Method for monitoring an elevator car in an elevator shaft and safety system for monitoring an elevator car in an elevator shaft

Abstract

A method for monitoring an elevator car in an elevator shaft is described. The method includes obtaining position data indicative of a position of the elevator car, obtaining motion data indicative of a motion of the elevator car, and determining an estimated position of the elevator car from a dynamic system model. The dynamic system model describes the motion of the elevator car based on input variables. The input variables include the position data and the motion data. The method further includes determining an offset value indicative of an offset of the motion data, the offset value being generated such that the dynamic system model fits the elevator car position indicated by the position data, determining a sensor reliability parameter based on the offset value, and providing output data including the sensor reliability parameter.

Description

[Technical field]

[0001] The present invention relates to a method and safety system for monitoring an elevator car in an elevator shaft, particularly to reliably determine the elevator car's position, speed, and / or acceleration based on multiple sensor inputs. Aspects of the invention relate to the implementation of estimation algorithms for estimating the elevator car's position, speed, and / or acceleration and for determining sensor reliability parameters. [Background technology]

[0002] Elevator installations are known in the art. An elevator includes an elevator shaft or hoistway and an elevator car movably mounted inside the elevator shaft. Elevators suitable for transporting passengers must generally comply with high safety standards. For safety purposes, parameters of the elevator car traveling in the elevator shaft may be monitored and evaluated by a safety system. Such parameters may include the acceleration, speed, and / or position of the elevator car. If the parameters are outside of a safe range, the safety system may indicate an unsafe condition and the elevator installation may respond, for example, by applying brakes or running the elevator car at a reduced speed. The acceptable range of a parameter may be defined in relation to values ​​of other parameters. For example, an acceptable speed in a direction towards the end of the hoistway may be reduced compared to an acceptable speed in the middle of the hoistway.

[0003] By combining different sensor types, various safety-relevant parameters can be measured and evaluated by the safety system. However, the reliability or accuracy of some sensor types may be limited, which may cause an inaccurate assessment of the elevator installation's condition if each sensor is evaluated independently, which may result in false alarms or even unsafe conditions.

[0004] Furthermore, different sensors used in conventional elevator installations, such as overspeed governors or overtravel protection systems, are typically installed at different locations inside the elevator installation and are therefore difficult to install or maintain. Summary of the Invention

[0005] It would therefore be beneficial to provide an improved system or method for monitoring an elevator car inside an elevator shaft. SUMMARY OF THE DISCLOSURE The present invention at least partially solves the above problems.

[0006] The invention is set out in the accompanying claims.

[0007] According to an aspect, a method of monitoring an elevator car in an elevator shaft is described. The method includes obtaining position data indicative of a position of the elevator car, obtaining motion data indicative of a motion of the elevator car, and determining an estimated position of the elevator car from a dynamic system model. The dynamic system model describes the motion of the elevator car based on input variables. The input variables include the position data and the motion data. The method further includes determining an offset value indicative of an offset of the motion data, the offset value being generated such that the dynamic system model fits the elevator car position indicated by the position data, determining a sensor reliability parameter based on the offset value, and providing output data including the sensor reliability parameter.

[0008] According to an aspect, a safety system for monitoring an elevator car in an elevator shaft is described. The safety system includes a position sensor configured to obtain position data indicative of a position of the elevator car, a motion sensor configured to obtain motion data indicative of a motion of the elevator car, and an evaluation unit. The evaluation unit is configured to receive input variables including the motion data and the position data and to determine an estimated position of the elevator car from a dynamic system model. The dynamic system model describes the motion of the elevator car based on the input variables. The input variables include the position data and the motion data. The evaluation unit is further configured to determine an offset value indicative of an offset of the motion data. The offset value is generated such that the dynamic system model fits the elevator car position indicated by the position data. The evaluation unit is further configured to determine a reliability parameter of the sensor based on the offset value and provide output data including the reliability parameter of the sensor.

[0009] According to an aspect, obtaining position data indicative of an elevator car location is described. The position data may be obtained by a position sensor. The position data may indicate a position of the elevator car inside the elevator shaft, i.e., may include information representative of the position of the elevator car inside the elevator shaft. The position may be an absolute position. In particular, the (absolute) position data may be data obtained by a sensor and may represent a measured position of the elevator car that is within an error margin of the sensor. For example, the position data may include a value indicative of a distance between the elevator car and a reference point, such as a shaft floor, a shaft top, or any point located inside the elevator shaft, at a given time. For example, the position data may indicate or include a representation of the distance in meters between the positions of the lowest landing doors, although this example should not be understood as limiting. Thus, the position sensor may be configured to sense a distance between the elevator car and a reference point inside the elevator shaft.

[0010] The position data may beneficially be determined for any potential location of the elevator car within the elevator shaft, and may not be specifically limited to being determined only at a particular position of the elevator car within the elevator shaft, such as when the elevator car is near a landing door. Thus, the position sensor may be configured to sense the position of the elevator car at essentially any position of the elevator car within the elevator shaft. Additionally or alternatively, the position data may be determined under conditions in which the position sensor can provide accurate readings, such as when the elevator car is traveling at a slow speed, or even when the elevator car is stopped.

[0011] According to an embodiment, the position sensor may be an optical distance sensor, in particular a laser distance sensor. According to an embodiment, the position sensor may be provided on the elevator car, such as on or adjacent to the top or bottom of the exterior of the elevator car, and may have a field of view that includes a reference point inside the elevator shaft, such as the top or bottom of the elevator shaft. According to an embodiment, a reflector, such as a retroreflector, or a reflective or mirror-like surface, may be provided at the reference point, although the reflector may be optional and may be omitted if the reflectivity of the reference point is sufficient for the particular elevator installation. The distance sensor, in particular a laser distance sensor, may be configured to determine the distance between the distance sensor and the reference point by time-of-flight measurements. Additionally or alternatively, distance sensors, in particular optical distance sensors, utilizing triangulation, multiple frequency phase-shift, and / or interferometry may be utilized without departing from the scope of the present disclosure.

