Abstract:
A monitoring system for an infant, child, invalid, or other person requiring care uses computer vision and hearing, and inputs of other modalities, to analyze the status of a caretaker and/or cared-for person and its environment. The conditions are classified as normal or alarm conditions and an informative alarm signal is generated which may include records of the vision audio and other inputs. The system also has the ability to solicit responses from the occupants to stimulate a classifiable input to reduce ambiguity in its state signal.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to devices that generate an alarm signal when conditions surrounding an invalid, infant, or child, or other person or a caretaker thereof, warrant it. 
   2. Background 
   Remote security monitoring systems in which a video camera is trained on a subject or area of concern and observed by a trained observer are known in the art. Also infant or child monitors that transmit audio to a portable receiver are available in the market. These devices, however, require constant attention in order to provide protection to the subject or area of concern, such as an infant or child. 
   Automated infant or child monitors have been proposed which, for example, monitor an infant&#39;s sleeping position to help prevent sudden infant or child death syndrome (SIDS). One approach, suggested in U.S. Pat. No. 5,864,291 uses a breathing-sensing strap around the infant&#39;s torso to detect breathing. Another (U.S. Pat. No. 5,638,824) suggests using an ultrasonic sensor and U.S. Pat. No. 5,914,660 position sensors for the same purpose. The automation in these types of monitors, however, provide little use for babies that are distressed for reasons other than a failure to breathe or sleep in an expected position. Also, the alarm signal may contain false positives and is of little help in diagnosing the cause of distress. 
   A monitored person&#39;s physical and emotional state may be determined by a computer for medical diagnostic purposes. For example, U.S. Pat. No. 5,617,855, hereby incorporated by reference as if fully set forth herein, describes a system that classifies characteristics of the face and voice along with electroencephalogram and other diagnostic data to help make diagnoses. The device is aimed at the fields of psychiatry and neurology. This and other such devices, however, are not designed for monitoring persons in their normal environments. 
   In still another application area, machines automatically detect an occupant&#39;s presence or specific features of the occupant for purposes of machine-authorization and authentication or convenience. To that end, some prior art systems employ biometric sensing, proximity detectors, radio frequency identification tags, or other devices. 
   EP 0716402B1 describes a method of detecting the number of people entering a train or other space using infrared sensors and fuzzy inference techniques. When the number of people is outside desired limits or unbalanced, the system can generate notices to that effect which may be linked to devices to correct the condition. 
   UK 2027312A describes a method of detecting the movement of fish using IR cameras generating a standard video signal. 
   U.S. Pat. No. 4,524,243 describes a system in which a user is required to activate a switch at specified intervals. Failure to do so results in the generation of an inactivity alarm. 
   U.S. Pat. No. 5,905,436 discloses a system in which the failure of various sensors in a home to be triggered results in the generation of a signal at a central monitoring station indicating such. The disclosure is directed at the supervision of an elderly person living at home. 
   UK 2179186A describes a system in which, if movement not detected at a pre-determined time, an alarm is triggered. A warning is given so that the user can reset the switch. 
   U.S. Pat. No. 6,002,994 discloses a system in which transmitters, placed at strategic locations in a house, are triggered whenever a person is present at the location of a sensor triggering the transmitter. Also, the system employs other inputs attached to devices and appliances that the user is expected to use. The system is trained to recognize normal patterns of use. The transmitters transmit a signal to a central monitor if the normal pattern is not followed. 
   In this reference, physiological measurements may include the user&#39;s blood pressure, heart rate, body temperature, body weight and blood glucose level. Non-physiological measurements may include room temperature, ammonia from spilled urine, methane from spoiling food, a presence of smoke, frequency of electrical usage, frequency of water usage, temperature of water flowing from a tap, the user&#39;s movement within the selected environment as indicated by motion sensors, and use of appliances including a toilet, telephone, stove, microwave oven, toaster, oven, refrigerator, freezer, dishwasher, bath, shower, garbage disposal means, clothes washer, clothes drier, mail box, door and vehicle. 
