Front monitoring system, front monitoring device, front monitoring method and program

Abstract

To set a monitoring area appropriately in response to changes in a length of a track that can be detected viewed from a moving body when the track is detected in real time while the moving body traveling along the track is traveling.SOLUTION: A front monitoring system comprises track detection means that is mounted on a moving body traveling along a track and detects a track ahead in real time while the moving body is traveling, monitoring target determination means that sets the farthest point of the track detected by the track detection means as a monitoring target, monitoring means that monitors the monitoring target, and obstacle detection means that detects obstacles on the basis of monitoring results of the monitoring means.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a forward monitoring system, a forward monitoring device, a forward monitoring method, and a program. [Background technology]

[0002] Patent Document 1 discloses a forward monitoring device that monitors the traveling direction of a train and detects obstacles. Specifically, the monitoring range monitored by a monitoring unit composed of a stereo camera, LiDAR (Light Detection and Ranging), RADAR (Radio Detection and Ranging), etc. is temporarily moved closer to the train so that objects along the line, such as traffic lights, buildings, and natural objects, such as trees and cliffs, are not mistakenly recognized as obstacles. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2022 / 003958 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when detecting the track in real time while a train is running, the detectable length of the track varies due to various disturbances. For example, in bad weather such as heavy rain or thick fog, the detectable length of the track may become extremely short.

[0005] An object of the present disclosure is to provide a technology for appropriately setting a monitoring area in response to changes in the detectable length of the track as seen from a moving body when the moving body detects the track in real time while traveling along the track. [Means for solving the problem]

[0006] a track detection means mounted on a moving body that travels along a track and configured to detect a track ahead of the moving body in real time while the moving body is traveling; a monitoring target determination means for determining the farthest point of the trajectory detected by the trajectory detection means as a monitoring target; A monitoring means for monitoring the monitoring target; an obstacle detection means for detecting an obstacle based on a monitoring result by the monitoring means; Including, A forward looking system is provided.

[0007] a track detection means mounted on a moving body that travels along a track and configured to detect a track ahead of the moving body in real time while the moving body is traveling; a monitoring target determination means for determining the farthest point of the trajectory detected by the trajectory detection means as a monitoring target; A monitoring means for monitoring the monitoring target; an obstacle detection means for detecting an obstacle based on a monitoring result by the monitoring means; Including, A forward looking system is provided.

[0008] The system is mounted on a moving object that travels along a track and detects the track ahead in real time while the moving object is traveling. determining the farthest point of the detected orbit as a monitoring target; Monitor the monitoring target; Detecting obstacles based on the monitoring results, A forward looking method is provided.

[0009] Computer, a track detection means mounted on a moving body that travels along a track and configured to detect a track ahead of the moving body in real time while the moving body is traveling; a monitoring target determination means for determining the farthest point of the trajectory detected by the trajectory detection means as a monitoring target; A monitoring means for monitoring the monitoring target; an obstacle detection means for detecting an obstacle based on a monitoring result by the monitoring means; A program is provided to function as a Effect of the Invention

[0010] When a moving body traveling along a track detects the track in real time while the moving body is traveling, the monitoring area can be appropriately set in response to changes in the detectable length of the track as seen from the moving body. [Brief description of the drawings]

[0011] [Figure 1] FIG. 2 is a block diagram of a forward monitoring system. [Diagram 2] FIG. 2 is a block diagram of a forward monitoring device. [Diagram 3] 13 is a graph showing the variation in detection length. [Figure 4] 4 is a control flow of the forward monitoring device. [Diagram 5] FIG. 2 is a diagram showing a case where a processing circuit provided in a forward monitoring device is configured with a processor and a memory. [Figure 6] FIG. 13 is a diagram showing a case where a processing circuit provided in the forward monitoring device is configured with dedicated hardware. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] (Summary of the Disclosure) First, an overview of the present disclosure will be described. Fig. 1 is a block diagram of a forward monitoring system 100. As shown in Fig. 1, the forward monitoring system 100 includes a trajectory detection means 101, a monitoring target determination means 102, a monitoring means 103, and an obstacle detection means 104.

[0013] The trajectory detection means 101 is mounted on a moving object that runs along a trajectory, and detects the trajectory ahead in real time while the moving object is running.

