Patent Publication Number: US-2023150797-A1

Title: Elevator door control

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation of PCT International Application No. PCT/FI2020/050498 which has an International filing date of Jul. 21, 2020, the entire contents of which are incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The example and non-limiting embodiments of the present invention relate to controlling and/or monitoring operation of a door of an elevator. 
     BACKGROUND 
     Correct operation of elevator doors is an important aspect in terms of safety and convenience of elevator passengers. In particular, timely opening the doors to enable passengers to enter and exit an elevator car plays an important role in avoiding undue delays in passenger transport, while keeping the doors open only when the elevator car is in a position that ensures safe entry thereto and exit therefrom is critical in terms of passenger safety. 
     In many elevator systems the elevator doors are automatically operated such that opening and closing the elevator doors is carried out via using a driving system that comprises an electric motor arranged to drive movement of the elevator doors under control of an elevator door controller. Since elevator cars and elevator doors are manufactured in a multitude of different sizes in accordance with the requirements of their specific usage environments, the driving system and/or the elevator door controller need to be configured for each elevator car separately in order to ensure reliable, efficient and safe operation. However, configuration of the elevator door controller typically requires manual work and/or usage of hardware dedicated to the configuration procedure, which may introduce additional cost in manufacturing and installing the elevator system while also making the configuration procedure prone to errors. 
     SUMMARY 
     It is an object of the present invention to provide a technique that facilitates configuring and/or monitoring operation of an elevator car door in a flexible but yet reliable and cost-effective manner. 
     According to an example embodiment, an apparatus for controlling at least one aspect of operation of an elevator car door via operating a door driving system arranged to drive movement of the car door between first and second end positions of its movement range, wherein the door driving system comprises an electric motor that is coupled to the car door via a transmission system and wherein, the elevator car comprises a door coupler connected to the car door for temporarily coupling the car door to a landing door when the elevator car resides in a landing zone of a landing such that the landing door moves between a closed position and an open position together with the car door is provided, the apparatus configured to: control movement of the car door, monitor one or more parameters that are descriptive of power consumption of said electric motor upon movement of the car door, and carry out a configuration procedure comprising: recording a first power consumption profile that is descriptive of the power consumption of said electric motor as a function of the car door position when the car door is moved from the first end position to the second end position, recording a second power consumption profile that is descriptive of the power consumption of said electric motor as a function of the car door position when the car door is moved from the second end position to the first end position, and designating one of the first and second end positions as a closed door position and the other one of the first and second end positions as an open door position based on one or more characteristics of the first and second power consumption profiles. 
     According to another example embodiment, an elevator car is provided, the elevator car comprising: a car door arranged in the elevator car; a door driving system for driving movement of the car door between a first and second end positions of its movement range, wherein the door driving system comprises an electric motor that is coupled to the car door via a transmission system; a door coupler connected to the car door for temporarily coupling the car door to a landing door when the elevator car resides in a landing zone of a landing such that the landing door moves between a closed position and an open position together with the car door; and a door controller according to the example embodiment described in the foregoing. 
     According to another example embodiment, a method for controlling at least one aspect of operation of an elevator car door arranged in an elevator car via operating a door driving system arranged to drive movement of the car door between first and second end positions of its movement range, wherein the door driving system comprises an electric motor that is coupled to the car door via a transmission system and wherein, the elevator car comprises a door coupler connected to the car door for temporarily coupling the car door to a landing door when the elevator car resides in a landing zone of a landing such that the landing door moves between a closed position and an open position together with the car door is provided, the method comprising: monitoring one or more parameters that are descriptive of power consumption of said electric motor upon movement of the car door; recording a first power consumption profile that is descriptive of the power consumption of said electric motor as a function of the car door position when the car door is moved from the first end position to the second end position; recording a second power consumption profile that is descriptive of the power consumption of said electric motor as a function of the car door position when the car door is moved from the second end position to the first end position, and designating one of the first and second end positions as a closed door position and the other one of the first and second end positions as an open door position based on one or more characteristics of the first and second power consumption profiles. 
     According to another example embodiment, a computer program for controlling at least one aspect of operation of an elevator car door is provided, the computer program comprising computer readable program code configured to cause performing at least the method according to the example embodiment described in the foregoing when said program code is executed on one or more computing apparatuses. 
     The computer program according to the above-described example embodiment may be embodied on a volatile or a non-volatile computer-readable record medium, for example as a computer program product comprising at least one computer readable non-transitory medium having the program code stored thereon, which, when executed by one or more computing apparatuses, causes the computing apparatuses at least to perform the method according to the example embodiment described in the foregoing. 
