Patent Publication Number: US-2022212896-A1

Title: Door sensor unit and a method for determining a type of a door

Description:
TECHNICAL FIELD 
     The invention concerns in general the technical field of doors. Especially the invention concerns monitoring of doors. 
     BACKGROUND 
     Elevators and buildings may have different type of doors. Some examples of the different types of doors may be horizontally moving doors, vertically moving doors, swing doors, folding doors, etc.. Typically, the elevators have landing doors on each landing and a car door on the elevator car. The doors of the elevators are typically horizontally moving automatic doors. The horizontally moving automatic doors of the elevators may be either center, left or right opening. Alternatively or in addition, for example the landing doors of the elevators may be swing doors and/or the car doors of the elevators may be folding doors. Moreover, elevator, especially elevators intended for conveying freight, may have vertically moving doors. 
     A sensor-based condition monitoring, preferably remote monitoring, may be applied to any type doors. Typically, the condition monitoring of the doors may be based on accelerometer-based sensor solutions. In swing doors also gyroscope-based sensor solutions may be used. In order to be able to monitor the condition of the door it may be necessary to identify when the door is opening and when the door is closing. In the accelerometer-based sensor solutions the identification of the door opening and closing typically comprises using a model, e.g. an algorithm, for detecting the direction of the movement of the door, e.g. direction of the acceleration of the door. 
     Because the motion of each type of door is different, the model for detecting the direction of the movement of the door is specific for each door type. Thus, the door sensors are typically tailored for each door type by using the door type specific model. Even though the model may be made substantially generic with respect to door size and speed, the direction of the movement needs to be defined by using the door type specific model. 
     Thus, there is need to develop further solutions for sensor-based condition monitoring of doors. 
     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 objective of the invention is to present a door sensor unit and a method for determining a type of a door. Another objective of the invention is that the door sensor unit and the method for determining a type of a door enables monitoring of different type of doors. 
     The objectives of the invention are reached by a door sensor unit and a method as defined by the respective independent claims. 
     According to a first aspect, a door sensor unit for determining a type of a door to which the door sensor unit is attached is provided, wherein the door sensor unit is configured to: obtain movement data representing movement of the door during a learning period, and determine the type of the door based on the obtained movement data. 
     The determination of the type of the door may comprise a first determination phase and a second determination phase. 
     The first determination phase may comprise that the door sensor unit is con figured to: input the obtained movement data into a plurality of door type specific models to generate a movement pattern of each of the plurality of door type specific model, compare the generated movement pattern of each of the plurality of door type specific model to predefined movement patterns of the door, rate the movement patterns of the plurality of door type specific models based on the comparison, and select a group of door type specific models based on the ratings of the movement patterns of the plurality of door type specific models. 
     The predetermined movement patterns may comprise a plurality of elevator car door movement patterns representing movement of an elevator car followed by opening and dosing movement of the door or opening and dosing movement of the door followed by movement of an elevator car and a plurality of building/landing door movement patterns representing opening and dosing movement of the door. 
     Alternatively or in addition, the second determination phase may comprise that the door sensor unit is configured to: detect one or more directions of the movement representing movement of the door in each movement pattern of the selected group of door type specific models, select a winning door type specific model, and determine the type of the door based on the detected one or more directions of the movement of movement pattern of the of the winning door type specific model. 
     In response to detection of: only vertical direction, the type of the door may be determined to be a vertically moving door; only horizontal direction, the type of the door may be determined to be a horizontally moving door; direction normal to a vertical plane, the type of the door may be determined to be a swing door; or horizontal direction and direction normal to a vertical plane, the type of the door may be determined to be a folding door. 
     Alternatively or in addition, the learning period may comprise at least one movement cycle, wherein in case of an elevator car door one movement cycle may comprise movement of an elevator car followed by opening and closing movement of the door or opening and closing movement of the door followed by movement of an elevator car, and in case of a building/landing door one movement cycle may comprise opening and closing movement of the door. 
     Alternatively or in addition, the door sensor unit may comprise an accelerometer configured to obtain the movement data of the door, wherein the movement data may be three-dimensional acceleration of the door. 
