Systems and Methods for Calibrating an Accelerometer

A method for calibrating an accelerometer to reduce an error of the accelerometer, comprising:

• receiving accelerometer datasets from the accelerometer at a plurality of times;
• receiving magnetometer datasets from the magnetometer at the plurality of times;
• adding the received accelerometer datasets and the received magnetometer datasets at the plurality of times to a data store when a difference between the received magnetometer datasets and a magnetometer dataset last stored in, a data store is greater than a defined threshold;
• aggregating the received accelerometer datasets and the magnetometer datasets with an accelerometer dataset and the magnetometer dataset last stored in the data store when the difference between the received magnetometer dataset and the magnetometer dataset last stored in the data store is less than a defined threshold;
• estimating a gravity vector for each accelerometer dataset stored in the data store;
• estimating a magnetic field vector for each magnetometer dataset stored in the data store;
• calculating a characteristic that is a function of an angle between the respective estimated gravity vector and the respective estimated magnetic field vector;
• calculating a figure of merit over the plurality of times that is a function of the characteristic;
• and
• dynamically adjusting a calibration parameter of the accelerometer such that the figure of merit converges to a value,
• wherein adjusting the calibration parameter reduces the error of the accelerometer.

A system comprising:

• an accelerometer;
• a magnetometer;
• a processor;
• and
• a memory storing a calibration parameter of the accelerometer and instructions to be executed by the processor, the instructions comprising:
• estimating a gravity vector using the accelerometer at a plurality of times;
• estimating a magnetic field vector using a magnetometer at the plurality of times;
• calculating a characteristic that is a function of an angle between the estimated gravity vector and the estimated magnetic field at each of the plurality of times;
• calculating a figure of merit over the plurality of times that is a function of the characteristic;
• and
• dynamically adjusting a calibration parameter of the accelerometer during ordinary use of the electronic device such that the figure of merit converges to a value,
• wherein adjusting the calibration parameter reduces an error of the accelerometer.