WO2012052750A1

WO2012052750A1 - Motion sensitive system and method of generating a control signal

Info

Publication number: WO2012052750A1
Application number: PCT/GB2011/052011
Authority: WO
Inventors: Steven Carle; Alan Pemberton
Original assignee: Intelligent Door Solutions Limited
Priority date: 2010-10-18
Filing date: 2011-10-18
Publication date: 2012-04-26
Also published as: GB201017540D0; GB2484668A

Abstract

A motion sensitive system that generates a control signal when a target is validly approached by a moving object. The system comprises a sensor arrangement (15) which captures a plurality of images (21, 22) of the moving object, moving in proximity to the target (10). A processing module (17), which is arranged to perform image recognition, receives the plurality of images (21, 22) from the sensor arrangement (15) and calculates the velocity of the moving object (10) before referencing the velocity of the moving object (10) with a predetermined threshold. The processing module (17) is also arranged to generate a control signal (39) in response to the calculated threshold satisfying a predetermined criterion with respect to the predetermined threshold. This invention further includes a method for generating a control signal when a target is validly approached by a moving object.

Description

MOTION SENSITIVE SYSTEM AND

METHOD OF GENERATING A CONTROL SIGNAL

[0001] This invention relates to a motion sensitive system, and in particular to a motion sensitive system which generates a control signal when a target is validly approached. This invention further relates to a method of generating a control signal.

[0002] There are many devices, such as automatic doors, escalators, and barriers which only operate when a moving object, normally a person and sometimes a vehicle, are detected in the proximity of that device.

[0003] Taking automatic doors as an example, these generally comprise one or more doors attached to an electrically operated door opening mechanism which either swings or slides the door open. Automatic doors further include a proximity sensor, usually an infrared sensor or a microwave radar sensor. These proximity sensors will generally monitor an area in front of the door and if the sensor detects a person entering the area, a control signal will be sent to the door opening mechanism which will then open the door.

[0004] These prior art systems have the disadvantage that they will be operated whenever a person walks into the area being monitored, regardless of whether they intend to walk through the door or not. If a person merely walks past but near enough to the door to enter the area monitored by the sensor, it will still open. This has the obvious disadvantage of unnecessary wear and tear on the door opening mechanism, and will also have an environmental impact if the building to which the doors are fitted is air conditioned or heated, as well as causing increased power consumption by the door mechanism. [0005] This invention seeks to address the problem of such devices being unnecessarily operated, by providing a system that only triggers the operation of these devices when they are truly approached. Therefore, according to the present invention there is provided a motion sensitive system that generates a control signal when a target is validly approached by a moving object, said system comprising: a sensor arrangement which captures a plurality of images of a moving object, moving in proximity to the target; a processing module arranged to perform image recognition, the processing module receiving the plurality of images from the sensor arrangement and calculating the velocity of the moving object before referencing the velocity of the moving object with a predetermined threshold; wherein the processing module is also arranged to generate a control signal in response to the calculated velocity satisfying a predetermined criterion with respect to the predetermined threshold..

[0006] According to a second aspect of the present invention there is provided a method of generating a control signal when a target is validly approached by a moving object, said method comprising the following stages: a sensor arrangement captures a plurality of images of a moving object, moving in proximity to the target; a processing module, which is arranged to perform image recognition, receives the plurality of images from the sensor arrangement and calculates the velocity of the moving object before referencing the velocity of the moving object with a predetermined threshold; and the processing module generates a control signal in response to the calculated velocity satisfying a predetermined criterion with respect to the predetermined threshold.

[0007] Reference will generally be made herein in relation to automatic doors, unless otherwise specified, as this is one such situation where this invention can usefully be provided. However, other powered devices that are operated by proximity thereto would also benefit from this invention, such as escalators, lifts or barriers. Automatic doors generally have an electrically driven motor to operate them and further include proximity sensors as described above, mainly utilising infrared or microwave radar. The present invention may utilise these drive motors, and work in conjunction with the pre-existing proximity sensors. In one embodiment, the motion sensitive system may further include a proximity sensor, and the proximity sensor may be an infrared sensor or a microwave radar sensor. In this embodiment, the opening mechanism will only be triggered if a control signal is received from both the proximity sensor and a motion sensitive sensor. However, without a control signal from the motion sensitive sensor, the proximity sensor will be inhibited. Alternatively, a motion sensitive system could be the only system used to trigger the opening of the door. Whilst automatic doors could be produced which incorporate the motion sensitive system, the system could also be retrofitted to pre-existing automatic doors. Whilst the present application could apply to the automatic doors of a building, it could also apply to automatic doors on a vehicle such as a bus or a train.

