Based on the research of data acquisition prineiple

and characteristics wave vector extraction method of the anisotropic magnetoresistive（AMR） sensor

a new vehicle detection algorithm based on AMR sensor

called the vehicle detection algorithm of adaptive state machine is presented.The algorithm can adaptively updates the threshold and the baseline

uses the state machine to achieve the aim of the accurate and efficient vehicle detection.It can be used for the detection of road traffic flow

and can be used in vehicle guidance system in large parking lot.