Positioning system
AssigneeRoke Manor Research Limited
InventorNicholas Charles Lee
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Abstract
The invention provides a positional system intended to supplement positional information derived by means of a Global Positioning System (GPS), so as to provide positional data coverage in situations where the GPS data may be unreliable, for example due to local attenuation of satellite signals, in order to permit members of a group traversing difficult terrain to retain reasonably accurate information as to the whereabouts of the other group members should the GPS system fail. The positional system of the invention provides each group member with a readily transportable and relatively inexpensive inertial navigation system to generate approximate positional data and utilises radio location techniques to improve the accuracy of the approximate positional data.
Claims27
A positioning system for indicating to each member of a group information indicative of the respective locations of other members of the group, wherein each said member is provided with readily transportable inertial navigation equipment in order to provide positional information, active means to generate additional positional data, and means utilising said additional data to compensate, at least in part, for inaccuracies in the positional information provided by the inertial navigation equipment.
An arrangement wherein members of a group of people are provided with individual GPS equipments and a system according to any preceding claim is used to provide information as to the whereabouts of the group members during periods when GPS is inoperative.
13 An arrangement according to any of claims 10 to 12 wherein the system according to ally of claims 1 to 9 is activated periodically, even when the GPS system is functioning, in order to provide for a self-check and to monitor its performance against the GPS.
An arrangement according to claim 13 wherein, where inadequate performance is detected, an audible and/or visual waning is provided to alert the user to the fact that the back-up system is under--performing, and that the system should be checked.
A method for a group of mobile objects to determine the absolute position of each member of the group, the method comprising:
- using all inertial navigation system to generate data indicative of the absolute positions of the objects;
- receiving signals transmitted between the mobile objects and processing the signals to generate data indicative of the relative positions of the objects;
- processing the relative position data to generate corrective data;
- and
- correcting the absolute position data in accordance with the corrective data.
17 A method according to claim 16, the method comprising;
- determining the distances of the relative positions of the objects from the geometric mean;
- and
- correcting the absolute position data in dependence upon the determined distances;
A method according to any of claims 15 to 18 wherein
- time of flight measurements of the signals transmitted between the mobile objects are used to generate the relative position data.
An apparatus for use by a group of mobile objects to determine the position of each member of the group, the apparatus comprising:
- an inertial navigation system for generating data indicative of the absolute positions of the objects;
- equipment for receiving signals transmitted between the mobile objects and processing the signals to generate data indicative of the relative positions of the objects;
- and
- processing means for processing the relative position data to generate corrective data and correcting the absolute position data in accordance with the corrective data.
A system for a group of mobile objects to determine the absolute position of one or more members of the group, the system comprising:
- means for generating data that coarsely indicates the absolute positions of the objects of the group;
- measuring means for measuring the relative positions of the objects of the group;
- and
- processing means for refining the absolute position data in dependence upon the measured relative positions of the objects of the group to generate refined absolute position data indicating more accurately the absolute positions of one or more members of the group.
Dependencies are inferred from the claim text.