Method for resolving presence, orientation and activity in a defined

Abstract

A method for resolving presence, orientation and activity of a person within a defined space utilizes at least two electrodes proximate to the space to be observed. A characterization of the position and orientation is obtained by providing a pattern of measurement clusters each associated with a position and an orientation. An AC signal is applied to one electrode, and the current measured from that electrode to any other electrodes included in the system, and which are effectively connected to the ground return of the AC-coupled electrode. A person (or object) to be sensed intercepts a part of the electric field extending between the AC-coupled 'sending' electrode and the other 'receiving' electrodes, the amount of the field intercepted depending on the size and orientation of the sensed person, whether or not the person provides a grounding path, and the geometry of the distributed electrodes. Given the nonlinear spatial dependence of the field, multiple electrodes can reliably distinguish among a set of expected cases. The invention can be configured to detect not only static positions and orientations, but also motion through a defined space. This is accomplished by taking sequential measurements at different times and utilizing the time variation in signal magnitudes as well as the absolute magnitudes themselves.