TECHNICAL FIELD

The invention concerns in general the technical field of conveyor systems. More particularly, the invention concerns a monitoring solution for conveyor systems.

BACKGROUND

Conveyor systems, such as elevators and the like, are under heavy use and the systems comprise components and sub-systems which are subject to wearing and breaking. In order to avoid down-time of the conveyor system there is developed a plurality of monitoring solutions for detecting, preferably in advance, if certain component and/or sub-system needs to be replaced. Such solutions are typically based on performing detections from a measurement data representing either directly or indirectly operational condition of the respective entity which measurement data is obtained with applicable sensors, or example. Naturally, visual inspection may be needed at regular intervals to make an overall checking of the conveyor system as well as any maintenance work if any.

The sensors used for monitoring solutions of the conveyor systems are typically such which are suitable for measuring some electrical value, such as a voltage or a current, at certain locations of the conveyor system. Furthermore, strain gauges may be used for measuring an elongation of an elevator rope. Hence, the conveyor systems are monitored in a plurality of ways in order to maintain the conveyor system operational.

Another issue is that there are aspects, such as operational conditions, which may be detected at least in part on a basis of scent. Typically, a technician when entering a location of the conveyor system may detect, during a normal inspection that the conveyor system does not operate properly due to scent detected at the site. Hence, there is a possibility to introduce further solutions for monitoring a conveyor 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 a conveyor system, a method, a control unit, and a computer program product for monitoring an operation of the conveyor system.

The objects of the invention are reached by a conveyor system, a method, a control unit, and a computer program product as defined by the respective independent claims.

According to a first aspect, a conveyor system is provided, the conveyor system comprising: at least one sensor associated to the conveyor system, the at least one sensor configured to generate measurement data indicative of a molecular concentration in air in an operational space of the at least one sensor; a control unit configured to receive measurement data from the at least one sensor, the control unit configured to: generate a pattern in accordance with the received measurement data indicative of the molecular concentration in air in the operational space of the at least one sensor; compare at least a portion of the generated pattern to at least one reference pattern; generate, in accordance with the comparison between the at least the portion of the generated pattern and the at least one reference pattern, a detection result to express one of the following: I) the conveyor system operates properly, II) the conveyor system malfunctions.

The conveyor system may comprise a machinery into which the at least one sensor is associated to. For example, the at least one sensor may be associated to a frame structure of the machinery so that it is arranged to receive air flowing below the machinery. Alternatively or in addition, the at least one sensor may be arranged in a vicinity of at least one bearing of the machinery to detect a leakage of a lubricant from the bearing.

The at least one sensor may further be arranged to at least one pulley along which at least suspension rope of a hoisting system of the conveyor system is arranged to travel to monitor a condition of the hoisting system.

For example, the control unit may be configured to generate the pattern as a frequency spectrum based on the measurement data.

The reference pattern may be generated by one of: defining a level for at least one molecular concentration mathematically for the reference pattern; defining a level for at least one molecular concentration based on at least one previous measurement for the reference pattern.

Also, the control unit may be configured to transmit the generated detection result to data center arranged to monitor the conveyor system.

Still further, the control unit belonging to the conveyor system may further be configured to: receive measurement data from at least one of the following: a thermometer residing in the operational space of the at least one sensor, a moisture meter residing in the operational space of the at least one sensor; select the reference pattern for the comparison in accordance with the received measurement data from the at least one of the following: a thermometer residing in the operational space of the at least one sensor, a moisture meter residing in the operational space of the at least one sensor. The conveyor system may be an elevator system.

According to a second aspect, a method for monitoring a conveyor system is provided, the method performed by a control unit comprises: receiving measurement data from the at least one sensor; generating a pattern in accordance with the received measurement data indicative of the molecular concentration in air in an operational space of the at least one sensor; comparing at least a portion of the generated pattern to at least one reference pattern; generating, in accordance with the comparison between the at least the portion of the generated pattern and the at least one reference pattern, a detection result to express one of the following: i) the conveyor system operates properly, ii) the conveyor system malfunctions.

