Abstract: A method and system for detecting that an object, person or vehicle has deviated in space or time from its prescribed route, and guiding it back to the prescribed route, according to strictness criteria predefined by a controlling authority or authorities. The invention allows controlling authorities to pre-specify a level of strictness suiting the object, person or vehicle and purpose of travel, by which the object, person or vehicle is guided back to the prescribed route autonomously, enabling return to route according to established policies, without the necessity of further communication with controlling authorities. The method and system thus operate semi-autonomously, with strictness parameters predefined by the central authorities, and the object, person or vehicle operating with some degree of latitude within those strictness parameters.

Abstract: A client/server navigation system utilizes partial route guidance trees, enabling a thin, mobile client to detect route deviation and provide alternate instructions while awaiting response from a server. The system (10) consists of a server (28) containing a network database and route-calculation program; a client (26) capable of obtaining (12) its current location and destination, displaying route instructions (22), and determining when it needs additional instructions from the server (20,24); and communication (30,32,34,36) between the client (26) and server (28). The invention allows for long routes and responsive operation on a small, low-powered client despite lags and lapses in communication.