Monitoring objects in an elevator shaft using a UAV

Abstract

The invention relates to a method and a system for monitoring a movable object in an elevator shaft by means of an unmanned aerial vehicle (UAV). The UAV is positioned in a desired position within the elevator shaft, wherein the movable object to be monitored is within the field of view of the image sensor of the UAV, and the movement of the UAV is automatically synchronized with the movement of the movable object based on the position and movement characteristics of the UAV and received status data. The image sensor of the UAV obtains image data of the movable object during the elevator operation, and the image data is stored and / or wirelessly transmitted.

Description

Technical Field

[0001] This invention relates to a method, system, and computer program product that involves following an object within an enclosed space using a drone (UAV). More specifically, this invention relates to using UAVs to monitor movable objects in an elevator shaft. Background Technology

[0002] Predictive maintenance of elevators requires a large amount of data for monitoring their condition. Mechanical or electronic problems often manifest as increased temperature or noise before eventual failure. Therefore, continuous measurement of temperature or noise is beneficial for predictive maintenance. However, even when increased temperature or noise is detected, the root cause of the noise is not always clear.

[0003] For troubleshooting purposes, it may be necessary to monitor one or more parts of the elevator during operation. However, the monitored part may be located in a place, such as the bottom or top of the elevator car, that is not visible to a single person while the elevator is being moved.

[0004] In a typical elevator system, there is a machine room located away from the elevator. This machine room contains one or more controllers used to control the elevator's operation. These controllers can adjust elevator parameters and provide error codes in case of operational errors. Therefore, to perform maintenance work, it is often necessary to enter the machine room to input information into and / or receive information from the elevator's control system.

[0005] "Unmanned aerial vehicle" is a general term for various types of unmanned aerial vehicles (UAVs).

[0006] So-called "follow me" drones (UAVs) capable of tracking moving objects are available on the market. This tracking capability has been achieved using GPS devices maintained by the object to be followed, through visual recognition technology or a combination thereof.

[0007] Patent applications US2020072624 and US2020072613 disclose methods for flying unmanned aerial vehicles (UAVs) in internal passageways such as elevator shafts. The elevator shaft may include sensors that report the elevator's position, and the data may also include the elevator's speed, direction of travel, and any other attributes used to determine or predict the elevator's expected position during the UAV's path. This functionality is solely for the purpose of avoiding collisions between the UAV and the elevator, thereby enabling the UAV to use the elevator shaft as an internal passageway to its destination.

[0008] Patent application JP2019142245 discloses an unmanned aerial vehicle (UAV) for performing inspections inside elevator shafts. The UAV is attached to a steel cable via sliding contacts for guidance to mitigate collisions, specifically those caused by wind.

[0009] As is known in the art, a digital twin refers to a virtual copy of a physical object. A digital twin is formed based on digital data representing the physical object, generated and / or collected. A digital twin is provided by at least one processing device and at least one associated memory. Summary of the Invention

[0010] The aim is to provide a method and apparatus for addressing the problem of inspecting objects within an elevator shaft during elevator operation.

[0011] According to a first aspect, a method for monitoring a movable object in an elevator shaft using a unmanned aerial vehicle (UAV) is provided. The method includes positioning the UAV at a desired location within the elevator shaft, wherein the movable object to be monitored is within the field of view of the UAV's image sensor; determining the position and movement characteristics of the UAV based on information obtained by at least one sensor carried by the UAV; wirelessly receiving status data regarding a movable elevator car within the elevator shaft; automatically synchronizing the movement of the UAV with the movement of the movable object based on the determined position and movement characteristics of the UAV itself and the received status data; simultaneously acquiring image data of the movable object via the UAV's image sensor during elevator operation; and storing and / or wirelessly transmitting the acquired image data displaying the movable object.

[0012] According to the second aspect, positioning the UAV to the desired location includes a) receiving an indication of a movable object as a reference to a corresponding object in the digital twin of the elevator, and automatically moving the UAV to the desired location using the digital twin of the elevator and the position and movement characteristics of the UAV, or b) guiding the UAV to the desired location using a manual remote control, and receiving an indication of the movable object to be monitored from the user by referring to an image of the movable object shown in an image provided by the UAV's image sensor.

