is the separation distance between the first unit 1 and the second unit 2 along the passing direction Y, is set to be greater than the front-to-back thickness of a person's body. As a result, when a person passes through the entry detection surface P, there will be a period during which the person is not detected by either the first unit 1 or the second unit 2, thereby increasing the possibility that the entry detection sensor 5 will be able to detect the entry of a person.

[0032] The following description will be given with reference to the flowchart of FIG. 7 . The control unit 7 first determines whether the invalidation condition is met (#1). Here, as described above with reference to FIG. 6 and other figures, it determines whether the first detection state ST1 is reached, in which both of the pair of first sensors S1 (S1a, S1b) detect the object B. If the control unit 7 determines that the first detection state ST1 is reached, it invalidates the entry detection sensor 5 and starts a timer (#2). As described above, this invalidation may be achieved by stopping the function of the entry detection sensor 5, or by the control unit 7 ignoring the detection result of the entry detection sensor 5. Furthermore, if the detection result of the entry detection sensor 5 is directly transmitted to the management area control unit 9, the control unit 7 may transmit information indicating the invalidation to the management area control unit 9 so that the detection result is ignored by the management area control unit 9.

[0033] For safety reasons, the timer is set to time out and re-enable the entry detection sensor 5 if the disabling continues for a predetermined period of time. For example, if an article transport vehicle stops due to a malfunction or other reason at a position detected by the muting sensor 3, detection at the entry detection surface P will remain disabled. If the article transport vehicle stops at a position detected by the entry detection sensor 5, the article transport vehicle will also prevent entry into the managed area E2, making it difficult for a person to enter the managed area E2 from the general area E1. However, if the article transport vehicle stops before the position detected by the entry detection sensor 5, the entry gate will be open, allowing a person to relatively easily enter the managed area E2 from the general area E1. Because automatic transfer machines and automatic machine tools are likely to be operating in the managed area E2, it is preferable to enable the entry detection sensor 5 in such cases.

[0034] After disabling the intrusion detection sensor 5, the control unit 7 again determines whether the disabling conditions are met (#3). That is, the control unit 7 determines whether at least one of the following conditions is met: a first detection state ST1 in which both of the pair of first sensors S1 (S1a, S1b) detect object B; and a second detection state ST2 in which both of the pair of second sensors S2 (S2a, S2b) detect object B. If either the first detection state ST1 or the second detection state ST2 is met and the timer has not yet timed out (#4), the disabling continues (times t1 to t6 in FIG. 6). If neither the first detection state ST1 nor the second detection state ST2 is met (after time t6 in FIG. 6), or if the timer has timed out (#4), the disabling ends, and the intrusion detection sensor 5 is again enabled (#5).

[0035] As described above, according to this embodiment, in the intrusion detection system 10 that detects an object B entering a predefined area (management area E2), it is possible to appropriately disable the detection of an object B (target object TB) whose entry is permitted.

[0036] Other embodiments will be described below. Note that the configurations of the embodiments described below are not limited to being applied independently, and may be applied in combination with the configurations of other embodiments as long as no contradiction occurs.

[0037] (1) In the above, an example was given in which the intrusion detection sensor 5 is an optical sensor and the muting sensor 3 is an ultrasonic sensor. However, this does not preclude an example in which the intrusion detection sensor 5 is an ultrasonic sensor and the muting sensor 3 is an optical sensor. Furthermore, as long as the intrusion detection sensor 5 and the muting sensor 3 have different detection principles, sensors based on detection principles other than optical and ultrasonic may be used.

[0038] (2) In the above example, the detection principles of the intrusion detection sensor 5 and the muting sensor 3 are different. However, this does not prevent the detection principles of the intrusion detection sensor 5 and the muting sensor 3 from being the same. For example, the intrusion detection sensor 5 may be an optical light curtain, and the muting sensor 3 may also be an optical distance sensor.

[0039] (3) In the above example, the inter-unit separation distance F between the first unit 1 and the second unit 2 along the passing direction Y is greater than the front-to-rear thickness of a human body, which is an object whose entry should be restricted. However, in the case of a human, it is considered unlikely that the human body will be detected simultaneously by both of the pair of first sensors or both of the pair of second sensors. Therefore, there is no prohibition on prioritizing efficiency, etc., and setting the inter-unit separation distance F to be equal to or less than the front-to-rear thickness of the human body.