     The exemplifying embodiments of the invention presented in this patent application are not to be interpreted to pose limitations to the applicability of the appended claims. The verb “to comprise” and its derivatives are used in this patent application as an open limitation that does not exclude the existence of also unrecited features. The features described hereinafter are mutually freely combinable unless explicitly stated otherwise. 
     Some features of the invention are set forth in the appended claims. Aspects of the invention, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of some example embodiments when read in connection with the accompanying drawings. 
    
    
     
       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, where 
         FIG.  1    schematically illustrates some aspects of an elevator system according to an example; 
         FIG.  2    illustrates a block diagram of some logical elements of an elevator control system according to an example; 
         FIG.  3 A  schematically illustrates a reference power consumption profile according to an example; 
         FIG.  3 B  schematically illustrates a reference power consumption profile according to an example; 
         FIG.  4    illustrates a method according to an example; and 
         FIG.  5    schematically illustrates an apparatus according to an example. 
     
    
    
     DESCRIPTION OF SOME EMBODIMENTS 
       FIG.  1    schematically illustrates some aspects of an elevator system  100  provided with automatic doors according to an example, including an elevator car  110  that may be moved in the vertical direction within an elevator shaft  120 . The elevator car  110  may be provided with a car door  111 , wherein the car door  111  comprises a sliding door that may be moved between a closed position and an open position. The car door  111  may be kept locked while the elevator car  110  is moving, unlocked upon the elevator car  110  entering a landing zone located at and close to a landing  130  and opened upon the elevator car  110  stopping at the landing  130 . In contrast, the elevator car door  111  may be closed before the elevator car  110  leaves the landing  130  and locked upon the elevator car  110  exiting the landing zone. Moreover, the elevator car  110  is provided with a door coupler  112  connected to the car door  111  for temporarily coupling the car door  111  to a landing door  131  of the landing  130  when the elevator car  110  resides within the landing zone of the landing  130  such that landing door moves between a closed position and an open position together with the car door  111 , thereby allowing passengers to move between the landing  130  and the elevator car  110  when the elevator car  110  is at the landing  130  while preventing the passengers from entering the elevator shaft  120  when the elevator car  110  is not at the landing  130 . 
     The door coupler  112  may comprise coupling elements that engage corresponding counter elements in the landing door  131  when the elevator car  110  resides within the landing zone of the landing  130 . In this regard, the coupling elements in the door coupler  112  and the counter elements in the landing door  131  are positioned with respect each other such that, when the elevator car  110  is moving past the landing door  131 , the coupling elements are passed between the coupling elements. When the elevator car  110  is at the landing  130  and the car door  111  is moved in order to open the car door  111 , the door coupler  112  in the elevator car  110  engages the counter elements in the landing door  131  and, consequently, when the car door  111  is moved by a door driving system arranged in the elevator car  110 , the landing door  131  moves together with the car door  111 . 
     As an example, the coupling elements may comprise sheet-metal vanes projecting from the door coupler  112  towards the landing door  131 , where the vanes arranged such that they form a vertical ‘slot’ that has its open end directed towards the landing door  131 , whereas the counter elements may comprise one or more rollers mounted on the landing door  131  in a position projecting from the landing door  131  towards the elevator shaft  120 , the axis of the one or more rollers being substantially perpendicular to the plane of the landing door  131 . The door coupler  112  and/or the car door  111  may be further provided with a locking device that closes or locks the car door  111  in such manner that the car door  111  cannot be opened without special measures when the elevator car  111  is outside the landing zone. In other words, the locking device may enable opening the car door  111  (without special measures) only when the elevator car  110  is within the landing zone and hence the car door  111  is substantially vertically aligned with the landing door  131 . The locking device may comprise a mechanical or electromechanical locking arrangement. 
       FIG.  2    illustrates a block diagram of some logical elements of an elevator control system  200  according to an example. The elevator control system  200  may serve to control various aspect related to movement and operation of the elevator car  110 . In this example, the elevator control system  200  is shown with an elevator controller  210  for controlling at least some aspects of movement of the elevator car  110  in the elevator shaft  120 , a door driving system  230  for driving movement of the car door  111  of the elevator car  110  between a closed position and an open position; and a door controller  220  for operating the door driving system  230  and for monitoring at least one aspect of operation of the door driving system  230 . 
