Abstract:
Monitoring devices by following and analyzing local current measurements and communicating the data over the power line. Various operation characteristics are extracted from the measurements, such as device profiles, operational status, various deficiencies and user related parameters. Current consumption profiles are derived from the accumulating data, and compared to previous patterns. The monitoring allows controlling operation of the devices, estimating their physical location and communicating messages from the devices regarding e.g. software status, by deliberate operation of the device to generate predefined current use patterns.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a Continuation In Part of U.S. patent application Ser. No. 12/172,235 filed on Jul. 13, 2008, which is incorporated herein by reference, and claims the benefit thereof in respect to the common subject matter. 
     
    
     BACKGROUND 
       [0002]    1. Technical Field 
         [0003]    The present invention relates to the field of monitoring, and more particularly, to monitoring of device operation. 
         [0004]    2. Discussion of Related Art 
         [0005]    Bauer et al. “Recognizing the Use-Mode of Kitchen Appliances from Their Current Consumption” in Smart sensing and context, Lecture Notes in Computer Science, 2009, Volume 5741/2009, 163-176 (DOI: 10.1007/978-3-642-04471-7 — 13) and Berges et al. “Enhancing Electricity Audits in Residential Buildings with Nonintrusive Load Monitoring”, Journal of Industrial Ecology, Special Issue: Environmental Applications of Information &amp; Communication Technology. Volume 14, Issue 5, pages 844-858, October 2010, both incorporated herein by reference in their entirety, disclose systems for monitoring instrument loads. 
       BRIEF SUMMARY 
       [0006]    Embodiments of the present invention provide A system for monitoring a plurality of devices, comprising: a control unit; and associated with each device: a current meter arranged to measure a current used by the device; and a PLC unit arranged to send a device identifier and data relating to the current measurements to the control unit over power line communication (PLC), wherein the control unit is arranged to analyze the current measurements and derive device operation characteristics therefrom. 
         [0007]    These, additional, and/or other aspects and/or advantages of the present invention are: set forth in the detailed description which follows; possibly inferable from the detailed description; and/or learnable by practice of the present invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    The present invention will be more readily understood from the detailed description of embodiments thereof made in conjunction with the accompanying drawings of which: 
           [0009]      FIG. 1  is a high level schematic block diagram of a system for monitoring a plurality of devices, according to some embodiments of the invention; 
           [0010]      FIGS. 2 and 3  are examples for current measurements and the information derived from them, according to some embodiments of the invention; 
           [0011]      FIG. 4  is a high level flowchart illustrating a method of monitoring devices according to some embodiments of the invention; and 
           [0012]      FIG. 5  illustrates a method for controlling a usage of objects, according to an embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0013]    Before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of the components set forth in the following description or illustrated in the drawings. The invention is applicable to other embodiments or of being practiced or carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein is for the purpose of description and should not be regarded as limiting. 
         [0014]      FIG. 1  is a high level schematic block diagram of a system  100  for monitoring a plurality of devices  90  according to some embodiments of the invention. System  100  comprises a control unit  110  connected over power line  96  to devices  90 , and current meters  122  and PLC units  124  associated with each device  90 . Current meters  122  and PLC units  124  may be integrated within devices  90  or connected to devices  90  internally or externally. 
         [0015]    Current meter  122  is arranged to measure a current used by device  90  and PLC unit  124  (e.g. a PLC modem) is arranged to send a device identifier and data relating to the current measurements to control unit  110  over power line communication (PLC). Control unit  110  is arranged to analyze the current measurements and derive device operation characteristics therefrom. 
         [0016]    Device ( 90 ) operation characteristics may comprise characteristics relating to device profile, characteristics relating to momentary device performance, as well as characteristics relating to defects and malfunction of device  90 . Device operation characteristics may comprise for example a device type, an operational state of device  90 , a deterioration in device operation, a device malfunction, an improper operation of device  90 , a loading status of device  90 , and an cumulative usage time of device  90 . 
         [0017]    Device operation characteristics may comprise a current consumption profile of each device  90  at a specified temporal resolution, or as indications of specified state or changes between states of device  90 . Control unit  110  may be further arranged to generate statistical data from obtained current measurements and use the statistical data as a basis for comparison for future measurements. Control unit  110  may store the statistical data in a database  114 . 
         [0018]    For example, system  100  may detect damaged contacts in device  90  by detecting a reduction in current consumption of device  90 , system  100  may identify loaded devices by comparing their current consumption with a given maximal current consumption, and system  100  may identify devices  90  in their initialization stages by detecting a specified current increase during a specified period. System  100  may further discriminate active from idle devices  90  according to specified ranges of current measurements. System  100  may identify improper operation of device  90  by identifying unexpected changes in current measurements. 
         [0019]    A device type may be derived from typical current consumption data in relation to statistical data, the operational state of device  90  (on, off, standby, rotation, stage of operation, active components etc.) may be derived in relation to earlier operation patterns. A deterioration in device operation may be detected in relation to earlier data. Improper operation of device  90  may be detected in relation to given criteria or specifications. 
