WO2023203274A1

WO2023203274A1 - Control of travel speed of an elevator car

Info

Publication number: WO2023203274A1
Application number: PCT/FI2022/050261
Authority: WO
Inventors: Matti Mustonen; Mari Zakrzewski
Original assignee: Kone Corporation
Priority date: 2022-04-21
Filing date: 2022-04-21
Publication date: 2023-10-26
Also published as: EP4511304A1; CN118973933A

Abstract

A method for controlling a travel speed of an elevator car (120) is provided, the method, performed by a controller (220, 230), comprises: determining (310) an indicator value indicative of a vibration experienced by the elevator car (120) during a travel of the elevator car (120); controlling (320) the travel speed of the elevator car (120) by setting a control value to an elevator drive system (235) in accordance with the indicator value. Also an apparatus (220, 230) for controlling a travel speed of an elevator car (120), a computer program, and an elevator system are provided.

Description

CONTROL OF TRAVEL SPEED OF AN ELEVATOR CAR

TECHNICAL FIELD

The invention concerns in general the technical field of elevators. More particularly, the invention concerns controlling of elevator system.

BACKGROUND

High-rise buildings, such as in skyscrapers and similar, are impacted by environmental conditions in various way. One impact is caused by wind which makes the building to sway at its location due to that the wind blows past the high-rise building and creates a low-pressure area behind the building. The swaying may feel uncomfortable by inhabitants of the building but even if various design solutions have been developed the swaying cannot be fully eliminated in the high-rise buildings.

The swaying of the building impacts all structures inside the building. One such structure, or entity, being impacted is elevator system in the building. Naturally, the elevator system sways together with the building but especially the hoisting ropes are impacted, and they vibrate horizontally as a function of a position of an elevator car in the elevator shaft. As such the vibration is proportional to masses/inertia of the hoisting ropes, but also to other factors, such as to lengths of the hoisting ropes and weights of the elevator car and a counterweight, as is known from physics. For describing some further aspects it is referred to Figures 1A-1 C in which it is schematically illustrated the vibration of the hoisting rope 130 as the function of the position of the elevator car 120 in the shaft 110 running over the height of the building. It may e.g. be assumed that the elevator car 120 is traveling upwards in the building from the bottom floor to the top floor. When the elevator car 120 resides in the lower portion of the swaying high-rise building as shown in Figure 1A the vibration of the hoisting rope 130 is slow in terms of frequency and it may be hardly felt by the passengers in the elevator car 120. However, when the elevator car 120 travels upwards the length of the hoisting rope 130 between the elevator car 120 and the traction sheave shortens while the hoisting rope 130 maintains much of its kinetic energy, and as a result the frequency of the vibration of the hoisting rope 130 increases (Fig. 1 B). The vibration is at highest at least in terms of the frequency when the elevator car 120 is reaching the top floor (Fig. 1C), i.e. in the upper portion of the high-rise building, and the vibration of the hoisting rope 130 causes a shaking of the elevator car 120 and even noises, which all may scare the passengers in the elevator car 120. Furthermore, such vibration with high frequency and possibly with high amplitude may cause damages to elevator system, such as to the hoisting ropes and others.

According to prior art solutions the swaying of the building and its impact to the elevator system is taken into account by preventing a use of the elevator system when it is detected that the swaying of the building is significant e.g. in terms of travel comfort and/or the like. The swaying of the building is measured with an accelerometer attached to the building.

The drawback of the existing solution is that the reduction of the speed is performed in a static manner and by applying pre-fixed speed limits. Additionally, the measurement data descriptive of the swaying of the building does not necessarily represent the possible swaying of the hoisting ropes and, thus, the vibration experienced in the elevator car 120.

Hence, there is room for introducing novel approaches for mitigating at least in part an effect of the swaying of the building to the elevator system, or at least so that the user experience when traveling with the elevator remains satisfactory.

SUMMARY

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 a method, an apparatus, a computer program, and an elevator system for controlling a travel speed of an elevator car.

The objects of the invention are reached by a method, an apparatus, a computer program, and an elevator system as defined by the respective independent claims.

