Device and method for inspecting wire rope

Abstract

To provide a device and a method for inspecting a wire rope, which can easily and accurately calculate a wire rope position.SOLUTION: An imaging device 3 continuously captures a wire rope 5. A luminance difference calculation unit 42 calculates a luminance difference for each frame from continuously captured image signals, and acquires motion start time and stop time of the wire rope 5 from the luminance difference for each frame. A rope position calculation unit 43 calculates a traveling distance of the wire rope on the basis of the motion start time and the stop time and a speed profile (a mathematical expression of acceleration and jerk per time) preset in a traveling command, and calculates a rope position at each time from a motion start (initial) position or a stop position on the basis of the traveling distance.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a wire rope inspection device and method. [Background technology]

[0002] Conventionally, periodic inspection of elevators and the like includes inspecting the cage and the wire rope that suspends the cage. In particular, visual inspection is required for elevator wire ropes under the periodic reporting system of the Building Standards Act. In addition, photographs must be attached when reporting inspection results. For this reason, wire rope inspections are generally performed visually, and photographs are taken for the report. In this case, the method of visually measuring the wire rope diameter in the field is to measure the outer diameter of the wire rope with a vernier caliper.

[0003] However, elevators are basically in operation all the time, so inspection work cannot take up much time. Conventionally, general visual wire rope inspection is a manual task, so unless you are an experienced worker, it is difficult to complete the inspection in a short time, and there is a problem that defects are easily overlooked.

[0004] Therefore, for example, Patent Document 1 discloses a technology in which a light beam is emitted from a laser light source while feeding the wire rope, and the outer diameter of the wire rope is measured based on the output signal of a light receiving section that receives the light beam.

[0005] Furthermore, Patent Document 2 discloses a technology in which a camera continuously photographs a wire rope while the wire rope is running, the photographed images of the wire rope are associated with the position of the wire rope, and the outer diameter of the wire rope is measured by image processing of the photographed images. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2008-214037 A [Patent Document 2] JP 2011-132010 A Summary of the Invention [Problem to be solved by the invention]

[0007] Incidentally, when an abnormality is found in a wire rope during a wire rope inspection, it is necessary to run the wire rope to a location where the position of the abnormality can be visually confirmed and take a separate photograph. In other words, in a wire rope inspection, it is necessary to know the position of the wire rope with the abnormality.

[0008] However, although Patent Document 1 discloses grasping the outer shape from the silhouette in the image, it does not mention detecting the wire rope position. Also, Patent Document 2 discloses detecting the wire rope position, but finds the current wire rope position by performing image processing such as projective transformation on the captured image to calculate the actual movement amount of the wire rope, which requires complex calculation processing.

[0009] Also, in addition to the image capturing device that captures images of abnormalities in the wire rope, it is possible to attach a sensor such as an encoder to the wire rope, the drive mechanism, etc., in order to measure the wire rope position. However, there is a problem in that attaching a sensor to the wire rope, the drive mechanism, etc., every time a periodic inspection is performed is very time-consuming and places a burden on the worker.

[0010] Therefore, an object of the present invention is to provide a wire rope inspection device and inspection method that can easily and accurately calculate the wire rope position. [Means for solving the problem]

[0011] The wire rope inspection device of the first invention for solving the above problems is characterized in that it comprises an imaging unit that continuously images the wire rope while running the wire rope in accordance with a running command, a brightness difference calculation unit that determines the brightness of the rope area in the captured image by the imaging unit and calculates the time when the wire rope starts to move and the time when the wire rope stops based on the temporal change in brightness, and a rope calculation unit that calculates the position of the wire rope based on the time when the wire rope starts to move and the time when the wire rope stops and a speed profile that is preset in the running command.

[0012] A wire rope inspection device of the second invention for solving the above problems is characterized in that it comprises an imaging unit that continuously images the wire rope while running the wire rope in accordance with a running command, a brightness difference calculation unit that determines the brightness of the rope area in the captured images by the imaging unit and calculates the start time of the wire rope and the stop time of the wire rope based on the temporal change in brightness, a rollback calculation unit that detects rollback, which is running in the opposite direction to the running direction specified by the running command, by calculating the running direction and amount of movement when the start of movement of the wire rope is detected by the brightness difference calculation unit, and a rope calculation unit that calculates the position of the wire rope based on the start time and stop time of the wire rope and a speed profile that is preset in the running command.

