SENSOR SYSTEM FOR AN ELEVATOR SYSTEM

Description

[0001] The present invention relates to a sensor system for detecting the position of a car of an elevator installation that can be moved along an elevator shaft, to an elevator installation with a sensor system according to the invention, and to a calibration method for a sensor system according to the invention.

[0002] Devices for determining the position of a car in an elevator system are generally known from the prior art. To determine the position of the car, the known devices use a measuring tape laid along the elevator shaft with a position coding that can be read by a sensor unit arranged on the car and movable with the car. The position coding of the measuring tape can comprise permanently magnetized or temporarily magnetized areas, which can be read or scanned by the associated sensor unit using appropriate sensors, such as one or more Hall sensors.

[0003] In this context, EP 3 736 540 A1, for example, discloses a sensor system for detecting the position of a car of an elevator system that can be moved along a shaft. This system comprises a measuring tape made of a ferromagnetic material, magnetic field generating means for temporarily magnetizing the measuring tape in sections, and a sensor unit for detecting changes in a generated temporary magnetic field. The sensor unit, together with the magnetic field generating means, is arranged on the car opposite the stationary measuring tape. The magnetic field generating means generate a temporary magnetic field that also partially penetrates the opposite measuring tape, where it leads to the formation of a magnetic flux that is influenced by the position coding and can be sensed by the sensor unit. The current position of the car can be read from the measuring tape without contact.

[0004] WO 2013 / 057215 A2 discloses a device for detecting the position of an elevator car. The device comprises a sensor unit and an evaluation unit according to the preamble of claim 1.

[0005] EP 3 915 911 A1 describes a system and a method for evaluating the movement of an elevator car within an elevator shaft based on data acquired by means of a rotary encoder or an acceleration sensor.

[0006] WO 2016 / 096823 A1 discloses a device and a test method for testing a transmitter of a first radio communication device or a receiver of a second radio communication device. The first and second radio communication devices share a frequency band but do not use the same communication protocol.

[0007] Such sensor units for an elevator system, which are designed to interact with a corresponding measuring tape, typically comprise at least one, preferably several, Hall sensors for detecting a magnetic field or corresponding magnetic field lines formed at a respective longitudinal position of the measuring tape. The Hall sensors convert a detected magnetic field into an output analog signal, which can then be converted into a position signal for a controller connected to the sensor unit via analog comparators of the sensor unit.

[0008] However, the known sensor systems have increased requirements regarding their signal quality and signal evaluation, resulting in, in particular, a lower reading tolerance and thus increased requirements regarding the precise relative arrangement of the interacting components of the sensor system, in particular the measuring tape and the associated sensor unit. Furthermore, the components used in the sensor system must also have a low tolerance, which further increases the costs of the known sensor systems due to the necessary upstream testing and adjustment processes.

[0009] The present invention is therefore based on the object of addressing and at least partially eliminating the disadvantages known from the prior art. In particular, the object of the present invention is to provide an improved sensor system for position detection, which, in particular, enables optimized signal generation for position detection.

[0010] This object is achieved by the sensor system according to the features of claim 1. Advantageous developments of the invention are described in the subclaims. The present invention also addresses further problems or represents the solution to further objects, as will become apparent from the following description.

[0011] In a first aspect, the present invention relates to a sensor system for detecting the position of a car of an elevator installation that can be moved along an elevator shaft, comprising a measuring tape that can be arranged vertically in the elevator shaft and, in a mounted state, extends along a longitudinal direction, with a position coding formed by a material change, and a sensor unit that can be arranged on the car in the mounted state, which sensor unit is designed to detect on the input side a magnetic field influenced or caused by the position coding, in particular a magnetic stray field, and to generate at least one analog signal therefrom on the output side, wherein the sensor system comprises a converter unit for converting the at least one analog signal into a digital signal and a calibration unit, wherein the calibration unit is designed such thatthat the digital signal can be changed by static calibration and / or dynamic calibration.,

[0012] The measuring tape comprises a position coding, which is particularly formed by a material change encompassed by the measuring tape. The material change can be a permanent magnetization, preferably varying in the longitudinal direction, introduced into a measuring tape base body in the form of north and south poles, which represent a position coding. The position coding generates or causes a respective magnetic field by means of the introduced permanent magnetization, depending on a respective pole introduced at the respective longitudinal position of the measuring tape.

