Patent ID: 8368388

Claim:
A method for increasing intrinsic safety of an arrangement for detecting movements of a body, the arrangement comprising a magnetic encoder ( 5 , 25 ) and a sensor ( 26 ), wherein the sensor ( 26 ) has at least two sensor elements (S 1 , S 2 ) which are magnetically coupled to the magnetic encoder ( 5 , 25 ), the method comprising: comparing output signals from at least two separate signal paths (S 1 , f 1 ; S 2 , f 2 ), wherein the at least two separate signal paths (S 1 ,f 1 ;S 2 ,f 2 ) includes at least one primary measuring signal path (S 1 ,f 1 ) and at least one observing signal path (S 2 ,f 2 ), each of the two separate signal paths (S 1 ,f 1 ;S 2 ,f 2 ) corresponds to at least one of the sensor elements (S 1 , S 2 ), wherein the at least one primary measuring signal path (S 1 , f 1 ) is constructed such that a temporal profile of the output signal from the at least one primary measuring signal path (S 1 ,f 1 ) during normal operation has patterns essentially corresponding to a relative speed between the sensor and a pole pair of the magnetic encoder that are detected by said sensor that represent a wheel rotational speed, and the at least one observing signal path (S 2 , f 2 ) is constructed such that a temporal profile of the output signal from the at least one observing signal path (S 2 ,f 2 ) includes patterns, an occurrence of said patterns of the at least one observing signal path essentially corresponding to double the relative speed between the sensor and the pole pair of the magnetic encoder detected by said sensor that represent double the wheel rotational speed, wherein the comparing output signals includes comparing output signals from the at least one primary measuring signal path (S 1 , f 1 ) and the at least one observing signal path (S 2 , f 2 ) with one another in a comparator ( 30 ), with the comparator ( 30 ) being designed such that, responsive to the output signals from the at least one primary measuring signal path and from the at least one observing signal path essentially matching, a comparison result is produced indicative of an erroneous function of the at least one primary measuring signal path (S 1 , f 1 ); and transmitting the comparison result to an electronic control unit (ECU).