[0008] Optionally, temperature sensors linked counting means could be provided on the inside and outside of the door to calculate the temperature difference between each side of the door. By counting the number of times that the opening of the door by the proximity sensor had been inhibited by the motion sensitive system, an energy saving can be calculated based on the temperature difference. Temperature sensors could also be used to calibrate the motion sensitive system so that it is less sensitive (and as a result the door is less likely to open) if there is a greater temperature difference between the outside and inside of the door, for example during the winter, than if the difference in temperatures were smaller.

[0009] In a further embodiment of the present invention, the signal generated could operate an alarm. One use of this embodiment would be as part of a warning system for use with lorries or other vehicles. In particular, the sensor arrangement can be deployed to monitor the blind spot of a lorry. If a cyclist, for example, pulls into the blind spot, its motion into the blind spot would be sufficient to trigger the alarm and notify the driver that the cyclist was there.

[0010] Any means which can detect the velocity (velocity being understood to mean a vector of the speed and direction) of the moving object could be used as the sensor arrangement, though for most practical purposes, such as when applied to automatic doors or escalators, the sensor arrangement may comprise a video camera, for example a web-camera. Web-cameras have the further advantage of being cost effective for day to day use, which is particularly important considering that many such systems according to the present invention could be used within a single premises. The sensor arrangement could also comprise one or more infra-red camera, which can help to distinguish between people and inanimate objects should this be required. For example, if the target were a door, a motion sensitive system including an infra-red camera might reduce the number of false openings by only opening when a person approaches the door. However, other sensor arrangements such as ultrasound could conceivably be used. Whilst a single camera will generally be used, it has been found that in certain circumstances multiple cameras linked together provide an increased field of vision. For example, two linked cameras will be preferable for identifying one person positioned behind another, or if there is an unusual door layout.

[0011] If the sensor arrangement comprises one or camera, this could be part of a security camera arrangement and linked into a building management system. [0012] The processing module receives information from the sensor arrangement which it analyses to see if relevant motion is detected. In order to do this, the processing module contains image recognition software which tracks the movement of the moving object. Image recognition software that can track the motion of an object is known per se, for example as provided in EP0567059 or EP0474307, and software such as this could form the basis for the software used by the processing module of the present invention.

[0013] In one embodiment, the processing module calculates the position and velocity of the moving object, and references the position and velocity of the moving object with a predetermined positional threshold. The processing module may be arranged to generate a control signal in response to the calculated position and velocity satisfying a predetermined criterion with respect to the predetermined positional threshold. [0014] In one embodiment, the positional threshold may comprise two or more data (more than one datum), for example in the form of virtual markers arranged substantially perpendicular to how the moving object would normally approach the device. A signal could then be generated if the moving object passes two or more data within a certain time period. In the case of an automatic door, the data would be positioned in parallel with the doorway and spaced apart from each other, and in the case of an escalator the data would be also parallel and spaced apart in front of said escalator. The trajectory of a person approaching a door, for example, would be different to that of someone simply walking past. Therefore the data will be arranged so that they would only be crossed within a particular time frame by a person who is approaching the door. Whilst prior art automatic doors would be opened by a person walking past the door within the monitored area, a door operated by the system of the present invention would open only when approached.

[0015] Alternatively, the threshold could comprise one or more data, for example in the form of virtual markers, arranged substantially in line with how the moving object would normally approach the target.

[0016] The data could be drawn physically on the ground and recorded by the image recognition software, or alternatively could be defined in software.

[0017] The system may then continue to detect the motion, and when no more relevant motion is detected towards the door for a predefined period of time, the closing mechanism is triggered. If further relevant motion towards the door is identified, the door closing is interrupted and opening of the door is triggered again. [0018] It is thus possible to provide a motion sensing apparatus and a method of generating a control signal that reduce wear of electromechanical machinery that employ crude sensors to initiate activation thereof. The apparatus and method also contribute to saving of electrical power both through operation of the electromechanical machinery and, for example in the case of automatic doors, maintenance of environmental conditions, for example temperature, within a building. The above-mentioned energy savings also translate into cost savings both in relation to running costs of the electromechanical machinery but also environmental heating or cooling costs. In particular, the apparatus and method of the present invention would significantly save wear and tear on a door or related devices and mechanisms and thus increase the useful life thereof. Furthermore, the environmental improvement resultant from the present invention would be beneficial to the owners of particular buildings in terms of enhanced reputation, particularly as green issues are at the forefront of public policy. So called "green leases" for property require adherence to particular energy saving criteria, which would be met or improved upon by this invention. Furthermore financial incentives are often provided to increase energy efficiency. It should also be appreciated that the apparatus and method is equally applicable for internal use within a building as well as in relation to external doors, for example in a hospital.

