Method and triggering system for triggering acquisition of image data of empty elevator car

Abstract

The invention relates to a method for triggering the acquisition of image data of an empty elevator car (110). The method includes obtaining (310) door status data representative of a status of a door of the elevator car (110), obtaining (320) occupancy status data representative of an occupancy status of the elevator car (110), detecting (330) that the door of the elevator car (110) is closed based on the obtained door status data, detecting (340) that the elevator car (110) is empty based on the obtained occupancy status data, and determining (330) that the elevator car (110) is empty. And in response to detecting that the door of the elevator car (110) is closed and the elevator car (110) is empty, generating (350) a control signal to an imaging device (230) arranged inside the elevator car (110). The control signal comprises instructions for triggering acquisition of the image data of the empty elevator car (110). The invention also relates to a triggering system (200) for triggering the acquisition of image data of an air elevator car (110), and to an elevator system comprising a triggering system (200).

Description

Technical Field

[0001] The present invention generally relates to the technical field of elevators. In particular, the present invention relates to obtaining elevator-related data of an elevator car. Background Art

[0002] In an image analysis based detection solution for an elevator system, a baseline image of an empty elevator car may often be required. For example, the filling level of an elevator car may be defined by comparing the image difference between an image of the interior of the elevator car (when the elevator car is assumed to be full of passengers and / or load) and the baseline image. The accuracy of the image analysis based detection solution may depend on the baseline image. For example, if the floor of the elevator car is changed, e.g. due to new carpet, new floor material, carpet wear, floor material wear or floor color fading, etc., the accuracy of the image analysis based detection solution may decrease and thus the detection results will be affected. Therefore, it is required that the baseline image be kept up to date. Summary of the invention

[0003] A simplified overview is presented below to provide a basic understanding of some aspects of various inventive embodiments. This overview is not a broad overview of the present invention. It is neither intended to identify key or important elements of the present invention nor to describe the scope of the present invention. The following overview only presents some concepts of the present invention in a simplified form as a preface to a more detailed description of exemplary embodiments of the present invention.

[0004] The object of the present invention is to propose a method, a triggering system and an elevator system for triggering the acquisition of image data of an empty elevator car. Another object of the present invention is to provide a method, a triggering system and an elevator system for triggering the acquisition of image data of an empty elevator car so that an appropriate time for triggering the acquisition of image data of an empty elevator car can be defined.

[0005] The objects of the invention are achieved by a method, a triggering system and an elevator system as defined by the respective independent claims.

[0006] According to a first aspect, a method for triggering acquisition of image data of an empty elevator car is provided, wherein the method comprises: obtaining door status data representing a status of a door of an elevator car, obtaining occupancy status data representing an occupancy status of the elevator car, detecting that a door of the elevator car is closed based on the obtained door status data, detecting that the elevator car is empty based on the obtained occupancy status data, and generating a control signal to an imaging device arranged inside the elevator car in response to detecting that the door of the elevator car is closed and the elevator car is empty, wherein the control signal comprises an instruction to trigger acquisition of image data of the empty elevator car.

[0007] The door state data may be obtained from a first sensor device, which is an acceleration sensor device arranged to the elevator car, and wherein the door state data may comprise an acceleration of the elevator car or a deceleration of the elevator car.

[0008] Detecting that the door of an elevator car is closed may include: detecting an acceleration phase of elevator travel of the elevator car based on the acceleration of the elevator car, wherein detecting the acceleration phase of the elevator car indicates that the door of the elevator car is closed; or detecting a deceleration phase of elevator travel of the elevator car based on the deceleration of the elevator car, wherein detecting the deceleration phase of the elevator car indicates that the door of the elevator car is closed.

[0009] Alternatively, detecting closing of the door of the elevator car may comprise detecting a constant speed phase of elevator travel of the elevator car based on an acceleration of the elevator car or a deceleration of the elevator car, wherein detecting the constant speed phase of the elevator car indicates closing of the door of the elevator car.

[0010] The occupancy status data may be obtained from a second sensor device, which is a time-of-flight (ToF) sensor device arranged inside the elevator car, and wherein the occupancy status data may include distance data.

