TECHNICAL FIELD

The invention concerns in general the technical field of elevators. More particularly, the invention concerns a solution for controlling a safety of an elevator.

BACKGROUND

An operation of an elevator system is based on a vertical motion of elevator cars in an elevator shaft between landings. The force to the vertical motion of the elevator car is generated with an elevator drive system comprising a plurality of entities, such as a hoisting machine consisting of an electric motor and a traction sheave mounted to an axis of the electric motor, as well as a power converter for supplying power to the electric motor. The elevator car may be coupled to the rotation of the traction sheave via a hoisting roping so that elevator car moves when the electric motor drives the traction sheave.

As is known the elevator system is used for transporting passengers and cargo between the landings the elevator car in question serves. The elevator system in question is allowed carry a predefined amount of load defined by an implementation of the elevator system, such as the elevator drive system among other entities. Besides, the elevator system shall comply with safety standards defined for elevator systems. Thus, a loading of the elevator car is monitored with a weighing device in order to receive information on the amount of load for deciding in an operation of the elevator shall be allowed or not. The weighing devices applied in the context of the elevators may e.g. be based on a pressure sensor arranged in the elevator car floor, a strain gauge arranged to measure a depression of the elevator car floor or tension of the hoisting roping, or a current sensor arranged to measure motor current required to keep elevator car still while elevator brakes are open. In order to improve safety there are introduced some solutions to confirm that the applied weighing device operates properly and, hence, reduce a risk that the elevator car is allowed to travel due to a malfunction of the weighing device even if the load in the elevator car exceeds an applied limit. The known approaches are based on arranging mutually independent weighing devices to provide measurement results for comparing if a first weighing device is operating properly or not on the basis of the measurement result obtained from a second weighing device. Such a solution is e.g. described in a document EP 2998259 A1 .

Even if the known approaches are operative as such there may be introduced alternative approaches to confirm an operation of a weighing device of the load of the elevator car so as to improve the safety of the elevator system.

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 an elevator system, a method, a computer program, and an apparatus for controlling of an operation of an elevator system.

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

According to a first aspect, an elevator system is provided, the elevator system comprising: an elevator car, a weighing device for measuring a weight of a load in the elevator car, the elevator system further comprises: an apparatus configured to generate data indicative of a passenger flow with respect to the elevator car, and an apparatus configured to: receive data from the weighing device, receive data from the apparatus configured to generate data indicative of a passenger flow with respect to the elevator car, detect if information derivable from the data received from the apparatus configured to generate the data indicative of the passenger flow with respect to the elevator car corresponds to information derivable from the data received from the weighing device, and set, in accordance with a correspondence between the information derivable from the data received from the apparatus configured to generate the data indicative of the passenger flow with respect to the elevator car and the information derivable from the data received from the weighing device, an indication to express one of the following: (i) the weighing device operates properly, (ii) the weighing device malfunctions.

For example, the apparatus configured to generate the data indicative of the passenger flow with respect to the elevator car may be an elevator controller.

The apparatus configured to generate data indicative of a passenger flow with respect to the elevator car may be at least one of: an image capturing device; a light curtain; a receiver of an electromagnetic radiation. For example, the image capturing device may be arranged in one of: at one or more landings the elevator car serves; in the elevator car. On the other hand, the light curtain may be arranged at a door zone of the elevator car. Still further, the receiver may be arranged in the elevator car.

The apparatus may be arranged to receive data from the apparatus configured to generate data indicative of a passenger flow with respect to the elevator car over a time window an elevator door is instructed to be open.

Still further, the apparatus may be arranged to detect if information derivable from the data received from the apparatus configured to generate the data indicative of the passenger flow with respect to the elevator car corresponds to information derivable from the data received from the weighing device by one of the following manner: (i) both pieces of information indicate a change in the weight of the load in the elevator car; (ii) a direction of a change in a weight of the load in the elevator car based on the on the information derivable from the data received from the apparatus configured to generate the data indicative of the passenger flow with respect to the elevator car corresponds to a direction of change in a weight of the load in the elevator car based on the information derivable from the data received from the weighing device; (iii) an amount of a change in a weight of the load in the elevator car based on the information derivable from the data received from the apparatus configured to generate the data indicative of the passenger flow with respect to the elevator car corresponds to an amount of a change in a weight of the load in the elevator car based on the information derivable from the data received from the weighing device.