[0013] Alternatively, and particularly preferably, the material change comprises a plurality of recesses introduced into a measuring tape base body made of ferromagnetic material, in particular steel. These recesses preferably vary in the longitudinal direction of the measuring tape and represent a predefined and known position coding. The sensor unit preferably comprises magnetic field generating means for sectionally and temporarily magnetizing the measuring tape, such that a magnetic flux is formed in the measuring tape, preferably along a transverse direction of the measuring tape. The magnetic flux or the magnetic field that is formed in each case is influenced by the material change or the position coding in the measuring tape and leads to the formation of a magnetic stray field that runs outside the measuring tape and can be detected, in particular contactlessly, by the cooperating sensor unit.

[0014] The sensor unit then converts the magnetic field present at the sensor unit's input, in particular the stray magnetic field, into an analog signal that can be tapped at the sensor unit's output. The analog signal preferably represents the respective profile of a detected magnetic field, in particular the stray magnetic field. By evaluating the analog signal, the position coding can be read out and, in particular, an absolute determination of the position of the elevator car within the elevator shaft can be realized.

[0015] According to the invention, the sensor system comprises a converter unit for converting the analog signal into a digital signal. Within the scope of the present invention, the digital signal is formed by a plurality of discrete individual values ​​that represent the temporal profile of the analog signal through discrete individual values. The converter unit is preferably designed as an ADC converter in order to implement the converter unit using a generally proven and thus reliable standard component.

[0016] The calibration unit according to the invention now advantageously enables the sampled digital signal to be changed and thus optimized and / or corrected by a static calibration and / or by a dynamic calibration.

[0017] In the context of the present invention, static calibration is understood to mean a method in which the digital signal is compared with a reference signal of a reference system. A static calibration value, for example, is then determined from the difference between the digital signal and the reference signal. This static calibration value is, in particular, an equivalent value for a positive or negative zero point shift. Additionally or alternatively, it is preferred if the calibration value is implemented by a gain value for a linear, in particular proportional, adjustment of the digital value. Static calibration is preferably carried out only once, in particular during commissioning of an elevator system and / or requires manual activation by a service employee. Further preferably, the sensor unit is not in operative contact with the measuring tape when carrying out static calibration.

[0018] In the context of the present invention, dynamic calibration is understood to mean a method in which individual discrete values ​​of the digital signal are compared with one another in order to determine a dynamic offset value. This dynamic offset value is preferably an equivalent value for a positive or negative zero point shift and / or a gain value for a linear, in particular proportional, adjustment of the digital signal. The dynamic calibration is preferably carried out several times during regular operation of an elevator system. Further preferably, the sensor unit is in operative contact with the measuring tape when carrying out the dynamic calibration in order to thus take all components of the sensor system into account. Preferably, no reference system is required for the dynamic calibration.Rather, measured values, in particular individual values ​​of the digital signal, are evaluated and / or processed on the basis of neighboring and / or past individual values ​​of the digital signal.

[0019] In a preferred embodiment, the calibration unit is configured such that the static calibration comprises determining a static offset value and / or determining a static gain value. Static calibration allows manufacturing-related tolerances of the sensor system to be detected in order to then compensate the digital signal accordingly and to initially detect and then compensate for deviations between the generated digital signal and the reference system.

[0020] This advantageously improves signal quality and makes the sensor system more robust against tolerances of the installed components and / or negative influences, such as temperature drift. Temperature drift is defined as an unwanted temporal change in the physical behavior of the installed components or devices due to the effects of temperature.

[0021] The static offset value is defined as an equal value or offset of the digital signal, resulting in a positive or negative zero point shift of the digital signal. This advantageously compensates for an asymmetry in the magnetic field that can be generated, particularly by the magnetic field generation means. This then advantageously leads to a sensor system that can be designed to be more robust against a displacement of the measuring tape from the centric reference position.Influences that have a negative impact on the signal quality can arise in particular from an unevenly formed magnetic field, in particular in the preferred embodiment of the magnetic field generating means by two permanent magnets that have a different magnetization, and / or an oblique, in particular angular, relative arrangement of the sensor unit to the measuring tape, which can also have an effect due to the formation of an asymmetrical magnetic field, and / or due to age-related wear of a guide rail that is provided for a defined positioning and / or alignment of the measuring tape relative to the sensor unit, wherein the wear is expressed in particular by the measuring tape digging laterally into the guide rail.