         [0020]    The data relating to the current measurements may comprise various derivatives of the current measurements, that are usable to reduce the necessary communication bandwidth. Such derivatives may comprise current idle consumption, current peaks, current drops, and current derivatives. As the PLC network bandwidth is limited and is shared with all devices  90 , it may not allow to send the current measurements in high sampling rate. Therefore, the data relating to the current measurements may only comprise the most relevant data (for the derivation of the device operation characteristics), possibly as tags. 
         [0021]    At least one of devices  90  may further comprise a processor  128  arranged to derive the data relating to the current measurements from the current measurements to comprise operation relevant data, such that the data relating to the current measurements has a smaller size than the current measurements, selected to allow communication of the data over PLC during a specified threshold period. 
         [0022]    Control unit  110  may be further arranged to prevent supply of power to a device  90  upon receiving specified current measurements therefrom, according to specified criteria. For example, devices  90  that are being improperly operated may be disconnected and checked, or user identification may be controlled. 
         [0023]    System  100  may further comprising a plurality of repeaters  95  arranged to enhance PLC signals from PLC units  124  to control unit  110 . Each repeater  95  has an identifier and a physical location, and is arranged to add to the enhanced PLC signals its identifier. Control unit  110  is further arranged to estimate from the repeater identifiers received with each enhanced PLC signals, a physical position of a corresponding device  90 , in respect to the physical locations of identified repeaters  95 . 
         [0024]    At least one device  90  may further comprise a communication unit  132  in wireless communication via a communication link  99  with control unit  110 , with other devices  90 , or with a communication unit  133  operating as a network bridge, and having an identifier and a physical location, which may be used similarly to those of repeaters  95 . Control unit  110  and device  90  may be arranged to communicate through various communication links  99 , and are not limited to PLC communication. 
         [0025]    Communication unit  132  is arranged to send the data relating to the current measurements from device  90  for communication to control unit  110  (either directly or via PLC unit  124  of communication unit  133 . Communication unit  132  thus enables extending the described system  100  to monitor devices  90  that are not directly connected to power line  96 . 
         [0026]    Device operation characteristics may comprise an update status of software installed on device  90 . Control unit  110  may be arranged to derive the update status by detecting a predefined pattern of current consumption associated with the software update, for example alternately turning on and off a current consuming component in device  90 , such as a display, loudspeakers, a modem, solenoids, heating elements or motors (e.g. servo motors). These features allows control unit  110  to supervise the software update status of all devices in the network. 
         [0027]    Device  90  may comprise an encoder  126 , arranged to encode specified device parameters into an operational sequence of device components, to yield an specified pattern of current measurements (e.g. a sequence of high and low current consumption periods). Control unit  110  may comprise a decoder  112  arranged to derive the specified device parameters from the received specified pattern of current measurements. Such a coding allow communicating messages between device  90  and control unit  110  on the basis if system  100 , without addition of a dedicated communication system. 
         [0028]    In embodiments, device  90  with a low current consumption, or device  90  that is sensitive to re-occurring current consuming operations, may cause (e.g. via PLC or communication link  99 ) another device to encode the message with its own current consumption, including a signal denoting the sender of the message as the relevant device  90 . 
         [0029]    Encoding messages by current consumption patterns allows control unit  110  call for data from devices  90  (data such as software update status), and enables devices  90  respond only by changing their current consumption according to a predefined code (e.g. a Morse code). 
         [0030]    Furthermore, control unit  110  may prevent power supply to devices  90  that have not responded, or report devices  90  which were not updates, and system  100  thus allows efficient monitoring not only of the operational states of devices  90 , but also of software parameters and other data which do not reflect in current consumption. 
         [0031]    Elements such as encoder  126 , communication unit  132  and processor  128  may be integrated within devices  90  or connected to devices  90  internally or externally. 
         [0032]      FIGS. 2 and 3  are examples  150  for current measurements and the information derived from them, according to some embodiments of the invention. Examples  150  are experimental results that relate to device  90  having a pump, such as an infusion or dialysis device. Examples  150  depict current measurements by current meter  122  along time. 
         [0033]    Example  150  in  FIG. 2  illustrates the differences in current consumption in various states of device  90 : disconnection ( 152 ), connection and device turned off ( 154 ), device turned on ( 156 ) and operation of the pump ( 160 ). Data sent to control unit  110  may comprise all or some of the measurement, averaged measurements, or device states themselves as analyzed by processor  128 . 
         [0034]    Example  150  in  FIG. 3  illustrates the detection of improper operation of device  90 , identified upon a sequence of turning device  90  on ( 152 ) and off ( 154 ), and alternating operation of the pump ( 160 ) at maximal ( 162 ) and intermediate ( 164 ) intensities. This type of sequences may be identified by control unit  110  as indicating improper operation of device  90 , and may be followed by preventing power supply to device  90 , checking the problem, teaching the user how to properly operate device  90 , etc. 