[0012] According to alternative embodiments, the locations of the distance sensor and the reference point may be reversed, for example the distance sensor may be provided at a fixed point inside the elevator shaft and the reference point may be provided on the elevator car.

[0013] According to an aspect, obtaining motion data indicative of elevator car motion is described. The motion data may be obtained by a motion sensor. The motion data may be indicative of, for example, the speed or velocity of the elevator car and / or the acceleration of the elevator car. Motion data indicative of an elevator car that is stopped, i.e., has a speed of zero, and an elevator car that has no acceleration, is considered motion data indicative of elevator motion. Motion data indicative of changes in elevator car acceleration over time is considered motion data. Data indicative of measurable parameters unrelated to the linear motion of the elevator car inside the elevator shaft, such as, for example, vibrations of the elevator car that can be measured by an accelerometer, is generally not considered motion data. The motion data may include data representing the relative motion of the elevator car, such as information defining the relative motion with respect to the position of the elevator car. For example, the motion data may include values ​​indicative of the difference between the positions of the elevator car at different times and / or the distance traveled between times. Thus, a series of motion data indicative of relative position over time and / or differences in relative position over time is considered motion data in the context of this disclosure.

[0014] According to an aspect, the motion sensor may include an accelerometer. The accelerometer may be configured to measure acceleration at least along the direction of travel of the elevator car inside the elevator shaft; for example, for a typical elevator installation, a single-axis accelerometer may be appropriate. It is understood that in a typical use case where the elevator shaft is essentially vertical to the surface of the earth, the accelerometer may be arranged such that the gravitational force measured by the accelerometer is not considered to be the acceleration of the elevator car, for example by biasing the accelerometer accordingly. The biasing may be obtained by biasing the accelerometer and / or by adjusting the offset value, which will be described in more detail herein with reference to the embodiments. Thus, the motion data indicative of acceleration may be indicative of the acceleration of the elevator car relative to the elevator shaft, which is considered to be stationary.

[0015] According to an aspect, the motion sensor may include a tracking sensor. The tracking sensor may be configured to detect the speed of the elevator car by detecting the movement of a surface, such as a surface fixedly mounted in the elevator shaft, relative to a tracking sensor fixedly mounted on the elevator car. The tracking sensor may be an optical tracking sensor. The tracking sensor may include a one-dimensional sensor, such as an optical encoder, such as an optical linear encoder. The tracking sensor may include a two-dimensional sensor, such as an image sensor that provides an image of the surface mounted in the elevator shaft suitable to be evaluated by digital image correlation (DIC) and / or optical flow analysis. Known two-dimensional sensors include optical flow sensors. Motion data indicative of the speed of the elevator car can be derived from an image, or a series of images captured over time, and evaluated as described above. Advantageously, an optical sensor based on a two-dimensional tracking sensor may be installed on the elevator car without the need to provide a coded surface in the shaft, for example, rails with textured surfaces, or even walls of the elevator shaft may be sufficient to record images of suitable quality to be evaluated by the two-dimensional tracking sensor. From the tracking sensors, motion data indicative of the relative position of the elevator car over time can be derived. Motion data indicative of speed and / or acceleration can be derived from the motion data indicative of the relative position of the elevator car.

[0016] According to aspects, the motion sensor types described herein, particularly accelerometers and optical tracking sensors, are small and generally readily available as integrated or semi-integrated components. Thus, several independent motion sensors, such as at least two independent motion sensors, may be provided without significant additional cost or space requirements. Beneficially, the sensors may be independent. Beneficially, the sensors may be provided in a single unit, for example, in a single board and / or combined housing. Advantages of providing more than one motion sensor are further described herein with reference to embodiments and include, among others, redundancy, the ability to perform sanity checks, and / or the ability to determine reliability parameters of each sensor. Furthermore, the sensors may be easily retrofitted into existing elevator installations, since the sensors may be installed on the elevator car, where service technicians generally have easy access.

[0017] According to an embodiment, a method for monitoring an elevator car includes utilizing and / or generating a dynamic system model of the elevator car in an elevator shaft. The dynamic system model may be generated by an evaluation unit. The dynamic system model describes the motion of the elevator car based on input variables. The input variables include position data and motion data. A dynamic system is known in the art and relates to a mathematical concept that functionally describes a point in the surrounding space over time. An elevator car traveling in an elevator shaft can be described as a system with a single degree of freedom along the length of the elevator shaft and therefore can be described by Newtonian mechanics. A description of Newtonian mechanics is provided in Paul A. Tipler, Physics for Scientists and Engineers, 4th Edition, 1999, p. 19-44, ISBN: 1-57259-673-2, which is incorporated herein to the extent of the description of the underlying concepts. The position, speed and acceleration of the elevator car are influenced by external forces applied to the system, for example by the elevator drive, the brake and gravity, and the motion of the elevator car may be described by interrelated values, position, speed and acceleration, at least in a constant or semi-constant state. The input variable position may be obtained directly from a position sensor providing position data. The input variables elevator car speed and / or acceleration may be obtained directly from a motion sensor providing motion data. The speed of the elevator car may be derived from the difference in the relative positions over time, in particular provided by a tracking sensor. The speed of the elevator car may be further derived from the motion data indicative of the acceleration of the elevator car, for example by integrating the acceleration over time. Similarly, the acceleration of the elevator car may be derivable from the motion data indicative of the speed of the elevator car. Thus, the position and motion data provided by the position and motion sensors may be utilized as input variables of a dynamic system model, which may be configured to represent the current state of the dynamic system, i.e. the elevator car traveling in the elevator shaft, based on the input variables.Similarly, assuming the dynamic system model has been initialized to model the movement of the elevator car and no dynamic system changes occur, the dynamic system model can be utilized to predict the position of the elevator car inside the elevator shaft at essentially any time, which can beneficially allow the system model to provide an estimated position independent of some or all of the motion or position data, particularly at times when position data from a position sensor is not available. Similarly, an estimated acceleration and / or an estimated speed can be provided by the dynamic system model.