[0022] In the context of the present invention, a static gain value is understood to be an amplification, in particular an amplification factor, applied to the discrete individual values ​​of the digital signal. The static gain value results in a magnitude-dependent adjustment of the discrete individual values ​​of the digital signal to compensate for negative influences.

[0023] This advantageously makes the sensor system more robust against play in the measuring tape guidance and / or against vibrations that occur during operation of the elevator car and / or against negative influences of aging processes or temperature drifts of the installed components.

[0024] In other words, deviations in the positioning of the sensor system components, i.e., variations in the relative arrangement of the sensor system components, are also detected in order to compensate for a sensor system individually, i.e., with regard to the tolerance-related properties of the installed components and a realized (real) positioning or relative arrangement of the installed components. This advantageously compensates for manufacturing-related tolerances of the components and / or components installed in the sensor system, in particular those formed by different physical or electrical properties, as well as deviations from a reference position of the components, in order to achieve improved signal quality in the acquisition of measured values.

[0025] Furthermore, within the scope of this preferred embodiment, it is further provided that the static calibration of the sensor system is carried out at a time when the sensor unit is not in operative contact with the measuring tape. The static calibration is thus preferably carried out during assembly and / or commissioning work on the sensor system at a time when the sensor system has already been installed on the elevator car, but is not yet in operative contact with the measuring tape. At this time, the measuring tape is either not yet laid in the elevator shaft or is arranged in an area in the elevator shaft where the measuring tape is not magnetized by the magnetic field generating means.

[0026] In a further development, it is provided that the calibration unit is designed such that the dynamic offset correction comprises determining a dynamic offset value from a previously recorded and stored series of measurements and / or measurement history of past, in particular old, discrete individual values ​​of the digital signal. Preferably, the individual values ​​of the series of measurements represent the temporal progression of the magnetic stray field in a position-dependent manner. Further preferably, the series of measurements comprises individual values ​​that represent the temporal progression during the movement of the elevator car, in particular in certain regions. Preferably, the various regions extend directly adjacent to one another on the measuring tape in the longitudinal direction. Further preferably, two adjacent regions can also overlap in sections in order to thus form a common transition section with respect to the measuring tape.In a transition section, the recorded individual values ​​of the digital signal can thus be contained in the measurement series of a first range and in the measurement series of a second range.

[0027] The generated discrete individual values ​​are preferably stored in a measurement series, with these individual values ​​then being processed to perform the dynamic offset correction. This preferably involves a selection of specific individual values, in particular, first determining the minimum and maximum values ​​of the measurement series, which are then mathematically processed to determine the dynamic offset value. Such mathematical processing may include averaging, in particular a moving average.

[0028] Dynamic calibration is only performed when the measuring tape is in active contact with the sensor unit. Furthermore, dynamic calibration is preferably performed multiple times to compensate for negative influences on the digital signal, particularly those caused by aging. Furthermore, it is preferred that dynamic calibration be based on a digital signal generated from the measuring tape during the elevator car's travel.

[0029] A measurement series formed from discrete individual values ​​of the digital signal can thus consist of individual values ​​of the digital signal, all of which were realized from different longitudinal positions of the measuring tape. In particular, by determining the minimum and maximum values ​​of the digital signal for each region, an average value can be calculated for determining the dynamic offset value. Dynamic compensation thus preferably makes it possible to compensate for the negative influence of a measuring tape that may be laid slightly diagonally in the elevator shaft and / or that varies slightly with regard to correct vertical alignment over its entire length, for example due to building settlement. In a further development, the negative influence of the measuring tape being embedded in a guide rail, in particular made of a plastic material, which is designed to align the measuring tape relative to the sensor unit, can also be reduced.

[0030] Furthermore, it is further provided that the calibration unit is designed such that the measurement series comprises 10, preferably 100, more preferably 1000 individual values ​​of the digital signals.

[0031] Furthermore, the measurement series is preferably based on values ​​generated during elevator car operation. In other words, when generating the individual values, a relative movement between the measuring tape and the sensor unit is preferably present.

