Method, controller, positioning system, and computer program for determining a position of an elevator car, elevator, and computer-readable medium

Abstract

A method for determining a position of an elevator car (12) of an elevator (10) is described. The elevator (10) comprising the elevator car (12) for carrying one or more loads and at least one traction medium (14, 16), with the traction medium (14, 16) carrying the elevator car (12). The traction medium (14, 16) comprises at least one load strand (52) extending in a longitudinal direction and being configured for holding the elevator car (12) and at least one fibre optic cable (54, 56) coupled to the load strand (52) and extending parallel to the load strand (52). The method comprises: sending an activation signal to a light source (27, 29) optically coupled to the fibre optic cable (54, 56) of the traction medium (14, 16), wherein the activation signal and the light source (27, 29) are configured such that the light source (27, 29) feeds at least one optical signal into the fibre optic cable (54, 56) upon receiving the activation signal; receiving a measurement signal from a light sensor (28, 30) optically coupled to the fibre optic cable (54, 56) of the traction medium (14, 16), wherein the measurement signal is representative for a reflection of the optical signal within the fibre optic cable (54, 56); and determining the position of the elevator car (12) depending on the measurement signal.

Description

[0001] Method, controller, positioning system, and computer program for determining a position of an elevator car, elevator, and computer-readable medium

[0002] The technology described herein generally relates to a method, a controller, a positioning system, and a computer program for determining a position of an elevator car. The technology described herein further relates to an elevator comprising the positioning system, and to a computer-readable medium on which the computer program is stored.

[0003] An elevator may be used fortransporting a load, e.g. comprising one or more persons and / or goods, within a building from one floor of the building to another floor of the building. To this end, the elevator may comprise an elevator car for accommodating the load and an elevator shaft in which the elevator car may be moved from one of the floors to another one of the floors. The elevator shaft may at least in part extend in vertical direction such that the elevator car may be moved vertically within the elevator shaft. The elevator may comprise one or more traction media coupled to the elevator car, wherein the elevator car may be carried by the traction media. The traction media may comprise one or more ropes and / or belts. The elevator may comprise a motor mechanically coupled to the traction media and being configured to move the elevator car within the elevator shaft via the traction media. The elevator may further comprise an elevator control unit for driving the motor.

[0004] WO 2022 / 228662 Al describes an elevator having a counterweight coupled to the elevator car by a traction medium and a counterweight brake device coupled to the counterweight. The traction medium comprises a fibre optic cable for transferring data from the counterweight brake device to the elevator car. The data may be used for analysing whether the counterweight brake has to be activated or not.

[0005] JP 3896764 B2 describes an elevator having a traction medium. The traction medium comprises a fibre optic cable for determing the aging or wear of the traction medium. For determing the wear of the traction medium the whiting of the fibre optic calbe is measured.

[0006] In order to provide a comfortable and quick transport of the load via the elevator car, it is advantageous to know a current position of the elevator car within the elevator shaft. There are already several methods and corresponding systems known for determining the position of the car within the elevator shaft, e.g. by one or more sensors arranged at the floors, coupled to the elevator control unit, and being configured for detecting an arrival of the elevator car in the corresponding floor. However, sometimes an altemativ approach for determining the position of the car may be helpful, e.g. to provide a backup solution for another system for determining the position of the car, to verify a position determined by the other system, and / or to determine the position of the car more accurately, e.g. between two of the floors.

[0007] Further, it is known to analyze a fibre optic cable with respect to several faults of the fibre optic cable. For example, it is known to send an optical signal through the fibre optic cable, to detect a reflection of the optical signal within the fibre optic cable and to deduct from this measurement which faults the fibre optic cable has. Such faults may be splice- or connection losses, micro-bendings, macro-bendings, etc. For example, an Optical Time-Domain Reflectometer (OTDR) is an optoelectronic instrument used to characterize a fibre optic cable with respect to any faults. It is the optical equivalent of an electronic time domain reflectometer which measures the impedance of the cable or transmission line under test. An OTDR injects a series of optical signal pulses into the fibre optic cable under test and extracts, from the same end of the fibre optic cable, light that is scattered (Rayleigh backscatter) or reflected back from points along the fibre optic cable. The scattered or reflected light that is gathered back is used to characterize the fibre optic cable. The strength of the return pulses is measured and integrated as a function of time, and may be plotted as a function of the length of the fiber. For example, US 9,341,543 B2 or US 8,576,389 B2 each describe an approach for using OTDR for analysing the properties of a fibre optic cable. Another document focusing more on the detection of micro- and macro-bedings was published as a white paper (Ver. 1.0 02 / 2011 VW / DW) from the company “AFU Hyperscale” and may be obtained from the website of AFU Hyperscale (www.aflhyperscale.com / resources / white-papers / ).