The pattern may e.g. be generated as a frequency spectrum.

Further, the reference pattern may be generated by one of: defining a level for at least one molecular concentration mathematically for the reference pattern; defining a level for at least one molecular concentration based on at least one previous measurement for the reference pattern.

Still further, the method may further comprise: receiving measurement data from at least one of the following: a thermometer residing in the operational space of the at least one sensor, a moisture meter residing in the operational space of the at least one sensor; selecting the reference pattern for the comparison in accordance with the received measurement data from at least one of the following: a thermometer residing in the operational space of the at least one sensor, a moisture meter residing in the operational space of the at least one sensor.

According to a third aspect, a control unit for monitoring a conveyor system is provided, the control unit may be configured to perform the method according to the second aspect as defined above. According to a fourth aspect, a computer program product for monitoring a conveyor system is provided which, when executed by at least one processor, cause a control unit to perform the method 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.

Figure 1 illustrates schematically a conveyor system according to an example.

Figure 2 illustrates schematically a sensor according to an example shown from a first perspective.

Figure 3 illustrates schematically a sensor according to an example shown from a first perspective. Figures 4A and 4B illustrate schematically pattern representations of measurement data as an example.

Figure 5 illustrates schematically a method according to an example.

Figure 6 illustrates schematically a machinery of an elevator system according to an example.

Figure 7 illustrates schematically a control unit 130 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 1 illustrates schematically an example of a conveyor system 100 configured to implement the present invention. The conveyor system 100 may comprise a number of entities suitable for monitoring an operation of the conveyor system in accordance with the present invention. At least one requirement for such an entity being applicable for monitoring is that it generates one or more molecules which may be detected with at least one sensor 120 associated to the respective entity 110 of the conveyor system 100 wherein the generated molecules are indicative of an operational condition of the respective entity 110. In other words, the molecules may be detected as a consequence of a normal operation of the entity 110 under monitoring or be a consequence of some malfunction of the entity 110, and, thus, of the conveyor system 100. The measurement data obtained with the at least one sensor 120 may be delivered to a control unit 130 either automatically or by downloading it from the at least one sensor 120 in accordance with a predefined downloading scheme. The conveyor system 100 may also comprise one or more additional sensors arranged e.g. to generate measurement data indicative of an environment the sensor 120 measuring a molecular concentration of a number of the molecules in the space. The additional sensors are referred with 140 in Figure 1 and may e.g. correspond to a thermometer and/or to a moisture meter. The control unit 130 may refer to an entity residing at the site the conveyor system 100 or it may reside remotely e.g. in a data center. In some example embodiments the control unit 130 may be implemented as a distributed computing environment in which operations are divided between a plurality of physical entities e.g. residing at different locations. Naturally, there is arranged a communication connection between the respective entities in a manner that allows a communication between the entities as needed.

