Motion detection and lighting means * * ** * 1 * *
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The present invention relates to the field of motion detection and of motion sensors or presence sensors. The invention particularly relates to a method for detecting motion and to a 10 device and system for performing such detection.
The use of a motion sensor in combination with lighting means is already known in the state of the art. So-called motion or presence sensors actually react on motion and are connected to lighting means in such a way that light is turned on when motion is detected by the motion sensor. On the other hand, light is turned off after a fixed, user configured, delay time during which no motion is detected.
The task of the motion sensor is to detect and signal a motion in order to control the lighting means according to this signaled motion. Thereby the sensor detects a motion in a known manner as soon as a motion signal is above a threshold, said motion signal reflecting the amount or intensity of motion within the area covered by the sensor. If the motion signal or its amplitude is below the threshold, no motion is detected. On the other hand, a motion signal above said threshold will trigger a motion detection and a corresponding control of the lighting means. It is known that this threshold can be 3o configured so as to achieve a desired sensitivity of the motion sensor.
The behaviour of lighting means controlled on the basis of a motion sensor thus depends on the sensitivity of the motion sensor and on the time delay after which the lighting means can be turned off. It is known to configure the sensitivity and the time delay with potentiometers, dip-switches or with proprietary configuration tools like e.g. IR remote controls.
This known configuration is problematic in that potentiometers 5 require the sensor to be accessible, and IR remote controls require the sensor to be visible. Further on, both solutions require additional hardware components.
A further drawback is that the choice of sensitivity and time 10 delay is left to the installer, which means additional work for the installer. Such a choice is rather difficult and cannot be accurate. It can be repeatable only with coarse settings.
The settings also depend on the environment in which the motion sensor is installed. Long time delays and high sensitivity are e.g. necessary in applications where occupants will spend long time in a room without generating large motion, like in an office. On the other hand, short delay time is necessary in corridors where lights are needed only when someone is passing by. That is, it is disadvantageous that each application requires proper, different configuration.
In any case such a known motion sensor will be triggered by a person leaving the monitored area. This is disadvantageous in that the connected lighting means are then switched on for a given period of time even if nobody is present in the area, thereby causing a waste of energy.
The present invention proposes an improved method for avoiding 3o the disadvantages mentioned above.
According to an aspect of the invention, it is proposed a method for identifying a presence state or a non-presence state of people in an area covered by a motion sensor. The motion sensor changes autonomously its behaviour depending on ongoing motion sensing. * ** * * * O00 * * *
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* * * os * * ** * According to a further aspect of the invention, it is proposed a motion sensor for identifying a presence state or a non-presence state of people in an area covered by a motion sensor. The motion sensor is adapted to change autonomously its behaviour depending on ongoing motion sensing.
* * * This implies for example that it is not necessary for an installer to configure the detection and the motion sensor. This is an improvement vis-a-vis sensors of the state of the * . * *** io art that need to be configured in the field since the user that configures a sensor has no way to determine what the optimal settings are and for this operation the sensor has to be accessible or even visible. The autonomous behaviour change also eliminates the disadvantage that with state of the art * 15 sensors the lights always remain on for a time as long as the timer delay after the occupants have gone away. *
The behaviour of the motion sensor can depend on the * * instantaneous value of a motion signal, said motion signal * 20 being measured by the motion sensor and reflecting the amount O0 0 of motion in the covered area, and on an average value of the * * * * 00 motion signal. *
The motion sensor can detect a large instantaneous motion on the basis of the instantaneous value of the motion signal. It can detect a small average mction on the basis of the average motion signal. Alternatively, it can detect a large average motion on the basis of the average motion signal. The motion sensor can identify a presence state or a non-presence state 3o depending on the detected large instantaneous motion and at least one of the detected small average motion and the detected large average motion.
The motion sensor can change autonomously its behaviour depending on the detection of large instantaneous motion, small average motion and large average motion.
