Abstract:
The presence of a child within an enclosed space in an appliance, such as a washing machine, dishwasher or refrigerator, is detected using one or more MEMS sensors positioned to detect movement within the enclosed space through various measured characteristics. In preference, combinations of different types of MEMS sensors are utilized to detect the movement. Movement may be attributed to the presence of a child inside the enclosed space, rather than resulting from other influences, with increased reliability if the determination is made based upon such combinations of different characteristics. Safety processes may be initiated upon detecting the presence of the child.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority as a continuation-in-part of U.S. patent application Ser. No. 12/916,206 filed Oct. 29, 2010 and entitled “SYSTEM AND METHOD TO DETECT CHILD PRESENCE.” The content of the above-identified patent document(s) is hereby incorporated by reference. 
     TECHNICAL FIELD 
     Generally, the present disclosure relates to detecting the presence of a child in enclosed areas such as the wash drum of a washing machine or the interior of a refrigerator. 
     BACKGROUND 
     Many homes, offices, and buildings contain machines, such as refrigerators and washing machines, which have confined areas with doors that are secured or even sealed by automatic latching (mechanical, magnetic, etc.). Children, particularly small children, are known to explore and climb into such confined areas, which may result in serious injury or death if the child becomes trapped inside for an extended period of time or if the machine is activated while the child in within the machine. 
     Accordingly, there is a need in the art to detect the presence of a child within a confined area of a machine and to prevent activation of the machine while a child is inside. 
     SUMMARY 
     The presence of a child within an enclosed space in a machine, such as a washing machine, dishwasher or refrigerator, is detected using one or more MEMS sensors positioned to detect movement within the enclosed space through various measured characteristics. In preference, combinations of different types of MEMS sensors are utilized to detect the movement. For instance, movement may be attributed to the presence of a child inside the enclosed space rather than other factors with increased reliability if the determination is made based upon whether shifts in the center of gravity for a load supported inside the machine coincide with noise emanating from the interior of the enclosed space. 
     Before undertaking the DETAILED DESCRIPTION below, it may be advantageous to set forth definitions of certain words and phrases used throughout this patent document: the terms “include” and “comprise,” as well as derivatives thereof, mean inclusion without limitation; the term “or,” is inclusive, meaning and/or; the phrases “associated with” and “associated therewith,” as well as derivatives thereof, may mean to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have, have a property of, or the like; and the term “controller” means any device, system or part thereof that controls at least one operation, such a device may be implemented in hardware, firmware or software, or some combination of at least two of the same. It should be noted that the functionality associated with any particular controller may be centralized or distributed, whether locally or remotely. Definitions for certain words and phrases are provided throughout this patent document, those of ordinary skill in the art should understand that in many, if not most instances, such definitions apply to prior, as well as future uses of such defined words and phrases. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a more complete understanding of the present disclosure and the advantages thereof, reference is now made to the following brief description, taken in connection with the accompanying drawings and detailed description, wherein like reference numerals represent like parts: 
         FIG. 1  is a block diagram of one system implementing child detection within an enclosed space of a machine according to one embodiment of the present disclosure; 
         FIG. 2  is a high level flowchart of a safety process for detecting presence of a child within an enclosed space of a machine according to one embodiment of the present disclosure; 
         FIG. 3  is a high level flowchart of an alternate safety process based upon detecting presence of a child within an enclosed space of a machine according to another embodiment of the present disclosure; 
         FIG. 4  is a high level flowchart of an alternate safety process based upon detecting presence of a child within an enclosed space of a machine according to yet another embodiment of the present disclosure; 
         FIG. 5  is a block diagram of a second system implementing child detection within an enclosed space of a machine according to an embodiment of the present disclosure; and 
         FIG. 6  is a block diagram of a third system implementing child detection within an enclosed space of a machine according to an embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
       FIGS. 1 through 6 , discussed below, and the various embodiments used to describe the principles disclosed in this patent document, are by way of illustration only and should not be construed in any way to limit the scope of the disclosure. 
     Detection of a child in a confined area using a child detection system (CDS) may detect the presence of a child through motion translated into an electrical signal by at least one motor or one or more sensors. By detecting the electrical signal, a user may be alerted to the presence of a child in a machine. 
