Method for determining occupied state of seat and seat heating device

Abstract

To provide a method for determining an occupied state using seat heating devices arranged in seats, and corresponding seat heating devices allowing the occupied state to be securely and efficiently determined.SOLUTION: The present invention is a method for determining a seat occupied state using seat heating devices provided with heating devices having several heating elements, a first and second terminals and arranged in seats. The method, further, includes applying the AC voltage of a frequency response curve in 10 MHz to 40 MHz or within that partial range on the heating devices to determine the occupied state. Further, a voltage amplitude curve over a whole frequency sweep is determined through two terminals to be compared with a reference curve. The invention, further, relates to the seat heating device performing the method.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a method for determining the occupancy status of a seat by means of a seat heating device provided in the seat, the seat comprising a heating device having several particularly elongated heating elements and a first and a second terminal.

[0002] The invention further relates to a seat heating apparatus having a device for determining the occupancy status of a seat. The seat heating apparatus comprises a heating device, which comprises several particularly elongated heating elements and first and second terminals. Furthermore, an energy supply control device is provided for supplying heating energy to the heating device by passing a heating current. The determining device is set and configured to apply an alternating voltage so as to determine the occupancy status of the seat. [Background technology]

[0003] Above the Tropic of Cancer and below the Tropic of Capricorn respectively, the rail industry faces an increasing demand for cost-optimized operating resources during the cold season. It is therefore not surprising that the search for energy-efficient equipment to maintain a comfortable temperature in passenger trains continues. Currently, heating concepts with distributed heating coils circulated with the air or with central ventilation are commonly used. What both have in common is that the entire interior must be heated, but only local areas where passengers are present.

[0004] The interior is therefore heated by circulating air, which consumes more energy than if seat heating were used.

[0005] Traditionally, the use of seat heating systems has not been economically interesting in the rail industry as it requires additional wiring. Now, wiring harnesses are often available at the seats, especially with USB and mains voltage power supplies for mobile phones, tablets, notebooks etc. used in the seats. As the wiring is already included in the seat, this means that no additional wiring is required in the seat, making seat-based heating concepts both efficient and economically attractive.

[0006] The rail industry, especially in Central Europe, also requires seat occupancy detection. Such data is very important for rail operators. If it is known in real time how many seats are occupied, then the dwell times can be optimized with the right algorithms and, consequently, the passenger flow at each station. Thereby, timetables can be better adhered to and further optimized.

[0007] A typical seat heating device is known, for example, from DE 10 2012 223 342 A1. Summary of the Invention [Problem to be solved by the invention]

[0008] The object underlying the present invention is to provide a method for determining the occupancy situation by means of a seat heating device provided in a seat, and a corresponding seat heating device which allows a reliable and efficient determination of the occupancy situation. [Means for solving the problem]

[0009] According to the invention, this object is achieved by a method having the features of claim 1 and by a seat heating device having the features of claim 13.

[0010] Preferred embodiments of the invention are detailed in the dependent claims, the description and the drawings and their description.

[0011] The method according to the invention is further developed in that to determine the occupancy status, an alternating voltage with a frequency sweep of 10 MHz to 40 MHz or a subrange thereof is applied to the heating device. This is preferably done by two terminals. Furthermore, a voltage amplitude curve over the entire frequency sweep is determined, e.g. recorded, via the two terminals. The determined voltage amplitude curve over the entire frequency sweep is then compared with a reference curve. If the voltage amplitude curve differs from the reference curve by at least 5%, the seat is recognized as occupied.

[0012] The invention is based on several discoveries. Firstly, it was ascertained that the heating device can be used not only for heating the seat, but also, in principle, for detecting the occupancy of the seat. Corresponding developments show that a more accurate and detailed detection can be realized if the heating device is supplied with an alternating voltage which does not necessarily have only one frequency, but also has a frequency sweep. The frequency of the alternating voltage is thus varied during the voltage application. This frequency sweep can be effected in the range between 10 MHz and 40 MHz. It was ascertained that a frequency sweep within this range or a subrange thereof is particularly suitable for determining the occupancy.

[0013] The frequency sweep may be configured, for example, so that the frequency of the AC voltage increases steadily over time over a desired frequency range, although increases and decreases or cyclic progressions may also be provided.

[0014] The presence of a human body on the seat changes the amplitude curve of the voltage that can be measured at the two terminals, as this voltage amplitude curve is essentially affected by the additional body mass, and the water content of that body mass, etc.