The large instantaneous motion can be detected when the instantaneous motion signal is above a first threshold. The small average motion can be detected when the average motion signal is below a second threshold. The large average motion can be detected when the average motion signal is above a third threshold. * * * * * * *** * **** * * **** * * * * * * . * **
A counter, preferably initialized at the value zero, can be increased by a value z when a large instantaneous motion is lo detected. The counter can be decreased by a value x when a small average motion is detected. The counter can be increased by a value y when a large average motion is detected.
The presence state can be identified when the counter reaches an upper threshold and the non-presence state can be identified when the counter reaches the value zero.
The upper threshold can correspond to the value z. The motion sensor can change autonomously its behaviour by modifying at least one of the first threshold, the second threshold, or the third threshold. Alternatively, the motion sensor can change autonomously its behaviour by modifying at least one of the value z, the value x and the value y.
Alternatively, the motion sensor can change autonomously its behaviour by modifying at Least one of the first threshold, the second threshold, the third threshold, the value z, the value x and the value y.
3o The behaviour of the motion sensor can be adapted by decreasing the value z and/or by increasing the value x in the case that the counter reaches zero after a detected large instantaneous motion followed by a succession of detected small average motions. Preferably, the counter has been preferably initialized to zero before the detection of the large instantaneous motion.
The behaviour of the motion sensor can be adapted by decreasing the first threshold in case the counter reaches zero after a detection of a large instantaneous motion followed by a successive detection of small and/or large average motions.
Preferably, the counter has been preferably initialized to zero before the detection of the large instantaneous motion. * ** * * . *** * * *
* * **** * * * ** * ** * * *tp The behaviour of the motion sensor can be adapted by decreasing the first threshold in case the counter reaches the value z lo after a successive detection of small and/or large average motions without any large instantaneous motion. Preferably, the counter has been preferably initialized to zero before the detection of the large instantaneous motion.
The behaviour of the motion sensor can be adapted by increasing the second threshold in case a small average motion has not been detected since a predetermined time, e.g. since more than one day.
A light source coupled with the motion sensor can be turned on if the presence state is identified, and the light source can be turned off if the non-presence state is identified.
According to a further aspect of the invention, it is proposed a system comprising such a motion sensor, and controlling means connected to the motion sensor for controlling lighting means. The controlling means is adapted to control the lighting means depending on a presence state or a non-presence state identified by a motion sensor.
The controlling means can be adapted to switch on the lighting means if the presence state is detected and to switch it off if the non-presence state is detected.
The invention will be explained in the followings together with Figures.
Fig. 1 shows a schematic representation of a system according to the present invention, Fig. 2 shows a schematic representation of a motion sensor 5 according to the present invention, Fig. 3a shows an embodiment for event detection according to the present invention, lo Fig. 3b shows an embodiment for event detection according to the present invention, Fig. 3c shows an embodiment for event detection according to the present invention. * .. * * *
*** Fig. 1 shows a schematic representation of a system 10 * according to the present invention comprising a motion sensor
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SOO source or lighting means 4. The light source 4 shown in Fig. 1 * * 20 is representative of any kind of light source and can e.g. correspond to an LED in form of an organic or inorganic light * . * o0 emitting diode, or to a gas discharge lamp. Instead of one * *** * light source 4, the system may comprise a plurality of light sources that can be connected in series, in parallel or 25 according to a more complex combined serial and parallel arrangement.
The light source 4 is connected to the control device 2 by means of a dedicated connection i.e. dedicated wires 3. The 3o control device 2 can also be referred to as an operating device or a ballast and has the function of supplying the light source 4 with electrical energy, i.e. with current. The control device 2 is connected to mains power supply 5 and is adapted to transfer energy to the light source 4 in a known manner. In order to operate the light source 4, the control device 2 can be in the form of a switched-mode power supply and can comprise a switched converter for generating a desired voltage for the or motion detector 1, a control device 2 as well as a light light source 4 and a desired current through the light source 4. The switched converter can be a buck converter, a boost converter, a flyback converter, or e.g. a resonance converter. * .. * * * * * * * * * . * * * ** * **
The motion sensor 1 is adapted to detect moving objects and particularly people. The detection is performed in a given area that is covered by the motion sensor 1, said covered area being the field of view of the sensor. Advantageously, the covered area corresponds to the zone illuminated by the light source 4.