[0019] In the context of an automatic door system, as a result of a decrease in the number of false activations of a door, the method and apparatus also minimises disruption and/or inconvenience to personnel working within a building in relatively close proximity to the door.

[0020] So it may be better understood, at least one embodiment of the present invention will now be described in detail, but by way of example only, with reference to the following drawings, in which:

Figure 1 shows a schematic plan view of an automatic door incorporating the present invention;

Figure 2 shows a schematic cross sectional side view of the door of Figure 1 ;

Figure 3 shows a schematic diagram of the processing module;

Figure 4 shows a flow diagram of an algorithm used by the present invention; Figure 5 shows a first and second captured image of a person;

Figure 6 shows a first and second captured image with a bounding box and centroid; Figure 7 shows a first and second captured image of a person as shown in Figure 6 including the marker lines; Figure 8 shows a schematic plan view of an automatic door incorporating a second embodiment of the present invention;

Figure 9 shows a schematic plan view of an automatic door incorporating a fifth embodiment of the present invention;

Figure 10 shows a flow diagram of an alternative algorithm used in the fifth embodiment of the present invention; and

Figure 11 shows aa first and second captured image with a bounding box centroid and marker lines of the fifth embodiment of the present invention.

[0021] Referring initially to Figures 1 and 2, there is shown a door, generally indicated 10, comprising a pair of slidably mounted leaves 1 1 over a doorway 12 in a wall 13. The door 10 includes a motorised opening mechanism 14 which is arranged to slidably open both of the leaves 1 1 .

[0022] The door opening system further comprises a sensor arrangement to detect the presence of a person in the form of twin linked video cameras 15. The cameras 15 are mounted to the top corners of the doorway 12 and monitor a space 20, which is marked by dotted line 16 and constitutes a plan view in front of the door 10. The cameras 15 are connected to a processing module 17, which may be situated by the doorway 12 or remotely accessible via cable or wireless transmission. Alternatively, a single camera, for example centrally mounted above the doorway, could be provided. The processing module 17 in turn is in communication with the motor of the door opening mechanism 14. Of course, if the processing module 17 is remotely located, then further remote transmission apparatus is required so that the processing module 17 can communicate with the door opening mechanism 14. Referring to Figure 3, the processing module 17 comprises a microprocessor 23 having Random Access Memory (RAM) 26 and digital memory 27. The microprocessor 23 is linked to a video interface 24, which is in communication with the two cameras 15, and a door opening interface 25 which is in communication with the door opening mechanism 14. The processing module 17 supports execution of motion sensing functionality, further details of which will be described later herein, which generates a control signal if a person approaches the door 10. The cameras 15 produce a plurality of image signals which are combined by the processing module 17 to generate a single image, an example of which is shown in Figure 5.

[0023] Defined in the software of the processing module 17 are a set of so-called virtual marker lines which have been superimposed at a predetermined position relative to the doorway 12. Figures 1 , 2 and 7 show the position of these marker lines, which are indicated by broken lines 30, 31 and 32. In this embodiment, these marker lines 30, 31 , 32 are not physically marked on the ground, and their position has been shown in the Figures for exemplary purposes, though alternatively physical marker lines could be provided on the ground. The position of the marker lines 30, 31 , 32 is determined so that they are arranged substantially perpendicular to the movement of a person approaching the door 10 in a normal fashion, and therefore are for the most part parallel with the door 10. However, the marker lines arc toward the wall 13 at their far edges in common with a person approaching the door 10 from an angle. A person crossing the virtual marker lines within a certain period of time would be considered to be approaching the door, and this would be sufficient to cause the creation of a control signal which will trigger a door opening.

