Abstract: The axes of an accelerometer, installed in a vehicle at an arbitrary orientation, may be realigned to the coordinate frame of the vehicle. In one implementation, a method may include determining, based on acceleration measurements from the accelerometer that likely corresponds to stopping, a dominant orientation of the accelerometer in relation to gravity, including calculating a first transformation angle and a second transformation angle as parameters to perform coordinate realignment of a coordinate frame of the accelerometer to a coordinate frame of the vehicle. The method may further include identifying, based on the acceleration measurements, an occurrence of acceleration events of the vehicle; determining, based on an analysis of the acceleration events, a third transformation angle; and storing the first, second, and third transformation angles.

Abstract: A wearable fall-detection device has a variety of sensors, including a pressure sensor, that provide signals for sampling environmental conditions acting on the device. An average of pressure data samples is used to determine a resultant that may indicate an amount of noise in a pressure data signal, and statistical analysis of the noise and the pressure signal average may be used to determine a confidence estimate value that indicates a level of confidence in the amount of noise that a pressure signal is subject to, or includes. The confidence estimate and known fall data, such as change in pressure between a person standing and lying, can create a threshold function that may adapt according to sampled data thus providing a customizable (either statically or dynamically) threshold function for comparing sensor data against rather than comparing data with just a linear threshold function.