     According to a second aspect, a method for determining a type of a door is provided, wherein the method comprises: obtaining movement data representing movement of the door during a learning period, and determining the type of the door based on the obtained movement data. 
     The step of determining the type of the door may comprise a first determination phase and a second determination phase. 
     The first determination phase may comprise: inputting the obtained movement data into a plurality of door type specific models to generate a movement pattern of each of the plurality of door type specific model, comparing the generated movement pattern of each of the plurality of door type specific model to predefined movement patterns of the door, rating the movement patterns of the plurality of door type specific models based on the comparison, and selecting a group of door type specific models based on the ratings of the movement patterns of the plurality of door type specific models. 
     The predetermined movement patterns may comprise a plurality of elevator car door movement patterns representing movement of an elevator car followed by opening and closing movement of the door or opening and closing movement of the door followed by movement of an elevator car and a plurality of building/landing door movement patterns representing opening and closing movement of the door. 
     Alternatively or in addition, the second determination phase may comprise: detecting one or more directions of the movement representing movement of the door in the movement patterns of the selected group of door type specific models, selecting a winning door type specific model, and determining the type of the door based on the detected one or more directions of the movement of movement pattern of the of the winning door type specific model. 
     In response to detection of: only vertical direction, the type of the door may be determined to be a vertically moving door; only horizontal direction, the type of the door may be determined to be a horizontally moving door; direction normal to a vertical plane, the type of the door may be determined to be a swing door; or horizontal direction and direction normal to a vertical plane, the type of the door may be determined to be a folding door. 
     Alternatively or in addition, the learning period may comprise at least one movement cycle, wherein in case of an elevator car door one movement cycle may comprise movement of an elevator car followed by opening and closing movement of the door or opening and closing movement of the door followed by movement of an elevator car and in case of a building/landing door one movement cycle may comprise opening and closing movement of the door in case of a building/landing door. 
     Alternatively or in addition, the movement data may be three-dimensional acceleration of the door obtained by an accelerometer. 
     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. 
         FIGS. 1A-1D  illustrate schematically examples of a door sensor unit according to the invention. 
         FIG. 2  illustrates schematically an example of components of a door sensor unit according to the invention. 
         FIG. 3  illustrates schematically an example of a method according to the invention. 
         FIGS. 4-6  illustrate schematically more detailed examples of the method according to the invention. 
     
    
    
     DESCRIPTION OF THE EXEMPLIFYING EMBODIMENTS 
       FIGS. 1A-1D  illustrate schematically examples of a door sensor unit  100  according to the invention arranged to different type of doors  102 .  FIGS. 1A, 1C, and 1D  illustrate a top view of the door  102  to which the door sensor unit  100  is arranged and  FIG. 1B  illustrates a front view of the door  102  to which the door sensor unit  100  is arranged. In  FIGS. 1A-1D  the direction of the Y-axis is the horizontal direction, the direction of the Z-axis is the vertical direction, and the direction of X-axis is the direction normal, i.e. perpendicular, to the vertical plane, i.e. YZ-plane. The door sensor unit  100  may be arranged, i.e. attached or mounted, to any part of the door  102  which is moving along with the door  102 , when the door  102  is opening and closing, According to a non-limiting example, the door sensor unit  100  may be arranged to a door panel, i.e. door leaf, of the door  102 . Some non-limiting examples to arrange, i.e. to attach or mount, the door sensor unit  100  to the door  102  may comprise for example a double-sided tape, a magnet-based attachment, or any other known attachment means suitable for arranging the door sensor unit  100  to the door  102 .  FIGS. 1A-1D  illustrate some non-limiting example locations to which the door sensor unit  100  according to invention may be arranged. The door sensor unit  100  according to the invention is configured to determine the type of the door  102  to which the door sensor unit  100  is attached. The door sensor unit  100  according to the invention may determine a high-level type of the door  102 , i.e. equipment-based type of the door  102 , and a sub-level type of the door  102 , i.e. a detailed type of the door  102 . In other words, the door sensor unit  100  may first determine the high-level type of the door  102  and after the determination of the high-level type  102  the door sensor unit  100  may determine the sub-level type of the door  102 . The high-level type of the door  102  may be an elevator car door or a building/landing door. The sub-level type of the door  102  may be e.g. a horizontally moving door (either center opening, left opening, or right opening), a vertically moving door, a swing door, or a folding door.  