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

Abstract

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 motion of the elevator car, and determining an estimated position of the elevator car according to a dynamic system model. The dynamic system model describes movement of the elevator car based on the input variables. The input variables include position data and motion data. The method further includes determining an offset value indicative of a degree of motion data offset, where the offset value is generated such that the dynamic system model fits a position of the elevator car 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 a safety system for monitoring an elevator car in an elevator shaft, in particular for reliably determining the elevator car position, velocity and / or acceleration based on a plurality of sensor inputs. Aspects of the invention relate to implementing an estimation algorithm to estimate the position, velocity and / or acceleration of the elevator car and to determine a sensor reliability parameter. Background Art

[0002] Elevator installations are known in the art. An elevator comprises an elevator shaft or a hoistway and an elevator car movably arranged in the elevator shaft. An elevator suitable for transporting passengers must generally meet high safety standards. For safety reasons, a safety system may monitor and estimate parameters of an elevator car traveling in the elevator shaft. Such parameters may include acceleration, speed and / or position of the elevator car. In the event that a parameter falls outside a safe range, the safety system may indicate an unsafe state, and the elevator installation may respond by, for example, applying brakes or causing the elevator car to travel at a reduced speed. The acceptable range of a parameter may be defined according to the values ​​of other parameters. For example, the acceptable speed towards the end of the hoistway may be reduced relative to the acceptable speed in the middle of the hoistway.

[0003] By combining different sensor types, various safety-related parameters can be measured and estimated by the safety system. However, the reliability or accuracy of certain sensor types may be limited, which, if estimated independently, may lead to inaccurate estimates of the state of the elevator installation, which may lead to false alarms, or even unsafe conditions.

[0004] Furthermore, different sensors used in conventional elevator facilities (eg, an overspeed governor or an overtravel protection system) are usually installed at different locations within the elevator facility, and thus are difficult to install or maintain.

[0005] Therefore, it would be beneficial to provide an improved system or method for monitoring an elevator car within an elevator shaft.The present invention at least partially solves the above problems. Summary of the invention

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

[0007] According to one aspect, a method of monitoring an elevator car in an elevator shaft is described. The method includes acquiring position data indicating a position of the elevator car, acquiring motion data indicating a motion of the elevator car, and determining an estimated position of the elevator car based on 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 also includes determining an offset value indicating a degree of offset of the motion data, wherein the offset value is generated so that the dynamic system model fits the position of the elevator car 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 one aspect, a safety system for monitoring an elevator car in an elevator shaft is described. The safety system includes a position sensor, a motion sensor, and an estimation unit, wherein the position sensor is configured to obtain position data indicating the position of the elevator car, and the motion sensor is configured to obtain motion data indicating the motion of the elevator car. The estimation unit is configured to receive input variables including motion data and position data, and determine an estimated position of the elevator car according to a dynamic system model. The dynamic system model describes the motion of the elevator car based on the input variables. The input variables include position data and motion data. The estimation unit is also configured to determine an offset value indicating a degree of offset of the motion data. The offset value is generated so that the dynamic system model fits the position of the elevator car indicated by the position data. The estimation unit is also configured to determine a sensor reliability parameter based on the offset value and provide output data including the sensor reliability parameter.

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

[0010] Advantageously, the position data of the elevator car may be determined at any potential position within the elevator shaft, and in particular may not be limited to being determined only at a specific position of the elevator car within the elevator shaft, such as when the elevator car is located near a landing door. Thus, the position sensor may be configured for sensing the position of the elevator car at substantially any position of the elevator car within the elevator shaft. Additionally or alternatively, the position data may be determined under conditions where the position sensor can provide accurate readings, such as when the elevator car is traveling slowly or even when the elevator car is stationary.

[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 arranged on the elevator car, for example, on or near the top or bottom of the outside of the elevator car, and may have a field of view including a reference point within the elevator shaft (for example, at the top or bottom of the elevator shaft). According to an embodiment, a reflector, such as a retroreflector or a reflective surface or a mirror-like surface, may be arranged at the reference point, however, if the reflectivity of the reference point is sufficient for a particular elevator facility, the reflector may be optional and may be omitted. 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 measurement. Additionally or alternatively, a distance sensor, in particular an optical distance sensor, using triangulation, multi-frequency phase shifting and / or interferometry may be utilized without exceeding the scope of the present disclosure.

[0012] According to an alternative embodiment, the positions of the distance sensor and the reference point may be inverted, for example the distance sensor may be arranged at a fixed point in the elevator shaft and the reference point may be arranged on the elevator car.

[0013] According to one aspect, obtaining motion data indicating the motion of an elevator car is described. The motion data may be obtained by a motion sensor. For example, the motion data may indicate the rate or speed of the elevator car and / or the acceleration of the elevator car. Motion data indicating that the elevator car is stationary (i.e., has zero speed) and that the elevator car has no acceleration is considered as motion data indicating the motion of the elevator. Motion data indicating the change of the acceleration of the elevator car over time is considered as motion data. Data indicating a measurable parameter that is not related to the linear motion of the elevator car within the elevator shaft (e.g., vibration of the elevator car that can be measured by an accelerometer) is generally not considered as motion data. The motion data may include data representing the relative motion of the elevator car, such as information defining the relative motion relative to the position of the elevator car. For example, the motion data may include values ​​indicating the difference between the position of the elevator car at different points in time and / or the distance traveled between the points in time. Therefore, in the context of the present disclosure, a series of motion data indicating the relative position over time and / or the difference in relative position over time is considered as motion data.

