WO2014173724A1

WO2014173724A1 - Sensing within a region

Info

Publication number: WO2014173724A1
Application number: PCT/EP2014/057561
Authority: WO
Inventors: Jurgen Mario Vangeel; Michel Albertus Theodorus Klein Swormink; Roger Peter Anna Delnoij; Johannes Jozef Wilhelmus Kalfs; Johannes Martinus Maria Hensing; Petrus Antonius Verbeek
Original assignee: Koninklijke Philips N.V.
Priority date: 2013-04-26
Filing date: 2014-04-15
Publication date: 2014-10-30

Abstract

A signal processing module for use with a receiver for receiving echoes of an emitted signal. The signal processing module comprises sensing logic for performing sensing based on the echoes, and an event filter. The event filter is configured to detect a respective direction from which each of said echoes is received at the receiver, and based thereon to limit the sensing to a sensing region having a directional dependency relative to the receiver. A sensing result is reported in dependence on the respective direction detected for one or more of the echoes being consistent with the directional dependency of the sensing region.

Description

SENSING WITHIN A REGION

TECHNICAL FIELD

The present disclosure relates to the sensing of a being or other object within a region of a space. For example the sensing may be used to control one or more lighting devices in dependence on a detected occupancy within a room, corridor, or other indoor or outdoor space; or for other sensing applications.

BACKGROUND

In current lighting applications, energy efficiency is a more and more important subject.

One possible way to reduce the energy consumption of a lighting system is to switch off or dim the lights when no persons are present, and conversely to switch on the lights when someone is present. In order to do this, the presence of any people in the relevant space has to be detected (e.g. to detect whether there is anyone present in a certain room or area of a room). The presence of a person in a space may be described as occupancy.

Different types of occupancy sensors or presence sensors are currently in use. Most of these sensors are motion sensors and use a passive infrared (PIR) sensor to detect motion.

Another way of detecting the presence of a person is to use an active sensing technique whereby one or more waves are emitted into the space in question and presence is detected based on echoes received back. One technology suitable for use in active sensing is ultrasound (US). An active ultrasound presence detector sends out a signal in the form of a series of bursts of acoustic waves (or a continuous wave) at an ultrasonic frequency, e.g. 40kHz. The sensor then uses the echoes it receives back from the environment to determine whether there is presence in that environment, e.g. in a room. Different methods can be used for this, for example Doppler shift measurements, time-of- flight measurements, and/or moving target indicator (MTI) processing.

Such presence information can be used to switch on or off a luminaire or a group of luminaires. The technique may be combined with a timer so that the light is only switched off if no presence is detected after a certain time (e.g. to avoid "false offs" when a person is present but not moving much). A sensor equipped for sensing over a certain range will sometimes be mounted in a space with a significantly smaller area. For example, a so-called large area sensor designed to sense presence in an area > 80 m² may end up being mounted in a room of a cellular office space with a much smaller area, e.g. of only 20m². A problem arising in this situation is that a person passing by outside the desired area may inadvertently trigger a detection. For example, a person passing the door of the office or other room may

inadvertently trigger a detection in the room, as the sensor will be sensing beyond the area of this room. Similarly a person passing along an adjacent corridor may trigger a detection if the office partitions are not sufficiently insulating and permit too much sound to travel through. This may have the undesired consequence that energy savings are not met when there are many triggers outside the area of interest.

Other applications may occur where it is desirable to restrict the region in which a sensor will sense presence.

A valued attribute of a PIR sensor, for presence detection, is that its detection area can be adjusted. This is useful when a PIR sensor's maximum sensing range exceeds a desired detection area, and encroaches on an area where detecting motion or other presence information is not desired. Common methods to limit detection area rely on reducing sensitivity and increasing thresholds, which often have undesired side-effects in the sensing area of interest as well. Although the detection area of a PIR sensor can be adjusted, doing so generally reduces its sensitivity. This means reducing the input gain of the front-end so that movements at the edge of the detection area no longer provide a large enough signal to exceed a threshold level. This may be undesirable. For instance, unwanted side effect of this method is that it reduces sensitivity everywhere and so makes the system more susceptible to "false offs" - i.e. as a result of the reduced sensitivity of the PIR sensor, the lights in an office may be switched off in response to an occupant's movements not being detected. Also, adjusting the detection area is, in essence, just reducing or increasing the radius of a detection circle. Thus, with a PIR sensor, the detection area is generally a circle which either: i) fits within a square room and thus would be unable to detect motion in the corners of the room; or ii) contains a square room within it and thus can potentially detect motion outside the room, e.g. through an open door or window.

