Seat occupancy sensor and method for determining seat occupancy

Abstract

The present disclosure relates to a seat occupancy sensor assembly comprising: at least a first radar sensor having a first radar lobe for detection of physical presence at a first seat in a first direction; at least one wireless transceiver for wireless communication with an external unit; at least one power supply for powering the seat occupancy sensor; processing circuitry configured to activate the first radar sensor to emit first radar signals in the first radar lobe, and to receive and analyze reflected radar signals to determine seat occupancy for the first seat; one or more absorbing structures, wherein the one or more absorbing structures are made of, or lined with, a material capable of absorbing emitted radar signals to limit the first radar sensor to emit the first radar signals in a desired direction in the first radar lobe; and a housing enclosing the first radar sensor, the at least one wireless transceiver, the at least one power supply, the processing circuitry, and the one or more absorbing structures. The disclosure further relates to a method for determining seat occupancy.

Description

[0001] P7318PC00

[0002] 1

[0003] Seat occupancy sensor and method for determining seat occupancy

[0004] The present disclosure relates to a seat occupancy sensor assembly, which uses radar sensor technology, for determining seat occupancy in, e.g. a train carriage. The disclosure further relates to a method for determining seat occupancy.

[0005] Background

[0006] The use of seat occupancy sensors in passenger vehicles, such as trains, has gained significant interest due to their potential to optimize seat utilization and operational efficiency. Traditional seat occupancy detection methods often rely on pressure sensors, infrared sensors, or camera-based solutions. These systems attempt to identify whether a seat is occupied by measuring pressure changes, heat signatures, or by visual analysis. However, such approaches have shown limitations in terms of reliability and accuracy, especially in dynamic environments like trains where passengers frequently move, change positions, or leave items behind on seats. Additionally, cameras in trains can be prone to vandalism or tampering by passengers, resulting in damaged or disabled sensors and increased maintenance costs.

[0007] One disadvantage of the existing seat occupancy sensors is their inability to consistently distinguish between a person occupying the seat and other inanimate objects, such as bags, coats, or other items left on the seat. Pressure-based sensors, for instance, can be triggered by heavy objects, leading to false positive results, while camera-based solutions may face privacy concerns or may not function well under poor lighting conditions, and can be prone to vandalism.

[0008] Another issue is that the accuracy of these sensors is often affected by variations in passenger sizes, weights, and postures. For example, the detection of a child, who may occupy a smaller surface area, differs significantly from the detection of an adult. Similarly, passengers who slouch or change their seating position may confuse the sensor, leading to inconsistent results. Consequently, the current state of the art has been unable to provide a reliable and robust solution for seat occupancy detection in real-world conditions, impacting operational decision-making and customer satisfaction.

[0009] Given these limitations, there is a need for robust a seat occupancy sensor system that not only provides accurate detection but is also capable of distinguishing between P7318PC00

[0010] 2 humans and inanimate objects in a variety of seating conditions. Such a system should be able to handle diverse passenger profiles, minimize false positives and negatives, and function reliably even in complex environments with high variability in seating arrangements.

[0011] It is therefore an objective of the present disclosure to provide a seat occupancy sensor system and method that overcomes one or more of these challenges.

[0012] Summary

[0013] The present disclosure relates to a seat occupancy sensor assembly comprising: a first radar sensor having a first radar lobe for detection of physical presence at a first seat in a first direction; at least one wireless transceiver for wireless communication with an external unit; at least one power supply for powering the seat occupancy sensor; and processing circuitry configured to activate the first radar sensor to emit first radar signals in the first radar lobe and to receive and analyze reflected first radar signals to determine seat occupancy for the first seats; one or more absorbing structures, wherein the one or more absorbing structures are made of, or lined with, a material capable of absorbing emitted radar signals to limit the first radar sensor to emit the first radar signals in a desired direction; and a housing enclosing the first radar sensor, the at least one wireless transceiver, the at least one power supply, the processing circuitry, and the one or more absorbing structures. The absorbing material may be configured to ensure that the radar sensor emits radar signals only in the desired direction within the radar lobe. By absorbing energy radiated outside this direction, the material effectively prevents the emission of side lobes or stray radiation that could otherwise illuminate unwanted areas of the vehicle interior.

[0014] Radar technology offers several advantages for seat occupancy detection compared to traditional methods, such as pressure sensors or camera-based systems. By using radar, the assembly can reliably detect seat occupancy without requiring physical contact, making it unaffected by minor vibrations or variations in passenger seating positions. Furthermore, radar-based systems are less susceptible to environmental factors such as lighting conditions, which can impede the performance of camerabased solutions, and do not raise privacy concerns since they do not capture visual data. The high resolution and sensitivity of millimeter-wave radar provide precise measurements of the presence and movements of seated passengers, enabling the P7318PC00

[0015] 3 system to distinguish between a human occupant and inanimate objects placed on the seat.

[0016] In one embodiment, the seat occupancy sensor assembly may be provided as an independent unit enclosed within a housing. The housing may contain the first radar sensor, the wireless transceiver, the power supply, the processing circuitry, and the absorbing structures. By integrating all components into a single enclosure, the assembly may form a self-contained module that can be mounted in a vehicle, such as a train, as one complete unit, for example under or in a roof console or luggage shelf. This configuration allows the assembly to be retrofitted into existing vehicles without major modifications to the vehicle structure or wiring. The housing may also ensure that the radar sensors and the absorbing structures maintain a fixed spatial relationship, improving calibration stability and simplifying installation.

[0017] In one embodiment, the seat occupancy sensor assembly may further include one or more shielding structures made of a reflecting material. These shielding structures can be arranged to limit the emission of radar signals to the desired detection area, thereby reducing interference from surrounding seats or surfaces. Such shielding may also be used to focus the radar lobes more precisely on the seats, enhancing detection accuracy by minimizing signal scattering from other parts of the vehicle.

[0018] The absorbing structures may be be made of or lined with materials capable of absorbing emitted radar signals and / or reflected signals outside the designated radar lobes. The term “absorbing” in this context refers to RF absorbing, i.e. a material that can absorb unwanted electromagnetic waves. This can be achieved by making sure that radar signals are only emitted in the desired direction. This feature thus helps prevent unwanted reflections from the surrounding environment and ensures that only signals originating from the seats of interest are processed, further reducing the likelihood of false detections caused by external reflections.

[0019] Additionally, the seat occupancy sensor assembly may further comprise one or more lenses for forming and directing the emitted radar signals within each radar lobe. These lenses can be specifically shaped to optimize the coverage of the seats and ensure that the detection zones are confined to the areas where occupancy needs to be monitored. P7318PC00

[0020] 4

[0021] In one embodiment there are at least two radar sensors. The seat occupancy sensor assembly may further comprise a second radar sensor having a second radar lobe for detection of physical presence at a second seat in a second direction

[0022] In some embodiments, the seat occupancy sensor assembly may comprise a single radar sensor configured to monitor one seat position. In other embodiment, there are at least two radar sensors. The seat occupancy sensor assembly may further comprise a second radar sensor having a second radar lobe for detection of physical presence at a second seat in a second direction. The principles and configurations described for the first radar sensor may, where appropriate, be applied correspondingly to the second radar sensor or to any additional radar sensors that may be included. Similarly, where features or functions are described in connection with two or more radar sensors (first and second radar sensors, first and second radar lobes, first and second directions, first and second seats etc.), these may also be applicable to embodiments comprising only one radar sensor. Conversely, embodiments described with reference to a single radar sensor may, in general, be extended to configurations employing multiple radar sensors operating in parallel or in cooperation. The number of radar sensors included in the assembly may thus be selected according to the desired seat coverage, installation space, or system requirements, without departing from the scope of the disclosure.

[0023] The configuration with two radar sensors in a single assembly enables effective monitoring of two adjacent seats, a common arrangement in train carriages. This design reduces the number of sensor units needed, lowering overall installation costs and simplifying system deployment. By having each radar lobe specifically aligned with its designated seat, the system ensures that the detection area precisely matches the seat layout, minimizing interference and improving accuracy. This dual-seat coverage allows one sensor to detect occupancy at one seat while the second radar sensor monitors the neighboring seat. In principle it is also possible to have by a seat occupancy sensor assembly having only one radar sensor.

[0024] The disclosure further relates to a method for determining seat occupancy, the method comprising the steps of providing a seat occupancy sensor comprising at least a first radar sensor having a first radar lobe for detection of physical presence at a first seat in a first direction; and one or more absorbing structures made of, or lined with, a material capable of absorbing emitted radar signals to limit the first radar sensor to emit the first P7318PC00

[0025] 5 radar signals in a desired direction in the first radar lobe; activating the first radar sensor to emit first radar signals in the first radar lobe towards the first seat;; directing the emitted radar signals using the one or more absorbing structures such that radar energy deviating from desired directions is absorbed; receiving and analyzing reflected first radar signals from the first radar lobe to determine seat occupancy for the first seat. The seat occupancy sensor assembly may comprise a second radar sensor having a second radar lobe for detection of physical presence at a second seat in a second direction. The one or more absorbing structures may be configured to limit the second radar sensor to emit the second radar signals in a desired direction in the second radar lobe. The method may further comprise the steps of activating the second radar sensor to emit second radar signals in the second radar lobe towards the second seat; and receiving and analyzing reflected second radar signals from the second radar lobe to determine seat occupancy for the second seat.

[0026] This method enables detection of seat occupancy for multiple seats using a single sensor assembly, ensuring a high level of accuracy even in dynamic seating environments where passengers may frequently change positions. By analyzing reflected signals for each seat independently, the method can efficiently distinguish between actual seat occupancy and temporary placements of objects, resulting in robust and reliable detection under various seating conditions.