[0011] Detecting that the elevator car is empty may include detecting whether any object is present inside the elevator car based on the distance data, wherein detecting the absence of an object inside the elevator car indicates that the elevator car is empty.

[0012] Alternatively or additionally, the method may further include receiving acquired image data of an empty elevator car, and updating a baseline image of an image analysis based detection algorithm based on the received image data.

[0013] According to a second aspect, a triggering system for triggering acquisition of image data of an empty elevator car is provided, wherein the triggering system comprises: a first sensor device configured to provide door state data representing the state of a door of the elevator car, a second sensor device configured to provide occupancy state data representing the occupancy state of the elevator car, an imaging device arranged inside the elevator car and configured to acquire image data of the interior of the elevator car, and a control unit configured to: obtain the door state data from the first sensor device, obtain the occupancy state data from the second sensor device, detect that the door of the elevator car is closed based on the obtained door state data, detect that the elevator car is empty based on the obtained occupancy state data, and generate a control signal to the imaging device in response to detecting that the door of the elevator car is closed and the elevator car is empty. Wherein, the control signal comprises an instruction for triggering acquisition of image data of the empty elevator car.

[0014] The first sensor device may be an acceleration sensor device arranged to the elevator car, and wherein the door state data may comprise an acceleration of the elevator car or a deceleration of the elevator car.

[0015] Detecting the closing of an elevator car door may include configuring the control unit to: detect an acceleration phase of elevator travel of the elevator car based on an acceleration of the elevator car, wherein detection of the acceleration phase of the elevator car indicates that the door of the elevator car is closed; or detect a deceleration phase of elevator travel of the elevator car based on a deceleration of the elevator car, wherein detection of the deceleration phase of the elevator car indicates that the door of the elevator car is closed.

[0016] Alternatively, detecting closing of the door of the elevator car may include configuring the control unit to detect a constant speed phase of elevator travel of the elevator car based on an acceleration of the elevator car or a deceleration of the elevator car, wherein detecting the constant speed phase of the elevator car indicates closing of the door of the elevator car.

[0017] The second sensor device may be a time-of-flight (ToF) sensor device arranged inside the elevator car, and wherein the occupancy status data may include distance data.

[0018] Detecting that the elevator car is empty may include configuring the control unit to detect whether there is any object inside the elevator car based on the distance data, wherein detecting the absence of the object inside the elevator car indicates that the elevator car is empty.

[0019] Alternatively or additionally, the control unit may be further configured to receive acquired image data of an empty elevator car from an imaging device, and update a baseline image of the image analysis-based detection algorithm based on the received image data.

[0020] According to a third aspect, an elevator system is provided, wherein the elevator system comprises at least one elevator car configured to travel along a respective elevator shaft, and a triggering system as described above.

[0021] Various exemplary and non-limiting embodiments of the invention, both as to constructions and methods of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific exemplary and non-limiting embodiments when read in connection with the accompanying drawings.

[0022] The verbs "comprise" and "include" are used in this document as open limitations, which neither exclude nor require the existence of unrecited features. Unless explicitly stated otherwise, the features recited in the dependent claims are mutually freely combinable. Furthermore, it should be understood that the use of "a" or "an" (i.e. the singular) throughout this document does not exclude a plurality. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Embodiments of the invention are illustrated by way of example and not limitation in the figures of the accompanying drawings.

[0024] Figure 1 An example of an elevator system is schematically shown.

[0025] Figure 2A An example of a triggering system for triggering the acquisition of image data of an empty elevator car is schematically shown.

[0026] Figure 2B An example implementation of a triggering system for triggering the acquisition of image data of an empty elevator car in an elevator system is schematically illustrated.

[0027] Figure 3 An example of a method for triggering the acquisition of image data of an empty elevator car is schematically shown.