Alternatively, the covered area comprises said illuminated zone or is comprised in said illuminated zone. The motion sensor 1 is particularly adapted to sense a change in position of an object or a person within said covered area. The method used by the motion sensor 1 to detect motion is known in the art and can be based on a technology like e.g. passive infrared (PIR) motion detection, microwave, radar, ultrasonic or tomographic motion detection, or video camera motion detection.
The control device 2 comprises an input connection D1, D2 to connect the motion sensor 1. The motion sensor 1 is connected to the mains power supply 5 as well as to the control device 2, such that it can apply to the input connection D1, D2 of the control device 2 a coded voltage that transmits information regarding a detected motion or presence in the covered area.
The voltage applied to the input connection Dl, D2 is coded in that it can indicate to the control device 2 whether or not a motion has been detected, i.e. whether or not a presence has been identified. E.g. if no motion or no presence is detected, the motion sensor 1 can apply a zero voltage to said input D1, 3o D2, while a voltage of a defined amplitude can be applied when a motion or a presence is detected. E.g. the voltage applied in case of a detected motion or detected presence can be the mains supply voltage. The voltage applied to the input connection D1, D2 can be coded in a different way.
The coded voltage applied at the input connection D1, D2 is decoded by the control device 2. After decoding, the control device 2 controls the light scurce 4 depending on the decoded information. E.g. the light scurce 4 is turned on if the decoded information relates to a presence state P, i.e. when the presence of people is detected by the motion sensor 1, and is turned off if the decoded information indicates a no presence state NP. In case of a no presence state, i.e. in case the motion sensor 1 has identified that nobody is present in the covered area, the light source can alternatively be dimmed. * * *
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* * * * * * * * * * lo According to the present invention, the presence state P and the non-presence state NP related to the presence of people in the area covered by the motion sensor 1 are detected autonomously by the motion sensor.
The behaviour of the motion sensor 1, i.e. particularly the detection of the presence or no presence state, may change depending on ongoing motion sensing of the motion sensor 1. The detection of the presence state or the non-presence state may depend on the history of the motion sensing.
The motion sensor 1 is adapted to measure a signal, also called motion signal, reflecting the amount or the intensity of motion in the covered area. Such signal, and particularly the generation of such signal, is known in the art. The motion signal is generated by a dedicated sensing unit of the motion sensor 1, said sensing unit being based e.g. on passive infrared (PIR) motion detection, microwave, radar, ultrasonic or tomographic motion detection, or video camera motion detection. If required, the motion signal can be rectified 3o and/or amplified as known in the state of the art.
Fig. 2 is a schematic representation of a motion sensor 1 according to an embodiment of the invention.
The motion sensor 1 comprises optical means 20 like a lens for defining the area 21 covered by the motion sensor 1 in which motion can be detected. A sensor 22 generates the motion signal according to e.g. a passive infrared (PIR) motion technology. Other known methods for generating a motion signal reflecting the amount of motion in the ccvered area 21 can be used. The sensor 22 is coupled to the optical means 20. An optional processing unit 23 can rectify and/or amplify the generated motion signal. * **
* * lb ** * * * *** * * ** * * * * * * * * * * * * * ** * The motion sensor 1 further comprises an evaluation unit 24 for evaluating the generated motion signal. The task of the evaluation unit 24, and particularly of a decision unit 27 of said evaluation unit 24, is to determine whether or not, based on the motion signal, people are present in the covered area 21. The decision unit 27 accordingly detects the above-mentioned presence state P or no presence state NP, and generates the coded voltage for the control device 2 depending on the detection of the presence state P or no presence state NP.
According to an embodiment of the invention, the evaluation unit 24 of the motion sensor 1 is adapted to use the motion signal generated by the sensor 22 and optionally processed by the processing unit 23 in order to perform an event classification.