[0032] According to a preferred development of the sensor system, the calibration unit is designed such that the dynamic offset correction can be carried out cyclically at static or fixed, in particular specified, or, in particular, definable, variable time intervals. As already mentioned, aging processes that negatively influence the sensor system can thus be detected and compensated accordingly. This advantageously makes the sensor system more robust against disruptive influences, such as a change in the relative arrangement between the measuring tape and the sensor unit. This also advantageously allows the maintenance intervals of the elevator system to be extended, since the negative influence on the sensor system caused by wear can be detected and compensated.

[0033] In a further development, it is also provided that the calibration unit is designed in such a way that the current vertical position of the car in the elevator shaft is taken into account during the dynamic offset correction, i.e. when determining the dynamic offset value.

[0034] In other words, the dynamic offset correction is carried out in a position-dependent manner in order to record a change in the digital signal at a specific longitudinal position of the car in the elevator shaft over the operating time by processing measured values ​​stored for this position from a measurement history.

[0035] According to a further preferred embodiment of the present invention, it is provided that the calibration unit is designed such that the dynamic offset correction is determined and / or calculated in regions with respect to the longitudinal direction of the elevator shaft, wherein a first region is formed directly adjacent to at least one second region in the longitudinal direction or wherein a first region and a second region directly adjacent to the longitudinal direction overlap in sections.

[0036] This allows the calibration unit to advantageously compensate for negative influences caused by an arrangement of the measuring tape in the elevator shaft that is outside a predefined vertical alignment, particularly one that is inclined relative to the vertical alignment. This significantly increases the tolerance of the sensor system with regard to the relative alignment of the sensor unit and the measuring tape, while simultaneously enabling effective position detection.

[0037] In this context, it is further provided that the extension and / or length of the individual predefined regions in the longitudinal direction is selected depending on the magnitude of a potential negative influence. If a first angle, in particular a deviation and / or difference angle, between the longitudinal extension direction of the measuring tape and the vertical axis of a first sensor system is thus smaller than a second angle, in particular a deviation and / or difference angle, between the measuring tape and the vertical axis of a second sensor system, this leads to the regions in the first sensor system being selected to be longer than in the second sensor system. This also leads to an advantageous optimization of the sensor system in order to make it more robust against interference.

[0038] In this context, it is further provided that the calibration unit is designed such that the dynamic offset value for each range of the at least two ranges is determined by a separate moving average of the corresponding digital signals.

[0039] Advantageously, a simple implementation of the dynamic offset correction can be achieved, since the dynamic offset value can be easily determined for the individual areas by means of the moving average calculation.

[0040] Another particularly advantageous feature is the ability to continuously overlay the individual ranges, allowing for position-dependent correction for all positions on the measuring tape using the neighboring discrete values ​​included in the moving average. In addition to moving average calculation, it is also possible to use equivalent mathematical operations to process the multitude of neighboring individual values ​​of the digital signal.

[0041] In a further development, the sensor system comprises an output unit which is designed such that a maintenance signal, in particular for influencing a maintenance interval, can be generated as a result of the dynamic calibration, in particular as a result of the detection of an exceedance or undershoot of a threshold value by the dynamic equivalent value.

[0042] The sensor system advantageously includes communication means for transmitting the maintenance signal to a control center or monitoring service. This can advantageously reduce maintenance costs and increase the operating times of the elevator system, as maintenance can be performed at an optimal time, especially with a delay.

[0043] Furthermore, a further development of the sensor system comprises a sensor unit with at least one Hall element for detecting the magnetic field. By using the Hall element for detecting the magnetic field, a comprehensively tested and cost-effective sensor unit for magnetic field determination can be advantageously used. This advantageously leads to low material costs and reliable operation of the sensor system.

[0044] Within the scope of a further development, it is further provided that the measuring tape is made of a ferromagnetic material, in particular steel, and / or that the magnetic field generating means comprise permanent magnet means or electromagnet means for magnetizing the measuring tape. The measuring tape can advantageously be manufactured from steel at low production costs. Furthermore, steel has a high tensile strength, which is why the use of long steel tapes in tall buildings with correspondingly long elevator shafts is unproblematic due to the robustness of the steel tape. Thus, even if the steel tape is subjected to mechanical stress, there is no immediate risk of the measuring tape tearing. Furthermore, steel has low elongation properties, which has a positive effect on signal detection, in particular on signal quality.

[0045] Furthermore, the present invention also claims protection for an elevator system comprising a car movable between at least two floors in an elevator shaft, as well as a sensor system according to the invention mounted on the car. The measuring tape extends vertically along the elevator shaft, and the sensor unit is arranged on the car in such a way that the sensor unit can interact with the measuring tape for position detection.