[0013] According to the third aspect, the status data includes at least one of elevator floor call information, destination information, and sensor information related to the movement and / or position of the elevator car within the elevator shaft.

[0014] According to the fourth aspect, the status data includes first status data and / or second status data. The method includes receiving first status data using wireless communication, the first status data including elevator floor call information and / or destination information from the elevator controller; and / or receiving second status data using wireless communication. The second status data is generated based on sensor information obtained from one or more sensors of a sensor unit attached to the elevator car, wherein the second status data includes at least one of the position, acceleration, and velocity of the elevator car and / or the sensor unit.

[0015] According to the fifth aspect, based on the determined position and movement characteristics of the UAV itself and the received state data, a digital twin of the elevator is used to perform the synchronization of the movement of the UAV with the movement of the movable object.

[0016] According to a first system aspect, a system for monitoring a movable object in an elevator shaft is provided. The system includes a UAV (Unmanned Aerial Vehicle), the UAV including an image sensor and at least one sensor configured to provide information on the position and movement characteristics of the UAV; and a display unit configured to display images acquired by the image sensor of the UAV. The UAV is configured to be positioned at a desired location within the elevator shaft, wherein the movable object to be monitored is within the field of view of the image sensor of the UAV, to determine its position and movement characteristics based on information acquired by at least one sensor included in the UAV, to receive state data regarding a movable elevator car within the elevator shaft, to automatically synchronize the movement of the UAV with the movement of the movable object based on the determined position and movement characteristics of the UAV itself and the received state data, and to simultaneously acquire image data of the movable object via the image sensor during elevator operation, and to store and / or wirelessly transmit the acquired image data showing the movable object for display on a display device.

[0017] According to the second system aspect, the UAV includes a) a digital twin of the elevator, and a communication device for receiving an indication of a movable object as a reference to a corresponding object in the digital twin of the elevator, wherein the UAV is configured to automatically move to a desired location using at least the digital twin of the elevator and the position and movement characteristics of the UAV, or b) the communication device, configured to receive instructions provided by a manual remote control unit for guiding the UAV to the desired location, and to receive an indication of a movable object to be monitored from a user by referring to an image of the movable object displayed in an image obtained by the UAV's image sensor and displayed by a display device.

[0018] According to the third system aspect, the status data includes at least one of elevator floor call information, destination information, and sensor information related to the movement and / or position of the elevator car within the elevator shaft.

[0019] According to the fourth system aspect, the status data includes first status data and / or second status data. The UAV includes at least one wireless communication unit configured to receive first status data from the elevator controller regarding elevator floor call information and / or destination information, and / or receive second status data, wherein the second status data, generated based on sensor information obtained from one or more sensors of a sensor unit attached to the elevator car, includes at least one of the position, acceleration, and velocity of the elevator car and / or the sensor unit.

[0020] According to the fifth system aspect, the UAV includes a digital twin of the elevator, and the UAV is configured to use the digital twin of the elevator to synchronize the movement of the UAV with the movement of the movable object, based on the determined position and movement characteristics of the UAV itself and the received state data of the elevator car.

[0021] This invention is based on the concept of using information about the position and movement of a UAV and the position and movement of an elevator car, wherein a digital twin of the elevator is used to synchronize the movement of the UAV with the movement of a monitored object associated with the elevator car.

[0022] The advantage of this invention is that it can capture at least one photograph or video representing a moving object (i.e., a part of the elevator to be monitored) during elevator operation.