[0028] Figure 4 An example of components of a control unit of a triggering system is schematically shown. DETAILED DESCRIPTION

[0029] Figure 1 Schematically illustrated is an example of an elevator system 100. The elevator system 100 includes at least one elevator car 110 configured to travel along a corresponding elevator shaft 120 between a plurality of landings. Figure 1 The example elevator system 100 includes one elevator car 110 traveling along one elevator shaft 120, however the elevator system 100 may also include an elevator group, i.e., a group of two or more elevator cars 110, each of which travels along a separate elevator shaft 120, and the elevator shafts 120 are configured to operate as a unit serving the same landing (for clarity, Figure 1 The elevator system 100 also includes an elevator control system, such as an elevator controller 130. The elevator control system 130 may be configured to at least partially control the operation of the elevator system 100. The elevator control system 130 may reside, for example, in a machine room (not shown in the figure for clarity). Figure 1 The elevator system 100 may also include one or more other known elevator-related entities, such as a hoisting system, a user interface device, a safety circuit and device, an elevator door system, etc., which are not shown in the figure for the sake of clarity. Figure 1 The elevator system 100 also includes a trigger system 200 for triggering the acquisition of image data of the empty elevator car 110 (for the sake of clarity, the entity of the trigger system 200 is not shown in FIG. Figure 1 ).

[0030] Figure 2AAn example of a triggering system 200 for triggering acquisition of image data of an empty elevator car 110 is schematically shown. The triggering system 200 comprises a first sensor device 210, a second sensor device 220, an imaging device 230, and a control unit 240. The first sensor device 210, the second sensor device 220, and the imaging device 230 are communicatively coupled to the control unit 240. The communication between the control unit 240 and other entities of the system 200 (i.e., the first sensor device 210, the second sensor device 220, and / or the imaging device 230) may be based on one or more known wired or wireless communication technologies. Figure 2B An example implementation of a triggering system 200 in an elevator system 100 is shown.

[0031] The first sensor device 210 is configured to provide door status data representing the status of a door of the elevator car 110 (for clarity, Figure 2B The first sensor device 210 may be, for example, an acceleration sensor device. The first sensor device 210 as an acceleration sensor device may be arranged on the elevator car 110. For example, the acceleration sensor device 210 may be arranged on the roof of the elevator car 110, such as Figure 2B As shown in the example of . Alternatively, the acceleration sensor device 210 can be arranged at any other location in the elevator car 110 (inside the elevator car 110 or outside the elevator car 110). Alternatively, the first sensor device can be, for example, a door sensor device. The first sensor device 210 as a door sensor device can be, for example, arranged at the door of the elevator car 110. For the sake of clarity, Figure 2B 2 is not shown in the embodiment of the present invention. Alternatively, the first sensor device 210 may be, for example, an elevator data acquisition device having a connection to an elevator control signal of the elevator system 100. The elevator data acquisition device (e.g., a data transmission unit (DTU)) is configured to obtain different elevator-related data including door status data. For the sake of clarity, Figure 2B The elevator data acquisition device implementation of the first sensor device 210 is not shown in FIG. Alternatively, the first sensor device 210 may be any other sensor device capable of providing door status data.

[0032] The second sensor device 220 is configured to provide occupancy status data representing an occupancy status of the elevator car 110. The second sensor device 220 may, for example, be a time-of-flight (ToF) sensor device. The second sensor device 220, which is a ToF sensor device 220, may be arranged inside the elevator car 110. For example, the ToF sensor device 220 may, for example, be arranged to the ceiling 202 of the elevator car 110. Preferably, the ToF sensor device 220 may, for example, be arranged substantially in the middle of the ceiling 202 of the elevator car 110. This allows the occupancy status data provided by the ToF sensor device 220 to be provided from the largest possible area of ​​the elevator car 110. Preferably, the ToF sensor device 220 may be placed so that the occupancy status data provided by the ToF sensor device 220 is provided from at least the entire area of ​​the floor 204 of the elevator car 110. In Figure 2B In the example of FIG. 2 , the ToF sensor device 220 is arranged substantially in the middle of the ceiling 202 of the elevator car 110 , but the ToF sensor device 220 may also be arranged at any other point on the ceiling 202 of the elevator car 110 .