[0013] A wire rope inspection method according to a third aspect of the present invention for solving the above problems includes continuously photographing the wire rope while running the wire rope in accordance with a running command, determining the brightness of the rope area in the captured image by the continuous photographing, calculating the start time and stop time of the wire rope based on the temporal change in brightness, and calculating the rope position of the wire rope based on the start time and stop time of the wire rope and a speed profile preset in the running command. Effect of the Invention

[0014] According to the present invention, it is possible to easily and accurately calculate the wire rope position. [Brief description of the drawings]

[0015] [Figure 1] 1 is a block diagram showing a configuration of a wire rope inspection device 1 according to a first embodiment of the present invention. [Diagram 2] 5 is a flowchart for explaining the operation of the wire rope inspection device 1 according to the first embodiment. [Diagram 3] 1 is a schematic diagram showing an example of one frame of a captured image taken by the wire rope inspection device 1 according to the first embodiment. FIG. [Figure 4] FIG. 4 is a conceptual diagram showing an example of a change in luminance of a captured image from the start of movement of a wire rope until the wire rope stops, and an average value thereof, in the first embodiment. [Diagram 5] FIG. 4 is a block diagram showing a configuration of a wire rope inspection device 1 according to a second embodiment of the present invention. [Figure 6] 10 is a flowchart for explaining the operation of the wire rope inspection device 1 according to the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. Note that, in the present invention, a method for detecting an abnormality in the wire rope 5 from a photographed image is used by using an existing technique, and therefore a description thereof will be omitted.

[0017] A. First embodiment FIG. 1 is a block diagram showing the configuration of a wire rope inspection device 1 according to a first embodiment of the present invention. In FIG. 1, the wire rope inspection device 1 is composed of an illumination device 2, an imaging device 3, and a processing device 4. The imaging device 3 may be composed of either a line sensor camera or an area sensor camera. The inspection object is a wire rope 5 used for elevator ropes, cranes, etc. In the illustrated example, one wire rope 5 is shown as the inspection object, but the inspection object is not limited to this, and may be multiple wire ropes arranged in parallel at a predetermined interval.

[0018] During inspection, the wire rope 5 is driven to travel in either the up or down direction by a drive control device (not shown) in accordance with a travel command. The lighting device 2 illuminates the photographing location of the wire rope 5 to be inspected as necessary. The photographing device 3 is fixed near the wire rope 5, and continuously photographs the wire rope 5 traveling in either the up or down direction, and supplies the photographs to the processing device 4 as image signals.

[0019] The processing device 4 is composed of an image input unit 41, a brightness difference calculation unit 42, and a rope position calculation unit 43. The image input unit 41 inputs an image signal of the wire rope 5 continuously photographed by the photographing device 3. The brightness difference calculation unit 42 calculates the brightness difference for each frame from the continuously photographed image signal, and obtains the start time and stop time of the wire rope 5 from the brightness difference for each frame. The rope position calculation unit 43 calculates the running distance of the wire rope based on the start time and stop time and the speed profile (the mathematical expression of acceleration and jerk per time) previously set in the running command, and calculates the rope position at each time from the start (start) position or the stop position based on the running distance. In addition, the running distance can be obtained by calculating, for example, the integral (constant) of the speed from the start (start) position to the steady state + the time of the steady state × the steady speed (constant) + the integral (constant) of the speed from the steady speed to the stop position.

[0020] 2 is a flow chart for explaining the operation of the wire rope inspection device 1 according to the first embodiment. First, during inspection, in response to a travel command, a driving device (not shown) causes the wire rope 5 to travel in either the up or down direction according to a speed profile (a mathematical expression of acceleration and jerk per unit time) that is preset for each facility. The photographing device 3 photographs the wire rope 5 traveling in either the up or down direction, and supplies the photographed image to the processing device 4. The lighting device 2 illuminates the photographed location of the wire rope 5 as necessary.

[0021] In the processing device 4, the image input unit 41 inputs an image signal of the wire rope 5 photographed by the photographing device 3 (step S10). Next, the brightness difference calculation unit 42 calculates the brightness difference between the previous frame and the current frame from the image signal (photographed image) supplied from the image input unit 41 (step S12).