[0018] According to an aspect, determining the estimated position includes evaluating the position data and the motion data with an estimation algorithm over a period of time. The estimation algorithm includes a representation of a dynamic system model. The evaluation unit may be configured to implement the estimation algorithm, for example, as a software program executed in a processor of the evaluation unit. The estimation algorithm may include an algorithm for simulating the dynamic system. The estimation algorithm may include an algorithm for approximating a position of the elevator car inside the elevator shaft based on Newtonian mechanics.

[0019] According to an embodiment, the estimation algorithm can include a sensor fusion algorithm. The sensor fusion algorithm can be configured to combine sensory data, such as position data and motion data. The sensor fusion algorithm can be configured to evaluate uncertainties in known and / or observed sensor values, such as uncertainties due to sensor noise, drift, or frequency of low data availability. For example, the sensor fusion algorithm can be based on a Bayesian network or even a convolutional neural network.

[0020] According to an embodiment, the estimation algorithm includes a Kalman filter or a variant of the Kalman filter, such as an extended Kalman filter or an unscented Kalman filter; such filters are referred to as Kalman filters. The Kalman filter is described in Kim, Y., & Bang, H. (2019); Introduction to Kalman Filter and Its Applications; Introduction and Implementations of the Kalman Filter; doi:10.5772 / intechopen.80600, which is incorporated herein to the extent of its explanation of the underlying concepts. In general, the Kalman filter may be a probabilistic mechanism for reasoning about a set of state variables at discrete time steps evolving under known dynamics, which are assumed to be linear and, for an elevator car moving in an elevator shaft, may be assumed to be based on Newtonian mechanics. The input variables, especially the motion data and position data, may be noisy. Based on the input variables, the Kalman filter may repeatedly apply a Gaussian identity to reason about the evolution of the hidden state, i.e., the state of the elevator car, including the position and / or speed of the elevator car. The Kalman filter may enable prediction of hidden states, in particular the position, speed and / or acceleration of the elevator car, based on previously observed input variables. The Kalman filter may be updated, in particular updated recursively, based on newly received input variables.

[0021] According to an aspect, the method includes determining an offset value indicative of an offset of the motion data, the evaluation unit being configured to determine the offset value indicative of the offset of the motion data, the offset value being generated such that a dynamic system model is adapted to a position of the elevator car as indicated by the position data.

[0022] According to aspects, the dynamic system model, particularly when implemented as a Kalman filter, may be configured, for example, by tuning the position data to consider it as lower error data, more reliable data, and / or absolute position data. As described herein, the offset value may be derived from the residuals of the motion data input variables obtained during the update phase of the Kalman filter.

[0023] According to aspects, the sensors described herein, particularly the combination of a sensor type laser distance sensor with one or more accelerometers, or one or more tracking sensors, may not function as an ideal sensor but may have technical limitations.

[0024] For example, a laser distance sensor as a position sensor can reliably provide position data with high accuracy, albeit at a limited speed. Furthermore, the accuracy of a laser distance sensor may be lower at high speed elevator cars and / or greatly reduce the frequency of reliable readings when the elevator car is moving. For example, an accelerometer as a motion sensor can provide motion data at high speed, but may drift over time, e.g. due to temperature changes. For example, a tracking sensor as a motion sensor may suffer from local drift or inaccuracies. Typical inaccuracies may include (intermittent) lack of detection of motion, resulting in erroneous low-speed readings. Similarly, changes in the distance between the surface tracked by the tracking sensor and the sensor may result in position-dependent drift. Any sensor type may suffer from short interruptions due to various external factors.

[0025] According to an aspect, potential drift or inaccuracy of the motion sensor can be mitigated by assuming that the position data provided by the position sensor is accurate and by iteratively adapting the dynamic system model based on the position data. Thus, the dynamic system model can include an offset value that is taken into account in combination with the motion data, so that the dynamic system model fits the elevator car position indicated by the position data. The offset value can be determined by considering the position data as absolute position data, i.e., position data indicative of the absolute position of the elevator car, and by determining the value by which the motion data needs to be adjusted, so that the estimated position determined by the dynamic system model at the time the position data is provided corresponds to the absolute position of the elevator car. In a typical situation, the offset data can correspond to the drift of the motion sensor such that the motion data can be utilized as an input variable of the dynamic system model when the offset is added or subtracted from a value representing the motion data.