FIG. 1A  illustrates a non-limiting example of an elevator car door  102 , i.e. a door  102  of an elevator car  104 , to which the door sensor unit  100  according to the invention may be arranged. The elevator car door  102  of the example of  FIG. 1A  is a horizontally moving door (the arrows in  FIG. 1A  illustrate the opening direction of the door panels of the door  102 ). More specifically, the elevator car door  102  of the example of  FIG. 1A  is a center opening horizontally moving elevator car door  102 .  FIG. 1B  illustrates a non-limiting example of a building/landing door  102  to which the door sensor unit  100  according to the invention may be arranged. The building/landing door  102  of the example of  FIG. 1B  is a vertically moving landing door (the arrow in  FIG. 1B  illustrates the opening direction of the door  102 ).  FIG. 1C  illustrates a non-limiting example of a building/landing door to which the door sensor unit  100  according to the invention may be arranged. The building/landing door  102  of the example of  FIG. 10  is a swing door (the arrow in  FIG. 1C  illustrates the opening direction of the door  102 ).  FIG. 1D  illustrates a non-limiting example of a building/landing door to which the door sensor unit  100  according to the invention may be arranged. The building/landing door  102  of the example of  FIG. 1D  is a folding door (the arrows in  FIG. 1D  illustrate the opening direction of the door panels of the door  102 ). In the example of 
       FIG. 1D  a single sided folding door is illustrated, but the door  102  may also be a double-sided folding door. 
     The door sensor unit  100  according to the invention is configured to obtain movement data representing movement of the door  102  during a learning period. The movement data may be e.g, an acceleration of the door  102  and/or a speed of the door  102 . The door sensor unit  100  may comprise an accelerometer  250  configured to obtaining the movement data of the door  102 . Preferably the accelerometer  250  may be a three-axis accelerometer configured to obtain movement data, wherein the movement data is three-dimensional, i.e. three-axis, acceleration of the door  102 . The learning period may comprise at least one movement cycle. Preferably the learning period comprises between 1 to 10 movement cycles. If the high-level type of the door  102  is the elevator car door one movement cycle may comprise movement of the elevator car  104  followed by opening and closing movement of the door  102  or opening and closing movement of the door  102  followed by a movement of the elevator car  104 . Alternatively, if the high-level type of the door  102  is the building/landing door one movement cycle may comprise opening and closing movement of the door  102 . 
     The door sensor unit  100  according to the invention is further configured to determine the type of the door  102  based on the obtained movement data. The determination of the type of the door  102  may comprise a first determination phase and a second determination phase. As a result of the first determination phase the high-level type of the door  102  may be determined. As a result of the second determination phase the sub-level type of the door  102  may be determined. In other words, the first determination phase may comprise a determination of the high-level type of the door  102 , i.e. whether the door  102  is an elevator door or a building/landing door, and the second determination phase may comprise a determination of the sub-level type of the door  102  may be determined, i.e, whether the door  102  is a horizontally moving door (either center opening, left opening, or right opening), a vertically moving door, a swing door, or a folding door. 
     The first determination phase, i.e. the determination of the high-level type of the door  102 , may comprise that the door sensor unit  100  is configured to input the obtained movement data into a plurality of door type specific models, i.e. algorithms, to generate a movement pattern of each of the plurality of door type specific model. In other words, the door sensor unit  100  may be configured to use the obtained movement data as input data of each of the plurality of door type specific models and a movement pattern is generated as output data of each of the plurality of door type specific models. For example, a memory unit  220  of the door sensor unit  100  may be configured to store the plurality of door type specific models. The plurality of door type specific models may comprise a door type specific model for each type of the door  102 , i.e. a plurality of door type specific models for the elevator car door and a plurality of door type specific models for the building/landing door. The plurality of door specific models for the elevator car door may comprise a door type specific model for each sub-level type elevator car door, e.g. a door type specific model of a center opening horizontally moving elevator car door, a door type specific model of a right opening horizontally moving elevator car door, a door type specific model of a left opening horizontally moving elevator car door, a door type specific model of a vertically moving elevator car door, a door type specifics model of a swing elevator car door, and/or a door type specific model of a folding elevator car door. The plurality of door specific models for the building/landing door may comprise a door type specific model for each sub-level type building/landing door, e.g. a door type specific model of a center opening horizontally moving building/landing door, a door type specific model of a right opening horizontally moving building/landing door, a door type specific model of a left opening horizontally moving building/landing door, a door type specific model of a vertically moving building/landing door, a door type specific model of a swing building/landing door, and/or a door type specific model of a folding building/landing door. 