[0033] The imaging device 230 is configured to acquire image data of the interior of the elevator car 110. The imaging device 230 may be disposed inside the elevator car 110. The image data provided by the imaging device 230 may include one or more images and / or a video image including a plurality of consecutive images (i.e., frames). The imaging device 230 may be disposed (e.g., placed) at different locations within the elevator car 110. Some non-limiting example placements of the imaging device 230 may include: middle placement (e.g., the imaging device 230 may be placed in a middle placement), corner placement (e.g., the imaging device 230 may be placed in a corner placement), and ceiling placement (e.g., the imaging device 230 may be placed in a ceiling placement). For example, the middle placement may be located horizontally in the middle of the rear wall of the elevator car 110, such as Figure 2B Alternatively, the middle placement may be located horizontally in the middle of any other wall of the elevator car 110. For example, the corner placement may be at the upper rear corner of the elevator car 110. The upper rear corner of the elevator car 110 may be any of the upper rear corners of the elevator car 110. Alternatively, the corner placement may be at the upper front corner of the elevator car 110. The upper front corner of the elevator car 110 may be any of the upper front corners of the elevator car 110. Figure 2BAs shown in the example of , the imaging device 230 may preferably be placed near the ceiling 202 of the elevator car 110, i.e. as high as possible. The imaging device 230 may be placed so that the image data provided by the imaging device 230 covers the largest possible area of ​​the elevator car 110. Preferably, the imaging device 230 may be placed so that the image data provided by the imaging device 230 completely covers at least the floor 204 of the elevator car 110. The imaging device 230 may, for example, include a camera, such as a red-green-blue (RGB) camera or a black-and-white camera. The imaging device 230 may be capable of providing image data with a high resolution and / or a wide field of view (FOV) to cover the largest possible area of ​​the elevator car 110 with the image data.

[0034] The control unit 240 may be configured to at least partially control one or more operations of the trigger system 200. The control unit 240 may be arranged to the elevator car 110 (e.g., on the roof of the elevator car 110 or any other location in the elevator car 110, inside the elevator car 110, or outside the elevator car 110), any on-site location in the elevator system 100, or any off-site location remote from the elevator system 100 (e.g., the control unit 240 may be implemented as a remote control unit, a cloud-based control unit, or any other off-site control unit). The control unit 240 may be communicatively coupled to the elevator control system 130 of the elevator system 100. The communication between the control unit 240 and the elevator control system 130 may be based on one or more known communication technologies, wired or wireless.

[0035] Next, by referring to Figure 3 An example of a method for triggering acquisition of image data of an empty elevator car 110 will be described. Figure 3 The method is schematically shown in a flow chart.

[0036] At step 310, the control unit 240 obtains door state data representing the state of the door of the elevator car 110. The state of the door of the elevator car 110 may be, for example, closed, open, closing, or opening. The control unit 240 may obtain the door state data from the first sensor device 210. As described above, the first sensor device 210 may be an acceleration sensor device. The door state data obtained from the acceleration sensor device 210 may include the acceleration of the elevator car 110 or the deceleration of the elevator car 110. Alternatively, as described above, the first sensor device 210 may be a door sensor device or an elevator data acquisition device. The door state data obtained from the door sensor device or the elevator data acquisition device may include the state of the door. Obtaining the door state data using another sensor device different from the imaging device 230 itself makes it unnecessary for the FOV of the imaging device 230 to cover the door of the elevator car 110. This enables a narrower FOV to be achieved, which in turn enables the use of a cheaper imaging device 230.