[0023] Because UAVs can maintain their position relative to the monitored object for extended periods, technicians can operate the UAV from the machine room and directly monitor the monitored object within the elevator shaft. Therefore, technicians no longer need to move back and forth between the machine room and the elevator shaft, or have another technician monitor various objects in the shaft while a technician in the machine room monitors things like error codes or status information from the controller. This can be particularly advantageous when, for example, controller parameters are being adjusted and the elevator is being used to test the effect of those adjustments. Furthermore, while the UAV can automatically synchronize itself with the movement of the monitored object, the operator only needs to direct the object to the UAV, and no manual control of the UAV is required during its synchronized operation—this is known as synchronous mode. In this way, the UAV can provide real-time feedback to technicians, improving the efficiency of maintenance work and reducing maintenance downtime when the elevator is unavailable to ordinary users. Faster elevator inspections and a reduction in the number of maintenance personnel required result in shorter elevator downtime and lower maintenance costs. Attached Figure Description

[0024] The present invention will now be described in more detail with reference to the accompanying drawings and preferred embodiments, wherein...

[0025] Figure 1This is a schematic diagram of the main components of an elevator.

[0026] Figure 2 Some components of the UAV and sensor unit, which are convenient for operation according to the present invention, are schematically shown.

[0027] Figure 3 The steps of the first method are shown.

[0028] Figure 4 The steps of the second method are shown. Detailed Implementation

[0029] Figure 1 A schematic diagram of an elevator equipped with a system according to the invention is shown. The elevator car (10), which may be simply referred to as the car (10), operates in an elevator shaft (11). The car (10) is moved by a hoist and carried by ropes (14) attached to the car (10). One or more counterweights (12) are typically attached to the ropes (14) and guided by counterweight guides (not shown), and the one or more counterweights (12) move in the opposite direction to the car (10). In conventional elevators, there is a machine room above the elevator shaft, while many modern elevators have a hoist 13 inside the elevator shaft (11). The elevator shaft (11) and / or the car (10) also include a large number of various operating and safety mechanisms. According to the invention, a UAV (20) operates within the elevator shaft (11), and within the elevator shaft (11), the UAV operates at least partially automatically: the UAV can be assigned tasks and then performed by the UAV without the need for continuous operator control of its movement. A docking station (30) can be provided for the UAV (20), preferably attached to the outside of the car (10). Preferably, the docking station (30) is located on the top plate of the car (10) so that the UAV (20) can descend from above onto the docking station (30). However, for the purpose of performing the supervision operation according to the invention, the docking station (30) is not required, as the UAV (20) can also be temporarily inserted into the elevator shaft (11) above or below the elevator car (10) only during the corresponding inspection. The elevator controller 16 controls the operation of the elevator. The elevator controller 16 is typically located near the elevator shaft (11) and can serve a single elevator or a group of elevators; in the case of a group of elevators, it is typically referred to as the elevator group controller.

[0030] Figure 2 Some components of the UAV and sensor unit, which are convenient for operation according to the present invention, are schematically shown.

[0031] The UAV (20) includes at least one processing device (200) operable for performing automatic navigation of the UAV and collecting sensor information and communications. The at least one processing device (200) includes avionics, i.e., electronic systems for managing various systems of the UAV, controlling communications, navigation, display, and other functions. The UAV (20) is provided with a plurality of sensors (201a to 201n) operably coupled to the at least one processing device (200). The plurality of sensors includes at least one image sensor (201a) (such as a camera), and preferably includes at least one of a remote thermometer, accelerometer, gyroscope, magnetometer, lidar, radar, pressure sensor, and humidity sensor and / or any other suitable sensor.

[0032] At least one processing device (200) is operatively coupled to at least one memory (205) for storing computer program code including computer-executable instructions for the at least one processing device (200), and for at least temporarily storing information received from the sensors (201a, 201b, 201c, 201d…201n) of the UAV (20) and / or via communication units (210, 220). The at least one processing device (200) is further operatively coupled to a first communication unit (210) for providing communication between the UAV (20) and a sensor unit (30) attached to the elevator car. The sensor unit (30) is provided or operatively connected to a wireless communication unit for enabling communication between the UAV and the sensor unit (30). The sensor unit (30) is preferably disposed on the top panel of the elevator car. The sensor unit (30) may also operate as a docking station for the UAV, for example, capable of charging the UAV's battery. The first communication unit (210) can be a so-called short-range wireless communication unit, for example, operating according to any suitable short-range communication technology standard, including but not limited to wireless local area network (WLAN), Bluetooth, Bluetooth Low Energy (BLE), and mesh technologies such as Thread and Bluetooth Mesh. Short-range wireless communication enables the docking station not only to dock and communicate with the UAV (20), but also to dock and communicate with other components, such as internal sensors of the elevator in the elevator shaft.