A first event that can be detected is a large instantaneous motion A. The evaluation unit 24 thereby preferably comprises comparing means like a comparator 25 that compares the instantaneous motion signal, i.e. for example the amplitude of said instantaneous motion sicnal, with a threshold value M that 3o can be stored in a storage unit 26. The output of the comparator 25 is supplied to the decision unit 27 so that the decision unit 27 is able to detect a first event A on the basis of the output of the comparator 25 when the instantaneous motion signal is above the threshold value M. This first event A corresponds to a large instantaneous motion within in the area 21 covered by the motion sensor 1. The initial value of the threshold M that is stored in the storage unit 26 can be a predetermined value. If the motion signal, i.e. the instantaneous value of the motion signal, is high enough, a first event A is detected. Preferably, a first event A is detected if the amplitude of the instantaneous motion signal is close to a maximum value of the motion signal.
According to the present invention, this threshold value M can be modified autonomously by the motion sensor 1 to adapt to the 10 environment of the motion sensor 1. * **
* * * *** eeeeee * * * * * * * * ** * * * * * * * * * ** * * * * * In reaction of such a large motion, preferably in reaction to such a high value of the instantaneous motion signal, the system and particularly the motion sensor understands that at least one person is present in the area covered by the motion sensor 1 and that the light shall be turned on. Therefore in case the first event A is detected, the decision unit 24 preferably generates a coded voltage that is a command to turn on the light source 4. The coded voltage is received by the control device 2 through the input connection DI, D2. The control device correspondingly interprets the coded voltage as a command to turn on the light source 4 and turns on said light source 4.
A second event that can be detected is a small average motion B. The evaluation unit 24 thereby preferably comprises averaging means, for example in form of an integrator 28, adapted to generate an average value of the motion signal. The output of the integrator 28 is applied to a comparator 29 that 3o compares the average motion signal, i.e. for example the average value of the motion signal amplitude, with a threshold value m that can be stored in a storage unit 30. The output of the comparator 29 is supplied to the decision unit 27 so that the decision unit 27 is able to detect a small average motion B if the average motion signal is lower than the threshold value m.
This second event B is e.g. detected when the motion signal is slightly larger than the minimum value ever recorded for the motion signal. This can be implemented in that the motion signal is compared to the second threshold m, which is smaller than the first threshold M. For the detection of the second event B it is preferably the averaged value of the motion sensor that is compared to the second threshold m. * **
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A third event that can be identified by the motion sensor is a large average motion C. output of the integrator 28 can thereby be applied to a comparator 31 that compares the average motion signal with a threshold value m' that can be stored in a storage unit 32. The output of the comparator 31 is supplied to the decision unit 27 so that the decision unit 27 is able to detect a large average motion C if the average motion signal is higher than the threshold value m'.
Thereby, the instantaneous value of the motion signal differs from the averaged value of said motion signal. The instantaneous value refers to the current, i.e. instantaneous intensity of motion within the area covered by the sensor. Such an instantaneous value is for example used in the state of the art, in which the light source connected to the motion sensor is turned on as soon as this instantaneous value is higher that a given threshold. On the other hand, the averaged value of the motion sensor consists in values averaged over for example a few seconds. Such an averaged signal is e.g. not used in a known threshold and delay sensor because it would introduce a corresponding delay of a few seconds in the reaction of the 3o sensor: in such a case, the sensor would become slow and react a few seconds after the motion has happened, which is not desired.
In the sense of the present Invention, an averaged value of the 35 motion signal therefore refer to an average over a given time period Ta of preferably at least one second, preferably at least two seconds more preferably at least two or more seconds, like for example 5 seconds. On the other hand, the input of the comparator is an instantaneous value of the motion signal amplitude. Thereby it is possible that the processing unit 23 performs an electrical noise reduction and a filtering: however for this task, the sampling frequency and the number of samples are chosen so that the value of the instantaneous motion signal remains instantaneous and at most relates to a few milliseconds.
