Patent ID: 7031780

Claim:
A method for the determination of an unknown state variable (x) of a system ( 1 ) from a measured value (y) for implementation in an arithmetic unit ( 4 ) of a sensor system ( 2 ), said method comprising the steps of: obtaining a measured value (y) from a sensor system ( 2 ); establishing a cost function which indicates deviation of the measured value (y) from calibration functions as a function of the unknown state variable (x); establishing a relevant state region from the measured value (y); establishing approximation regions ( 30 ) and establishing for each approximation region at least one predetermined approximation function of the cost function in which a sum of the approximation function covers the entire relevant state region; determining all local minima ( 40 ) of said at least one approximation function of the cost function in each of said approximation regions such that each minimum is determined in a respective approximation region; and determining a global minimum ( 50 ) by comparing said local minima wherein said global minimum represents the state variable (x) of the system ( 1 ).