Currently ultrasound sensors do not have a mechanism to limit detection area. Hence the only way to affect the detection region is by the positioning of the sensor and/or using physical (acoustically insulating) barriers or obstacles to block echoes from regions that are not desired. One known approach is to use mechanical shutters. SUMMARY

The known approach of using mechanical shutters is thought to be inaccurate. A better solution would be desirable.

According to one aspect disclosure herein, there is provided a signal processing module for use with a receiver for receiving echoes of an emitted signal. The signal processing comprises sensing logic for performing sensing based on said echoes, and an event filter. The event filter is configured to detect a respective direction from which each of said echoes is received at the receiver, and based thereon to limit said sensing to a sensing region having a directional dependency relative to the receiver. That is, a sensing result is reported in dependence on the respective direction detected for one or more of said echoes being consistent with the directional dependency of the sensing region.

Hence, the disclosed technique does not rely on blocking echoes from unwanted angles. Rather, it may potentially receive echoes from any angle, but processes information on the received echoes in order to determine the direction from which they were received and apply a condition to the direction. Thus a received echo only triggers a positive result if it meets the condition for directionality, whereas an unwanted echo may be received but is discarded in software or circuitry if does not meet the condition. In many cases this will be more accurate than mechanical or physical acoustic blocking of unwanted echoes. Further, the technique has the potential to allow a variety of sensing areas to be readily configured.

In embodiments, the directional information determined for the echo is combined with a measurement of the range from which it has been received, e.g. measured in terms of time-of- flight if the sensor also knows the time the original wave was emitted. The signal processing module can then apply a limit on the range from which an echo will trigger a positive presence result. This way both the directionality and the extent of the sensing region can be shaped as desired. The directionality may be implemented by making the range threshold a function of direction. The direction may be measured using an angle-of- arrival estimation, and the range threshold may be a function of received angle.

This way it is possible to define practically any shape of detection area that is required. For example, when the effective detection "beam" formed by the sensing region is projected onto a flat surface such as a floor or desk, this means the detection area is not constrained to being a circular or elliptical area, but could instead be square or rectangular like a room, or an L, T or cross shape like a section of corridor. Nor is the sensing region or area constrained to being defined by obstacles in the space. In further embodiments, the sensing region may be configured at least in part by a user, e.g. at the commissioning stage or even in day-to-day use. For example the sensor may be provided with mechanically variable switches (e.g. slide switches) to set the angle and range, or a software interface by which the region can be programmed. Alternatively, rather than adjusting the sensitivity or specifying the range and angle directly, the user may specify the desired area and the signal processing module works out the time-of- flight and angle settings to apply to create that area. In one embodiment, a user may even program the region by disposing him or herself about a plurality of points of the sensing area on the floor, e.g. walking along the perimeter or a boundary of the area.

According to an exemplary application, there may be provided a lighting system comprising: a signal processing module in accordance with any of the features disclosed herein, the receiver arranged to emit the signal, a transmitter arranged to transmit the signal, a flat surface (such as a floor or desk), and one or more lighting devices arranged to illuminate this surface. The effect of the directionality of the sensing region may be to create a non-circular, non-elliptical sensing area projected onto the flat surface (or more generally an area that is not based on a conic section). The sensing logic is arranged to sense a being or other object upon this surface, and the signal processing module further comprises a controller arranged to control the one or more lighting devices based on the sensing result.