[0040] (4) In the above example, the path R is formed along a horizontal plane, and the entry detection plane P is set along the vertical direction Z (see FIG. 1). However, the article transport vehicle is not limited to a form that moves horizontally, and may be a form that moves vertically, in which case the entry detection plane P may be set along a horizontal plane. In this case, any direction perpendicular to the passing direction Y can be defined as the width direction X.

[0041] (5) In the above description, an example was given of a first mute period M1 in which the intrusion detection sensor 5 is disabled when at least one of the first detection state ST1 and the second detection state ST2 is established, as in the first mute period M1 shown in FIG. 6 . However, after the intrusion detection sensor 5 no longer detects object B, that is, after time t5, object B will not be detected even if the intrusion detection sensor 5 is not disabled. Therefore, the mute period M may end at time t5 (second mute period M2). In this case, the control unit 7 disables the intrusion detection sensor 5 when at least one of the first detection state and the state in which the intrusion detection state STW and the second detection state are established.

[0042] In the determination during the first mute period M1, the necessity of muting is determined only by the muting sensor 3, whereas in this case, the necessity of muting is determined based on the detection results of both the muting sensor 3 (first unit 1, second unit 2) and the intrusion detection sensor 5, making the system configuration slightly more complicated. Furthermore, if disabling disables the detection function itself of the intrusion detection sensor 5, the second mute period M2 cannot be employed. However, if the second mute period M2 is employed, the intrusion detection sensor 5 can be quickly enabled at the point when muting is no longer necessary.

[0043] [Outline of the embodiment] The outline of the intrusion detection system described above will be briefly described below.

[0044] In one preferred embodiment, an intrusion detection system for detecting an object entering a predetermined area comprises: an intrusion detection sensor that detects whether or not a part of the object is present on an intrusion detection surface that is set in a planar shape of a predetermined range; a muting sensor that detects the object in order to invalidate the detection of the object by the intrusion detection sensor, the muting sensor having a first unit and a second unit; and a control unit that controls operation of the intrusion detection sensor based on the detection result of the muting sensor, wherein a direction perpendicular to the intrusion detection surface is defined as a passing direction, one side of the passing direction is defined as a first passing direction side, and the other side is defined as a second passing direction side, and the first unit comprises a pair of first sensors that are arranged opposite to and spaced apart in a width direction that is a direction parallel to the intrusion detection surface on the first passing direction side, and each of the pair of first sensors detects whether or not the object is present within a predetermined first detection range, and the first detection range is defined as follows: The pair of first sensors extend from each of the pair of first sensors in directions opposing each other in the width direction, and the pair of first detection ranges are set to be spaced apart from each other in the width direction, the second unit has a pair of second sensors arranged opposite each other and spaced apart in the width direction on the second side of the passing direction from the entry detection surface, and each of the pair of second sensors detects whether the object is present within a predetermined second detection range, the second detection range extends from each of the pair of second sensors in directions opposing each other in the width direction, and the pair of second detection ranges are set to be spaced apart from each other in the width direction, and the control unit disables the entry detection sensor when at least one of a first detection state in which both of the pair of first sensors detect the object and a second detection state in which both of the pair of second sensors detect the object is established.

