Force sensor baseline calibration

Abstract

Systems, methods, and apparatus for force sensor baseline calibration are disclosed herein. 1. Apparatus may include a force sensor configured to receive a plurality of force signals from a plurality of force sensitive elements, where the plurality of force signals is associated with a first touch at a first location of a sensing surface. The apparatus may include a touch sensor configured to receive a touch signal associated with the first touch. The apparatus may include processing logic coupled to the force sensor and the touch sensor, the processing logic being configured to determine a magnitude of a first component force associated with the first touch based, at least in part, on the plurality of force signals and the touch signal. The first component force may characterize a force applied by the first touch at the first location of the sensing surface.

What is claimed is: 
     
         1 . An apparatus comprising:
 a force sensor configured to receive a plurality of force signals from a plurality of force sensitive elements, wherein the plurality of force signals is associated with a first touch at a first location of a sensing surface;   a touch sensor configured to receive a touch signal associated with the first touch; and   processing logic coupled to the force sensor and the touch sensor, the processing logic being configured to determine a magnitude of a first component force associated with the first touch based, at least in part, on the plurality of force signals and the touch signal, the first component force characterizing a force applied by the first touch at the first location of the sensing surface.   
     
     
         2 . The apparatus of  claim 1 , wherein the plurality of force signals is further associated with a second touch at a second location of the sensing surface, wherein the first touch and the second touch are concurrent, and wherein the processing logic is further configured to determine a magnitude of a second component force associated with the second touch. 
     
     
         3 . The apparatus of  claim 2 , wherein the processing logic is further configured to determine a total force associated with the first touch and the second touch, and wherein the processing logic is further configured to determine a centroid location associated with the first touch and the second touch. 
     
     
         4 . The apparatus of  claim 3 , wherein the first component force and the second component force are determined based, at least in part, on a lever balance equation. 
     
     
         5 . The apparatus of  claim 4 , wherein the lever balance equation is:
     FS 1 *L 1 =FS 2 *L 2,   and   wherein FS 1  characterizes the first component force, L 1  characterizes a distance between the first location and the centroid location, FS 2  characterizes the second component force, and L 2  characterizes a distance between the second location and the centroid location.   
     
     
         6 . The apparatus of  claim 3 , wherein the plurality of force signals is further associated with a third touch at a third location of the sensing surface, wherein the first touch, the second touch, and the third touch are concurrent, and wherein the processing logic is further configured to determine a magnitude of a third component force associated with the third touch. 
     
     
         7 . The apparatus of  claim 6 , wherein the processing logic is configured to determine a first magnitude of the first component force, a second magnitude of the second component force, and a third magnitude of the third component force based on a system of equations. 
     
     
         8 . The apparatus of  claim 7 , wherein the system of equations includes a plurality of equations comprising:
     FS 1*( x−x   1 )+ FS 2*( x−x   2 )+ FS 3*( x−x   3 )=0;       FS 1*( y−y   1 )+ FS 2*( y−y   2 )+ FS 3*( y−y   3 )=0;       FS 1+ FS 2+ FS 3= sA+sB+sC+sD;      and   wherein FS 1  characterizes the first component force, wherein FS 2  characterizes the second component force, wherein FS 3  characterizes the third component, wherein (x 1 , y 1 ) characterizes a first Cartesian coordinate location of the first touch determined based on the touch signal, wherein (x 2 , y 2 ) characterizes a second Cartesian coordinate location of the second touch determined based on the touch signal, wherein (x 3 , y 3 ) characterizes a third Cartesian coordinate location of the third touch determined based on the touch signal, and wherein sA, sB, sC, and sD represent the plurality of force signals received from the plurality of force sensitive elements.   
     
     
         9 . The apparatus of  claim 1 , wherein the plurality of force sensitive elements includes at least three force sensitive elements. 
     
     
         10 . The apparatus of claim , wherein the processing logic is further configured to update a baseline associated with the plurality of force signals. 
     
     
         11 . A method comprising:
 receiving a plurality of force signals from a plurality of force sensitive elements, wherein the plurality of force signals is associated with a first touch at a first location of a sensing surface;   receiving a touch signal associated with the first touch; and   determining a first magnitude of a first component force associated with the first touch based, at least in part, on the plurality of force signals and the touch signal, the first component force characterizing a force applied by the first touch at the first location of the sensing surface.   
     
     
         12 . The method of  claim 11 , wherein the plurality of force signals is further associated with a second touch at a second location of the sensing surface and a third touch at a third location of the sensing surface, and wherein the first touch, the second touch, and the third touch are concurrent. 
     
     
         13 . The method of  claim 12  further comprising:
 determining a total force associated with the first touch, the second touch, and the third touch; and 
 determining a centroid location associated with the total force. 
 
     
     
         14 . The method of  claim 13  further comprising:
 determining a second magnitude of a second component force associated with the second touch; and 
 determining a third magnitude of a third component force associated with the third touch. 
 
     
     
         15 . The method of  claim 11  further comprising:
 updating a baseline associated with the plurality of force signals. 
 
     
     
         16 . A system comprising:
 a sensing surface;   a plurality of force sensitive elements configured to measure forces associated with the sensing surface, and further configured to generate a plurality of force signals based on the measured forces;   a force sensor configured to receive the plurality of force signals from the plurality of force sensitive elements, wherein the plurality of force signals is associated with a first touch at a first location of the sensing surface;   a touch sensor configured to receive a touch signal associated with the first touch; and   processing logic coupled to the force sensor and the touch sensor, the processing logic being configured to determine a first magnitude of a first component force associated with the first touch based, at least in part, on the plurality of force signals and the touch signal, the first component force characterizing a force applied by the first touch at the first location of the sensing surface.   
     
     
         17 . The system of  claim 16 , wherein the plurality of force signals is further associated with a second touch at a second location of the sensing surface, wherein the first touch and the second touch are concurrent, and wherein the processing logic is further configured to determine a magnitude of a second component force associated with the second touch. 
     
     
         18 . The system of  claim 17 , wherein the processing logic is further configured to determine a total force associated with the first touch and the second touch, and wherein the processing logic is further configured to determine a centroid location associated with the first touch and the second touch. 
     
     
         19 . The system of  claim 18 , wherein the processing logic is configured to determine the first magnitude of the first component force and a second magnitude of the second component force are determined based, at least in part, on a lever balance equation. 
     
     
         20 . The system of  claim 18 , wherein the processing logic is configured to determine the first magnitude of the first component force and a second magnitude of the second component force based on a system of equations.