[0027] Description of drawings

[0028] Various embodiments are described hereinafter with reference to the drawings. The drawings are examples of embodiments and are intended to illustrate some of the features of the presently disclosed seat occupancy sensor and method method for determining seat occupancy, and are not to be construed as limiting to the presently disclosed invention.

[0029] Fig. 1 shows an exploded view of one embodiment of the presently disclosed seat occupancy sensor.

[0030] Figs. 2A-B show two cross-sections of one embodiment of the presently disclosed seat occupancy sensor.

[0031] Fig. 3 shows a perspective view of one embodiment of the presently disclosed seat occupancy sensor.

[0032] Fig. 4 shows an example of a flow chart of the presently disclosed method for determining seat occupancy. P7318PC00

[0033] 6

[0034] Detailed description

[0035] The present disclosure relates to a seat occupancy sensor assembly comprising: a first radar sensor having a first radar lobe for detection of physical presence at a first seat in a first direction; at least one wireless transceiver for wireless communication with an external unit; at least one power supply for powering the seat occupancy sensor; and processing circuitry configured to activate the first radar sensor to emit first radar signals in the first radar lobe and to receive and analyze reflected first radar signals to determine seat occupancy for the first seat.

[0036] The seat occupancy sensor assembly may further comprise a second radar sensor having a second radar lobe for detection of physical presence at a second seat in a second direction. The processing circuitry may be further configured to activate the second radar sensor to emit second radar signals in the second radar lobe and to receive and analyze reflected second radar signals to determine seat occupancy for the second seat.

[0037] The embodiments and features described in the present disclosure may be used by a seat occupancy sensor assembly having one radar sensor and a seat occupancy sensor assembly having two or more radar sensors. Accordingly, for example, any processing feature that is described in a way that can be applied to an embodiment having one radar sensor shall be construed as being possible to use in a seat occupancy sensor assembly having one radar sensor or a seat occupancy sensor assembly having two or more radar sensors.

[0038] Throughout the present disclosure, the term “radar sensor” should be understood as a device that comprises both a radar transmitter and a radar receiver. The radar transmitter is configured to emit radar signals, while the radar receiver is configured to detect and analyze the signals reflected back from objects within the detection area. The radar sensor may operate in various frequency bands, including but not limited to the millimeter-wave band, to provide high-resolution detection of seat occupancy. The transmitter and receiver components of each radar sensor can be integrated into a single unit or implemented as separate elements within the sensor assembly, depending on the specific configuration. The emitted radar signals may be modulated using various techniques to enable precise measurement of distance, speed, and movement of objects. The receiver, in turn, captures the reflected signals and P7318PC00

[0039] 7 processes them to extract relevant data, such as amplitude, phase shifts, and time-of- flight information, which are used to determine the presence and characteristics of an occupant. In some embodiments, the radar sensor may include additional components, such as multiple antennas for directing the radar signals, lenses for shaping the emitted beam, and signal processors for pre-processing and / or post-processing the radar data. Thus, the term “radar sensor” is to be construed broadly as a multi-functional unit capable of both signal transmission and reception, and it may include various supporting elements to optimize its performance in different detection scenarios.

[0040] In one embodiment of the present disclosure, the seat occupancy sensor may further comprise a first lens for forming and / or directing the first radar signals in the first direction and / or a second lens for forming and / or directing the second radar signals in the second direction. A lens, in this context, refers to a component that shapes the emitted radar signals to ensure the desired coverage area is achieved. This shaping can involve focusing the radar beam, adjusting its width, or modifying its angular spread to match the seat layout. The lenses can be, but are not necessarily made from dielectric materials such as polymers that are transparent to radar frequencies, allowing the radar waves to pass through with minimal loss. As would be realized by a person skilled in the art, the lenses may be made from any suitable material.

[0041] In some embodiments, one or more lenses may be integrated into the housing of the seat occupancy sensor, for example as a molded or insert-mounted part of the housing wall through which the radar signals are transmitted. This arrangement may simplify assembly and ensure stable alignment between the lens and the radar sensor. In other embodiments, the lens may be provided as a separate optical element placed in front of the radar antenna or integrated directly into the radar chip package itself, forming a compact on-chip lens structure. These alternatives may allow flexibility in design and manufacturing, depending on the desired beam shape, installation constraints, and cost considerations.

[0042] The specific design of the lenses may vary depending on the intended use case. For instance, a plano-convex lens may be used to narrow the radar lobe for seats that are closely positioned, while a concave lens may be used to widen the lobe for more extensive seat coverage. Alternatively, an aspheric lens may be used to correct spherical aberrations, providing a more uniform radar beam profile. In one embodiment the first lens and / or the second lens is shaped as a step cone. The integration of these P7318PC00

[0043] 8 lenses allows the radar sensors to detect occupancy more accurately by minimizing signal spillover to adjacent seats. This configuration may be useful in high-density seating environments, such as train carriages or airplanes, where precise seat-by-seat detection is necessary.

[0044] In one embodiment of the present disclosure, the seat occupancy sensor may further comprise one or more shielding structures made of a reflecting material arranged to limit the first radar sensor to emit the first radar signals in the first radar lobe and to limit the second radar sensor to emit the second radar signals in the second radar lobe. A shielding structure in this context refers to a component or material, often metallic, that reflects or blocks radar signals. These structures can be used to confine the radar beams to the desired areas, preventing them from spreading into adjacent seats or reflecting off unwanted surfaces.

[0045] The shielding may, as an example, be implemented as a metallic plate surrounding the radar sensors or as internal reflective surfaces within the sensor housing. Different shapes and configurations of shielding can be used depending on the seating environment. For example, a parabolic-shaped shield may be used to direct the radar signals more precisely toward a seat, while flat reflective plates can be used to block signals from spreading into unintended areas. The shielding structures may also include multi-layered materials with alternating reflective and absorbing layers, which can enhance the directional properties of the radar lobes.

[0046] In one variation, the shielding structures may be configured to adjust the radar lobe shape dynamically. For instance, the system may include movable or adjustable shields that can change position based on real-time conditions, such as the presence of obstructions or changes in seating layout. This flexibility can improve the robustness of the sensor in environments where the seating configuration may vary or where passengers frequently move around.

[0047] In one embodiment of the present disclosure, the seat occupancy sensor may further comprise one or more absorbing structures, wherein the absorbing structures are made of or lined with a material capable of absorbing emitted radar signals and / or reflected radar signals. An absorbing structure, in this context, is designed to prevent that that radar signals are emitted outside the desired direction. P7318PC00

[0048] 9

[0049] The absorbing structures may be formed from materials known for high attenuation in the GHz frequency range, such as carbon-loaded foams, ferrite composites, or polymer sheets with conductive fillers. The absorbing material may be applied as a lining inside the housing or shaped into dedicated shields surrounding the radar antennas or lenses. In some implementations, the absorbing material may be combined with reflective or dielectric elements to create a hybrid beam-forming structure that both directs and confines the radar beam. The absorbing structures may be configured so that radar energy outside the main lobe is effectively dissipated as heat rather than being reflected back into the housing or toward unwanted surfaces.

[0050] The use of such absorbing elements may reduce false echoes from nearby components such as armrests, neck rests, tables and windows, or other interior surfaces, thereby enhancing the robustness of occupancy detection. The design allows the emitted radar lobes of the first and second sensors to be tailored to their respective seats with minimal overlap or crosstalk. The absorbing structures may thus contribute to more stable and repeatable detection results even when the assembly is installed in vehicles with differing interior geometries. In some variants, the absorbing material may be selectively positioned to balance beam width and attenuation, allowing for flexible adaptation to different train layouts or radar frequencies.

[0051] Materials commonly used for radar absorption include carbon-based foams, rubberized composites, and ferrite materials, each with properties that can be tuned to specific radar frequencies. The absorbing structures can be arranged as a ring or a segment of a ring.

[0052] Such a configuration may define an opening through which the radar signals are emitted, while the surrounding ring-shaped absorbing material attenuates energy radiated outside the desired angular range. The ring geometry may ensure that the main radar lobe maintains a well-confined shape, improving directionality and reducing the risk of unwanted side lobes. When implemented as a full ring, the absorbing material may completely surround the radar antenna or lens, leaving only a central aperture aligned with the intended emission direction.

[0053] In another embodiment, the absorbing structure may form a partial ring or segment, selectively shielding specific areas where unwanted reflections are most likely to occur, such as toward the roof, side windows, or dashboard. This approach may allow the P7318PC00

[0054] 10 radar beam to cover the relevant seat region while avoiding transmission into directions known to cause ghost echoes. The size and curvature of the ring or segment may be adapted to the beam width of the radar antenna, and the material thickness may be optimized to achieve sufficient absorption at the operating frequency.

[0055] In one embodiment, there may be one ring or a segment of a ring provided for each radar sensor. In other embodiments, several rings or ring segments may be used in combination to further refine the beam shape or to provide additional absorption in selected directions. The absorbing structures are not limited to circular geometries and may instead take other suitable forms, such as partial enclosures, curved panels, or irregularly shaped elements designed to conform to the available space or the specific beam pattern of the radar sensors. This flexibility in geometry allows the absorbing structures to be adapted to different sensor configurations and installation environments while maintaining effective suppression of unwanted radar reflections.

[0056] By forming the absorbing structure as a ring or segment of a ring, the assembly may achieve precise control of the radar field pattern without requiring complex antenna arrays or active beam steering. The design may also simplify manufacturing and calibration, since the absorber geometry can be integrated directly into the mechanical support or housing of the radar sensors. The ring-shaped absorber may further contribute to mechanical alignment of the radar lens or antenna, ensuring consistent beam orientation and performance across different installations.