     Along the lines described in the foregoing, the elevator controller  210  may be arranged to control at least some aspects of movement of the elevator car  110  in the elevator shaft  120 . The elevator control in this may involve, for example, controlling the speed of the elevator car  110  via control of one or more electric motors arranged to drive the elevator car  110  and braking system arranged to regulate the speed of the elevator car  110 . In context of the present disclosure, an aspect of interest is the operation of the door controller  220  and, consequently, any aspects related to general operation of the elevator controller  210  in controlling movement of the elevator car  110  may be provided using techniques known in the art. Therefore, any further details pertaining to the operation of the elevator controller  210  and/or movement of the elevator car  110  along the elevator shaft  120  are described herein only to extent they are necessary for describing examples that pertain to operation of the door controller  220 . 
     The elevator controller  210  is typically installed outside the elevator car  110 , for example in suitable location in the elevator shaft  120  or in its close proximity, and it may comprise or may be provided using one or more computing devices comprising respective one or more processors arranged to execute one or more computer programs to provide at least some aspects of operation of the elevator controller  210 . Hence, the elevator controller  210  may be provided as an elevator control apparatus (e.g. using a single computer apparatus) or as an elevator control system (e.g. using one or more computer apparatuses). The elevator controller  210  is communicatively coupled to the door controller  220 , where the communicative coupling between the elevator controller  210  and the door controller  220  may be provided using a wired communication network or communication link, using a wireless communication network or communication link, or using a combination of a wireless communication network or communication link and a wireless communication network or communication link. 
     The elevator controller  210  may be further communicatively coupled to one or more further elevator controllers that arranged for controlling at least some aspect of movement of respective elevator cars in other elevator shafts and/or to an elevator group controller arranged to control at least some aspects related to movement of a plurality of elevator cars in a plurality of elevator shafts. 
     Along the lines described in the foregoing, the door driving system  230  may be arranged to drive movement of the car door  111  between the closed position and the open position. In this regard, the door driving system  230  may operate under control of the door controller  220 , e.g. in accordance with one or more door control signals received from the door controller  220 . The door driving system  230  may comprise an electric motor and a motor controller arranged to control operation of the electric motor that is coupled to the car door  111  via a transmission system such that operation of the electric motor causes linear movement of the elevator car door  111  in a direction that is substantially parallel with an opening in a wall of the elevator shaft  120  at the landing  130 , thereby enabling movement of the car door  111  between the closed and open positions. The transmission system may be arranged to convert the rotary motion provided by the electric motor into the linear movement of the car door  111 . Characteristics of the transmission system may be selected in accordance with requirements of a specific implementation of the elevator car  110 , the car door  111  and/or the door driving system  230 , and the transmission ission system may involve, for example, one or more of the following: a belt drive, a chain drive, a gear train, etc. 
     Along the lines described in the foregoing, the door controller  220  may be arranged to control operation of the door driving system  230 , thereby enabling controlling the movement of the car door  111  between the closed and open positions. The door controller  220  may be further arranged to monitor at least one aspect of operation of the door driving system  230 . The door controller  220  is typically installed in the elevator car  110 , for example in suitable location in the interior of the elevator car  110  (e.g. in a ceiling structure of the elevator car  110 ) or on the exterior of the elevator car  110  (e.g. on the roof of the elevator car  110 ). 
     The door controller  220  may comprise or may be provided using a computing device comprising one or more processors arranged to execute one or more computer programs to provide at least some aspects of operation of the door controller  220 . Hence, the door controller  220  may be provided as a door controller apparatus. Along the lines described in the foregoing, the door controller  220  is communicatively coupled to the elevator controller  210 , whereas the door controller  220  is further communicatively coupled to the door driving system  230 , where the communicative coupling between the door controller  220  and the door driving system  230  may be provided using a wired or wireless communication network and/or communication link. 
     The aspect of the door controller  220  controlling the movement of the car door  111  between the closed and open positions may comprise at least the following operations with respect to moving the elevator car door  111 :
     move the car door  111  in a first direction,   move the car door  111  in a second direction that is opposite of the first direction.   

     Each of these operations may be effected via the door controller  220  issuing a respective control signal to the door driving system  230 . The door controller  220  may further enable, for example, setting and/or adjusting movement speed of the car door  111  via application of a respective control signal. 