[0022] Here, Fig. 3 is a schematic diagram showing an example of one frame of a captured image captured by the wire rope inspection device 1 according to the first embodiment. In one frame of captured image 6, a wire rope 5 traveling in one direction is captured as a rope region 61. The brightness difference calculation unit 42 first extracts the brightness difference of the rope region 61 in the black part shown in Fig. 3. To extract the brightness difference, only the rope region 61 may be extracted by using a depth image from a camera, which is a known technique and is called a depth image. Specifically, the brightness difference calculation unit 42 finds the brightness difference between the rope region 61 in the previous captured image and the rope region 61 in the current captured image.

[0023] Next, the processing device 4 judges whether the image input is completed (step S14), and if the image input is not completed (NO in step S14), the process returns to step S10 and repeats the above-mentioned process. As a result, the photographing device 3 continuously photographs the wire rope 5 traveling in either the up or down direction until the wire rope 5 starts traveling from a stopped state and stops again, and supplies the photographs as image signals to the image input unit 41 of the processing device 4. The brightness difference calculation unit 42 calculates the brightness difference of the rope region 61 for each frame from the image signal (photographed image) supplied from the image input unit 41.

[0024] Here, Fig. 4 is a conceptual diagram showing an example of the change in luminance of a captured image from the start to the stop of the cable movement and its average value in the first embodiment. Fig. 4 shows a time-series graph of the luminance difference (absolute value) of the rope region 61 calculated for each frame by the luminance difference calculation unit 42. The vertical axis is the luminance difference (absolute value), the horizontal axis is the elapsed time, the solid line 7 is the luminance difference (absolute value), and the dashed line 8 is the smoothed value of the luminance difference.

[0025] On the other hand, when the image input is completed (YES in step S14), the brightness difference calculation unit 42 calculates the movement start time and the stop time of the wire rope 5 based on the brightness difference of the rope region 61 for each frame (step S16). When the brightness difference (smoothed value) shown in Fig. 4 is less than a predetermined threshold (almost zero) in the portion where the wire rope 5 is stopped, the time when the brightness difference becomes equal to or greater than the predetermined threshold is determined as the start of movement (movement start time), and when the brightness difference becomes less than the predetermined threshold again (almost zero) is determined as the stop time.

[0026] Next, the rope position calculation unit 43 calculates the amount of movement of the wire rope 5 at each time based on the start time and stop time and a preset speed profile (formula for acceleration and jerk per time), and calculates the rope position at each time by adding the amount of movement to the start position or by calculating backwards from the stop position.

[0027] According to the above-described first embodiment, the brightness difference is calculated only in the rope area 61 excluding the background, so that erroneous detection of the start and stop of movement due to lateral swaying of the wire rope 5 can be prevented. Moreover, according to the first embodiment, the rope position can be calculated only from the captured image. This eliminates the need for a position measurement sensor such as an encoder, and the rope position can be accurately calculated only by the imaging device 3. Furthermore, even if an abnormality is detected in the wire rope 5, the captured image in which the abnormality was detected can be easily associated with the rope position in which the abnormality was detected, and the wire rope 5 can be easily and accurately moved to a location where the rope position in which the abnormality was detected can be visually confirmed.

[0028] B. Second embodiment FIG. 5 is a block diagram showing the configuration of a wire rope inspection device 1 according to a second embodiment of the present invention. Note that parts corresponding to those in FIG. 1 are given the same reference numerals and their explanations are omitted. This second embodiment differs from the above-mentioned first embodiment in that rollback is calculated when the wire rope 5 starts to move. Rollback is the movement of the elevator (car) due to the difference between the actual load on the elevator (car) immediately after the brake is released and the torque output based on information from the load sensor. Rollback is not a desirable movement. Therefore, this second embodiment is characterized by detecting rollback from a captured image.

[0029] As shown in Fig. 5, the wire rope inspection device 1 includes a rollback calculation unit 44 between the brightness difference calculation unit 42 and the rope position calculation unit 43. When the start of movement of the wire rope 5 is detected in the brightness difference calculation of the pre-processing, the rollback calculation unit 44 calculates the movement direction and the movement amount, and when the movement is opposite to the movement direction of the travel command, outputs a rollback signal according to the rollback amount (movement amount in the opposite direction) to the outside. Optical flow processing, which is a general image processing method, may be used to calculate the movement direction and the movement amount.

[0030] 6 is a flow chart for explaining the operation of the wire rope inspection device 1 according to the second embodiment. First, during inspection, in response to a travel command, a driving device (not shown) causes the wire rope 5 to travel in either the up or down direction according to a speed profile (a mathematical expression of acceleration and jerk per unit time) that is preset for each facility. The photographing device 3 photographs the wire rope 5 traveling in either the up or down direction, and supplies the photographed image to the processing device 4. The lighting device 2 illuminates the photographed location of the wire rope 5 as necessary.

