Patent Application
20220089408
The invention concerns in general the technical field of elevators. More particularly, the invention concerns rope monitoring solution for elevator systems.
Elevator safety is one of the most important matters to ensure. The elevator systems comprise ropes, such as suspension ropes, compensation ropes and over-speed governor ropes, which are wearing parts having an estimated life-time and for this reason a condition of the ropes needs to be monitored for ensuring safe use of the elevator system and life-time predictability in question.
Typically, the ropes used in the elevator solutions now-a-days are stranded steel wire ropes. The ropes may be affected by corrosion, chemical attack as well as mechanical attack which all may cause damages to the ropes. The challenge in traditional ways of monitoring the condition of the elevator ropes is to decide so-called discard criteria for replacing a damaged rope with a new one. Especially, the decision-making, and especially an evaluation of the rope condition, has been time-consuming and inaccurate with the traditional methods, because it is based on a visible detection of diameter reduction and broken wires within the rope. Additionally, a tolerance for rope permanent elongation may be monitored.
In a document WO 2018/101296 A1 it is described a solution for monitoring an elevator rope. The solution is based on using a plurality of cameras for imaging an entire circumference of a traveling elevator rope and the images taken with the cameras are brought to image processing means for detecting an abnormality in the elevator rope by analyzing the entire circumferential image created from a plurality of images taken with the plurality of cameras. The solution also comprises speed/position detecting device for providing information to be associated with the images in order to combine the plurality of images in an appropriate manner. However, the solution as introduced in the document is problematic in a sense that it is slow to use since combining the images and analyzing the combined image is time consuming as well as costly due to complex structure of the solution.
Hence, there is need to introduce alternative solutions which mitigate at least in part drawbacks of the existing solutions and allow condition monitoring of elevator ropes in an efficient manner.
The following presents a simplified summary in order to provide basic understanding of some aspects of various invention embodiments. The summary is not an extensive overview of the invention. It is neither intended to identify key or critical elements of the invention nor to delineate the scope of the invention. The following summary merely presents some concepts of the invention in a simplified form as a prelude to a more detailed description of exemplifying embodiments of the invention.
An object of the invention is to present an elevator rope monitoring device, a method, a computer program product and a system for monitoring an elevator rope.
The objects of the invention are reached by an elevator rope monitoring device, a method, a computer program product and a system for monitoring an elevator rope as defined by the respective independent claims.
According to a first aspect, an elevator rope monitoring device is provided, the elevator rope monitoring device comprising: at least one source of electromagnetic radiation for emitting a radiation beam; at least one sensor for receiving at least part of an emitted radiation beam; a control unit for detecting an abnormality of an elevator rope arranged to travel between the at least one source of electromagnetic radiation and the at least one sensor by analyzing measurement data received from the at least one sensor.
For example, the at least one source of electromagnetic radiation may comprise at least one lens for collimating the radiation.
The at least one source of electromagnetic radiation and the at least one lens may be mutually positioned so that the at least one source of electromagnetic radiation is positioned into a focal point of the at least one lens.
The at least one source of electromagnetic radiation may further comprise at least one radiation aperture for blocking at least a portion of the radiation for generating a linear radiation beam.
Further, the at least one source of electromagnetic radiation may further comprise a radiation window for emitting the radiation beam towards the at least one sensor from the at least one source of electromagnetic radiation.
The at least one source of electromagnetic radiation may also comprise a controllable protection cover for protecting the radiation window from dirt, the controllable protection cover is arranged on a surface of the radiation window facing the at least one sensor.
Alternatively or in addition, the at least one source of electromagnetic radiation may comprise a protection cover arranged on a surface of the radiation window facing the at least one sensor, the protection cover is implemented with a number of detachable plastic protecting films stacked on top of each other on the radiation window.
Moreover, the at least one sensor may be a linear photosensitive array detector.
Still further, the control unit may be arranged to perform an analysis by: generating a representation of the elevator rope as a function of a lengthwise position of the elevator rope.