[0026] According to an aspect, the method includes determining a reliability parameter of the sensor based on the offset value, and the evaluation unit is configured to determine the reliability parameter of the sensor based on the offset value. The offset value can indicate a discrepancy between the motion data provided by the motion sensor and a state of the dynamic system model. For example, the dynamic system model can be initialized and indicate that the elevator car is stationary, i.e., not moving, but the motion data erroneously provided by the accelerometer, e.g., due to a failure of the accelerometer, indicates a free fall of the elevator car. In an exemplary case, the input variable based on the motion data is offset by a large offset value that adapts the accelerometer to the position of the elevator car indicated by the position data, e.g., an offset corresponding to the gravity of the earth. The reliability parameter can be determined based on the offset value by defining a reliability threshold, and the reliability parameter can indicate that the motion sensor is unreliable or untrustworthy if the offset value exceeds the threshold. Similarly, the reliability parameter can be determined based on a frequency of adjustment of the offset value, a rate of change, and / or a sudden change in the offset value. Additionally or alternatively, a reliability indicator indicating that an offset value is outside a predefined acceptable level, e.g., exceeds a threshold, may indicate that the sensors providing the input variables of the dynamic system model are not in agreement with each other. A reliability indicator indicating a lack of agreement with each other may be suitable for determining a potentially unsafe condition without even determining whether or which particular sensor is providing erroneous data.

[0027] According to an aspect, in embodiments having multiple sensors, particularly multiple motion sensors, the reliability parameter may be further determined by comparing the offset values ​​of each sensor.

[0028] According to an embodiment, determining the offset values ​​is described for the motion data and / or motion sensors, but the reliability parameter may also be determined for the position sensors. Because the offset values ​​are determined such that the dynamic system model fits the elevator car position, a failed position sensor may cause the offset values ​​of all the motion sensors to be adjusted and the reliability parameter to indicate a potential failure of all the motion data and / or motion sensors. Thus, a condition in which most or all of the offset values ​​indicate that the motion sensors are considered unreliable or untrustworthy may correspond to a condition in which the position data and / or position sensors are unreliable, from which the reliability parameter for the position sensors may be determined.

[0029] According to an aspect, the position sensor, in particular the laser distance sensor, can acquire position data at a first frequency. Acquiring the position data can include determining a sensor reading, optionally processing the sensor reading, and / or communicating the position data based on the sensor reading to an evaluation unit. The first frequency can be low, where low frequencies are considered to be frequencies below 100 Hz, below 50 Hz, below 20 Hz, or even below 10 Hz. In some cases, the first frequency can be even lower, for example in some cases the position sensor can only provide position data at random intervals, with the interval for providing each position data potentially being several seconds. The first frequency can be variable, for example due to sensor limitations. For example, according to some embodiments, for some position sensor types, such as laser distance sensor types, that do not adequately compensate for Doppler shift, it can be beneficial to acquire position data only during slow travel or stoppage. Thus, the low frequency can be defined by the travel profile of the elevator car.

[0030] According to an embodiment, the motion sensor, in particular the accelerometer or tracking sensor, can acquire motion data at a second frequency. Acquiring the motion data can include determining a sensor reading, optionally processing the sensor reading, and / or transmitting the motion data to the evaluation unit based on the sensor reading. The second frequency can be high, where a high frequency is considered to be a frequency greater than 100 Hz, greater than 200 Hz, greater than 500 Hz, or even greater than 1 kHz. The second frequency can be variable, for example due to sensor limitations.

[0031] According to an aspect, the safety system may be configured to determine the estimated position at a third frequency, and the method may include determining the estimated position at the third frequency, the third frequency being higher than the first frequency. According to an embodiment, the third frequency may be any frequency, e.g., a frequency higher than the first frequency and the second frequency. Thus, the third frequency may be essentially limited by the speed of calculations required to provide an estimated position based on a dynamic system model, e.g., an estimation algorithm. According to a preferred embodiment, the dynamic system model may be updated, e.g., essentially at the second frequency, or at a frequency between the first frequency and the second frequency, by performing an update operation of the estimation algorithm based on newly available movement data and / or updating the dynamic system model. Beneficially, the dynamic system model may be updated as position data or movement data become available, and the estimated position may be determined based on the updated dynamic system model. This may beneficially provide an accurate estimated position at a sufficiently high frequency, e.g., essentially at the second frequency, while limiting the computational load.

[0032] Beneficially, the methods and systems described herein allow for accurate determination of elevator car position, speed, and acceleration during operation of the elevator installation. Different types of sensors are utilized, and technical limitations of each sensor type can be at least partially overcome by generating a dynamic system, i.e., a dynamic system model that utilizes position and motion data to describe the elevator car's motion in the elevator shaft. In some embodiments, the safety system can be safety rated. The safety rating of the safety system can be higher than some, or even all, of the individual sensors utilized in the safety system. This can beneficially allow, for example, to combine different sensor types according to the requirements of a particular type of elevator installation, thereby increasing flexibility while maintaining high safety standards. Beneficially, reliability parameters of the sensors are determined, which can be utilized, for example, to determine potentially unsafe conditions.

[0033] Reference will now be made in detail to various embodiments, one or more examples of which are illustrated in the drawings. In the following description of the drawings, like reference numerals refer to like components. Generally, only the differences with respect to individual embodiments will be described. Each example is provided by way of explanation and is not meant to be limiting. Moreover, features illustrated or described as part of one embodiment may be used on or in conjunction with other embodiments to yield yet a further embodiment. It is intended that the description include such modifications and variations. [Brief description of the drawings]

[0034] [Figure 1] 1 shows a schematic elevator installation according to an embodiment; [Diagram 2] FIG. 2 shows a schematic diagram illustrating the evaluation of sensor data. [Diagram 3] 1 shows a timeline illustrating the evaluation of sensor data. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0035] 1 shows an elevator installation 100 having an elevator shaft 110 and an elevator car 120 movably mounted in the elevator shaft 110. The elevator car 120 is suspended on cables driven by a drive system. For clarity, some components of the elevator installation, such as doors or counterweights, have been omitted from the figure. Additional drive systems other than a cable-based drive system may be suitable, and the described subject matter is not limited to the type of drive system shown in the figure.