[0057] In one embodiment, the absorbing structures may comprise a GHz-range radarabsorbing material selected to attenuate radar energy outside the intended emission paths of the first and second radar lobes. The material may be tuned to the operating frequency of the radar sensors so that off-axis or stray radiation is efficiently absorbed, preventing reflections within the housing or from nearby surfaces. This configuration may ensure that each radar lobe remains sharply defined toward its respective seat, reducing interference, crosstalk, and false detections.

[0058] In one embodiment, the absorbing structures may be configured to suppress stray reflections originating from structural elements located near the seats, such as armrests, neck rests, tables and windows, or mounting brackets. By absorbing radar energy that would otherwise reflect from these fixed components, the absorbing structures may prevent unwanted echoes that could interfere with the detection of an P7318PC00

[0059] 11 occupant. This configuration enhances the accuracy of the occupancy determination by ensuring that the received radar reflections predominantly represent signals from the seat surface or a seated person, rather than from adjacent objects or structures.

[0060] In one embodiment, the sensor assembly is configured such that a radar beam emitted by at least one of the radar sensors covers a spatial detection zone extending from the sensor toward and below the seat. The spatial detection cone may be a radar cone range. This spatial detection zone may be subdivided into a plurality of predefined spatial zones, including at least a body zone, a seat zone, and a floor zone. Each zone may correspond to a specific spatial region, a range zone, along the radar beam, defined by range (z), width (x) and / or height (y), such that reflections from different objects are separately identifiable. The processing circuitry may be configured to distinguish radar reflections originating from each zone, thereby allowing the system to interpret which parts of the special detection zone contain reflective objects and how these reflections change over time.

[0061] The division into zones may enable the processing circuitry to classify occupancy based on characteristic reflection patterns. For example, a person seated on the seat may produce strong reflections in the body zone while causing attenuation or absence of reflections in the seat and floor zones, as the body blocks radar signals from reaching those regions. Conversely, an empty seat may produce reflections primarily in the seat and floor zones but not in the body zone. By comparing signal amplitudes and delay information across the different zones - where delay represents depth along the beam based on the time-aligned receive bins - the system may determine whether the seat is occupied and, in some cases, distinguish between a human body and an inanimate object. Also, by comparing received signal over time may detect movement.

[0062] Variations in amplitude distribution together with the relative delay of returns from the body, seat, and floor regions may indicate a human presence when strong, shallower returns appear in the body zone while deeper returns from the seat and floor are reduced, whereas changes confined to the seat-zone amplitude and delay pattern without corresponding body-zone returns may indicate an object on the seat rather than a person.

[0063] The boundaries of the zones may be predefined during design or dynamically adjusted based on calibration or environmental conditions. The zoning concept may also allow P7318PC00

[0064] 12 exclusion of known fixed features such as metal seat structures or floor brackets, improving robustness against false detections. This design may result in higher measurement stability across different seat geometries and installation positions, while maintaining low computational complexity and privacy compared to full three- dimensional imaging systems.

[0065] In one embodiment, each of the predefined zones may correspond to a specific range interval or angular segment of the radar beam, the beam can be conceptually divided into portions defined by their direction in the X-Y plane relative to the radar sensor. This allows the processing circuitry to separate and analyze reflections based on distance or direction, enabling reliable identification of signals originating from the body, seat, or floor regions.

[0066] In one embodiment, the processing circuitry may be configured to determine that the seat is occupied when radar reflections are primarily detected within the body zone while being attenuated or absent within the seat and floor zones. This configuration may take advantage of the physical effect that a seated person reflects radar signals mainly from the upper body region, while the body itself shields the underlying seat and floor from the transmitted radar energy. In addition, the system may be capable of distinguishing other occupancy conditions, such as the presence of an object placed on the seat. For example, if no radar reflections are detected in the body zone but the reflection characteristics in the seat zone differ from those of an empty seat, such as by showing increased amplitude or altered phase patterns, the processing circuitry may classify the seat as containing an object rather than a person. This capability may allow the system to differentiate between a human occupant and inanimate items like a bag or a child seat, thereby improving the reliability and usefulness of the seat occupancy determination.

[0067] By comparing the intensity, phase characteristics, or Doppler information of the radar reflections from the respective zones, the processing circuitry may distinguish the presence of a person from an empty seat or an inanimate object placed on the seat surface. The relative strength and temporal variation of the reflections can indicate whether the reflecting surface corresponds to a stationary structure, or a living person.

[0068] The detection algorithm may involve comparing the relative amplitudes of reflected signals, computing reflection ratios between zones, or using threshold-based P7318PC00

[0069] 13 classification. In some cases, the system may apply temporal filtering to monitor changes in reflection strength as a person enters or leaves the seat. The criterion that reflections occur predominantly in the body zone and are reduced in the seat and floor zones may therefore represent a stable indication of true occupancy. This approach allows for reliable seat detection even under varying lighting, temperature, or material conditions, since the radar signal is independent of optical visibility.

[0070] By structuring the evaluation in this manner, the seat occupancy determination may become inherently more robust against false positives caused by reflective objects left on the seat or transient reflections from the vehicle interior. The zoning and comparative analysis may thus allow the system to identify a human occupant with higher certainty and lower computational complexity than full imaging or motion-based systems.

[0071] In one embodiment, the boundaries of the predefined zones may be adjustable based on calibration data or learning algorithms configured to improve the accuracy of occupancy detection. During installation or operation, the system may perform an automatic calibration sequence that determines the optimal distance ranges or angular limits for the body, seat, and floor zones. The calibration may account for variations in seat geometry, mounting position, or material reflectivity. Over time, learning algorithms may adapt these boundaries by analyzing historical radar data and correlating reflection patterns with confirmed occupancy states. By adjusting the zone boundaries dynamically, the system may maintain reliable performance across different vehicle types and usage conditions, optimizing the discrimination between occupied and unoccupied seats without requiring manual recalibration.

[0072] In one embodiment, the processing circuitry is configured to disregard radar reflections that correspond to predefined spatial zones associated with fixed structural components of the seat, such as an armrest, headrest support, or frame element. These components are known, static parts of the seat assembly that do not provide information relevant to occupancy detection but may produce strong radar echoes due to their reflective surfaces. By identifying and excluding such sectors from the active detection field, the system may effectively limit its analysis to those regions where a human occupant is expected to be present, such as the seat cushion and the space above it. P7318PC00

[0073] 14

[0074] The predefined spatial zones may be determined during system calibration or derived from geometric data of the seat structure. The processing circuitry may store this information as exclusion masks or angular range definitions corresponding to each radar sensor’s field of view. When radar reflections are received, the circuitry may compare the detected angles or ranges with the predefined exclusion sectors and discard data originating from those regions. This approach may reduce false positives caused by consistent reflections from seat components that remain unchanged regardless of occupancy state.

[0075] In some embodiments, the exclusion sectors may be dynamically updated based on vehicle configuration or sensor mounting variations. For instance, the system may perform a reference scan when no occupant is present, identify stable reflection points corresponding to fixed elements, and automatically classify them as regions to be ignored in subsequent measurements. By disregarding these reflections, the effective detection field becomes confined to zones directly related to occupant presence, improving both detection accuracy and computational efficiency. This selective exclusion mechanism may thus ensure that the seat occupancy sensor responds only to relevant reflections and remains robust even in complex seating environments or when seat materials and geometries differ between vehicle models.

[0076] In one embodiment, the absorbing structures may be positioned and dimensioned in correspondence with the predefined detection zones so that each absorbing element physically delimits or shields the radar field associated with a particular zone. The absorbing structures may be shaped to match the geometry of the body, seat, and floor zones, ensuring that radar energy outside these zones is absorbed before it can cause unwanted reflections. By coordinating the placement of the absorbing material with the spatial extent of the zones, the system may effectively limit its radar sensitivity to reflections originating only within those intended regions.

[0077] This coordinated design may prevent the radar sensors from responding to echoes coming from areas beyond the useful detection volume, such as surrounding panels, the window, or other seats. The result may be a cleaner and more stable radar signal, with reduced interference and improved distinction between the body, seat, and floor zones. The positioning and dimensions of the absorbing structures may be determined through calibration or simulation so that they correspond precisely to the angular and range boundaries of the zones defined in software. This arrangement allows the P7318PC00

[0078] 15 physical beam-shaping properties of the absorbing structures and the digital zonebased analysis to work together, producing a compact and robust sensing assembly that reliably detects seat occupancy while minimizing false echoes.

[0079] In one embodiment, the one or more absorbing structures may be arranged in combination with the first lens and / or the second lens so that the lenses focus the emitted radar signals in the desired direction while the absorbing structures attenuate unwanted energy outside the main radar lobes. The lens may act to concentrate and shape the outgoing radar beam, while the absorbing structures positioned in front of, around, or behind the lens may capture residual side lobes and backscattered signals that would otherwise cause interference or ghost echoes. This combination may ensure that only the focused portion of the radar energy is transmitted toward the target seat region, improving beam definition and measurement reliability.

[0080] The lens may act to concentrate and shape the outgoing radar beam, while the absorbing structures positioned in front of, around, or behind the lens may capture residual side lobes and backscattered signals that would otherwise cause interference or ghost echoes.