The control unit may also be arranged to detect deviation between the data received from the at least one sensor and a comparison data in the analysis. The comparison data may e.g. comprise at least one of the following: a comparison value for a width of the elevator rope; a comparison value for a data representing an edge of the elevator rope; a comparison value for a data representing a loose strand of the elevator rope; a comparison value for a data representing a wire-cut of the elevator rope (150).
Generally speaking, the at least one source of electromagnetic radiation may be arranged to generate a laser light. The at least one source of electromagnetic radiation may e.g. comprise at least one laser diode for generating the laser light.
According to a second aspect, a method for monitoring an elevator rope is provided, the method comprising: generating, by a control unit of an elevator rope monitoring device, a control signal to at least one source of electromagnetic radiation for emitting a radiation beam; receiving, by the control unit of the elevator rope monitoring device, a measurement data from at least one sensor receiving at least part of an emitted radiation beam; detecting, by the control unit of the elevator rope monitoring device, an abnormality of an elevator rope arranged to travel between the at least one source of electromagnetic radiation and the at least one sensor by analyzing data received from the at least one sensor.
Moreover, the analysis comprises: generating a representation of the elevator rope as a function of a lengthwise position of the elevator rope.
The control unit may be arranged to detect deviation between the representation of the elevator rope generated from the measurement data received from the at least one sensor and a comparison data. The comparison data may comprise at least one of the following: a comparison value for a width of the elevator rope; a comparison value for a data representing an edge of the elevator rope; a comparison value for a data representing a loose strand of the elevator rope; a comparison value for a data representing a wire-cut of the elevator rope (150).
According to a third aspect, a computer program product for monitoring an elevator rope is provided which computer program product, when executed by at least one processor, cause a control unit of the elevator rope monitoring device to perform the method as described above.
According to a fourth aspect, an elevator system is provided, the elevator system comprising: an elevator rope monitoring device as defined above, and at least one elevator rope arranged to travel between at least one source of electromagnetic radiation of the elevator rope monitoring device and at least one sensor of the elevator rope monitoring device.
The expression “a number of” refers herein to any positive integer starting from one, e.g. to one, two, or three.
The expression “a plurality of” refers herein to any positive integer starting from two, e.g. to two, three, or four.
Various exemplifying and non-limiting embodiments of the invention both as to constructions and to methods of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific exemplifying and non-limiting embodiments when read in connection with the accompanying drawings.
The verbs “to comprise” and “to include” are used in this document as open limitations that neither exclude nor require the existence of unrecited features. The features recited in dependent claims are mutually freely combinable unless otherwise explicitly stated. Furthermore, it is to be understood that the use of “a” or “an”, i.e. a singular form, throughout this document does not exclude a plurality.
The embodiments of the invention are illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings.
The specific examples provided in the description given below should not be construed as limiting the scope and/or the applicability of the appended claims. Lists and groups of examples provided in the description given below are not exhaustive unless otherwise explicitly stated.
Especially in example embodiments in which the electromagnetic radiation is in a range of wavelengths being so-called visible light it may be necessary to protect the radiation window 340 from dirt. In some embodiment a controllable protection cover for protecting the radiation window may be arranged on a surface of the radiation window 340 facing the at least one sensor 120. For example, the protection cover may be equipped with a transport device i.e. an actuator, such as with a solenoid, an electric motor or a servomotor, which may generate power for displacing the protection cover from the radiation window 340 at least in part e.g. in accordance with a control signal generated by the control unit 140. Alternatively or in addition, the protection of the radiation window 340 may be arranged so that there is arranged a number of detachable plastics protecting films stacked on top of each other on the radiation window 340. Hence, the detachable plastic protecting films may be removed, e.g. one at a time, so that dirty outmost layer may be removed by detaching the topmost film, and in that manner the elevator rope monitoring device may be maintained operative. Usually applicable plastic protecting films are transparent especially when the electromagnetic radiation is visible light, but it may be dependent on the applied electromagnetic radiation.