In a preferred embodiment, the decision unit 24 detects preferably the three different events that are a large instantaneous motion A, a small average motion B, and a large average motion C. Alternatively, the decision unit 24 may be able to detect only parts of these three events. *
****^ * initialized at the value zero. If the counter reaches a given * **-*** * * 20 value z, the motion sensor 1 generates a coded voltage for turning on the light source 4. On the other hand, if the * * , g * .0 counter decreases and reaches the value zero again, the motion 4,8^ 41 * sensor 1 generates a coded voltage for turning off the light source 4.
The counter value is modifiec as follows. Upon detection of a large instantaneous motion A by the decision unit 27, the value of the counter is increased by the value z. Preferably, this value z is also the maximum value that can be taken by the 3o counter. Upon detection of a small average motion B, the value of the counter is decreased by a value x. Finally, upon detection of a large average motion C, the value of the counter is increased by a value y. This value y may be different from the value x.
* ** * *.**** As shown in Fig. 2, the decision unit 27 comprises a counter.
****** The value of the counter is used to identify the presence state * , P or the non-presence state NP. The value of the counter is A possible evolution of the counter value is illustrated in Fig. 3a, 3b, and 3c. * * * * * *
* * * * * * * * * * . ** * * * * * * * * * * * * * * Fig. 3a shows an embodiment wherein the system, particularly the motion sensor 1, detects a large instantaneous motion A as soon as the instantaneous value of the motion signal is higher than said threshold M. The counter value is initialized at the value zero for example when the motion sensor 1 is turned on and, as soon as the large instantaneous motion A is detected, the counter is increased to the value z. Once the counter has the value z, further detection of large instantaneous motions A will preferably not affect the counter since the value z is preferably the maximum value of the counter. Fig. 3a shows that after the first detection of the event A, the counter remains at its maximum value z. Consequently, the light source 4 is switched off from t=0 to t=t1 and switched on at t=t1.
Fig. 3b shows how the counter is influenced by the detection of a small average motion B. The embodiment shows that in case the second event B is detected, the counter is decreased by the value x, wherein if the counter reaches the value zero, the light source 4 is turned off.
Fig. 3b shows particularly an embodiment, in which several small average motions B are detected successively. At the time point t=0, the counter has the value z, which means that for example the first event A has been detected prior to this time point and that the light source is on at t=0. The shown signal is here the averaged motion signal, preferably corresponding to the amplitude of the motion signal averaged over a time period Ta, wherein this time period Ta corresponds preferably to at least one second or a few seconds as described above. In the embodiment of Fig. 3b, several values of the averaged motion signal are therefore calculated at t=Ta, t=2. Ta, and 3. Ta. These three averaged values are all below the second threshold m, such that the second event B is detected respectively at the moments Ta, 2.Ta and 3.Ta. * * * * * *
* * * . * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * As a reaction of the detection of said second event B, the counter is decreased by the value x. After t=Ta, the counter as the positive value z-x and the light source is still lightening. After the moment t=2.Ta, the value of the counter 5 z-2.x is still positive and the light source 4 is still lightening and the light source 4 is still lightening. As soon as the counter reaches the value zero or falls below zero, the light source is turned off. This happens in the embodiment of Fig. 3b upon the third detection of the small average motion B lo at the moment t=3.Ta.
In fact, if the counter falls below zero and presents a negative value, the counter is preferably re-initialized to the value zero and the light source 4 is kept turned off.
Fig. 3c shows how the counter is influenced by the detection of a large average motion C. The embodiment shows that in case the second event C is detected, the counter is increased by the value y, wherein if the counter reaches the value z, the light source 4 is turned off.
In this embodiment, the counter value is zero at the time point t=0. The time period for averaging the motion signal is Ta, so that the average motion signal can be compared to the threshold value m' stored in storage unit 32 at the moments t=Ta, t=2.Ta, and 3.Ta. At t=Ta, the average value is below the threshold m' such that the counter is not modified. At t=2.Ta and t=3.Ta the average value is above said threshold m' so that the counter is successively increased by the value y. At t=3.Ta, the counter is limited to its maximum value and the light source 4 is switched on.