[0081] In one embodiment, the radar sensor may comprise a radar sensor in combination with a lens, and one or more absorbing elements arranged in specific positions relative to these components. To block radar signals emitted at very oblique angles directly from the radar sensor, an absorbing structure may be positioned around the sensor itself. This arrangement may prevent energy from leaving the sensor in undesired directions before it reaches the lens. To further suppress radar energy emitted just outside the intended field of the lens, additional absorbing material may be placed around or partially enclosing the lens. Such positioning may help define a sharp transition between the active beam area and the surrounding suppressed regions. In some embodiments, an absorbing element may also be arranged behind the lens, to absorb internal reflections and fine-tune the overall beam shape.

[0082] By combining the focusing function of the lens with the selective attenuation provided by the absorbing material, the emitted radar beam may become cleaner and more directional, with significantly reduced side lobes and backscatter. This configuration may improve angular selectivity and measurement stability without the need for complex beam-steering electronics. The coordinated design of the lens and absorber P7318PC00

[0083] 16 positions may therefore provide precise control of the radar lobe geometry, ensuring that the transmitted energy is concentrated toward the intended seat region.

[0084] The first radar sensor and the second radar sensor may operate in the millimeter band using a frequency in the range of 30 GHz to 300 GHz. The term "millimeter band" refers to a frequency range that corresponds to wavelengths between 1 millimeter and 10 millimeters.

[0085] The specific frequency range used within the millimeter band can vary based on regulatory requirements and the desired detection characteristics. For example, a frequency around 77 GHz may be used for long-range detection, while a frequency around 60 GHz may be more suitable for short-range, high-resolution detection. The radar sensors may also be designed to switch between different frequencies within this band, allowing them to adapt to different operating environments. This flexibility can be advantageous in scenarios where the sensor must operate in varying seat configurations or detect objects at different distances.

[0086] In one embodiment of the present disclosure, the radar sensors may be configured to operate in a 60 GHz band using a frequency in the range of 57 GHz to 64 GHz. The 60 GHz band is particularly suitable for high-density seat occupancy detection because it offers a high bandwidth, enabling the radar to capture more detailed information about the target area. This can help in resolving fine details and may minimize interference with other radar systems.

[0087] The radar sensors operating in this band may include specialized components, such as high-gain antennas and low-noise amplifiers, to optimize performance. In one example, the antennas may be designed as phased arrays, allowing the radar lobes to be electronically steered without moving parts. This configuration can enable the system to scan multiple seats rapidly, improving the speed and reliability of the seat occupancy detection.

[0088] In one embodiment of the present disclosure, the processing circuitry is configured to determine seat occupancy by measuring a first amplitude of the reflected first radar signals and comparing against a first threshold and / or measuring a second amplitude of the reflected second radar signals and comparing against a second threshold. The amplitude of a reflected radar signal is indicative of the strength of the reflection, which P7318PC00

[0089] 17 can vary depending on the size, shape, and material properties of the object causing the reflection. By setting amplitude thresholds, the sensor can filter out weak reflections that are unlikely to correspond to seat occupancy, such as small objects or stray reflections.

[0090] The thresholds may be dynamically adjusted based on environmental factors, such as the proximity of the sensor to nearby reflective surfaces or the expected range of occupant sizes. For example, the system may use a higher threshold for detecting adults and a lower threshold for detecting smaller occupants, such as children. In another variation, the system may use multiple thresholds to classify different types of occupancy, such as a person sitting still versus a person moving around. This capability enhances the sensor’s ability to provide accurate and context-aware seat occupancy data.

[0091] In one embodiment of the present disclosure, the processing circuitry is configured to exclude reflected radar signals outside a target distance range when determining seat occupancy for the first and / or second seat. The term "target distance range" refers to a predefined interval of distances measured from the radar sensor, within which reflections are considered relevant for detecting occupancy. This range may be defined based on the physical layout of the seats, the sensor’s installation position, and the expected placement of an occupant within the seat. By excluding radar signals from outside this range, the sensor can avoid interference from reflections caused by surfaces that are not part of the seat, such as tables, armrests, walls, luggage racks, or adjacent seats.

[0092] In one possible implementation, the target distance range may be adjusted dynamically based on real-time data. For example, if the sensor is installed on a high ceiling or on an overhead luggage rack, the distance range may be extended to cover the area between the sensor and the seat, while excluding reflections from the floor or nearby surfaces. In another example, the range may be shortened if the seats are located close to the sensor, ensuring that only reflections within the immediate vicinity of the seats are analyzed. This flexibility allows the sensor to be adapted for different seating configurations and installation heights, enhancing its accuracy across a variety of environments. P7318PC00

[0093] 18

[0094] The processing circuitry may employ different algorithms to implement the target distance filtering. One approach is to use time-of-flight (ToF) measurements, where the sensor calculates the distance of each reflection based on the time it takes for the radar signal to travel to the target and back. Another approach is to use frequency- modulated continuous wave (FMCW) radar, which measures distance by analyzing the frequency shift between the emitted and reflected signals. These methods enable precise distance measurement, ensuring that only reflections within the specified range are considered for seat occupancy determination.

[0095] In one embodiment of the present disclosure, the processing circuitry may be configured to analyze reflected radar signals in one or more time windows, wherein each time window corresponds to a reflection distance. In this context, a "time window" refers to a specific interval during which the radar sensor receives and processes reflected signals. Each time window represents a different depth or distance from the radar sensor, allowing the system to build a three-dimensional representation of the seat area. By isolating reflections from different depths, the sensor can distinguish between objects that are located at varying distances, such as a person sitting in a seat versus an item placed on a nearby shelf.

[0096] The use of multiple time windows enables the sensor to perform depth-based segmentation of the reflected radar data. For example, shorter time windows may be used to capture reflections from close-range objects, while longer time windows may be used for distant objects. This allows the system to filter out unwanted reflections from outside the target detection zone, improving the accuracy of seat occupancy determination. In one implementation, the time windows can be dynamically adjusted based on the characteristics of the reflected signals. For instance, if a strong reflection is detected within a particular time window, the system may narrow that window to focus on the reflection in more detail.

[0097] The time windows can also be used to implement advanced detection features, such as multi-layered analysis. For example, the system may use different time windows to separate reflections from the upper and lower parts of a seat, enabling it to detect whether a person is sitting upright or leaning back. This capability allows the sensor to provide more detailed information about the occupant’s posture and movement within the seat. P7318PC00

[0098] 19

[0099] In one embodiment of the present disclosure, the lengths of the one or more time windows may be adapted according to a reflection profile of the reflected radar signals. The "reflection profile" refers to the characteristics of the reflected radar signals, including amplitude, frequency, and duration, which vary depending on the shape, size, and material properties of the reflecting object. By adapting the time window lengths based on the reflection profile, the sensor can optimize its detection capabilities for different types of targets. For example, shorter time windows may be used for sharp, high-amplitude reflections indicative of a person’s body, while longer windows may be used for weaker, diffuse reflections caused by soft objects like cushions or clothing.

[0100] In one implementation, the time windows can be dynamically adjusted in response to changes in the reflection profile. For instance, if a reflection profile indicates the presence of multiple objects within the detection zone, the system may increase the number of time windows to isolate each object separately. This configuration allows the sensor to handle complex detection scenarios, such as distinguishing between a person holding a bag and an empty seat beside them. The ability to adapt time window lengths based on real-time data ensures that the sensor remains highly responsive to varying occupancy conditions.

[0101] In one embodiment of the present disclosure, the processing circuitry may be configured to determine seat occupancy by calculating a moving average of a number of reflected radar signals over time and comparing against a threshold. A "moving average" refers to a statistical technique that smooths out short-term fluctuations in data by averaging a series of data points over a defined period. This technique can help reduce the impact of transient changes, such as a person briefly leaning into the detection zone or moving their arms, which might otherwise cause false detections.

[0102] The use of a moving average allows the sensor to focus on sustained occupancy patterns rather than momentary changes. For example, if a person places a bag on a seat and then removes it quickly, the moving average will prevent this short-term event from being classified as seat occupancy. In contrast, if the bag remains on the seat for an extended period, the moving average will eventually reflect this change, allowing the system to update its occupancy status accordingly. The length of the moving average window can be adjusted depending on the expected frequency of movement in the environment. In high-traffic areas, a shorter window may be used to detect rapid changes, while a longer window may be used for more stable environments. P7318PC00

[0103] 20

[0104] The moving average can be calculated using different methods, such as a simple moving average, where each data point has equal weight, or a weighted moving average, where recent data points are given more importance. This flexibility allows the sensor to be fine-tuned for different operational requirements, ensuring that the occupancy determination remains robust under a variety of conditions.

[0105] In one embodiment of the present disclosure, the processing circuitry may be configured to distinguish between a fixed item and a human. The term "fixed item" refers to any non-human object that is stationary and remains in the detection zone for an extended period, such as a seat cushion, a bag, or other personal belongings. Differentiating between a fixed item and a human may be useful for accurate occupancy detection, as many false positives are caused by stationary objects that reflect radar signals similarly to a human occupant.

[0106] The sensor may use a combination of amplitude, frequency, and movement characteristics to distinguish between fixed items and humans. For example, a fixed item will typically produce a consistent reflection profile with minimal variation over time, whereas a human occupant’s reflection profile will vary due to small movements, such as breathing or shifting position. In one implementation, the sensor may analyze micro-movements within the detection zone to identify human presence. This technique involves detecting subtle changes in the radar signal caused by involuntary movements, such as a person’s chest rising and falling during respiration. If these micro-movements are absent, the system may classify the object as a fixed item.

[0107] In one variation, the system may use pattern recognition algorithms to identify specific reflection patterns associated with different types of fixed items. For instance, a bag placed on a seat may produce a distinct reflection shape that can be stored in the system’s memory and used for comparison during subsequent detections. This capability allows the sensor to provide a more nuanced classification of objects, reducing the likelihood of false positives and improving overall detection accuracy.