[0046] Furthermore, within the scope of the present invention, protection is claimed for a calibration method, wherein the calibration method is provided for a sensor system for detecting the position of a car of an elevator installation that can be moved along an elevator shaft, wherein the sensor system has a measuring tape that can be arranged vertically in the elevator shaft and, in an assembled state, extends along a longitudinal direction, with a position coding formed by a material change, and a sensor unit that can be arranged on the car in the assembled state for interacting with the position coding.

[0047] According to the invention, the calibration method comprises the following method steps: First, magnetic fields influenced or caused by the position coding are detected by the sensor unit and at least one analog signal based thereon is generated. According to the invention, the at least one analog signal is converted into a digital signal by a converter unit. This is followed by the inventive modification of the digital signal by a calibration unit according to the invention in order to perform a static and / or dynamic calibration.

[0048] Advantageously, the present invention significantly improves or optimizes the robustness and tolerance of the sensor system to disturbing influences and at the same time enables effective position detection of the elevator car in the elevator shaft.

[0049] To avoid repetition, features disclosed according to the device should also be considered as disclosed according to the method and should be claimable. Likewise, features disclosed according to the method should also be considered as disclosed according to the device and should be claimable.

[0050] Further advantages, features and details of the invention will become apparent from the following descriptions of preferred embodiments and from the drawings.

[0051] These show in Fig. 1: a schematic side view of a preferred embodiment of an elevator system according to the invention; Fig. 2: a schematic block diagram of a preferred embodiment of the sensor system according to the invention; Fig. 3: a top view of the front of the measuring tape and the corresponding signal waveforms of analog signal U Sense , digital signal Val ADC and compensated digital signal Val ADC_ ; Fig. 4a, b: a schematic representation of the signal quality without and with the calibration unit according to the invention; and in Fig. 5: a cross-sectional view of the measuring tape and associated sensor unit to show the possible displacement in the X and Y directions.

[0052] In Fig. 1 An elevator installation 100 with a sensor system 1 according to the invention is schematically illustrated, which is designed according to a first preferred embodiment of the present invention. The illustrated elevator installation 100 has a car 101 movable in an elevator shaft 102 for transporting people and / or goods between different floors 103a, 103b, 103c, 103d.

[0053] The sensor system 1 according to the invention comprises a sensor unit 4 fixed to the elevator car 101 and a measuring tape 2 fixedly positioned in the elevator shaft 102 in order to read out the current vertical position of the elevator car 101 in the elevator shaft 102 from a position coding 3 formed in the measuring tape 2.

[0054] The measuring tape 2 fixed in the elevator shaft 102 extends in a longitudinal direction L along the vertical elevator shaft 102 and is fixed at a first end to a lower elevator shaft floor and at a second end to an upper elevator shaft ceiling. Each floor 103a-d can thus be assigned a specific longitudinal position on the measuring tape 2. The measuring tape 2 is preferably made of a ferromagnetic material, in particular steel, and comprises a front side 13 aligned with the elevator car 101 with a transverse extension that is formed transversely to the longitudinal direction L. The position coding 3 arranged in the measuring tape 2 is formed by a material change.

[0055] As in Fig. 2 As shown, the sensor unit 4 comprises magnetic field generating means 6, which in the present exemplary embodiment are formed by a first electromagnet 61 and a second electromagnet 62. Alternatively, the magnetic field generating means 6 can comprise correspondingly arranged permanent magnets, in particular bar magnets. In an assembled state, the sensor unit 4 is arranged on the car 101 such that the measuring tape 2 is arranged essentially centrally in plan view to the first electromagnet 61 and the second electromagnet 62. The first electromagnet 61 and the second electromagnet 62 lead to a regional and temporary magnetization of the measuring tape 2 in the respective region of the measuring tape which is arranged between the magnets 61, 62., wherein a magnetic stray field can be generated outside the measuring tape 2 as a function of the position coding 3, which can be detected by the sensor unit 4 and converted into an analog signal 10. The polarity of the opposing magnetic field generating means 6 is preferably opposite. For example, a north pole and a south pole are opposite each other in the transverse direction of the measuring tape.