According to yet another aspect disclosed herein, there may be provided a computer-program product for performing sensing based on echoes of an emitted signal. The computer program product comprises code embodied on a computer-readable medium and being configured so as when executed on a processor to perform operations of the signal processing module.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present disclosure and to show how embodiments may be put into effect, reference is made to the accompanying drawings in which:

Fig. 1 is a schematic illustration of a sensing region within a space,

Fig. 2 is a schematic block diagram of a lighting device with sensor,

Fig. 3 is another schematic illustration of a sensing region within a space, Fig. 4 is a schematic block diagram of a receiver for use in a sensor,

Fig. 5 is a schematic illustration of a sensing area,

Fig. 6 schematically illustrates some further example sensing areas, Fig, 7 schematically illustrates another example sensing area, Fig, 8 schematically illustrates yet another example sensing area, and

Fig 9 is a schematic flow chart of a sensing method.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The following relates generally to presence detection, e.g. for energy saving in lighting systems. Embodiments provide improved presence detection using ultrasonic (US) sensors instead of the conventional passive infrared (PIR) sensors.

In a recent development, an ultrasound transmitter can be used in combination with a receiver comprising an array of microphones. This allows the angle of arrival (AoA) to be determined by measuring phase differences between the instances of the echoed signal as received at the different receiver elements of the array (the different microphones). The ultrasound sensor disclosed below combines this with range information such as time-of- flight (ToF) to determine whether motion is inside or outside a desired detection area. Thus the sensor can be configured to detect motion only within a specified sensing area, which may be square, L-shaped or practically any desired shape.

There may also be provided a user interface via which an installer can configure the detection area as desired. The user interface may take the form of physical switches and/or a software interface.

Figures 1 and 3 illustrate an example of an environment in which embodiments disclosed herein may be employed.

The environment comprises an indoor or outdoor space 2 such as an office space, an interior space within a home, a laboratory, a marquee, garden or park, etc. The following will be described in terms of an office but it will be appreciated that this need not be limiting. The space 2 comprises a surface 10 upon which presence of a being or other object is to be detected, typically a flat surface. The type of being that of interest is typically a person (human), though it is not necessary that the sensor distinguishes between humans and other beings. The surface 10 may be an underfoot surface such as the floor, the ground or a platform or gangway or the like. Alternatively the surface could be a desk, table, worktop, workbench or the like. In most applications the surface is a lower surface, though this does not necessarily have to be the case. In the example of an office discussed below the lower surface 10 is the floor, but again it will be understood this does not have to be limiting. The space 2 comprises a sensor 6 mounted or otherwise disposed at a location 8 so as to face the surface 10. In the illustrative example, the sensor 6 is mounted on the ceiling 8 of the office 2 so as to sense presence of someone walking on the floor 10.

As shown schematically in Figure 2, the sensor 6 comprises a signal processing module 16, and an ultrasound transceiver 18 comprising an ultrasound transmitter 20 and an ultrasound receiver 22 coupled to the signal processing module 16. The signal processing module may be implemented in code (software) stored on a memory comprising one or more storage media, and arranged for execution on a processor comprising on or more processing units. The code is configured so as when fetched from the memory and executed on the processor to perform operations in line with embodiments discussed below.

Alternatively it is not excluded that some or all of the signal processing module 15 is implemented in dedicated hardware circuitry, or configurable hardware circuitry like an FPGA. In embodiments the signal processing module 16, transmitter 20 and receiver 22 are integrated together into the same unit (e.g. same housing), though this is not necessarily the case. For example in an alternative arrangement the transmitter 20 could be located at a different location than the receiver 22, e.g. one transmitter serving multiple receivers. Also the signal processing module 16 (or some elements of it) could be remote from the transmitter 20 and/or receiver 22, e.g. as part of a central controller processing signals from multiple receivers.

The transmitter 20 is arranged to emit an ultrasound signal. In embodiments the signal is emitted in the form of a series of pulses of a certain frequency (e.g. 40kHz), but it could also be a continuous wave identifiable by its frequency (e.g. again 40kHz). In embodiments a pulsed signal is preferred in order to be able to determine time of flight. The transceiver 18 also comprises a receiver 22 for receiving back echoes of the transmitted signal, e.g. of the transmitted pulses. Presence can be sensed based on detection of the pulses (or more generally signal) being echoed (reflected) from a being or other object, e.g. by detecting motion based on a Doppler shift between the transmitted signal and received echo. Techniques for sensing of presence based on reflected echoes will in themselves be familiar to a person skilled in the art.