[0008] Another approach to use reflections of optical signals in fibre optic cables to determine the shape of the fibre optic cables is described in a document published by the NASA in May 30, 2023, i.e. “Highly Accurate Position Detection and Shape Sensing with Fiber Optics (UAR-TOPS-79)” (obtainable from https: / / technology.nasa.gov / patent / UAR- TOPS-79). In this document, three optical fibres are embedded in one cable and reflections of optical signals within the optical fibres are used to determine a three- dimensional shape of the cable.

[0009] There may be a need for a method, a controller, a positioning system, and / or a computer program for determining a position of an elevator car of an elevator, which may contribute to provide an alternative, a backup solution, a verification, and / or a very accurate determination of the position of the elevator car. Further, there may be a need for the elevator comprising the positioning system and / or for a computer-readable medium on which the computer program is stored.

[0010] Such need may be met by the subject-matter of the independent claims. Advantageous embodiments are defined in the dependent claims as well as in the following specification and the associated figures.

[0011] According to an aspect of the technology described herein a method for determining a position of an elevator car of an elevator is proposed. The elevator comprises the elevator car for carrying a load and at least one traction medium. The traction medium carries the elevator car. The traction medium comprises at least one load strand extending in a longitudinal direction and being configured for holding the elevator car, and at least one fibre optic cable coupled to the load strand and extending parallel to the load strand. The method comprises: sending an activation signal to a light source optically coupled to the fibre optic cable of the traction medium, wherein the activation signal and the light source are configured such that the light source feeds at least one optical signal into the fibre optic cable upon receiving the activation signal; receiving a measurement signal from a light sensor optically coupled to the fibre optic cable of the traction medium, wherein the measurement signal is representative for a reflection of the optical signal within the fibre optic cable; and determining the position of the elevator car from the measurement signal.

[0012] According to another aspect of the technology described herein a controller for determining the position of the elevator car of the elevator is proposed. The elevator comprises the elevator car for carrying the load and at least the traction medium, with the traction medium carrying the elevator car and comprising at least one load strand extending in the longitudinal direction and being configured for holding the elevator car and at least the fibre optic cable coupled to the load strand and extending parallel to the load strand. The controller comprises: a memory for storing one or more measured values; and a processor being configured for carrying out and / or controlling the method in accordance with one of the preceding claims based on the measured values.

[0013] According to another aspect of the technology described herein a positioning system for determining the position of the elevator car for the elevator is proposed. The positioning system comprises: the at least one fibre optic cable of the traction medium of the elevator, with the traction medium carrying the elevator car and comprising the at least one load strand coupled to the fibre optic cable, with the load strand extending in the longitudinal direction and being configured for holding the elevator car and with the fibre optic cable at least partly extending parallel to the load strand; a light source optically coupled to the fibre optic cable such that an optical signal emitted from the light source is fed into the fibre optic cable; a light sensor optically coupled to the fibre optic cable such that at least a part of a reflection of the optical signal within the fibre optic cable is received by the light sensor; and the controller as described above and in the following being communicatively coupled to the light source and the light sensor.

[0014] According to another aspect of the technology described herein the elevator is proposed. The elevator comprises: the positioning system as described above and in the following; the elevator car for carrying the load; the traction medium carrying the elevator car; and at least one motor being mechanically coupled to the traction medium and being configured for moving the elevator car via the traction medium.

[0015] According to another aspect of the technology described herein a computer program for determining the position of the elevator car of the elevator is proposed. The computer program comprises computer-readable instructions which, upon being executed by the processor of the controller as described above and in the following, instruct the controller to at least one of executing and controlling the method for determining the position of the elevator car of the elevator, as described above and in the following.

[0016] According to another aspect of the technology described a computer-readable medium on which the computer program as described above and in the following is stored. The traction medium may extend in the longitudinal direction from one end of the traction medium to another end of the traction medium. The load strand may also extend in the longitudinal direction from the one end of the traction medium to the other end of the traction medium. The load strand may comprise one or more ropes or belts. The fibre optic cable may also extend in the longitudinal direction from the one end of the traction medium to the other end of the traction medium, or the fibre optic cable may extend away from the load strand at one or two positions of the traction medium, e.g. in order to provide a feed-in position for feeding the optical signal into the fibre optic cable or, respectively, to provide a feed-out position for coupling out the reflection of the opticals signal from the fibre optic cable.

[0017] A position and form of the traction medium and as such of the fibre optic cable depends on the position of the elevator car. The reflection of the optical signal depends on the position and form of the fibre optic cable. Therefore, the reflection of the optical signal is representative for the position of the car. Therefore, the position of the car can be determined from the reflection of the optical signal. For example, a Optical Time Domain Reflectometer, OTDR, may be used to analyse the reflection of the optical signal from the measurement signal. From this analysis, the position and form of the fibre optic cable and as such of the traction medium may be determined. Then, the position of the elevator car may be determined from the position and form of the traction medium. Alternatively, an artificial intelligence or machine learning algorithm may be trained to determine the position of the car depending on the reflection of the optical signal. For example, a training data set may be prepared by moving the elevator car to different positions, by recording these positions, by detecting the corresponding reflections, and by recording the corresponding reflection values. Then, the artificial intelligence or, respectively, machine learning algorithm may be trained with the data being based on the reflection values.