[0033] The UAV (20) may include a second communication unit (220) for providing a second wireless communication via an external communication network (70), which may be, for example, a cellular network, such as a 3G, 4G, or 5G cellular network, or any other suitable long-range communication network. The external communication network (70) is operable to preferably provide bidirectional communication between the UAV (20) and one or more control and / or supervisory entities (80), such as towards elevator controllers, elevator group controllers, computing equipment, maintenance equipment, monitoring equipment, operation control centers, etc. Alternatively, the second communication unit (220) may be a short-range wireless communication device, such as a WLAN device, which provides communication to the external communication network via a gateway device (not shown).

[0034] A first communication unit (210), a second communication unit (220), or a third communication unit (225) operably connected to at least one processing device (200) is operable to provide communication between the UAV (20) and a remote control unit (90) operable by a technician for enabling manual remote control of the UAV. Figure 2 One option is shown, in which there is a dedicated third communication unit (225) that provides a wireless connection for remote control of the remote control unit (90). This wireless connection may be dedicated solely to remote control, or it may be a two-way wireless connection that enables, for example, the wireless transmission of image data obtained by the image sensor of the UAV (20) to the remote control unit (90) which is equipped with or connected to a display.

[0035] The UAV (20) also includes a charging unit (230) for charging at least one battery (235) of the UAV, which provides power to the aforementioned functional elements of the UAV (20), as well as other suitable devices for operating its thrusters (not shown) or for providing thrust that enables the UAV to be maneuvered in the air under the control of avionics.

[0036] The sensor unit (30) includes a communication unit (310) for communicating information with a first communication unit (210) of the UAV (20). The communication unit (310) is operatively coupled to at least one processing device (300). The sensor unit (30) is provided with a plurality of sensors (301a, 301b, 301c…301n) operatively coupled to at least one processing device (300). The plurality of sensors include at least one of a thermometer, an accelerometer, a gyroscope, a magnetometer, and a pressure sensor. One of the primary purposes of the sensors included in the sensor unit (30) is to provide real-time information on the movement and / or position of the elevator car. When the sensor unit (30) is attached to the elevator car, the position and / or movement information of the sensor unit (30) can be used to determine the position and / or movement of the elevator car. At least one processing device (300) is operatively coupled to at least one memory 305 for storing computer program code including computer-executable instructions for the at least one processing device (300), and for at least temporarily storing information received from a plurality of sensors 301a to 301n. A communication unit (310) provides wireless communication between a corresponding second communication unit (210) of the UAV (20) and the sensor unit (30). The second communication unit (210) providing communication to the first communication unit (210) of the UAV (20) is a short-range wireless communication device operating according to the same communication standard as the first communication unit (210).

[0037] As is known in the art, a typical UAV (20) operates with electrical power. The sensor unit (30) can be implemented as a docking station, in which case the sensor unit typically includes a charging station (330) for charging and recharging at least one battery (235) of the UAV (20) 331. However, for the purposes of this invention, the charging station (330) is not required and is therefore optional, and is thus marked with a dashed outline.

[0038] Figure 3 A first embodiment of the method and system according to the present invention is illustrated schematically.

[0039] In the first embodiment, a technician uses a remote control (90) to guide the UAV (20) closer to an object (301) that the technician wants to monitor by manually controlling the UAV. The remote control (90) may be a conventional UAV remote control device with or without a display, or the remote control may be operatively associated with a control and supervision entity (80). During this step, the UAV's image sensor preferably continuously acquires image data (302), which is wirelessly communicated (303) and displayed (304) by a display device that may be associated with the control and supervision entity (80) and / or the remote control (90), allowing the technician to visually determine where the UAV (20) is moving to facilitate the guidance process.

[0040] At least one image sensor of the UAV preferably acquires real-time video images during a manual remote control step.