The apparatus may also be configured to, in response to setting the indication to express that the weighing device malfunctions, to perform at least one of: generate a control signal to limit an operation of the elevator system; generate a signal to service centre to express the malfunctioning of the weighing device; generate a signal to increase a counter configured to count a number of indications expressing that the weighing device malfunctions.

According to a second aspect, a method for controlling an operation of an elevator system is provided, the method comprises: receiving, by an apparatus, data from a weighing device configured to provide information on a weight of a load in an elevator car, receiving, by the apparatus, data from an apparatus configured to generate data indicative of a passenger flow with respect to the elevator car, detecting, by the apparatus, if information derivable from the data received from the apparatus configured to generate the data indicative of the passenger flow with respect to the elevator car corresponds to information derivable from the data received from the weighing device, and setting, by the apparatus, in accordance with a correspondence between the information derivable from the data received from the apparatus configured to generate the data indicative of the passenger flow with respect to the elevator car and the information derivable from the data received from the weighing device, an indication to express one of the following: (i) the weighing device operates properly, (ii) the weighing device malfunctions.

For example, a receipt of data from the apparatus configured to generate data indicative of a passenger flow with respect to the elevator car may be performed over a time window an elevator door is instructed to be open.

Still further, a detection if information derivable from the data received from the apparatus configured to generate the data indicative of the passenger flow with respect to the elevator car corresponds to information derivable from the data received from the weighing device may be performed based on one of: (i) both pieces of information indicate a change in the weight of the load in the elevator car; (ii) a direction of a change in a weight of the load in the elevator car based on the on the information derivable from the data received from the apparatus configured to generate the data indicative of the passenger flow with respect to the elevator car corresponds to a direction of change in a weight of the load in the elevator car based on the information derivable from the data received from the weighing device; (iii) an amount of a change in a weight of the load in the elevator car based on the information derivable from the data received from the apparatus configured to generate the data indicative of the passenger flow with respect to the elevator car corresponds to an amount of a change in a weight of the load in the elevator car based on the information derivable from the data received from the weighing device.

The method may further comprise, in response to setting the indication to express that the weighing device malfunctions, at least one of: a generation of a control signal to limit an operation of the elevator system; a generation of a signal to service centre to express the malfunctioning of the weighing device; a generation of a signal to increase a counter configured to count a number of indications expressing that the weighing device malfunctions.

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

According to a fourth aspect, an apparatus for controlling an operation of an elevator system is provided, the apparatus is configured to perform the method according to the second aspect as defined above.

For example, the apparatus may be an elevator controller.

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.

Figure 1 illustrates schematically an elevator system according to an example.

Figure 2 illustrates schematically a method according to an example.

Figure 3 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.

The present invention provides a solution for improving a safety of an elevator system 1000 as shown as an example in Figure 1. The elevator system of Figure 1 comprises an elevator car 1 10 and a counterweight 120 arranged to move vertically in an elevator shaft 130. The elevator car 100 and the counterweight 120 are suspended with a hoisting roping 140 which is arranged to run over a traction sheave of a hoisting machine 150 which hoisting machine 150 consists of an electric motor in addition to the traction sheave. The hoisting machine 150 may be considered to belong to an elevator drive system which also comprises a frequency converter 160 configured to provide an input current to the electric motor in a known manner. The operation of the frequency controller 160, and thus the hoisting machine 150, is controlled by an elevator controller 170 which may have an overall responsibility of the operation of the elevator system 1000. As is commonly known the elevator system 1000 may comprise a number of other entities, such as call-giving devices and signalization device which provide interfaces to receive and provide information from and to passengers and other tenants in the building the elevator system 1000 resides.