[0018] That the processor is configured for carrying out the method may mean that the controller is configured for carrying out the method. A computer program corresponding to the method may also be stored on the memory in addition to the measurement values. The computer program may be the computer program described above and in the following.

[0019] As mentioned above, the fibre optic cable may comprise a feed-in position at which an optical signal may be fed into the fibre optic cable. The light source and / or the light sensor may be optically coupled to the fibre optic cable at the feed-in position of the fibre optic cable. The feed-in position of the fibre optic cable may be provided at one front face of the fibre optic cable.

[0020] According to an embodiment, the elevator comprises at least one pulley over which the traction medium is bent such that the traction medium comprises a bend at least partly around the pulley, and the method further comprises: determining a position of the bend of the traction medium along the traction medium depending on the measurement signal; and determining the position of the elevator car depending on the position of the bend. The position of the pulley is generally known. A distance from the feed-in position to the pulley and thereby to the bend depends on the position of the elevator car. The bend may be a portion of the traction medium and of the fibre optic cable at which these components have a non-straight, i.e. curved, extension geometry. The reflection of the optical signal is representative for the distance from the feed-in position to the bend. Particularly, reflection characteristics of the fibre optic cable may depend on a bending condition, i.e. a bent portion of the fibre optic cable may have other reflection characteristics than a straight or less bent portion. Therefore, the reflection of the optical signal is representative for the position of the elevator car. For example, OTDR may be used to detect the position of the bend depending on the reflection. Then, the output of the OTDR may be used to determine the position of the elevator car.

[0021] According to an embodiment, the position of the bend of the traction medium along the traction medium is determined depending on the measurement signal by determining a duration from feeding the optical signal into the fibre optic cable at a predetermined feedin position of the fibre optic cable to detecting the reflection of the optical signal at a predetermined detection position of the fibre optic cable, and by determining the position of the bend depending on the duration. The farer away the bend is from the feed-in position, the longer is the runtime of the optical signal until it is detected and the longer is the duration. The optical signal fed into the fibre optic cable may be modulated and / or pulsed in order to be able to determine the runtime of the optical signal from leaving the light source to being detected by the light sensor. The OTDR may output the runtime which may be used to determine the duration. The OTDR may also be configured to differentiate between the bend and other influences of the optical signal, e.g. because of one or more smaller defects of the fibre optic cable or because of a reflection of the optical signal at another end of the fibre optic cable. The detection position may correspond to the feed-in position at which the optical signal is coupled into the fibre optic cable.

[0022] According to an embodiment, the elevator comprises the at least one pulley over which the traction medium is bent such that the traction medium comprises the bend and the controller is configured for determining the position of the bend from the reflection of the optical signal and the position of the car from the position of the bend.

[0023] According to an embodiment, the traction medium comprises a jacket surrounding the load strand and the fibre optic cable at least in a direction perpendicular to the longitudinal direction. For example, the load strand and the fibre optic cable may be embedded within the jacket. The jacket may comprise or may be made of plastic. The jacket may couple the load strand to the fibre optic cable. In other words, the load strand and the fibre optic cable may be fixed to each other via the jacket. Alternatively, the load strand and the fibre optic cable may be attached to each other without the jacket. For example, the load strand and the fibre optic cable may touch each other and / or may be glued to each other.

[0024] According to an embodiment, the fibre optic cable comprises a branch at which the fibre optic cable branches away from the load strand. For example, in case of the load strand and the fibre optic cable being embedded within the jacket, the branch may extend out of the jacket. The branch may be arranged at or close to the longitudinal end of the traction medium. The branch of the fibre optic may be used to couple the fibre optic cable to the light source and / or to the light sensor. The feed-in position may be arranged at an end of the branch, in particular at the corresponding front face of the fibre optic cable. The feedin position at the end of the branch may also be used to detect the reflection of the optical signal.

[0025] According to an embodiment, the elevator comprises an elevator shaft in which the elevator car is arranged such that the elevator car is movable within the elevator shaft in vertical direction by the motor via the traction medium, wherein the position of the elevator car is a vertical position of the elevator car within the elevator shaft. Embodiments of the method described herein may be implemented in hardware, software or a combination thereof. Particularly, the computer program may comprise computer- readable instructions which instruct a processor to execute or control the method steps. The processor may be for example the processor of the controller. The computer program may be provided in any computer-readable language.