[0015] It is desirable to be able to distinguish between occupancy by a person and occupancy by luggage, which is common for example in train compartments. A piece of luggage itself may also have an influence on the AC voltage passed through the heating device of a seat heating system. However, according to the invention it has been found that such influence is relatively small, especially for frequency curves in the range of 10 MHz to 40 MHz, or that there is a detectable difference between a person and luggage, such as a backpack, respectively.

[0016] For a flexible subsequent evaluation, a reference curve of the voltage amplitude curve is preferably recorded and stored, for example in advance, and the voltage amplitude curve determined by the measurement is then compared with the reference curve.

[0017] The invention provides the advantage that influences such as correct wiring or different seat covers can easily be taken into account during the evaluation. Experience has shown that a deviation of at least 5% from the reference curve indicates that the seat is occupied by a person. This deviation can be either an attenuation or a positive change. This deviation can be caused, for example, by couplings, etc.

[0018] It is preferred if the heating device for heating the seat is operated with a heating current, which is different from the alternating voltage for determining the occupancy of the seat. For reasons of efficiency, it is advantageous in both cases if the first and second terminals are used for both energy supplies. In other words, the heating device is either heated by the heating current or a frequency-swept alternating current is applied to determine the occupancy of the seat. Such a design requires as few additional elements as possible compared to conventional seat heating devices, since no additional terminals or the like are required.

[0019] The use of alternating heating currents and alternating voltages for determining occupancy makes it easier to use different frequencies, voltages or currents. This further brings the advantage that the corresponding components only need to be designed for a specific range of applications. For example, very sensitive components can be used to measure voltages that can be damaged if a heating current is applied.

[0020] In principle, several heating devices may be attached to the seat and used for the method according to the invention. However, it is sufficient to provide or even use a single heating device. In contrast to other methods, the method according to the invention requires only one heating device, since no capacitance measurement is performed between two different heating devices. A single heating device, on the one hand, facilitates the basic manufacturing and integration into the seat, and on the other hand, does not increase the wiring effort.

[0021] However, in general, several heating devices can also be used. However, in that case, it is preferred that each heating device is evaluated separately to determine the occupancy of the seat. In other words, the method according to the invention is carried out for each heating device individually and at the end, the results are compared for, for example, three heating devices and, in case of different results, the result of the greater number is taken as the final result.

[0022] In theory, the AC voltage applied to the heating device to determine the occupancy of the seat can be of any type. However, it is advantageous to use a wave-shaped AC voltage. It is therefore preferable to use a square or sinusoidal AC voltage. Experience has shown that a sinusoidal AC voltage has low electromagnetic interactions, so that the determination value is available without large peaks etc.

[0023] The energy of the AC voltage may be relatively low. For example, it is sufficient if the amplitude of the AC voltage is guaranteed to be in the range between 0.05 volts and 12 volts. Experience has shown that a range between 0.5 volts and 12 volts is particularly preferred, since this range ensures that sufficiently high signals can also be evaluated. However, the amplitude range of the AC voltage may also be between 1 volt and 5 volts.

[0024] Generally, various evaluations of the difference between the voltage amplitude curve and the reference curve can be used. It is preferable if this difference is calculated based on the absolute maximum difference at the same frequency, based on several absolute maximum differences at several distinct frequencies, based on an average difference over the frequency curve, based on the area or surface area between the curves, and / or based on a combination of one of the different ones mentioned above. Alternatively or additionally, it has also been found that it may be advantageous to provide the two frequency curves to an AI (artificial intelligence) which performs a corresponding evaluation after a learning process.

[0025] In one application, it is preferred if the reference curve is determined by means of a calibration step, in which an AC voltage with a frequency sweep of 10 MHz to 40 MHz or a subrange thereof is applied to the heating device of an unoccupied seat and the amplitude curve of the voltage is determined as the reference curve via the two terminals. The frequency sweep should be the same one that is subsequently used to determine the occupancy status.

[0026] In this situation, it may be preferable to measure different reference curves in order to gain insight into which frequencies generate particularly good and meaningful signals. For this purpose, tests are carried out to determine a reference curve or frequency curve in which particularly large differences can be measured between occupied and empty seats. It is also possible to carry out several measurements and then average them to calculate a reference curve on which the evaluation is based.

