Acoustic source localization system and applications of the same

Abstract

A system for locating an acoustic source from an acoustic event of the acoustic source. In one embodiment, the system includes a sensor network having a plurality of spatially separated sensor nodes each located in a predetermined position encountering acoustic waves generated by an acoustic event passing proximate to the plurality of spatially separated sensor nodes, where the plurality of spatially separated sensor nodes are synchronized to a common time base such that when the acoustic event is detected, information of the acoustic waves from each of the plurality of spatially separated sensor nodes is obtained and broadcasted through the sensor network. The system further includes a base station for receiving information of the acoustic waves broadcasted from the sensor network and processing the received information of the acoustic waves so as to locate the acoustic source of the acoustic event.

1 . A system for locating an acoustic source from an acoustic event of the acoustic source, comprising:
 a. a sensor network having a plurality of spatially separated sensor nodes, each spatially separated sensor node located in a predetermined position encountering acoustic waves generated by an acoustic event passing proximate to the plurality of spatially separated sensor nodes, wherein the plurality of spatially separated sensor nodes are synchronized to a common time base such that when the acoustic event is detected, information of the acoustic waves from each of the plurality of spatially separated sensor nodes is obtained and broadcasted through the sensor network, the information of the acoustic waves including the time of arrival of the acoustic waves at the corresponding sensor node; and   b. a base station for receiving the information of the acoustic waves broadcasted from the sensor network and processing the received information of the acoustic waves so as to locate the acoustic source of the acoustic event.   
   
   
       2 . The system of  claim 1 , further comprising a middleware service for synchronizing the plurality of spatially separated sensor nodes of the sensor network and routing message through the sensor network. 
   
   
       3 . The system of  claim 1 , wherein the plurality of spatially separated sensor nodes communicates each other wirelessly. 
   
   
       4 . The system of  claim 1 , wherein each of the plurality of spatially separated sensor nodes comprises a mote and an acoustic sensor board in communication with the mote. 
   
   
       5 . The system of  claim 4 , wherein the acoustic sensor board comprises at least one acoustic sensor. 
   
   
       6 . The system of  claim 1 , wherein the acoustic wave comprises a shock wave. 
   
   
       7 . The system of  claim 1 , wherein the base station comprises a computer. 
   
   
       8 - 19 . (canceled) 
   
   
       20 . A system for locating an acoustic source from an acoustic event of the acoustic source, comprising:
 a. a sensor network having a plurality of spatially separated sensor nodes, each spatially separated sensor node having a unique node ID and located in a predetermined position encountering acoustic waves generated by an acoustic event passing proximate to the plurality of spatially separated sensor nodes;   b. means for synchronizing the plurality of spatially separated sensor nodes of the sensor network to a common time base;   c. means for obtaining information of the acoustic waves from each of the plurality of spatially separated sensor nodes when the acoustic event is detected, the information of the acoustic waves including the time of arrival of the acoustic waves at the corresponding sensor node;   d. means for broadcasting the obtained information of the acoustic waves from each of the plurality of spatially separated sensor nodes through the sensor network; and   e. a base station for receiving information of the acoustic waves broadcasted from the sensor network and processing the received information of the acoustic waves so as to locate the acoustic source of the acoustic event.   
   
   
       21 . The system of  claim 20 , wherein the plurality of spatially separated sensor nodes communicates each other wirelessly. 
   
   
       22 . The system of  claim 20 , wherein each of the plurality of spatially separated sensor nodes comprises a mote and an acoustic sensor board in communication with the mote. 
   
   
       23 . The system of  claim 22 , wherein the acoustic sensor board comprises at least one acoustic sensor. 
   
   
       24 . The system of  claim 20 , wherein the synchronizing means comprises a flooding time synchronization protocol. 
   
   
       25 . The system of  claim 24 , wherein the flooding time synchronization protocol comprises the steps of:
 a. electing a node from the plurality of spatially separated sensor nodes as a root node at starting time of the sensor network to which the rest of the plurality of spatially separated sensor nodes will be synchronized;   b. periodically broadcasting a message by the root node to nodes within a broadcast radius of the root node, the message containing a root ID, a sequence number and a time stamp, the root ID being the unique node ID of the root node, the sequence number being a monotonically increased unique ID generated by the root node, the time stamp being the globe time known by the root node at the time of message transmission;   c. recording its own local time when receiving the broadcasted message so as to have a reference point with an estimate of the global time along with its own local time for each of the nodes within a broadcast radius of the root node if the sequence number for the broadcasted message is higher than the highest sequence number stored in a reference table in the corresponding node;   d. synchronizing each of the nodes by updating its reference table with the reference point, and the sequence number and current root ID;   e. re-broadcasting the message using its highest sequence number and current root ID by the synchronized node to nodes within a broadcast radius of the synchronized node so as to synchronize the nodes;   f. repeating steps (b)-(e) to synchronize the sensor network to the root node; and   g. re-electing a root node if a node does not received a message for a predetermined period of time.   
   
   
       26 . The system of  claim 20 , wherein the broadcasting means comprises a directed flood-routing framework engine. 
   
   
       27 . The system of  claim 26 , wherein the directed flood-routing framework engine performs the steps of:
 a. creating a flooding policy that defines a direction of flooding and a way of which intermediate neighboring nodes re-broadcast messages;   b. keeping recently received data packets in a table together with their priority that is managed by the flooding policy;   c. periodically selecting the data packets with the highest priority;   d. packing the selected data packets into a single radio message; and   e. broadcasting the packed data packets to the neighboring nodes.   
   
   
       28 . The system of  claim 20 , wherein the base station runs a sensor fusion algorithm. 
   
   
       29 . The system of  claim 28 , wherein the sensor fusion algorithm comprises the steps of:
 a. defining a consistency function from the obtained information of the acoustic waves and positions of the corresponding sensor nodes;   b. finding a maximum of the consistency function; and   c. identifying a location of the maximum of the consistency function as the location of the acoustic source of the acoustic event,   
     wherein the consistency function is configured such that the consistency function automatically classifies and eliminates erroneous measurements and multi-path effects.