[0014] According to an aspect, the motion sensor may include an accelerometer. The accelerometer may be configured to measure at least one acceleration along the direction of travel of the elevator car in the elevator shaft, for example for a typical elevator installation a single axis accelerometer may be suitable. It will be appreciated that in a typical use case where the elevator shaft is arranged substantially vertically relative to the earth's surface, the accelerometer may be arranged such that the gravity measured by the accelerometer is not considered as an acceleration of the elevator car, for example by biasing the accelerometer accordingly. The bias may be obtained by biasing the accelerometer and / or by adjusting an offset value, which will be explained in more detail herein with reference to the embodiments. Thus, the motion data indicating an acceleration may indicate the acceleration of the elevator car relative to the elevator shaft, which is considered to be static.

[0015] According to an aspect, the motion sensor may comprise a tracking sensor. The tracking sensor may be configured for sensing the velocity of the elevator car, in particular by sensing the motion of a surface, for example a surface fixedly arranged in the elevator shaft, relative to the tracking sensor fixedly arranged on the elevator car. The tracking sensor may be an optical tracking sensor. The tracking sensor may comprise a one-dimensional sensor, for example an optical encoder, for example an optical linear encoder. The tracking sensor may comprise a two-dimensional sensor, for example an image sensor, which provides an image of a surface arranged in the elevator shaft, suitable for estimation by digital image correlation (DIC) and / or optical flow analysis. Known two-dimensional sensors include optical flow sensors. Motion data indicating the velocity of the elevator car may be derived from one image or a series of images captured over time and estimated as described above. Advantageously, an optical sensor based on a two-dimensional tracking sensor may be mounted on the elevator car without providing a coded surface in the shaft, for example a track with a textured surface, or even the wall of the elevator shaft, being sufficient for recording images of suitable quality to be estimated by the two-dimensional tracking sensor. Motion data indicating the relative position of the elevator car over time may be derived from the tracking sensor. The motion data indicative of velocity and / or acceleration may be derived from the motion data indicative of the relative position of the elevator cars.

[0016] According to one aspect, the types of motion sensors described herein (particularly accelerometers and optical tracking sensors) are relatively small and are generally readily available as integrated or semi-integrated components. Thus, a plurality of independent motion sensors, for example at least two independent motion sensors, may be provided without significantly increasing cost or space requirements. Advantageously, the sensors may be independent. Advantageously, the sensors may be provided in a single unit, for example on a single board and / or in a combined housing. The benefits of providing a plurality of one motion sensors, particularly including redundancy, the ability to perform sanity checks and / or determine reliability parameters for each sensor, will be further described herein with reference to embodiments. Furthermore, the sensors may be easily retrofitted to existing elevator installations, since the sensors may be mounted on the elevator car, which is generally easily accessible to a maintenance technician.

[0017] According to one aspect, a method for monitoring an elevator car includes utilizing and / or generating a dynamic system model of an elevator car in an elevator shaft. The dynamic system model may be generated by an estimation 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. Dynamic systems are known in the art and involve mathematical concepts that functionally describe points in an environment space over time. An elevator car traveling in an elevator shaft may be described as a system having a single degree of freedom along the length of the elevator shaft and may therefore be described using Newtonian mechanics. A description of Newtonian mechanics is provided in Paul A. Tipler, Physics for Scientists and Engineers, 4th edition, 1999, pp. 19-44, ISBN: 1-57259-673-2, which is incorporated herein to the extent that the basic concepts are described. The position, velocity and acceleration of the elevator car are affected by external forces, such as external forces applied to the system by, for example, the elevator drive, brakes and gravity, and the movement of the elevator car at least in a constant state or a semi-constant state can be described by mutually related position values, velocity values ​​and acceleration values. The input variable position can be obtained directly from the position sensor that provides position data. The input variable velocity and / or acceleration of the elevator car can be obtained directly from the motion sensor that provides motion data. The speed of the elevator car can be derived from the difference in relative position over time (particularly provided by a tracking sensor). The speed of the elevator car can also be derived from the motion data indicating the acceleration of the elevator car, for example by integrating the acceleration over time. Similarly, the acceleration of the elevator car can be derived from the motion data indicating the speed of the elevator car. Therefore, the position data and motion data provided by the position sensor and the motion sensor can be used as input variables of the dynamic system model, and the dynamic system model can 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. Likewise, assuming that the dynamic system model has been initialized to model the motion of the elevator car and that the dynamic system has not changed, the dynamic system model can be used to predict the position of the elevator car within the elevator shaft at substantially any point in time, which can advantageously allow the system model to provide an estimated position independent of some or all motion data or position data, particularly at points in time when position data is not available from the position sensor. Likewise, the dynamic system model can provide an estimated acceleration and / or an estimated velocity.

[0018] According to an aspect, determining the estimated position comprises estimating the position data and the motion data over a period of time using an estimation algorithm. The estimation algorithm comprises a representation of a dynamic system model. The estimation unit may be configured for implementing the estimation algorithm, for example as a software program to be executed on a processor of the estimation unit. The estimation algorithm may comprise an algorithm for simulating a dynamic system. The estimation algorithm may comprise an algorithm for approximating the position of the elevator car within the elevator shaft based on Newtonian mechanics.

