Patent ID: 7797125

Claim:
A method for determining a roll angle for triggering an occupant protection device comprising: detecting, by a processor, a transverse acceleration (a y ) and a vertical acceleration (a z ) of the vehicle; and estimating, by the processor, the roll angle (α) of the vehicle based on the detected transverse acceleration (a y ) and the detected vertical acceleration (a z ); wherein the estimating includes comparing the detected transverse acceleration (a y ) to a first threshold value and comparing the detected vertical acceleration (a z ) to a second threshold value, the roll angle (α) being estimated using a first approximation when the transverse acceleration (a y ) is greater than the first threshold value and the vertical acceleration (a z ) is greater than the second threshold value, and the roll angle (α) being estimated using a second approximation when at least one of the transverse acceleration (a y ) is less than or equal to the first threshold value and the vertical acceleration (a z ) is less than or equal to the second threshold value, and wherein trigonometric functions for estimating the roll angle ({acute over (α)}) are approximated by corresponding Taylor series expansions, a sine function of the roll angle ({acute over (α)}) being approximated according to sin {acute over (α)}≈{acute over (α)}+o(á 2 ) for the first and second approximations, a cosine function of the roll angle ({acute over (α)}) being approximated according to cos {acute over (α)}≈1−{acute over (α)} 2 /2+o({acute over (α)} 4 ) for the first approximation and being approximated according to cos {acute over (α)}≈1+o({acute over (α)} 2 ) for the second approximation.