[0108] In one embodiment of the present disclosure, the processing circuitry is configured to exclude reflected first and / or second radar signals from predetermined distances associated with known fixed objects when determining seat occupancy for the first and / or second seat. This configuration allows the sensor to avoid false detections caused by stationary objects that are consistently present in the environment. The term P7318PC00

[0109] 21

[0110] “fixed items” can include structural components of the train, such as armrests, seatbacks, table edges, or overhead compartments, as well as personal items that passengers frequently place in specific locations, like bags stored on a particular rack. The processing circuitry may store a database of these fixed items and their associated distances relative to the sensor’s position, enabling it to filter out reflections originating from these locations.

[0111] In one embodiment of the present disclosure, the processing circuitry is configured to determine seat occupancy by analyzing patterns of the reflected first radar signals and / or the reflected second radar signals. This capability allows the system to go beyond simple amplitude or distance measurements and instead analyze more complex characteristics of the reflected signals, such as shape, texture, or temporal changes. The term “patterns” in this context refers to distinct features in the radar signal data, such as the frequency and amplitude variations, signal duration, or even subtle fluctuations caused by human movement.

[0112] Analyzing patterns enables the sensor to differentiate between a variety of scenarios, such as a person sitting upright, leaning, or holding a bulky object. In one possible implementation, the sensor may use machine learning algorithms to recognize specific patterns associated with different types of occupancy. For example, a neural network could be trained on a set of known patterns for human occupants and various inanimate objects, allowing the system to classify new reflections with high confidence. In another implementation, the processing circuitry may employ rule-based pattern recognition, using predefined criteria such as amplitude thresholds and frequency bands to identify different objects.

[0113] This ability to analyze patterns provides a higher degree of specificity in seat occupancy detection. For instance, the system could distinguish between an empty seat, a seat with a person sitting still, and a seat with a person actively moving. Such detailed classification can be beneficial for applications where knowing the exact type of seat occupancy is critical, such as dynamic seat allocation or safety monitoring systems.

[0114] In one embodiment of the present disclosure, the seat occupancy sensor is configured to detect the presence of one or more persons in the first seat and / or the second seat by applying minimum and maximum detection distances relative to the seat occupancy P7318PC00

[0115] 22 sensor being installed in a fixed position relative to the first seat and / or the second seat, such as on an underside of an overhead luggage rack.

[0116] The minimum detection distance refers to the closest point at which the sensor begins to analyze radar reflections, while the maximum detection distance sets the farthest point for analysis.

[0117] In one embodiment of the present disclosure, the minimum detection distance is between 0 and 50 cm and the maximum detection distance is between 60 and 150 cm. These specific ranges are selected to provide optimal coverage for typical train seating arrangements. A minimum detection distance of 0 to 50 cm ensures that reflections from the immediate surroundings, such as the rack or ceiling, are excluded, while a maximum detection distance of 60 to 150 cm captures the full seating area, including the occupant and any items they may have placed on the seat.

[0118] The exact distances can be customized during installation to match the specific layout of the train. For example, in a high-density seating area, the maximum detection distance might be shortened to prevent overlap between adjacent seats, whereas in a low-density, spacious seating area, the maximum detection distance might be extended to capture reflections from the full height of the seatback. This adaptability allows the sensor to maintain high accuracy across various seating configurations, ensuring that it only detects occupancy within the intended zone.

[0119] In one embodiment of the present disclosure, the seat occupancy sensor comprises a substantially flat backside to be attached or mounted on an item such as a ceiling or rack, and wherein the first radar sensor is disposed such that a general first direction of the first radar lobe has a first tilt angle in a first lateral direction (x) between 2° and 15° with respect to a general extension (z) perpendicular to the substantially flat backside, and / or wherein the second radar sensor is disposed such that a general second direction of the second radar lobe has a second tilt angle in the first lateral direction (x) between 2° and 15° with respect to a general extension (z) perpendicular to the substantially flat backside. This configuration enables the radar lobes to be directed precisely toward the seats, ensuring that each lobe covers its designated seat area. P7318PC00

[0120] 23

[0121] The flat backside allows for easy attachment to various surfaces, such as an overhead rack or a ceiling panel, using mounting hardware like screws, adhesive, or magnetic attachments.

[0122] The seat occupancy sensor may further comprise fastening means for securing the seat occupancy sensor to an item, such as an overhead luggage rack. The term “fastening means” refers to any mechanism, structure, or component used to attach the sensor assembly securely to a surface. These fastening means can include, but are not limited to, screws, brackets, adhesive mounts, magnetic fixtures, or snap-fit elements. The choice of fastening means may depend on the nature of the surface and the specific environmental conditions where the sensor is to be installed.

[0123] The seat occupancy sensor may further comprise a wedge element adapted to be arranged on a backside of the seat occupancy sensor towards an item onto which the seat occupancy sensor is fastened. The wedge element, as previously described, is a component used to adjust the orientation of the radar sensor when mounted on a flat or sloped surface. By changing the angle of the sensor relative to its mounting surface, the wedge element enables the radar lobes to be directed accurately towards the seats, ensuring that the detection areas are aligned with the seat positions. The wedge element may be designed to compensate for variations in vehicle interiors, such as different luggage rack geometries or rear shelf designs, which may otherwise result in a non-optimal mounting angle for the radar sensors. The wedge element may also allow adjustment for vehicles with different seat widths or spacing, so that each radar beam can be oriented precisely toward the intended seat region. By selecting a wedge with an appropriate angle or by providing an adjustable or interchangeable wedge structure, the same seat occupancy sensor assembly can be adapted for use in various vehicle models without requiring redesign of the radar housing or internal components. This enhances the flexibility of installation and simplifies retrofitting into existing vehicles.

[0124] The wedge element may be made of lightweight yet durable materials, such as plastic or aluminum, to provide structural stability while minimizing the overall weight of the sensor assembly. The backside of the seat occupancy sensor may include predefined slots or grooves to securely attach the wedge element, allowing for quick and easy installation. This design ensures that the wedge element remains firmly in place, even when subjected to vibrations or shocks from the vehicle’s movement. In one variation, P7318PC00

[0125] 24 the wedge element may have a textured surface or include anti-slip coatings to prevent any unwanted movement after installation.

[0126] In another implementation, the wedge element could be shaped to accommodate various mounting scenarios. For example, the element could be designed with a curved profile for installation on rounded surfaces, such as cylindrical overhead beams, or with a tapered edge for fitting into narrow gaps. These different shapes and configurations make the wedge element suitable for a wide range of vehicle interiors, ensuring that the sensor can be mounted in the optimal position for detecting seat occupancy.

[0127] In one embodiment of the present disclosure, the wedge element may be configured to adjust a first exit angle of the first radar signals and a second exit angle of the second radar signals relative to the item onto which the seat occupancy sensor is fastened.

[0128] The term “exit angle” refers to the angle at which the radar signals are emitted from the radar sensor relative to the mounting surface. By adjusting the exit angles of the radar signals, the wedge element ensures that the radar lobes are directed precisely towards the target seats, preventing signal spillover into adjacent areas and reducing interference.

[0129] In one embodiment of the present disclosure, the seat occupancy sensor may be configured for a first seat configuration of the first and second seats when the wedge element is not arranged on the seat occupancy sensor and for a second seat configuration of the first and second seats when the wedge element is arranged on the seat occupancy sensor. This feature allows a single sensor unit to be adapted for different seating layouts by simply adding or removing the wedge element. In the first configuration, where the wedge element is absent, the radar lobes may be directed downward in a default orientation, covering seats positioned directly beneath the sensor. This setup is ideal for standard seating arrangements where the seats are aligned uniformly.

[0130] In the second configuration, where the wedge element is present, the radar lobes can be tilted to cover seats that are offset or positioned at different angles relative to the sensor. The ability to switch between configurations using the wedge element makes the sensor highly versatile, allowing it to be quickly reconfigured for different train carriages or seating setups without requiring changes to the sensor hardware. P7318PC00

[0131] 25

[0132] In one embodiment of the present disclosure, the seat occupancy sensor may further comprise one or more inertial sensors configured to detect movement of a vehicle in which the seat occupancy sensor is installed. An “inertial sensor” in this context refers to a sensor that measures acceleration, rotation, and other motion-related parameters of the vehicle. Common types of inertial sensors include accelerometers, gyroscopes, and magnetometers. By detecting movement, the inertial sensor allows the seat occupancy sensor to adapt its operation based on the motion state of the vehicle, such as whether it is moving, stationary, accelerating, or decelerating.

[0133] The inertial sensor may be used to enable and disable the seat occupancy sensor assembly. It could also improve the accuracy of seat occupancy detection by compensating for motion-related noise in the radar signals. For example, when the vehicle is moving over rough terrain or navigating sharp turns, the inertial sensor can detect these conditions and alert the processing circuitry to filter out spurious reflections caused by the motion.

[0134] In another variation, the inertial sensor data may be used to optimize the sensor’s power consumption. For instance, when the vehicle is stationary, the processing circuitry may reduce the sensor’s radar transmission power or put certain components into standby mode, conserving energy.

[0135] In one embodiment of the present disclosure, the processing circuitry is configured to switch off at least a portion of the seat occupancy sensor or put the seat occupancy sensor in standby mode when the vehicle does not move for a predetermined period of time. This feature leverages the data from the inertial sensor to determine when the vehicle is idle. When the vehicle has been stationary for the predetermined period, the processing circuitry may deactivate some or all of the sensor’s components to reduce power consumption. The term “predetermined period of time” can refer to a fixed interval, such as 5 or 10 minutes, which may be adjustable depending on the operational requirements.