     The aspect of the door controller  220  monitoring at least one aspect of operation of the door driving system  230  may comprise monitoring one or more parameters that are descriptive of power consumption of the electric motor of the door driving system  230 . As an example in this regard, the door controller  220  may be able to directly monitor or measure the power consumption of the electric motor of the door driving system  230 , whereas in another example the door controller  220  may be able to monitor one or more parameters that are indirectly descriptive of power consumption of the electric motor of the door driving system  230 . As an example of the latter, the door controller  220  may be arranged to monitor one or more characteristics of the electric current and/or voltage supplied to the electric motor of the door driving system  230 , e.g. the magnitude and/or phase of the electric current supplied to the electric motor. Monitoring of the electric current and/or voltage may comprise obtaining respective indications of characteristics of the electric current and/or voltage supplied to the electric motor from the motor controller or using respective measurement arrangements for obtaining respective indications of characteristics of the electric current and/or voltage supplied to the electric motor. 
     The door controller  220  may further enable monitoring a position of a component of the transmission system of the door driving system  230 , which position is at least indirectly indicative of the (relative) position of the car door  111 . As an example in this regard, in case the transmission system of the door driving system  230  comprises a belt drive assembly, the measure of interest may comprise a position of (a predefined reference point in) a driving belt of the belt drive assembly and/or the traveling distance of the driving belt between the closed and open positions of the car door  111 . 
     The aspect of the door controller  220  may monitoring of at least one aspect of operation of the door driving system  230  may comprise the door controller  220  reading or receiving the one or more parameters that are descriptive of the power consumption of the electric motor of the door driving system  230 , possibly together with the position of the component of the transmission system of the door driving system  230 , according to a predefined schedule, e.g. at predefined time intervals. As an example in this regard, predefined time interval may be chosen from the range from 10 to 100 milliseconds, e.g. 50 milliseconds. 
     Upon manufacturing and installation to the elevator car  110 , the door controller  220  may lack knowledge of the type of the car door  111 , the size (e.g. width) of the car door  111  and/or any position reference pertaining to the car door  111  and, consequently, the door controller  220  may initially lack knowledge required for detecting the current position of the car door  111 . In particular, the door controller  220  may initially lack knowledge regarding which one of the end positions of the movement range of the car door  111  represents the closed position and which one represent the open position. An advantage arising from such a manner of providing the door controller  220  is that the same or similar door controller  220  is applicable for any car door  111  regardless of the design of the car door  111  and its arrangement with respect to the elevator car  110 , while on the other hand such an approach requires configuration of the door controller  220  upon configuring or reconfiguring the elevator car  110  for use in order to enable proper operation of the door controller  220 . 
     In this regard, the elevator door controller  220  may be arranged to carry out a configuration procedure to derive position reference data that may be subsequently applied in controlling the door movement in the course of operation of the elevator system  100 . The position reference obtained via the configuration procedure may comprise an indication which one of the end positions of the movement range of the car door  111  represents the closed position and which one represents the open position. The position reference data may further comprise a first reference position for a component of the transmission system of the elevator door driving system  230  and a second reference position for said component of the transmission system of the elevator door driving system  230 , where one of the first and second reference positions may represent the closed position (e.g. a closed end) of the car door  111  and the other one of the first and second reference positions may represent the open position (e.g. an open end) of the car door  111 . Alternatively or additionally, the position reference data may comprise a reference position for said component of the transmission system of the elevator door driving system  230  and a reference distance, where the reference position may represent one of the closed and open positions of the car door  111  and the reference distance may represent the deviation in the position of said component of the transmission system of the elevator door driving system  230  between the closed and open positions of the car door  111 . 
     Derivation of the position reference data according to technique described in the present disclosure provides a reliable and repeatable manner of configuring, reconfiguring and monitoring the operation of the car door  111  without a need to apply any physical components that are dedicated for the configuration procedure. 
     The power consumption of the electric motor of the door driving system  230  varies with the position of the car door  111  due to changes in load of the electric motor in the course of moving the car door from a first end position to a second end position of its movement range, where one of the first and second end positions represents the closed position of the car door  111  and the other one of the first and second end positions represents the open position of the car door  111 . In particular, the load of the electric motor temporarily increases due an additional load resulting from operation of the door coupler  112  (e.g. due to the coupling elements of the door coupler  112  in the car door  111  engaging the counter elements of the landing door  131 ) while the load of the electric motor increases significantly when the car door  111  is moved to end position of its movement range from which it cannot move any further. In the following, a curve that is descriptive of the power consumption of the electric motor of the door driving system  230  as a function of the car door position while moving the car door  111  from one of the first and second end position to the other one is referred to as a power consumption profile. 