[0045] According to this configuration, muting sensors capable of detecting objects are installed on both the first and second sides of the intrusion detection surface in the passing direction. Therefore, an object approaching the intrusion detection surface along the passing direction can be detected by one of the muting sensors on the first and second sides before the object reaches the intrusion detection surface. Furthermore, if the entire object has passed through the detection range of the muting sensor on one side, and a portion of the object still remains on the intrusion detection surface, the object can be detected by the muting sensor on the other side. Therefore, if the detected object is permitted to pass through the intrusion detection surface, the intrusion detection sensor can be quickly disabled before the object reaches the intrusion detection surface, and the intrusion detection sensor can be appropriately disabled until the object passes the intrusion detection surface. Furthermore, according to this configuration, the first sensor constituting the muting sensor is disposed on the first side of the intrusion detection surface in the passing direction, and the second sensor is disposed on the second side of the intrusion detection surface in the passing direction. That is, the detection ranges of the first and second sensors do not intersect, but are parallel to the intrusion detection surface. Therefore, even in a relatively small installation space, it is easy to appropriately set the positional relationship between the detection position of the muting sensor and the detection position of the intrusion detection sensor along the passage direction. Furthermore, by setting a pair of first detection ranges to be spaced apart from each other in the width direction and a pair of second detection ranges to be spaced apart from each other in the width direction, the intrusion detection sensor is not disabled unless both of the pair of first sensors detect an object or both of the pair of second sensors detect an object. Therefore, the intrusion detection sensor can be enabled for objects that do not fall within both of the pair of first detection ranges and both of the pair of second detection ranges. Therefore, the intrusion detection sensor can appropriately detect the passage of objects whose entry is not permitted. Thus, this configuration provides a technology that can appropriately disable the detection of objects whose entry is permitted in an intrusion detection system that detects objects entering a predetermined area.

[0046] Furthermore, it is preferable that the first separation distance, which is the widthwise separation distance between a pair of the first detection ranges, and the second separation distance, which is the widthwise separation distance between a pair of the second detection ranges, are set based on the target object width, which is the length along the widthwise direction of the target object that is allowed to pass through the entry detection surface, and the allowable deviation width, which is the range within which positional deviation in the widthwise direction is allowed when the target object moves along the passing direction.

[0047] According to this configuration, the first separation distance and the second separation distance can be appropriately set in consideration of the length of the target object in the width direction and the positional deviation of the target object in the width direction while it is moving, and therefore the target object can be appropriately detected by the muting sensor.

[0048] Preferably, the first separation distance and the second separation distance are set to lengths corresponding to a value obtained by subtracting the allowable deviation width from the target object width.

[0049] According to this configuration, even if the target object is misaligned in the width direction within the range of the allowable deviation width, the target object falls within both of the pair of first detection ranges and both of the pair of second detection ranges, so the muting sensor can properly detect the target object regardless of the misalignment of the target object in the width direction.

[0050] Preferably, the distance between the first unit and the second unit along the passing direction is greater than the thickness of a human body in the front-to-rear direction.

[0051] The object whose passage is restricted on such an intrusion detection surface may be a person. In many cases, the length along the passage direction of an object permitted to pass through the intrusion detection surface is greater than the thickness of a person's body in the front-to-back direction. Therefore, when either the first unit or the second unit detects an object, the intrusion detection sensor is disabled, thereby controlling the operation of the intrusion detection sensor so that the object permitted to pass can pass appropriately. Furthermore, because the first unit and the second unit are spaced apart along the passage direction by a distance greater than the thickness of a person's body in the front-to-back direction, when a person passes through the intrusion detection surface, a period occurs during which the person is not detected by either the first unit or the second unit, thereby increasing the likelihood that the intrusion detection sensor will detect the intrusion of a person.

[0052] Preferably, the intrusion detection sensor and the muting sensor are sensors that detect the object using different detection principles.

[0053] For example, if the intrusion detection sensor and the muting sensor are both optical sensors, light reflected (including diffuse reflection) by objects that are permitted to pass through the intrusion detection surface, such as the surface of an article transport vehicle or fastening members such as screws, may reduce the detection accuracy of the muting sensor or cause false detection. Furthermore, if the article transport vehicle is an automated guided vehicle, for example, it is often equipped with an optical obstacle sensor to prevent contact or collision with workers or other objects. Light emitted from such obstacle sensors may enter the muting sensor, reducing the detection accuracy. Furthermore, if the intrusion detection sensor and the muting sensor are both ultrasonic sensors, interference or other factors may similarly reduce the detection accuracy or cause false detection. When the detection principle of the intrusion detection sensor and the detection principle of the muting sensor are different, as in this configuration, the above-mentioned reduction in accuracy and false detection are suppressed.