According to a first aspect, a method for controlling a travel speed of an elevator car is provided, the method, performed by a controller, comprises: determining an indicator value indicative of a vibration experienced by the elevator car during a travel of the elevator car, controlling the travel speed of the elevator car by setting a control value to an elevator drive system in accordance with the indicator value.

For example, the indicator value indicative of the vibration may be determined on a basis of data descriptive of at least one of the following: an acceleration experienced by the elevator car; a noise caused by a motion of the elevator car. At least part of the data descriptive of the acceleration experienced by the elevator car may be received at least from at least one accelerometer associated to the elevator car. Still further, a vertical component of the acceleration experienced by the elevator car may be determined by calculating a derivative of the travel speed of the elevator car. For example, data indicative of the travel speed of the elevator car may be obtained from at least one of the following: a speed sensor associated to the elevator car; an encoder of an electric motor; a speed estimate obtained from the elevator drive system; a torque estimate obtained from the elevator drive system.

Data descriptive of the noise caused by the motion of the electric car may also be received from a microphone associated to the elevator car. The controlling of the travel speed may be performed by setting, as the control value, one of the following: a target speed value, a target torque value.

The indicator value may be compared to a reference value for setting of the control value to an elevator drive system.

According to a second aspect, an apparatus for controlling a travel speed of an elevator car is provided, the apparatus is configured to: determine an indicator value indicative of a vibration experienced by the elevator car during a travel of the elevator car, control the travel speed of the elevator car by setting a control value to an elevator drive system in accordance with the indicator value.

The apparatus may be configured to determine the indicator value indicative of the vibration on a basis of data descriptive of at least one of the following: an acceleration experienced by the elevator car; a noise caused by a motion of the elevator car. The apparatus may be arranged to receive at least part of the data descriptive of the acceleration experienced by the elevator car at least from at least one accelerometer associated to the elevator car. Still further, the apparatus may be configured to determine a vertical component of the acceleration experienced by the elevator car by calculating a derivative of the travel speed of the elevator car. For example, the apparatus may be configured to obtain data indicative of the travel speed of the elevator car from at least one of the following: a speed sensor associated to the elevator car; an encoder of an electric motor; a speed estimate obtained from the elevator drive system; a torque estimate obtained from the elevator drive system.

The apparatus may also be configured to receive data descriptive of the noise caused by the motion of the electric car from a microphone associated to the elevator car. The apparatus may be configured to perform the controlling of the travel speed is by setting, as the control value, one of the following: a target speed value, a target torque value.

Still further, the apparatus may be at least one of: an elevator controller; a motion controller.

The apparatus may be configured to compare the indicator value to a reference value for setting of the control value to an elevator drive system.

According to a third aspect, a computer program is provided, the computer program comprising computer readable program code configured to cause performing of the method according to the first aspect as defined above when the computer readable program code is run on one or more computing apparatuses.

According to a fourth aspect, an elevator system is provided, the elevator system comprising an apparatus according to the second aspect as defined above.

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.

BRIEF DESCRIPTION OF FIGURES

The embodiments of the invention are illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings.

Figures 1 A-1 C illustrate schematically examples of an effect of a swaying of a building.

Figure 2 illustrates schematically an elevator system according to an example.

Figure 3 illustrates schematically a method according to an example.

Figure 4 illustrates schematically an apparatus according to an example.

DESCRIPTION OF THE EXEMPLIFYING EMBODIMENTS

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.

Figure 2 illustrates schematically an environment into which the present invention may be implemented to. The environment may be a high-rise building 200, such as a skyscraper or a tower, into which an elevator system may be implemented to. In Figure 2 it is illustrated only one elevator of the elevator system, but the number of elevators may vary from the one shown in Figure 2. An elevator car 120 of the elevator is arranged to travel in an elevator shaft 110. The elevator car 120 is equipped with at least one sensor 210 by means of which it is possible to generate measurement data for the purpose of the present invention as is described in the forthcoming description. For example, the at least one sensor 210 may be an accelerometer arranged to measure vibration experienced by the elevator car 120 during the travel. In accordance with some other example, the at least one sensor 210 may be a microphone arranged to detect noise along the travel path of the elevator car 120. In accordance with some examples, the elevator car 120 may be associated with a plurality of sensors 210 e.g. measuring different parameters descriptive either directly or indirectly of a vibration experienced by the elevator car 120 during the travel. In case of a plurality of sensors the implementation may be made as a sensor assembly e.g. by integrating the sensors and any control logic to the same integrated circuit (IC) board.