[0026] The computer-readable medium may be for example a volatile or non-volatile data memory. For example, the computer readable medium may be a flash memory, a DVD, a CD, a ROM, a RAM, an EPROM or similar devices. Alternatively, the computer readable medium may be part of another computer or server or of a data cloud from which the computer program product may be downloaded for example via a network such as the Internet.

[0027] It shall be noted that possible features, advantages, and / or embodiments of the technology described herein may be described with respect to one of the above aspects only. However, it has to be understood that theses features, advantages, and / or embodiments may be easily transferred to another one of the described aspects. One skilled in the art will recognize that the features, advantages, and / or embodiments may be suitably transferred from one of the aspects to another one of the aspects without departing from the inventive idea of the present invention. In addition, the described features and / or embodiments may be modified, adapted, combined and / or replaced, etc. in order to come to further embodiments of the technology described herein.

[0028] In the following, advantageous embodiments of the technology described herein will be described with reference to the enclosed drawings. However, neither the drawings nor the description shall be interpreted as limiting the technology described herein.

[0029] Fig. 1 shows a side view of an exemplary embodiment of an elevator.

[0030] Fig. 2 shows a cutted side view of an exemplary embodiment of a traction medium of the elevator of figure 1.

[0031] Fig. 3 shows a flow-chart of an exemplary embodiment of a method for determining a position of an elevator car of an elevator. The figures are only schematic and not to scale. Same reference signs refer to same or similar features.

[0032] Fig. 1 shows a side view of an exemplary embodiment of an elevator 10. The elevator comprises a positioning system 15, an elevator car 12 for carrying a load, at least one traction medium, e.g. a first traction medium 14 and a second traction medium 16, carrying the elevator car 12, and at least one motor, e.g. a first motor 22 and a second motor 24, being mechanically coupled to the traction medium 14, 16 and being configured for moving the elevator car 12 via the traction medium 14, 16. In particular, the first motor 22 may be mechanically coupled to the first traction medium 14 and the second motor 24 may be mechanically coupled to the second traction medium 16. The elevator 10 may comprise an elevator control unit (not shown) for driving the motor(s) 22, 24.

[0033] The elevator 10 may further comprise an elevator shaft 11 in which the elevator car 12 is movably arranged, at least one counterweight, e.g. a first counterweight 36 and a second counterweight 38, coupled to the elevator car 12 via the corresponding traction medium 14, 16, and at least one pulley, e.g. a first pulley 18 and a second pulley 20, over which the corresponding traction medium 14, 16 is bent. The elevator shaft 11 may at least in part extend in vertical direction such that the elevator car 12 may be moved vertically within the elevator shaft 11. The elevator car 12 may be moved within the elevator shaft 11 in the vertical direction by the motors 22, 24 via the corresponding traction media 14, 16.

[0034] The elevator 10 may be used for transporting the load, e.g. comprising one or more persons and / or goods, within a building from one floor of the building to another floor of the building (not shown). The elevator 10 comprises the elevator car 12 for accommodating the load and the elevator shaft 11 may extend from one of the floors to another one of the floors.

[0035] The traction media 14, 16 each may comprise one or more ropes and / or belts. The first traction medium 14 may extend from the first counterweight 36 around the first pulley 18 to the elevator car 12. The first traction medium 14 may be mechanically coupled to the elevator car 12 at a first fixation point 40 at the elevator car 12. So, a longitudinal end of the first traction medium 14 may be coupled to the elevator car 12 at the first fixation point 40. Another longitudinal end of the first traction medium 14 may be coupled to the first counterweight 36. The first traction medium 14 comprises a first bend 60 at the first pulley 18. The position of the first pulley 18 is fixed, but the position of the bend 60 along the first traction medium 14, in other words with respect to the first traction medium 14, depends on a current position, in particular a current vertical position, of the elevator car 12.

[0036] The second traction medium 16 may extend from the second counterweight 38 around the second pulley 20 to the elevator car 12. The second traction medium 16 may be mechanically coupled to the elevator car 12 at a second fixation point 42 at the elevator car 12. So, a longitudinal end of the second traction medium 16 may be coupled to the elevator car 12 at the second fixation point 42. Another longitudinal end of the first traction medium 16 may be coupled to the second counterweight 38. The second traction medium 16 comprises a second bend 62 at the second pulley 20. The position of the second pulley 20 is fixed, but the position of the bend 62 along the first traction medium 16, in other words with respect to the second traction medium 16, depends on the current position, in particular the current vertical position, of the elevator car 12.

[0037] When the elevator car 12 is lowered within the elevator shaft 11 via the traction media 14, 16 by the motors 22, 24, the elevator car 12 moves away from the pulleys 18, 20, the counterweights 36, 38 come closer to the corresponding pulleys 18, 20, and the bends 60, 62 come correspondingly closer to their longitudinal ends coupled to the corresponding counterweights 36, 38. When the elevator car 12 is lifted via the traction media 14, 16 by the motors 22, 24, the elevator car 12 comes closer to the pulleys 18, 20, the counterweights 36, 38 move away from the corresponding pulleys 18, 20, and the bends 60, 62 move correspondingly away from the longitudinal ends of the corresponding traction medium 14, 16 coupled to the corresponding counterweights 36, 38.