[0027] To determine the occupancy status, only certain frequencies or a very narrow frequency range may be used. In this case, it is advantageous if the heating device is subjected to an AC voltage of a subrange of a frequency sweep from 10 MHz to 40 MHz, in particular of one frequency. Prior to this, the detection frequency or detection frequency range is determined by a detection step, in which an AC voltage is applied to the heating device of the vacant seat with an increasing frequency sweep starting from at least 10 MHz. The value of the amplitude of the voltage between the two terminals is recorded. The frequency sweep of AC voltage is applied to the heating device of the occupied seat, and also the value of the amplitude of the voltage between the two terminals is recorded. Then, a frequency or a frequency range in the frequency sweep, in which the values ​​of the amplitude of the voltage between the vacant seat and the occupied seat have a difference of at least 5%, is selected as the detection frequency.

[0028] This ensures that a frequency range with a particularly high deviation is selected for determining the occupancy situation. As experience shows, certain ranges have higher deviations than others across the frequency range. This depends, for example, on the one hand on the exact design of the heating element and, on the other hand, on its installation and other environmental variables.

[0029] To determine the reference curve, an AC voltage with a frequency curve of 10 MHz to 40 MHz or a subrange thereof is preferably applied to the heating device of the vacant seat, and a voltage amplitude curve is determined over the entire frequency curve via two terminals. The voltage amplitude curve is then defined and stored as a reference curve, and the reference curve can be used to evaluate the occupancy situation.

[0030] It has been shown that in principle it is possible to determine or define a reference curve before commissioning and apply it to various embodiments and installations. However, it is preferable and more accurate to determine such a reference curve separately for each heating device or seat heating arrangement in the installed state. For example, if such seat heating arrangements are used in trains, it may be preferable to do this periodically, when the train is in the depot, especially at night, to ensure that no one is sitting in the seat. This further makes it possible to take into account signs such as aging.

[0031] Furthermore, an AC voltage of a frequency curve between 10 MHz and 40 MHz or a subrange thereof may be periodically applied to the seat, and the voltage amplitude curve may be determined and stored via the two terminals throughout the frequency sweep. Furthermore, the current voltage amplitude curve is compared with the preceding voltage amplitude curve as a reference curve. In this way, the occupancy of the seat may be determined at predetermined intervals. A check may be made when the seat heating is activated to prevent unnecessary heating.

[0032] An advantage of the present invention is that it can be used with heating devices having heating elements connected in series or parallel with one another, as well as combinations thereof, which is often stringent, especially with other seat occupancy devices based on capacitance technology.

[0033] In principle, the heating elements of the heating device can be made of any material. Heating threads, heating strands, heating wires, heating bulbs, wrapping threads, current conductors embroidered on woven (flat) fabrics and / or current conductors printed on (flat) fabrics are particularly suitable for this purpose. In general, combinations of these are also possible and can be used.

[0034] The seat heating device according to the present invention is further developed in that the determining device is configured and set to apply an alternating voltage with a frequency sweep of 10 MHz to 40 MHz or a sub-range thereof. The determining device comprises a sensor device, which is configured and set to determine a voltage amplitude curve over a reference sweep via two terminals. The determining device is further configured and set to compare the determined voltage amplitude curve with a reference curve and determine the seat as occupied if the determined voltage amplitude curve deviates from the reference curve by at least 5%.

[0035] In other words, the seating device may be configured with corresponding detection devices and sensor devices to carry out the method according to the invention. Here, it is preferred if the energy supply control device is configured and set to supply the heating device with either a heating current or an alternating voltage for determining the occupancy situation. This brings the advantage that the sensor device can be configured, for example, to be more sensitive or less robust. The sensor device may be designed with components that are generally not suitable for higher energy heating currents, but allow for high-precision measurement of the alternating voltage or its amplitude curve.

[0036] In principle, the frequency curve could also go from high frequencies towards low frequencies.

[0037] The seat heating device according to the invention can preferably be used in vehicles, for example trains, in particular passenger cars. However, it may also be used in the medical field or in nursing homes to determine the occupancy of a bed. Alternatively, such a seat heating device can also be used to determine the occupancy of a waiting room or, in principle, the occupancy of a seat.

[0038] The invention is explained in more detail below by means of schematic exemplary embodiments with reference to the drawings, in which: [Brief description of the drawings]

[0039] [Figure 1] FIG. 1 is a diagram of two seats for which occupancy is to be determined. [Diagram 2] FIG. 2 is a schematic diagram of a heating device. [Diagram 3] FIG. 1 is a highly simplified function-based diagram of a seat heating device according to the present invention. [Figure 4] FIG. 13 is a diagram of voltage amplitude curves at different frequencies for an occupied seat and an empty seat. [Diagram 5] FIG. 5 is a diagram of the difference between the two amplitude curves of FIG. 4 across the frequency curve. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0040] Figure 1 shows a schematic view of two seats 5. The seats comprise a seat surface, a back surface and a head support. A seat heating device 10 according to the invention is shown in the seat surface. In principle, a seat heating device may additionally or alternatively be integrated in the back area. However, for the purposes of the invention, it is sufficient to provide a single seat heating device 10.