An overall operation of the elevator system may be controlled by an elevator controller 220 which is communicatively connected, either directly or indirectly, in a known manner to various entities of the elevator system. The elevator controller 220 may also receive the measurement data from the at least one sensor 210 over a wired or a wireless communication. As said, the elevator controller 220 is communicatively connected to various entities and one such entity may be a motion controller 230 being a part of an elevator drive 235 which is configured to control a machinery 240 of the elevator e.g. by supplying and controlling electric power input to the machinery 240. In other words, the motion controller 230 generates such control signals that the elevator drive 235 is capable of controlling the machinery 240 so that a motion of the elevator car 120 may be controlled e.g. in terms of a travel speed. The elevator machinery 240 may be understood to comprise at least an electric motor, a traction sheave over which a hoisting rope 130 travels, and machinery brake, for example. The machinery may also comprise one or more sensors 250 by means of which it is possible to generate measurement data indicative of a state of the machinery, such as if a shaft is rotating or not and/or at which speed it is rotating and/or a torque of the electric motor. For example, the data obtainable from a motor encoder as the sensor 250 may be used to determine such pieces of information. Moreover, based on the measurement data it is possible to derive various values indicative of a motion of the elevator car 120, such as a travel speed of the elevator car 120, for example. The sensor data from the machinery sensors 250 may e.g. be collected by the motion controller 230, which may also be arranged to receive the measurement data from the sensor 210 associated to the elevator car 120 either directly or indirectly, such as through the elevator controller 220. The data received from the sensors may be raw data or preprocessed in any applicable manner in order to be applied in the manner as described herein.

Next, further aspects in relation to the present invention are described by referring to Figure 3 schematically illustrating an example of a method. The method may be performed by an apparatus provided with necessary computing resources. For example, the apparatus configured to perform the method may be an elevator controller 220, a motion controller 230, or it may also be performed in a device arranged in the elevator car and e.g. comprising the sensor(s) 210. Still further, the apparatus may be an external computing device. In accordance with some examples, the computing may be shared between distinct control devices, such as the ones mentioned above. Naturally, in order to perform the method necessary pieces of data, such as the measurement data form the respective sensors 210, 250 in accordance with the implementation shall be arranged accessible to the respective apparatus.

At least one aim of the method is to enable controlling a travel speed of an elevator car 120 of the elevator system so that it takes into account vibration experienced by the elevator car 120 during the travel of the elevator car 120, especially to upward direction, due to a swaying of the building 200 which causes swaying effect to the hoisting rope 130. In step 310, the apparatus i.e. the controller is arranged to determine 310 an indicator value indicative of a vibration experienced by the elevator car 120 during a travel of the elevator car 120. In order to determine 310 the indicator value the controller, such as the elevator controller 220 may be provided with an access to data from which the indicator value may be determined 310. The access to the data may correspond to that the controller receives measurement data from at least one sensor 210, 250 as a raw data or preprocessed data and is configured to perform necessary processing to determine 310 the indicator value. In accordance with some example embodiments the indicator value indicative of the vibration experienced by the elevator car 120 may be determined on a basis of data descriptive of at least one of the following: an acceleration experienced by the elevator car 120; a noise caused by a motion of the elevator car 120. For example, at least part of the data descriptive of the acceleration experienced by the elevator car 120 may be received at least from at least one accelerometer associated to the elevator car 120 as the sensor 210. The accelerometer may be such that it is capable of generating data indicative of the accelerometer in 3-dimensional space, i.e. the data is received as component values in x, y, and z directions. Thus, it is possible to determine the vibration experienced by the elevator car 120 horizontally and vertically. In some other example embodiment the vibration experienced horizontally may be determined from the respective accelerometer associated to the elevator car 120. In some other embodiments, the horizontal component of the vibration may be obtained from a torque estimate generated by an elevator drive system 235, cf. a frequency converter, controlled at least in part by the motion controller 230. Moreover, the vertical component of the acceleration, and, hence, the vibration, may be determined by calculating a derivative of the travel speed of the elevator car 120. The data indicative of the travel speed of the elevator car 120 may be obtained from e.g. a speed sensor associated to the elevator car 120 or from data obtainable from an encoder 250 of an electric motor in the machinery 240. Further possibilities to obtain data indicative of the travel speed of the elevator car 120 may be to use a speed estimate or a torque estimate obtainable from the elevator drive system 235, cf. the frequency converter, controlled at least in part by the motion controller 230, or measuring or estimating a rotation speed of the hoisting motor, i.e. the electric motor, of the machinery 240 for that purpose. As already mentioned, the raw data received from the respective sensors, and especially the raw data indicative of the vibration, may require some preprocessing, such as applying some statistical method like using the root-mean square operation to the raw data to make it usable for the purpose of the present invention. Also other mathematical operations may be applied to such as taking a first derivative with respect to a time from raw data expressing a speed of the elevator car as already mentioned above. In case the raw data expresses a position of the elevator car a second derivative may be applied to the data in order to obtain values indicative of the vibration. For sake of completeness it is worthwhile to mention, as is clear from above, that the data used for evaluating the vibration may be received from sensors arranged in the elevator car 120 or from sensors 250 or other sources arranged or available in the machinery 240 and/or motion controller 230.