     The first determination phase may further comprise that the door sensor unit  100  is configured to compare the generated movement pattern of each of the plurality of door type specific model to predefined movement patterns of the door  102 . The predetermined movement patterns of the door  102  may comprise a plurality of predefined elevator car door movement patterns and a plurality of predefined building/landing door movement patterns. Each of the plurality of predefined elevator car door movement patterns represents a movement of the elevator car  104  followed by opening and dosing movement of the door  102  or opening and closing movement of the door  102  followed by a movement of the elevator car  104 . Each of the plurality of predefined building/landing door movement patterns represents opening and closing movement of the door  102 . The plurality of predefined elevator car door movement patterns comprises a predefined movement pattern for each sub-level type elevator car door, e.g. a predefined movement pattern of a center opening horizontally moving elevator car door, a predefined movement pattern of a right opening horizontally moving elevator car door, a predefined movement pattern of a left opening horizontally moving elevator car door, a predefined movement pattern of a vertically moving elevator car door, a predefined movement pattern of a swing elevator car door, and/or a predefined movement pattern of a folding elevator car door. The plurality of predefined building/landing door movement patterns comprises a predefined movement pattern for each sublevel type building/landing door, e.g. a predefined movement pattern of a center opening horizontally moving building/landing door, a predefined movement pattern of a right opening horizontally moving building/landing door, a predefined movement pattern of a left opening horizontally moving building/landing door, a predefined movement pattern of a vertically moving building/landing door, a predefined movement pattern of a swing building/landing door, and/or a predefined movement pattern of a folding building/landing door, 
     The first determination phase may further comprise that the door sensor unit  100  is configured to rate the generated movement patterns of the plurality of door type specific models based on the comparison. The rating of the generated movement patterns of the plurality of door type specific models may e.g. 
     comprise rating the generated movement patterns of the plurality of door type specific models based on that how they match with, i.e. correspond to, the predefined movement patterns. The generated movement patterns of the door type specific models of different sub-types of the elevator car door may be considered to match substantially well with the predefined elevator car door movement patterns. Whereas the generated movement patterns of the door type specific models of different sub-types of the elevator car door may be considered to match substantially poorly with the predefined building/landing door movement patterns. Similarly, the generated movement patterns of the door type specific models of different sub-types of the building/landing door may be considered to match substantially well with the predefined building/landing door movement patterns. Whereas the generated movement patterns of the door type specific models of different sub-types of the building/landing door may be considered to match substantially poorly with the predefined elevator car door movement patterns. 
     The better a generated movement pattern matches with a predefined movement pattern, the higher rating said generated movement pattern may obtain, i.e. receive. In other words, the generated movement patterns of the door type specific models of the different sub-types of the elevator car door may obtain higher ratings when they are compared to the predefined elevator car door movement patterns than when they are compared to the predefined building/landing door movement patterns. Similarly, the generated movement patterns of the door type specific models of the different sub-types of the building/landing door may obtain higher ratings when they are compared to the predefined building/landing door movement patterns than when they are corm pared to the predefined elevator car door movement patterns. For example, if the door sensor unit  100  is arranged to an elevator car door, the generated movement patterns of door type specific models of the different sub-types of the elevator car door may be rated with a higher rating than the generated movements patterns of door type specific models of the different sub-types of the building/landing door. Alternatively, if the door sensor unit  100  is arranged to a building/landing door, the generated movement patterns of door type specific models of the different sub-types of the building/landing door may be rated with a higher rating than the generated movements patterns of door type specific models of the different sub-types of the elevator car door. 