[0041] 2 shows a schematic diagram of the internal structure of a heating device 20 of a seat heating apparatus 10 according to the present invention. The heating device 20 comprises first and second terminals 21, 22. Corresponding heating elements 25 extend from these terminals and may be connected in series, parallel or a combination thereof. By passing an electric current through the terminals 21, 22, the heating elements 25 heat up and transfer the heat to the surrounding material. Heating is usually achieved by resistive losses of the electric current.

[0042] The heating element 25 can be made, for example, from special heating threads, heating strands, heating wires, heating twisted yarns, wrapping yarns or even current conductors embroidered on a woven (flat) fabric or a woven surface item. The heating element can also be designed as a current conductor printed on a woven fabric. In principle, a combination of the various designs is also possible.

[0043] 3 is a highly simplified, function-based diagram of a seat heating apparatus 10 according to the invention, which comprises a heating device 20 including two terminals 21, 22. For operation as a seat heating apparatus 10, the two terminals 21, 22 are connected to a power supply control device 30. During operation, a current flows through the heating device 20 via the power supply control device 30, which causes the heating element 25 to heat up and the heating device 20 to warm up. For this purpose, both direct and modulated currents can be applied.

[0044] According to the invention there is further provided a decision making device 40 comprising a sensor device 41. The sensor device 41 does not necessarily have to be part of the decision making device 40 but may only be logically associated thereto. It is essential for the invention that the decision making device 40 and the sensor device 41 interact in order to carry out the method according to the invention.

[0045] In principle, it is only necessary that the heating device 20 is mounted in the seat 5, while the other elements may be arranged outside the seat 5 with suitable wiring in some connection manner.

[0046] To determine the seat occupancy by using the method according to the invention, this determination is initiated, for example, by the power supply control device 30. However, this determination may also be performed by a separate higher-level device. First, it is checked that the power supply control device 30 does not supply power to the heating device 20. This check can be performed, for example, by means of an indicator switch. Then, the determination device 40 applies an alternating voltage, for example a sinusoidal voltage, to the two terminals 21, 22 of the heating device 20. At the same time, the amplitude curve of the voltage is recorded by the sensor device 41, preferably via the two terminals 21, 22.

[0047] For example, the AC voltage may have a frequency sweep from 10 MHz to 40 MHz. The determination device 40 then compares the amplitude curve of the measured voltage with a reference curve and, if a deviation of more than 5% is detected, then determines that the seat 5 is occupied.

[0048] For clarity, in the following reference is made to figures 4 and 5. Figure 4 shows an example of two voltage amplitude curves over the frequency range from a few MHz to 40 MHz. In this figure, one is a voltage reference curve 50 and the other is a measured voltage curve 51 of an occupied seat. As can be seen in the figure, the two curves are very different.

[0049] Depending on the exact design of the heating device 20, the cable connections used and also the person sitting in the seat 5, the amplitude curves of the reference voltage and the measured voltage will be more or less clearly different.

[0050] In Fig. 5 only the difference 52 between the reference amplitude curve 50 and the amplitude curve 51 shown in Fig. 4 is shown. As can be seen, a particularly clear difference occurs in the range between 30 MHz and 40 MHz. It may therefore be preferable to consider only a certain frequency range in the frequency sweep. It is also possible to specify only a single frequency.

[0051] Various methods can be used to evaluate the difference between the determined amplitude curve 51 and the reference curve 50. Figure 5 shows the absolute difference 52 between the two curves. However, for example, the surface area of ​​the difference may also be analyzed. Likewise, the maximum difference, or the difference at a particular frequency, may be considered. It is therefore also possible to combine different evaluations.

[0052] Various methods can be used to determine the reference curve 50. On the one hand, a corresponding measurement can be carried out once after installation of the seat heating device 10 according to the invention and the voltage curve can be stored as a reference curve. However, it is also possible to re-determine the reference curve several times a day, for example to take into account deviations due to temperature fluctuations or ageing. Ideally, this should be done when the occupancy of the seat is known.