[0019] According to one aspect, the estimation algorithm may include a sensor fusion algorithm. The sensor fusion algorithm may be configured to combine sensed data, such as position data and motion data. The sensor fusion algorithm may be configured to estimate known and / or observed sensor value uncertainties, such as sensor noise, drift, or uncertainties due to low data availability frequency. For example, the sensor fusion algorithm may be based on a Bayesian network, or even on a convolutional neural network.

[0020] According to one aspect, the estimation algorithm comprises a Kalman filter or a variant of a Kalman filter, such as an extended Kalman filter or, for example, an unscented Kalman filter; such a filter is referred to as a Kalman filter. Kalman filtering is described in Kim, Y., and 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 that the basic concepts are described. In general, a Kalman filter can be a probabilistic mechanism for reasoning about a sequence of state variables of discrete time steps evolving under known mechanics, which are assumed to be linear and, for an elevator car moving in an elevator shaft, can be assumed to be based on Newtonian mechanics. The input variables, in particular the motion data and the position data, may be noisy. The Kalman filter may reason about the evolution of hidden states, i.e. the state of the elevator car including the position and / or velocity of the elevator car, based on the input variables by repeatedly applying the Gaussian identity. The Kalman filter may allow predicting hidden states, in particular the position, velocity and / or acceleration of the elevator car, based on previously observed input variables. The Kalman filter may be updated, in particular recursively, based on newly received input variables.

[0021] According to an aspect, the method comprises and the estimation unit is configured for determining an offset value indicating a degree of offset of the motion data. The offset value is generated such that the dynamic system model fits the position of the elevator car indicated by the position data.

[0022] According to one aspect, the dynamic system model (particularly when implemented as a Kalman filter) can be configured, for example by tuning, to treat the position data as low-error, high-reliability and / or absolute position data. As described herein, the offset value can be derived from the residual of the motion data input variable obtained in the update phase of the Kalman filter.

[0023] According to one aspect, the sensors described herein, in particular the sensor type combination of a laser distance sensor and one or more accelerometers or one or more tracking sensors, may not function as an ideal sensor but may present technical limitations.

[0024] For example, a laser distance sensor as a position sensor can reliably provide position data with high accuracy, but at a limited rate. Furthermore, if the elevator car is in motion, the accuracy of the laser distance sensor may be lower at high speeds of the elevator car, and / or provide reliable readings at even lower frequencies. For example, an accelerometer as a motion sensor can provide motion data at a high rate, but may drift over time, for example due to changes in temperature. For example, a tracking sensor as a motion sensor may experience local drift or inaccuracies. Typical inaccuracies may include a (intermittent) lack of motion detection, resulting in erroneous low-speed readings. Similarly, changes in the distance between the surface tracked by the tracking sensor and the sensor may also cause position-related drift. All sensor types may experience short interruptions due to various external factors.

[0025] According to one aspect, potential drift or inaccuracy of a motion sensor may be mitigated by assuming that the position data provided by the position sensor is accurate, and by repeatedly adjusting the dynamic system model based on the position data. Thus, the dynamic system model may include an offset value to be considered in conjunction with the motion data, such that the dynamic system model fits the position of the elevator car as indicated by the position data. The offset value may be determined by treating the position data as absolute position data (i.e., position data indicating the absolute position of the elevator car), and by determining a value by which the motion data needs to be adjusted, such that at the point in time when the position data is provided, the estimated position determined by the dynamic system model corresponds to the absolute position of the elevator car. In a typical case, the offset data may correspond to the drift of the motion sensor, such that the motion data may be used as an input variable to the dynamic system model when the offset is added to or subtracted from a value representing the motion data.

[0026] According to one aspect, the method includes and the estimation unit is configured to determine a sensor reliability parameter based on an offset value. The offset value may indicate a discrepancy between motion data provided by the motion sensor and a state of a dynamic system model. For example, the dynamic system model may be initialized and indicate that the elevator car is static (i.e., not moving), while the motion data provided by the accelerometer, for example due to a failure of the accelerometer, indicates a free fall of the elevator car. In this exemplary case, the input variables based on the motion data will be offset for a larger offset value of the accelerometer to fit the position of the elevator car indicated by the position data, such as an offset corresponding to the earth's gravity. The reliability parameter may be determined based on the offset value by defining a reliability threshold, and if the offset value exceeds the threshold, the reliability parameter may indicate that the motion sensor is unreliable or untrustworthy. Similarly, the reliability parameter may be determined based on the frequency of the offset value adjustment, the rate of change, and / or the sudden change of the offset value. Additionally or alternatively, a reliability index or indicator indicating that the offset value is outside a predefined acceptable level (e.g., exceeding a threshold) may indicate that the sensors providing the input variables for the dynamic system model are inconsistent with each other. A reliability indicator indicating a lack of mutual consistency may be suitable for determining a potentially unsafe condition even if it is not certain whether or which specific sensor is providing erroneous data.

[0027] According to one aspect, in an embodiment with multiple sensors (in particular multiple motion sensors), the reliability parameter may also be determined by comparing the offset value of each sensor.