Referring to Figure 1, the direction along which the sensor 6 is pointed defines an axis 11, and a plane perpendicular to that axis. In the case of a room such as an office with the sensor 6 mounted on the ceiling 8 pointing downwards, the axis 11 is vertical and the plane is a horizontal surface such as the floor or a desktop. A conventional ultrasound sensor 6 would detect any echoes arriving back at the sensor within a certain fixed, maximum angle between the echo's direction of travel and the axis 11 of the sensor 6 (i.e. within a maximum polar angle Θ relative to the axis 11 of the sensor 6, where the axis 11 is considered the zenith of a spherical polar coordinate system). This angle may be defined by the opening angle of the sensor 6. Alternatively in

embodiments it is possible to detect beyond this angle when relying on multipath. In this case, the object may be outside the opening angle of the sensor, but because the sound is reflected from objects inside the opening angle it is possible to create an acoustic path that can be used for detections.

In the plane 10 perpendicular to the axis 11, the sensor may indiscriminately detect any echoes in a full 2π radian circle symmetrical about that axis (i.e. arriving from any azimuth angle ø relative to the axis 11 of the sensor 6). Thus there is defined a sensing region 12 in which the sensor 6 will detect presence. The sensing region 12 may also be referred to as a detection "beam" (though it is a beam in which signals are received back, not a transmitted beam). In the conventional situation as described in relation to Figure 1, the sensing region or beam 12 takes the form of a cone. In a plane of interest 10 (e.g. the floor), the projection of the beam 12 forms a detection area 14. Where the plane is perpendicular to the axis 11, the detection area 14 is circular. If the sensor 6 is pointed at an angle other than perpendicular, the detection area 14 is another conic section - i.e. an ellipse (or a parabola or hyperbola if the surface 10 only partially cuts the detection beam, e.g. due to an obstacle like a wall).

Referring to Figures 3, embodiments disclosed herein provide a sensor 6 whose detection region 12' can be adjusted to cover only a desired detection area 14', without just simply reducing sensitivity of the sensor, and in a way that is not restricted to the conic section of a detection beam that is symmetrical about its axis. I.e. the detection beam or region 12' need not be circular in cross section perpendicular to the direction of the beam (direction of the sensor). In embodiments, it is possible to create a modified sensing region 12' which will form any desired sensing area 14' when projected onto a surface 10, and this area need not necessarily be a circle when projected onto a flat surface. Nor need the sensing area 14' necessarily take the form of an ellipse, nor a shape with a parabolic or hyperbolic edge (though a user could happen to choose these shapes if desired). Instead, the modified sensing region 12' and sensing area 14' can be given a directional dependency about the axis of the sensor 6 (axis of the detection beam) that means the shape of the sensing region 12' and area 14' are not necessarily uniform about that axis. Figure 3 shows an example in which the overall range of the modified sensing area 14' is reduced relative to the unmodified sensing range of Figure 1, and only covers a certain angles about the axis of the sensor 6 fall within the modified sensing area 14', e.g. a certain span or interval of angles. That is, the sensor 6 only returns a positive sensing result for echoes arriving from certain azimuth angles ø relative to the axis 11 of the sensor 6, but not others. Echoes from the defined interval of angles are excluded. Put another way, the modified sensing area 14' may be referred to as pie shaped. However other shapes are also possible, as will be discussed shortly.

To implement this, the signal processing module comprises sensing logic 11 and an event filter 13. The sensing logic 11 is arranged to perform the raw sensing involved in receiving echoes of the signal in question, e.g. the ultrasound pulses. The event filter 13 is configured to then process the received pulses to detect their direction of arrival and the distance from which they were received, and, based on these measured variables, to disregard any pulses that do not fall within the desired sensing region or area.