     The first determination phase may further comprise that the door sensor unit  100  is configured to select a group of door type specific models based on the ratings of the generated movement patterns of the plurality of door type specific models. For example, if the door sensor unit  100  is arranged to an elevator car door, the door type specific models of the different sub-types of the elevator car door have higher rating than the door type specific models of the different sub-types of the building/landing door and thus the door type specific models of the different sub-types of the elevator car door may form the selected group of door type specific models. Alternatively, if the door sensor unit  100  is arranged to a building/landing door, the door type specific models of the different sub-types of the building/landing door have higher rating than the door type specific models of the different sub-types of the elevator car door and thus the door type specific models of the different sub-types of the building/landing door may form the selected group of door type specific models. In other words, the selected group determines the high-level type of the door  102 . If the selected group comprises door type specific models of the different sub-types of the elevator car door, the high-level type of the door  102  may be determined to be the elevator door. Alternatively, if the selected group comprises door type specific models of the different sub-types of the building/landing door, the high-level type of the door may be determined to be the building/landing door. 
     The first determination phase may further comprise a determination of a direction the gravity. Alternatively, the second determination phase may comprise the determination of the direction of the gravity. The determination of the direction of the gravity may comprise observing by the door sensor unit  100  a long-term average of the obtained movement data, e.g. the acceleration of the door  102 , or an instantaneous value of the obtained movement data, i.e. the acceleration of the door  102 , when the door  102  is determined to be still, i.e. when the accelerometer noise level is low. 
     The second determination phase, which may be performed after the first determination phase, i,e, after the determination of the high-level type of the door  102 , may comprise that the door sensor unit  100  is configured to detect one or more directions of the movement representing movement of the door  102  in each movement pattern of the selected group of the door type specific models. The detecting the one or more directions of the movement may comprise filtering the gravity out from the generated movement patterns of the selected group of the door type specific models. In addition, if the selected group comprises door type specific models of the different sub-types of the elevator car door, the detecting the one or more directions of the movement may comprise filtering the movement of the elevator car  104  out from the generated movement patterns of the selected group of the door type specific models. In other words, after filtering the gravity and the movement of the elevator car  104  out from the generated movement patterns of the selected group of the door type specific models, the remaining filtered movement patterns represents the opening and closing movement of the door  102  in the one or more directions depending on the door type specific model. 
     The second determination phase may further comprise that the door sensor unit  100  is configured to select a winning, i.e, an actual, door type specific model by comparing the filtered movement patterns of the selected group of the door type specific models to predefined movement patterns representing opening and dosing movement of sub-level door types. The door type specific model whose filtered movement pattern corresponds to the predefined movement pattern representing opening and dosing movement of one of the sublevel door type may be selected as the winning door type specific model, i.e. the door type specific model that corresponds to the sub-level type of the door  102  to which the door sensor unit  100  is arranged. 
     For example, in the predefined movement patterns of the horizontally opening door and the vertically opening door, when the door starts the opening movement, the movement of the door  102  accelerates to a certain speed, i.e. the speed of the door  102  changes from zero to a rated speed, which is driven during a predefined period of time before the movement of the door  102  starts to decelerate, preferably smoothly, into open position of the door  102 . Similarly, in the predefined movement patterns of the horizontally opening door and the vertically opening door, when the door starts the closing movement, the movement of the door  102  accelerates to the certain speed, i.e. the door  102  speed changes from zero to the rated speed, which is driven during the predefined period of time prior to the movement of the door  102  starts to decelerate, preferably smoothly, into closed position of the door  102 . The predefined movement patterns representing opening and closing movement of the swing door and folding door may typically be slightly more complicated, but the basic idea corresponds to the opening and closing movement of the horizontally and vertically opening doors. In the filtered movement patterns representing the opening and closing movement of the door  102 , the acceleration of the door  102 , i.e. the changes of the speed of the door  102 , may be detected in different directions depending on the door type specific model. The filtered movement pattern in which the acceleration, i.e. changes of the speed of the door  102 , follows, i.e. is similar to, the acceleration, i.e. changes of the speed of the door  102 , of the predefined movement pattern of one of the sub-level door type may be selected as the winning door type specific model of the selected group. 