An advantage of using the radiation aperture 330 is that especially in various embodiments in which the electromagnetic radiation is visible light it is preferred to block at least part of the light to end up to the sensor side, because the light falling outside a detection area of the sensor causes degradation in a contrast of an image generated from the data obtainable from the sensor 130. Hence, the radiation aperture 330 as such is not an essential element but may be used in various embodiments for improving a monitoring result of the device.
The source of electromagnetic radiation 110 may be arranged to generate any suitable electromagnetic radiation and the sensor 130 is selected accordingly i.e. the source and the sensor are matched to operate together. According to an example embodiment the electromagnetic radiation may be visible light, such as having a wavelength of about 380 to 740 nanometers. According to an advantageous embodiment the elevator rope monitoring device may be implemented so that the electromagnetic radiation is laser light. The laser light has known advantages, such as coherence, directionality, monochromatic, and high intensity, e.g. with respect to ordinary light, and for this reason it is suitable for measurement applications. Hence, the radiator element 310 may be selected accordingly. For example, the radiator element 310 may be an applicable laser diode, such a single mode laser having an output power of 5 mW. In case of the radiation is laser light the source of electromagnetic radiation 110 may, hence, generate a line laser pattern towards the sensor 130, and any object, such as a rope 150, therebetween.
The elevator rope monitoring device also comprises at least one sensor 130 suitable for detecting the electromagnetic radiation used in the elevator rope monitoring device. Advantageously, the at least one sensor 130 is selected so that a shadow cast by a rope 150 under monitoring fits entirely in a detection area of the sensor 130 in response to a radiation. However, in some embodiments it may be arranged that only one edge of the rope 150 is monitored, or it may be arranged that a shadow of one edge of the rope 150 is detected by one sensor 130 and the shadow of the other edge of the rope 150 is detected by another sensor 130. According to still further example embodiment the sensor 130 may be selected, by size, so that shadows of a plurality of monitored ropes 150 fit in the detection area of the sensor 130 and the analysis of the conditions of the sensors 130 may be arranged separately through signal processing.
An applicable sensor 130 may be a so-called linear photosensitive array which may refer to a sensor comprising photo sensing elements in one row forming, hence, a pixel row. Such a sensor 130 has an advantage that it may be read in a fast way. However, other sensor implementations may also be applied to, such as sensors comprising sensing elements in a wider area than just in one row, such as a matrix sensor. In some implementations, the matrix sensor may be applied in such a way where one line of the matrix of sensor elements is dedicated for laser and a rest of the sensor elements in the matrix are used for capturing a normal photo image on the rope(s).
As discussed, the source of electromagnetic radiation 110 of the elevator rope monitoring device and the sensor 130 of the elevator rope monitoring device are mutually positioned, with respect to each other, so that the at least one elevator rope 150 under monitoring may be arranged to travel between the source 110 and the sensor 130 and the orientation of the rope 150 in the elevator rope monitoring device is such that at least portion of a shadow of the rope 150 projects on the sensor 130, and, hence, a portion of the radiation passes the rope 150 and reaches the sensor 130 directly.
Regarding the reading of data from the sensor it is advantageous to read the pixels simultaneously. The simultaneous reading of the pixels mitigates any impact of a vibration of the rope to the result of the monitored parameter, such as to the rope width, such as a diameter in a context of ropes having circular cross section. This may be important at least in some embodiments, since the ropes are always vibrating in a plane perpendicular to rope longitude axis, which otherwise could destroy an accuracy of the monitoring.