   Machine identification of faces is a technology that is well-developed. In GB 2343945A for a system for photographing or recognizing a Face, a controller identifies moving faces in a scene and tracks them to permit image capture sufficient to identify the face or distinctive features thereof. For example, the system could sound an alarm upon recognizing a pulled-down cap or face mask in a jewelry store security system. 
   There remains a need in the present art for a system that monitors persons requiring supervision to be more robust, capable of responding to more subtle cues and provide more informative information to supervisors. 
   SUMMARY OF THE INVENTION 
   Briefly, an alarm system monitors conditions of a person requiring care, others attending to that person, and the environment of that person. The alarm system generates an informative alarm signal or message containing information about the these factors to help the message recipient understand what is going on. In an embodiment, the alarm signal is a live video and/or audio feed from a camera trained on the person requiring care. In another embodiment, the alarm signal is a symbolic set of data relating to the status and the condition that generated the alarm, for example, the message “Person requiring care not attended to in 3 hrs,” “No movement detected in 20 min.,” “Stopped breathing,” or “Caretaker absent.” In still other embodiments, the system generates responses to stimulate action, such as a response from a caretaker that is on the premises. The alarm signal may be transmitted by phone line, the Internet, or a wireless channel. 
   The field of artificial intelligence and robotics has given rise to technology that enables machines to make sufficient sense of their surroundings to recognize predefined conditions, navigate vehicles, and identify objects and their orientations, for example. Components of systems called autonomous observers have been made in the lab which allow a machine to follow an observer in an area and track escape routes. Other applications of similar technology include video tracking systems that follow a speaker giving a presentation and respond to the speaker&#39;s gesture commands. In embodiments of the present invention, the technology of image and video recognition, audio recognition, and other inputs may be applied to infer the condition of a monitored person requiring care. 
   Artificial intelligence (AI) principles are used by a classification engine receiving video, audio, and/or other inputs to model a current situation. When conditions are classified as calling for attention (distress event), video, audio, and other data that may be buffered up to the distress event, as well as live data, may be transmitted to a monitor along with an indication of the class to which the recognized event belongs. For example, the audio signal generated by a crying person requiring care may be classified as a “person-crying” condition either alone or in concert with the classification of other data such as video data of the crying person requiring care. Condition classes for a suitable monitor system may include events such as:
         1. trigger by a breathing sensor, motion sensor, or audio sensor as in prior art devices,   2. delay in response time of a nanny or au pair or other care-giver given to a person requiring care,   3. movement (crawling) of the person requiring care into prohibited areas of a room,   4. sudden movement consistent with falling, running, normal walking, crawling, etc.,   5. lack of normal movement such as rapid movement such as an infant or child being picked up at a time other than a previously defined time,   6. presence of the person requiring care or other individuals in a space and their number,   7. consistency of the clothing, facial features, etc. of the occupants of a space throughout a period of time.   8. loud sounds, normal sounds, and unusual sounds, based upon signature of sound,   9. location of sound source,   10. occupancy of unauthorized spaces,   11. occupancy patterns, for example whether care-giver is spending unusual amounts of time away from person requiring care or care-giver is spending unusual amounts of time in a particular space,   12. patterns consistent with damage to the monitoring system,   13. voice signatures of unauthorized occupants or unrecognized voice signatures,   14. body habitus and physiognomy of occupants,   15. status of security system in the space,   16. unrecognized objects in occupied spaces or recognized objects being moved or found in unexpected locations,   17. temperature, humidity, sound levels, or other ambient variables out of normal range,   18. failure to detect face of a care-giver over crib for a specified interval,   19. presence of an unrecognized face or body pattern,       