Figure 4 shows an example of a receiver 22 for use in implementing a directional dependency in the shape of the detection region 12' or area 14'. The receiver 22 in conjunction with the event filter 13 of the signal processing module 16 uses angle-of- arrival (AoA) estimation to determine the direction from which a given echo has arrived back at the sensor 6. To this end, the receiver comprises an array of receiver elements 24 (at least two and in embodiments more). In embodiments a two dimensional array is used, e.g. an

NxM grid, to allow the angle of arrival to be measured through a full 2π radians (360 degree). A four-by-four array of elements 24_1;1...24_4,4 is shown by way of example in Figure 4. In an ultrasound sensor 6, each receiver element 24_1;1...24₄,₄ comprises a separate microphone. Because the receiver elements 241,1 . . ·24_4ι4 are spaced apart, the same instance of a given echo will arrive at each with a slightly different time and phase. Figure 4 illustrates the same echo arriving at each of the receiver elements 24i_,i ...24_4,4 with a different respective phase Ψι,ι ... Ψ₄,₄. By comparing the timing and/or phase difference between the different instances of the same signal as received at each of the different receiver elements 24_1;1...24_4,4, the event filter 13 is able to determine the direction from which the echo is received at the sensor 6. The principles of AoA estimation will in themselves be known to a person skilled in the art. In embodiments the determined direction is resolved to an angle ø (azimuth angle) in the plane 10 of the detection area 14', i.e. the plane of the surface upon which presence is to be detected. Figure 5 illustrates how the measurement of this angle ø may be used to create a modified sensing area 14' in accordance with embodiments disclosed herein. As well as the angle ø, the event filter 13 is also configured to measure the range of the echo. That is, the distance between the sensor 6 and the point from which the signal was echoed. This may be determined in terms of time-of- flight (ToF), assuming the wave travels at substantially constant speed in the medium (speed of sound in air of ultrasound). Where the transmitter 20 is placed at substantially the same location as the receiver 22, the distance is half the time-of- flight multiplied by the speed; or if the transmitter is placed elsewhere, the signal processing module may also take into account the relative geometry of the transmitter 20, receiver 22 and direction of the echo. In embodiments the event filter 13 may combine the distance travelled with the direction of arrival to resolve the distance into a range in the plane 10 of the sensing area 14', so into a radius relative to the axis of the sensor 6 (axis of the detection beam) in the plane 10. Where the plane 10 is a horizontal surface such as the floor, this radius is the horizontal range.

The event filter 13 may be configured to then apply a threshold to the range from which the echoes are received, in this case a threshold T on the range in the sensing plane 10. The threshold is a function of direction from which the echoes are been received at the sensor 6, in this case a function T(o) of the angle of arrival projected into the relevant plane 10 (e.g. floor). When an echo arrives at the receiver 22 of the sensor 6, the event filter 13 detects its direction and range and compares its range with the threshold T(o) as evaluated at that respective direction. On condition that the detected range is within the threshold for that angle, the event filter 13 issues a positive sensing result. Otherwise if the detected range is beyond the threshold for that angle, the echo is discarded or ignored, i.e. does not give rise to a positive sensing result.

Thus potentially all echoes that would have been received in the example of

Figure 1 are received by the sensing logic 11, but the sensing area 14' is created in the code or circuitry of the signal processing module 16 by processing the received echoes and excluding those that are outside the desired area 14' or region 12'.

As an example Figure 5 illustrates a square sensing area 14', but Figure 6 illustrates some other examples. E.g. the sensing area 14' could be made pie-shaped, square or rectangular, L-shaped, cross-shaped or T-shaped. The function T(o) could be an analytical function, for example an equation for a square in polar coordinates; or could be hard-coded or hard-wired or implemented using a look-up, for example based on a predetermined mapping between radius and the points on the perimeter of the square or other shape (e.g. determined by making empirical measurements at the design or installation stage).

Further, the range threshold T(o) may comprise a continuously variable function (to give a shape with smooth edges), and/or a function having a step (e.g. a pie shape) or a step in its gradient (e.g. a square), etc. For example for a pie-shaped sensing area 14', the range threshold is zero for some angles and a constant non-zero value for others.