[0041] When the UAV reaches the desired location, the object to be monitored is displayed in an image acquired by the image sensor of the UAV (20), and a technician can point out the object to be monitored in the acquired image displayed on a monitor (304). The object to be monitored is determined using computer vision and the pointing, and this information is sent to the UAV (305), thereby causing the UAV to enter a synchronization mode (307) (306), in which the UAV automatically begins to follow the selected object within the elevator shaft independently of the movement state of the object being followed. Any known computer-based method for pointing out objects in an image can be used, such as pointing out an object in a touchable user interface via a mouse, finger, or stylus, or pointing out an object by a user using a virtual reality (VR) user interface, which can be implemented, for example, using a VR headset. The computer vision application is preferably used to identify and lock the pointed-out object to be monitored, and information about the pointed-out object to be monitored is communicated back to the UAV.

[0042] During synchronization mode (307), the UAV uses its wireless communication capabilities to continuously receive (308, 309) status data from the sensor unit (30) and / or from the control and supervision entity (80). During synchronization mode, the UAV also continuously uses (310) its own sensors to determine its own position within the elevator shaft. One or more processing devices (200) of the UAV utilize the received status data and information about the UAV's own position to control avionics to automatically synchronize the UAV's movement with the movement of the monitored object.

[0043] During synchronous mode (307), the UAV stores and / or wirelessly transmits (311) image data acquired using its image sensors. Preferably, the image data includes streaming real-time video images. The processing delay of the image data does not render the image data non-real-time. During synchronous mode (307), the monitored object is continuously displayed (312) on a display associated with the control and supervision unit (80) and / or remote controller (90), allowing a technician to visually inspect the operation of the monitored object based on the displayed images, thereby enabling the technician to determine whether the monitored object is operating correctly. In enhanced embodiments, machine vision and learning can be used to analyze the images acquired during synchronous mode and determine whether the monitored object is operating correctly. As an alternative to or supplement to real-time video image streaming, the UAV can store the acquired image data, such that the image data can be later transmitted for monitoring at the control and supervision unit (80) and / or for machine vision-based analysis of previously acquired and stored image data. For example, storing image data may be a preferred alternative if the communication capabilities provided within the elevator shaft are not sufficiently good for continuous streaming of real-time video.

[0044] Synchronization mode (307) enables the UAV to follow any object that moves with the elevator car.

[0045] Figure 4 An alternative embodiment is shown that utilizes a digital twin to locate the object to be monitored. A technician, using a control and supervision entity (80), directs (401) the object to be monitored by the UAV with the aid of the elevator's digital twin. Information is sent (402) to the UAV, which receives this information and automatically moves (403) via applicable communication; in other words, without further manual navigation control, using the digital twin and the UAV's own positional information, the directed object to be monitored is positioned within the UAV's image sensor's field of view.

[0046] The same digital twin or two substantially similar digital twins should be usable for both the control and supervision entity (80) and the UAV (20). The digital twin contained in the UAV is stored in the UAV's memory (205) and used by at least one processing device (200) of the UAV. Similarly, the digital twin contained in the control and supervision entity (80) is stored in the control system's memory and executed by at least one processing device of the control and supervision entity (80).

[0047] A digital twin of an elevator includes at least information about the physical dimensions and / or structure of the elevator shaft and elevator car. The digital twin may further include information about various mechanical components of the elevator, including but not limited to hoisting equipment, travel ropes, guide rails, counterweight, and safety mechanisms. Preferably, the digital twin also includes information about the position and movement characteristics of the elevator car, such as the elevator car's landing position, speed, and / or acceleration characteristics during operation. The digital twin preferably includes information that enables the UAV to calculate the position and movement characteristics of the counterweight, which is related to the position and movement characteristics of the elevator car and can therefore be calculated using a simple mathematical model based on the position and movement information of the car and / or sensor units.