From a perspective of the present invention the elevator system 1000 comprises at least one weighing device 180 by means of which a loading of the elevator car 1 10 may be determined. The weighing device 180 may comprise a sensor, such as a pressure sensor arranged in the elevator car floor, a strain gauge arranged to measure a depression of the elevator car floor or tension of the hoisting roping, or a current sensor arranged to measure motor current required to keep elevator car still while elevator brakes are open, or any similar sensor by means of which a weight of the load, or its proportion compared to a maximum allowable load, may be determined. Hence, the weighing device 180 shall be understood to cover one or more devices being involved in determining the described aspect. For example, the weighing device 180 may comprise the sensor and a computing device configured to process the data obtainable from the respective sensor, or sensors, In accordance with an embodiment the computing device may be the elevator controller 170, or it may be a dedicated computing device to generate the information and to provide the generated information to the elevator controller 170, or to any other apparatus, cf. an applicable computing device, configured to perform a method according to the present invention. In order to receive the data from the weighing device 180, or at least from the sensor, a communication path is arranged either by applying wireless or wired communication technologies between the communicating entities. For example, the entities may be communicatively connected to a data bus of the elevator system 1000.

In accordance with the present invention the operation of the weighing device is arranged to be confirmed with an apparatus, or an arrangement, by means of which it is possible to monitor passenger flow to and from an elevator car 1 10 of the elevator system 1000 in question. The passenger flow monitoring is arranged by using an apparatus configured to obtain data based on a monitoring of radiation, such as light, in one way or another. In accordance with an embodiment the apparatus applied to monitoring of the passenger flow may be an image capturing device 190 by means of which it is possible to monitor a door zone of the elevator car 1 10 and, hence, to capture images in the area. The door zone may be understood in the context of the present invention, and especially in the embodiments in which the image capturing device 190 is applied to, to refer to a predefined area with respect to the elevator door through which a passenger moves when entering or exiting the elevator car 1 10 with a probability defined to be acceptable. For example, the door zone may refer to an area defined by the door frame, e.g. centered to the centerline of the elevator door. Alternatively or in addition, the door zone may extend a predefined section towards the elevator car 1 10 and/or towards the hall area. Advantageously, the door zone is defined so that the passengers do not reside in the zone e.g. when being inside the elevator car 1 10 or at the landing e.g. when waiting for an elevator. Naturally, the door zone is adjusted with respect to the image capturing device 190, and/or vice versa, so that the door zone is withing a field of view of the image capturing device 190. The image capturing device 190 may be positioned in a hall area of the landing so that it may be focused to the door zone. Alternatively, the image capturing device 190 may be mounted inside the elevator car 1 10 for monitoring the passenger flow of the elevator car 110, i.e. changes in a number of passengers inside the elevator car 190. According to another example embodiment the apparatus applied to a monitoring of the passenger flow may be a light curtain 195 arranged to monitor passenger traffic at the door zone of the elevator car 1 10 e.g. by mounting the light curtain 195 to a door frame. The light curtain 195 shall be understood as a detection device whose operation is based on a detection if one or more light rays are blocked to travel from a transmitter to a received e.g. due to that a passenger blocks the travel of the light. Still further approaches within the inventive idea of the present invention may be based on an application of radiation in other forms than light. For example, an application of a short-range communication technology for the purpose of the present invention may be arranged e.g. in a manner that a receiver device 197 is arranged e.g. inside the elevator car 110 and in response to an interaction with a transmitter device e.g. carried by a passenger an evaluation of a passenger flow may be performed. For example, if the applied communication technology is Bluetooth the transmitter carried by the passenger may be arranged to connect with the Bluetooth receiver when the transmitter resides inside the elevator car 1 10. Hence, a detection if inflowing passenger traffic may be performed and when the connection is disconnected due to that the passenger exits the elevator car 1 10, an indication of an outflow of one or more passengers may be detected. Other communication technologies, such as infrared, or NFC technologies may also be applied to in the context of the present invention i.e. the apparatus referred as the receiver device 197 may be configured to communicate with electromagnetic radiation with the transmitter.

The data captured by the applied apparatus 190, 195 used for monitoring the passenger flow to and from the elevator car 1 10 at the respective landing is delivered to an apparatus configured to perform the method according to the present invention. The delivery of the data may be arranged with a communication connection implemented between the apparatus, e.g. 170, configured to perform the method and the one or more apparatuses 190, 195 configured to obtain the data representing the passenger flow of the elevator car 1 10. The communication connection may be established either by applying wireless or wired communication technologies.

For sake of clarity it is worthwhile to mention that the monitoring of the passenger flow shall be understood in a broad manner i.e. covering both that the passengers are human beings but also that the passengers are other type of passengers, such as cargo, robots, animals, or any combination of these.