[0036] The elevator installation 100 includes a position sensor 140. In an embodiment, the position sensor 140 is a laser distance sensor configured to emit a laser beam 144, receive a reflection of the laser beam 144, and determine the distance between the position sensor 140 and a reflector by measuring the time that the laser beam 144 travels between emitting and receiving the laser beam. The reflector 142 is provided at a reference point at the bottom of the elevator shaft 110, but according to an embodiment, this reflector may be optional, i.e., the reference point may be formed from the surface of the elevator shaft 110. The reflector may be beneficial in embodiments with long elevator shafts, such as buildings with elevator installations spanning more than five floors, to improve the quality of the signal of the reflected laser beam 144.

[0037] 1, position sensor 140 may be mounted at the bottom of the elevator car and emit laser beam 144 toward the bottom of the elevator shaft, although alternative mounting locations, such as, for example, the roof or side of elevator car 120, may be suitable as well. Similarly, a reference point, optionally including reflector 142, may be provided anywhere in the elevator shaft, in particular at the top of the shaft adjacent the highest or lowest landing door, and / or on a wall of elevator shaft 110 adjacent or proximate to the top or bottom of elevator shaft 110.

[0038] As shown in Fig. 1, elevator installation 100 includes motion sensor 130, which is a tracking sensor for detecting the speed of elevator car 120. Motion sensor 130 is mounted on elevator car 120 and moves with the elevator car. Motion sensor 130 is provided near rail 132, which is fixedly mounted to elevator shaft 110. Rail 132 serves as a reference surface for motion sensor 130. According to an embodiment, motion sensor 130 may comprise a linear optical encoder, and rail 132 may be optically encoded with a surface pattern, such as, for example, a surface pattern comprising incremental lines.

[0039] According to an embodiment, the motion sensor 130 may comprise a two-dimensional optical tracking sensor suitable for digital image correlation (DIC) and / or optical flow analysis, as described in the general part of this disclosure. Beneficially, in an embodiment utilizing a two-dimensional tracking sensor, a non-encoded rail 132 may be utilized as the surface tracked by the tracking sensor, i.e., tracking may be based on variations in the inherent surface texture of the rail. Beneficially, the rail 132 may be a rail of an existing elevator system, such as a guide rail. Beneficially, instead of the rail 132, any essentially flat surface of the elevator shaft, such as a wall, may be suitable for use with the two-dimensional tracking sensor. According to an embodiment, the motion sensor 130 may include a light emitter, such as a light emitting diode or a laser diode, for illuminating the surface tracked by the optical tracking sensor.

[0040] As shown in FIG. 1, the elevator installation 100 includes a motion sensor 134. The motion sensor 134 includes an accelerometer. In particular, the accelerometer does not require interaction with a reference point or a trackable surface provided in the elevator shaft 110, so the motion sensor 134 can be installed at any point in or on the elevator car 120. The accelerometer can be configured to sense the acceleration of the elevator car 120 inside the elevator shaft 110 in the direction of travel, i.e., essentially vertical. The accelerometer can thus measure the acceleration corresponding to the gravity of the earth while the elevator car is stopped or moving steadily, and can measure deviations from this acceleration when the elevator car is accelerated or decelerated.

[0041] As shown in FIG. 1 and indicated by the dotted lines, each of the position sensor 140 and the motion sensors 130, 134 are communicatively connected to an evaluation unit 150. Although the evaluation unit 150 is shown in FIG. 1 as being provided on the elevator car, the evaluation unit 150 may also be provided in a different location, for example, inside the elevator shaft, in a machine room, or even in a remote location. The evaluation unit 150 may include a processor, such as a microprocessor, a field programmable gate array, and / or a central processing unit, for executing a software program. The evaluation unit 150 may be configured to receive input variables and may include a memory for storing the software program and / or the input variables, the input variables including position data and motion data as described herein. The software program, when executed in the processor, may be configured to generate a dynamic system model of the elevator car 120 moving inside the elevator shaft 110, as described herein. The software program, when executed in the processor, may include an estimation algorithm, as described herein. The software program, when executed in the processor, may be configured to perform the methods described herein, in particular in determining an estimated position of the elevator car, determining an offset value indicative of an offset of the motion data, and determining a reliability parameter of the sensor based on the offset value. The evaluation unit 150 may be configured to receive the motion data and position data provided by the position sensor 140 and the motion sensors 130, 134 via a communication connection. Thus, the evaluation unit 150 may comprise one or more interfaces for establishing the communication connection. The evaluation unit 150 may be further configured to provide output data including the reliability parameter of the sensor and, optionally, the estimated position of the elevator car, and / or data derived from the reliability parameter of the sensor. The output data may further include additional data derivable from the dynamic system model, such as data indicative of the speed of the elevator car and / or the acceleration of the elevator car.The output data may be provided via a communication connection (not shown) to further components of the elevator installation, such as a control unit and / or a safety system (not shown). The safety system may include an evaluation unit 150.

[0042] As shown in FIG. 1, the elevator system 100 has a safety system including a position sensor 140, an evaluation unit 150, a motion sensor 130 which is a tracking sensor, and a motion sensor 134 which is an accelerometer.

[0043] Alternatively, the safety system may include a position sensor, such as position sensor 140, and a single motion sensor, such as either motion sensor 130 or motion sensor 134. Similarly, the safety system may include two or more motion sensors, such as at least two motion sensors, such as motion sensor 130 or motion sensor 134, and the two or more motion sensors may be of the same type. In a useful example, which will be described in more detail with reference to FIG. 2, the safety system may include two motion sensors 134, e.g., two independent accelerometers. Similarly, in a further example, the safety system may include two motion sensors 130, e.g., two independent tracking sensors.