[0038] The traction media 14, 16 each are configured for carrying the elevator car 12. The traction media 14, 16 each comprise at least one load strand 52 (see figure 2) extending in the longitudinal direction and being configured for holding the elevator car 12 and at least one fibre optic cable 54, 56 coupled to the corresponding load strand 52 and extending parallel to the load strand 52. In particular, the first traction medium 14 comprises a first fibre optic cable 54 and the second traction medium 16 comprises a second fibre optic cable 56.

[0039] The fibre optic cables 54, 56 each may comprise at least one branch 44, 46 at which the corresponding fibre optic cable 54, 56 branches away from the corresponding load strand 52. In particular, the first fibre optic cable 54 may comprise two first branches 44 at which the first fibre optic cable 54 branches away from the load strand 52 of the first traction medium 14, and the second fibre optic cable 56 may comprise two second branches 46 at which the second fibre optic cable 56 branches away from the load strand 52 of the second traction medium 16. The branches 44, 46 each may be arranged at or close to the longitudinal ends of the corresponding traction medium 14, 16. For example, one of the first branches 44 may be arranged close to the longitudinal end of the first traction medium 14 which is coupled to the first counterweight 36 and the other one of the first branches 44 may be arranged close to the elevator car 12, in particular close to the first fixation point 40. In this context it has to be mentioned that the figure 1 is not to scale and in the reality a length-ratio of a first length of the traction media 14, 16 from the bottom of the elevator car 12 to the top of the elevator car 12 to a second length of the traction media 14, 16 from the top of the elevator car 12 to the corresponding counterweight 36, 38 is much smaller than depicted in figure 1 such that in the reality and referred to the real whole length of the traction media 14, 16 the branches 44, 46 at the top of the elevator car 12 may be regarded as being (relatively) close to the corresponding fixation points 40, 42 at the bottom of the elevator car 12.

[0040] The positioning system 15 is configured for determining the current position of the elevator car 12. The positioning system 15 comprises the fibre optic cable 54, 56 of at least one of the traction media 14, 16, at least one light source, e.g. a first light sources 27 and a second light source 29, and at least one light sensor, e.g. a first light sensor 28 and a second light sensor 30, and a controller 26 for determining the current position of the elevator car 12. Each of the light sources 27, 29 may comprise one or more LEDs or OLEDs, for example. Each of the light sensors 28, 30 may comprise one or more photodetectors or a small camera comprising several light sensitive elements. The first fibre optic cable 54 may be optically coupled to the first light source 27 and to the first light sensor 28. The first light source 27 and the first light sensor 28 may be arranged in the same sensor housing. The second fibre optic cable 56 may be optically coupled to the second light source 29 and to the second light sensor 30. The second light source 29 and the second light sensor 30 may be arranged in the same sensor housing. The light sources 27, 29 may be optically coupled to the corresponding fibre optic cable 54, 56 such that optical signals emitted from the light sources 27, 29 may be fed into the corresponding fibre optic cable 54, 56. The light sensors 28, 30 may be optically coupled to the corresponding fibre optic cable 54, 56 such that at least parts of the reflections of the optical signals within the fibre optic cables 54, 56 may be received by the light sensors 28, 30. For example, the branches 44, 46 of the fibre optic cables 54, 56 may be used to couple the fibre optic cables 54, 56 to the corresponding light sources 27, 29 and / or to the corresponding light sensors 28, 30.

[0041] Feed-in positions at which the optical signal may be fed into the fibre optic cables 54, 56 may be arranged at the end of the corresponding branches 44, 46, for example at the corresponding front faces of the corresponding fibre optic cables 54, 56. The feed-in positions may also be used to detect the reflection of the optical signal. At another end of the traction media 14, 16 the fibre optic cables 54, 56 may be optically coupled to corresponding reflectors 32, 34. For example, the first fibre optic cable 54 may be optically coupled to a first reflector 32 and the second fibre optic cable 56 may be optically coupled to a second reflector 34.