   The event that triggers an alarm condition may be a simple one such as prior art sensors that monitor breathing or crying, or they may be more complex ones that integrate multiple inputs into a network to make decisions as to the alarm status. Such network devices may include classifiers in the form of neural networks, Bayesian networks, and other techniques for machine-recognition of physical objects and behaviors. The art in this field is rich and rapidly-growing and it is expected that improved means for implementing the current invention will continually become available. Preferably the classification engine is trainable so that it does not need to rely solely on predefined template patterns for pattern-matching. The system may be provided with the ability to generate a simulated dialogue to provide for assistance in training such as asking an occupant to select from among a number of condition classes present in a monitored space at a time when the occupant can observe the monitored space. 
   In an embodiment, the present invention may also employ simulated dialogue with a machine-generated persona such as disclosed in the following references, each of which is incorporated in its entirety as if fully set forth herein. 
   U.S. Pat. Ser. No. 09/699,606 for Environment-Responsive User interface/Entertainment Device That Simulates Personal Interaction; 
   U.S. Pat. Ser. No. 09/686,831 for Virtual Creature Displayed on a Television; and 
   U.S. Pat. Ser. No. 09/699,577 for User interface/Entertainment Device That Simulates Personal Interaction and Responds to Occupant&#39;s Mental State and/or Personality. 
   The persona may, in response to a particular condition (ambiguous classification of extant conditions or just on a random or interval time basis) request information from occupants about present circumstances. The feedback received may be used by the classification engine to further infer the extant conditions and/or relayed to a responsible party along with other information about circumstances. 
   The above applications also discuss the topic of classifying a rich array of inputs to make decisions about occupants. 
   The invention will be described in connection with certain preferred embodiments, with reference to the following illustrative figures so that it may be more fully understood. With reference to the figures, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of the preferred embodiments of the present invention only, and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the invention. In this regard, no attempt is made to show structural details of the invention in more detail than is necessary for a fundamental understanding of the invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the invention may be embodied in practice. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a schematic representation of a hardware system capable of supporting a monitor system according to an embodiment of the invention. 
       FIG. 2  is a high level flow diagram illustrating how inputs of various modalities may be filtered to generate an alarm signal consistent with several embodiments of the invention. 
       FIG. 3  is a functional diagram of a software system for implementing a monitor system according to an embodiment of the invention. 
       FIG. 4  is a flow chart illustrating the generation of an alarm signal according to an embodiment of the invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring to  FIG. 1 , in a hardware apparatus for implementing an embodiment of the invention, a programmable controller  100  receives input from various sources, for example, a connected image processor  305  connected to cameras  135  and  136 , microphone  112 , and sensors  141 . Sensors  141  may include alarm sensors such as breathing monitors or other SIDS prevention detectors or any other type of sensor such as temperature sensors, position sensors, security switches, proximity sensors, electrical load sensors, ambient light sensors, etc. Data for updating the controller&#39;s  100  software or providing other required data, such as templates for modeling its environment, may be gathered through local or wide area or Internet networks symbolized by the cloud at  110 . An Observer UI  122  and Server  140  are coupled to the network cloud  110 . The controller may output audio signals (e.g., synthetic speech or speech from a remote speaker) through a speaker  114  or a device of any other modality. For programming and requesting occupant input, a terminal  116  may be provided. 
     FIG. 2  illustrates how information gathered by the controller  100  of  FIG. 1  may be used to identify particular conditions and generate an alarm responsive to those conditions. Inputs of various modalities  500  such as video data, audio data, environmental conditions such as temperature, sound level, security system status, etc. are applied to a trained classifier  510  to discriminate and classify distinguishable features of a monitored environment. For example, the classifier  510  may be trained to discriminate faces and to classify them as belonging to one of a recognized set or not belonging to any member of the recognized set. For another example, the classifier  510  may be trained to classify sudden noises like breaking glass or falling objects. Still other examples are training it to recognize the emotional status and health of the monitored person by facial expression, physiognomy, body habitus, behavior, etc. from data in a video signal. Each classification of events/status may then be combined and further classified as an alarm condition. For example, the classifier may be trained to identify a loud sound followed by an unrecognized face as an alarm condition. 
   The technologies for training such classifiers as  510  are well developed and growing fast. Such classifiers may be trained explicitly using rules to form, for example, a Bayesian classifier. Alternatively, they may be trained using examples, as for training a neural net. Since the subject of how different kinds of classifiers are designed and trained is not the focus of the present invention, except as discussed herein, and because the technology for designing and training such classifiers is well-developed and highly varied, the particulars are not discussed in detail presently. Some interface for programming and/or training the classifier  510  is indicated  530 . The end goal of the classifier  510  is to output status or alarm information to an alarm output  520 . Both  530  and  520  may be networked terminals, cell phone devices, PDAs, or any suitable UI device. 
   Referring now to  FIG. 3 , a functional diagram of an event driven architecture that may be used to monitor an occupied zone separates the object illustrated by the single “black box” of classifier  510 , into multiple objects whose outputs are combined to classify alarm conditions. Audio input  245 , video input  255 , and other user interface devices (not shown) generate signals that are applied to respective classifiers  210 ,  240 . The audio input  245 , which may be received by a microphone (not shown separately) or a directional audio detector (not shown separately) which indicates both the sound and its direction, or any other suitable audio transducer, may be applied to an audio classifier  210 . The latter data form a real-time signal, which the audio classifier  210  classifies by suitable digital or analog means or a combination thereof. The audio classifier  210  then generates a current state information signal which it applies to both a mental state/health status classifier  290  and an event/class processor  207 . 
   To illustrate, the signal generated by the audio classifier may be a vector that includes the following components.
         1. Identity of speaker,   2. Number of speakers,   3. Type of sound (crashing, bumping, periodic, tapping, etc.)   4. Sound intensity level,   5. Duration, time of day, of distinguished sound,   6. Quality of speech (whispering, yelling, rapid, etc.)   7. Quality of voice (masculine, feminine, child, etc.),   8. Identified event (switching of a light, snoring, tinny sound of a radio or TV, vacuum cleaner, etc.)
 