[0037] At step 320, the control unit 240 obtains occupancy state data representing an occupancy state of the elevator car 110. The occupancy state of the elevator car 110 may be, for example, empty or occupied. The state of the elevator car 110 may be empty, for example, if there are no objects, such as human objects (e.g., passengers or maintenance personnel, etc.) or non-human objects (e.g., loads or animals, etc.) inside the elevator car 110. For example, if there are one or more objects (human or non-human objects) inside the elevator car 110, the state of the elevator car may be occupied. The control unit 240 may obtain the occupancy state data from the second sensor device 220. As described above, the second sensor device 220 may be a ToF sensor device arranged inside the elevator car 110. The occupancy state data obtained from the ToF sensor device 220 may include distance data. The ToF sensor device 220 includes a light source (e.g., an infrared (IR) light source) and an image sensor. The ToF sensor device 220 is configured to illuminate a scene, such as the interior of the elevator car 110, using the light source, and obtain light reflected from the scene using the image sensor. The ToF sensor device 220 may define the distance (from the ToF sensor device 220) to each point in the scene based on the reflected light. The distance data may include the distance to each point in the scene. Alternatively or additionally, the distance data may include three-dimensional (3D) depth data formed based on the distance to each point in the scene. The 3D depth data may, for example, include a depth map or point cloud data of the scene (i.e., the interior of the elevator car 110). For example, if there are one or more objects inside the elevator car 110, at least a portion of the light emitted from the light source of the ToF sensor device 220 is reflected from the one or more objects, so that one or more objects inside the elevator car 110 can be detected based on the distance data. Next, some advantages of using the ToF sensor device 220 to generate occupancy status data of the elevator car 110 are discussed. The ToF sensor device 220 is substantially fast and can therefore provide occupancy status data in real time. The data demonstrated by the ToF sensor device 220 is non-intrusive data, which enables improved privacy protection. The ToF sensor device 220 does not require ambient lighting for optimal performance, which in turn enables the ToF sensor device 220 to be used also in low light or even in complete darkness. The ToF sensor device 220 is a low-cost sensor device having a substantially simple structure. Figure 3 In the example, step 310 of obtaining door status data is performed before step 320 of obtaining occupancy status data, but the method is not limited thereto, and the occupancy status data may be obtained before obtaining the door status data or the occupancy status data and the door status data may be obtained substantially simultaneously.

[0038] At step 330, the control unit 240 detects that the door of the elevator car 110 is closed based on the obtained door state data. In the case where the obtained door state data includes the state of the door of the elevator car 110 (e.g., if the door state data is obtained from the first sensor device 210 as a door sensor device or an elevator data acquisition device), the control unit 240 may detect whether the door of the elevator car 110 is closed based on the state of the door of the elevator car 110 included in the door state data. In the case where the obtained door state data includes the acceleration of the elevator car 110 (e.g., if the door state data is obtained from the first sensor device 210 as an acceleration sensor device), detecting that the door of the elevator car 110 is closed may, for example, include detecting an acceleration phase of elevator travel of the elevator car 110 based on the acceleration of the elevator car 110. For example, the control unit 240 may detect when the acceleration of the elevator car 110 meets a predefined constant acceleration threshold value to detect the acceleration phase of elevator travel of the elevator car 110. During the acceleration phase of the elevator travel of the elevator car 110, the door of the elevator car 110 is most likely to be closed. Therefore, the detection of the acceleration phase of the elevator car 110 indicates that the door of the elevator car 110 is closed. The predefined constant acceleration threshold value may, for example, be a known threshold value or be defined before the implementation of the triggering system 200. Alternatively, in the case where the obtained door state data includes the deceleration of the elevator car 110 (for example, if the door state data is obtained from the first sensor device 210 as an acceleration sensor device), detecting the closing of the door of the elevator car 110 may, for example, include detecting the deceleration phase of the elevator travel of the elevator car 110 based on the deceleration of the elevator car 110. For example, the control unit 240 may detect when the deceleration of the elevator car 110 meets the predefined constant deceleration threshold value to detect the deceleration phase of the elevator travel of the elevator car 110. Similarly, as during the acceleration phase of the elevator travel of the elevator car 110, during the deceleration phase of the elevator travel of the elevator car 110, the door of the elevator car 110 is most likely to be closed. Thus, detecting a deceleration phase of the elevator car 110 indicates that the door of the elevator car 110 is closed. The predetermined constant deceleration threshold may, for example, be a known threshold or be defined prior to the implementation of the triggering system 200. The verb "satisfy" in the context of a threshold (e.g., a predefined constant acceleration threshold and / or a predefined constant deceleration threshold) is used in this patent application to indicate that a predefined condition is satisfied. For example, the predefined condition may be reaching and / or exceeding a predefined threshold.Alternatively, in the case where the obtained door state data includes the acceleration of the elevator car 110 and / or the deceleration of the elevator car 110 (e.g., if the door state data is obtained from the first sensor device 210 as an acceleration sensor device), detecting that the door of the elevator car 110 is closed may include detecting a constant speed phase of elevator travel of the elevator car 110 based on the acceleration of the elevator car 110 or the deceleration of the elevator car 110. For example, the control unit 240 may detect the constant speed phase of elevator travel of the elevator car 110 by integrating the acceleration or deceleration of the elevator car 110 to separate the constant speed phase of elevator travel of the elevator car 110 from the static phase of elevator travel of the elevator car 110. During the constant speed phase of elevator travel of the elevator 110, the door of the elevator car 110 is most likely to be closed. Therefore, the detection of the constant speed phase of the elevator car 110 indicates that the door of the elevator car 110 is closed. Detecting the door status (i.e., the door of the elevator car 110 is closed) based on the movement of the elevator car 110 (e.g., the acceleration of the elevator car 110 and / or the deceleration of the elevator car 110) is simpler than detecting the door status based on, for example, analyzing image data obtained by the imaging device 230 from the elevator car 110. This is particularly beneficial in third-party elevator systems, where door designs can vary.