Next, at least some aspects of the present invention are now described by introducing aspects relating to an analysis of data obtained from at least one sensor 130. First, data generated in response to a provision of electromagnetic radiation by a source of electromagnetic radiation 110 may be read out from the sensor 130 i.e. from data storing entities, such as pixels of the sensor. Depending on the implementation the reading of the data from the sensor 130 may be arranged so that the reading of data is performed simultaneously from the sensor 130 and post-processing of the data may e.g. be initiated by analyzing the measurement data so that the analysis is started from the measurement data obtained, i.e. read, from at least one outmost pixel, preferably from both outmost pixels, residing at both ends of the sensor 130 and continuing the analysis e.g. pixel-by-pixel to an inward direction towards a center pixel(s) of the sensor 130. This kind of reading technique may be called as an outside-inside reading. A more preferred implementation in the context of the present invention, however, may be that the processing, or analyzing, of the measurement data obtained from the pixels simultaneously, i.e. at the same instant of time, may be arranged so that the measurement data obtained from center pixel(s) is processed, i.e. analyzed, first and the processing direction is outwards from the center i.e. towards the outmost pixels i.e. outward direction. This corresponds to a phenomenon that a shadow of the elevator rope generates data in the pixels residing in the center of the sensor and by reading outwards one or more edges may be detected. This kind of reading technique may be called as an inside-outside reading. Moreover, it may be arranged that at least some of the pixels are not read at all. For example, since at least one aim of the present invention may be to detect abnormalities in an elevator rope 150 through an establishment of a representation of the elevator rope 150 i.e. from an image representing a shadow of the rope 150 it may not be necessary to read pixels representing a center of the rope 150 because detections with respect to the abnormalities are challenging to make from that data, and an edge area of the rope is more interesting. In this manner, i.e. by selecting a detection area from the sensor 130, it is possible to optimize the data to be read from the sensor 130 and to be analyzed by the control unit 140.
As described, by reading the sensor data, in a row-by-row, and preferably all pixels simultaneously in order to maintain an accuracy, in response to moving of the rope 150 along its travel path, it is possible to generate a representation e.g. as an image representing the elevator rope 150 within an inspected length of the rope 150.
Further data analysis may be selected in accordance with a characteristic under monitoring. At least the following characteristics may be derived from the representation generated from data received from the at least one sensor 130: rope width, rope defect, loose strand of the rope, which either alone or in any combination may provide information for performing a detection of abnormality of the rope 150 under monitoring.
According to an embodiment of the invention the rope width may be determined by detecting a first edge of the rope 150 and a second edge of the rope from the sensor data as described above, and by determining of the width of the rope on the basis of pixels between the two edges, such as based on a number of pixels between the two edges storing data representing a certain color, such as black. For example, a pixel size may be known and based on that information the width may be determined. For the detection of the first and the second edge of the rope 150 rules may be determined and by applying them to the measurement data obtained from the sensor 130 the edges may be found. In response to the determination of the width of the rope, it may be compared to a comparison value defining a preferred width of the elevator rope 130, and a detection of abnormality may be performed if the values deviate from each other more than a comparison value possibly with some tolerance limit.
According to another embodiment of the invention an analysis for detecting an abnormality of the rope may comprise, e.g. in addition to the rope width analysis, may comprise a rope defect analysis. The rope defect analysis may e.g. be arranged to generate a detection if a strand of the rope 150 is extruded among other strand spirals or single wire-cuts are extruded out of strand. An example of such a situation is schematically disclosed in
According to a still further embodiment of the invention an analysis for detecting an abnormality of the rope 150 may comprise, e.g. in addition to the above described analysis, a loose strand and/or wire-cut analysis. The loose strand analysis, i.e. a detection of the loose strand, may comprise a detection of a number of loose strands by performing a Fast Fourier Transform (FFT), such as a short-time Fourier transform, of a measurement time with respect to a rope 150 width data. As the measurement data is represented in a frequency domain through the Fourier transform it is possible to detect frequency components, such as rising lower frequency components, in the frequency spectrogram, which may represent one or more loose strands of the rope 150. For example, the control unit 140 may have access to a comparison value of a loose strand which is compared with value obtainable from the measurement data represented in the frequency domain. In response to a detection of a number of loose strands it may be decided, by applying predetermined rules, if the rope 150 is abnormal or not. For example, the comparison value, i.e. the rule, may define a gradient of the rising lower frequency component and/or an amplitude of it in order to determine if the frequency component in question represents the loose strand in the elevator rope 150 or not. In case one or more rising lower frequency components are identified, the control unit 150 may be arranged to generate an indication on a loose strand in the elevator rope 150, which may be judged to be a defect of the rope 150.