In an example application of the teachings disclosed herein, the space 2 comprises one or more lighting devices 4 in the form of one or more luminaires operable to emit light. The sensor 6 is coupled to the luminaire(s) 4, and its signal processing module 16 comprises a controller 15 arranged to control the light to be turned on or off, or dimmed, in dependence on presence being sensed. The luminaire(s) may be arranged to be controlled directly by the sensing results reported by the event filter 13, or by the event filter 13 reporting sensing results to a separate control unit, e.g. a central controller responsible for controlling a plurality of lights.

In embodiments, the shaping of the sensing area 14' allows the sensing area

14' to be adapted to fit to the layout of the space 2 in question, e.g. to the floor-plan of an indoor space such as an office. For example, a rectangular, L-shaped, T-shaped or cross- shaped sensing area 14' may be arranged to cover a correspondingly shaped section of corridor; or a square or rectangular shape may be used to cover a correspondingly shaped office or only a desired section of an office. A pie-shaped area 14' could be used to fit around corners or other features.

For instance, the space 2 may comprise a cellular office space in which different sub-spaces are defined by partitions having poor sound-insulating properties, e.g. defining a plurality of cubicles. Using embodiments of the techniques disclosed herein, the sensing area can be confined to only a desired cubicle or corridor; whereas a conventional sensor's circular sensing area (as illustrated in Figure 1) would extend thought walls and trigger sensing results from an adjacent room or corridor. Even in situations with good sound-insulating walls, open doors or windows may cause unwanted sensing results to be triggered when a user passes by outside the desired area.

In embodiments, an installer will be enabled to easily configure the sensor 6 for the room or environment in question. To this end the signal processing module 16 is provided with a user interface 17 via which the user can specify one or more variables which at least partially define the sensing area 14' or more generally sensing region 12'. In embodiments, the user interface 17 may comprise a mechanically variable switch, e.g. a continuously variable mechanical switch like a slider or dial. For instance these may be provided on the exterior casing of the sensor 6, or mounted on the wall at a convenient height. Alternatively or additionally, the user interface may comprise a digital communications interface, e.g. a software interface.

For instance, for a 1 -dimensional area (having one degree of freedom, e.g. along a corridor) the sensor 6 may be equipped with two mechanical sliders or dials, or the signal processing module 16 may have two software parameters that can be configured. One slider, dial or parameter would be for range, e.g. in meters or yards; and one would be for angle, e.g. in radians or degrees. As an example, the detection area 14' may take the form of an acute pie-shaped wedge, or two symmetrical acute wedges arranged to face in opposite directions either way along a corridor. The two dials or slides may then vary the radius R and width a of the wedge. See Figure 7.

For a 2D area, the sensor may allow for configuration in two axes. This may be controlled using two mechanical sliders, plus a means to select axis; and/or by four software parameters. For instance the detection area 14' may take the form of an acute pie- shaped wedge with a central axis having a variable direction β relative to the sensor. See Figure 8.

Alternatively for a 2D area, more software parameters may be made available to allow for more varied detection areas (irregular shapes).

In some advantageous embodiments, the user does not have to explicitly specify the angle and range parameters of the desired sensing area 14', but rather can specify the desired area in terms of the desired area itself. In this case the user interface 17 may comprises a digital interface such as a software interface. The user interface 17 accepts a user specification defined in some way in terms of a desired area, not the range and angle parameters like R, a and β or the angular function T(o) required to create that area. For example this may be defined by the user drawing the desired area 14' on a screen of a computer terminal, or scanning in a paper drawing, or by the user walking around a boundary of the desired area, or standing at different points in the desired area. The event filter 13 then works backwards to determine the parameters or function T(o) that will results in that area. For example this may be achieved by generating a look-up table of a suitable number of points around a boundary of the area 14', or by a shape recognition algorithm.

In one embodiment of this, there is provided a configuration mode of the sensor 6 in which an installer can walk to different parts of the space 2 to appropriately configure the sensor 6, e.g. by walk around the perimeter of a desired detection area in order. In the configuration mode, the signal processing module 16 uses the sensor 6 to detect the presence of the installing user at a plurality of different times when that user is disposed at different locations within the space 2. This could be triggered for example periodically, or by detecting motion of the user, or by a manual trigger from a remote control of the user. The signal processing module 16 detects the point at which the user is located each time, then uses these points to determine the desired sensing area 14'. E.g. this could be a perimeter bounded by joining the different points, or a corridor- wide rectangle extending length- ways between two points.