[0039] At step 340, the control unit 240 detects that the elevator car 110 is empty based on the obtained occupancy status data. Detecting that the elevator car 110 is empty may, for example, include detecting whether there are any objects inside the elevator car 110 based on the distance data. Detecting that there are no objects inside the elevator 110 indicates that the elevator car 110 is empty. For example, detecting that the elevator car 110 is empty based on the obtained distance data may include comparing the obtained distance data with reference distance data representing a reference distance value of an empty elevator car 110. If the obtained distance data is at least partially different from the reference distance data, it may indicate that one or more objects are present inside the elevator car 110. For example, if the distances at at least some points of the scene included in the obtained distance data are different from the reference distance values ​​at corresponding points of the scene. Alternatively, if the obtained distance data substantially corresponds to the reference distance data, it may indicate that there are no objects inside the elevator car 110.

[0040] exist Figure 3In the example of , step 330 of detecting that the door of the elevator car 110 is closed is performed after step 320 of obtaining the occupancy status data and before step 340 of detecting that the elevator car 110 is empty, but the method is not limited thereto, and step 330 of detecting that the door of the elevator car 110 is closed may be performed at any time after obtaining the door status data at step 310 (e.g., immediately after obtaining the door status data or delayed after obtaining the door status data), and step 340 of detecting that the elevator car 110 is empty may be performed at any time after obtaining the occupancy status data at step 320 (e.g., immediately after obtaining the occupancy status data or delayed after obtaining the occupancy status data). Step 330 of detecting that the door of the elevator car 110 is closed may also be performed substantially simultaneously with step 340 of detecting that the elevator car 110 is empty.

[0041] At step 350, in response to detecting at step 330 that the door of the elevator car 110 is closed and at step 340 that the elevator car 110 is empty, the control unit 240 generates a control signal to the imaging device 230. The control signal includes instructions to trigger the acquisition of image data of the empty elevator car 110. Because the control unit 240 has defined at step 340 that the elevator car 110 is empty and defined at step 330 that the door of the elevator car 110 is closed, resulting in no object being able to enter the elevator car 110, the control unit 240 can conclude that it is an appropriate time for the imaging device 230 to provide image data of the empty elevator car 110. The use of the trigger system 200 and the method discussed above improves the reliability that image data can be provided from the empty elevator car 110. In other words, the trigger system 200 and the method discussed above improve the definition that the elevator car 110 is empty so as to trigger the acquisition of image data of the empty elevator car 110.