Each instance of a discrete sound event and/or state may be combined with a time stamp indicating the time it began and, if it has, ended, and the combined vector signal applied to the event/class processor  207 .
       

   A video image classifier  240  receives video input  255 , classifies image data and generates state information signals which are applied to the mental state/health status classifier  290  and the event/class processor  207 . The video image classifier  240  may be programmed to identify certain events such as gestures, rapid movement, number of occupants in its field of view, etc. Like the audio classifier  210 , its output may be a vector which, for illustrative purposes, includes the following components.
         1. Number of occupants,   2. Identity of occupants (including unrecognized) which may derive information from body, facial features, movement, etc.,   3. Body position/gesture of each occupant (e.g., standing, seated, drinking, eating,   4. Sizes of transient objects in scene,   5. Nature of transient objects in scene (e.g., television, dinner plate, laundry basket, etc.),   6. Rapidity of movement of image center of occupants as an indication of running or chaos,   7. Change in camera angle, etc.
 
Video processing techniques from various fields such as authentication, gesture control of machines, etc. may be employed in the current system according to the particular aims of the system designer.
       

   Other input devices with associated classifiers  235  apply their output signals to the event/class processor  207 . The other UI classifiers  235  may include instrumentation monitoring the environment such as ambient light level, time of day, temperature of the room, security status of a building, etc. 
   Text data may be obtained from a speech to text converter  215  which receives the audio input  245  and converts it to text. When obtained from audio, the text may be time-stamped by the speech to text converter  215 . The speech to text converter  215  parses the text using grammatical or structural rules such as used in new or prior art conversation simulators, as used in natural language search engines, or other suitable means. The result of this parsing is the extraction of words or utterance features that the mental state/health status classifier  290  may recognize. Parsing may be done using rule-based template matching as in conversation simulators or using more sophisticated natural language methods. Words indicative of mood may then be sent to the mental state/health status classifier  290  for classification of the mood of the speaker. 
   The mental state/health status classifier  290  receives signals from the various classifiers and processes these to generate a mood/personality state signal. The mental state/health status classifier  290  may be a trained neural network, a Bayesian network, a simple rule-based system, or any other type of classifier capable of taking many different inputs and predicting a probability of the occupant being in a given emotional state and having a given personality. Various personality and mood typologies may be used, running from simple to complex. An example of set of rules for classifying an occupant as bored is:
         low sentence/phrase word count (the occupant&#39;s sentences contain few words) (input parser  410  signal indicating response word count),   a low incidence of words suggesting enthusiasm such as superlatives (input parser  410  signal indicating adjectives),   a quiet flat tone in the voice (audio classifier  210  signal indicating modulation inflection intensity),   a lack of physical movement (video image classifier  240  signal indicating , etc.,   little movement of the head or body,   sighing sounds, etc.   looking at watch.   lack of eye contact with objects such as television or book in the scene.
 
Each of these may be classified by the corresponding classifier. The color of the occupant&#39;s clothes, the pitch of the occupant&#39;s voice, the number of times the occupant enters and leaves a single scene, the way the occupant gestures, etc. all may provide clues to the occupant&#39;s emotional state and/or personality. The output vector may be any suitable mental state classification. For example, the valence/intensity emotional state typology suggested in U.S. Pat. No. 5,987,415 may be used.
       

