Not Applicable
Not Applicable
The present invention is in the technical field addressing applications of sensors. More specifically, this invention discloses the employment of one or more sensors, digital processing systems and storage or communications devices to efficiently and securely collect and manage data flow over a network of distributed sensors.
The data collected by a network of sensors can be used to better understand the dynamics and operations of the structure or system on which this sensor network is attached. As the number of sensors increase, the potential amount of data flowing can impose unwanted latencies in delivery or economically unappealing increases in the cost of the communications networks. Additionally, data collected by this sensor network can be used to control various operations in the system to enhance the economic efficiency of the system on which this sensor network is attached. In order to protect the operations of the system, it may be desirable to encrypt the data to protect un-authorized use. Furthermore, other desirable features and characteristics of the embodiments presented here will become apparent from the subsequent detailed description taken in conjunction with the accompanying drawings and this background.
The present invention employs an array of sensors, microprocessors, storage media and communications systems to efficiently and securely collect data from a network of sensors.
Various embodiments will hereinafter be described in conjunction with the following figures, wherein like numerals denote like elements, and
The following detailed description is merely exemplary in nature and is not intended to limit the scope or the application and uses of the described embodiments. Furthermore, there is no intention to be bound by any theory presented in the preceding background or the following detailed description.
Referring now to the invention,
While not illustrated in
These sensors 100 may consist of accelerometers, gyroscopes, pressure, acoustic, temperature, magnetic, optical, torsion, tension, force or other such measures of motion, applied forces and deformation. These sensors 100 may be arranged in any number of combinations, structures and relationships. The communications buses may be any of a number of methods currently available or that may become available in the future. The methods taught in this patent are substantially independent of the specific sensors employed, the bus and communications details.
Data generated by this sensor network and passed to the central processing system 180 may be used immediately for various purposes, stored for later use in data storage 190 and/or communicated to other systems via communications system 185.
The example of
Reconsider the sensor array illustrated in
With reference to
Now consider
As illustrated in
This process is also illustrated in
It is assumed in this simple example that the physical sensing regions of each sensor node are substantially non-overlapping. As a result, the time periods at which each sensor node requires a higher data rate are substantially non-overlapping. The data collected, generated and forwarded by sensor node A can be plotted as in line 440 in
From a systems perspective, there are multiple ways to effectively utilize available data communications bandwidth in order to maximize the quality of the data transferred through the sensor network. One basic technique is to dynamically allocate additional bandwidth to the sensor nodes generating an increased data rate and reduce the allocated bandwidth to sensor nodes not requiring the increased data rate. Taught in this patent disclosure is the process of monitoring changes in data transmission requests and by exploiting knowledge concerning the physical layout of the sensor network, the structure to which the sensor network is attached and the processes the sensor nodes are monitoring, to predictively allocate and de-allocate bandwidth to sensors as the need arises.
As illustrated in
Many other types of events are possible in a system. In some cases, these events will start as localized disturbances, (a wrench dropped on a pipe, a box of product slipping off a conveyor belt) which propagates through the physical structure. As this event propagates through the system, various sensors will detect the generated signals. Networks are typically designed with some margin to accommodate these transient signals. As the event reaches various sensors, these sensors temporarily ramp up to a higher data rate for the time while the event is detectable by the sensor and then the sensor drops back to the lower data rate. In a top-down management system, the central processing system can monitor the propagation of this event, and knowing the physical structure and dynamics of the combined structure and sensor network, predict propagation of the event and appropriately schedule data bandwidth on various sensors and buses as the event moves through the system. In a decentralized approach, the various sensors may have to negotiate data rate with neighboring sensors based on some set of commonly known rules.
Another method employed for effective utilization of network bandwidth is the use of data compression schemes. As a general rule, compression methods are either lossy or lossless. In the lossless case, an exact reproduction of the original data can be recovered from the compressed data stream. With lossy compression methods, the signal recovered from the compressed data stream will represent the original signal in specific statistical or dynamic measures and will not necessarily be an exact reproduction. Clearly, either of these data compression methods can be used with the sensors in these networks to aid in the reduction of bandwidth requirements. In a simple case of employing a 4:1 lossless compression scheme on all sensors, all the time, an approximate 4X improvement in communications efficiency can be realized. This can be used to either increase the number of sensors on a given bus, enable the use of a lower bandwidth and typically less expensive bus or some combination of both.
A more effective technique is to combine the predictive bandwidth allocation methods taught in previous paragraphs, with compression. In application of these concepts to a sensor network, the bandwidth allocation mechanism now has an additional lever to work with in the allocation of system bandwidth. By altering the compression rates (and quality of the represented data) employed at various sensor nodes to communicate the data collected at these various nodes, significant additional bandwidth can effectively be created in a network. As a general rule, lossy compression methods provide substantially larger compression rates than lossless. As an aid in explanation, assume a lossless compression rate of 4:1 and a lossy compression rate of 20:1. The specific compression schemes employed are not critical to the intent of this patent. Specific compression rates may vary considerably from the example rates employed in this discussion.
In the example of
In an alternate philosophy, the assumption is made that large changes in signal dynamics are easy to measure and making “small” errors in the estimation of these large changes has little impact on tracking and recording the properties of the event that is propagating through the sensor network. A lossy compression method can be employed and still preserve the essential information of the event. On the other hand, monitoring the steady-state signal characteristics may well depend on accurately reporting details of the small signal dynamics and may require a high-fidelity lossless compression scheme in order to preserve the details in these steady-state signals. This is compression philosophy case 2. The point of this discussion is to illustrate that depending on the specific details of the signals to be communicated, either a lossy or lossless compression technique may be employed to compress sensed measures of the event signal as it propagates through a system measured with sensors. Lossy or lossless compression methods may be required to compress the steady-state signals. Additionally, the same lossy or lossless scheme may be employed on all signals at all times.