In accordance with another example embodiment the data for determining 320 the indicator value may be based on data descriptive of the noise caused by the motion of the electric car 120. The fundamental idea at least in part here is that the more vibration the elevator car 120 is experiencing due to the swaying of the building 200 the more motion, e.g. horizontally, occur at a certain frequency, and the more noise is generated by the motion of the elevator car 120 e.g. due to that the elevator car 120 is deviated from its optimal path defined by the guide rails and similar. To obtain data descriptive of the noise caused by the motion of the electric car 120 at least one microphone may be associated to the elevator car 120 to record a soundscape over the travel of the elevator car 120.

In accordance with the method according to the example the controller is configured to, in response to the determining 310 of the indicator value, control the travel speed of the elevator car 120 by setting a control value to an elevator drive system 235 in accordance with the indicator value. In other words, the controller is configured to dynamically control the travel speed of the elevator car 120 dependently on the determined indicator value. The control of the travel speed may be arranged as a feedback loop in which, in response to a detection that the vibration is unacceptable, the travel speed is incrementally decreased until an acceptable vibration is detected. In at least some embodiments, the acceptable vibration may be defined as a reference value which may be constant, or it may be adjusted with respect to a travel speed at a desired accuracy. The reference value may be used in a comparison with the determined indicator value to determine if the vibration is acceptable or not in order to set the control value to the elevator drive system 235. For example, the control value may be descriptive on a request of the incremental decrease of the travel speed. In order to control the travel speed the controller may be configured to generate the control value in accordance with an entity with whom it is communicated about the control. In accordance with some example embodiment the controlling of the travel speed may be performed by setting, as the control value to the elevator drive system 235 which, in turn, generates a control signal to the machinery, and especially to the electric motor therein in a known manner. Another applicable parameter may be a target torque value requested to be generated by the electric motor of the machinery 240. According to some embodiments the controller may be configured to determine a value defining a required decrease in the travel speed which is then delivered to respective entity to achieve the limitation in the travel speed. In accordance with an embodiment it may be arranged that in a special case when it is detected that the vibration is so huge that it cannot be rapidly controlled with the incremental controlling, or upon a detection that the vibration suddenly increases remarkable, it may be arranged that the controller instructs the elevator car 120 to stop immediately, such as by applying emergency stop routines, so as to avoid any damages in the elevator system.

For sake of completeness in case the controller configured to perform the controlling of the travels speed by implementing the method as described is the motion controller 230 it may directly define the control values for the machinery 240. On the other hand, if the controller performing the method is either the elevator controller 220 or the entity traveling along with the elevator car 120 it may generate data providing the motion controller 230 information how to generate the control signal for the machinery 240 to perform the controlling.