[0056] Furthermore, the sensor system 1 comprises an output unit 8 configured to generate a maintenance signal to influence a maintenance interval of the elevator installation 100. For this purpose, the output unit 8 comprises communication means 12, which in the present embodiment are configured to establish a wireless communication connection with a central maintenance unit, which is not illustrated in the figure.

[0057] The sensor unit 4 is designed to detect a magnetic field forming on the measuring tape 2, and in particular a magnetic stray field, and generates an analog signal 10 therefrom, which can be tapped at a signal output of the sensor unit 4 and whose profile depicts the temporal profile of the magnetic stray field. For this purpose, the sensor unit 4 preferably comprises at least one sensor element 9, in particular a Hall element, wherein a Hall voltage can be generated from the detected magnetic field, in particular the detected magnetic stray field, which can be tapped as an analog signal 10 on the output side of the Hall element 9.

[0058] Furthermore, the sensor unit 4 comprises a converter unit 5 connected to the sensor element 9, which is designed to convert the analog signal 10, in particular the Hall voltage, into a digital signal 11. In the present embodiment, the converter unit 5 is embodied as an analog-to-digital converter, preferably with a 12-bit resolution. The ADC converter maps the temporal profile of the analog signal 10 using a plurality of individual values ​​that can be generated by periodically sampling the analog signal 10.

[0059] In addition, the sensor unit 4 according to the invention comprises a calibration unit 7 which is set up and / or designed such that the generated digital signal 11 can be changed by a static calibration and / or a dynamic calibration.

[0060] The static calibration comprises determining a static offset value and / or a static gain value and thus advantageously enables compensation for manufacturing-related and / or component-related tolerances of the sensor system 1. These tolerances are caused in particular by the used and / or installed components and / or parts of the sensor system 1 as well as by deviations from a reference positioning of the components and / or parts of the sensor system 1, which result, for example, in a non-ideally central arrangement of the measuring tape 2 in relation to the sensor unit 4.

[0061] The dynamic calibration comprises determining a dynamic offset value which is generated from a series of measurements of previously recorded and stored individual values ​​of the digital signal 11.

[0062] Finally, the sensor system 1 shown also includes a reporting unit 8 having wireless communication means 12. The reporting unit 8 is configured to generate a maintenance signal following the dynamic calibration, i.e., following the exceeding or falling below of a threshold value by the determinable dynamic offset value, which can be transmitted to a central maintenance unit via the communication means 12.

[0063] In Fig. 3 The top view of a front side 13 of a measuring tape 2 known from the prior art is shown, which can be temporarily magnetized between the first electromagnet 61 and the second electromagnet 62 over the entire transverse extent in the respective region located between the magnets 61, 62. Furthermore, the position coding 3 formed in the measuring tape 2 is shown, which is formed by a plurality of, for example, rectangular recesses formed in the measuring tape 2, through which the magnetic flux that can be formed transversely to the longitudinal direction L can be interrupted, which is why the magnetic stray field is formed at the recesses.

[0064] In the figurative representation, the temporal progression of the analog signal 10 detectable from the measuring tape 2 is shown below the measuring tape 2, which signal can be detected by the sensor unit 4 as the measuring tape 2 travels at a constant speed. The schematic signal progression, labeled U Sense on the Y-axis, shows that the analog signal 10 has an approximately sinusoidal progression as the elevator car 101 travels at a constant speed over the respective recesses of the position coding 3, with the peak values ​​of the analog signal 10 being arranged exactly centrally to the material recesses formed in the longitudinal direction L.

[0065] As already explained, the analog signal 10 is converted by the converter unit 5 into a digital signal 11 composed of a plurality of discrete individual values. The sequence of individual values ​​that can be generated from the analog signal 10 and form the digital signal 11 is shown in the diagram below, whose Y-axis is labeled Val ADC.

[0066] The value of the discrete individual values ​​represents the temporal signal curve of the digital signal 11, whereby the voltage range of the analog signal 10 has already been adapted to the 12-bit range of the ADC converter.

[0067] The bottommost signal waveform, whose Y-axis is labeled Val ADC_, represents the signal waveform of the compensated digital signal 11, which can be generated by the calibration unit 7 according to the invention. In the illustrated embodiment, the digital signal 11 is modified by a static calibration such that a zero point shift occurs with respect to the Y-axis. This advantageously allows an asymmetry in the magnetic field generated between the first electromagnet 61 and the second electromagnet 62 to be corrected, which is why an improved signal quality for the digital signal 11 can be achieved.