[0028] According to one aspect, while determining offset values ​​for motion data and / or motion sensors is described, reliability parameters may also be determined for position sensors. Since the offset values ​​are determined so that the dynamic system model fits the position of the elevator car, a failed position sensor may cause the offset values ​​of all motion sensors to be adjusted, and the reliability parameters may indicate that all motion data and / or motion sensors are potentially faulty. Thus, a state in which most or all offset values ​​indicate that the motion sensor is considered unreliable or untrustworthy may correspond to a state in which the position data and / or position sensor is unreliable, and a position sensor reliability parameter may be determined therefrom.

[0029] According to one aspect, a position sensor, in particular a laser distance sensor, may acquire position data at a first frequency. Acquiring position data may include determining sensor readings, optionally processing sensor readings, and / or transmitting position data to an estimation unit based on sensor readings. The first frequency may be low, a low frequency being considered to be a frequency below 100 Hz, below 50 Hz, below 20 Hz, or even below 10 Hz. In some cases, the first frequency may be even lower, for example in some cases the position sensor may only provide position data at random intervals, where there may be a few seconds between each provision of position data. The first frequency may be variable, for example due to limitations of the sensor. For example, according to some embodiments, for certain position sensor types, such as laser distance sensor types that cannot adequately compensate for Doppler shift, it may be beneficial to acquire position data only during slow travel or stationary periods. Therefore, the low frequency may be defined by the travel curve of the elevator car.

[0030] According to one aspect, the motion sensor, in particular an accelerometer or a tracking sensor, may acquire motion data at a second frequency. Acquiring the motion data may include determining a sensor reading, optionally processing the sensor reading, and / or transmitting the motion data to an estimation unit based on the sensor reading. The second frequency may be higher, with high frequencies being considered to be frequencies above 100 Hz, above 200 Hz, above 500 Hz, or even above 1 kHz. The second frequency may be variable, for example due to limitations of the sensor.

[0031] According to one aspect, the security system may be configured for and the method may include: determining the estimated position at a third frequency, the third frequency being higher than the first frequency. According to an embodiment, the third frequency may be any frequency, for example a frequency higher than the first frequency and the second frequency. Therefore, the third frequency may be substantially limited by the computational speed required to provide the estimated position based on the dynamic system model (e.g., the estimation algorithm). According to a preferred embodiment, the dynamic system model may be updated, for example, by performing an update operation of the estimation algorithm based on newly available motion data, and / or updating the dynamic system model at substantially the second frequency or at a frequency between the first frequency and the second frequency. Advantageously, the dynamic system model may be updated when position data or motion data becomes available, and the estimated position may be determined based on the updated dynamic system model. Advantageously, this may provide an accurate estimated position at a sufficiently high frequency (e.g., at substantially the second frequency) while limiting the computational load.

[0032] Advantageously, the methods and systems described herein allow the position, velocity and acceleration of an elevator car to be accurately determined during operation of an elevator installation. Different types of sensors are used, and the technical limitations of each sensor type can be at least partially overcome by generating a dynamic system model that describes the dynamic system, i.e., the movement of the elevator car in the elevator shaft, using position data and motion data. In some embodiments, the safety system can have a safety level. The safety level of the safety system can be higher than the safety level of some or even all of the individual sensors used in the safety system. Advantageously, this can allow, for example, to combine different sensor types according to the requirements of a specific type of elevator installation, thereby increasing flexibility while maintaining high safety standards. Advantageously, sensor reliability parameters are determined, which can be used, for example, to determine potential unsafe conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Reference will now be made in detail to various embodiments, one or more examples of which are shown in the accompanying drawings. In the following description of the drawings, like reference numerals refer to like parts. Generally, only the differences associated with each embodiment are described. Each example is provided as an explanation and is not meant to be limiting. In addition, features shown or described as part of one embodiment may be used on other embodiments or used in conjunction with other embodiments to produce yet another embodiment. This specification is intended to include such modifications and variations.

[0034] Figure 1 shows a schematic elevator installation according to an embodiment;

[0035] Figure 2 shows a schematic diagram depicting the estimation of sensor data; and

[0036] Figure 3 A timeline depicting the estimation of sensor data is shown. DETAILED DESCRIPTION

[0037] Figure 1 An elevator installation 100 is shown with an elevator shaft 110 and an elevator car 120 movably arranged in the elevator shaft 110. The elevator car 120 is suspended on cables driven by a drive system. For the sake of clarity, some components of the elevator installation, such as doors or counterweights, have been omitted from the figure. Other drive systems than cable-based drive systems may be suitable, and the described subject matter is not limited to the types of drive systems shown in the figure.

[0038] The elevator installation 100 comprises a position sensor 140. In the present embodiment, the position sensor 140 is a laser distance sensor configured for emitting a laser beam 144 and receiving a reflection of the laser beam 144 and for determining the distance between the position sensor 140 and a reflector by measuring the travel time of the laser beam 144 between emitting and receiving the laser beam. A reflector 142 is arranged at a reference point at the bottom of the elevator shaft 110, however, according to embodiments, the reflector may be optional, i.e. the reference point may be formed by the surface of the elevator shaft 110. In embodiments with a long elevator shaft, for example in a building with an elevator installation spanning, for example, more than 5 floors, a reflector may be beneficial to improve the signal quality of the reflected laser beam 144.

