Method and system for recognizing behavior of object

A method comprising the steps of:

• measuring distances in a plurality of straight lines radially extending from a range finder to an object within a target area;
• extracting distances in two straight lines extending to opposite edges of the object from the measured distances to calculate a size of the object based on the extracted distances and an angle between the two straight lines;
• calculating data indicative of a state of the object based on the measured distances;
• storing object data indicative of the calculated data and the size in a memory;
• repeating the above steps a plurality of times;
• comparing n-th object data with (n-1)-th object data;
• determining that both the n-th object data and the (n-1)-th object data are data obtained from the same object when a difference between the sizes included in both the n-th object data and the (n-1)-th object data is smaller than a predetermined value;
• and
• recognizing a behavior of the object based on a difference between both the n-th object data and the (n-1)-th object data obtained from the same object.

A system comprising:

• a range finder for measuring distances in a plurality of straight lines radially extending from the range finder to an object within a target area to output distance data corresponding to the measured distances;
• means for periodically sampling the output distance data;
• means for calculating a gradient of the object with respect to one of the straight lines based on the sampled distance data;
• a memory for storing object data indicative of the calculated gradient;
• means for comparing n-th object data with (n-1)-th object data to calculate a rotation angle of the object;
• and
• means for recognizing a behavior of the object when the calculated rotation angle is larger than a predetermined value.

A system comprising:

• a range finder for measuring distances in a plurality of straight lines radially extending from the range finder to an object within a target area to output distance data corresponding to the measured distances;
• means for periodically sampling the output distance data;
• means for extracting distances in two straight lines extending to opposite edges of the object from the measured distances to calculate a size of the object based on the extracted distances and an angle between the two straight lines;
• means for calculating state data indicative of a state of the object based on the measured distances;
• a memory for storing object data indicative of the state data and the size;
• means for comparing n-th object data with (n-1)-th object data;
• means for determining that both the n-th object data and the (n-1)-th object data are obtained from the same object when a difference between the sizes included in both the object data is smaller than a predetermined value;
• means for outputting a judging signal representing a behavior of the object when a difference in the state data between the n-th object data and the (n-1)-th object data obtained from the same object exceeds a predetermined value.