[0068] The Fig. 4a and 4b show a test result of the achievable signal quality for a sensor system 1 without calibration (cf. Fig. 4a ) and with calibration (cf. Fig. 4b ). During the test, the measuring tape 2 was moved at a speed of 0.02 m / sec, whereby a stepwise variation in the relative arrangement between the measuring tape 2 and the sensor unit 4 was investigated.

[0069] In the tabular representations, the distance a between the front side 13 of the measuring tape 2 and the sensor unit 4 or a sensor element 9 of the sensor unit is shown on the Y-axis (cf. Fig. 5 ), whereby the distance a was increased in 0.2mm steps from 0 to 4mm during the tests.

[0070] The X-axis shows the step-by-step displacement of the measuring tape 2 from a reference position, in which the center of the measuring tape 2 is arranged opposite the center of the sensor unit 4 or the sensor element 9, in a positive direction and an opposite negative direction b (cf. Fig. 5 ). Here, too, measuring tape 2 was moved in 0.2 mm increments, starting from the centric reference position to + / -1.4 mm.

[0071] The generated measured value, i.e. the digital signal 11 before or after compensation, was then compared with a reference system, whereby an assignment to three quality groups was made depending on the deviation between the generated measured value and the reference system.

[0072] The highest quality group is marked in the table by a "1" with a hatching that increases from left to right and a "1" with a hatching that decreases from left to right and indicates that the measured value that can be generated has either a particularly small deviation (for the increasing hatching) or a small deviation (for the decreasing hatching) from the reference system and is therefore fully suitable for further processing.

[0073] In other words, the values ​​marked by a "1" with increasing hatching form a first sub-range of the highest quality group in which there is a particularly small deviation from the reference system, and the values ​​marked by a "1" with decreasing hatching form a second sub-range of the highest quality group in which there is still a small deviation from the reference system.

[0074] A second quality group is marked with a "0", whereby these values ​​already deviate significantly from the reference system, but are still subject to limited further processing.

[0075] A third quality group is marked with a "-", whereby these values ​​deviate so much from the reference system that further processing of the measured values ​​and thus position detection in the sensor system is not possible.

[0076] From the Fig. 4a It can be seen that a larger distance a has only a minor effect on the signal quality when the measuring tape 2 is centrally arranged from the sensor unit 4. However, this is not the case if there is a positive or negative displacement of the measuring tape 2 from the central arrangement along the + / -b direction. Here, the highest quality group drops sharply with increasing distance from the ideal central position; for example, with a displacement of +1.2 mm, the highest quality group can only be achieved at a distance a of 1.6 mm. It should also be noted that the sub-range of the highest quality group, which is indicated by a "1" with increasing hatching, is almost only achievable in the central arrangement.

[0077] In comparison, the signal quality with activated calibration is significantly better, as the highest quality group can be achieved even in the peripheral areas. Advantageously, the highest quality group marked with a "1" can be used instead of Fig. 4a shown schematically pyramid-shaped now band-shaped, whereby the sub-area marked by a "1" with increasing hatching can also be significantly enlarged, especially in the edge areas. For example, with a displacement of +1.2 mm, a particularly small deviation can be achieved within the highest quality group up to a distance a of 3.0 mm (cf. "1" with increasing hatching), whereby the highest quality group can also be realized for values ​​up to 4.4 mm, which is Fig. 4a represents an improvement.

[0078] Advantageously, the elevator system 100 can thus be operated for a longer period of time even in real operation in the event of a wear- or aging-related position shift of the measuring tape 2 from an ideal vertical position or an ideal relative position to the sensor unit 4, since the lateral displacement of the measuring tape 2 from the ideal reference position has a significantly less negative impact on the output signal generation, or at a significantly later time. Thus, the operating times of an elevator system 100 can be increased and maintenance costs reduced.