The sensor 120 applicable in the context of the present invention is such that it may provide measurement data indicative of scent within an operational space of the sensor 120. In other words, the sensor 120 arranged in its measurement space receives molecules representing one or more scents and is configured to generate a signal carrying measurement data for further analysis. For example, the sensor 120 may be implemented so that it is configured to receive a number of predefined molecules in a sensor array comprising a number of areas suitable for receiving different molecules. An example of such a sensor array is schematically illustrated in Figure 2 as a sideview wherein the sensor 120 comprises two sub-sections 120A, 120B implemented e.g. as a membrane structure each of which are configured to receive molecules of a specific type. The corresponding sensor is shown from a 3-dimensional perspective in Figure 3. In other words, a first sub-section 120A may be configured to receive first molecules (referred with A in Figure 2) whereas a second sub-section 120B may be configured to receive second molecules (referred with B in Figure 2) which may be defined by selecting the receptor membrane to correspond the molecules under interest in the application area. The receipt of the molecules may e.g. be achieved by arranging receptors having a shape suitable for receiving the desired molecule in the receptor, and preferably so that no other molecules suit the respective receptors. This is shown in Figure 2 so that the receptors of the first sub-section 120A have a cubical shape corresponding to the shape of first molecules A whereas the receptors of the second sub-section 120B have a spherical shape corresponding to the shape of the second molecules B. Accordingly, molecules of different shapes stick on the receptor in a different manner so that certain molecules match better with a certain receptor than with another. The operation of the membranes may be based on other approaches than to one based the shape of the molecules. Hence, by collecting the molecules from the air to the receptors and, since the first and second molecules may be considered as molecules having a scent characteristic to the molecule, it is possible to generate an output signal being indicative of a scent in the space of the sensor 120. For example, the sensor 120 may be arranged to generate an output signal indicating as changes in frequency in a vibration of the membrane in accordance with an amount of molecules in the receptors, i.e. on the membrane, of the sensor 120. For example, the sensor 120 may operate so that the molecules with high chemical affinity to the membrane of the sensor 120 change a mass of the membrane which has impact on the vibration, and, hence, may be detected from the frequency spectrum. In other words, a hit of the molecule to the receptor membrane may be determined from the output signal of the sensor. Naturally, molecules of the air generate a background noise in the output signal, but the molecules under interest may be detected from the output signal as deviations from the background noise from the spectrum outputted from the sensor 120. For sake of completeness, it is worthwhile to mention that in accordance with some example embodiments the sensor 120 may be implemented so that it comprises only such receptors in the sensor array, which are suitable for receiving molecules of an interest in the space where the sensor 120 is associated to. Furthermore, the number and type of receptors may be selected in accordance with the molecules of interest in the application area.

In response to a receipt of the measurement data as the output signal from the sensor 120 the control unit 130 may be configured to generate a pattern in accordance with the received measurement data representing indicative of a molecular concentration in air at an operational space of the at least one sensor. In other words, the measurement data carries, e.g. expressed as changes in the frequency of the output signal, data indicative of the amount of molecules in the receptors of the sub-sections 120A, 120B of the sensor 120 which is dependent on the molecular concentration in the air. Based on the measurement data the control unit 130 may be configured to generate a pattern in accordance with the received measurement data being indicative of the molecular concentration in the air at an operational space of the at least one sensor 120. The pattern may refer to a representation indicating amounts of molecules in the number of subsections 120A, 120B of the sensor 120. As mentioned, the pattern representation may be a frequency spectrum representing detections by the number of sub-sections 120A, 120B of the sensor 120. Figure 4A illustrates schematically an example of such as frequency spectrum wherein the detections are depicted as amplitudes over the spectrum range. As shown in a non-limiting manner in Figure 4A the air in accordance with the environment generates a background noise from which deviations may be detected and interpreted as deviating scents (cf. scent 1 and scent 2 in Figure 4A) from the background scents. According to some examples, the frequencies representing the deviations may be received from different sub-sections 120A, 120B of the sensor 120, or from the same sub-section 120A, 120B, or any combination of these if there are a greater number of sub-sections 120A, 120B than two. Moreover, the pattern representation disclosed in Figure 4A may be transformed to another type of representation being e.g. more indicative of the result of the detections as shown in Figure 4B. In Figure 4B a first pattern 410 may be considered to represent the amount of molecules in the first sub-section 120A representing e.g. scent 1 of Figure 4A whereas a second pattern 420 may be considered to represent the amount of molecules in the second sub-section 120B representing e.g. scent 2 of Figure 4A. A respective pattern representation may be generated from sensor array having a different number, i.e. less or more, of sub-sections. Naturally, the pattern representation is defined with digital data, such as with a matrix comprising a number of data values.