[0136] In one embodiment of the present disclosure, the seat occupancy sensor may further comprise a third radar sensor having a third radar lobe for detection of physical presence at a third seat in a third direction. The addition of a third radar sensor allows the seat occupancy sensor assembly to cover an additional seat, making it suitable for seating arrangements where three seats are positioned in close proximity, such as in P7318PC00

[0137] 26 three-seat rows in a train or airplane. The third radar sensor can be oriented in a direction distinct from the first and second radar sensors, ensuring that its radar lobe is focused specifically on the third seat and does not overlap significantly with the detection areas of the other sensors.

[0138] The third radar sensor may be integrated into the same housing as the first and second radar sensors, maintaining a compact design while providing expanded detection capabilities. Alternatively, the third sensor could be configured as an external module that communicates wirelessly or through a wired connection to the main sensor assembly. This modular approach allows for greater flexibility in configuring the sensor for different seating layouts, enabling easy addition or removal of the third radar sensor based on the required coverage area.

[0139] In one implementation, the third radar sensor may be configured to operate independently of the first and second sensors, allowing it to have its own detection parameters, such as range, beam width, and power settings. This independent configuration can be beneficial in complex seating environments, where the third seat may have different occupancy characteristics or where it is positioned at a different height or angle compared to the first and second seats. By providing a dedicated radar lobe for the third seat, the sensor assembly ensures accurate and reliable occupancy detection even in asymmetrical or staggered seating layouts.

[0140] In one embodiment of the present disclosure, the seat occupancy sensor may further comprise a fourth radar sensor having a fourth radar lobe for detection of physical presence at a fourth seat in a fourth direction. Similar to the inclusion of the third radar sensor, the addition of a fourth radar sensor expands the detection capabilities of the seat occupancy sensor assembly, making it suitable for monitoring four adjacent seats. This is particularly useful in high-capacity seating arrangements, such as in train carriages with four-seat configurations or in larger passenger vehicles.

[0141] The fourth radar sensor can be aligned in a fourth direction distinct from the first, second, and third sensors, ensuring that each seat is individually monitored without interference. In one possible implementation, the radar lobes of the four sensors may be shaped and directed to minimize overlap and ensure clear separation between the detection zones of each seat. This precise alignment helps maintain detection accuracy, even in densely packed seating areas. P7318PC00

[0142] 27

[0143] The fourth radar sensor may also be used in conjunction with the other sensors to perform more complex occupancy analysis. For example, the processing circuitry could be configured to compare data from all four radar sensors to detect patterns indicative of group behavior, such as multiple people occupying adjacent seats. This capability allows the sensor assembly to provide more detailed insights into seat utilization, making it useful for advanced applications like dynamic seat allocation or passenger comfort monitoring.

[0144] In one embodiment of the present disclosure, the seat occupancy sensor may further comprise one or more infrared sensors, such as one or more thermopile infrared sensors, configured to sense infrared radiation from the first radar lobe and / or the second radar lobe to distinguish between presence of an animate being and an inanimate object. The term “thermopile infrared sensor” refers to a type of infrared sensor that detects temperature differences by measuring the heat emitted by objects within its field of view. This feature enhances the sensor’s ability to differentiate between living occupants and inanimate objects, as living beings typically emit higher levels of infrared radiation compared to non-living items.

[0145] By combining radar data with infrared data, the sensor can achieve a higher degree of confidence in determining seat occupancy. For example, if the radar signals indicate the presence of an object but the infrared sensor does not detect a corresponding heat signature, the processing circuitry can classify the object as inanimate, such as a bag or coat. Conversely, if both the radar and infrared sensors detect the presence of an object with a strong heat signature, it can be classified as an animate being, such as a person.

[0146] In one possible implementation, the infrared sensors may be configured to monitor the entire radar lobe, providing a broad coverage area that overlaps with the radar detection zones. This overlapping coverage ensures that every object detected by the radar sensors is also analyzed by the infrared sensors. In another implementation, the infrared sensors could be focused on specific zones within the radar lobe, allowing for targeted analysis of critical areas, such as the seat cushion or backrest, where human occupants are most likely to emit detectable levels of infrared radiation. P7318PC00

[0147] 28

[0148] In one embodiment of the present disclosure, the processing circuitry is configured to activate the first radar sensor and / or the second radar sensor for a limited amount of time at predetermined intervals. This feature, referred to as “duty cycling,” allows the sensor to conserve power by only activating the radar sensors periodically instead of continuously. The term “predetermined intervals” refers to specific time intervals, such as every few seconds or minutes, during which the radar sensors are briefly powered on to perform a detection sweep.

[0149] The use of predetermined intervals can be particularly useful in environments where continuous monitoring is not required, such as during periods of low activity or when the vehicle is stationary. For example, the processing circuitry may activate the sensors every 30 seconds to perform a quick occupancy check, and if no changes are detected, the sensors are turned off again until the next interval. This approach reduces the overall power consumption of the system, extending the lifespan of battery-operated sensors and reducing the need for frequent recharging or replacement. If a person leaves the seat, i.e. the sensor assembly goes from detecting an occupied state to an unoccupied state, the interval for activating the sensor may be smaller for a time period.

[0150] In one implementation, the interval duration may be dynamically adjusted based on environmental conditions or detected activity. For instance, if the vehicle is moving or if passengers are frequently entering and exiting the seats, the intervals may be shortened to ensure more frequent monitoring. Conversely, if the vehicle is stationary or if no activity is detected, the intervals may be lengthened to conserve power. This dynamic interval adjustment allows the sensor to adapt its operation based on real-time conditions, providing efficient and reliable seat occupancy detection.

[0151] The processing circuitry may be configured to handle transitioning between "occupied" and "unoccupied" states. When a seat transitions from occupied to unoccupied, it is important to account for potential short-term movements or momentary absences by the occupant. For example, a passenger might briefly stand up or adjust their position without fully leaving the seat. Therefore, the transition from occupied to unoccupied is typically a slower process, allowing for multiple detection cycles over a defined period. In this case, the radar sensors may perform several consecutive scans with time intervals between them to ensure that the seat is truly vacant before confirming the unoccupied status. This repeated checking helps prevent false positives. In one P7318PC00

[0152] 29 implementation, the system may require a certain number of consecutive "unoccupied" readings, taken over a few seconds or minutes, before changing the seat's status to unoccupied.

[0153] Conversely, the transition from unoccupied to occupied may be implemented to be faster to ensure real-time seat availability data. This is particularly important to prevent a situation where a seat is booked or allocated as available when it is actually occupied. The radar sensors can be configured to increase the detection frequency in this scenario, ensuring that the system promptly updates the occupancy status and prevents other passengers or booking systems from mistakenly considering the seat as available.

[0154] Fig. 1 shows an exploded view of one embodiment of the presently disclosed seat occupancy sensor assembly 100, illustrating an example of the various components and their arrangement within the seat occupancy sensor assembly 100. The seat occupancy sensor assembly 100, includes a first radar sensor 101 , which is used to emit and receive radar signals for detecting physical presence at a designated seat. Typically there is also a second radar sensor 102. The housing 106 encloses the internal components, providing structural support and protection. The wireless transceiver 103 is included for transmitting and(or receiving data to / from an external unit, enabling communication between the sensor and external systems, such as a central control unit or a train’s onboard monitoring system. The power supply 104, in the example in the form of two batteries, is responsible for powering the seat occupancy sensor assembly and its components, and it may be integrated with a power supply cover 108. The PCB for radar processing circuitry 107 is the circuit board that holds the radar sensor components and associated electronics, including the processing circuitry 105, which is disposed on the bottom side of the PCB for radar processing circuitry 107 in this example. There is an absorbing structure 109, made of materials that dampen unwanted radar signals. The PCB holder 111 provides mechanical stability to the radar PCB. The assembly also includes mounting tape 112, which is used to secure the seat occupancy sensor 100 to an item, such as a ceiling or overhead rack.

[0155] Figs. 2A and 2B show two cross-sections of one embodiment of the presently disclosed seat occupancy sensor assembly 100, providing a view of the internal layout and the relative positioning of the components. In Fig. 2A, the seat occupancy sensor 100 is P7318PC00

[0156] 30 shown with the first radar sensor 101 and the second radar sensor 102 arranged within the housing 106. The housing 106 encloses the radar sensors. The first and second radar sensors 101 , 102 are oriented at specific angles to optimize their coverage of the seats. Additionally, the cross-sectional view shows the inclusion of two lenses 110, which shapes and directs the radar signals emitted by the radar sensors. The lenses 110 ensures that the radar lobes are formed with the correct beam width and focus.

[0157] In Fig. 2B, the cross-section further illustrates the positioning of components, including the wireless transceiver 103 and the power supply 104, which are integrated into the seat occupancy sensor assembly 100 to enable wireless communication and provide power to the system, respectively. The absorbing structure 109 is positioned within the housing. The lens 110 is configured to shape the radar beams emitted by the radar sensors, ensuring that the detection areas are precisely aligned with the seats. The absorbing structure 109, in this embodiment, is arranged strategically to focus the emitted radar signals and prevent signal leakage into adjacent areas, thereby optimizing the sensor’s performance.

[0158] Fig. 3 shows a perspective view of one embodiment of the presently disclosed seat occupancy sensor assemblylOO. The perspective view illustrates the sensor’s compact design. The perspective view highlights the compact and streamlined design of the sensor, making it suitable for installation in various vehicle configurations.

