Patent ID: 7739034

Claim:
A method for landmark navigation of a vehicle, comprising: a. storing data in the vehicle representing locations of each of a plurality of optical beacons in a field of operation, wherein each optical beacon emits or reflects an optical signal at a predetermined blink frequency and with a 50% duty cycle and such that the plurality of optical beacons are not synchronized; b. during a position update cycle: i. capturing a pair of image frames in the field of operation with at least one imaging device on the vehicle, wherein capturing comprises capturing the pair of image frames such that a time interval separating the capture of the image frames in the pair is equal to one-half of a blink period corresponding to the predetermined blink frequency of the optical beacons, and the time of capture for each image in the pair of image frames coincides with emission or reflection by a different set of optical beacons; ii. generating data representing a difference frame between the two image frames in the pair of image frames; iii. identifying pixel locations of optical beacons in the difference frame; and iv. deriving a position and orientation of the vehicle from data representing pixel locations of optical beacons in the difference frame and from the stored data representing the location of each of the optical beacons in the field of operation.