Figure 4 illustrates schematically an example of an apparatus suitable for performing the method as described in the role of the controller. In other words, the apparatus of Figure 4 may e.g. be configured to perform a function to control of a travel speed of an elevator car 120 of an elevator system. For sake of clarity, it is worthwhile to mention that the block diagram of Figure 4 depicts some components of an entity that may be employed to implement a functionality of the apparatus. The apparatus comprises a processor 410 and a memory 420. The memory 420 may store data, such as pieces of data as described, but also computer program code 425 causing the control of the travel speed of the elevator car 120 of the elevator system in the described manner. The apparatus may further comprise a communication interface 430, such as a wireless communication interface or a communication interface for wired communication, or both to communicate with other entities as described. The communication interface 430 may thus comprise one or more modems, antennas, and any other hardware and software for enabling an execution of the communication e.g. under control of the processor 410. Furthermore, I/O (input/output) components may be arranged, together with the processor 410 and a portion of the computer program code 425, to provide a user interface for receiving input from a user, such as from a technician, and/or providing output to the user of the apparatus when necessary. In particular, the user I/O components may include user input means, such as one or more keys or buttons, a keyboard, a touchscreen, or a touchpad, etc. The user I/O components may include output means, such as a loudspeaker, a display, or a touchscreen. The components of the apparatus may be communicatively connected to each other via data bus that enables transfer of data and control information between the components.

The memory 420 and a portion of the computer program code 425 stored therein may further be arranged, with the processor 410, to cause the apparatus to perform at least a portion of a method as is described herein. The processor 410 may be configured to read from and write to the memory 420. Although the processor 410 is depicted as a respective single component, it may be implemented as respective one or more separate processing components. Similarly, although the memory 420 is depicted as a respective single component, it may be implemented as respective one or more separate components, some, or all of which may be integrated/removable and/or may provide permanent / semi-permanent / dynamic / cached storage. The computer program code 425 may comprise computer-executable instructions that implement functions that correspond to steps implemented in the controlling of the travel speed of the elevator car 120 of the elevator system when loaded into the processor 410 of the respective controller, such as into the processor 410 the elevator controller 220 or into the processor 410 of the motion controller 230. As an example, the computer program code 425 may include a computer program consisting of one or more sequences of one or more instructions. The processor 410 is able to load and execute the computer program by reading the one or more sequences of one or more instructions included therein from the memory 420. The one or more sequences of one or more instructions may be configured to, when executed by the processor 410, cause the apparatus to perform a method as described. Hence, the apparatus may comprise at least one processor 410 and at least one memory 420 including the computer program code 425 for one or more programs, the at least one memory 420 and the computer program code 425 configured to, with the at least one processor 410, cause the apparatus to perform the method.

The computer program code 425 may be provided e.g. a computer program product comprising at least one computer-readable non-transitory medium having the computer program code 425 stored thereon, which computer program code 425, when executed by the processor 410 causes the apparatus to perform the method. The computer-readable non-transitory medium may comprise a memory device or a record medium, such as a CD-ROM, a DVD, a Blu-ray disc, or another article of manufacture that tangibly embodies the computer program. As another example, the computer program may be provided as a signal configured to reliably transfer the computer program.

Still further, the computer program code 425 may comprise a proprietary application, such as computer program code for causing an execution of the method in the manner as described in the description herein.

Any of the programmed functions mentioned may also be performed in firmware or hardware adapted to or programmed to perform the necessary tasks. For sake of completeness it is worthwhile to mention that the entity performing the method as the role of the control system may also be implemented with a plurality of apparatuses, such as the one schematically illustrated in Figure 4, as a distributed computing environment corresponding to a control system. For example, one of the apparatuses may be communicatively connected with the other apparatuses, and e.g. share the data of the method, to cause another apparatus to perform at least one other portion of the method. As a result, the method performed in the distributed computing environment generates the result as described. For example, some steps of the method may be shared between the elevator controller 220, the motion controller 230, and even with the sensor assembly 210 associated to the elevator car 120.

The effect of swaying of the building 200 is mainly experienced by the elevator system, and especially by the elevator car 120, when a direction of the travel is upwards, since the length of the hoisting rope 130 shortens during the travel and a frequency of the swaying, and thus the vibration of the elevator car 120, increases correspondingly. However, the present invention is not limited to an application in the upward direction only, but the control of the travel speed of the elevator car 120 may be similarly performed when the direction of the travel is downwards. For example, the swaying may suddenly increase during the travel and adjustment in the travel speed is required also then. Furthermore, the invention is not only limited to reducing the travel speed, but it may also be increased upon a detection that the vibration experienced by the elevator car 120 is decreased. Thus, the solution according to the invention controls the travel speed with the feedback loop to any direction.