[0159] The disclosure further relates to a method for determining seat occupancy, the method comprising the steps of providing a seat occupancy sensor comprising at least a first radar sensor and a second radar sensor; activating the first radar sensor to emit first radar signals in a first radar lobe towards a first seat; activating the second radar sensor to emit second radar signals in a second radar lobe towards a second seat; receiving and analyzing reflected first radar signals from the first radar lobe to determine seat occupancy for the first seat; and receiving and analyzing reflected second radar signals from the second radar lobe to determine seat occupancy for the second seat. This method enables detection of seat occupancy for multiple seats using a single sensor assembly, ensuring a high level of accuracy even in dynamic seating environments where passengers may frequently change positions. The steps are not necessarily sequential. P7318PC00

[0160] 31

[0161] Fig. 4 shows a flowchart of method for determining seat occupancy (200). The method begins with providing a seat occupancy sensor comprising at least a first radar sensor and a second radar sensor (201). Then the first radar sensor emits first radar signals in a first radar lobe towards a first seat (201); and the second radar sensor emits second radar signals in a second radar lobe towards a second seat (202). The method further comprises the steps of receiving and analyzing reflected first radar signals from the first radar lobe to determine seat occupancy for the first seat (203); and receiving and analyzing reflected second radar signals from the second radar lobe to determine seat occupancy for the second seat (204).

[0162] The processing circuitry may include one or more processors, microcontrollers, or digital signal processors (DSPs) configured to execute software instructions and process signals received from the radar sensors. The processing circuitry may further include memory components, such as volatile memory (e.g., RAM) and non-volatile memory (e.g., ROM, flash memory), for storing program instructions, sensor calibration data, and occupancy detection algorithms. The software instructions executed by the processing circuitry can perform various signal processing tasks, including filtering, noise reduction, and pattern recognition, to accurately determine seat occupancy.

[0163] The processing circuitry may be operatively connected to the radar sensors and other components, such as the power supply and the communication module, via internal communication buses or signal lines. The processing circuitry can control the activation and deactivation of the radar sensors based on predefined criteria, such as detecting motion, receiving commands from an external control unit, or operating on a predetermined schedule.

[0164] The processing circuitry may further communicate the detected seat occupancy status to external systems through a wireless transceiver or a wired communication module. This communication may be performed using various wireless communication protocols, such as Wi-Fi, Bluetooth, LoRaWAN or proprietary RF communication standards, depending on the specific implementation. In one embodiment, the processing circuitry may send periodic status updates or transmit an alert when a change in seat occupancy is detected, enabling integration with external seat management or monitoring systems. P7318PC00

[0165] 32

[0166] The communication can be directed to a cloud service that aggregates and processes occupancy data from multiple seat occupancy sensors, providing real-time insights into seat availability across an entire vehicle, such as a train. The cloud service may be designed to receive occupancy data from all seats within a train carriage or across multiple carriages, allowing for centralized visualization of seat utilization. This data can be displayed on a user interface accessible to operators, showing the real-time status of each seat, such as whether it is currently occupied or available.

[0167] One potential benefit of integrating seat occupancy data with a cloud service is the potential to re-sell seats that have previously been sold but are not being used. For instance, if a seat is detected as unoccupied after a passenger was supposed to have boarded, the cloud service may flag the seat as available for re-sale. In such cases, the cloud service can communicate with a booking system to re-list the seat, offering it to other passengers in real time. By integrating seat occupancy data with a cloud-based system, train operators are empowered to dynamically manage seat availability and reduce unused capacity.

[0168] Reference numbers

[0169] 100 - seat occupancy sensor assembly

[0170] 101 - first radar sensor

[0171] 102 - second radar sensor

[0172] 103 - wireless transceiver

[0173] 104 - power supply

[0174] 105 - processing circuitry

[0175] 106 - housing

[0176] 107 - PCB for radar processing circuitry

[0177] 108 - power supply cover

[0178] 109 - absorbing structure

[0179] 110 - lens

[0180] 111 - PCB holder

[0181] 112 - mounting tape

[0182] Further details

[0183] 1. A seat occupancy sensor assembly comprising: P7318PC00

[0184] 33 a first radar sensor having a first radar lobe for detection of physical presence at a first seat in a first direction; a second radar sensor having a second radar lobe for detection of physical presence at a second seat in a second direction; at least one wireless transceiver for wireless communication with an external unit; at least one power supply for powering the seat occupancy sensor; processing circuitry configured to activate the first radar sensor to emit first radar signals in the first radar lobe and to activate the second radar sensor to emit second radar signals in the second radar lobe, and to receive and analyze reflected first and second radar signals to determine seat occupancy for the first and second seats.

[0185] 2. The seat occupancy sensor according to item 1 , wherein the first radar sensor comprises a first lens for forming and / or directing the first radar signals in the first direction, and wherein the second radar sensor comprises a second lens for forming and / or directing the second radar signals in the second direction

[0186] 3. The seat occupancy sensor according to any one of the preceding items, further comprising one or more shielding structures made of a reflecting material arranged to limit the first radar sensor to emit the first radar signals in a desired direction in the first radar lobe and to limit the second radar sensor to emit the second radar signals in a desired direction in the second radar lobe.

[0187] 4. The seat occupancy sensor according to any one of the preceding items, further comprising one or more absorbing structures, wherein the one or more absorbing structures are made of, or lined with, a material capable of absorbing emitted radar signals to limit the first radar sensor to emit the first radar signals in a desired direction in the first radar lobe and to limit the second radar sensor to emit the second radar signals in a desired direction in the second radar lobe.

[0188] 5. The seat occupancy sensor according to any one of the preceding items, wherein the first radar sensor and the second radar sensor operate in the millimeter band, using a frequency in the range of 30 GHz to 300 GHz. P7318PC00

[0189] 34

[0190] 6. The seat occupancy sensor according to item 5, wherein the first radar sensor and the second radar sensor operate in a 60 GHz band, using a frequency in the range of 57 GHz to 64 GHz.

[0191] 7. The seat occupancy sensor according to any one of the preceding items, wherein the processing circuitry is configured to determine seat occupancy by measuring a first amplitude of the reflected first radar signals and comparing against a first threshold and / or measuring a second amplitude of the reflected second radar signals and comparing against a second threshold.

[0192] 8. The seat occupancy sensor according to any one of the preceding items, wherein the processing circuitry is configured to exclude reflected first and / or second radar signals outside a target distance range when determining seat occupancy for the first and / or second seat.

[0193] 9. The seat occupancy sensor according to any one of the preceding items, wherein the processing circuitry is configured to analyze reflected first radar signals and / or second radar signals in one or more time windows, wherein each time window corresponds to a reflection distance.

[0194] 10. The seat occupancy sensor according to item 9, wherein lengths of the one or more time windows are adapted according to a reflection profile of the reflected first radar signals and / or second radar signals.

[0195] 11 . The seat occupancy sensor according to item 10, wherein the processing circuitry is configured to use a smaller time window for more distinct reflected energies at a given depth or depth interval and a larger time window for less distinct reflected energies at a given depth or depth interval.

[0196] 12. The seat occupancy sensor according to any one of the preceding items, wherein the processing circuitry is configured to determine seat occupancy by calculating a moving average of a number of reflected first radar signals over time and comparing against a first threshold and / or calculating a moving average of a number of reflected second radar signals over time and comparing against a second threshold. P7318PC00

[0197] 35

[0198] 13. The seat occupancy sensor according to item 12, wherein the processing circuitry is configured to distinguish between a fixed item and a human.

[0199] 14. The seat occupancy sensor according to any one of the preceding items, wherein the processing circuitry is configured to activate the first radar sensor and / or the second radar sensor for a limited amount of time at predetermined intervals.

[0200] 15. The seat occupancy sensor according to item 14, wherein the predetermined intervals are dynamically adjusted based on environmental conditions or detected activity.

[0201] 16. The seat occupancy sensor according to any one of the preceding items, wherein the processing circuitry is configured to exclude reflected first and / or second radar signals from predetermined distances associated with known fixed objects when determining seat occupancy for the first and / or second seat.

[0202] 17. The seat occupancy sensor according to any one of the preceding items, wherein the processing circuitry is configured to determine seat occupancy by analyzing patterns of the reflected first radar signals and / or the reflected second radar signals.

[0203] 18. The seat occupancy sensor according to any one of the preceding items, wherein the seat occupancy sensor is configured to detect the presence of one or more persons in the first seat and / or the second seat by applying minimum and maximum detection distances relative to the seat occupancy sensor being installed on an underside of an overhead luggage rack.

[0204] 19. The seat occupancy sensor according to item 16, wherein the minimum detection distance is between 0 and 50 cm and wherein the maximum detection distance is between 60 and 150 cm.

[0205] 20. The seat occupancy sensor according to any one of the preceding items, wherein the seat occupancy sensor comprises a substantially flat backside to be attached or mounted on an item, such as a ceiling or rack, and wherein the first radar sensor is disposed such that a general first direction of the first radar P7318PC00

[0206] 36 lobe has a first tilt angle in a first lateral direction (x) between 2° and 15° with respect to a general extension (z) perpendicular to the substantially flat backside, and / or wherein the second radar sensor is disposed such that a general second direction of the second radar lobe has a second tilt angle in the first lateral direction (x) between 2° and 15° with respect to a general extension (z) perpendicular to the substantially flat backside.

[0207] 21. The seat occupancy sensor according to item 20, wherein the first radar sensor is disposed such that the first radar lobe has a further third tilt angle in a second lateral direction (y) between 2° and 15° with respect to the general extension (z), wherein the first lateral direction (x) and the second lateral direction (y) are perpendicular, and / or wherein the second radar sensor is disposed such that the second radar lobe has a further fourth tilt angle in a second lateral direction (y) between 2° and 15° with respect to the general extension (z), wherein the first lateral direction (x) and the second lateral direction (y) are perpendicular.