[0042] In response to receiving the control signal from the control unit 240, the imaging device 230 may trigger the acquisition of image data of the empty elevator car 110. The imaging device 230 may further provide the acquired image data of the empty elevator car 110 to the control unit 240. At step 360, the control unit 240 may receive the acquired image data of the empty elevator car 110 from the imaging device 230. At step 370, the control unit 240 may further update the baseline image of the detection algorithm based on the image analysis based on the received image data. If the received image data includes one image of the empty elevator car 110, the control unit 240 may replace the previous baseline image with the one image included in the received image data. Alternatively, if the received image data includes more than one image of the empty elevator car 110, the control unit 240 may calculate the average of the images to form an average image of the empty elevator car 110. The control unit 240 may further replace the previous baseline image with the formed average image of the empty elevator car 110. Thereby, the accuracy of the updated baseline image is improved. The detection algorithm based on image analysis may be, for example, an elevator car filling level detection algorithm, which may be used to define the filling level of the elevator car 110. The detection algorithm based on image analysis may be based on using a baseline image of an empty elevator car 110. For example, in the elevator car filling level detection algorithm, the filling level of the elevator car 110 may be defined by comparing the image difference between at least one image of the interior of the elevator car 110 captured with the imaging device 230 when the elevator car 110 is assumed to be full of passengers and / or load and the baseline image. Therefore, it is important to keep the baseline image refreshed (i.e., updated) frequently. The use of the trigger system 200 and the method for triggering the acquisition of image data of an empty elevator car 110 enables the inference of the appropriate time for the imaging device 230 to acquire image data of an empty elevator car 110 (i.e., when the elevator car 110 is empty and the door of the elevator car 110 is closed, so that no object can enter the elevator car 110) for updating the baseline image. This improves the accuracy of the baseline image, and therefore also improves the accuracy of the detection algorithm based on image analysis.

[0043] Figure 4An example of components of the control unit 240 is schematically shown. The control unit 240 may include a processing unit 410 having one or more processors, a memory unit 420 having one or more memories, a communication unit 430 having one or more communication devices, and a possible user interface (UI) unit 440. The mentioned elements may be communicatively coupled to each other via, for example, an internal bus. The memory unit 420 may store and maintain parts of a computer program (code) 425, obtained door state data, obtained occupancy state data, obtained image data, baseline images, and any other data. The computer program 425 may include instructions that, when executed by the processing unit 410 of the control unit 240, may cause the processing unit 410 and thus the control unit 240 to perform desired tasks, such as one or more of the above-mentioned method steps. Thus, the processing unit 410 may be arranged to access the memory unit 420 and retrieve any information from the memory unit 420 and store any information to the memory unit 420. For clarity, a processor herein refers to any unit suitable for processing information and controlling the operation of the control unit 240 and other tasks. Operations may also be implemented with a microcontroller solution with embedded software. Similarly, the memory unit 420 is not limited to a certain type of memory, but any memory type suitable for storing the described multiple pieces of information may be applied in the context of the present invention. The communication unit 430 provides one or more communication interfaces for communicating with any other unit (e.g., the first sensor device 210, the second sensor device 220, the imaging device 230, the elevator control system 130, one or more databases) or with any other unit. The user interface unit 440 may include one or more input / output (I / O) devices such as buttons, keyboards, touch screens, microphones, speakers, displays, etc. for receiving user input and output information. The computer program 425 may be a computer program product that may be included in a tangible non-volatile (non-transitory) computer-readable medium that carries the computer program code 425 embodied therein for use with a computer (i.e., the control unit 240).

[0044] The specific examples provided in the description given above should not be construed as limiting the applicability and / or interpretation of the appended claims.The lists and groups of examples provided in the description given above are not exhaustive unless expressly stated otherwise.

Claims

1. A method for triggering acquisition of image data of an empty elevator car (110), the method comprising: obtaining (310) door status data representing the status of a door of the elevator car (110), obtaining (320) occupancy status data representing an occupancy status of the elevator car (110), detecting (330) closing of a door of the elevator car (110) based on the obtained door status data, detecting (340) that the elevator car (110) is empty based on the obtained occupancy status data, and In response to detecting that the door of the elevator car (110) is closed and the elevator car (110) is empty, a control signal is generated (350) to an imaging device (230) arranged inside the elevator car (110), wherein the control signal includes an instruction to trigger acquisition of image data of the empty elevator car (110).

2. The method according to claim 1, wherein the door state data is obtained from a first sensor device (210), the first sensor device being an acceleration sensor device arranged to the elevator car (110), and wherein the door state data comprises an acceleration of the elevator car (110) or a deceleration of the elevator car (110).

3. The method of claim 2, wherein detecting the closing of the door of the elevator car (110) comprises: detecting an acceleration phase of elevator travel of the elevator car (110) based on the acceleration of the elevator car (110), wherein the detection of the acceleration phase of the elevator car (110) indicates that a door of the elevator car (110) is closed; or A deceleration phase of elevator travel of the elevator car (110) is detected based on a deceleration of the elevator car (110), wherein detection of the deceleration phase of the elevator car (110) indicates that a door of the elevator car (110) is closed.