[0031] In the processing device 4, the image input unit 41 inputs an image signal of the wire rope 5 photographed by the photographing device 3 (step S20). Next, the brightness difference calculation unit 42 calculates the brightness difference between the previous frame and the current frame from the image signal (photographed image) supplied from the image input unit 41 (step S22). Next, when the start of movement of the wire rope 5 is detected in the brightness difference calculation of the preprocessing, the rollback calculation unit 44 calculates the movement direction and movement amount, and when the movement is opposite to the commanded movement direction, outputs a rollback signal according to the rollback amount (movement amount in the opposite direction) to the outside (step S24).

[0032] Next, the processing device 4 judges whether the image input has been completed (step S26), and if the image input has not been completed (NO in step S26), the process returns to step S20 and repeats the above-mentioned process. As a result, in accordance with the travel command, the wire rope 5 starts traveling from a stopped state, and until it stops again, the photographing device 3 continuously photographs the wire rope 5 traveling in either the up or down direction, and supplies the photographs as image signals to the image input unit 41 of the processing device 4. The brightness difference calculation unit 42 calculates the brightness difference of the rope region 61 for each frame from the image signal (photographed image) supplied from the image input unit 41.

[0033] On the other hand, when the image input is completed (YES in step S14), the brightness difference calculation unit 42 calculates the movement start time and the stop time of the wire rope 5 based on the brightness difference of the rope area 61 for each frame (step S28).

[0034] Next, the rope position calculation unit 43 calculates the amount of movement of the wire rope 5 at each time based on the start time and stop time and a preset speed profile (formula for acceleration and jerk per time), and calculates the rope position at each time by adding the amount of movement to the start position or by calculating backwards from the stop position.

[0035] According to the above-described second embodiment, in addition to the advantages of the first embodiment, the following advantages are obtained. Conventionally, unintended rollback has been detected using a load sensor or the like and rope tension has been applied to suppress unintended rollback. However, according to the second embodiment, rollback can be detected and suppressed using only captured images.

[0036] Furthermore, in the past, because it was dangerous for the car to move when the car door was open, sensors or the like were used to detect the movement of the car. However, according to the second embodiment, by constantly detecting the start of movement, unintended movement of the car can be detected.

[0037] In addition, it is possible to select and discard the configurations given in the above embodiment, or to change them to other configurations as appropriate, without departing from the spirit of the present invention. [Explanation of symbols]

[0038] 1 Wire rope inspection equipment 2. Lighting equipment 3. Imaging Equipment 4 Processing Equipment 41 Image input unit 42 Luminance difference calculation section 43 Rope position detector 44 Rollback calculation unit 5 Wire Rope

Claims

1. an imaging unit that continuously images the wire rope while running the wire rope in accordance with a running command; a brightness difference calculation unit that obtains a brightness of a rope area in the captured image by the imaging unit and calculates a time when the wire rope starts to move and a time when the wire rope stops based on a change in brightness over time; a rope calculation unit that calculates a rope position of the wire rope based on a start time and a stop time of the wire rope and a speed profile that is preset by the travel command; Equipped with A wire rope inspection device.

2. an imaging unit that continuously images the wire rope while running the wire rope in accordance with a running command; a brightness difference calculation unit that obtains a brightness of a rope area in the captured image by the imaging unit and calculates a time when the wire rope starts to move and a time when the wire rope stops based on a change in brightness over time; a rollback calculation unit that detects rollback, which is travel in a direction opposite to the travel direction instructed by the travel command, by calculating a travel direction and a movement amount of the wire rope when the start of movement of the wire rope is detected by the brightness difference calculation unit; a rope calculation unit that calculates a position of the wire rope based on a start time and a stop time of the wire rope and a speed profile that is preset by the travel command; Equipped with A wire rope inspection device.

3. Continuously photographing the wire rope while running the wire rope in accordance with a running command; By taking the continuous photographs, a brightness of a rope area in the photographed images is obtained, and a time when the wire rope starts to move and a time when the wire rope stops are calculated based on a change in brightness over time. Calculating a rope position of the wire rope based on a start time and a stop time of the wire rope and a speed profile preset in the travel command; A wire rope inspection method comprising:

Images