         [0035]    The clear differences in measured current in different operational states of device  90  also allow communicating various short messages from device  90  to control unit  110 , using current measurements to encode predefined parameters, such as software update versions. By operating device  90  in a specified operation pattern of current consuming components, short messages may be identified by decoder  112  in control unit  110 . 
         [0036]      FIG. 4  is a high level flowchart illustrating a method  200  of monitoring devices  90  according to some embodiments of the invention. Method  200  may comprise the following stages: measuring, locally and continuously, a current used by each device (stage  205 ), communicating a device identifier and data relating to the current measurements over power line communication (PLC) (stage  210 ), analyzing the current measurements (stage  215 ) and deriving device operation characteristics from the analyzed current measurements (stage  220 ), e.g. to reduce a PLC communication volume. Only derived essential operation characteristics may be communicated (stage  245 ) to use the available bandwidth economically. At least one of stages  215  and  220  is carried out by at least one processor. 
         [0037]    Method  200  may further comprise generating statistical data from obtained current measurements (stage  225 ) and comparing the current consumption to statistical data (stage  230 ), to yield device operational parameters. 
         [0038]    Method  200  may further comprise preventing supply of power to at least one of the devices upon receiving specified current measurements, according to specified criteria (stage  235 ) relating e.g. to proper operation patterns or to authorized actions in relation to device users. 
         [0039]    Method  200  may further comprise using repeater to enhance the PLC signals and estimating from repeater identifiers received with repeater-enhanced PLC signals, a physical position of a corresponding device, in respect to the physical locations of the identified repeaters (stage  240 ). 
         [0040]    Method  200  may further comprise encoding specified device parameters into an operational sequence of device components (stage  260 ), to yield an specified pattern of current measurements, and deriving the specified device parameters from the received specified pattern of current measurements (stage  265 ). Encoding (stage  260 ) may comprise alternately turning on and off a current consuming component in the device (stage  250 ) or in another device. Encoding  260  may utilize any code, for example a Morse code. The specified device parameters may comprise a software update status, and deriving (stage  265 ) may comprise deriving a software update status by detecting a predefined pattern of current consumption associated with the software update (stage  255 ). Method  200  thus allows a control unit call for data from the devices (such as software update status), and enables the devices respond only by changing their current consumption according to a predefined code. 
         [0041]      FIG. 5  illustrates method  500  for controlling a usage of objects, according to an embodiment of the invention. Method  500  may be implemented by a power controller such as current meter  122  and PLC unit  124 . 
         [0042]    Method  500  starts by stage  510  of detecting that the power controller is connected to a power supply network, after being disconnected from the power supply network. The power controller is associated with an object such as device  90 . The object can be used only if it is connected (via the power controller) to the power supply network. 
         [0043]    Stage  510  is followed by stage  520  of transmitting, to a control unit, over a PLC network and from a power controller associated with the object, a request to determine whether to enable the object to receive power from the power supply network. 
         [0044]    Stage  520  is followed by stage  530  of receiving, over the PLC network, a power indication representative of the determination of the control unit. 
         [0045]    Stage  530  is followed by stage  540  of selectively providing power to the object in response to the determination of control unit  110 . Accordingly, the object received power from the power supply network only of authorized to do so by control unit  110 . 
         [0046]    Method  500  can include at least one of the following optional stages or a combination thereof: (i) stage  550  of monitoring the power consumption of the object; (ii) stage  560  of sending to control unit  110 , over the PLC network, information relating to the power consumption of the object; (iii) stage  570  of transmitting to control unit  110 , over the PLC network, location information, and (iv) stage  580  of generating an exit indication if sensing that the object is about to exit a predefined premises. 
         [0047]    In the above description, an embodiment is an example or implementation of the invention. The various appearances of “one embodiment”, “an embodiment” or “some embodiments” do not necessarily all refer to the same embodiments. 
         [0048]    Although various features of the invention may be described in the context of a single embodiment, the features may also be provided separately or in any suitable combination. Conversely, although the invention may be described herein in the context of separate embodiments for clarity, the invention may also be implemented in a single embodiment. 
         [0049]    Furthermore, it is to be understood that the invention can be carried out or practiced in various ways and that the invention can be implemented in embodiments other than the ones outlined in the description above. 
         [0050]    The invention is not limited to those diagrams or to the corresponding descriptions. For example, flow need not move through each illustrated box or state, or in exactly the same order as illustrated and described. 
         [0051]    Meanings of technical and scientific terms used herein are to be commonly understood as by one of ordinary skill in the art to which the invention belongs, unless otherwise defined. 
         [0052]    While the invention has been described with respect to a limited number of embodiments, these should not be construed as limitations on the scope of the invention, but rather as exemplifications of some of the preferred embodiments. Other possible variations, modifications, and applications are also within the scope of the invention. Accordingly, the scope of the invention should not be limited by what has thus far been described, but by the appended claims and their legal equivalents.