In further embodiments, the signal processing module 16 of the sensor 6 can also measure mounting height, based on the strongest echo coming from hard table surface. The event filter 13 will then take this information into account to determine the optimal sensing duration (time of flight), and allowed angles so the installer does not have to calculate this, and can just configure the sensing area as intended on the sensing surface.

As discussed, the sensor can then optimize or otherwise modify the following parameters.

Sensing duration: when using an active pulse based ultrasound sensor, the sensing distance can determined by the time it takes for an ultrasound wave to be emitted , reach the end of the sensing area and let the echo return to the sensor (time of flight).

- Angle of arrival: when able to sense angular information, a sensor can use this information to check against the desired angles.

By combining both parameters, one or more of the following may be achieved.

Fewer false triggers resulting from presence outside of the sensing area of interest (e.g. a hallway)

- very accurate detection area configuration, and/or

asymmetric or irregular detection areas can be configured.

Figure 9 provides a flow chart showing steps that may be performed by the signal event filter 13 of the sensor 6. At step S 10 the user has requests a reduced sensing area. At step S20, the sensor determines its height from floor (as ceiling height will also influence sensing area on floor level). At step S30, the sensor reduces measurement time according to requested sensing area taking into account ceiling height. At step S40 the sensor monitors for any motion being sensed within the desired detection area by determining whether detected motions originate from the desired angles. If so, at step S50 the sensor reports presence. If not, at step S60 the sensor refrains from reporting presence (either does nothing or issues a negative report).

It will be appreciated the above embodiments have been described only by way of example.

For instance, sensing presence is not limited to sensing motion, nor sensing a human. Generally presence sensing techniques are available for sensing either the motion or the existence of any being (whether human or other living creature) or other animate in inanimate object. Further, the disclosed techniques can be used in other sensing applications, other than for controlling a lighting system.

In further embodiments, other ways of detecting direction and/or range may be employed. For example to detect direction of arrival, the receiver 22 could comprise a plurality of directional receiver elements each facing in a different direction, e.g. one per direction that can be detected. Alternatively or additionally, range could also be measured in other terms, e.g. based on the power received back at the receiver 22 given knowledge of the power with which it was emitted by the transmitter 20. Further, other variants for defining a detection region 12' could be employed. For example, rather than defining a two-dimensional sensing area in terms of the range and angle projected onto a two-dimensional surface or plane, a threshold may be applied to the range in terms of the full three dimensional distance from the sensor (e.g. the radius p in a spherical polar coordinate system), and the threshold may be a function of the direction in three dimensions (e.g. both polar angle Θ and azimuth angle ø in a spherical polar coordinate system). This way any desired three-dimensional sensing region may be created. Generally the shaping of a sensing region may refer to shaping the region so as to create a desired sensing area when the region is projected into a plane or surface, or shaping to create a desired three-dimensional region.

Where it is said above that a value is within a limit or threshold (or the like), this covers the options of either a "less than" type operation or a "less than or equal" to type operation. Similarly, if it is said that a value is beyond or exceeds a limit or threshold (or the like), this covers the options of either a "more than" or a "more than or equal to" type operation. Further, where it is a said that the signal processing module reports a sensing result, this may mean outputting to a user, to a control element such as the controller of a lighting device, and/or issuing an internal signal to any other software or hardware element (e.g. the report could be subject to further conditions, filtering or other processing before it is used to control any device or output any information). Further, the teachings above to not have to be limited to ultrasound sensing, but could be extended to any active sensing technique based on the emission of any signal (e.g. mechanical or electromagnetic radiation) and receiving back echoes of such a signal. Where the sensor is an ultrasound sensor, the microphone receiver elements 24 may or may not be dedicated to receiving just ultrasound. In embodiments, besides measuring the ultrasonic content, these microphones can also be used for receiving audible sound.

Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. A single processor or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measured cannot be used to advantage. A computer program may be stored/distributed on a suitable medium, such as an optical storage medium or a solid-state medium supplied together with or as part of other hardware, but may also be distributed in other forms, such as via the Internet or other wired or wireless telecommunication systems. Any reference signs in the claims should not be construed as limiting the scope.