   The following tables summarize the Big Five which is an evolutionary outgrowth of the Myers-Briggs typology. There are many academic papers on the subject of modeling emotional states and personalities and many of these address the issues of machine classification based on voice, facial expression, body posture, and many other machine-inputs. Even the weather, which may be obtained using an agent over the Internet or via instruments measuring basic weather data such as daily sunshine, may be used to infer mental emotional state. 
   The Six Facets of Negative Emotionality (adapted from Costa &amp; McCrae, 1992) with Anchors for the Two Extremes of the Continuum 
                                   Six Facets of Negative   RESILIENT   REACTIVE       Emotionality   R+−   R−                   Worry   Relaxed; calm   Worrying; uneasy       Anger   Composed; slow to   Quick to feel           anger   anger       Discouragement   Slowly   Easily           discouraged   discouraged       Self-Consciousness   Hard to   More easily           embarrass   embarrassed       Impulsiveness   Resists urges   Easily tempted           easily       Vulnerability   Handles stress   Difficulty           easily   coping                    
The Six Facets of Extraversion (adapted from Costa &amp; McCrae, 1992) with Anchors for the Two Extremes of the Continuum
 
                                               Six Facets of   INTROVERT   EXTRAVERT           Extraversion   E−   E+                           Warmth   Reserved;   Affectionate; friendly,               formal   intimate           Gregariousness   Seldom seeks   Gregarious, prefers               company   company           Assertiveness   Stays in   Assertive; speaks up;               background   leads           Activity   Leisurely pace   Vigorous pace           Excitement-Seeking   Low need for   Craves excitement               thrills           Positive Emotions   Less exuberant   Cheerful; optimistic                        
The Six Facets of Openness (adapted from Costa &amp; McCrae, 1992) with Anchors for the Two Extremes of the Continuum
 
                                               Six Facets of   PRESERVER   EXPLORER           Openness   O− −   O+                           Fantasy   Focuses on here and   Imaginative; daydreams               now           Aesthetics   Uninterested in art   Appreciates art and                   beauty           Feelings   Ignores and discounts   Values all emotions               feelings           Actions   Prefers the familiar   Prefers variety; tries                   new things           Ideas   Narrower intellectual   Broad intellectual               focus   curiosity           Values   Dogmatic;   Open to reexamining               conservative   values                        
The Six Facets of Agreeableness (adapted from Costa &amp; McCrae, 1992) with Anchors for the Two Extremes of the Continuum
 
                                               Six Facets of   CHALLENGER   ADAPTER           Agreeableness   A−   A+                           Trust   Cynical;   See others as honest &amp;               skeptical   well-intentioned           Straightforward-   Guarded;   Straightforward, frank           ness   stretches truth           Altruism   Reluctant to get   Willing to help others               involved           Compliance   Aggressive;   Yields under conflict;               competitive   defers           Modesty   Feels superior   Self-effacing; humble               to others           Tender-Mindedness   Hardheaded;   Tender-minded; easily               rational   moved                        
The Six Facets of Conscientiousness (adapted from Costa &amp; McCrae, 1992) with Anchors for the Two Extremes of the Continuum
 
   
     
       
             
             
             
           
         
             
                 
             
             
               Six Facets of 
               FLEXIBLE 
               FOCUSED 
             
             
               Conscientiousness 
               C− 
               C+ 
             
             
                 
             
           
           
             
               Competence 
               Often feels 
               Feels capable and 
             
             
                 
               unprepared 
               effective 
             
             
               Order 
               Unorganized; 
               Well-organized; neat; 
             
             
                 
               unmethodical 
               tidy 
             
             
               Dutifulness 
               Casual about 
               Governed by 
             
             
                 
               obligations 
               conscience; reliable 
             
             
               Achievement Striving 
               Low need for 
               Driven to achieve 
             
             
                 
               achievement 
               success 
             
             
               Self-Discipline 
               Procrastinates; 
               Focused on completing 
             
             
                 
               distracted 
               tasks 
             
             
               Deliberation 
               Spontaneous; 
               Thinks carefully 
             
             
                 
               hasty 
               before acting 
             
             
                 
             
           
        
       
     
   
