Patent ID: 8743052

Claim:
A method comprising: receiving a first set of acceleration measurements from a first accelerometer that is structurally attached to a thumb of a user; receiving a second set of acceleration measurements from a second accelerometer that is structurally attached to a wrist of the user; detecting, based at least in part on the first set of acceleration measurements, when the thumb is tapped on a surface; when a tap of the thumb is detected, determining, based at least in part on the first set of acceleration measurements and the second set of acceleration measurements, an orientation of the first accelerometer relative to the second accelerometer; identifying, based on the orientation, a tap target, from among a plurality of tap targets located on fingers of the user, that was touched during the tap; assigning a symbol associated with the tap target to the tap; transmitting, storing, or displaying the symbol; receiving a first set of magnetic flux measurements from a first magnetometer that is structurally attached to the thumb of the user; and receiving a second set of magnetic flux measurements from a second magnetometer that is structurally attached to the wrist of the user; and wherein the orientation is determined based at least in part on the first set of magnetic flux measurements and the second set of magnetic flux measurements, and wherein determining the orientation comprises: filtering the first set acceleration measurements to determine a first estimate of acceleration experienced by the first accelerometer while the thumb was at rest with respect to a hand of the user on the tap target; filtering the second set of acceleration measurements to determine a second estimate of acceleration experienced by the second accelerometer while the thumb was at rest with respect to the hand of the user on the tap target; filtering the first set magnetic flux measurements to determine a first estimate of magnetic flux experienced by the first magnetometer while the thumb was at rest with respect to the hand of the user on the tap target; filtering the second set of magnetic flux measurements to determine a second estimate of magnetic flux experienced by the second accelerometer while the thumb was at rest with respect to the hand of the user on the tap target; and determining a rotation that will approximately align the first estimate of acceleration with the second estimate of acceleration and that also will approximately align the first estimate of magnetic flux with the second estimate of magnetic flux.