In response to the generation of the pattern representation the control unit 130 may be configured to compare the generated pattern to at least one reference pattern. The reference pattern may refer to a representation corresponding to a scenario possible at the space of the sensor 120 is mounted to. Alternatively or in addition, the reference pattern may refer to a pattern generated during a normal operation of the conveyor system in the space i.e. when the conveyor system operates as it shall. Furthermore, the reference pattern, or patterns, may be some sort of statistical derivation from previous measurement data. In other words, it defines a possible scent environment, or changes, in the space of the sensor 120. By having a plurality of reference patterns for the comparison it is possible to determine, to at least some extent, the scent in the space of the sensor 120, and, hence, even changes therein by arranging that the reference pattern is derived by performing one or more measurements in the space. In accordance with some example embodiments the number of reference patterns accessible to the control unit 130 are defined so that they represent the scents under interest in the space of the sensor 120. For example, the reference patterns may be selected so that they represent a specific group of operational conditions of the conveyor system, or the entity under monitoring, such as malfunction states which may be detected on the basis of the scent represented in the manner as described. For sake of completeness, in accordance with some example embodiments the comparison may be performed only to some portions of the pattern generated from the measurement data. Naturally, the reference pattern defines only those portions under interest.

As mentioned, in some example embodiments the reference data may be generated from previous measurements. This may be implemented so that the control unit 130 is taught, e.g. by applying machine learning practices, to be aware normal patterns of the measurement data which may be set as reference patterns for the comparison. Hence, the control unit 130, and the measurement system as a whole, is set to monitoring mode, the reference data, or reference patterns, may be used in the monitoring in the described manner.

Finally, the control unit 130 may be configured to generate, in accordance with the comparison between the generated pattern and the reference pattern, a detection result to express one of the following: i) the conveyor system operates properly, ii) the conveyor system malfunctions. For example, if the reference patterns are defined so that they represent unallowable states of the conveyor system on the basis of the scent a detection result expressing that the conveyor system malfunctions may be generated if a match is found between the generated pattern and at least one of the reference patterns. The generation of the detection result may correspond to an arrangement in which the control unit 130 may be configured to generate a message defining at least the detection result in a predetermined manner, such as with one bit, and transmit the message to a predefined destination, such as to a data center. In some embodiments, the communication is optimized by arranging that the message is generated only if the detection result indicates that the conveyor system malfunctions, or that based on the detection result proactive maintenance actions shall be taken. In such a case it is possible to include e.g. the generated pattern in the message for further analysis e.g. in the data center. As already mentioned, the implementation of the control unit 130 may also be such that it corresponds to the data center itself and is configured to perform the operation as described. Moreover, the data center may generate, in accordance with the detection result, or any further analysis, maintenance orders to a maintenance order system which are then delivered to technicians. The maintenance orders may be included with information how the malfunction may be corrected, such as by replacing a bearing or by adding lubricant to a lubrication device providing lubricant to the suspension rope, for example.

For sake of clarity, the method for monitoring the conveyor system, and especially its operation, according to an example embodiment from a perspective of the control unit 130 is schematically illustrated in Figure 5. The method steps disclosed in Figure 5 are already described in the foregoing description and are the following:

510: Measurement data is received from at least one sensor 120 by the control unit 130. 520: A pattern is generated in accordance with the received measurement data being indicative of a molecular concentration in air at an operational space of the at least one sensor 120.

530: The control unit 130 is configured to compare the generated pattern to at least one reference pattern available for the comparison for the control unit 130.

540: The control unit 130 is configured to generate, in accordance with the comparison between the generated pattern and the at least one reference pattern, a detection result to express one of the following: i) the conveyor system operates properly, ii) the conveyor system malfunctions.

Next, some further aspects of the example embodiments of the present invention are discussed in an implementation in which the conveyor system is an elevator system. In elevator systems there is a number of entities 110 suitable for monitoring with the solution according to an example in a manner as described in the foregoing description. An example of an entity 1 10 of an elevator system which may be monitored by associating the sensor 120 with the elevator system is a machinery of the elevator system used for moving an elevator car upwards and downwards in an elevator shaft. More specifically, the sensor 120 may be configured so that it comprises a number of receptors for receiving molecules of a lubricant used in the machinery. For example, the lubricant may be used in at least one bearing of the machinery and by positioning the sensor 120 outside the bearing it is possible to detect if the bearing leaks the lubricant. In other words, the receptors of the sensor 120 may receive at least a portion of the leaked lubricant which may be detected from the output signal of the sensor 120 by comparing the pattern generated on the basis of the measurement data with a reference pattern defining a scent of the lubricant.