Furthermore, the detection of the passenger flow based on the data received from the detection apparatus 190, 195, 197 may be performed in a variety of ways. In accordance with an example embodiment it may be necessary only to detect that an amount of load in the elevator car 1 10 changes which corresponds either that passengers either enter the elevator car 1 10 or exit therefrom. In some other example embodiments it may be necessary to determine a direction of the traffic based on the data received from the detection apparatuses 190, 195, 197. In case the data is a number of images obtained with the image capturing device 190 an applicable pattern recognition procedure may be performed to the image data so as to detect if passengers are present in the images. In case it is necessary to determine the direction of the passenger traffic, the pattern recognition procedure, such as an algorithm, may be configured to be applied to a consecutive images so as to detect to which direction the object, i.e. a passenger, moves to with respect to the elevator car 1 10, i.e. at the door zone. The images selected to the pattern recognition for the purpose of the present invention are advantageously those which are captured at the door zone while the elevator doors are open. For example, the elevator controller 170 may be configured to control the image capturing and trigger it to occur based on the door control signals, e.g. between the opening and closing signals, or it may be configured to insert a tag to images captured during the door is open, for example. In case the applied detection apparatus 190, 195, 197 is the light curtain device 195 the detection of the change of the load in the elevator car 1 10 may be directly detected based on a detection that a generated light curtain is blocked by an object. In case, it is necessary to detect the direction of the passenger traffic a plurality of light curtain devices 195 may be arranged at the door zone so that the passengers blocks first one of these and after that the other one by moving at the door zone, and based on these detection, and their order, it is possible to determine the direction of the movement. Alternatively or in addition, some further data may be combined with the detection with only one light curtain device 195 if the direction is important to determine. Moreover, in case the detection apparatus 190, 195, 197 is a wireless communication device, such as a receiver 197 of a certain communication technology the detection of the change in load may be based on a detection of a number of connected devices with the receiver, e.g. in the manner as described in the foregoing description. In such an approach it may be assumed that the connected devices are carried by human passengers having a certain weight, i.e. default weight, for example. Alternatively or in addition, the transmitter may be configured to deliver data indicative of a weight of the carrier of the transmitter upon the communicative interaction with the receiver. Such piece of data may be stored in a memory of the transmitter carried by the passenger and inquired therefrom. This kind of approach is especially advantageous in case the passenger is cargo since the system as described may obtain information on the weight of cargo through the communication between the transmitter and the receiver. The distinction in weights of the passengers may also be arranged by providing different kinds of transmitters, e.g. sending different identifier, to different types of passengers, such as human passengers, cargo, animals, robots, and so on, which are linked to different kinds of default weights. Hence, by receiving the identifiers of the transmitters communicatively connected to the receiver, the passenger flow, such as any change in the weight of the load of the elevator car 1 10, may be determined in at least some accuracy. As said, the transmitter and the receiver may be arranged to implement e.g. a Bluetooth technology, Near Field Communication, NFC, technology, infrared technology, ZigBee technology, or any similar. The transmitter carried by the passenger may e.g. be a mobile terminal, a radio transmitter, a tag (cf. NFC tag), or any similar. Depending on the selected technology, and its capabilities, the evaluation of the passenger flow, such as a change of weight of the load in the elevator car 110, may be based on a number of connected, or detected, devices in the coverage area of the receiver 197, data exchanged over the communication, or even on evaluating a strength of an electromagnetic connection between the communicating entities, or on anything similar, which allows to make conclusions on the passenger flow of the elevator car 1 10 to be used in the manner as described herein.

For sake of completeness it is worthwhile to mention applying the image capturing device 195 for the evaluation of the passenger flow, and especially to evaluate an amount of change in the load, has at least some advantages over the other solutions as described because a machine-learning model may be trained, based on the image data, to evaluate a change in the load of the elevator car 1 10 based on an analysis of the image data. In other words, the machine-learning model, by executing it in a computing unit, may be configured to identify an object moving in the elevator car 1 10 and/or out from the elevator car 1 10 and based on the identification it is possible obtain data, e.g. from a database storing respective data, on the weight of the identified object. This kind of approach may take an accuracy of the solution to a sophisticated level. In some case the accuracy may be adjusted in accordance with the accuracy of the weighing device so that the values obtained from the two systems are comparable. For example, on objects detected to have a weight exceeding a predefined limit may be taken into account for the purpose of the present invention.