[0039] like Figure 1 As shown, the position sensor 140 can be mounted at the bottom of the elevator car and emit a laser beam 144 toward the bottom of the elevator shaft, however, other mounting locations (e.g., at the top or side of the elevator car 120) may also be equally suitable. Likewise, the reference point (optionally including the reflector 142) can be set at any location in the elevator shaft, particularly the top of the shaft, adjacent to the highest landing door or the lowest landing door, and / or a wall of the elevator shaft 110 adjacent to or near the top or bottom of the elevator shaft 110.

[0040] like Figure 1 As shown, the elevator facility 100 includes a motion sensor 130, which is a tracking sensor for sensing the speed of the elevator car 120. The motion sensor 130 is mounted on the elevator car 120 and moves with the elevator car. The motion sensor 130 is arranged near a track 132, which is fixedly installed in the elevator shaft 110. The track 132 serves as a reference surface for the motion sensor 130. According to an embodiment, the motion sensor 130 may include a linear optical encoder, and the track 132 may be optically encoded, for example, with a surface pattern (e.g., a surface pattern including incremental lines).

[0041] According to an embodiment, the motion sensor 130 may include a two-dimensional optical tracking sensor suitable for digital image correlation (DIC) and / or optical flow analysis, as described in the general part of the present disclosure. Advantageously, in an embodiment utilizing a two-dimensional tracking sensor, a non-encoded track 132 may be used as a surface to be tracked by the tracking sensor, i.e., tracking may be performed based on changes in the inherent surface texture of the track. Advantageously, the track 132 may be a track of an existing elevator system, such as a guide rail. Advantageously, in place of the track 132, any substantially flat surface of an elevator shaft (e.g., 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 (e.g., a light emitting diode or a laser diode) for illuminating the surface being tracked by the optical tracking sensor.

[0042] like Figure 1 As shown, the elevator installation 100 includes a motion sensor 134. The motion sensor 134 includes an accelerometer. The motion sensor 134 can be installed at any point in or on the elevator car 120, in particular because the accelerometer does not need to interact with a reference point or trackable surface provided in the elevator shaft 110. The accelerometer can be configured to sense the acceleration of the elevator car 120 in the direction of travel (i.e., substantially vertical direction) in the elevator shaft 110. Therefore, the accelerometer can measure the acceleration corresponding to the earth's gravity during stationary or constant motion of the elevator car, and can measure a value that deviates from this acceleration when the elevator car accelerates or decelerates.

[0043] like Figure 1 As shown in FIG. 1 and represented by dashed lines, each of the position sensor 140 and the motion sensors 130, 134 is in communication with an estimation unit 150. The estimation unit 150 is in FIG. Figure 11 is shown as being disposed on the elevator car, however, the estimation unit 150 may also be disposed at a different location, such as within the elevator shaft, within the machine room, or even at a remote location. The estimation unit 150 may include a processor (e.g., a microprocessor, a field programmable gate array, and / or a central processing unit) for executing a software program. The estimation unit 150 may be configured to receive input variables and include a memory for storing the software program and / or input variables, the input variables including position data and motion data as described herein. When executed on the processor, the software program may be configured to generate a dynamic system model of the elevator car 120 moving within the elevator shaft 110, as described herein. When executed on the processor, the software program may include an estimation algorithm as described herein. When executed on the processor, the software program may be configured to perform the method described herein, in particular determining an estimated position of the elevator car, determining an offset value indicating a degree of motion data offset, and determining a sensor reliability parameter based on the offset value. The estimation unit 150 may be configured to receive motion data and position data provided by the position sensor 140 and the motion sensors 130, 134 via a communication connection. Thus, the estimation unit 150 may include one or more interfaces for establishing a communication connection. The estimation unit 150 may also be configured to provide output data, which includes sensor reliability parameters, and optionally provides an estimated position of the elevator car, and / or data derived from the sensor reliability parameters. The output data may also include additional data that can be derived from a dynamic system model, such as data indicating the speed of the elevator car and / or the acceleration of the elevator car. The output data may be provided to other components of the elevator facility, such as a control unit and / or a safety system (not shown) via a communication connection (not shown). The safety system may include the estimation unit 150.

[0044] like Figure 1 As shown, the elevator system 100 has a safety system including a position sensor 140, an estimation unit 150, a motion sensor 130 as a tracking sensor, and a motion sensor 134 as an accelerometer.

[0045] Alternatively, the security system may include a position sensor (e.g., position sensor 140) and a single motion sensor (e.g., motion sensor 130 or motion sensor 134). Likewise, the security system may include a plurality of motion sensors, such as at least two motion sensors, such as motion sensor 130 or motion sensor 134, and the plurality of motion sensors may be of the same type. Figure 2In a beneficial example discussed in further detail, the security system may include two motion sensors 134, such as two independent accelerometers. Likewise, in another example, the security system may include two motion sensors 130, such as two independent tracking sensors.

