Digital ultrasonic emitting base station

Abstract

An acoustic tracking system is provided that includes receivers that detect first acoustic signals from a first set of transmitters disposed on a digital pen and second acoustic signals from a second set of transmitters disposed on a base station. The acoustic tracking system also includes a processing component that defines a two-dimensional plane on which the base station lies and determines a three-dimensional position of the digital pen relative to the base station. The processing component projects the three-dimensional position of the digital pen onto the two-dimensional plane and records, based on the projected three-dimensional position, the three-dimensional position of the digital pen relative to the base station, where the recorded three-dimensional position of the digital pen represents an object representative of movement of the digital pen.

What is claimed is: 
     
         1 . An acoustic tracking system, comprising:
 a first plurality of receivers that detects first acoustic signals from a first set of transmitters disposed on a digital pen;   a second plurality of receivers that detects second acoustic signals from a second set of transmitters disposed on a base station, wherein the base station is coupled to a motion detector that detects movement of the base station, and in response to the movement, the base station activates the second set of transmitters to emit the second acoustic signals;   a processing component that defines, based on the second acoustic signals, a two-dimensional plane on which the base station lies, determines, based on the first and second acoustic signals, a three-dimensional position of the digital pen relative to the base station, and projects the three-dimensional position of the digital pen onto the two-dimensional plane; and   an application controller that records, based on the projected three-dimensional position of the digital pen onto the two-dimensional plane, the three-dimensional position of the digital pen relative to the base station, wherein the recorded three-dimensional position of the digital pen represents an object representative of movement of the digital pen.   
     
     
         2 . The acoustic tracking system of  claim 1 , wherein the first plurality of receivers includes one or more microphones. 
     
     
         3 . The acoustic tracking system of  claim 1 , wherein the processing component determines a first point corresponding to a bottom left corner of the base station, determines a second point corresponding to a bottom right corner of the base station, and determines a third point corresponding to a top corner of the base station, and wherein an equation of the two-dimensional plane passes through the first, second, and third points. 
     
     
         4 . The acoustic tracking system of  claim 1 , wherein the base station is attached to a notepad. 
     
     
         5 . The acoustic tracking system of  claim 4 , wherein the processing component defines a boundary that corresponds to the notepad and lies on the two-dimensional plane. 
     
     
         6 . The acoustic tracking system of  claim 5 , wherein the processing component determines a position of one or more transmitters of the second set of transmitters disposed on the base station. 
     
     
         7 . The acoustic tracking system of  claim 6 , wherein the processing component translates the positions of the second set of transmitters into the defined boundary. 
     
     
         8 . The acoustic tracking system of  claim 5 , wherein the defined boundary corresponds to a position of the notepad. 
     
     
         9 . The acoustic tracking system of  claim 5 , wherein the defined boundary corresponds to a length of the notepad. 
     
     
         10 . The acoustic tracking system of  claim 9 , wherein the defined boundary corresponds to a width of the notepad. 
     
     
         11 . The acoustic tracking system of  claim 1 , wherein the processing component determines that the three-dimensional position of the digital pen is within the defined boundary. 
     
     
         12 . The acoustic tracking system of  claim 11 , wherein in response to a determination that the three-dimensional position of the digital pen is within the defined boundary, the processing component transforms the three-dimensional position of the digital pen into a two-dimensional coordinate system relative to the base station and a spatial orientation of the base station. 
     
     
         13 . The acoustic tracking system of  claim 1 , wherein the three-dimensional position of the digital pen corresponds to a three-dimensional position of a tip of the digital pen. 
     
     
         14 . A method of recording an object based on movement of a digital pen relative to a base station, comprising:
 detecting, by a first plurality of receivers coupled to a computing device, first acoustic signals from a first set of transmitters disposed on a digital pen;   detecting, by a second plurality of receivers coupled to the computing device, second acoustic signals from a second set of transmitters disposed on a base station attached to a notepad;   defining, based on the second acoustic signals, a two-dimensional plane on which the base station lies;   defining a boundary that corresponds to the notepad and that lies on the two-dimensional plane;   determining, based on the first and second acoustic signals, a three-dimensional position of the digital pen relative to the base station,   in response to a determination that the three-dimensional position of the digital pen is within the defined boundary, transforming the three-dimensional position of the digital pen into a two-dimensional coordinate system relative to the base station and a spatial orientation of the base station; and   recording the three-dimensional position of the digital pen relative to the base station, wherein the recorded three-dimensional position of the digital pen represents an object representative of movement of the digital pen.   
     
     
         15 . The method of  claim 14 , comprising:
 projecting the three-dimensional position of the digital pen onto the two-dimensional plane, wherein the recording includes recording, based on the projected three-dimensional position of the digital pen onto the two-dimensional plane, the three-dimensional position of the digital pen relative to the base station.   
     
     
         16 . The method of  claim 14 , comprising:
 determining a first point corresponding to a bottom left corner of the base station;   determining a second point corresponding to a bottom right corner of the base station; and   determining a third point corresponding to a top corner of the base station, wherein an equation of the two-dimensional plane passes through the first, second, and third points.   
     
     
         17 . The method of  claim 14 , comprising:
 determining a position of one or more transmitters of the second set of transmitters disposed on the base station; and   translating the positions of the second set of transmitters into the defined boundary.   
     
     
         18 . The method of  claim 14 , wherein the defined boundary corresponds to a position of the notepad. 
     
     
         19 . The method of  claim 14 , wherein the defined boundary corresponds to a length and a width of the notepad. 
     
     
         20 . The method of  14 , wherein the three-dimensional position of the digital pen corresponds to a three-dimensional position of a tip of the digital pen.