Next further aspects with respect to the present invention is described by referring to Figure 2 schematically illustrating an example of a method according to the present invention. As already mentioned, an aim of the invention is to improve a safety of the elevator system 1000 by controlling an operation of the elevator system so that an operational condition of at least one entity of the elevator system is evaluated, i.e. an operational condition of a weighing device 180 is evaluated by determining if the weighing device 180 operates properly or if it is malfunctioning. The method may be performed with an applicable apparatus, such as a computing device, which may be considered to be an elevator controller 170, for example, and it is now assumed in the forthcoming description that the apparatus is the elevator controller 170. In accordance with the example embodiment the elevator controller 170 may be configured to receive 210 data from the weighing device 180 and to receive 220 data from at least one apparatus 190, 195, 197 configured to obtain the data representing a passenger flow of the elevator car 1 10. Herein the term apparatus may refer to a respective sensor and/or to a device configured to generate data in question i.e. the device may comprise the sensor and other entities, such as memory and processing unit. The data may be received 210, 220 from the respective apparatuses 180, 190, 195, 197 in a continuous manner or over a predefined time window. In some sophisticated embodiments an amount of the received data may be optimized by arranging that the data from the weighing device 180 is received continuously, or at least over a time window the elevator car 1 10 stays at a landing. Furthermore, the data received from the passenger flow monitoring apparatus 190, 195 may be received, or obtained, only at instants of time it is desired to perform a safety check for the weighing device 180. In a non-limiting example it may be arranged that the data received from the respective apparatus so that the receipt of data is triggered with a control signal causing an opening of the elevator door. Correspondingly, the receipt of data may be ended when a control signal to close the elevator doors is given. Also, it may be arranged that the reference value at least for the weighing device may be stored during the travel of the elevator car 1 10, e.g. just before the landing, so that the change may be evaluated compared to that. Similarly, any reference value may be obtained for the apparatus 190, 195, 197 especially if it obtainable from a device arranged to operate inside the elevator car 1 10. Naturally, the instant of time for capturing the reference parameters may occur at any time prior to that passengers enters or exits the elevator car 1 10, or even so that the time window of the monitoring is set so short that only one passenger may exit or enter the elevator car 1 10 as long as both the systems, i.e. the weighing device 180 and the apparatus 190, 195, 197 are generating data from the same phenomenon.

Upon a receipt of the described pieces of data the elevator controller 170 is configured to perform a detection 230 based on the received pieces of information. The detection 230 may be performed in a manner providing an accuracy by means of which it is possible to judge if the weighing device 180 operates properly or not. Different example embodiments of the implementation of the detection step 230 are discussed in the following paragraphs.

According to a first example embodiment the detection step 230 may be arranged so that it is monitored that a value representing a weight received from the weighing device 180 changes upon a detection, by analyzing data received from the passenger flow monitoring apparatus 190, 195, that there has occurred passenger flow to and/or from the elevator car 1 10. In other words, if the data obtainable from the one or more images captured with the image capturing device 190 or from the data generated by the light curtain device 195 indicates that there has occurred passenger traffic to the elevator car 1 10 or from the elevator car 1 10, or even both, it may be expected that such a passenger traffic causes a change in the weight value obtainable from the measurement data received from the weighing device 180. If such a change may be detected based on the received data, e.g. based on at least to consecutive measurement values, from the weighing device, it may be concluded that the weighing device 180 operates properly and the operation of the elevator system 1000 may be based at least in part to the data obtainable from the weighing device 180. Hence, an indication on the proper operation may be generated 240. On the other hand, if the weight based on the measurement data received from the weighing device 180 does not change even if such a detection is made from the data received from the passenger flow monitoring apparatus 190, 195, it may be concluded that the weighing device 180 is malfunctioning and a respective indication may be generated 250.