     The configuration procedure may be based on recording respective power consumption profiles while moving the car door  111  between the end positions of its movement in both directions. In particular, the configuration procedure may rely on comparing one or more characteristics of the recorded power consumption profiles to respective characteristics of one or more reference power consumption profiles. The reference power consumption profiles may reflect one or more characteristic of the arrangement between the door driving system  230 , the car door  111 , the landing door  131  and the door coupler  112 . As non-limiting examples in this regard,  FIG.  3 A  schematically depicts a first reference power consumption profile that represents the power consumption of the electric motor as a function of the door position when moving the car door  111  from the closed position to the open position, whereas  FIG.  3 B  schematically depicts a second reference power consumption profile that represents the power consumption of the electric motor as a function of the door position when moving the car door  111  from the open position to the closed position. 
     In the first reference power consumption profile, upon starting the car door  111  movement, the power consumption of the electric motor initially rises to and remains at an intermediate power consumption level P c  due to an additional load resulting from operation of the door coupler  112  (designated as “door coupler range” in the illustration of  FIGS.  3 A and  3 B ). After the door coupler range, the force required for moving the car door  111  decreases and, consequently, the power consumption of the electric motor decreases to and remains at a baseline (or nominal) power consumption level P n  until the car door  111  has been moved to the fully open position, which results in steeply increasing power consumption of the electric motor (e.g. a power consumption peak) due to the car door  111  having reached the end position of its movement range. 
     In the second reference power consumption profile, upon starting the car door  111  movement, the power consumption of the electric motor initially remains at the baseline power consumption level P n  until the car door  111  has been moved to the door coupler range. Upon entering the door coupler range, the load resulting from operation of the door coupler  112  causes the power consumption of the electric motor to rise to and remain at the intermediate power consumption level P c  until the car door  111  has been moved to the fully closed position, which results in steeply increasing power consumption of the electric motor (e.g. a power consumption peak) due to the car door  111  having reached the end position of its movement range. In the second reference power consumption profile, the entry to the “door coupler range” may further result in a minor peak in the power consumption of the electric motor, as shown in the illustration of  FIG.  3 B . 
     A further aspect that may have an effect on the power consumption of the electric motor upon moving the car door  111  may arise from a closing weight that may be coupled to the car door  111  and arranged such that it ensures closing the car door  111  in case loss of electric power (and hence inability of the door driving system  230  driving the movement of the car door  111 ): the closing weight may cause a minor increase in load of the electric motor when opening the door in comparison to closing the door. This may make the baseline power consumption level P n  in a power consumption profile pertaining to movement of the car door  111  from the closed position to the open position slightly higher than that that of a corresponding power consumption profile pertaining to movement of the car door  111  from the open position to the closed position. 
     The configuration procedure may comprise recording a first power consumption profile that is descriptive of the power consumed by the electric motor of the door driving system  230  as a function of the car door position when the car door  111  is moved from the first end position to the second end position and recording a second power consumption profile that is descriptive of the power consumed by the electric motor of the door driving system  230  as a function of the car door position when the car door  111  is moved from the second end position to the first end position. In this regard, configuration procedure may comprise operating the door driving system  230  to move the car door  111  from the first end position to the second end position and to move the car door  111  from the second end position to the first end position while measuring the one or more parameters that are descriptive of the power consumption of the electric motor in order to, respectively, record the first and second power consumption profiles. In this regard, the movement towards the first or the second direction may be continued until the power consumption of the electric motor exceeds a predefined peak power threshold P hi  (see also  FIGS.  3 A and  3 B  in this regard), which may be considered as an indication of the car door  111  having reached the respective end position of its movement range. 
     The configuration procedure may further comprise tracking or monitoring the position of a component of the transmission system of the door driving system  230  that at least indirectly represents the (relative) position of the car door  111  while moving the car door  111  from the first end position to the second end position and/or vice versa. Consequently, the configuration procedure may comprise recording the first reference position as the position of said component of the transmission system when the car door  111  is positioned at the first end position of its movement range and/or recording the second reference position as the position of said component of the transmission system when the car door  111  is positioned at the second end position of its movement range. Alternative or additionally, the configuration procedure may further comprise recording the reference distance between respective positions of said component of the transmission system between the first and second end positions of the movement range of the car door  111 . 
