An angular velocity sensor for a rotor ( 2 ) and method of determining angular velocity in which the position at which event generation means ( 4 ) pass sensing means ( 5 ) is determined using information from the times at which the event generation means ( 4 ) passed the sensing means ( 5 ) during at least one previous complete revolution to of the rotor ( 2 ). Especially applicable to use of Hall Effect Sensors to detect commutation points of a brushless permanent magnet rotor in an Electric Power Assisted Steering apparatus.
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