Another area of interest in the context of the elevator systems may be a hoisting system of the elevator system. The hoisting system may be considered to comprise at least one suspension rope and one or more pulleys comprising a traction sheave, diverters and the like for transmitting a power generated by the machinery to moving the elevator car in its path. The mentioned entities are wearing components which are e.g. subject to fretting wear as well as to groove wear of the pulley. The wearing of the mentioned entities may be avoided at least in part by lubricating the suspension rope and the other entities regularly. However, in order to monitor the operational condition of the hoisting system, and at least some of the mentioned entities of the elevator system, the at least one sensor may be arranged to at least one pulley along which at least suspension rope of the hoisting system of the conveyor system, such as the elevator system, is arranged to travel. In accordance with the implementation in the context of the elevator system, and specifically in the hoisting system, the sensor 120 may be configured to collect molecules of a lubricated suspension rope and if a level of the lubricant molecules decreases below a certain level, e.g. defined with the reference patterns, a detection result may be generated. Alternatively or in addition, a scent originating from a fretting rust may be detected from the measurement data when the sensor array comprises such a sub-section configured to collect the molecules defining the fretting rust.

Further locations for associating the sensor 120 may e.g. be an elevator brake wherein brake pads may generate a detectable scent especially if the brake pads are incorrectly adjusted and, thus, wearing abnormally. Hence, the sensor 120 may be associated in a vicinity of the elevator brake to receive molecules, or particles, generated during braking. The same applies with respect to hydraulic fluids in the brake systems whose leakage from the brake system may be detected on the basis of the scent in the described manner.

Further entities in the elevator systems in which lubricants detectable with the described sensor 120 are applied to are the guide rails. A presence of lubricants along the guide rails may be monitored by associating one or more sensors 120 along the guide rails, or in applicable positions in the elevator shaft, and by receiving measurement data therefrom. A decrease in the amount of the lubricant below a predefined level may be detected on the basis of the measurement data and a detection result may be generated accordingly. Still further, by arranging sensor 120 in an elevator machine room or in an elevator shaft, the sensor 120 comprising a sub-section configured to receive vapor, i.e. water molecules, and/or smoke particles it is possible to detect any malfunction due to mentioned substances in the respective spaces.

In view of the foregoing description Figure 6 illustrates at least some aspects of the present invention in an implementation in which an elevator system operates as the conveyor system. More specifically, Figure 6 illustrates schematically at least some portions of a machinery of the elevator system wherein the hoisting system is implemented in a frame structure 610 wherein a traction sheave 620 is arranged to rotate around an axis 640 with a bearing implementation to reduce friction. The bearings may be filled with the lubricant as already mentioned. Moreover, an elevator rope, i.e. as suspension rope or belt, is arranged to run around the traction sheave 620 and by rotating the traction sheave with electric motor the elevator car may be achieved to move in the shaft. Further, the machinery may comprise elevator brakes 650 so as to allow a control of a motion of the traction sheave 620. An example of the positioning of the sensor 120 is schematically illustrated in Figure 6. Namely, the sensor 120 may advantageously be associated so that it resides in a position receiving air carrying the molecules generated by the elevator system, or machinery, of the interest. Due to operation of the machinery an advantageous position the sensor 120 may be associated, or mounted, to may be the frame structure 610 and below the rotating entities of the machinery, such as the traction sheave 620. The air from the machinery flows below the structure and, hence, carries the molecules thereto allowing a measurement with the sensor 120. The sensor 120 may reside on an inner surface of the frame structure 610 or on an outer surface of the frame structure 610 (as shown in Figure 6). The inner surface refers to the portion of the frame structure facing towards the rotating entities. In some example embodiments, the sensor 120 may be associated to a floor below the machinery. Generally speaking, the association shall be made so that the sensor 120 receives a necessary amount of air possibly carrying molecules from the entity under monitoring. As mentioned, a condition of the bearings, a condition of the pulleys, such as the traction sheave 620, or a condition of the rope 630 may be detected as some non-limiting examples. In addition to the mentioned entities, a monitoring of at least some electrical component may be arranged by selecting such a sensor 120 which comprises at least one sub-section 120A, 120B for receiving molecules generated if a resin used for protecting electrical components burn.