[0079] The Fig. 5 shows a cross-sectional view of the measuring tape 2 and the sensor unit 4, illustrating the alignment of the distance a and the alignment of the distance b of the measuring tape 2 starting from an ideal centric reference position. In the centric reference position, the center of the measuring tape 2 is arranged opposite the center of the sensor element 9. Bezugszeichenliste

[0080] 1Sensor system 2Measuring tape 3Position coding 4Sensor unit 5Converter unit 6Magnetic field generating means 7Calibration unit 8Output unit 9Sensor element, Hall element 10Analog signal 11Digital signal 12Communication means 13Front of the measuring tape 21First area 22Second area 61first electromagnet 62second electromagnet 100Elevator system 101Car 102Elevator shaft 103a-cFloors LLongitudinal direction QTransverse direction

Claims

1. A sensor system (1) for recording the position of an elevator car (101) of an elevator installation (100) displaceable along an elevator shaft (102), the sensor system (1) comprising a tape measure (2) which is disposable vertically to the elevator car (102), extends along a length (L) in the assembled state and has a position coding (3) formed by a material change and a sensor unit (4) which is disposable on the elevator car (101) and is configured for registering magnetic fields, in particular a stray magnetic field, on the inlet side which are caused or influenced by the position coding (3) and for generating at least one analog signal therefrom on the outlet side, the sensor system (1) comprising a conversion unit (5) for converting the at least one analog signal (10) into a digital signal (11), characterized in that the sensor system comprises a calibration unit (7) which is configured for changing the digital signal (11) by means of a static and / or dynamic calibration.

2. The sensor system according to claim 1, characterized in that the calibration unit (7) is configured such that the static calibration includes determining a static offset value and / or a static gain value for compensating tolerances of the sensor system (1) caused by production.

3. The sensor system according to claim 1 or 2, characterized in that the calibration unit (7) is configured such that the dynamic calibration includes determining a dynamic offset value from a previously recorded and stored measurement series and / or measurement history of past digital signals (11).

4. The sensor system according to claim 3, characterized in that the calibration unit (7) is configured such that the measurement series comprises 10, preferably 100, further preferably 1000, in particular previously recorded and stored digital signals (11).

5. The sensor system according to claim 3 or 4, characterized in that the calibration unit (7) is configured in such a manner that it cyclically executes a dynamic offset correction in set or variable time intervals.

6. The sensor system according to any one of the claims 3 to 5, characterized in that the calibration unit (7) is configured in such a manner that the dynamic offset correction processes a vertical position of the elevator car in the elevator shaft (102) when determining the dynamic offset value.

7. The sensor system according to any one of the claims 3 to 6, characterized in that the calibration unit (7) is configured in such a manner that the dynamic offset correction is computed area by area regarding the length (L) of the elevator shaft (102), a first area (21) along the length being formed directly adjacent to at least one second area (22) or a first area and a second area directly adjacent with respect to length overlapping in areas.

8. The sensor system according to claim 7, characterized in that the calibration unit (7) is configured in such a manner that the dynamic offset value is determined for each area (21, 22) of the at least two areas via an independent sliding averaging of the corresponding digital signals (11).

9. The sensor system according to any one of the preceding claims, characterized in that the sensor system (1) comprises an output unit (8), the output unit (8) being configured in such a manner that a maintenance signal, in particular for influencing a maintenance interval, is generable via the dynamic offset value as a result of recording when a predefined threshold value has been exceeded or fallen below.

10. The sensor system according to any one of the preceding claims, characterized in that the sensor unit (4) has at least one Hall effect element (9), preferably a plurality of Hall effect elements in particular disposed in a row.

11. The sensor system according to any one of the preceding claims, characterized in that the tape measure (2) is made of a ferromagnetic material, in particular steel, and in that the sensor unit (4) has magnetic-field generation means (6) for temporarily magnetizing the tape measure (2), in particular permanent magnet means or electromagnet means (61, 62).

12. An elevator installation (100) comprising an elevator car (101) displaceable between at least two floors (103a-c) in an elevator shaft (102) and a sensor system (1) according to any one of the preceding claims.

13. A calibration method for a sensor system (1) for recording the position of an elevator car (101) of an elevator installation (100) displaceable along an elevator shaft (102), the sensor system (1) having a tape measure (2), which is disposable vertically to the elevator shaft (102), extends along a length (L) and has a position coding (3) formed by a material change, and a sensor unit (4) which is disposable on the elevator car (101) and serves to interact with the position coding (3), the calibration method comprising the following steps: - recording magnetic fields, which are caused or influenced by the position coding (3), by means of the sensor unit (4) and generating at least one analog signal (10) based thereon. characterized by - converting the at least one analog signal (10) into one digital signal (11) by means of a conversion unit (5). - executing a static and / or dynamic calibration by means of a provided calibration unit (7) of the sensor unit (4).