       FIG. 1  is a block diagram of one system of implementing a child detection system (CDS) detecting the presence of a child in an enclosed spaced within a machine according to one embodiment of the present disclosure. System  100  includes an activation console  102  that electrically communicates via control signals with an engine or electric motor  104 , which in turn is coupled to a device associated with or within an enclosed space  106  within the machine. During operation of the system  100 , the activation console  102  is normally used to selectively activate the electric motor  104  to drive some mechanical device within the machine. Thus, the electric motor  104  may be coupled to the enclosed space  106  by a belt passing through or around a portion of the enclosed space  106 , by projection of a portion of the drive shaft of the electric motor  104  into the enclosed space, or by some other mechanical drive linkage. In one illustrative embodiment, machine  100  is a washing machine with a wash cylinder forming the enclosed space  106 , where the wash cylinder or drum is rotated by the electric motor  104 . In another illustrative embodiment, machine  100  is a dishwasher with a rotating sprayer within the enclosed space  106  that is rotated by the electric motor  104 . It is desirable to avoid activating the electric motor  104  when a child (or, equivalently, a small animal) is located within the enclosed space  106  of the machine  100 . Detection of the child within the enclosed space  106  of a machine  100  prior to activation of the electric motor  104  may prevent significant harm from occurring to the child. 
     In the exemplary embodiment of a washing machine, movement of the child within the enclosed space  106  formed by the wash cylinder is mechanically transferred to and causes motion within the electric motor  104 . Since electric motors also function as electric generators, mechanical movement of the wash cylinder in response to the child shifting therein is thus transformed into at least one electrical signal that may be detected at the activation console  102 . Similarly, in the exemplary embodiment of a dishwasher, movement by the child within the enclosed space  106  may cause movement of the rotating sprayer, which movement is transferred to and causes motion within the electric motor  104 . By detecting the presence of the child based on motion within the enclosed space  106 , a user of the machine  100  may be alerted to the presence of the child, for example, by sounding an acoustic alarm device (not shown) within the activation console  102  and/or flashing or otherwise activating one or more lights (also not shown) forming part of the activation console or otherwise visible from the exterior of the system  100 . 
     In the example shown in  FIG. 1 , activation console  102  is intended to refer to any device that may be used to engage electric motor  104  into an operational state, to impart kinetic (mechanical) energy to a device associated with or within the enclosed space  106 . Activation console  102  may comprise one or more input devices and one or more screens that display the operational status, information, or other items related to the machine  100 . 
     Electric motor  104  in the example of  FIG. 1  is intended to refer to any device capable of generating kinetic energy and transferring that energy to the machine associated with or within the enclosed space  106 , and that is conversely capable of detecting the transfer of kinetic energy to that machine from within enclosed space  106 . Examples of the electric motor  104  include, but are not limited to, an electromagnetic motor configured to transform an electric current into rotational kinetic energy. In one embodiment, during a period in which electric motor  104  is not in an active state as determined by the control signals from activation console  102 , kinetic energy or movement within the enclosed space  106  is mechanically transferred into the electric motor  104 , as by movement of a belt or other drive linkage between the electric motor  104  to the machine associated with or within enclosed space  106  (e.g., rotation or other shifting of the wash cylinder) or by direct rotation of the drive shaft of the electric motor  104  (e.g., by movement of the rotating sprayer). 
     The machine associated with or within the enclosed space  106  may be any device, apparatus, or unit that accepts mechanical drive force from the electric motor  104 . Examples of such mechanical drive force input include kinetic energy in the form of motion from an apparatus such as the wash cylinder and a connecting belt in a washing machine or a rotating sprayer in a dishwasher. 
     Those skilled in the art will recognize that the complete structure of a machine including an enclosed space posing a danger to children is not depicted in the drawings, and that the full details of operation of such a machine are not described. Instead, for simplicity and clarity, only so much of such a machine as is either unique to the present disclosure or necessary for an understanding of the present disclosure is depicted and described. 
       FIG. 2  is a high level flowchart of a safety process based upon detecting presence of a child within an enclosed space of a machine according to one embodiment of the present disclosure. The process  200  is preferably implemented within the machine controller  108  or similar control system of the machine  100  including an enclosed space  106 , such as within the controller  108  mounted within the activation console  102  for system  100  and coupled to electric motor  104 , generating control signals for starting and stopping operation of electric motor  104 . In the exemplary embodiment illustrated  FIG. 2 , user activation of a user control to initiate operation of the machine is detected (step  202 ) and a check is made to determine whether motion has been detected inside the machine (step  204 ) since the machine was last operational. For example, the monitoring system electrically coupled to the electric motor  104  may set a flag if, at any time between the machine ending a last operational cycle and user activation of the control to start another operational cycle of the machine, movement within the enclose space  106  of the machine is detected based on current received from the electric motor  104 . Current or another electrical signal output from the electric motor  104  may reflect that motion occurred in the enclosed space. 