[0054] Preferably, the intrusion detection sensor is an optical sensor, and the muting sensor is an ultrasonic sensor.

[0055] Optical sensors can easily set a thin, planar detection range. On the other hand, ultrasonic sensors tend to have a larger detection range than optical sensors, allowing them to detect the presence or absence of an object over a certain range. Therefore, ultrasonic sensors are less susceptible to the shape of an object when detecting the presence or absence of an object that is permitted to pass through the intrusion detection surface. This prevents the intrusion detection sensor from mistakenly detecting an object that should be permitted to pass due to a detection delay by the muting sensor. Therefore, when the intrusion detection sensor is an optical sensor and the muting sensor is an ultrasonic sensor, it is possible to appropriately control the operation of the intrusion detection sensor and appropriately detect an object on the intrusion detection surface.

[0056] 1: First unit 2: Second unit 3: Muting sensor 5: Intrusion detection sensor 7: Control unit 10: Intrusion detection system B: Object D: Width direction separation distance (separation distance in the width direction) D1: First separation distance D2: Second separation distance E2: Control area (predetermined area) F: Inter-unit separation distance (separation distance along the passing direction) G: Allowable deviation width H: Target object width K: Detection range K1: First detection range K2: Second detection range P: Intrusion detection surface S1: First sensor S2: Second sensor ST1: First detection state ST2: Second detection state TB: Target object X: Width direction Y: Passing direction Y1: First side in the passing direction Y2: Second side in the passing direction

Claims

1. An intrusion detection system that detects an object entering a predetermined area, comprising: an intrusion detection sensor that detects whether or not a part of the object is present on an intrusion detection surface that is set in a planar shape of a predetermined range; a muting sensor that detects the object in order to invalidate the detection of the object by the intrusion detection sensor, the muting sensor having a first unit and a second unit; and a control unit that controls the operation of the intrusion detection sensor based on the detection result of the muting sensor, wherein a direction perpendicular to the intrusion detection surface is defined as a passing direction, one side of the passing direction is defined as a first passing direction side, and the other side is defined as a second passing direction side, and the first unit comprises a pair of first sensors that are arranged opposite to and spaced apart in the width direction that is a direction parallel to the intrusion detection surface on the first passing direction side, and each of the pair of first sensors detects whether or not the object is present within a predetermined first detection range, an intrusion detection system in which the first detection range extends from each of the pair of first sensors in a direction in which the pair of first sensors face each other in the width direction, and the pair of first detection ranges are set to be spaced apart from each other in the width direction; the second unit includes a pair of second sensors arranged opposite each other and spaced apart in the width direction on the second side of the passing direction with respect to the intrusion detection surface, and each of the pair of second sensors detects whether the object is present within a predetermined second detection range; the second detection range extends from each of the pair of second sensors in a direction in which the pair of second sensors face each other in the width direction, and the pair of second detection ranges are set to be spaced apart from each other in the width direction; and the control unit disables the intrusion detection sensor when at least one of a first detection state in which both of the pair of first sensors detect the object and a second detection state in which both of the pair of second sensors detect the object is established.

2. The intrusion detection system described in claim 1, wherein the first separation distance, which is the separation distance in the width direction between a pair of the first detection ranges, and the second separation distance, which is the separation distance in the width direction between a pair of the second detection ranges, are set based on the target object width, which is the length along the width direction of the target object that is allowed to pass through the intrusion detection surface, and the allowable deviation width, which is the range within which positional deviation in the width direction is allowed when the target object moves along the passing direction.

3. The intrusion detection system according to claim 2, wherein the first separation distance and the second separation distance are set to lengths corresponding to a value obtained by subtracting the allowable deviation width from the target object width.

4. An intrusion detection system as described in any one of claims 1 to 3, wherein the distance between the first unit and the second unit along the passage direction is greater than the thickness of a person's body in the front-to-back direction.

5. An intrusion detection system according to any one of claims 1 to 4, wherein the intrusion detection sensor and the muting sensor are sensors that detect the object using different detection principles.

6. The intrusion detection system according to claim 5, wherein the intrusion detection sensor is an optical sensor and the muting sensor is an ultrasonic sensor.

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