     Along the lines described in the foregoing, in an example, the power consumption of the electric motor may be represented by one or more characteristics of the electric current and/or voltage supplied to the electric motor of the door driving system  230 , e.g. by the magnitude of the electric current supplied to the electric motor. In such an example, the first and second power consumption profiles may comprise respective current profiles that are descriptive of the magnitude of the electric current supplied to the electric motor of the door driving system  230  as a function of the car door position between the first and second end positions of its movement range. Further along the lines described in the foregoing, in an example, the transmission system may comprise a belt drive and the first and second reference positions may comprise respective positions of (a predefined reference point in) the driving belt of the belt drive assembly and/or the reference distance may comprise the traveling distance of the driving belt between the closed and open positions of the car door  111 . 
     As described in the foregoing, the elevator door controller  220  may not have the knowledge regarding which one of the first and second end positions represents the closed position of the car door  111  and which one represents the open position of the car door  111 . In this regard, the configuration procedure may comprise designating one of the first and second end positions as the closed door position and designating the other one of the first and second end positions as the open door position based on the first and second recorded power consumption profiles. 
     The designation may rely on one or more characteristics of the first and second recorded power consumption profiles in view of one or more characteristics of reference power consumption profiles that represent the power consumption of the electric motor as a function of the door position, e.g. the ones according to the examples illustrated in  FIGS.  3 A and  3 B . In this regard, the designation may consider the first and second recorded power consumption profiles in their entirety or it may consider a certain portion in the first and second recorded power consumption profiles. In this regard, the designation may comprise identifying a respective door coupler range in each of the first and second recorded power consumption profiles and carrying out the designation in dependence of one or more characteristics of the respective door coupler ranges identified in the first and second recorded power consumption profiles. In this regard, the door coupler range may be identified as a sub-portion of the power consumption profile that exhibits a continuous period of increased power consumption that meets one or more predefined door coupler range criteria, e.g. one or more of the following:
     the power consumption is at least a first predefined margin above the baseline power consumption level but below the predefined peak power threshold P hi ;   the sub-portion covers at least a predefined traveling distance of the car door  111 .   

     Non-limiting examples of using one or more characteristics of the respective door coupler ranges identified in the first and second recorded power consumption profiles in the designation in consideration of the first and second recorded power consumption profiles in their entirety or at least in a major part include the following:
     The first end position may be designated as the closed end position and the second end position may be designated as the open end position in response to the respective identified door coupler range appearing in the beginning of the first recorded power consumption profile and in at the end of the second recorded power consumption profile.   The second end position may be designated as the closed end position and the first end position may be designated as the open end position in response to the respective identified door coupler range appearing in the beginning of the second recorded power consumption profile and in at the end of the first recorded power consumption profile.   

     In further examples, additionally or alternatively, the designation may consider a certain sub-portion of the first and second recorded power consumption profiles, e.g. the respective door coupler ranges identified in the first and second recorded power consumption profiles. Non-limiting examples in this regard include the following:
     The first end position may be designated as the closed end position and the second end position may be designated as the open end position in response to the door coupler range identified in the second recorded power consumption profile terminating to a power consumption peak and the door coupler range identified in the first recorded power consumption profile not terminating to a power consumption peak.   The second end position may be designated as the closed end position and the first end position may be designated as the open end position in response to the door coupler range identified in the first recorded power consumption profile terminating to a power consumption peak and the door coupler range identified in the second recorded power consumption profile not terminating to a power consumption peak.   

     In this regard, a presence of a power consumption peak may be identified via usage of one or more predefined peak criteria, e.g. one or more of the following:
     the power consumption is at least a second predefined margin above the baseline, where the second predefined margin is larger than the first predefined margin;   the power consumption exceeds the predefined peak power threshold P hi .   

     Hence, the designation of one of the first and second end positions as the closed door position and designation of the other one as the open door position provides the door controller  220  with the knowledge of which one of the first and second end positions of the movement range of the car door  111  represents the closed position and which one represents the open position. This information may be stored in a memory available in or otherwise accessible by the door controller  220  for subsequent use in the course of operation of the elevator system  100 . Moreover, the door controller  220  may further transmit an acknowledgement regarding the designation having been successfully completed to the elevator controller  210 . 
     As described in the foregoing, the configuration procedure may comprise tracking or monitoring the position of a component of the transmission system of the door driving system  230  and recording the first reference position as the position of said component of the transmission system when the car door  111  is at the first end position of its movement range and/or recording the second reference position as the position of said component of the transmission system when the car door  111  is at the second end position of its movement range, possibly together with a reference distance that between said first and second reference positions. 