   The mental state/health status classifier  290  outputs a state vector, with a number of degrees of freedom, that corresponds to the models of personality and mental state chosen by the designer. The mental state/health status classifier  290  may cumulate instantaneous data over a period of time in modeling personality, since this is a persistent state. The mental state will have more volatile elements. 
   The event/class processor  207  is a classifier that combines state information from multiple classifiers to generate an environment/occupant state signal indicating the current status of the system&#39;s environment, including the occupants, particularly the monitored person. The event/class processor may also generate event signals (interrupt signals) to ensure an instant response when certain events are recognized by the classifiers, for example, events that may coincide with an emergency condition. The recognition of events may require state information from multiple classifiers, so the event/class processor  207  combines state data from multiple classifiers to generate a combined state signal and a combined event signal. The environment/state signal may include an indication of all the possible event classes the various classifiers are capable of identifying or only those surpassing a threshold level of confidence. 
   The output generator  415  receives the mood/personality state vector and parsed reply data from the mental state/health status classifier  290  and input parser  410  respectively. The response generator  415  also receives the environment/occupant state signal and events signal from the event/class processor  207 . The output generator  415  selects a type of response corresponding to the mental state, the environment/occupant state, and the events signal from an internal database and generates an alarm output if required. Alternatively, the output generator may be programmed to select an output template that solicits further data from an occupant through user interface, such as the terminal  116  (FIG.  1 ). For example, if the various classifier output components indicate low confidence levels, the system could generate speech through the speaker  114  asking for information about the current state of the occupied space. For example “Is anyone there” could be generated if no clear presence of an adult can be detected. The system then uses its other input devices, such as video input  255 , to decrease ambiguity in its status and event signals. Note that these features may be implemented through a conversation simulator as described in U.S. patent Ser. Nos. 09/699,606, 09/686,831, and 09/699,577 may be built into the system to operate as a machine assistant. 
   Tracing the data flow beginning with the video input  255 , the video input  255  signal is applied to the video image classifier  240 . The video image classifier  240  is programmed to recognize a variety of different image and video-sequence classes in the video input  255  signal. For example, it may be programmed to distinguish between a person sitting up and lying down; between a person sitting still and one moving agitatedly or leaving an area; etc. A probability for each of these classes may be generated and output as a signal. Alternatively, a single, most-probable class may be generated and output as a signal. This signal is applied to the event/class processor  207 , which combines this data with other class data to generate an environment/occupant state signal. If the event/class processor  207  receives an indication from the video image classifier  240  that something sudden and important has occurred, for example, the occupant has gotten up and left the room, the event/class processor  207  will generate an event signal. If the mental state/health status classifier  290  receives a signal from the video image classifier  240 , indicating the occupant is moving in a fashion consistent with being agitated, that mental state/health status classifier  290  may combine this information with other classifier signals to generate a mood/personality state vector indicating an emotional state of heightened anxiety. For example, the audio classifier  210  may be contemporaneously indicating that the speaker&#39;s voice is more highly pitched than usual and the input parser  410  may indicate that the word count of the most recent utterances is low. 
   Note that to allow the system to determine whether a current class or state represents a change from a previous time, the event/class processor  207  and the mental state/health status classifier  290  may be provided with a data storage capability and means for determining the current occupant so that corresponding histories can be stored for different occupants. Identification of occupants, as mentioned above, may be by face-recognition by means of the video image classifier  240 , voice signature. It may also be confirmed by radio frequency identification (RFID) token, smart card, or a simple user interface that permits the occupant to identify him/herself with a biometric indicator such as a thumbprint or simply a PIN code. In this way, both the mental state/health status classifier  290  and event/class processor  207  may each correlate historical data with particular occupants and employ it in identifying and signaling trends to the output generator  415 . 