[0053] The method according to the invention and the seat heating device according to the invention make it possible to determine the occupancy status of a seat simply and efficiently.

Claims

1. 1. A method for determining the occupancy status of a seat using a seat heating device provided in said seat, the seat heating device comprising a heating device having a plurality of, in particular, elongated heating elements and a first and a second terminal, the method comprising the steps of: applying an alternating voltage having a frequency sweep of 10 MHz to 40 MHz or any subrange thereof to the heating device to determine the occupancy status; a voltage amplitude curve is determined across the frequency sweep via the two terminals; The voltage amplitude curve is compared to a reference curve; If the voltage amplitude curve differs from the reference curve by at least 5%, the seat is recognized as occupied. method.

2. the heating device for heating the seat is operated with a heating current, the heating current is different from the AC voltage for determining the occupancy state; In either case, the first and second terminals are used. The method of claim 1.

3. A single heating device is used, The method of claim 1.

4. a plurality of heating devices are used, each heating device being evaluated separately to determine the occupancy status of the seat; The method of claim 1.

5. The alternating voltage used is of a wave shape, in particular a square or sinusoidal wave shape, The method of claim 1.

6. The amplitude of the AC voltage is selected within the range between 0.05 V and 12 V. The method of claim 1.

7. The difference between the voltage amplitude curve and the reference curve is calculated based on an absolute maximum difference at the same frequency, multiple absolute maximum differences at multiple distinct frequencies, an average difference over a frequency sweep, a surface area between the curves, and / or different combinations thereof; The method of claim 1.

8. The reference curve is determined using a calibration step, in which an AC voltage with a frequency sweep of 10 MHz to 40 MHz or a subrange thereof is applied to the heating device of an empty seat, and an amplitude curve of the voltage is determined as the reference curve via the two terminals. The method of claim 1.

9. If an AC voltage of a sub-range of the frequency sweep from 10 MHz to 40 MHz, in particular a frequency, is applied to the heating device to determine the occupancy status, a determination frequency is determined using a determination step, in which AC voltages of increasing frequencies of a frequency sweep starting from at least 10 MHz are applied to the heating device of an unoccupied seat and values ​​of the amplitude of the voltage via the two terminals are recorded, and AC voltages of the frequency sweep are applied to the heating device of an occupied seat and values ​​of the amplitude of the voltage via the two terminals are recorded, the determination frequency is selected from among the frequencies of the frequency sweep, at which the values ​​of the amplitude of the voltage between the unoccupied seat and the occupied seat have a difference of at least 5%.

9. The method according to any one of claims 1 to 8.

10. the alternating voltage is applied to the heating device of an empty seat at a frequency sweep of 10 MHz to 40 MHz or a subrange thereof to determine the reference curve; a voltage amplitude curve is determined across the two terminals over the frequency sweep; The voltage amplitude curve is defined as the reference curve.

9. The method according to any one of claims 1 to 8.

11. the alternating voltage is periodically applied to the seat at a frequency sweep of 10 MHz to 40 MHz or any subrange thereof; a curve of the amplitude of the voltage across the two terminals is determined and stored over the frequency sweep; The current voltage amplitude curve is compared with a previous voltage amplitude curve as a reference curve.

9. The method according to any one of claims 1 to 8.

12. the plurality of heating elements are selected from heating threads, heating strands, heating wires, heating sewing threads, wrapping threads, current conductors embroidered on a textile substrate, and / or current conductors printed on a textile substrate; 9. The method according to any one of claims 1 to 8.

13. 1. A seat heating apparatus comprising a determining device for determining an occupancy status of a seat, the determining device comprising: a heating device having several particularly elongated heating elements and first and second terminals; a power supply control device for supplying heating energy to the heating device by applying a heating current; having the determination device is constructed and set to apply an alternating voltage to detect the occupancy status of the seat; the determining device is constructed and arranged to apply the alternating voltage at a frequency sweep of 10 MHz to 40 MHz or any subrange thereof; the determining device comprises a sensor device constructed and arranged to determine an amplitude curve of the voltage across the frequency sweep via the two terminals; the determining device is configured and set to compare the determined voltage amplitude curve with a reference curve and determine that the seat is occupied if the determined voltage amplitude curve deviates from the reference curve by at least 5%. Seat heating system.

14. the power supply control device is configured and set to supply to the heating device either the heating current or the AC voltage for determining the occupancy status; 14. A seat heating device according to claim 13.

15. A seat heating device according to claim 13 or 14, Vehicles, especially trains.

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