[0042] The controller 26 is communicatively coupled to the light sources 27, 29 and the light sensors 28, 30. The controller 26 may be a component of the elevator control unit or may be a separate component communicatively coupled to the elevator control unit. The controller 26 is configured for determining the position of the elevator car 12 of the elevator 10. The controller 26 comprises a memory 23 for storing one or more measured values and a processor 25 being configured for carrying out a method for determining the position of the elevator car 12 based on the measured values, as shortly described in the following and as explained in detail with respect to figure 3. The measured values may be representative of the reflections of the optical signal and may be referred to as reflection values. A position and form of each of the traction media 14, 16 and as such of the fibre optic cables 54, 56 depends on the position of the elevator car 12. The reflection of the optical signal depends on the position and form of the corresponding fibre optic cable 54, 56. Therefore, the reflection of the optical signal is representative for the position of the elevator car 12. Therefore, the position of the elevator car 12 can be determined from the reflection of the optical signal. For example, a Optical Time Domain Reflectometer, OTDR, may be used to analyse the reflection of the optical signal from the measurement signal. The OTDR may be a component of the controller 26. From this analysis, the position and form of the fibre optic cables 54, 56 and as such from the corresponding traction medium 14, 16 may be determined. Then, the position of the elevator car 12 may be determined from the position and form of the traction media 14, 16. Alternatively, an artificial intelligence or machine learning algorithm may be trained to determine the position of the elevator car 12 depending on the reflection of the optical signal. For example, a training data set may be prepared by moving the elevator car 12 to different positions, by recording these positions, by detecting the corresponding reflections, and by recording the corresponding reflection values. Then, the artificial intelligence or, respectively, machine learning algorithm may be trained with the data being based on the reflection values.

[0043] For determining the position of the elevator car 12, the positioning unit 15 may comprise one of the fibre optic cables 54, 56 only, e.g. the first fibre optic cable 54. In this case, the positioning unit may comprise the first light source 27 and the first light sensor 28 only. Providing the second fibre optic cable 56 and correspondingly the second light source 29 and the second light sensor 30 may enable to verify and / or to determine more accurately the position determined via the first fibre optic cable 54, the first light source 27 and the first light sensor 28, and / or may enable to provide a backup system in case of a failure of the first fibre optic cable 54, the first light source 27 and / or the first light sensor 28.

[0044] Fig. 2 shows a cutted side view of an exemplary embodiment of one of the traction media 14, 16 of the elevator 10 of figure 1. The traction medium 14, 16 comprises the load strand 52 and the corresponding fibre optic cable 54, 56. The traction medium 14, 16 may extend in the longitudinal direction from one end of the traction medium 14, 16 to another end of the traction medium 14, 16. The load strand 52 may also extend in the longitudinal direction from the one end of the corresponding traction medium 14, 16 to the other end of the corresponding traction medium 14, 16. The load strand 52 may comprise one or more ropes or belts. The fibre optic cable 54, 56 may also extend in the longitudinal direction from the one end of the traction medium 14, 16 to the other end of the traction medium 14, 16, or the fibre optic cable 54, 56 may extend away from the load strand 52 at one or two positions of the traction medium 14, 16, in particular at the corresponding branches 44, 46, e.g. in order to provide the feed-in position for feeding the optical signal into the fibre optic cable 54, 56 or, respectively, to provide a feed-out position for coupling the reflection of the opticals signal out of the corresponding fibre optic cable 54, 56.

[0045] The traction medium 14, 16 may comprise a jacket 50 surrounding the load strand 52 and a corresponding one of the fibre optic cables 54, 56 at least in a direction perpendicular to the longitudinal direction. For example, the load strand 52 and the corresponding fibre optic cable 54, 56 may be embedded within the jacket 50. The jacket 50 may comprise or may be made of plastic. The jacket 50 may couple the load strand 52 to the corresponding fibre optic cable 54, 56. In other words, the load strand 52 and the corresponding fibre optic cable 54, 56 may be fixed to each other via the jacket 50. Alternatively, the load strand 52 and the corresponding fibre optic cable 54, 56 may be attached to each other without the jacket 50. For example, the load strand 52 and the corresponding fibre optic cable 54, 56 may touch each other and / or may be glued to each other. In case of the load strand 52 and the corresponding fibre optic cable 54, 56 being embedded within the jacket 50, the branches 44, 46 may extend out of the corresponding jacket 50.

[0046] Fig. 3 shows a flow-chart of an exemplary embodiment of the method for determining the position of the elevator car 12 of the elevator 10, in particular the vertical position of the elevator car 12 within the elevator shaft 11.

[0047] The position of the pulleys 18, 20 is generally known. As explained above, a distance from the feed-in positions to the pulleys and thereby to the bends 60, 62 depends on the position of the elevator car 12. The reflection of the optical signal is representative for this distance from the feed-in positions to the corresponding bend 60, 62. Therefore, the reflection of the optical signal is representative for the position of the elevator car 12. In a step S2, an activation signal may be sent to the first and / or second light source 27, 29 optically coupled to the first and / or, respectively, second fibre optic cable 54, 56 of the corresponding traction medium 14, 16. The activation signal and the corresponding light source 27, 29 may be configured such that the corresponding light source 27, 29 feeds at least one optical signal into the corresponding fibre optic cable 54, 56 upon receiving the activation signal.

