Patent ID: 7489249
Filing Date: 2009-02-10
Classification: G01S,G08B

Abstract:
1. An attitude detector for determining a horizontal resting orientation or a non-horizontal orientation of a monitoring device, the monitoring device is associated with a tracked person, the detector comprising: a first tip-over switch of a first operating angle; and a second tip-over switch of a second operating angle, said second operating angle is larger than said first operation operating angle, wherein said first and second tip-over switches are coupled to said monitoring device such that a change in orientation of the monitoring device causes an equivalent change in orientation of both said first and second tip-over switches and wherein each of said first and second tip-over switches gives an output signal of a first value when tilted by an angle above its respective operating angle and of a second value when tilted by an angle below its respective operating angle; a tip-over transition counter for counting transitions of said first tip-over switch during a predetermined time interval; and an attitude calculator module configured to receive readouts of said tip-over transition counter and said second tip-over switch, to calculate a tip-over counter value according to said readouts, and to determine the orientation of said monitoring device based on said tip-over counter value and a set of pre-loaded parameters.