For example, a control unit 130 suitable for performing at least part of the method as described may refer to an apparatus being a computing device, such as a server device, or any similar data processing device, as schematically illustrated in Figure 7 as a non-limiting example. For sake of clarity, it is worthwhile to mention that the block diagram of Figure 7 depicts some components of an entity that may be employed to implement an operation of the control unit 130. The apparatus comprises a processor 710 and a memory 720. The memory 720 may store data, such as comparison data, and computer program code 725. The apparatus may further comprise communication means 730 for wired and/or wireless communication with other entities. Furthermore, I/O (input/output) components may be arranged, together with the processor 710 and a portion of the computer program code 725, 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 display or a touchscreen. The components of the apparatus may be communicatively coupled to each other via data bus that enables transfer of data and control information between the components.

The memory 720 and a portion of the computer program code 725 stored therein may further be arranged, with the processor 710, to cause the apparatus, i.e. the device, to perform at least a portion of the method as described in the foregoing description in relation to Figure 5. The processor 710 may be configured to read from and write to the memory 720. Although the processor 710 is depicted as a respective single component, it may be implemented as respective one or more separate processing components. Similarly, although the memory 720 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 / semipermanent / dynamic / cached storage.

The computer program code 725 may comprise computer-executable instructions that implement functions that correspond to steps of the method when loaded into the processor 710. As an example, the computer program code 725 may include a computer program consisting of one or more sequences of one or more instructions. The processor 710 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 720. The one or more sequences of one or more instructions may be configured to, when executed by the processor 710, cause the apparatus to perform the method as described herein. Hence, the apparatus may comprise at least one processor 710 and at least one memory 720 including the computer program code 725 for one or more programs, the at least one memory 720 and the computer program code 725 configured to, with the at least one processor 710, cause the apparatus to perform the method as described.

The computer program code 725 may be provided e.g. a computer program product comprising at least one computer-readable non-transitory medium having the computer program code 725 stored thereon, which computer program code 725, when executed by the processor 710 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 725 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 firm-ware or hardware adapted to or programmed to perform the necessary tasks.

As mentioned, the entity performing the method may also be implemented with a plurality of apparatuses, such as the one schematically illustrated in Figure 7, as a distributed computing environment. For example, one of the apparatuses may be communicatively connected to a number of sensors 120 and, hence, receive the measurement data from the sensors 120. Subsequently, the apparatus may be arranged to communicate with other apparatuses, and e.g. share the measurement data to cause another apparatus to perform at least one portion of the method. As a result, the method performed in the shared computing environment generates the detection result as described.

In accordance with some example embodiments the operation of the solution as described may be improved by defining a variety of reference patterns in accordance at least one of: temperature in the environment the number of sensors 120 are positioned to, moisture of the air in the environment the number of sensors 120 are positioned to. In other words, there may be defined a plurality of reference patters each of which is dedicated to being applied in accordance with either the temperature or the moisture or both. In order to select a correct reference pattern the control unit 130 may be arranged to receive a measurement value from an applicable source, such as from the additional sensors 140 like a thermometer residing in the space or from a moisture meter residing in the space or from both, so as the select the reference pattern to be applied to in the comparison 530. For example, the control unit 130 may inquire the reference pattern from data storage with an inquiry having the respective measurement value as a parameter in the inquiry. The data storage selects, based on the measurement value, the reference pattern to be applied in the comparison and returns it to the control unit 130. This kind of arrangement may e.g. be implemented so that a certain reference pattern is applicable to a predefined range of the respective at least one parameter, such as the temperature or the moisture or both. The receipt of the measurement data from at least one of the mentioned additional sensors may be implemented as a continuous operation or triggered e.g. in response to a receipt of data from the sensor 120 measuring the molecular concentration. This approach may be applied with any of the example embodiments described in the foregoing description.

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.