[0048] When the UAV (20) automatically moves (403) to the desired position, the UAV may optionally acquire image data and wirelessly transmit (404) the image data to a control and monitoring entity (80). The control and monitoring entity may display (405) the acquired image data to a technician to verify that the UAV has moved to the correct position within the elevator shaft. Optionally, the technician may use a remote control (not shown) of the control and monitoring entity (80) to fine-tune the position of the UAV relative to the object to be monitored, for example, to fine-tune the desired field of view of the acquired image. Optionally, when it is determined that the position of the UAV (20) is correct and the desired object is correctly displayed in the acquired image, a confirmation (406) is sent to the UAV (20).

[0049] When the UAV (20) is in the desired position, it enters the synchronization mode (307).

[0050] To monitor an object moving synchronously with the elevator car, the UAV is set to synchronization mode (307). In synchronization mode, the UAV automatically synchronizes its movement with the movement of the monitored object, and therefore also with the movement of the elevator car, using sensors and status data. In this case, automation means that the UAV controls its own position relative to the object being followed without needing to receive intervention or control from the operator.

[0051] In order for a UAV to move automatically within an elevator shaft, the UAV uses its own sensors to measure its surrounding environment. These sensors may include at least one of lidar, radar, and image sensors, and the UAV determines its own position and speed relative to the elevator car and elevator shaft based on the obtained sensor information.

[0052] The UAV also receives elevator status data. The UAV can wirelessly receive first status data from the elevator controller via any of its wireless communication interfaces. For example, the first status data can be received via a standardized application programming interface (API) provided to the elevator controller, which can be obtained via an external communication network (70). The first status data may include, for example, elevator floor call information and destination information. Second status data can be wirelessly received from a sensor unit (30) attached to the elevator car. The sensor unit may be a UAV docking station equipped with sensors, communication capabilities, and a charging unit for charging the UAV, or the sensor unit may be a general-purpose sensor unit with or operatively coupled to a wireless communication unit for wirelessly transmitting status data to the UAV. The second status data received by the UAV from the sensor unit (30) may include, for example, the current speed and / or acceleration of the elevator car. The second status data received by the UAV may include raw sensor data, or the raw sensor data may be preprocessed by the sensor unit to produce status data in any suitable format before the status data is wirelessly transmitted to the UAV. The status data provided by the sensor unit improves the accuracy and speed of determining the motion characteristics of the elevator car and / or the monitored object. The improved accuracy of motion characteristics enhances the synchronization of the UAV's movement with the elevator car and / or the movement of the monitored object moving with the elevator car. This, in turn, improves the stability of the images of the monitored object provided by the UAV's image sensors.

[0053] The monitored object is preferably directly or indirectly connected to the elevator car and thus moves with the elevator car. The UAV avionics includes a synchronization module that operates to match the speed and acceleration of the UAV with the speed and acceleration of the elevator car, thereby synchronizing the movement of the UAV with the movement of the monitored object. Furthermore, the UAV avionics maintains the UAV's orientation relative to the elevator shaft, ensuring that the inspected object remains within the field of view of the corresponding image sensor.

[0054] To improve positioning accuracy, the UAV preferably uses a digital twin of the elevator to predict the elevator car's acceleration and velocity profile. Using a digital twin facilitates motion synchronization, making the UAV independent of traditional proportional-integral-derivative (PID) control algorithms or other similar algorithms, which can lead to increased synchronization delays. By using a digital twin, the UAV can automatically adjust its own acceleration and velocity based on the expected acceleration and velocity of the elevator car. Information obtained from the UAV's sensors and / or image sensors can be further used to fine-tune the synchronization of the UAV's movement with the movement of the monitored object.

[0055] It will be apparent to those skilled in the art that the basic idea of ​​this invention can be implemented in various ways as technology advances. Therefore, this invention and its embodiments are not limited to the examples described above, but can be varied within the scope of the claims.

Claims

1. A method for monitoring movable objects in an elevator shaft using a drone (UAV), the method comprising: - Position the UAV to a desired location within the elevator shaft, wherein the movable object to be monitored is within the field of view of the UAV's image sensor; - The position and movement characteristics of the UAV are determined based on information obtained by at least one sensor carried by the UAV; - Wirelessly receive status data about the elevator car that can move within the elevator shaft; - By automatically synchronizing the movement of the UAV with the movement of the movable object based on the determined position and movement characteristics of the UAV and the received state data, the speed and acceleration of the UAV are matched with the speed and acceleration of the elevator car moving within the elevator shaft. Simultaneously, image data of the movable object is acquired by the UAV's image sensor during elevator operation. - Store and / or wirelessly transmit the obtained image data displaying the movable object.