[0048] In a step S4, a measurement signal from the first and / or second light sensor 28, 30 optically coupled to the corresponding fibre optic cable 54, 56 may be received. The measurement signal may be representative for the reflection of the corresponding optical signal within the corresponding fibre optic cable 54, 56.

[0049] In a step S6, the position of the elevator car 12 may be determined depending on the received measurement signal.

[0050] For determining the position of the elevator car 12 in step S6, steps S8 and S10 may be carried out.

[0051] In step S8, a position of at least one of the bends 60, 62 of the corresponding traction medium 14, 16 along the corresponding traction medium 60, 62 may be determined depending on the measurement signal. The positions of the bends 60, 62 of the traction media 14, 16 along the corresponding traction medium 14, 16 may be determined depending on the corresponding measurement signal by determining durations from feeding the optical signals into the corresponding fibre optic cables 54, 56 at the corresponding feed-in positions to detecting the reflection of the optical signal at the detection position, e.g. the feed-in position, and by determining the position of the bends 60, 62 depending on the corresponding duration. The farer away the bends 60, 62 are from the corresponding feed-in positions, the longer is the runtime of the optical signal until it is detected and the longer is the duration. The optical signals fed into the fibre optic cables 54, 56 may be modulated and / or pulsed in order to be able to determine the runtime of the optical signal from leaving the light sources 27, 29 to being detected by the corresponding light sensor 28, 30. For example, OTDR may be used to detect the position of the bends 60, 62 depending on the reflection. The OTDR may output the runtime which may be used to determine the duration. The OTDR may also be configured to differentiate between the bends 60, 62 and other influences of the optical signal, e.g. because of one or more smaller defects of the fibre optic cables 54, 56 or because of a reflection of the optical signal at the other end of the corresponding fibre optic cable 54, 56, e.g. at the corresponding reflector 32, 34.

[0052] In step S10, the position of the elevator car 12 may be determined depending on the position of at least one of the bends 60, 62. For example, the output of the OTDR may be used to determine the position of the elevator car 12.

[0053] Embodiments of the method described herein may be implemented in hardware, software or a combination thereof. Particularly, the computer program may comprise computer- readable instructions which instruct a processor to execute or control the method steps. The processor may be for example the processor 25 of the controller 26. The computer program may be provided in any computer-readable language.

[0054] The controller 26, in particular the processor 25, may be configured for carrying out the above method. A computer program corresponding to the method may be stored on the memory 23 in addition to the measurement values. The computer program may be configured for determining the position of the elevator car 12 of the elevator 10. The computer program comprises computer-readable instructions which, upon being executed by the processor 25 of the controller 26, instruct the controller 26 to at least one of executing and controlling the method for determining the position of the elevator car 12 of the elevator 10.

[0055] The computer program may be stored on a computer-readable medium. The computer- readable medium may be for example a volatile or non-volatile data memory. For example, the computer readable medium may be a flash memory, a DVD, a CD, a ROM, a RAM, an EPROM or similar devices. Alternatively, the computer-readable medium may be part of another computer or server or of a data cloud from which the computer program product may be downloaded for example via a network such as the Internet. Finally, it should be noted that the term “comprising” does not exclude other elements or steps and the “a” or “an” does not exclude a plurality. Also elements described in association with different embodiments may be combined. It should also be noted that reference signs in the claims should not be construed as limiting the scope of the claims.

[0056] List of reference signs

[0057] 10 elevator

[0058] 11 elevator shaft

[0059] 12 elevator car

[0060] 15 positioning system

[0061] 14 first traction medium

[0062] 16 second traction medium

[0063] 18 first pulley

[0064] 20 second pulley

[0065] 22 first motor

[0066] 23 memory

[0067] 24 second motor

[0068] 25 processor

[0069] 26 controller

[0070] 27 first light source

[0071] 28 first light sensor

[0072] 29 second light source

[0073] 30 second light sensor

[0074] 31 feed-in position

[0075] 32 first reflector

[0076] 34 second reflector

[0077] 36 first counterweight

[0078] 38 second counterweight

[0079] 40 first fixation point

[0080] 42 second fixation point

[0081] 44 first branch

[0082] 46 second branch

[0083] 50 jacket

[0084] 52 load strand

[0085] 54 first fibre optic cable

[0086] 56 second fibre optic cable

[0087] 60 first bend

[0088] 62 second bend

Claims

Claims:

1. Method for determining a position of an elevator car (12) of an elevator (10), the elevator (10) comprising the elevator car (12) for carrying a load and at least one traction medium (14, 16), with the traction medium (14, 16) carrying the elevator car (12) and comprising at least one load strand (52) extending in a longitudinal direction and being configured for holding the elevator car (12) and at least one fibre optic cable (54, 56) coupled to the load strand (52) and extending parallel to the load strand (52), the method comprising: sending an activation signal to a light source (27, 29) optically coupled to the fibre optic cable (54, 56) of the traction medium (14, 16), wherein the activation signal and the light source (27, 29) are configured such that the light source (27, 29) feeds at least one optical signal into the fibre optic cable (54, 56) upon receiving the activation signal; receiving a measurement signal from a light sensor (28, 30) optically coupled to the fibre optic cable (54, 56) of the traction medium (14, 16), wherein the measurement signal is representative for a reflection of the optical signal within the fibre optic cable (54, 56); and determining the position of the elevator car (12) from the measurement signal.