     With the above-described designation of one of the first and second end positions of the car door  111  as the closed position and the other one as the open position, the door controller  220  may further associate the first and/or second reference positions to the closed position of the car door  111  or to the open position of the car door  111  accordingly: in case the first end position of the car door  111  has been found to represent the closed position of the car door  111  (and, conversely, the second end position has been found to represent the open position of the car door  111 ), the first reference position indicates the position of said component of the transmission system when the car door  111  is closed and the second reference position indicates the position of said component of the transmission system when the car door  111  is open, whereas in case the second end position of the car door  111  has been found to represent the closed position of the car door  111  (and, conversely, the first end position has been found to represent the open position of the car door  111 ), the second reference position indicates the position of said component of the transmission system when the car door  111  is closed and the first reference position indicates the position of said component of the transmission system when the car door  111  is open. 
     Consequently, the door controller  220  may operate the car door  111  in accordance with the first and/or second reference positions, possibly in view of the reference distance between the first and second reference positions, e.g. such that one of the first and second reference positions serves as an indication of the closed position of the car door  111  position while the other one serves as an indication of the open position of the car door  111 . 
     The door controller  220  may be arranged to initiate the configuration procedure in response to a command received from the elevator controller  210 , in response to command from an external (computing) device coupled to the elevator controller  210 , or in response to a command received via a user interface provided in the elevator car  110 . Regardless of manner of initiating the configuration procedure, this function is to be made accessible only by maintenance personnel. 
     Once initiated, the door controller  220  may be arranged to carry out the configuration procedure a predefined number of times in order to ensure correct designation of the first and second end positions of the movement range of the car door  111  as the closed door position and the open door position and, possibly, to ensure correctly setting the first and second reference positions for the component of the transmission system of the door driving system  230 . In particular, successful completion of the configuration procedure may require that the configuration procedure described in the foregoing is carried the predefined number of times with the same outcome with respect to designation of the first and second end positions of the movement range of the car door  111  as the closed door position and the open door position in response to a command received from the elevator controller  210  and, if applicable, with the substantially same outcome with respect the first and second reference positions. 
     In the foregoing, the description refers to the car door  111  in singular. However, the description readily generalizes into controlling operation of at least one car door  111  of the elevator car  110  and, consequently, the technique described in the present disclosure is equally applicable, for example, to a single car door  111  opening to the left, a single car door  111  opening to the right, and to a double doors  111  that comprises respective door leaves opening to the left and to the right. In the latter example, the same electric motor and transmission system of the door driving system  230  may be applied for driving the movement of the both door leaves. In case the elevator car  110  comprises two or more independent car doors that are driven by respective separate door driving systems  230 , e.g. respective car doors  111  in both ends of the elevator car  110 , the door controller  220  may carry out the above-described configuration procedure separately for each of the car doors  111 . 
     Standards related to safety of elevator transport require that the elevator car  110  is not allowed to travel unless the car door  111  is fully closed. As an example, closed status of the car door  111  may be provided via usage of a safety switch arranged in the car door  111  that closes a safety chain when the car door  111  is fully closed and consequently issues a monitoring signal, which may be delivered to the elevator controller  210  as a primary car door closed signal to provide an indication of the car door  111  being duly closed. 
     In some situations, such as maintenance operations carried out to the elevator system  100 , it may be necessary to bypass the safety switch, thereby disconnecting the safety chain. In such situations there may be still a need to move the elevator car  110  up or down, whereas safety regulations nevertheless prohibit the elevator controller  220  moving the elevator car  110  without an indication of the car door  111  being fully closed. For such a situation the elevator controller  210  may allow movement of the elevator car  110  in response to receiving a secondary car door closed signal from the door controller  220 , which is secondary car door closed signal is derived using a mechanism that is substantially independent from that applied in derivation of the primary car door closed signal. As an example in this regard, the door controller  220  may substantially continuously record the power consumption profiles resulting from movement of the car door  111  and consider a power consumption profile that ends with the door coupler range and/or a door coupler range within a power consumption profile that terminates with a power consumption peak as an event that may trigger transmission of the secondary car door closed signal to the elevator controller  210 . As another example, alternatively or additionally, the door controller  220  may consider the component of the transmission system reaching the one of the first and second reference positions that is associated with the closed door position as an event that may trigger transmission of the secondary car door closed signal to the elevator controller  210 . 
