Method for estimating velocities and/or displacements from accelerometer measurement samples

Abstract

There is provided a fall detector for use in detecting falls by a user, the fall detector comprising an accelerometer for producing a time series of measurement samples representing the acceleration acting on the fall detector; a processor for estimating a vertical velocity and / or vertical displacement of the fall detector from the measurement samples and using the estimated vertical velocity and / or vertical displacement to determine whether the user has suffered a fall; wherein the processor is configured to estimate a vertical velocity and / or vertical displacement of the fall detector from the measurement samples by estimating a corresponding time series of unit vectors representing acceleration due to gravity in the reference frame of the accelerometer from the time series of measurement samples; projecting each measurement sample onto the corresponding unit vector and subtracting acceleration due to gravity to give a series of estimates for the vertical acceleration of the fall detector; and integrating the series of estimates for the vertical acceleration over a time period to give a time series of values for the vertical velocity and / or vertical displacement of the fall detector.

Description

technical field [0001] The present invention relates to a method for estimating velocity and displacement from measurement samples from an accelerometer, and in particular to a method for estimating vertical velocity and vertical displacement that can be used when detecting a user fall. Background technique [0002] Every year, falls affect millions of people and result in significant injuries, especially among the elderly. In fact, it has been estimated that falls are one of the top three causes of death among older adults. A fall can be defined as a sudden, uncontrolled, and unintentional downward displacement of the body toward the ground, accompanied by a crash. [0003] A Personal Help Button (PHB) is available that requires the user to press a button to call for help in an emergency situation. However, if the user experiences a severe fall (for example, if they are knocked unconscious), the user may not be able to press the button, which will mean that help cannot be...

AI Technical Summary

Problems solved by technology

However, existing methods for estimating vertical velocity and vertical displacement are not able to provide sufficiently precise estimates when applied to measurement samples obtained from accelerometers of this type of fall detector

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