The motion sensor 1 of the present invention in adapted to change autonomously its behaviour depending on ongoing motion 35 sensing. This means among others that the motion sensor 1 changes autonomously its behaviour preferably depending on the ongoing detection of large instantaneous motion A, small average motion B and large average motion C. The motion sensor 1 changes preferably its behaviour in an autonomous way, i.e. without any external instruction given by e.g. an operator. This change of behaviour is achieved by modifying at least one of the first threshold M, the second threshold m, the third threshold m', the value z, the value x and the value y.
A first possible adaptation of the motion sensor 1 relates to the particular case that, after the light source 4 is turned on for example as a consequence of a detected large instantaneous motion A, the events that are detected are only small average motion events B. The decision unit thus detects a first large instantaneous motion A that is followed by a succession of small average motions B. The event sequence corresponds to {A, B, B, B). Correspondingly, the counter will be increased to its maximum value z and then decreased successively by the 20 value x until it reaches the value zero.
The decision unit 27 is adapted to recognize this event succession, and is particularly adapted to recognize that only small average motions B have caused the counter to decrease from its the maximum value to zero. In this case, the behaviour of the motion sensor 1 is adapted by decreasing the value z and/or increasing the value x.
After this adaptation, a similar event sequence {A, B, B, B) will cause a more rapid switching off of the lamp. This is e.g. advantageous for a corridor application, where motion sensor and light source are installed in a corridor. Indeed, corridors are usually empty except when someone is going through them, but very seldom people stop in corridors. In such an application therefore, the event sequence {A, B, B, B) may occur often. An adaptation consisting in decreasing the value z and/or increasing the value x thus will lead to the situation * * * * * * * . * * * * * * * * * * * * * * * that the light will turn off much more quickly in said corridor application.
A further autonomous adaptation relates to the detection of a large instantaneous motion A followed by a sequence of small and/or large average motions B, C. The corresponding event sequence can be e.g. (A, B, C, C, B, C, C}. In other words, the light source 4 is turned on after a large instantaneous motion A and is later on turned off after a succession of average motions B, C without further large instantaneous motion A. In such a scenario, it is possible that the first threshold M for detecting a large instantaneous motion A may be too high, such that the autonomous adaptation could then consist in reducing the value of the first threshold M. * * * * * * A further autonomous adaptation is proposed e.g. when the * * * * * counter, starting from the value zero, reaches its maximum * * value z without any detected large instantaneous motion A. In * * * * * * * * 20 other words, the light source is turned on after a succession of small and/or large average motions B, C. The corresponding * * * event sequence can be e.g. fC, B, C, C, B, C, C}. * * * * * * * * * *
In this application, the command i.e. the coded voltage for turning on the light source 4 is delayed because the counter is increased only based on large average motions C. The reaction of the system and of the motion sensor can then be speeded up by decreasing the first threshold M for facilitating the detection of the large instantaneous motion A. A further autonomous adaptation is proposed if a small average motion B has not been detected by the decision unit 27 since a long time or more generally since a predetermined time of e.g. a few hours, one day or several days. The system indeed expects some quite period from time to time: an adaptation consists then in such a case in increasing the threshold m for increasing the probability of detecting a small average motion * * * * * * * * * . * * * * * * * * * * * * * * . . * * ** * * ** B. As a consequence, the counter will be decreased by the value x more often. This situation applies for example to an office application, where it is expected that at least during the night the threshold M shall be exceeded.
Regarding the different threshold values, the second threshold m for detection of a small average motion B is preferably lower than the first threshold M for detection of a large instantaneous motion A. Preferably, the third threshold m' can io be linked to the second threshold m in such a way that the difference m'-m is a fixed value. Adapting or modifying e.g. the threshold m would thus automatically result in the adaptation or modification of the threshold m'.
The proposed autonomous adaptation thus influences for example how quickly or slowly the light will turn off. The advantage of this solution is that the behaviour of the motion sensor can be adapted without requiring any additional work from an operator.