     In addition, according to an example in case that the selected group comprises door type specific models of the different sub-types of the elevator car door, the movement of the elevator car  104  may further be utilized in the selection of the winning door type specific model, e.g. to define that the elevator car door  102  is closed, if the elevator car  104  is moving, and/or that the movement following the movement of the elevator car  104  is opening of the elevator car door  102 . 
     The second determination phase may further comprise that the door sensor unit  100  is configured to determine the type of the door  102 , i.e. sub-level type of the door  102 , based on the detected one or more directions of the movement of the winning door type specific model. In response to detection of only vertical direction movement, the type of the door  102 , i.e. the sub-level type of the door  102 , may be determined to be a vertically moving door. Alternatively, in response to detection of only horizontal direction movement, the type of the door  102 , i,e, the sub-level type of the door  102 , may be determined to be a horizontally moving door. Alternatively, in response to detection of movement having direction normal to a vertical plane, the type of the door  102 , i.e. the sub-level type of the door  102 , may be determined to be a swing door. Alternatively, in response to detection of horizontal direction movement and movement having direction normal to a vertical plane, the type of the door  102 , i.e. the sub-level type of the door  102 , may be determined to be a folding door. 
     The door sensor unit  100  may be configured to use, i.e. apply, for the subsequent operation after the learning period, e.g. for condition monitoring of the door  102 , the door type specific model of the determined type of the door  102 , i.e. the winning door type specific model. The capability of the door sensor unit  100  according to the invention to determine the type of the door  102  enables that the door sensor unit  100  according to invention may be arranged to all type doors for condition monitoring, preferably remote monitoring, of said door  102  regardless of the type of the door  102 . In other words, the capability of the door sensor unit  100  to determine the type of the door  102  enables that the same door sensor unit  100  may be used for condition monitoring of different type of doors. Alternatively or in addition, the door sensor unit  100  according to the invention may adapt to different installation orientations based on the determined direction of the gravity. In other words, the door sensor unit  100  may be installed to the door  102  in any position irrespective of the installation orientation of the door sensor unit  100 . 
       FIG. 2  schematically illustrates an example of components of the door sensor unit  100  according to the invention. The door sensor unit  100  may comprise a processing unit  210  comprising one or more processors, a memory unit  220  comprising one or more memories, a communication unit  230  comprising one or more communication devices, possibly a user interface (UI) unit  240 , and the accelerometer  250 . The mentioned elements may be communicatively coupled to each other with e.g. an internal bus. The memory unit  220  may store portions of computer program code  225  and any other data, and the processing unit  210  may cause the door sensor unit  100  to operate as described above by executing at least some portions of the computer program code  225  stored in the memory unit  220 . The processing unit  210  of the door sensor unit  100  may also be at least configured to implement at least some method steps as will be described. The implementation of the method may be achieved by arranging the processing unit  210  to execute at least some portion of computer program code  225  stored in the memory unit  220  causing the processing unit  210 , and thus the door sensor unit  100 , to implement one or more method steps as will be described. The processing unit  210  is thus arranged to access the memory unit  220  and retrieve and store any information therefrom and thereto. Moreover, the processing unit  210  is configured to control the communication through the communication interface  230  with any external unit. The processing unit  210  may also be configured to control storing of received and delivered data. For sake of clarity, the processor herein refers to any unit suitable for processing information and control the operation of the door sensor unit  100 , among other tasks. The operations may also be implemented with a microcontroller solution with embedded software. Similarly, the memory unit  220  is not limited to a certain type of memory only, but any memory type suitable for storing the described pieces of information may be applied in the context of the present invention. The communication unit  230  may be based on one or more known communication technologies, either wired or wireless, in order to exchange pieces of information. The communication unit  230  provides an interface for communication any external units, any databases, and/or any external systems. The communication unit  230  may comprise one or more communication devices, e.g. radio transceiver, antenna, etc. The user interface  240  may comprise I/O devices, such as buttons, keyboard, touch screen, microphone, loudspeaker, display and so on, for receiving input and outputting information. 