   The event/class processor  207  receives class information from the audio classifier  210  and other classifiers and attempts to identify these with a metaclass it is trained to recognize. That is, it combines classes of states to define an overarching state that is consistent with that multiple of states. Of course, the architecture described herein is not the only way to implement the various features of the invention and the event/class processor  207  could simply be omitted and its functions taken over by the output generator  415 . One advantage of separating the functions, however, is that the event/class processor  207  may employ a different type of classifier than the one used by the output generator  415 . For example, the output generator  415  could use a rule-based template matcher while the event/class processor  207  could use a trained neural network-type classifier. These allocations of functions may be more suitable since the number of outputs of the output generator  415  may be much higher than the number of classes the event/class processor  207  (or the other classifiers) is trained to recognize. This follows from the fact that network-type classifiers (such as neural network and Bayesian network classifiers) are difficult to train when they have a large number of possible output states. 
   The video image classifier  240  process may contain the ability to control the cameras (represented by video input  255 ) that receive video information. The video image classifier  240  may contain a process that regularly attempts to distinguish objects in the room that may or may not be individuals and zoom on various features of those individuals. For example, every time a video image classifier identifies a new individual that image classifier may attempt to identify where the face is in the visual field and regularly zoom in on the face of each individual that has been identified in the field of view in order to obtain facial expression information which can be used for identifying the individual or for identifying the mood of the individual. 
   We note that the invention may be designed without the use of artificial intelligence (AI) technology as described above, although of robustness of AI technology makes it highly desirable to do so. For example, an audio signal may be filtered by a bandpass filter set for detection of loud crashing sounds and a detector that sets a time-latch output when the filter output is above certain level. Concurrently, a video luminance signal may be low pass filtered and when its energy goes beyond a certain level, it also sets a time-latch. If both latched signals go positive (loud sound and great activity in temporal proximity), the system may generate an alarm. 
   Alarm signals may include simply some kind of notification of an alarm status. Preferably, however, alarms should be informative as possible within the specified design criteria. For example, an alarm signal may contain audio and/or video data preceding and following the event(s) that triggered the alarm status. These could be recorded by the output generator  415  and transmitted by email, streamed through a cell-phone connection or wireless convergence device with video capability, or some other means. Symbolic representations of the most significant state classes that gave rise to the meta-classification of the alarm condition may also be transmitted. For example, a symbol indicating “loud noise” and/or unrecognized occupant may be transmitted to, say, a text pager used by a responsible party. 
   Referring now to  FIG. 4 , an arbitrary number of signals may be buffered continuously as illustrated by step S 10 . If an alarm condition is indicated, at step S 15  it is determined if the particular alarm condition had been previously overridden. If it had, buffering of signals is resumed and no further action is taken. If the alarm condition had not been overridden, a message is generated at step S 20  and the buffered signals  1  . . . N attached at step S 30 . The alarm message is then transmitted, for example by email, in step S 40  and an optional live feed generated at step S 50  if appropriate. The live feed may be made available at a URL included in an email transmission or as a portion of a signal in a message transmitted by an automated telephone call to a digital video telephone. 
   The buffered signal may be no more than a time sequence indicating the status of one or more sensors over time. The buffered signals need not be signals that caused the indication of an alarm condition. For example, in an embodiment of the invention, a video camera may be trained on a person&#39;s bed. The alarm may be generated by a mechanical sensor (such as a chest strap) that detects breathing. The video signal buffer up till the moment of the detection of the person&#39;s cessation of breathing may be the signal that is transmitted as part of the alarm message. The length of the buffer may be as desired. 
   Each alarm may be a unique event, but each may also be generated by the same persistent condition, for example a failure of an infant or child to breathe for a period of time. It is desirable for a given alarm to be acknowledged so that a new alarm condition, arising from different circumstances, is not confused as the existing alarm currently being attended to. One way to handle this is to assign a signature to each alarm based on a vector of the components that gave rise to the alarm condition. The recognition of the same alarm condition would give rise to another vector which may be compared to a table of existing alarms (at step S 15 ) to see if the new alarm had already been overriden. The components may be quantized to insure against small differences in vector components being identified as different or a low sensitivity comparison may be used to achieve the same effect. 
   Alarm signals may be transmitted by any of the following means.
         1. Automatic telephone call with synthetic voice providing symbolic indication of alarm condition (pre-recorded phrases or synthetic speech) and/or buffered audio and/or live audio fed from the monitored space.   2. Wireless appliance with video may include the above plus recorded and/or live data plus text messages providing same information.   3. E-mail message, may contain links to a URL with live or recorded data or may have embedded MIME attachment providing still or moving images.   4. Broadcast: radio message, audio message, display on a wired console, etc.       