Claims

CLAIMS:

1. A signal processing module (16) for use with a receiver (22) for receiving echoes of an emitted signal, the signal processing module comprising:

sensing logic (11) for performing sensing based on said echoes; and an event filter (13) configured to detect a respective direction from which each of said echoes is received at the receiver, and based thereon to limit said sensing to a sensing region (12') having a directional dependency relative to the receiver (22), whereby a sensing result is reported in dependence on the respective direction detected for one or more of said echoes being consistent with the directional dependency of the sensing region (12').

2. The signal processing module of claim 1, wherein the event filter (13) is further configured to detect a range from which each of said echoes is received, and the sensing region (12') has a range limit relative to the receiver, the sensing result being reported in dependence on the detected range of the one or more echoes being within the range limit.

3. The signal processing module of claim 2, wherein the directional dependency comprises the range limit being a function of the direction, the sensing result being reported in dependence on the detected range of the one or more echoes being within the range limit for the respective direction that is detected.

4. The signal processing module of claim 1, 2 or 3, wherein the event filter (13) is configured to detect the direction by detecting a respective angle at which each of the echoes is received at the receiver (22), and the directional dependency comprises an angular dependency, the sensing result being reported in dependence on the detected angle for the one or more echoes being consistent with the angular dependency.

5. The signal processing module of claim 4, wherein the angular dependency comprises the range limit being a function of the angle, the sensing result being reported in dependence on the detected range of the one or more echoes being within the range limit for the respective angle that is detected.

6. The signal processing module of claim 4 or 5, wherein the receiver (22) comprises an array of two or more receiver elements (24), and the event filter (13) is configured to detect the angle by measuring time and/or phase differences between instances of the echo as received by each of the receiver elements (24).

7. The signal processing module of any preceding claim, wherein the event filter (13) is configured to measure a mounting height of the receiver (22) relative to a surface (10), and to configure the sensing region (12') in dependence on the mounting height.

8. The signal processing module of any preceding claim, comprising an input (17) for receiving a user input at least partially defining the sensing region (12'), wherein the event filter (13) is configured to apply the sensing region in accordance with the user input.

9. The signal processing module of claim 8, wherein the sensing region (12') corresponds to a sensing area (14') on an underfoot surface (10), and said input (17) comprises a mode of the signal processing module (16) configured to receive the user input by detecting the user disposing him or herself at a plurality of points at least partially defining the sensing area (14').

10. The signal processing module of claim 6 and 8, wherein the input (17) comprises a mechanically variable switch for varying the angle and a mechanically variable switch for varying the range.

11. The sensor of any preceding claim, wherein the sensing region (12') will form an area (14') other than a conical section when projected onto a flat surface.

12 The sensor of claim 11, wherein the detection area (14') has at least one straight edge.

13. The sensor of claim 12, wherein the detection area (14') comprises a square or rectangular area, an L-shaped area, a T-shaped area, a cross-shaped area, or a pie-shaped area.

14. A lighting system comprising:

the signal processing module (16) according to any preceding claim;

the receiver (20) arranged to receive the echoes of the emitted signal;

a transmitter (22) arranged to emit said signal;

a flat surface (10); and

one or more lighting devices (4) arranged to illuminate said surface (10); wherein the sensing region (12') corresponds to a sensing area (14') other than a conical section when projected onto the flat surface (10); and

wherein the sensing logic (11) is arranged to sense a being or other object upon said surface (10), and the signal processing module (16) further comprises a controller (15) arranged to control the one or more lighting devices (4) based on said sensing result.

15. Computer program product for performing sensing based on echoes of an emitted signal, the computer program product comprising code embodied on a computer- readable medium and being configured so as when executed on a processor to perform operations of:

detecting a respective direction from which each of said echoes is received at a receiver (22); and

based thereon, applying a sensing region (12') having a directional dependency relative to the receiver (22), whereby a sensing result is reported in dependence on the respective direction detected for one or more of said echoes being consistent with the directional dependency of the sensing region (12').