2. Method in accordance with claim 1, wherein the elevator (10) comprises at least one pulley (18, 20) over which the traction medium (14, 16) is bent such that the traction medium (14, 16) comprises a bend (60, 62) at least partly around the pulley (18, 20), the method further comprising: determining a position of the bend (60, 62) of the traction medium (14, 16) along the traction medium (14, 16) depending on the measurement signal; and determining the position of the elevator car (12) depending on the position of the bend (60, 62).

3. Method in accordance with one of the preceding claims, wherein the position of the bend (60, 62) of the traction medium (14, 16) along the traction medium (14, 16) is determined depending on the measurement signal by determining a duration from feeding the optical signal into the fibre optic cable (54, 56) at a predetermined feed-in position (31) of the fibre optic cable (54, 56) todetecting the reflection of the optical signal at a predetermined detection position of the fibre optic cable (54, 56) and by determining the position of the bend (60, 62) depending on the duration.

4. Controller (26) for determining a position of an elevator car (12) of an elevator (10), the elevator (10) comprising the elevator car (12) for carrying a load and at least one traction medium (14, 16), with the traction medium (14, 16) carrying the elevator car (12) and comprising at least one load strand (52) extending in a longitudinal direction and being configured for holding the elevator car (12) and at least one fibre optic cable (54, 56) coupled to the load strand (52) and extending parallel to the load strand (52), the controller (26) comprising: a memory (23) for storing one or more measured values; and a processor (25) being configured for at least one of carrying out and controlling the method in accordance with one of the preceding claims based on the measured values.

5. Positioning system (15) for determining a position of an elevator car (12) for an elevator (10), the positioning system (15) comprising: at least one fibre optic cable (54, 56) of a traction medium (14, 16) of the elevator (10), with the traction medium (14, 16) carrying the elevator car (12) and comprising a at least one load strand (52) coupled to the fibre optic cable (54, 56), with the load strand (52) extending in a longitudinal direction and being configured for holding the elevator car (12) and with the fibre optic cable (54, 56) at least partly extending parallel to the load strand (52); a light source (27, 29) optically coupled to the fibre optic cable (54, 56) such that an optical signal emitted from the light source (27, 29) is fed into the fibre optic cable (54, 56); a light sensor (28, 30) optically coupled to the fibre optic cable (54, 56) such that at least a part of a reflection of the optical signal within the fibre optic cable (54, 56) is received by the light sensor (28, 30); and a controller (26) in accordance with claim 4 communicatively coupled to the light source (27, 29) and the light sensor (28, 30).

6. Elevator (10), comprising: a positioning system (15) in accordance with claim 5;the elevator car (12) for carrying a load; the traction medium (14, 16) carrying the elevator car (12); and at least one motor (22, 24) being mechanically coupled to the traction medium (14, 16) and being configured for moving the elevator car (12) via the traction medium (14, 16).

7. Elevator (10) in accordance with claim 6, comprising: at least one pulley (18, 20) over which the traction medium (14, 16) is bent such that the traction medium (14, 16) comprises a bend (60, 62), wherein the controller (26) is configured for carrying out the method in accordance with one of claims 2 or 3.

8. Elevator (10) in accordance with one of claims 5 to 7, wherein the traction medium (14, 16) comprises a jacket (60) surrounding the load strand (52) and the fibre optic cable (54, 56) at least in a direction perpendicular to the longitudinal direction.

9. Elevator (10) in accordance with one of claims 5 to 8, wherein the fibre optic cable (54, 56) comprises a branch (44, 46) at which the fibre optic cable (14, 16) branches away from the load strand (52).

10. Elevator (10) in accordance with one of claims 5 to 9, comprising: an elevator shaft (11) in which the elevator car (12) is arranged such that the elevator car (12) is movable within the elevator shaft (11) in vertical direction by the motor (22, 24) via the traction medium (14, 16), wherein the position of the elevator car (12) is a vertical position of the elevator car (12) within the elevator shaft (11).

11. Computer program for determining a position of an elevator car ( 12) of an elevator (10), the computer program comprising computer-readable instructions which, upon being executed by a processor (25) of a controller (26) in accordance with claim 4, instruct the controller (26) to at least one of executing and controlling a method according to one of claims 1 to 3.

12. Computer-readable medium on which a computer program according to claim11 is stored.

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