According to a second embodiment the detection step 230 may be implemented to provide more accurate information than is available with the implementation according to the first example embodiment as described above. In the second example embodiment a direction of the passenger flow may be determined from the data received from the passenger flow monitoring device 190, 195 and based on that to generate an indication if the weight is increasing or decreasing in the elevator car 1 10 based on the data also indicative of the direction of the passenger flow. Now, the outcome derived based on the data received from the passenger flow monitoring device 190, 195 is compared to the data derivable from the measurement data from the weighing device 180 for performing the detection 230. In other words, in case the operation of the weighing device 180 may be considered appropriate the change in weight based on the measurement data from the weighing device 180 shall correspond to the outcome derived from the data indicative of the direction of the passenger flow. In other words, if it is determined that the passenger flow is outwards from the elevator car 1 10, the weight in the elevator car 1 10 shall decrease, and if it is determined that the passenger flow is to the elevator car 1 10, the weight in the elevator car 1 10 shall increase. If this kind of correspondence, or dependency, is not detectable, it may be concluded that the weighing device 180 is malfunctioning (cf. step 250 in Figure 2). On the other hand, if the correlation in the measurement data obtained from the plurality of sources may be found, it may be concluded that the weighing device 180 operates properly (cf. step 240 in Figure 2).

In even more sophisticated embodiment the implementation of the second embodiment may be developed so that an estimation of the change in weight is generated based on the data received from the passenger flow monitoring device 190, 195. This kind of approach may be based on detecting how many passengers enters and/or exits the elevator car 1 10 and using an average weight value for the passenger change it may be derived the estimation of the change in weight in the elevator car 110 by multiplying the change in the number of passengers in the elevator car 1 10 with the average weight value. Now, the estimation may be used for comparing it to a value representing a change of weight in the elevator car 110 wherein the value is determined from a plurality of consecutive measurement values received from the weighing device 180. The accuracy for the comparison may be selected in accordance with a need and in case it is detected that the compared values representing the change in the weight are with acceptable distance from each other, an indication may be generated 240 for indicating that the weighing device operates properly. If the values differ from each other more than is acceptable, an indication on the malfunctioning of the weighing device 250 may be generated.

For sake of clarity, it is worthwhile to mention that the data received from the weighing device 180 and the data received from the passenger flow monitoring device 190, 195 shall be comparable to each other so as the generated outcome from the detection 230 is reliable. This means that the pieces of data shall represent the same instant of time, or the time window. In accordance with an example embodiment, it may be arranged that the first data value from the weighing device 180 is obtained when the elevator car 1 10 lands in the landing whereas the second data value may be obtained when the elevator doors are instructed to close, and a difference between these two values may be determined, if any. Correspondingly, the data from the passenger flow monitoring device 190, 195 may be analyzed over the whole landing time in order to find out if any detection indicative of the passenger flow may be made during the landing. Naturally, any other time windows may be applied to as long as they are comparable to each other. In order to find the data used in the detection step 230 the measurement devices 180, 190, 195, or any other entities, may e.g. be configured to associate a time stamp to each measurement value so as to find data being comparable to each other i.e. to select values from the same time window.

Moreover, in case the result of the detection 230 is that it is indicated that the weighing device 180 operates properly, as referred with 240 in Figure 2, the monitoring of the operation of the weighing device 180 may be continued in a scheduled manner. On the other hand, if the outcome of the detection 230 indicates that the weighing device 180 malfunctions 250, it may be interpreted to reduce a safety of the elevator system 1000, and in accordance with at least one embodiment the elevator controller 170 may be configured to generate 260 a control signal to limit the use of the elevator in question. For example, the control signal may cause an opening of a safety circuit thus preventing a travel of the elevator car 1 10 from the landing in question. This may e.g. be achieved so that the control signal orders the elevator doors to stay open during which the safety circuit is open. In another approach the elevator may be set to a failure mode with the control signal which may prevent the use of the elevator. The failure mode may be indicated to the passengers through user interfaces of the elevator, such as over a car operating panel, COP. The indication on the situation, i.e. that the weighing device malfunctions, may also be delivered, as in a signal, to a service centre in order to receive maintenance for the elevator in question. Alternatively it may be arranged that the generated control signal causes that information on the detected situation, i.e. a mismatch in the operation between the weighing device 180 and the apparatus 190, 195, 197, may be delivered to the service centre in order to perform necessary maintenance measures, but the operation of the elevator system may be allowed to continue. Still further, it may be arranged that the measures taken due to the detection of the mismatch in the operation may be taken after a predefined number of independent detections of the mismatch in the operation are detected so that any temporal malfunction may be filtered out. Hence, the generation of the control signal 260 may cause a generation of a signal to update a value of a counter maintained to indicate detected malfunctions of the weighting device 180 from various analysis in the manner as described, and when the counter reaches a predefined reference value, the other above described measures may be taken.