     If monitoring for motion within the enclosed space of the machine (step  206 ) was detected at any time during the monitoring period (which may be all or any part of the time since the machine was last operational), the electric motor  104  is inhibited from being activated. If the motor  104  is inhibited from being activated or the system  100  is otherwise inhibited from being activated or engaged (step  208 ), operator intervention may be required (step  210 ) to “unlock” the machine  100  and resume operational status. The operator may be required to perform a predefined routine to restart the machine  100  (step  212 ), such as checking the interior of the enclosed space  206  as determined by opening and closing a door on the machine (detected using a door sensor, not shown) or manually canceling the activation of the machine  100  and re-initiating operation, to override the safety block resulting from detection of motion within the machine. If no motion was detected in the enclosed space  106  of the machine  100  during the monitoring period, the machine  100  is allowed to be activated or engaged (step  214 ) and a corresponding update is displayed on the activation console  102  (step  216 ). 
       FIG. 3  is a high level flowchart of an alternate safety process based upon detecting presence of a child within an enclosed space of a machine according to another embodiment of the present disclosure. Where process  200  is implemented within a machine controller  108  for the system  100 , process  300  may be performed by a controller  110  or control system within or associated with the electric motor  104  (that is, a control system responding to switching signals to connect and disconnect various circuits within the electric motor  104 ). Thus, process  300  may be used separately from or in addition to process  200  within a particular system  100 . 
     In process  300 , monitoring of the motor for current caused (for example) by electromotive force produced by mechanical rotation of the motor&#39;s drive shaft is initiated (step  302 ). Such monitoring may be initiated, for instance, upon completion of a prior operating cycle for the machine  100  —that is, the machine controller (not shown) may signal the motor control system to initiate monitoring upon completion of the prior operational cycle for the machine. 
     As long as no current within the electric motor  104  is detected, indicating movement of the motor by an external force, the monitoring process continues. If current is detected within the motor  104  (step  304 ), that subsequent motor operation is restricted (step  306 ). For example, operation of the motor may be prevented or inhibited until a clearing signal is received by the motor controller  110  (for example, from the machine controller  108 ). 
       FIG. 4  is a high level flowchart of an alternate safety process based upon detecting presence of a child within an enclosed space of a machine according to yet another embodiment of the present disclosure. The process  400  is substantially similar to the process  300  illustrated in  FIG. 3 , with the addition of allowing manual override of a motor lock after the restriction of motor operation. Manual override may be provided, for example, by a user accessible switch (not shown) within the activation console that is directly connected to the motor  104 . If a manual override is provided, upon restriction of the motor operation (step  306 ) the process begins polling for activation of the manual override (step  402 ). A particular set of actions may be required for the manual override, such as activation of a preset combination of user input buttons or keys at the activation console  102 , including activation concurrently or in a predetermined sequence. The manual override allows operation (step  404 ). Alternatively, or in addition thereto, a door to the enclosed space  106  may need to be opened and closed prior to the motor being re-enabled. 
       FIG. 5  is a block diagram of a second system implementing child detection within an enclosed space of a machine according to an embodiment of the present disclosure. The system  500  is substantially similar to the system  100  of  FIG. 1 , but with the further inclusion of one or more sensor(s)  502  connected to the activation console  102  and monitoring a portion of the enclosed space  106  (or a device associated with or within that space). Sensor(s)  502  may be either passive or active (or a combination of active and passive sensors), and may be any device capable of generating an electrical current or other signal based upon the detection of force or energy (including without limitation vibration, temperature, and air pressure). For example, the sensor  502  could be a passive pressure sensor located inside a refrigerator, washing machine, dishwasher, etc., and may be either a single large-area sensor or an array of coordinately operated sensors at various locations on interior surfaces of the enclosed space  106 . In either case, the pressure sensor(s) are used to detect changes in pressure at various locations that would be caused by movement of a child inside the enclosure, and to pass an electrical signal to the activation console  102 . Alternatively, the sensor(s)  502  may include in any combination of temperature sensor(s), accelerometer(s), one or more gyroscopes, infrared light emitter(s) and/or detector(s), or acoustic sensor(s) (i.e., microphone), or any of the sensors discussed herein. The sensor(s)  502  are configured and controlled to detect movement within the enclosed space  106  and/or the presence of an object with temperature in the range of human temperatures within the enclosed space  106 . Those skilled in the art will understand that the particular sensors utilized will depend on the nature of the machine  100 , since (for example) temperature sensors may be appropriate for refrigerators but not dishwashers. The activation console  102  may receive the signal and inhibit activation, or allow activation, as appropriate. 