[0024] In operation, a person approaching the door 10 to go through it will cross at least two of the marker lines within a certain period of time. The processing module 17 identifies a moving object captured by the cameras 15, and calculates whether it is approaching the door, the approach being defined with respect to passage through the marker lines 30, 31 , 32. The software implements the following algorithm, as identified in Figure 4: In the first stage 34 of the algorithm, the cameras 15 capture video images of the area 20 in front of the door 10, indicated by line 33 in Figure 7. Figure 5 shows two captured images of a person within area 20, separated by a certain timeframe - the first image 21 of the person was taken initially, and then the second image 22 was taken shortly afterwards. In the second stage 35 of the algorithm, the captured images from the camera are then separately converted into monochrome images, as shown in Figure 6. In the third stage 36, if a change of position is identified in any area within the region being monitored, this area will be marked as an "Identified Motion Area", or IMA. In the fourth stage 37 a bounding box 40 is then defined around the IMA, and the centroid 41 of the bounding box 40 is located. In the fifth stage 38, the position and velocity of the moving object is calculated from the centroids 41 , as indicated by line 42, and checked with respect to the marker lines, for example to see whether the threshold value is exceeded. If motion towards the door 33 is identified as a result of the marker lines being crossed in a predetermined direction and within a predetermined period of time, then the processing module 17 generates a control signal to trigger the operation of the opening mechanism 14 of the door 10. [0025] In a second embodiment, as shown in Figure 8, there is further provided a secondary sensor in the form of an infrared sensor 50, which works in conjunction with the motion sensitive sensor system of the first embodiment. As the second embodiment includes all of the features of the first embodiment, like reference numerals will be used to identify like parts. The infrared sensor 50 is connected to the processing module 17 and will detect a person entering within the area 20 identified by dotted line 16. If a person is detected a signal 51 will be sent to the processing module 17. The processing module will detect movement as described in the first embodiment, but will only generate a signal to open the door if it also receives a signal 51 from the infrared sensor 50. Alternatively, the infrared sensor 50 can be used as the primary trigger for a decision as to whether to activate the door opening mechanism 14 in order to open the door 10, the activation of the door mechanism being confirmed by the control signal generated by the processing module 17.

[0026] As shown in Figure 7, the position of the door 33 and the marker lines 30, 31 , and 32 are defined in software. This means that the software can easily be applied to other situations, such as in a third embodiment, which is not shown here. In this third embodiment, the motion sensitive system of the present invention is applied to an escalator. The system operates to trigger the movement of an escalator when it is approached, so that it is not constantly running. The line 33 which represents the "door" in the previous embodiments and can be defined to be in front of the entrance to the escalator. The marker lines 30, 31 , 32 can then be suitably positioned parallel to the "door" line 33.

[0027] Careful calibration is required in each situation to ensure that the marker lines are correctly placed. Physical lines can be drawn on the ground and monitored by the sensor arrangement and the human eye so that a database of movements towards a target (and past or away from the target) can be recorded so that subsequently marker lines can be defined in the software that correspond to purposeful movement towards the target.

[0028] In a fourth embodiment, not shown here, a camera monitors the blind spot by the side of a vehicle such as a lorry. The camera is linked to a processing module which identifies objects passing into the area being monitored, in particular cyclists which are passing by on the inside of the lorry. The processing module operates an algorithm as before. If movement made by the cyclist relative to the lorry is sufficient to pass the threshold, a control signal is created which sets off an alarm, alerting the driver of the lorry to the presence of the cyclist.

[0029] A fifth embodiment is shown in Figures 9 - 1 1 . This embodiment is applied to a doorway as described in relation to the first embodiment, and so the same reference numerals will be used for like parts. A set of so-called virtual marker lines which have been superimposed at a predetermined position relative to the doorway 12 are defined in the software of the processing module 17. Figures 9 and 10 show the position of these marker lines, which are indicated by broken lines, 45, 46 and 47. In this embodiment, these marker lines 45, 46, 47 are not physically marked on the ground, and their position has been shown in the Figures for exemplary purposes, though alternatively physical marker lines could be provided on the ground. The position of the marker lines 45, 46, 47 is determined so that they are substantially in line with the movement of a person approaching the doorway 12 in a normal fashion. A person walking substantially in line with the virtual marker lines 45, 46, 47 within a certain period of time would be considered to be approaching the door, and this would be sufficient to cause the creation of a control signal which will trigger a door opening.