[0208] 22. The seat occupancy sensor according to any one of the preceding items, further comprising fastening means for securing the seat occupancy sensor to an item, such as an overhead luggage rack.

[0209] 23. The seat occupancy sensor according to any one of the preceding items, further comprising a wedge element adapted to be arranged on a backside of the seat occupancy sensor towards an item onto which the seat occupancy sensor is fastened.

[0210] 24. The seat occupancy sensor according to item 23, wherein the wedge element is configured to adjust a first exit angle of the first radar signals and a second exit angle of the second radar signals relative to the item onto which the seat occupancy sensor is fastened.

[0211] 25. The seat occupancy sensor according to any one of items 23 to 24, wherein the seat occupancy sensor is configured for a first seat configuration of the first and second seats when the wedge element is not arranged on the seat occupancy sensor, and wherein the seat occupancy sensor is configured for a second seat configuration of the first and second seats when the wedge element is arranged on the seat occupancy sensor. P7318PC00

[0212] 37

[0213] 26. The seat occupancy sensor according to any one of the preceding items, further comprising one or more inertial sensors configured to detect movement of a vehicle in which the seat occupancy sensor is installed.

[0214] 27. The seat occupancy sensor according to item 26, wherein the processing circuitry is configured to switch off at least a portion of the seat occupancy sensor, or put the seat occupancy sensor in standby mode, when the vehicle does not move for a predetermined period of time.

[0215] 28. The seat occupancy sensor according to any one of the preceding items, wherein one of the first radar sensor and the second radar sensor is configured to be selectively disabled.

[0216] 29. The seat occupancy sensor according to any one of the preceding items, further comprising a third radar sensor having a third radar lobe for detection of physical presence at a third seat in a third direction.

[0217] 30. The seat occupancy sensor according to any one of the preceding items, further comprising a fourth radar sensor having a fourth radar lobe for detection of physical presence at a fourth seat in a fourth direction.

[0218] 31. The seat occupancy sensor according to any one of the preceding items, further comprising one or more infrared sensors, such as one or more thermopile infrared sensors, configured to sense infrared radiation from the first radar lobe and / or the second radar lobe to distinguish between presence of an animate being and an inanimate object.

[0219] 32. The seat occupancy sensor according to any one of the preceding items, wherein the processing circuitry is configured to activate the first radar sensor and / or the second radar sensor for a limited amount of time at predetermined intervals.

[0220] 33. A method for determining seat occupancy, the method comprising the steps of: providing a seat occupancy sensor comprising at least a first radar sensor and a second radar sensor; P7318PC00

[0221] 38 activating the first radar sensor to emit first radar signals in a first radar lobe towards a first seat; activating the second radar sensor to emit second radar signals in the second radar lobe towards a second seat; receiving and analyzing reflected first radar signals from the first radar lobe to determine seat occupancy for the first seat; receiving and analyzing reflected second radar signals from the second radar lobe to determine seat occupancy for the second seat. The method according to item 33 using the seat occupancy sensor according to any one of items 1-32.

Claims

P7318PC0039Claims1. A seat occupancy sensor assembly comprising: at least a first radar sensor having a first radar lobe for detection of physical presence at a first seat in a first direction; at least one wireless transceiver for wireless communication with an external unit; at least one power supply for powering the seat occupancy sensor; processing circuitry configured to activate the first radar sensor to emit first radar signals in the first radar lobe, and to receive and analyze reflected radar signals to determine seat occupancy for the first seat; one or more absorbing structures, wherein the one or more absorbing structures are made of, or lined with, a material capable of absorbing emitted radar signals to limit the first radar sensor to emit the first radar signals in a desired direction in the first radar lobe; and a housing enclosing the first radar sensor, the at least one wireless transceiver, the at least one power supply, the processing circuitry, and the one or more absorbing structures.

2. The seat occupancy sensor according to claim 1 , wherein the one or more absorbing structures comprises a GHz-range radar-absorbing material configured to attenuate radar energy that deviates from the desired direction in the first radar lobe.

3. The seat occupancy sensor according to any one of the preceding claims, wherein the one or more absorbing structures is / are configured to suppress stray reflections from adjacent structural elements of the first seat.

4. The seat occupancy sensor according to any one of the preceding claims, wherein the sensor assembly is configured such that a radar beam of at least one of the radar sensors covers a spatial detection zone, the spatial detection zone being subdivided into a plurality of predefined zones including at least a body zone, a seat zone, and a floor zone, wherein the processing circuitry is configured to distinguish between radar reflections from the body zone, the seat zone, and the floor zone.P7318PC00405. The seat occupancy sensor according to claim 4, wherein each of the predefined zones corresponds to a respective range interval or angular segment of the radar beam.

6. The seat occupancy sensor according to any one of claims 4-5, wherein the processing circuitry is configured to determine that the seat is occupied when radar reflections are detected predominantly within the body zone and attenuated within the seat zone and the floor zone.

7. The seat occupancy sensor according to any one of claims 4-6, wherein the boundaries of the predefined zones are adjustable based on calibration data or learning algorithms configured to optimize discrimination between occupied and unoccupied states.

8. The seat occupancy sensor according to any one of the preceding claims, wherein the processing circuitry is configured to disregard radar reflections corresponding to predefined spatial zones associated with fixed seat components, such as an armrest or frame element, such that an effective detection field of the seat occupancy sensor is limited to zones relevant for detecting an occupant.

9. The seat occupancy sensor according any one of claims 5-8, wherein the one or more absorbing structures are positioned and dimensioned in correspondence with the predefined zones so as to limit radar sensitivity to reflections originating within the body zone, the seat zone, and the floor zones, thereby reducing interference from regions outside the spatial detection zone.

10. The seat occupancy sensor according to any one of the preceding claims, further comprising a first lens for forming and / or directing the first radar signals in the first direction.11 . The seat occupancy sensor according to claim 10, wherein the one or more absorbing structures is / are arranged in combination with the first lens such that the first lens focuses the emitted radar signals while the one or more absorbing structure absorbs residual side lobes and backscatter energy.P7318PC004112. The seat occupancy sensor according to any one of the preceding claims, further comprising a second radar sensor having a second radar lobe for detection of physical presence at a second seat in a second direction.

13. The seat occupancy sensor according to any one of the preceding claims, further comprising one or more shielding structures made of a reflecting material arranged to limit the first radar sensor to emit the first radar signals in a desired direction in the first radar lobe and to limit the second radar sensor to emit the second radar signals in a desired direction in the second radar lobe.

14. The seat occupancy sensor according to any one of the preceding claims, wherein the processing circuitry is configured to analyze reflected first radar signals and / or second radar signals in one or more time windows, wherein each time window corresponds to a reflection distance, wherein lengths of the one or more time windows are adapted according to a reflection profile of the reflected first radar signals and / or second radar signals.

15. The seat occupancy sensor according to claim 14, wherein the processing circuitry is configured to use a smaller time window for more distinct reflected energies at a given depth or depth interval and a larger time window for less distinct reflected energies at a given depth or depth interval.

16. The seat occupancy sensor according to any one of the preceding claims, wherein the processing circuitry is configured to activate the first radar sensor and / or the second radar sensor for a limited amount of time at predetermined intervals.

17. The seat occupancy sensor according to claim 16, wherein the predetermined intervals are dynamically adjusted based on environmental conditions or detected activity.

18. The seat occupancy sensor according to any one of the preceding claims, wherein the processing circuitry is configured to exclude reflected first and / or second radar signals from predetermined distances associated with known fixed objects when determining seat occupancy for the first and / or second seat.P7318PC004219. The seat occupancy sensor according to any one of the preceding claims, wherein the seat occupancy sensor is configured to detect the presence of one or more persons in the first seat and / or the second seat by applying minimum and maximum detection distances relative to the seat occupancy sensor being installed in a fixed position relative to the first seat and / or the second seat, such as on an underside of an overhead luggage rack.

20. The seat occupancy sensor according to any one of the preceding claims, further comprising a wedge element adapted to be arranged on a backside of the seat occupancy sensor towards an item onto which the seat occupancy sensor is fastened.

21. The seat occupancy sensor according to any one of the preceding claims, further comprising one or more inertial sensors configured to detect movement of a vehicle in which the seat occupancy sensor is installed.

22. The seat occupancy sensor according to any one of the preceding claims, wherein the processing circuitry is configured to switch off at least a portion of the seat occupancy sensor, or put the seat occupancy sensor in standby mode, when the vehicle does not move for a predetermined period of time.

23. The seat occupancy sensor according to any one of the preceding claims, further comprising one or more infrared sensors, such as one or more thermopile infrared sensors, configured to sense infrared radiation from the first radar lobe and / or the second radar lobe to distinguish between presence of an animate being and an inanimate object.

24. A method for determining seat occupancy, the method comprising the steps of: providing a seat occupancy sensor comprising at least a first radar sensor having a first radar lobe for detection of physical presence at a first seat in a first direction; and one or more absorbing structures made of, or lined with, a material capable of absorbing emitted radar signals to limit the first radar sensor to emit the first radar signals in a desired direction in the first radar lobe; activating the first radar sensor to emit first radar signals in the first radar lobe towards the first seat;P7318PC0043 directing the emitted radar signals using the one or more absorbing structures such that radar energy deviating from desired directions is absorbed; receiving and analyzing reflected first radar signals from the first radar lobe to determine seat occupancy for the first seat.

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