[0014] The monitoring target determining means 102 determines the farthest point of the trajectory detected by the trajectory detecting means 101 as the monitoring target.

[0015] The monitoring means 103 monitors the monitoring target.

[0016] The obstacle detection means 104 detects an obstacle based on the monitoring result by the monitoring means 103 .

[0017] According to the above configuration, when a moving body traveling along a track detects the track in real time while traveling, it is possible to appropriately set a monitoring area in response to changes in the detectable length of the track as seen by the moving body.

[0018] (First embodiment) Hereinafter, a first embodiment of the present disclosure will be described. FIG. 2 shows a block diagram of the forward monitoring device 1. As shown in FIG. 2, the forward monitoring device 1 is mounted on a train 2. The train 2 runs along a track 3. When the train 2 runs on the track 3, the train 2 uses the forward monitoring device 1 to monitor whether or not there is an obstacle on the track 3 in the traveling direction. The train 2 is a specific example of a moving body. The track 3 is a specific example of a track. The train 2 includes the forward monitoring device 1, a train control device 4, and an output device 5. The forward monitoring device 1 is connected to the train control device 4 and the output device 5. The forward monitoring device 1 includes a monitoring length determination unit 10, a track detection unit 11, a monitoring point determination unit 12, a monitoring unit 13, an obstacle detection unit 14, a first warning processing execution unit 15, and a second warning processing execution unit 16.

[0019] The train control device 4 detects the position of the train 2 using a ground coil installed on the ground and an on-board coil mounted on the train 2. The train control device 4 may detect the position of the train 2 by integrating the number of rotations of the wheels of the train 2. The train control device 4 detects the running speed of the train 2. Then, the train control device 4 outputs train position information indicating the position of the train 2 and train speed information indicating the running speed of the train 2 to the forward monitoring device 1.

[0020] The output device 5 typically includes a monitor or a speaker.

[0021] The monitoring length determination unit 10 determines the monitoring length based on the train speed information output from the train control device 4. The monitoring length means the length of the track 3 between the train 2 and the monitoring point. The monitoring point is a point set on the track 3. The monitoring point is a point set along the track 3. The monitoring length is a specific example of the first length. The monitoring length determination unit 10 typically increases the monitoring length when the speed of the train 2 is high, and decreases the monitoring length when the speed of the train 2 is low. Specifically, when the speed of the train 2 is 120 kilometers per hour, the monitoring length determination unit 10 determines the monitoring length to be 600 meters. Similarly, when the speed of the train 2 is 60 kilometers per hour, the monitoring length determination unit 10 determines the monitoring length to be 200 meters. In this way, the monitoring length determination unit 10 determines the monitoring length based on the running speed of the train 2. The monitoring length determination unit 10 may determine the monitoring length according to the braking performance of the braking device, the weather, and the like in addition to the speed of the train 2.

[0022] The track detection unit 11 detects the track 3 ahead in real time while the train 2 is running. The track detection unit 11 detects the area ahead of the train 2 in real time while the train 2 is running. The track detection unit 11 typically detects the track 3 ahead in real time while the train 2 is running based on a two-dimensional image acquired while the train 2 is running or a three-dimensional point cloud acquired while the train 2 is running.

[0023] The track detection unit 11 may typically generate a three-dimensional point cloud using a LiDAR, a RADAR, a stereo camera, or a combination thereof. Alternatively, the track detection unit 11 may generate a three-dimensional point cloud by SfM (Structure from Motion) from a plurality of two-dimensional images obtained by capturing images every 10 milliseconds, for example. The track detection unit 11 detects a track portion from the acquired three-dimensional point cloud by object recognition such as semantic segmentation, and generates track position information indicating the position of the detected track 3. The track position information is information indicating the latitude and longitude of the track 3 detected by the track detection unit 11. The track position information typically includes longitude and latitude information of each of a plurality of points defined along the track 3. A plurality of points through which the track 3 passes can be specified by the plurality of pieces of longitude and latitude information. When the track detection unit 11 detects the track 3 using a LiDAR, the track detection unit 11 sets the scanning density of the LiDAR as the track detection scanning density. The track detection scanning density is a specific example of the first scanning density. The scanning density may be defined as the number of ranging points per unit cubic angle as seen from the LiDAR. The scanning density may also be defined as the inverse of the angle between two line segments connecting two ranging points successively acquired by the LiDAR to the LiDAR. The track detection unit 11 defines a FoV (Field of View) when detecting the track 3 as the track detection FoV. The track detection FoV is a specific example of the first FoV.