[0046] like Figure 1 As shown, the components of the security system described herein can be separate components, i.e. can be arranged separately at different locations. Advantageously, in particular the motion sensors 130 and 134 and / or the evaluation unit can be combined in a single physical unit, for example on a single board and / or in a combined housing. Likewise, even the position sensor 140 can also be included in a single unit, for example in a configuration with one or more motion sensors 134. A security system combined into a single unit can advantageously reduce the effort required for installing and / or retrofitting the security system.

[0047] Reference now Figure 2 , a schematic diagram depicting an estimation 200 of sensor data is shown. Figure 2 The estimation 200 described in particular blocks 230a, 230b, 240a, 240b and / or 250a, 250b may be performed by an estimation unit (eg, the estimation unit 150).

[0048] Block 210 represents acquiring position data, such as by a position sensor (e.g., position sensor 140). Blocks 220a and 220b represent acquiring motion data, such as by an independent motion sensor (e.g., two independent motion sensors, such as motion sensor 134). Although this embodiment is described with respect to a motion sensor including an accelerometer that provides motion data indicative of the acceleration of the elevator car, alternative embodiments may include various types of motion sensors and combinations of motion sensors, and be suitable for various types of motion data and combinations of motion data. Likewise, for embodiments having one position sensor and one motion sensor (i.e., embodiments that may utilize a single estimation stream), aspects of the embodiments that are independent of derived information from more than one independent motion data may be implemented similarly.

[0049] like Figure 2 As shown, this embodiment has two independent estimation streams or channels, including blocks 220a-250a and blocks 220b-250b. The position data obtained in block 210 is shared between the two independent estimation streams. In yet another embodiment, estimation 200 may be performed on only one estimation stream, or even on more than two estimation streams, i.e., additional estimation streams may be added. Figure 2 The illustrated estimation flow is substantially identical to the other estimation flows. The estimation flows can be run independently, in particular asynchronously.

[0050] The motion data acquired in blocks 220a, 220b may be transmitted to blocks 230a, 230b via communication connections 222a, 222b. Blocks 230a, 230b may be filter blocks, sensor fusion blocks and / or estimation algorithm blocks. Similarly, the position data acquired in block 210 may be transmitted to blocks 230a, 230b via communication connections 212a, 212b. According to an embodiment, blocks 230a, 230b include a sensor fusion algorithm, in particular a Kalman filter, for generating a dynamic system model of an elevator car 120 moving in an elevator shaft 110. The motion data indicates the motion of the elevator car and may include at least one of an acceleration of the elevator car and / or a velocity of the elevator car. The position data may indicate the position of the elevator car and may include position data as described herein. Thus, in blocks 230a, 230b, a dynamic system model may be initialized to describe the motion of the elevator car based on the motion data and sensor data provided by blocks 210, 220a, and 220b.

[0051] In blocks 230a, 230b, output data is generated based on the initialized dynamic system model. In this embodiment, the output data includes an estimated position of the elevator car and an offset value indicating a degree of deviation of the motion data, as described herein. In addition to or in lieu of the estimated position, the output data may include an estimated velocity of the elevator car, an estimated acceleration of the elevator car, an estimated change in acceleration of the elevator car over time, and / or a confidence indicator, such as an (estimated) error tolerance or an (estimated) standard deviation of each output data.

[0052] Depending on the embodiment, additional input variables may be transmitted to blocks 230a, 230b. For example, additional position data may be obtained from other sensors provided in the elevator installation, such as position data derived from door sensors when the elevator car is stationary at a landing, or when passing a landing door while traveling. Thus, in addition to the position data obtained in block 210, additional position data may be utilized.

[0053] According to an embodiment, the output data can be directly utilized, for example, by a controller (not shown) of an elevator system that is communicatively coupled to one or more of blocks 230a, 230b, to control the operation of the elevator system based on the output data. For example, the estimated position and estimated velocity can be utilized to control an elevator drive to accurately align an elevator car with a landing door.

[0054] According to an embodiment, the estimation 200 may also 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. Figure 2As shown, the output data is transmitted to the safety blocks 240a, 240b via communication connections 232a, 232b. In addition, the position data and motion data obtained by the blocks 210, 220a, 220b can be transmitted to the safety blocks 240a, 240b via communication connections 224a, 224b and 214. Therefore, the safety blocks 240a, 240b can individually estimate data to detect potential unsafe conditions, and further correlate the transmitted data to estimate data to detect potential unsafe conditions. In addition, the estimation results of the independent safety blocks 240a, 240b can be transmitted between the safety blocks 240a, 240b (not shown) and can be compared with the estimation results of the other safety blocks 240c, 240b. This can allow determination of whether the unsafe condition is detected due to the elevator system being in an unsafe condition or due to erroneous sensor readings in other safe conditions.

[0055] According to an embodiment, the safety blocks 240a, 240b may be configured to estimate position data and motion data, in particular by performing a sanity check on the position data and / or motion data acquired in blocks 210, 220a, and 220b. The result of the estimation may be included in the sensor reliability parameter. The motion data and / or sensor data received via the communication connections 224a, 224b, and 214 may be estimated based on the availability frequency of the data. For example, it may be determined whether the sensor providing the data provides the data at an expected frequency. A frequency lower than expected or a lack of data may indicate a sensor failure. Additionally or alternatively, the position data may also be estimated based on unexpected readings. For example, a sudden change or "jump" in position, such as a change in position indicated by the position data exceeding a predefined threshold, may indicate a position sensor failure.