[0044] As shown in Fig. 1, the components of the safety system described herein may be separate components, i.e. components that can be provided separately in different locations. Beneficially, in particular the motion sensors 130 and 134 and / or the evaluation unit can be combined in a single physical unit, e.g. on a single board and / or inside a combined housing. Similarly, even the position sensor 140 can be included in a single unit, e.g. in a configuration with one or more motion sensors 134. A safety system combined as a single unit can beneficially reduce the effort required for installation and / or retrofitting of the safety system.

[0045] 2, a schematic diagram is shown illustrating an evaluation of sensor data 200. The evaluation 200 illustrated in FIG. 2, in particular blocks 230a, 230b, 240a, 240b and / or 250a, 250b, may be performed by an evaluation unit such as evaluation unit 150.

[0046] Block 210 represents acquisition of position data by a position sensor, such as, for example, position sensor 140. Blocks 220a and 220b represent acquisition of motion data by independent motion sensors, such as, for example, two independent motion sensors, such as motion sensor 134. Although this embodiment is described with a motion sensor including an accelerometer providing motion data indicative of the acceleration of the elevator car, alternative embodiments may include various types and combinations of motion sensors and may be suitable for various types and combinations of motion data. Similarly, aspects of the embodiments not related to deriving information from two or more independent motion data may similarly be implemented for embodiments having one position sensor and one motion sensor, i.e., a single evaluation stream may be utilized.

[0047] As shown in Fig. 2, the embodiment has two independent assessment streams or channels including blocks 220a-250a and 220b-250b. The position data acquired in block 210 is shared between the two independent assessment streams. In yet further embodiments, the assessment 200 may be performed for only one assessment stream, or even for more than two assessment streams, i.e., further assessment streams essentially identical to the assessment stream shown in Fig. 2 may be added. The assessment streams may operate independently, in particular asynchronously.

[0048] The motion data acquired in the blocks 220a, 220b are transferred to the blocks 230a, 230b via the communication connections 222a, 222b. The blocks 230a, 230b may be filter blocks, sensor fusion blocks, and / or estimation algorithm blocks. Similarly, the position data acquired in the block 210 are transferred to the blocks 230a, 230b via the communication connections 212a, 212b. According to an embodiment, the blocks 230a, 230b include a sensor fusion algorithm, in particular a Kalman filter, for generating a dynamic system model of the elevator car 120 moving in the elevator shaft 110. The motion data is indicative of the motion of the elevator car and may include at least one of an elevator car acceleration and / or an elevator car speed. The position data may be indicative of the position of the elevator car and may include position data as described herein. Thus, in blocks 230a, 230b, a dynamic system model can be initialized to describe the motion of the elevator car based on the motion and sensor data provided by blocks 210, 220a, and 220b.

[0049] At blocks 230a, 230b, output data is generated based on the initialized dynamic system model. In an embodiment, the output data includes an estimated elevator car position and an offset value indicating an offset of the motion data, as described herein. In addition to or instead of the estimated position, the output data may include an estimated elevator car speed, an estimated elevator car acceleration, an estimated change in elevator car acceleration over time, and / or a confidence indicator, such as an (estimated) error margin or (estimated) standard deviation of each of the output data.

[0050] According to an embodiment, additional input variables may be transferred to blocks 230a, 230b. For example, additional position data from other sensors provided in the elevator installation may be available, such as position data derivable from door sensors when the elevator car is stationary at the landing doors or when it passes through the landing doors during travel. Thus, in addition to the position data obtained in block 210, additional position data may be available.

[0051] According to an embodiment, the output data may be utilized directly, for example, by an elevator system controller (not shown) communicatively connected to one or more of blocks 230a, 230b to control operation of the elevator system based on the output data. For example, the estimated position and estimated speed may be utilized to control an elevator drive to precisely align the elevator car with the landing doors.

[0052] According to an embodiment, the evaluation 200 may further be used to determine the safety status of the elevator installation. Thus, the output data generated by the method described herein may be used to determine the safety status of the elevator installation. As shown in FIG. 2, the output data is transferred to the safety blocks 240a, 240b via the communication connections 232a, 232b. Furthermore, the position data and the motion data acquired by the blocks 210, 220a, 220b may be transferred to the safety blocks 240a, 240b via the communication connections 224a, 224b, and 214. Thus, the safety blocks 240a, 240b may individually evaluate the data to detect potentially unsafe conditions and further cross-correlate the transferred data to evaluate the data to detect potentially unsafe conditions. Furthermore, the evaluation results of the independent safety blocks 240a, 240b may be transferred between the safety blocks 240a, 240b (not shown) and compared with the evaluation results of the other safety blocks 240a, 240b. This allows one to determine whether the unsafe condition was detected due to the elevator system being in an unsafe condition or due to an erroneous reading of the sensor in an otherwise safe condition.

[0053] According to an embodiment, the safety blocks 240a, 240b may be configured to evaluate the position data and the motion data, particularly by performing a sanity check on the position data and / or motion data acquired in the blocks 210, 220a, and 220b. The results of the evaluation may be included in the reliability parameters of the sensors. The motion data and / or sensor data received via the communication connections 224a, 224b, and 214 may be evaluated based on the frequency of data availability. For example, it may be determined whether the sensor providing the data provides the data at an expected frequency. A lower than expected frequency, or a lack of data, may indicate a sensor failure. Additionally or alternatively, the position data may be further evaluated based on unexpected readings. For example, a sudden change in position, i.e., a "jump," e.g., a change in position indicated by the position data exceeding a predefined threshold, may indicate a position sensor failure.