[0030] In operation, a person approaching the door 10 to go through it will approach the door within a range of velocities (i.e. within a range of speeds and within a range of directions), the direction component thereof being described by the marker lines 45, 46, 47 and the speed component being defined by the speed a person approaches the door. The processing module 17 identifies a moving object captured by the cameras 15, and calculates whether it is approaching the door, the approach being defined with respect to the marker lines 45, 46, 47 and the speed of the person. The software implements the following algorithm, as identified in Figure 10: In the first stage 55 of the algorithm, the cameras 15 capture video images of the area 20 in front of the door 10, indicated by line 16 in Figure 9. Figure 1 1 shows two captured images of a person within area 20, separated by a certain timeframe - the first image 61 of the person was taken initially, and then the second image 62 was taken shortly afterwards. In the current example, the two images are separated by five video frames, though this figure depends on the camera frame rate. In the second stage 56 of the algorithm, the captured images from the camera are then separately converted into monochrome images. In the third stage 57, if a change of position is identified in any area within the region being monitored, this area will be marked as an "Identified Motion Area", or IMA. In the fourth stage 58 a bounding box 63 is then defined around the IMA, and the centroid 64 of the bounding box 63 is located. In the fifth stage 59, the velocity of the moving object is calculated from the centroids 64, as indicated by line 65, and checked with respect to the marker lines to gauge direction, for example to see whether the threshold value of predetermined velocitiesis exceeded. If motion towards the door 33 is identified as a result of the marker lines being crossed in a predetermined direction and within a predetermined period of time is identified, then the processing module 17 generates a control signal to trigger the operation of the opening mechanism 14 of the door 10.

Claims

1 . A motion sensitive system that generates a control signal when a target is validly approached by a moving object, said system comprising:

a sensor arrangement which captures a plurality of images of a moving object, moving in proximity to the target;

a processing module arranged to perform image recognition, the processing module receiving the plurality of images from the sensor arrangement and calculating the velocity of the moving object before referencing the velocity of the moving object with a predetermined threshold; wherein

the processing module is also arranged to generate a control signal in response to the calculated velocity satisfying a predetermined criterion with respect to the predetermined threshold.

2. A motion sensitive system as claimed in Claim 1 , wherein the processing module calculates the position and velocity of the moving object, and references the position and velocity of the moving object with a predetermined positional threshold, the processing module being arranged to generate a control signal in response to the calculated position and velocity satisfying a predetermined criterion with respect to the predetermined positional threshold.

3. A motion sensitive system as claimed in Claim 2, wherein the predetermined positional threshold comprises two or more marker lines arranged substantially perpendicular to how the moving object would normally approach the target.

4. A motion sensitive system as claimed in Claim 3, wherein the control signal is generated if the moving object passes two or more marker lines within a certain time period.

5. A motion sensitive system as claimed in Claim 1 , wherein the threshold comprises one or more datum in the form of one or more marker line substantially in line with how the moving object would normally approach the target.

6. A motion sensitive system as claimed in Claim 5, wherein the control signal is generated if the direction component of the velocity of the moving object is substantially in line with at least one marker line within a certain time period.

7. A motion sensitive system as claimed in any of the preceding claims, wherein the sensor arrangement comprises one or more video camera or web- camera.

8. A motion sensitive system as claimed in any of the preceding claims, wherein the signal triggers the operation of a powered device.

9. A motion sensitive system as claimed in Claim 8, wherein the powered device is an automatic door, an escalator, or a lift.

10. A motion sensitive system as claimed in any of the preceding claims, wherein the control signal triggers the operation of an alarm.

1 1 . A motion sensitive system as claimed in any of the preceding claims, wherein the sensor arrangement further includes a proximity sensor.

12. A motion sensitive system as claimed in Claim 1 1 , wherein the proximity sensor is an infrared sensor or a microwave radar sensor.

13. A motion sensitive system as claimed in Claim 1 1 or Claim 12, wherein the proximity sensor generates a control signal which is inhibited by the motion sensitive system.

14. A method of generating a control signal when a target is validly approached by a moving object, said method comprising the following stages:

a sensor arrangement captures a plurality of images of a moving object, moving in proximity to the target;

a processing module, which is arranged to perform image recognition, receives the plurality of images from the sensor arrangement and calculates the velocity of the moving object before referencing the velocity of the moving object with a predetermined threshold; and

the processing module generates a control signal in response to the calculated velocity satisfying a predetermined criterion with respect to the predetermined threshold.