[0024] The monitoring point determination unit 12 determines the farthest point of the track 3 detected by the track detection unit 11 as a monitoring point. The monitoring point is a specific example of a monitoring target. Here, the detected length as the length of the track 3 detected by the track detection unit 11 will repeatedly fluctuate due to the radius of curvature of the track 3, and due to obstacles and weather disturbances. For example, when heavy rain or thick fog occurs, the length of the track 3 detected by the track detection unit 11 is considered to be significantly shorter. The detected length is the length of the track 3 from the train 2 to the farthest point of the track 3 detected by the track detection unit 11. FIG. 3 is a graph showing the fluctuation of the detected length with the detected length on the vertical axis and time on the horizontal axis. As shown in FIG. 3, from time t0 to time t1, the detected length is longer than 600 meters, which is an example of a monitoring length. On the other hand, after time t1, the detected length is shorter than 600 meters. When the detected length is longer than the monitoring length, the monitoring point determination unit 12 determines the point where the length of the track 3 seen from the train 2 is the monitoring length as a monitoring point. On the other hand, when the detected length is shorter than the monitoring length, the monitoring point determination unit 12 determines the farthest point of the track 3 detected by the track detection unit 11 as the monitoring point. The monitoring point determination unit 12 calculates the longitude and latitude of the monitoring point based on the track position information.

[0025] The monitoring unit 13 monitors the monitoring point determined by the monitoring point determination unit 12. The monitoring unit 13 typically monitors the monitoring point using LiDAR. At this time, the monitoring unit 13 controls the scanning direction of the LiDAR so that the scanning direction of the LiDAR faces the monitoring point. The monitoring unit 13 also sets the scanning density of the LiDAR as the monitoring scanning density. The monitoring scanning density is higher than the track detection scanning density. The monitoring scanning density is a specific example of the second scanning density. The monitoring unit 13 sets the FoV when monitoring the monitoring point as the monitoring FoV. The monitoring FoV is a specific example of the second FoV. The monitoring FoV is narrower than the track detection FoV.

[0026] The obstacle detection unit 14 detects obstacles based on the monitoring results by the monitoring unit 13. Specifically, the obstacle detection unit 14 detects obstacles on the track 3 based on the three-dimensional point cloud generated by the monitoring unit 13. For example, when the obstacle detection unit 14 detects a foreign object in a space through which the train 2 passes, the obstacle detection unit 14 may detect the foreign object as an obstacle that impedes the travel of the train 2. Examples of obstacles include people, vehicles, placed stones, fallen rocks, and fallen trees.

[0027] The first warning process execution unit 15 executes a warning process when the state in which the detection length is shorter than the monitoring length continues. Specifically, the first warning process execution unit 15 executes a warning process when the state in which the detection length is shorter than the monitoring length continues for a predetermined time or more. The predetermined time may typically be any time between several tens of seconds and several minutes. For example, when the detection length is shortened due to the presence of a building around the track 3, the state in which the detection length is shorter than the monitoring length continues for at most several seconds. Even in such a case, if the warning process is executed each time, the warning process may be repeated many times. Therefore, by executing the warning process only when the state in which the detection length is shorter than the monitoring length continues for a predetermined time or more, unnecessary warning processes are excluded, and the warning process can be executed only when the detection length is shortened due to weather or the like.

[0028] When the output device 5 is a monitor, the first warning process execution unit 15 executes a warning process to cause the output device 5 to display a warning screen indicating a deceleration instruction. When the output device 5 is a speaker, the first warning process execution unit 15 executes a warning process to cause the output device 5 to output an alarm sound indicating a deceleration instruction. When the first warning process execution unit 15 instructs the train 2 to decelerate, the braking distance of the train 2 is shortened, so that the train 2 can be stopped appropriately even if the detection length is short. The first warning process execution unit 15 may output a deceleration command or a stop command to the train control device 4.