2. The method according to claim 1, wherein positioning the drone to the desired location includes: a) Receive the instruction from the movable object as a reference to the corresponding object in the digital twin of the elevator, and automatically move the UAV to the desired location using the digital twin of the elevator and the position and movement characteristics of the UAV, or b) Guide the UAV to the desired location using a manual remote control and receive instructions from the user regarding the movable object to be monitored by referring to an image of the movable object displayed in an image provided by the UAV's image sensor.

3. The method according to claim 1 or 2, wherein the status data includes at least one of elevator floor call information, destination information, and sensor information related to the movement and / or position of the elevator car within the elevator shaft.

4. The method according to claim 3, wherein the state data includes first state data and / or second state data, wherein the method includes: - The first status data is received using wireless communication, and the first status data includes elevator floor call information and / or destination information from the elevator controller; and / or - The second state data is received using wireless communication, wherein the second state data is generated based on sensor information obtained by one or more sensors of a sensor unit attached to the elevator car, wherein the second state data includes at least one of the position, acceleration, and velocity of the elevator car and / or the sensor unit.

5. The method of claim 1, wherein the synchronization of the movement of the UAV with the movement of the movable object is performed using a digital twin of the elevator based on the determined position and movement characteristics of the UAV itself and the received state data.

6. A system for monitoring movable objects in an elevator shaft, the system comprising: An unmanned aerial vehicle (UAV) includes an image sensor and at least one sensor configured to provide information on the position and movement characteristics of the UAV. and The display unit is configured to display images obtained by the image sensor of the UAV; The UAV is characterized in that it is configured as follows: - Positioned in the desired location within the elevator shaft, wherein the movable object to be monitored is within the field of view of the UAV's image sensor; - Determine the position and movement characteristics of the UAV based on information obtained by at least one sensor contained in the UAV; - Receive status data about the elevator car that can move within the elevator shaft; - By automatically synchronizing the movement of the UAV with the movement of the movable object based on the determined position and movement characteristics of the UAV itself and the received state data, the speed and acceleration of the UAV are matched with the speed and acceleration of the elevator car moving within the elevator shaft. Furthermore, during elevator operation, image data of the movable object is simultaneously acquired via the image sensor. - Store and / or wirelessly transmit the acquired image data displaying the movable object for displaying the acquired image data on a display device.

7. The system of claim 6, wherein the UAV comprises: a) A digital twin of the elevator, and a communication device, the communication device being configured to receive an indication of the movable object as a reference to a corresponding object in the digital twin of the elevator, wherein the UAV is configured to automatically move to a desired location using at least the digital twin of the elevator and the position and movement characteristics of the UAV, or b) A communication device configured to receive instructions provided by a manual remote control unit for guiding the UAV to a desired location, and to receive instructions from a user for a movable object to be monitored by referring to an image of the movable object displayed in an image obtained by the image sensor of the UAV and displayed by the display device.

8. The system according to claim 6 or 7, wherein the status data includes at least one of elevator floor call information, destination information, and sensor information related to the movement and / or position of the elevator car within the elevator shaft.

9. The system of claim 8, wherein the status data includes first status data and / or second status data, and wherein the UAV includes at least one wireless communication unit, the wireless communication unit being configured to: - Receive the first status data from the elevator controller, the first status data relating to the elevator's floor call information and / or destination information; and / or - Receive the second state data, wherein the second state data is generated based on sensor information obtained by one or more sensors of a sensor unit attached to the elevator car, and the second state data includes at least one of the position, acceleration, and velocity of the elevator car and / or the sensor unit.

10. The system of claim 6, wherein the UAV includes a digital twin of the elevator, and the UAV is configured to use the digital twin of the elevator to synchronize the movement of the UAV with the movement of the movable object based on determined position and movement characteristics of the UAV itself and received elevator car status data.

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