Patent ID: 7415380
Filing Date: 2008-08-19
Classification: G01P,G11B

Abstract:
1. A fall detection device comprising: a three-axial acceleration sensor for detecting acceleration components in three axes crossing perpendicularly with each other, and for outputting acceleration component signals; a first storage unit for storing a rotating fall determining value to determine a rotating fall upon falling, a determining time interval with which the acceleration component signal is obtained again to determine the rotating fall, and an angular difference determining value upon determining the rotating fall; a first obtaining unit for obtaining a first acceleration component signal in each of the three axes from the three-axial acceleration sensor; a first calculating unit for combining the first acceleration component signal in each of the three axes to calculate a first composite vector value; a first reading unit for reading the rotating fall determining value from the first storage unit; a first comparing unit for comparing the rotating fall determining value with the first composite vector value; a second reading unit for reading the determining time interval from the first storage unit when the first composite vector value is grater than the rotating fall determining value; a second obtaining unit for obtaining a second acceleration component signal in each of the three axes from the three-axial acceleration sensor after the determining time interval; a second calculating unit for combining the second acceleration component signal in each of the three axes to calculate a second composite vector value; a second comparing unit for comparing the rotating fall determining value with the second composite vector value; a third calculating unit for calculating an angular difference between a first angle of each of testing surfaces calculated from the first acceleration component signal in each of the three axes and a second angle of each of the testing surfaces calculated from the second acceleration component signal in each of the three axes when the second composite vector value is greater than the rotating fall determining value; a third reading unit for reading the angular difference determining value from the first storage unit; a third comparing unit for comparing the angular difference determining value with the angular difference of each of the testing surfaces; a first determining unit for determining the rotating fall when at least one of the angular differences of the testing surfaces is greater than the angular difference determining value; a second storage unit for storing a free fall determining value to determine a free fall upon falling; a fourth reading unit for reading the free fall determining value from the second storage unit; a fourth comparing unit for comparing the free fall determining value with the first composite vector value; a fifth reading unit for reading the determining time interval from the first storage unit when the first composite vector value is smaller than the free fall determining value; a third obtaining unit for obtaining a third acceleration component signal in each of the three axes from the three-axial acceleration sensor after the determining time interval; a fourth calculating unit for combining the third acceleration component signal in each of the three axes to calculate a third composite vector value; a fifth comparing unit for comparing the free fall determining value with the third composite vector value; and a second determining unit for determining the free fall when the third composite vector value is smaller than the free fall determining value.