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.

Claims

WHAT IS CLAIMED IS:

1. A method for controlling a travel speed of an elevator car (120), the method, performed by a controller (220, 230), comprises: determining (310) an indicator value indicative of a vibration experienced by the elevator car (120) during a travel of the elevator car (120), controlling (320) the travel speed of the elevator car (120) by setting a control value to an elevator drive system (235) in accordance with the indicator value.

2. The method according to claim 1 , wherein the indicator value indicative of the vibration is determined on a basis of data descriptive of at least one of the following: an acceleration experienced by the elevator car (120); a noise caused by a motion of the elevator car (120).

3. The method according to claim 2, wherein at least part of the data descriptive of the acceleration experienced by the elevator car (120) is received at least from at least one accelerometer associated to the elevator car (120).

4. The method according to claim 3, wherein a vertical component of the acceleration experienced by the elevator car (120) is determined by calculating a derivative of the travel speed of the elevator car (120).

5. The method according to claim 4, wherein data indicative of the travel speed of the elevator car (120) is obtained from at least one of the following: a speed sensor (210) associated to the elevator car (120); an encoder of an electric motor; a speed estimate obtained from the elevator drive system (235); a torque estimate obtained from the elevator drive system (235).

6. The method according to claim 2, wherein data descriptive of the noise caused by the motion of the electric car (120) is received from a microphone associated to the elevator car (120).

7. The method according to any of the preceding claims, wherein the controlling of the travel speed is performed by setting, as the control value, one of the following: a target speed value, a target torque value.

8. The method according to any of the preceding claims, wherein the indicator value is compared to a reference value for setting of the control value to an elevator drive system (235).

9. An apparatus (220, 230) for controlling a travel speed of an elevator car (120), the apparatus (220, 230) is configured to: determine (310) an indicator value indicative of a vibration experienced by the elevator car (120) during a travel of the elevator car (120), control (320) the travel speed of the elevator car (120) by setting a control value to an elevator drive system (235) in accordance with the indicator value.

10. The apparatus (220, 230) according to claim 9, wherein the apparatus (220, 230) is configured to determine the indicator value indicative of the vibration on a basis of data descriptive of at least one of the following: an acceleration experienced by the elevator car (120) ; a noise caused by a motion of the elevator car (120).

11 . The apparatus (220, 230) according to claim 10, wherein the apparatus (220, 230) is arranged to receive at least part of the data descriptive of the acceleration experienced by the elevator car (120) at least from at least one accelerometer associated to the elevator car (120).

12. The apparatus (220, 230) according to claim 11 , wherein the apparatus (220, 230) is configured to determine a vertical component of the acceleration experienced by the elevator car (120) by calculating a derivative of the travel speed of the elevator car (120).

13. The apparatus (220, 230) according to claim 12, wherein the apparatus (220, 230) is configured to obtain data indicative of the travel speed of the elevator car (120) from at least one of the following: a speed sensor (210) associated to the elevator car (120); an encoder of an electric motor; a speed estimate obtained from the elevator drive system (235); a torque estimate obtained from the elevator drive system (235).

14. The apparatus (220, 230) according to claim 10, wherein the apparatus (220, 230) is configured to receive data descriptive of the noise caused by the motion of the electric car (120) from a microphone associated to the elevator car (120).

15. The apparatus (220, 230) according to any of the preceding claims 9 to

14, wherein the apparatus (220, 230) is configured to perform the controlling of the travel speed by setting, as the control value, one of the following: a target speed value, a target torque value.

16. The apparatus (220, 230) according to any of the preceding claims 9 to

15, wherein the apparatus (220, 230) is at least one of: an elevator controller (220); a motion controller (230).

17. The apparatus (220, 230) according to any of the preceding claims 9 to

16, wherein the apparatus (220, 230) is configured to compare the indicator value to a reference value for setting of the control value to an elevator drive system (235).

18. A computer program comprising computer readable program code configured to cause performing of the method according to any of claims 1 to 8 when the computer readable program code is run on one or more computing apparatuses.

19. An elevator system comprising an apparatus (220, 230) according to any of claims 9 to 17.