Still further, in some example embodiments the evaluation of the operation of the weighing device 180, such as the comparison of the pieces of data from the different sources, may be triggered only when it is detected, based on the data received from the apparatus configured to generate data indicative of a passenger flow with respect to the elevator car 1 10 that the due to the passenger flow the load is really expected to change. Namely, it may occur that the same number of passengers enters the elevator car 1 10 as exits therefrom and in such a situation it may not be meaningful to evaluate an operational condition of the weighing device 180 since it may happen that no detection can be made due to unchanged, or essentially unchanged, weight. Hence, a predefined criterion for the change based on the information obtained from the apparatus 190, 195, 197 may be set to trigger the comparison of the pieces of data. For example, it may be set as the criterion that a change in the elevator car 1 10 in passengers is at least one passenger which may then be detected also in the value provided by the weighing device 180.

As discussed in the foregoing description the apparatus suitable for performing the operation according to the invention may be an elevator controller as referred with a reference 170 in Figure 2. An example of the apparatus is schematically illustrated in Figure 3 which may be configured to implement the present invention at least in part. In other words, the apparatus of Figure 3 may e.g. be configured to perform a function of an elevator controller 170 as described so as to control of a safety of an elevator system 1000. For sake of clarity, it is worthwhile to mention that the block diagram of Figure 3 depicts some components of an entity that may be employed to implement a functionality of the apparatus. The apparatus comprises a processor 310 and a memory 320. The memory 320 may store data, such pieces of data as described, but also computer program code 325 causing the control of the safety of the elevator system 1000 in the described manner. The apparatus may further comprise a communication interface, such as a wireless communication interface or a communication interface for wired communication, or both to communicate with other entities of the elevator system 1000. The communication interface 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 310. Furthermore, I/O (input/output) components may be arranged, together with the processor 310 and a portion of the computer program code 325, 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 out-put 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 320 and a portion of the computer program code 325 stored therein may further be arranged, with the processor 310, to cause the apparatus to perform at least a portion of a method for controlling the safety of the elevator system 1000 as is described herein. The processor 310 may be configured to read from and write to the memory 320. Although the processor 310 is depicted as a respective single component, it may be implemented as respective one or more separate processing components. Similarly, although the memory 320 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 I semipermanent I dynamic I cached storage.

The computer program code 325 may comprise computer-executable instructions that implement functions that correspond to steps implemented in the controlling of the safety of the elevator system 1000 when loaded into the processor 310 of the controller 150. As an example, the computer program code 325 may include a computer program consisting of one or more sequences of one or more instructions. The processor 310 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 320. The one or more sequences of one or more instructions may be configured to, when executed by the processor 310, cause the apparatus to perform a method as described. Hence, the apparatus may comprise at least one processor 310 and at least one memory 320 including the computer program code 325 for one or more programs, the at least one memory 320 and the computer program code 325 configured to, with the at least one processor 310, cause the apparatus to perform the method.

The computer program code 325 may be provided e.g. a computer program product comprising at least one computer-readable non-transitory medium having the computer program code 325 stored thereon, which computer program code 325, when executed by the processor 310 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 325 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 may also be implemented with a plurality of apparatuses, such as the one schematically illustrated in Figure 3, as a distributed computing environment corresponding to a control system. For example, one of the apparatuses may be communicatively connected with other apparatuses, and e.g. share the data of the method, to cause another apparatus to perform at least one portion of the method. As a result, the method performed in the distributed computing environment generates the detection result as described.

Some aspects of the invention may relate to an elevator system comprising the entities as described and configured to implement the method as described in the foregoing description.

For sake of completeness it may be mentioned that the weight of the load in the elevator car 110 may be expressed as an absolute weight or as a proportion with respect to a certain reference value, such as to a maximum load. In accordance with any of the implementation of providing information on the weight of the load it is possible to determine a correlation of the change in weight between the two sources of data, as described in the foregoing description.

The present invention, as an alternative solution, provides advantages over the known solutions. This is because the present invention primarily applies to existing devices in the elevators, such as a camera, a light curtain, or a similar, which allows a control of costs, or to minimize them, since there is no need to introduce additional devices, such as in the prior art solutions in which the weighing system is doubled.

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.