[0056] According to an embodiment, the safety blocks 240a, 240b may be configured to estimate output data, in particular by performing a sanity check on the output data obtained in blocks 230a and 230b and received via communication connections 232a, 232b. A sensor reliability parameter is determined based on the offset value. The reliability of a motion sensor with a high offset value may be considered low, and / or a motion sensor with 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, other parameters (e.g., any data received by the safety blocks 240a, 240b) may be included in the output data of the safety blocks 240a, 240b. In addition, the difference between the data received by the safety blocks 240a, 240b may be determined and the difference may be included in the output data of the safety blocks 240a, 240b.

[0057] like Figure 2 As shown, the output data of the safety blocks 240a, 240b can be transmitted to the control blocks 250a, 250b via the communication connections 242a, 242b. The control blocks 250a, 250b can be included in the safety system. Alternatively, the control blocks 250a, 250b can be arranged in the controller of the elevator facility. The control blocks 250a, 250b can perform certain control operations based on the input data received via the communication connections 242a, 242b, such as recording a sensor reliability alarm or error, reducing the speed of the elevator car to a safe speed, applying the brakes of the facility, stopping the elevator car, placing the elevator facility in a fail-safe state, etc. The control operation can be performed when one or both of the safety blocks 240a, 240b provide a sensor reliability parameter indicating a sensor failure or an unreliable sensor.

[0058] If any of the position, velocity and / or acceleration exceeds a predefined safe value (e.g., exceeds a predefined threshold), further control operations may be performed. For example, the velocity or acceleration of the elevator car may exceed a predefined threshold. For example, the position of the elevator car may be closer to, for example, the top or bottom of the shaft than a position defined as safe or defined as safe at a given speed. Therefore, in addition to the sensor reliability parameters, the output data may also include (estimated) acceleration, (estimated) velocity, (estimated) position and any of the other parameters described herein, and may be estimated by the control blocks 250a, 250b to detect potential unsafe conditions.

[0059] If a difference is detected between the parameters provided to one safety block relative to the other safety block, a control action may be performed. The parameters position, velocity, and / or acceleration may include directly measured values ​​(i.e., sensor data), as well as values ​​estimated based on a dynamic system model and / or estimated by an estimation algorithm of blocks 230a, 230b.

[0060] Advantageously, for example, reference herein Figure 2The described estimation allows for detecting potentially unsafe conditions or component failures, such as sensor failures or sensor unreliability, by analyzing not only the raw sensor data, but also by considering the sensor values ​​in the context of a dynamic system model describing the motion of the elevator car. This can help detect failures that lead to errors. Based on the offset values ​​determined for the motion sensor data, it can be identified whether a motion sensor or position sensor provides unreliable data based on an increase in the offset value required to fit the sensor data to the dynamic system model. Unreliable sensors can be identified even before a complete sensor failure occurs, thereby improving safety and passenger comfort by, for example, allowing a technician to identify and replace one or more unreliable sensors before further potential problems arise.

[0061] Reference now Figure 3 , depicts a timeline 300 describing an estimation of sensor data over a period of time in accordance with an embodiment. Timeline 300 illustrates sequential operations 310a through 310c. As previously described, in a typical embodiment, a dynamic system model may be generated by an estimation algorithm (e.g., a Kalman filter), and the embodiment will be explained with reference to a Kalman filter, however, other estimation and / or sensor fusion algorithms may also be used. As previously described, in a typical embodiment, motion data may be obtained at a higher frequency than position data. In some embodiments, an accurate estimate of the position of an elevator car may be made based solely on motion data over an extended duration (e.g., a few seconds or even minutes). Figure 3 In the illustrated embodiment, the motion data includes acceleration data, however, motion data indicating the speed of the elevator car may be used instead. The operations described with reference to timeline 300 may be implemented in the system, for example, in reference to Figure 1 The security system described is implemented in, and / or used as a reference Figure 2 The method is implemented by using one of the multiple estimation flows described above.

[0062] In operation 310a, based on the availability of motion data indicating the motion (i.e., acceleration) of the elevator car, a Kalman filter is initialized and repeatedly updated. In this case, updating describes an updating step of the Kalman filter, i.e., adjusting the dynamic system model to fit the measured state based on the new motion data. According to this 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 repeatedly determined.

[0063] In operation 330a, position data indicating the absolute position of the elevator car relative to the elevator shaft is available. The position data is used to update the Kalman filter and generate an estimated position based on the position data, and / or both the input variable motion data and the position data.

[0064] Before updating the Kalman filter, a sanity check 320a may be performed. The sanity check may include comparing the estimated position data obtained from the Kalman filter with position data indicating the absolute position of the elevator car. The sanity check may include comparing the estimated position with the absolute position indicated by the position data and checking whether the estimated position is correlated with the absolute position, such as by checking whether the deviation of the estimated position and the absolute position is less than a predefined threshold. For example, if the estimated position deviates from the absolute position, a sensor reliability parameter may be generated indicating a potential failure in one or both of the motion sensor and the position sensor.

[0065] Additionally or alternatively, after the Kalman filter is updated in operation 330a, or after the offset value has been determined as described in operation 340a, a sanity check 322a as described with respect to sanity check 320a may be performed.