     The operations pertaining to operation of the door controller  220  with respect to carrying out the configuration procedure may be described as steps of a method. As an example in this regard,  FIG.  4    depicts a flowchart illustrating a method  300 , which may be implemented by the door controller  220 , by a (computing) device coupled to the door controller  220 , or by another entity of the elevator control system  200 . The method  300  commences from monitoring one or more parameters that are descriptive of the power consumption of the electric motor of the door driving system  230  upon movement of the car door  110 , as indicated in block  302 . The method  300  further comprises recording the first power consumption profile that is descriptive of the power consumption of said electric motor as a function of the car door position when the car door  111  is moved from the first end position to the second end position, as indicated in block  304 , and recording the second power consumption profile that is descriptive of the power consumption of said electric motor as a function of the car door position when the car door  111  is moved from the second end position to the first end position, as indicated in block  306 . The method  300  further comprises designating one of the first and second end positions as the closed door position and the other one of the first and second end positions as the open door position based on one or more characteristics of the first and second power consumption profiles, as indicated in block  308 . The method  300  may further comprise operating the car door  111 , after completion of the configuration procedure, in accordance with said designation, as indicated in block  310 . Respective operations described with references to blocks  302  to  310  pertaining to the method  300  may be implemented, varied and/or complemented in a number of ways, for example as described with references to the door controller  220 , to other elements of the elevator control system  200  and/or to another element of the elevator system  100 . 
     Along the lines described in the foregoing, the door controller  220  may comprise or may be provided using one or more computing devices comprising respective one or more processors arranged to execute one or more computer programs to provide at least some aspects of operation of the door controller  220 . As an example in this regard, the operation of the door controller  220  may be provided by a door controller apparatus or by an apparatus arranged to operate as the door controller  220 .  FIG.  5    schematically illustrates some components of an apparatus  400  that may be employed to implement such an apparatus. 
     The apparatus  400  comprises a processor  410  and a memory  420 . The memory  420  may store data and computer program code  425 . The apparatus  400  may further comprise communication means  430  for wired or wireless communication with other apparatuses and/or user I/O (input/output) components  440  that may be arranged, together with the processor  410  and a portion of the computer program code  425 , to provide the user interface for receiving input from a user and/or providing output to the user. In particular, the user I/O components may include user input means, such as one or more keys or buttons, a keyboard, a touchscreen or a touchpad, etc. The user I/O components may include output means, such as a display or a touchscreen. The components of the apparatus  400  are communicatively coupled to each other via a bus  450  that enables transfer of data and control information between the components. 
     The memory  420  and a portion of the computer program code  425  stored therein may be further arranged, with the processor  410 , to cause the apparatus  400  to perform at least some aspects of operation of the door controller  220  described in the foregoing. The processor  410  is configured to read from and write to the memory  420 . Although the processor  410  is depicted as a respective single component, it may be implemented as respective one or more separate processing components. Similarly, although the memory  420  is depicted as a respective single component, it may be implemented as respective one or more separate components, some or all of which may be integrated/removable and/or may provide permanent / semi-permanent/ dynamic/cached storage. 
     The computer program code  425  may comprise computer-executable instructions that implement at least some aspects of operation of the door controller  220  described in the foregoing when loaded into the processor  410 . As an example, the computer program code  425  may include a computer program consisting of one or more sequences of one or more instructions. The processor  410  is able to load and execute the computer program by reading the one or more sequences of one or more instructions included therein from the memory  420 . The one or more sequences of one or more instructions may be configured to, when executed by the processor  410 , cause the apparatus  400  to perform at least some aspects of operation of the door controller  220  described in the foregoing. Hence, the apparatus  400  may comprise at least one processor  410  and at least one memory  420  including the computer program code  425  for one or more programs, the at least one memory  420  and the computer program code  425  configured to, with the at least one processor  410 , cause the apparatus  400  to perform at least some aspects of operation of the door controller  220  described in the foregoing. 
     The computer program code  425  may be provided e.g. a computer program product comprising at least one computer-readable non-transitory medium having the computer program code  425  stored thereon, which computer program code  425 , when executed by the processor  410  causes the apparatus  400  to perform at least some aspects of operation of the door controller  220  described in the foregoing. 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. 
     Reference(s) to a processor herein should not be understood to encompass only programmable processors, but also dedicated circuits such as field-programmable gate arrays (FPGA), application specific circuits (ASIC), signal processors, etc. Features described in the preceding description may be used in combinations other than the combinations explicitly described.