Assume a 20:1 compression rate for the lossy method and 4:1 compression rate for the lossless method. Further assume only one sensor at a time experiences the dynamic change (event) in signal statistics as this propagates through the system. In case 1: Lossless compression is used for the event as it propagates through the systems and and lossy compression techniques are employed for the steady-state condition. Reconsider the four sensor example in
Under steady-state conditions, all sensors in the network are employing a 20:1 (lossy) compression rate and the total data rate on bus 220 in
Assuming case 2, lossless for the steady-state condition and lossy for the dynamic change, the system maintains an average 4:1 compression rate during steady-state operations. In this mode, the 3 sensors generate 3Y bps/4 or 0.150X bps. With one sensor responding to a dynamic change, the total rate on the bus is X bps/20+2Y bps/4=0.150X bps. The average rate has not changed. In this case, 39 sensors could be placed on bus 220 before exceeding the 2X bps maximum data rate. Clearly the combination of system wide data rate or bandwidth management combined with compression schemes can provide large increases in the number of sensors deployable on a given communications bus. It is also obvious that data compression methods can be used without the use of the data rate prediction and management techniques discussed in this patent.
In many cases, the data collected by the sensor network is used to control certain operations in the system to which the sensor network is attached. An example may be a system of pipelines and pumps delivering consumables and raw material to a chemical processing plant and transporting processed product. Several specific signals collected by the sensor network may be used by various control systems to maintain specific flow rates, pressures, temperatures, etc. Purposeful or accidental corruption of this data could have detrimental effects on the system. Illicit collection of system information could provide strategic advantages to competitors. Encryption of the data collected by the sensors can be employed to significantly hamper these sorts of inappropriate actions. Discussed next is the inclusion of data encryption techniques with the compression and data rate management methods previously disclosed. It is also obvious that encryption techniques can be used independent of the data rate prediction and management schemes and/or compression methods.
For the purposes of this patent disclosure, encryption methods can be characterized either as encrypting N bits with N bits or encrypting N bits with M bits (M>N). These two cases will be referred to as the 1:1 and the N:M cases. Systems employing N:M schemes are generally more secure than those implementing 1:1 schemes. As a result of the effective bandwidth gain realized with the compression approaches previously described, the more secure N:M methods can be employed at lower cost than without use of compression. Additionally, the increased bandwidth available as a result of compression and data rate management can also be employed for dynamic modification of encryption methods or keys providing yet more security to the transmitted data.
These disclosed data rate monitoring and allocation processes can be implemented either in a centralized top-down approach, in a de-centralized approach or in some combination. Since the specific details of the implementation of data rate management are substantially independent of the specifics of the relevant communications structure and do not directly impact the concepts taught in this patent disclosure, these methods of bandwidth management, compression and encryption are substantially independent of the specific communications or bus systems employed.
The objective of this previous discussion is to illustrate that these methods may be employed in arbitrary structures and are not limited to pipelines. The use of the pipeline example is for explanation purposes only and is not intended to limit application of these methods to any specific system or structure.
Processing elements contained in sensor elements 610 and central processing system 650 in
The previous discussion is not intended to limit the specific numbers, types and arrangements of sensors, the specific data rate management, data compression or data encryption techniques employed. References to specific techniques are used only as a means to explain an example of the art. Those skilled in these methods are aware of many alternate methods that can be employed.
In summary, systems, devices, and methods configured in accordance with exemplary embodiments relate to:
A physical structure augmented with several sensors or sensor nodes, coupled in some communications network in which the known dynamics of the physical structure and associated sensor array allows for the purposeful allocation of data rate among sensors and communications network in order to more effectively utilize available system bandwidth. In certain embodiments, the sensors may be one or more of an accelerometer, gyroscope, pressure, acoustic, temperature, magnetic, optical, torsion, tension or force measuring devices.
The sensor and physical structure as described above in which data rate communications and data processing and communications allocations are made based on the predictable propagation of the sensor detectable signals through the physical network.
The sensor and physical structure as described above in which data rate communications and data processing allocations are made as a result of detecting an event, tracking initial progress through the network and then predicting future propagation and the requirements of various sensors and communications systems as the event propagates through the system.
The sensor network attached to some physical structure as described above in which data compression techniques are used in conjunction with bandwidth allocation methods. These data compression methods may include combinations of lossy and lossless methods which are dynamically selected in order to efficiently communicate the event across the sensor array and communications network.
The sensor network attached to some physical structure as described above in which data compression techniques are used without bandwidth allocation methods. These data compression methods may include combinations of lossy and lossless methods which are dynamically selected in order to efficiently communicate the event across the sensor array and communications.
The sensor network attached to some physical structure as described above in which data encryption methods are employed in conjunction with data compression and data rate allocation methods. Use of these methods allows the use of stronger encryption schemes than would be possible without the use of both data rate allocation and compression control methods.
The sensor network attached to some physical structure as described above in which data encryption methods are employed with or without out data compression and with or without data rate allocation methods.
While at least one exemplary embodiment has been presented in the foregoing detailed description of the invention, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment of the invention, it being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope of the invention.
Provisional Utility Patent Application, Data Compression and Encryption in Sensor Networks, Application No. 61/593,907 Filing Date Feb. 2, 2012, Attorney Docket Number DH—15—006_P