[0029] The second warning process execution unit 16 executes a warning process when the obstacle detection unit 14 detects an obstacle. When the output device 5 is a monitor, the second warning process execution unit 16 executes a warning process to cause the output device 5 to display a warning screen indicating the presence of an obstacle ahead. When the output device 5 is a speaker, the second warning process execution unit 16 executes a warning process to cause the output device 5 to output an alarm sound indicating the presence of an obstacle ahead. The second warning process execution unit 16 may output a deceleration command or a stop command to the train control device 4.

[0030] Next, the operation of the forward monitoring device 1 will be described with reference to FIG.

[0031] S100: First, the track detection unit 11 detects the track 3 ahead in real time while the train 2 is traveling.

[0032] S110: Next, the monitoring length determination unit 10 determines the monitoring length based on the train speed information output from the train control device 4.

[0033] S120: Next, the monitoring point determination unit 12 determines monitoring points based on the detection length and the monitoring length.

[0034] S130: Next, the first warning process executing unit 15 determines whether or not the state in which the detected length is shorter than the monitoring length continues.

[0035] S140: If the answer is YES in step S130, the first warning process execution unit 15 executes a warning process to instruct deceleration, and the process returns to step S100.

[0036] S150: If the answer is NO in step S130, the monitoring unit 13 monitors the monitoring point determined by the monitoring point determination unit 12.

[0037] S160: Next, the obstacle detection unit 14 detects an obstacle based on the monitoring result by the monitoring unit 13.

[0038] S170: If the obstacle detection unit 14 detects an obstacle in step S160, the second warning process execution unit 16 executes a warning process indicating the presence of an obstacle ahead, and returns the process to step S100. On the other hand, if the obstacle detection unit 14 does not detect an obstacle in step S160, the second warning process execution unit 16 returns the process to step S100.

[0039] The first embodiment has been described above. The first embodiment has the following features.

[0040] The forward monitoring device 1 (forward monitoring system) includes a track detection unit 11 (track detection), a monitoring point determination unit 12 (monitoring target determination means), a monitoring unit 13 (monitoring means), and an obstacle detection unit 14 (obstacle detection means). The track detection unit 11 is mounted on a train 2 (mobile body) traveling along a track 3 (track), and detects the track 3 ahead in real time while the train 2 is traveling. The monitoring point determination unit 12 sets the farthest point of the track 3 detected by the track detection unit 11 as a monitoring point (monitoring target). The monitoring unit 13 monitors the monitoring target. The obstacle detection unit 14 detects an obstacle based on the monitoring result by the monitoring unit 13. According to the above configuration, when the train 2 traveling along the track 3 detects the track 3 in real time while traveling, the monitoring area can be appropriately set in response to a change in the detectable length of the track 3 as seen from the train 2.

[0041] Furthermore, when the detected length, which is the length of the track from the train 2 to the farthest point, is longer than the monitoring length (first length), the monitoring point determination unit 12 determines the point where the length of the track 3 from the train 2 is the monitoring length as the monitoring point. With the above configuration, the accuracy of the three-dimensional point cloud generated by the monitoring unit 13 can be guaranteed.

[0042] The forward monitoring device 1 also includes a first warning process execution unit 15. The first warning process execution unit 15 executes a warning process when the length of the track 3 between the train 2 and the farthest point continues to be shorter than the monitoring length. With the above configuration, it is possible to execute an appropriate process when recovery of the detected length is not expected due to weather or the like.

[0043] Moreover, the forward monitoring device 1 further includes a monitoring length determination unit 10 (length determination means) that determines the monitoring length based on the traveling speed of the train 2. According to the above configuration, an appropriate monitoring length can be set based on the traveling speed of the train 2.

[0044] The track detection unit 11 detects the track 3 based on the result of scanning the area ahead of the train 2 at a track detection scanning density (first scanning density). Meanwhile, the monitoring unit 13 monitors the monitoring point based on the result of scanning at a monitoring scanning density (second scanning density) higher than the track detection scanning density. With the above configuration, the track 3 can be detected with a wider FoV and obstacles can be detected with higher accuracy.