4. The method of claim 2, wherein detecting closing of the door of the elevator car (110) comprises detecting a constant speed phase of elevator travel of the elevator car (110) based on an acceleration of the elevator car (110) or a deceleration of the elevator car (110), wherein detecting the constant speed phase of the elevator car (110) indicates closing of the door of the elevator car (110).

5. The method according to any of the preceding claims, wherein the occupancy status data are obtained from a second sensor device (220), the second sensor device being a time-of-flight (ToF) sensor device arranged inside the elevator car (110), and wherein the occupancy status data comprise distance data.

6. The method of claim 5, wherein detecting that the elevator car (110) is empty comprises detecting whether any object is present within the elevator car (110) based on the distance data, wherein detecting the absence of an object within the elevator car (110) indicates that the elevator car (110) is empty.

7. The method according to any one of the preceding claims, further comprising: receiving (360) acquired image data of an empty elevator car (110), and A baseline image of the image analysis based detection algorithm is updated ( 370 ) based on the received image data.

8. A triggering system (200) for triggering acquisition of image data of an empty elevator car (110), the triggering system (200) comprising: a first sensor device (210) configured to provide door state data indicative of a state of a door of the elevator car (110), a second sensor device (220) configured to provide occupancy status data indicative of an occupancy status of the elevator car (110), an imaging device (230) arranged inside the elevator car (110) and configured to acquire image data of the interior of the elevator car (110), and The control unit (240) is configured as follows: obtaining the door status data from the first sensor device (210), obtaining the occupancy status data from the second sensor device (220), detecting closing of a door of the elevator car (110) based on the obtained door status data, detecting that the elevator car (110) is empty based on the obtained occupancy status data, and In response to detecting that the door of the elevator car (110) is closed and the elevator car (110) is empty, a control signal is generated to the imaging device (230), wherein the control signal includes instructions to trigger acquisition of image data of the empty elevator car (110).

9. The trigger system (200) according to claim 8, wherein: The first sensor device (210) is an acceleration sensor device arranged to the elevator car (110), and wherein the door state data comprises an acceleration of the elevator car (110) or a deceleration of the elevator car (110).

10. The trigger system (200) according to claim 9, wherein: Detecting the closing of the door of the elevator car (110) includes configuring the control unit (240) to: detecting an acceleration phase of elevator travel of the elevator car (110) based on the acceleration of the elevator car (110), wherein the detection of the acceleration phase of the elevator car (110) indicates that a door of the elevator car (110) is closed; or A deceleration phase of elevator travel of the elevator car (110) is detected based on a deceleration of the elevator car (110), wherein detection of the deceleration phase of the elevator car (110) indicates that a door of the elevator car (110) is closed.

11. The trigger system (200) according to claim 9, wherein: Detecting the closing of the door of the elevator car (110) includes configuring the control unit (240) to: detect a constant speed phase of elevator travel of the elevator car (110) based on the acceleration of the elevator car (110) or the deceleration of the elevator car (100), wherein detection of the constant speed phase of the elevator car (110) indicates that the door of the elevator car (110) is closed.

12. The triggering system (200) according to any one of claims 8 to 11, wherein the second sensor device (220) is a time-of-flight (ToF) sensor device arranged inside the elevator car (110), and wherein the occupancy status data comprises distance data.

13. The trigger system (200) according to claim 12, wherein: Detecting that the elevator car (110) is empty includes configuring the control unit (240) to detect whether there is any object in the elevator car (110) based on the distance data, wherein detecting that there is no object in the elevator car (110) indicates that the elevator car (110) is empty.

14. The trigger system (220) according to any one of claims 8 to 13, wherein: The control unit (240) is further configured to: receiving acquired image data of an empty elevator car (110) from the imaging device (230), and A baseline image of an image analysis based detection algorithm is updated based on the received image data.

15. An elevator system (100), comprising: at least one elevator car (110) configured to travel along a corresponding elevator shaft (120), and The trigger system (200) according to any one of claims 8 to 14.

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