[0066] In operation 340a, based on the position data, which is considered to be indicative of an absolute position, the dynamic system model is further updated to fit the absolute position by determining an offset value indicative of a degree of offset of the motion data.

[0067] After the offset value is determined in operation 340a, a sanity check 322a is performed. In addition to the optional operations described for sanity check 320a (which may also be performed for sanity check 322a), it is determined whether the offset value exceeds a threshold, such as a predetermined threshold. In this regard, additionally or alternatively, it may be determined whether a rate of change of the offset value (e.g., as described in the general portion of the present disclosure) exceeds a predetermined threshold. If the threshold is exceeded, a sensor reliability parameter indicating a potential fault in one or both of the motion sensor and the position sensor may be generated. In addition, a failsafe state in which no further estimated position is generated may be entered, and / or the control operations described for control blocks 250a, 250b may be performed.

[0068] If the sanity check 320a, 322a indicates that the estimated position is correlated with the absolute position derived from the position data and the offset value does not exceed the threshold, the security system or method implementing sensor data estimation according to an embodiment can continue to repeatedly perform the operations described herein, i.e., repeatedly estimate the position in operation 310b, as described for operation 310a, and perform operations 320a, 330b, 340b, and 322b as new position data becomes available, as described for operations 320a, 330a, 340a, and 322a. This process can be repeated essentially indefinitely.

[0069] Advantageously, for systems and methods implementing estimation 200, and in particular according to the operations described with reference to timeline 300, estimated position data based on motion sensor data are available at a higher frequency than absolute position data provided by the position sensor. Likewise, safety-related velocity parameters and acceleration parameters may be monitored more reliably based on a combination of the estimated parameters with the sensor reliability parameters.

Claims

1. A method for monitoring an elevator car (120) in an elevator shaft (110), the method comprising: obtaining position data indicating the position of the elevator car (210); acquiring motion data indicative of motion of the elevator car (220a, 220b); determining (230a, 230b) an estimated position of the elevator car according to a dynamic system model, the dynamic system model describing the motion of the elevator car based on input variables, the input variables including the position data and the motion data; Characterized in that the method further comprises: determining an offset value indicative of a degree of deviation of the motion data, wherein the offset value is generated so that the dynamic system model fits the position of the elevator car indicated by the position data; determining a sensor reliability parameter based on the offset value; and Output data including a reliability parameter of the sensor is provided.

2. The method of claim 1, wherein determining the estimated position comprises estimating the position data and the motion data over a period of time using an estimation algorithm, wherein the estimation algorithm comprises a representation of the dynamic system model. The method according to claim 2 , wherein the estimation algorithm comprises a sensor fusion algorithm and / or a Kalman filter.

4. The method according to any one of the preceding claims, wherein acquiring the motion data (220a, 220b) comprises acquiring the motion data with at least two independent sensors.

5. The method according to the preceding claim, further comprising independently estimating the motion data.

6. The method according to any of the preceding claims, wherein the movement data are indicative of at least one of a speed of the elevator car and / or an acceleration of the elevator car.

7. The method according to any of the preceding claims, wherein the position data indicate an absolute position of the elevator car in the elevator shaft.

8. A method according to any one of the preceding claims, wherein The position data indicates an absolute position of the elevator car, the method further comprising: repeatedly determining the estimated position of the elevator car based on the motion data; After acquiring the position data, operations a.) to c.) are performed: a.) adjusting the dynamic system model to fit the absolute position, and determining whether the offset value exceeds a threshold; b.) comparing the estimated position with the absolute position indicated by the position data; and c.) continuing to repeatedly determine the estimated position of the elevator car based on the motion data subject to the following restrictions: - said estimated position is associated with said absolute position derived from said position data, and - the offset value and / or the rate of change of the offset value does not exceed the threshold value.

9. A safety system for monitoring an elevator car in an elevator shaft, comprising: a position sensor (140) configured to acquire position data (210) indicative of a position of the elevator car, a motion sensor (130, 134) configured to acquire motion data (220a, 220b) indicative of motion of the elevator car; An estimation unit (150), the estimation unit being configured to: receiving input variables including the motion data and the position data; determining an estimated position of the elevator car according to a dynamic system model, the dynamic system model describing the motion of the elevator car based on input variables, the input variables including the position data and the motion data; Characterized in that the estimation unit (150) is further configured to: determining an offset value indicative of a degree of deviation of the motion data, wherein the offset value is generated so that the dynamic system model fits the position of the elevator car indicated by the position data; determining a sensor reliability parameter based on the offset value; and Output data including a reliability parameter of the sensor is provided.

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

11. A safety system according to any one of claims 9 to 10, wherein The position sensor (140) is configured to acquire position data at a first frequency, and The motion sensor (130, 134) is configured to acquire motion data at a second frequency, wherein The first frequency is lower than the second frequency, and 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 any one of claims 9 to 11, wherein the position sensor (140) is configured for sensing the distance between the elevator car and a reference point within the elevator shaft.

13. The safety system according to any one of claims 9 to 12, wherein the position sensor (140) comprises a laser distance sensor.

14. The security system according to any one of claims 9 to 13, wherein the motion sensor (130, 134) comprises at least one of the following: an accelerometer for sensing the acceleration of the elevator car, and A tracking sensor is used to sense the speed of the elevator car.

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

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