[0045] Next, the hardware configuration of the forward monitoring device 1 will be described. As described above, the monitoring unit 13 is a sensor such as LiDAR, RADAR, or a stereo camera. The monitoring length determination unit 10, the trajectory detection unit 11, the monitoring point determination unit 12, the obstacle detection unit 14, the first warning processing execution unit 15, and the second warning processing execution unit 16 are realized by processing circuits. The processing circuit may be a processor and memory that executes a program stored in a memory, or may be dedicated hardware.

[0046] FIG. 5 is a diagram showing an example in which the processing circuit of the forward monitoring device 1 is configured with a processor and a memory. When the processing circuit is configured with a processor 1000 and a memory 1001, each function of the processing circuit of the forward monitoring device 1 is realized by software, firmware, or a combination of software and firmware. The software or firmware is written as a program and stored in the memory 1001. In the processing circuit, each function is realized by the processor 1000 reading and executing the program stored in the memory 1001. That is, the processing circuit includes a memory 1001 for storing a program that results in the processing of the forward monitoring device 1 being executed. It can also be said that these programs cause a computer to execute the procedures and methods of the forward monitoring device 1.

[0047] Here, the processor 1000 may be a CPU (Central Processing Unit), a processing device, an arithmetic device, a microprocessor, a microcomputer, or a DSP (Digital Signal Processor), etc. Also, the memory 1001 may be, for example, a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, an EPROM (Erasable Programmable ROM), an EEPROM (Electrically EPROM), or other non-volatile or volatile semiconductor memory, a magnetic disk, a flexible disk, an optical disk, a compact disk, a mini disk, or a DVD (Digital Versatile Disc), etc.

[0048] Fig. 6 is a diagram showing an example in which the processing circuit of the forward monitoring device 1 is configured with dedicated hardware. When the processing circuit is configured with dedicated hardware, the processing circuit 1002 shown in Fig. 6 corresponds to, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or a combination of these. Each function of the forward monitoring device 1 may be realized by the processing circuit 1002 on a function-by-function basis, or each function may be realized collectively by the processing circuit 1002.

[0049] It should be noted that the functions of the forward monitoring device 1 may be partially realized by dedicated hardware and partially realized by software or firmware. In this manner, the processing circuit can realize each of the above-mentioned functions by dedicated hardware, software, firmware, or a combination of these.

[0050] Although the present disclosure has been described above with reference to the first embodiment, the present disclosure is not limited to the above-mentioned first embodiment. Various modifications that can be understood by a person skilled in the art can be made to the configuration and details of the present disclosure within the scope of the present disclosure.

[0051] Each drawing is merely an example for describing one or more embodiments. Each drawing may relate not only to one particular embodiment, but to one or more other embodiments. As can be understood by those skilled in the art, various features or steps described with reference to any one drawing may be combined with features or steps shown in one or more other drawings to create an embodiment not explicitly shown or described, for example. Not all features or steps shown in any one drawing are necessary to describe an exemplary embodiment, and some features or steps may be omitted. The order of steps described in any drawing may be changed as appropriate.

[0052] A part or all of the above-described embodiments can be described as, but is not limited to, the following supplementary notes. (Appendix 1) a track detection means mounted on a moving body that travels along a track and configured to detect a track ahead of the moving body in real time while the moving body is traveling; a monitoring target determination means for determining the farthest point of the trajectory detected by the trajectory detection means as a monitoring target; A monitoring means for monitoring the monitoring target; an obstacle detection means for detecting an obstacle based on a monitoring result by the monitoring means; Including, Forward monitoring system. (Appendix 2) When the length of the trajectory from the moving body to the farthest point is longer than a first length, the monitoring target determination means determines, as the monitoring target, a point where the length of the trajectory from the moving body becomes the first length. 2. A forward monitoring system as described in claim 1. (Appendix 3) a warning process execution means for executing a warning process when a state in which the length of the trajectory from the moving body to the farthest point remains shorter than the first length is continued, 2. A forward monitoring system as described in claim 2. (Appendix 4) further comprising a length determination means for determining the first length based on a traveling speed of the moving body; 4. The forward monitoring system according to claim 2 or 3. (Appendix 5) the trajectory detection means detects the trajectory based on a scanning result obtained by scanning a front of the moving object at a first scanning density; the monitoring means monitors the monitoring target based on a scanning result obtained by scanning at a second scanning density higher than the first scanning density. 2. A forward monitoring system as described in claim 1. (Appendix 6) a track detection means mounted on a moving body that travels along a track and configured to detect a track ahead of the moving body in real time while the moving body is traveling; a monitoring target determination means for determining the farthest point of the trajectory detected by the trajectory detection means as a monitoring target; A monitoring means for monitoring the monitoring target; an obstacle detection means for detecting an obstacle based on a monitoring result by the monitoring means; Including, Forward monitoring device. (Appendix 7) It is mounted on a moving object that travels along a track and detects the track ahead in real time while the moving object is traveling. determining the farthest point of the detected orbit as a monitoring target; Monitor the monitoring target; Detecting obstacles based on the monitoring results, Forward monitoring method. (Appendix 8) Computer, a track detection means mounted on a moving body that travels along a track and configured to detect a track ahead of the moving body in real time while the moving body is traveling; a monitoring target determination means for determining the farthest point of the trajectory detected by the trajectory detection means as a monitoring target; A monitoring means for monitoring the monitoring target; an obstacle detection means for detecting an obstacle based on a monitoring result by the monitoring means; A program that functions as a