As is derivable from the description herein various embodiments of the invention allow detecting an abnormality of the elevator rope 150. With the present invention it is possible to establish sophisticated solution e.g. by illustrating the elevator rope 150 under monitoring as a function of a position in its length, i.e. lengthwise position of the elevator rope 150. More specifically, outer dimensions of the elevator rope 150, i.e. the edge of the elevator rope 150, may be under interest. This kind of illustration may require that a speed of the elevator rope 150 is known. The speed information may e.g. be derived with motor encoder measurement. On the other hand, if exact measurement position of the elevator rope 150 is not known e.g. from any external reference, also the strand peak/valley variation, as may e.g. be seen from
By applying the above described non-limiting examples of an analysis of the rope 150 it is possible to detect abnormalities in the rope 150. Prior to performing the analysis itself the data obtained from the sensor 130 may be processed so that any interference e.g. originating from background light may be deducted from the data obtained from the sensor during the measurement. The amount of background light may e.g. be determined through a test measurement without performing a radiation with the source of electromagnetic radiation 110. For example, each pixel may detect black to white color between a pixel value 0-255. Hence, such a setup may be arranged that a detection of black pixel is set with pixel values 0-126 and a detection of white pixels is set with pixel values 127-255.
Some aspects of the present invention relate to a method for monitoring an elevator rope 150. A non-limiting example of the method according to an embodiment of the invention is schematically illustrated in
According to various embodiments of the invention the analysis may comprise an operation in which it is generated a representation of the elevator rope 150 as a function of an elevator rope 150 length. In other words, a representation of the elevator rope 150 may be generated along the length of the elevator rope 150 which is moved through the at least one source of electromagnetic radiation 110 and the at least one sensor 120. The analysis, performed by the control unit 140, may be arranged to detect one or more deviations between the representation of the elevator rope 150 generated from the measurement data received from the at least one sensor 120 and a comparison data. The comparison data may comprise at least one of the following: a comparison value for a width of the elevator rope 150; a comparison value for a data representing an edge of the elevator rope 150; a comparison value for a data representing a loose strand of the elevator rope 150; a comparison value for a data representing a wire-cut of the elevator rope 150. The method according to various embodiments of the present invention may comprise further operation as described in the context of the description of the elevator rope monitoring device.
Moreover, some aspects of the present invention may relate to a computer program product for monitoring an elevator rope 150 which, when executed by at least one processor, cause a control unit of the elevator rope monitoring device to perform the method as described. The computer program product may be stored in a non-transitory computer-readable medium, such as an applicable memory unit, accessible to the processor configured to execute the computer program product.
Some further aspects of the invention may relate to an elevator system comprising: an elevator rope monitoring device as described and at least one elevator rope 150 arranged to travel between at least one source of electromagnetic radiation 110 of the elevator rope monitoring device and at least one sensor 120 of the elevator rope monitoring device. Naturally, the elevator system may comprise further elements and entities as e.g. discussed in the description of
The solution according to the present invention enable a condition monitoring of elevator ropes with respect to at least some of the following aspects: a change in width of the rope e.g. caused by non-lubricated rope, a detection of cut wires within the rope, a detection of loose strand, a detection of a strained rope, a detection of slipping rope. The described solution is fast enough to be capable of inspecting the rope during normal usage speed or maintenance drive speed in high enough resolution.
The specific examples provided in the description given above should not be construed as limiting the applicability and/or the interpretation of the appended claims. Lists and groups of examples provided in the description given above are not exhaustive unless otherwise explicitly stated.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/FI2019/050587 | Aug 2019 | US |
| Child | 17542784 | US |
