Patent ID: 7236880

Claim:
A method for determining at least two spatial degrees of freedom of a creature ( 3 ) relative to an environment, comprising the steps of: connecting a creature to a locating member ( 4 ) including a transducer ( 5 ), operating said transducer to determine at least two spatial degrees of freedom of the transducer relative to the environment by i) the transducer receiving incident optical signals from at least two signal sources ( 9 ) located in the environment and recording the relative incident positions of the received signals on a surface of the transducer, ii) based on the recorded relative positions of the received signals, calculating directions (φ 1 , θ 1 ; φ 2 , θ 2 ; φ 3 , θ 3 ;) of sight lines extending between respective signal source and the transducer, with respect to at least two of said at least two signal sources, and iii) calculating said at least two spatial degrees of freedom of the transducer relative to the environment by using the directions of the sight lines, the method further comprising: determining said at least two spatial degrees of freedom of the creature from said at least two spatial degrees of freedom of the transducer, the creature and the locating member being mechanically connected relative to each other within a known limited spatial interval with respect to said at least two spatial degrees of freedom.