   The following are several example applications and use scenarios. 
   EXAMPLE 1 
   An infant&#39;s crib is placed against a wall with one or more cameras  135 ,  136  aimed at a side of the crib where a caretaker would ordinarily stand to view the infant. A microphone  112  is placed in a position to pick up sounds near the crib. The controller  100  receives live video and audio signals from the camera and microphone and filters them through respective classifiers  240  and  210 , respectively. The controller  100  is programmed to recognize the caretaker&#39;s face and produces a signal indicating that a face is present and a reliability estimate indicating how well the face matches expectation. The controller  100  may be programmed to recognize other faces as well, such as relatives of the baby and children. The controller  100  is further programmed to recognize the sound of crying and produce a signal indicating that crying is present. In addition, the controller  100  is programmed to recognize the following events and produce corresponding signals: normal and abnormal body habitus of the infant, facial expression of infant indicating mood such as crying, content, playing, distressed, moving quickly or slowly, the number of individuals present, presence of new objects in the room and their “blob” sizes (“blob” is a term of art characterizing any closed connected shape that an image processor can define in a video image), mood of recognized face of caretaker. 
   In the above example, the following events may occur. The infant cries and the caretaker fails to respond. The infant&#39;s mood is detected by the audio and video signals received. A synthetic voice calls to the caretaker via the speaker  114  requesting assistance for the infant. The elapsed time from the recognition of the infant&#39;s distress till the present reaches a specified interval triggering an alarm. The alarm signal includes a text message, buffered video and buffered audio from a time prior to the alarm event. The alarm signal is sent by email. 
   EXAMPLE 2 
   The system configuration of example 1 is included in the present example. Additional cameras and microphones are located at various locations in a house. The baby&#39;s presence on a couch is detected. The caretaker is recognized on the couch. The sound of the television is detected. The body position of the adult caretaker is detected in a sleeping position. The system generates synthetic speech requesting for the caretaker to wake up and attend the infant (the programming of the controller  100  being a reflection of a concern that the infant is not in a safe place to be unattended. After a predefined interval during which continued sleep (or illness or death) is detected, an alarm is generated. The alarm contains still images from the video (from a time prior to the alarm) of the sleeping adult and infant and live audio and video of the room in which the infant and adult are located. 
   EXAMPLE 3 
   The physical configuration (including programming) of Example 2 is incorporated in the present example. In this example, the infant and crib are replaced by a sick adult and the caretaker is an adult. The supervisor is an agency that supplied the nurse. The alarm condition detected by the system is the lack of movement of any articles or persons in the house. The recognition of occupants, facial recognition, body habitus and body positions, audio, etc. are producing indications of a presence of an adult in a living room, but the signals are low reliability and there is no indication of activity (movement of the occupant). The system is programmed to generate an alarm if none of a set of expected events such as appearance of a recognized face at the bedside of the sick person, movement plus a recognized body position of a person in expected locations in a house, etc. for a predefined interval. The alarm signal contains a live video and audio feed which is controllable by the supervisor (who can switch views, etc. and communicate with the caretaker). 
   EXAMPLE 4 
   The system of Example 3 is incorporated in the present example. A babysitter is taking care of multiple children. The system is programmed to recognize the babysitter&#39;s face and the faces of the children along with various characterizing features of these people such as body shape, movement patterns, etc. The system is programmed to generate an alarm, and transmit it to a wireless handheld device, when either of the following occurs: (1) the number of occupants detected in the house (the system detects simultaneously at multiple cameras, a particular number of individuals) is greater than a predefined number (presumably the babysitter plus the children) or (2) the system detects an unrecognized face (i.e., it receives a good image of a face, but cannot produce a reliable match with a known template), (3) doors left open for extended periods of time (as indicated by security system status), (4) movement of persons in the house is excessive potentially indicating roughhousing or abuse. 
   Although in the embodiments described, the visage, location, and activities of both caretaker and person requiring care were monitored, it is possible to monitor only one or the other rather than both. Also, the notion of “occupants” recognized or not, may be applied as well to pets as to human occupants, although admittedly, the state of the art may not be at a point where pet&#39;s facial features may be distinguished from those of other animals, certainly the blob-recognition is at a point where it can distinguish between a poodle and cat or other kinds of animals and/or animate objects such as robots. 
   While the present invention has been explained in the context of the preferred embodiments described above, it is to be understood that various changes may be made to those embodiments, and various equivalents may be substituted, without departing from the spirit or scope of the invention, as will be apparent to persons skilled in the relevant art.