     Above the invention is defined referring to the door sensor unit  100 , but the invention relates also to a method for determining the type of the door  102 . Next an example of the method according to the invention is described by referring to  FIG. 3 .  FIG. 3  schematically illustrates the invention as a flow chart. 
     At a step  310  the door control unit  100  obtains movement data representing movement of the door  102  during the learning period as described above. The movement data may be e.g. an acceleration of the door  102  and/or a speed of the door  102 . Preferably, the movement data may be three-dimensional, i.e. three axis, acceleration of the door  102  obtained by the accelerometer, i.e. a three-axis accelerometer,  250  of the door control unit  100 . 
     At a step  320  the door sensor unit  100  further determines the type of the door  102  based on the obtained movement data as described above. The determination of the type of the door  102  at the step  320  may comprise a first determination phase  410  and a second determination phase  420 . The second determination phase  420  may be performed after the first determination phase  410 . 
       FIG. 4  schematically illustrates the determination step  320  of  FIG. 3  in more detailed manner. As a result of the first determination phase  410  the high-level type of the door  102  may be determined as described above. As a result of the second determination phase  420  the sub-level type of the door  102  may be determined as described above. 
       FIG. 5  schematically illustrates the first determination phase  410 , i.e. the determination of the high-level type of the door  102 , of the determination step  320  in more detailed manner. At a step of  510  of the first determination step  410  the door sensor unit  100  inputs the obtained movement data into a plurality of door type specific models, i.e, algorithms, to generate a movement pattern of each of the plurality of door type specific model. In other words, the door sensor unit  100  may use the obtained movement data as input data of each of the plurality of door type specific models and a movement pattern is generated as output data of each of the plurality of door type specific models. The plurality of door type specific models may comprise a door type specific model for each type of the door  102 , i.e. a plurality of door type specific models for the elevator car door and a plurality of door type specific models for the building/landing door. The plurality of door specific models for the elevator car door may comprise a door type specific model for each sub-level type elevator car door as discussed above. The plurality of door specific models for the building/landing door may comprise a door type specific model for each sublevel type building/landing door as discussed above. 
     At a step of  520  of the first determination step  410  the door sensor unit  100  may compare the generated movement pattern of each of the plurality of door type specific model to predefined movement patterns of the door  102 . The predetermined movement patterns of the door  102  may comprise a plurality of predefined elevator car door movement patterns and a plurality of predefined building/landing door movement patterns. Each of the plurality of predefined elevator car door movement patterns represents a movement of the elevator car  104  followed by opening and dosing movement of the door  102  or opening and dosing movement of the door  102  followed by a movement of the elevator car  104 . Each of the plurality of predefined building/landing door movement patterns represents opening and closing movement of the door  102 . The plurality of predefined elevator car door movement patterns comprises a predefined movement pattern for each sub-level type elevator car door as discussed above. The plurality of predefined building/landing door movement patterns comprises a predefined movement pattern for each sub-level type building/landing door as discussed above. 
     At a step of  530  of the first determination step  410  the door sensor unit  100  may rate the generated movement patterns of the plurality of door type specific models based on the comparison. The rating of the generated movement patterns of the plurality of door type specific models may e.g. comprise rating the generated movement patterns of the plurality of door type specific models based on that how they match with, i.e. correspond to, the predefined movement patterns. The generated movement patterns of the door type specific models of different sub-types of the elevator car door may be considered to match substantially well with the predefined elevator car door movement patterns, Whereas the generated movement patterns of the door type specific models of different sub-types of the elevator car door may be considered to match substantially poorly with the predefined building/landing door movement patterns. Similarly, the generated movement patterns of the door type specific models of different sub-types of the building/landing door may be considered to match substantially well with the predefined building/landing door movement patterns. Whereas the generated movement patterns of the door type specific models of different sub-types of the building/landing door may be considered to match substantially poorly with the predefined elevator car door movement patterns. 
