System and method for ultrasound distance detection

Abstract

A method of ultrasound distance detection includes identifying an ultrasound echo from an object and determining a distance between a mobile platform and the object based upon the ultrasound echo. Identifying the ultrasound echo includes dividing a sonic waveform received by the mobile platform into packets, filtering the packets using at least a threshold packet bandwidth to identify one or more candidate packets that are not noise, and identifying the ultrasound echo from the one or more candidate packets. The threshold packet bandwidth is multiple of an average width of previously known echoes.

What is claimed is: 
     
         1 . A method of ultrasound distance detection comprising:
 identifying an ultrasound echo from an object by:
 dividing a sonic waveform received by a mobile platform into packets; 
 filtering the packets using at least a threshold packet bandwidth to identify one or more candidate packets that are not noise, the threshold packet bandwidth being multiple of an average width of previously known echoes; and 
 identifying the ultrasound echo from the one or more candidate packets; and 
   determining a distance between the mobile platform and the object based upon the ultrasound echo.   
     
     
         2 . The method of  claim 1 , wherein filtering the packets comprises filtering the packets using the threshold packet bandwidth and a threshold packet amplitude to identify the one or more candidate packets, the threshold packet amplitude being a fraction of an average amplitude of the previously known echoes. 
     
     
         3 . The method of  claim 1 , wherein dividing the sonic waveform into the packets comprises dividing the sonic waveform into time intervals, the time intervals corresponding to the packets. 
     
     
         4 . The method of  claim 3 , wherein each of the time intervals has a duration based upon a frequency of the sonic waveform. 
     
     
         5 . The method of  claim 3 , wherein at least two of the time intervals have different durations. 
     
     
         6 . The method of  claim 3 , wherein the time intervals have a same duration. 
     
     
         7 . The method of  claim 1 , wherein dividing the sonic waveform into the packets comprises using a peak selection technique to select the packets based on peaks in the sonic waveform. 
     
     
         8 . The method of  claim 1 , wherein filtering the packets further comprises discarding one of the packets that has an area less than a predetermined threshold value as noise. 
     
     
         9 . The method of  claim 1 , further comprising, before identifying the ultrasound echo:
 determining an aftershock waveform; and   subtracting the aftershock waveform from the sonic waveform.   
     
     
         10 . The method of  claim 9 , wherein determining the aftershock waveform comprises receiving an ultrasound waveform under reduced echo and/or reduced noise conditions and determining the aftershock waveform based on the received ultrasound waveform. 
     
     
         11 . The method of  claim 9 , wherein:
 determining the aftershock waveform comprises determining a timing of the aftershock waveform relative to a corresponding ultrasound emission, and   subtracting the aftershock waveform comprises subtracting the aftershock waveform according to the timing.   
     
     
         12 . The method of  claim 1 , wherein identifying the ultrasound echo from the one or more candidate packets comprises identifying the ultrasound echo by motion estimation of the mobile platform. 
     
     
         13 . The method of  claim 12 , wherein the motion estimation comprises predicting a location of the mobile platform according to a dynamic model. 
     
     
         14 . The method of  claim 13 , wherein the dynamic model is a linear dynamic model. 
     
     
         15 . The method of  claim 13 , wherein the dynamic model is a non-linear dynamic model. 
     
     
         16 . The method of  claim 13 , wherein the dynamic model is a fixed-speed dynamic model, a planar dynamic model, or a non-planar dynamic model. 
     
     
         17 . The method of  claim 13 , wherein the motion estimation further comprises identifying the ultrasound echo according to the predicted location of the mobile platform. 
     
     
         18 . The method of  claim 17 , wherein identifying the ultrasound echo according to the predicted location of the mobile platform comprises:
 estimating, based on the dynamic model and using a state of the mobile platform at a time when an ultrasound wave is emitted from the mobile platform, a state of the mobile platform at a time when the ultrasound echo is expected to be received by the mobile platform;   predicting the location of the mobile platform at the time when the ultrasound echo is expected to be received by the mobile platform based on an average value and a variance of the state of the mobile platform at the time when the ultrasound echo of the ultrasound wave is expected to be received by the mobile platform;   determining a set of timing constraints on a timing of the ultrasound echo being received by the mobile platform using the predicted location of the mobile platform; and   identifying the ultrasound echo from at least one of the one or more candidate packets that is within the set of timing constraints.   
     
     
         19 . A mobile platform comprising:
 an ultrasound receiver configured to receive an ultrasound echo from an object; and   a processor configured to:
 identify the ultrasound echo by:
 dividing a sonic waveform received by the ultrasound receiver into packets; 
 filtering the packets using at least a threshold packet bandwidth to identify one or more candidate packets that are not noise, the threshold packet bandwidth being multiple of an average width of previously known echoes; and 
 identifying the ultrasound echo from the one or more candidate packets; and 
 
 determine a distance between the mobile platform and the object based upon the ultrasound echo. 
   
     
     
         20 . A non-transitory computer-readable medium storing instructions that, when executed by a processor, cause the processor to:
 identify an ultrasound echo from an object by:
 dividing a sonic waveform received by a mobile platform into packets; 
 filtering the packets using at least a threshold packet bandwidth to identify one or more candidate packets that are not noise, the threshold packet bandwidth being multiple of an average width of previously known echoes; and 
 identifying the ultrasound echo from the one or more candidate packets; and 
   determine a distance between the mobile platform and the object based upon the ultrasound echo.