[0054] According to an embodiment, the safety blocks 240a, 240b may be configured to evaluate the output data, in particular by performing a sanity check on the output data acquired by the blocks 230a and 230b and received via the communication connections 232a, 232b. A reliability parameter of the sensor based on the offset value is determined. A motion sensor having a high offset value may be considered unreliable and / or an offset value exceeding a predefined threshold may be considered unreliable or untrustworthy. The reliability parameter may be the output data of the safety blocks 240a, 240b. Similarly, further parameters, such as any data received by the safety blocks 240a, 240b, may be included in the output data of the safety blocks 240a, 240b. Furthermore, discrepancies between the data received by the safety blocks 240a, 240b may be determined and included in the output data of the safety blocks 240a, 240b.

[0055] As shown in FIG. 2, the output data of the safety blocks 240a, 240b may be transferred to the control blocks 250a, 250b via the communication connections 242a, 242b. The control blocks 250a, 250b may be included in a safety system. Alternatively, the control blocks 250a, 250b may be provided in a controller of the elevator installation. Based on the input data received via the communication connections 242a, 242b, the control blocks 250a, 250b may perform certain control actions, such as logging a sensor reliability warning or error, reducing the elevator car speed to a safe speed, applying the equipment brakes, stopping the elevator car, or putting the elevator installation into a fail-safe state. The control actions may be performed when one or both of the safety blocks 240a, 240b provide a sensor reliability parameter that indicates a sensor failure or an unreliable sensor.

[0056] A control action may be further executed if any of the parameters position, speed and / or acceleration exceed a predefined safe value, e.g. exceed a predefined threshold. For example, the speed or acceleration of the elevator car may exceed a predefined threshold. For example, the position of the elevator car may be, for example, closer to the shaft top or bottom than a position defined as safe or a position defined as safe at a given speed. Thus, the output data may include any of the parameters (estimated) acceleration, (estimated) speed, (estimated) position, as well as further parameters described herein, in addition to the sensor reliability parameters, and may be evaluated by the control blocks 250a, 250b to detect a potentially unsafe condition.

[0057] If a discrepancy between the parameters provided to one safety block relative to the other safety block is detected, a control action may be executed. The position, velocity, and / or acceleration parameters may include both directly measured values, i.e., sensor data, and estimated values ​​based on a dynamic system model and / or estimated by estimation algorithms of blocks 230a, 230b.

[0058] Beneficially, referring for example to FIG. 2, the assessment described herein allows for detecting potentially unsafe conditions or component failures, such as sensor failure or sensor unreliability, not only by analyzing raw sensor data, but also by considering the sensor values ​​in the context of a dynamic system model describing the elevator car motion. This can facilitate detection of faults that cause errors. Based on offset values ​​determined for the motion sensor data, it may be possible to identify whether either the motion sensor or the position sensor provides unreliable data based on the increase in offset values ​​required to fit the sensor data to the dynamic system model. Unreliable sensors may be identified even before a complete sensor failure occurs, thus increasing safety and passenger comfort, for example, by allowing a technician to identify and replace one or more unreliable sensors even before further potential problems arise.

[0059] Referring now to FIG. 3, a timeline 300 illustrating the evaluation of sensor data over a period of time according to an embodiment will be described. The timeline 300 shows a series of operations 310a to 310c. As previously mentioned, in an exemplary embodiment, the dynamic system model may be generated by an estimation algorithm such as a Kalman filter, and although the embodiment is described with reference to a Kalman filter, other estimation and / or sensor fusion algorithms may be utilized. As previously mentioned, in an exemplary embodiment, the motion data may be available at a higher frequency than the position data. In some embodiments, an accurate estimation of the elevator car's position may be possible based only on motion data of an extended duration, e.g., several seconds, or even several minutes. In the embodiment shown in FIG. 3, the motion data includes acceleration data, although motion data indicative of the speed of the elevator car may be utilized instead. The operations described with reference to the timeline 300 may be implemented in a system such as the safety system described with reference to FIG. 1 and / or as an evaluation stream of the evaluation stream described with reference to FIG. 2.

[0060] In operation 310a, the Kalman filter is initialized and iteratively updated based on the availability of motion data indicative of the motion, i.e., acceleration, of the elevator car. In this context, updating describes the update step of the Kalman filter, i.e., adapting the dynamic system model to fit the measured conditions based on the new motion data. According to an embodiment, each time new motion data becomes available, an estimated position of the elevator car is determined based on the updated dynamic system model, i.e., the estimated position is iteratively determined.

[0061] In operation 330a, position data is available that indicates the absolute position of the elevator car relative to the elevator shaft. The position data is used to update a Kalman filter and generate an estimated position based on the position data and / or both the motion data and the position data of the input variables.

[0062] Before the Kalman filter is updated, a health check 320a may be performed. The health check may include comparing the estimated position data obtained from the Kalman filter to position data indicative of the absolute position of the elevator car. The health check may include comparing the estimated position to the absolute position indicated by the position data and checking whether the estimated position correlates with the absolute position, for example, by checking whether the estimated position and the absolute position deviate by less than a predefined threshold. For example, if the estimated position deviates from the absolute position, a sensor reliability parameter may be generated that indicates a potential fault in one or both of the motion and position sensors.

[0063] Additionally or alternatively, sanity check 322a may be performed as described for sanity check 320a after the Kalman filter has been updated in operation 330a or after the offset value has been determined as described for operation 340a.