       FIG. 6  is a block diagram of a third system implementing child detection within an enclosed space of a machine according to an embodiment of the present disclosure. System  600  is similar to systems  100  and  500 , but includes sensor(s)  602 . As shown, sensor(s)  602  may be mounted on or within the activation console  102  and/or the electric motor  110 . Preferably, however, at least some sensor(s)  602  are mounted within or in association with the enclosed space  106  (e.g., on walls for the enclosure). 
     Sensor(s)  602  are preferably one or more micro electro-mechanical system (MEMS) switches, configured to sense one or more of pressure (either due to direct physical forces or of air pressure), vibration or shock (acceleration), acoustic events, and temperature. MEMS sensors  602  are configured to monitor conditions inside the enclosed space of the machine  600  and to each generate an electrical signal to the machine controller  108  within the activation console  102 . The machine controller  108  employs MEMS sensors  602  to detect machine conditions that indicate the presence of a child within the enclosed space  106 . 
     The particular type and arrangement of MEMS sensors  602  within machine  600 , and the programming of machine controller  108  based upon signals from the MEMS sensors  602 , will necessarily depend upon the nature and function of the machine  600 . For example, pressure-sensitive MEMS sensors  602  positioned within vertical supports for the cabinet of a refrigerator would allow the machine controller  602  to monitor for movement within the interior of the enclosure by changes in the distribution of pressures (resulting from movement of a child&#39;s weight within the enclosed space), with the machine controller  108  determining whether shifts in pressure indicate presence of a child within the enclosed space by the regularity/variability of the pressure changes or the direction of movement indicated by such changes. A two-dimensional array of temperature-sensitive MEMS sensors  602  could monitor the interior of the refrigerator for movement of relatively “warm” spots while the refrigerator door is closed, with the machine controller  108  determining whether shifts in the location of warm spots indicate presence of a child within the interior of the refrigerator based upon the speed of movement and other factors. One or more vibration-sensitive MEMS sensors  602  could monitor for vibrations consistent with impact due to movement of a child within the refrigerator enclosure, with the machine controller  108  allowing for levels of background vibration while a compressor for the refrigeration system is running. Acoustic-sensitive MEMS sensors  602  may monitor for noise, with the machine controller  108  identifying the source of the noise and ascertaining regularity or irregularity to determine whether the noise indicates the presence of a child inside the refrigerator. 
     In each of the above cases, changes detected by MEMS sensor  602  may be qualified and/or disregarded, or filtered, based on whether the door to the enclosed space  106  is open or closed at the time the changes are detected. Thus, for example, a change in the center of gravity for the load supported by a refrigerator&#39;s internal frame need not be considered indicative of the presence of a child inside the refrigerator while the door is open (which might be due to items being placed inside), unless such changes continue after the door is closed. Further, the reliability of a determination may be considered increased when combinations of more than one indicator is detected, such as when detected changes in the center of gravity for the load supported inside a refrigerator while the door is closed coincide with detection of noise emanating from the interior of the refrigerator. 
     It should be noted that steps  204  and  206  in  FIG. 2  may be performed by reading signals from the MEMS sensors  602 , and determining whether motion within the machine is detected based on such signals. In such a case, motion inside the enclosed space may be determined directly from movement of warm spots or the emanation of noise from the interior, or indirectly from pressure (center of gravity) shifts or vibrations. 
     It should also be noted that a variety of actions may be initiated by or within the machine in addition to or in lieu of steps  208 ,  210  and  212  in  FIG. 2 . For example, merely inhibiting operation of a motor may be insufficient to protect a child trapped within the enclosed space of the machine. As noted above, audible and visual warning indicators may be activated until disabled by the user. In addition, a latching mechanism for securing closure of the door to the enclosed space may be electronically opened. In the case of a refrigerator, an electromagnet repelling the magnetic seal of the door may be activated to cause the door to open. 
     It should be understood that although an exemplary implementation of one or more embodiments of the present disclosure are illustrated in the drawings and described above, the principles of the present disclosure may be readily implemented or adapted using any number of currently known techniques. The present disclosure should in no way be limited to the exemplary implementations, drawings, and techniques illustrated and described herein, including the exemplary design and implementation illustrated and described herein, but may be modified within the scope of the appended claims along with their full scope of equivalents.