[0053] Some or all of the elements (e.g., configurations and functions) described in Supplementary Notes 2 to 5 that are dependent on Supplementary Note 1 may also be dependent on Supplementary Notes 6, 7, and 8 in the same dependent relationship as Supplementary Notes 2 to 5. Some or all of the elements described in any Supplementary Note may be applied to various hardware, software, recording means for recording software, systems, and methods. [Explanation of symbols]

[0054] 1 Forward monitoring device 2. Train 3 railroad tracks 4 Train control device 5 Output Devices 10 Monitoring length determination unit 11 Trajectory detection section 12 Monitoring Point Determination Division 13 Monitoring Department 14 Obstacle detection section 15 First warning processing execution unit 16 Second warning processing execution unit

Claims

1. a track detection means mounted on a moving body that travels along a track and configured to detect a track ahead of the moving body in real time while the moving body is traveling; a monitoring target determination means for determining the farthest point of the trajectory detected by the trajectory detection means as a monitoring target; A monitoring means for monitoring the monitoring target; an obstacle detection means for detecting an obstacle based on a monitoring result by the monitoring means; Including, Forward monitoring system.

2. the monitoring target determination means, when the length of the trajectory from the moving body to the farthest point is longer than a first length, determines, as the monitoring target, a point where the length of the trajectory from the moving body becomes the first length; The forward facing monitoring system according to claim 1 .

3. a warning process execution means for executing a warning process when a state in which the length of the trajectory from the moving body to the farthest point remains shorter than the first length is continued. The forward facing monitoring system according to claim 2 .

4. a length determining means for determining the first length based on a traveling speed of the moving object, 4. A forward monitoring system according to claim 2 or 3.

5. the trajectory detection means detects the trajectory based on a scanning result obtained by scanning a front of the moving object at a first scanning density; the monitoring means monitors the monitoring target based on a scanning result obtained by scanning at a second scanning density higher than the first scanning density. The forward facing monitoring system according to claim 1 .

6. a track detection means mounted on a moving body that travels along a track and configured to detect a track ahead of the moving body in real time while the moving body is traveling; a monitoring target determination means for determining the farthest point of the trajectory detected by the trajectory detection means as a monitoring target; A monitoring means for monitoring the monitoring target; an obstacle detection means for detecting an obstacle based on a monitoring result by the monitoring means; Including, Forward monitoring device.

7. The system is mounted on a moving object that travels along a track and detects the track ahead in real time while the moving object is traveling. determining the farthest point of the detected orbit as a monitoring target; Monitor the monitoring target; Detecting obstacles based on the monitoring results, Forward monitoring method.

8. Computer, a track detection means mounted on a moving body that travels along a track and configured to detect a track ahead of the moving body in real time while the moving body is traveling; a monitoring target determination means for determining the farthest point of the trajectory detected by the trajectory detection means as a monitoring target; A monitoring means for monitoring the monitoring target; an obstacle detection means for detecting an obstacle based on a monitoring result by the monitoring means; A program that functions as a

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