[0064] The dynamic system model is further updated in operation 340a to fit the absolute position by determining an offset value indicative of an offset of the motion data based on the position data deemed to be indicative of the absolute position.

[0065] After the offset value is determined in operation 340a, a sanity check 322a is performed. The optional operations described for sanity check 320a may also be performed for sanity check 322a, but in addition, it is determined whether the offset value exceeds a threshold, e.g., a predefined threshold. In connection with this aspect, additionally or alternatively, it may be determined whether the rate of change of the offset value exceeds a predefined threshold, e.g., as described in the general section of this disclosure. If the threshold is exceeded, a sensor reliability parameter may be generated that indicates a potential failure in one or both of the motion and position sensors. Additionally, a fail-safe state may be entered in which no further position estimates are generated, and / or control actions may be performed, such as those described for control blocks 250a, 250b.

[0066] If the sanity checks 320a, 322a indicate that the estimated position correlates with the absolute position derived from the position data and the offset value does not exceed the threshold, a safety system or method implementing evaluation of sensor data according to an embodiment may proceed to repeatedly perform the operations described herein, i.e., repeatedly estimating the position in operation 310b as described for operation 310a, and, as new position data becomes available, performing operations 320a, 330b, 340b, and 322b as described for operations 320a, 330a, 340a, and 322a. This process may be repeated essentially indefinitely.

[0067] Beneficially, in systems and methods for performing assessment 200, particularly according to the operations described with reference to timeline 300, estimated position data is available more frequently based on motion sensor data than absolute position data provided by a position sensor. Similarly, safety-related parameters speed and acceleration may be more reliably monitored based on estimated parameters combined with sensor reliability parameters.

Claims

1. A method for monitoring an elevator car (120) inside an elevator shaft (110), the method being: To obtain position data indicating the position of the elevator car (210), To acquire motion data showing the movement of the elevator car (220a, 220b), The estimated position of the elevator car is determined from a dynamic system model (230a, 230b), wherein the dynamic system model describes the motion of the elevator car based on input variables, and the input variables include position data and motion data. The method includes, This involves determining an offset value that indicates the offset of the motion data, such that the offset value is generated so that the dynamic system model fits the position of the elevator car indicated by the position data. Determining the sensor reliability parameters based on the offset value, To provide output data including sensor reliability parameters and A method characterized by further comprising:

2. The method according to claim 1, wherein determining the estimated position includes evaluating positional and motion data using an estimation algorithm over a period of time, the estimation algorithm including a representation of a dynamic system model.

3. The method according to claim 2, wherein the estimation algorithm includes a sensor fusion algorithm and / or a Kalman filter.

4. The method according to claim 1, wherein acquiring motion data (220a, 220b) includes acquiring motion data using at least two independent sensors.

5. The method according to claim 4, further comprising independently evaluating the exercise data.

6. The method according to claim 1, wherein the motion data indicates at least one of the speed of the elevator car and / or the acceleration of the elevator car.

7. The method according to claim 1, wherein the position data indicates the absolute position of the elevator car within the elevator shaft.

8. The location data indicates the absolute position of the elevator car, and the method is The estimated position of the elevator car is repeatedly determined based on motion data. After acquiring the location data, the operation proceeds from a.) to c.), i.e. a.) Adapt the dynamic system model to fit the absolute position and determine whether the offset value exceeds a threshold. b.) Comparing the estimated position with the absolute position indicated by the position data, c.) - The estimated position correlates with the absolute position derived from the position data, and - The offset value and / or the rate of change of the offset value do not exceed the threshold. Under these conditions, the estimated position of the elevator car is repeatedly determined based on motion data. To do The method according to claim 1, further comprising:

9. A safety system for monitoring elevator cars inside elevator shafts, A position sensor (140) configured to acquire position data (210) indicating the position of the elevator car, Motion sensors (130, 134) configured to acquire motion data (220a, 220b) indicating the movement of the elevator car. The evaluation unit (150) is, It receives input variables including motion data and position data, The estimated position of the elevator car is determined from the dynamic system model, which describes the motion of the elevator car based on input variables, including position data and motion data. An evaluation unit (150) configured as follows: The evaluation unit (150) is equipped with the following: Determine the offset value that indicates the offset of the motion data, The sensor reliability parameters are determined based on the offset value. It provides output data including sensor reliability parameters. The offset value is generated so that the dynamic system model fits the position of the elevator car indicated by the position data. A safety system characterized by being further configured in such a way.

10. The safety system according to claim 9, wherein the evaluation unit (150) is configured to implement an evaluation algorithm, the evaluation algorithm is configured to evaluate position data and motion data over a period of time to determine an estimated position and offset value.

11. The position sensor (140) is configured to acquire position data at a first frequency. The motion sensors (130, 134) are configured to acquire motion data at a second frequency. The first frequency is lower than the second frequency. The safety system according to claim 9, wherein the safety system is configured to determine the estimated position at a third frequency higher than the first frequency.

12. The safety system according to claim 9, wherein the position sensor (140) is configured to detect the distance between the elevator car and a reference point inside the elevator shaft.

13. The safety system according to claim 9, wherein the position sensor (140) includes a laser distance sensor.

14. Motion sensors (130, 134) An accelerometer for detecting the acceleration of the elevator car, and Tracking sensor for detecting the speed of the elevator car The safety system according to claim 9, comprising at least one of the following.

15. Use of output data generated by the method of any one of claims 1 to 8 or by a safety system according to any one of claims 9 to 14 for determining the safety status of an elevator system, wherein the output data includes one or more of the estimated position, estimated velocity, and / or estimated acceleration of the elevator car.

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