     The better a generated movement pattern matches with a predefined movement pattern, the higher rating said generated movement pattern may obtain, i.e. receive, as discussed above. In other words, the generated movement patterns of the door type specific models of the different sub-types of the elevator car door may obtain higher ratings when they are compared to the predefined elevator car door movement patterns than when they are compared to the predefined building/landing door movement patterns. Similarly, the generated movement patterns of the door type specific models of the different sub-types of the building/landing door may obtain higher ratings when they are compared to the predefined building/landing door movement patterns than when they are compared to the predefined elevator car door movement patterns. 
     At a step of  540  of the first determination step  410  the door sensor unit  100  may select a group of door type specific models based on the ratings of the generated movement patterns of the plurality of door type specific models as discussed above. The selected group determines the high-level type of the door  102 . If the selected group comprises door type specific models of the different sub-types of the elevator car door, the high-level type of the door  102  may be determined to be the elevator door. Alternatively, if the selected group comprises door type specific models of the different sub-types of the building/landing door, the high-level type of the door may be determined to be the building/landing door. 
     The first determination phase  410  may further comprise a determination of a direction the gravity. Alternatively, the second determination phase  420  may comprise the determination of the direction of the gravity. The determination of the direction of the gravity may comprise observing a long-term average of the obtained movement data, e.g. the acceleration of the door  102 , or an instantaneous value of the obtained movement data, i.e. the acceleration of the door  102 , when the door  102  is determined to be still, i.e. when the accelerometer noise level is low. 
       FIG. 6  schematically illustrates the second determination phase  420  of the determination step  320  in more detailed manner. At a step of  610  of the second determination step  420  the door sensor unit  100  detects one or more directions of the movement representing movement of the door  102  in each movement pattern of the selected group of the door type specific models as described above. The detecting the one or more directions of the movement at the step  610  may comprise filtering the gravity out from the generated movement patterns of the selected group of the door type specific models. In addition, if the selected group comprises door type specific models of the different sub-types of the elevator car door, the detecting the one or more directions of the movement at the step  610  may comprise filtering the movement of the elevator car  104  out from the generated movement patterns of the selected group of the door type specific models. In other words, after filtering the gravity and the movement of the elevator car  104  out from the generated movement patterns of the selected group of the door type specific models, the remaining filtered movement patterns represents the opening and closing movement of the door  102  in the one or more directions depending on the door type specific model. 
     At a step of  620  of the second determination step  420  the door sensor unit  100  selects a winning, i.e. an actual, door type specific model by comparing the filtered movement patterns of the selected group of the door type specific models to predefined movement patterns representing opening and closing movement of sub-level door types. The door type specific model whose filtered movement pattern corresponds to the predefined movement pattern representing opening and closing movement of one of the sub-level door type may be selected as the winning door type specific model, i.e. the door type specific model that corresponds to the sub-level type of the door  102  to which the door sensor unit  100  is arranged, as described above. 
     in addition, according to an example in case that the selected group comprises door type specific models of the different sub-types of the elevator car door, the movement of the elevator car  104  may further be utilized in the selection of the winning door type specific model at the step of  620 , e.g. to define that the elevator car door  102  is closed, if the elevator car  104  is moving, and/or that the movement following the movement of the elevator car  104  is opening of the elevator car door  102 . 
     At a step of  630  of the second determination step  420  the door sensor unit  100  determines the type of the door  102 , i.e. sub-level type of the door  102 , based on the detected one or more directions of the movement of the winning door type specific model. In response to detection of only vertical direction movement, the type of the door  102 , i.e. the sub-level type of the door  102 , may be determined to be a vertically moving door, Alternatively, in response to detection of only horizontal direction movement, the type of the door  102 , i.e. the sub-level type of the door  102 , may be determined to be a horizontally moving door. Alternatively, in response to detection of movement having direction normal to a vertical plane, the type of the door  102 , i.e. the sub-level type of the door  102 , may be determined to be a swing door. Alternatively, in response to detection of horizontal direction movement and movement having direction normal to a vertical plane, the type of the door  102 , i.e. the sub-level type of the door  102 , may be determined to be a folding door. 
     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.