WO2002013417A1

WO2002013417A1 - Relative location determination system

Info

Publication number: WO2002013417A1
Application number: PCT/US2001/022929
Authority: WO
Inventors: William E. Clise; R. Michael Crowson
Original assignee: Locate Networks, Inc.
Priority date: 2000-08-04
Filing date: 2001-07-19
Publication date: 2002-02-14
Also published as: AU2001280666A1

Abstract

A location determination service (30) receives location information from one or more loction detection devices including GPS receivers. The location determination service (30) calculates the relative position between the one or more location detection devices (14, 16) and returns the relative position information back to the requestor. Alternatively, the location determination service (30) may calculate the relative position between a single location detection device and a known reference point.

Description

RELATIVE LOCATION DETERMINATION SYSTEM

Field of the Invention The present invention relates to location detection systems in general, and in particular to GPS based location detection systems. Background of the Invention

In a global positioning satellite (GPS) system, a receiver receives highly accurate timing signals transmitted from three or more overhead satellites. Based on the relative time at which signals are received from each of the satellites, the receiver can compute its location with a high degree of precision. While the GPS system has revolutionized the ability of people to determine their own location, no current GPS system exists that allows a person to determine their relative location with respect to another object or person. For example, rescue personnel cannot currently use a GPS system to accurately inform them how far they are away from a person needing aid. Therefore, there is a need for a system that allows a user to determine the relative location between two GPS receivers or the relative location between a GPS receiver and a known reference point.

Summary of the Invention A location determination service receives a request to determine a relative position between a first and second user or the relative position between the first or second user and a known reference point. In one embodiment, each of the first and second users has a location detection device that receives GPS signals from a number of GPS satellites. The GPS signals received by the location detection devices are forwarded to the location determination service that calculates the position of the location detection devices and calculates the relative position between the two location detection devices. The relative position information is then sent back to the first or second users via a communication link.

In another embodiment of the invention, the location determination system calculates the relative position of a location detection device carried by the second user and a known reference point. The relative location information is transmitted back to the first or second user via a communication link.

Brief Description of the Drawings The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:

FIGURE 1 is a block diagram of a location determination system that calculates the relative position of two GPS receivers and forwards the relative position information to a requestor according to a first embodiment of the present invention; and

FIGURE 2 is a block diagram of a location determination system that calculates the relative position of a GPS receiver and a reference point and forwards the relative position information to a requestor in accordance with another embodiment of the present invention. Detailed Description of the Preferred Embodiment

FIGURE 1 illustrates a first embodiment of a relative location determination system according to the present invention. In this embodiment, a first user 10 of the system wishes to know their relative location with respect of a second user 12. For example, the first user 10 may be a parent and the second user 12 may be a child who has wandered off in an amusement park. Alternatively, the first user 10 may be an emergency service provider and the second user 12 may be a victim requiring aid.

To provide the first user 10 with an indication of their relative location with respect to the second user 12, each user has a GPS-based location detection device 14, 16 that includes a GPS satellite receiver and a two-way communication device such as a two-way pager or cellular telephone. An example of a suitable location detection device is set forth in U.S. Patent Application Serial No. 09/535,932, which is herein incorporated by reference. The location detection devices 14, 16 receive GPS signals from one or more overhead GPS satellites 20 and have the ability to communicate with a location determination service 30 via a wireless communication link such as a two-way paging service 32 or cellular telephone service.

When the first user 10 (i.e., a requestor) wishes to determine their relative location with respect to the second user 12, the first user activates their location detection device 14. The location detection device 14 forwards the GPS signals received from the GPS satellites 20 to the location determination service 30 (such as that provided by loc8.net, the assignee of the present application) via the wireless communication link along with an identifier for the second user. The location detection service 30 then generates a page or call to the location detection device 16 carried by the second user 12 asking it to return the GPS signals it receives from the GPS satellites 20. With the GPS signals received from the location detection devices 14, 16 of the requestor and the second user respectively, the location determination system 30 calculates the latitude/longitude of the first user 10 and second user 12. The latitude/longitude information is then forwarded to GIS layer and data software 36. The GIS layer and data software 36 such as that provided by Objectfx of St. Paul, Minnesota, calculates the relative position of the first and second users 10, 12 from the latitude/longitude information provided. The relative position information calculated by the GIS software is forwarded by the location determination service 30 to the requestor's location detection device 14, which displays it for the user. The information may be formatted as a written description such as "[the second user] is located 35 feet northwest of your current location." Alternatively, if the location detection device has an electronic compass, the relative position information may be displayed as an arrow or other icon that points in the direction of the second user 12. In addition, the location determination service 30 may transmit a message to the location detection device of the second user 12 to alert them that someone is looking for them.

To increase the accuracy of the relative location information provided by the location determination service 30, the location determination service may communicate with a differential GPS system 34 that corrects for errors in the signals transmitted from the GPS satellites. Finally, the location determination service 30 may communicate with a 911 service 38 if it is desirable to forward the relative position information to emergency personnel.

An alternate embodiment of the present invention transmits the relative position of a user with respect to the known position of a fixed object. With this embodiment, the first user 10 or requestor does not need to have a location detection device that includes a GPS receiver. As shown in FIGURE 2, the first user 10 has a cellular telephone 50 or other communication that allows user to contact the location determination service 30 via a wireless, landline or computer communication link. The user 10 uses the communication device 50 to access a location determination service 30, which generates a wireless message to a second user 12 who does have a location detection device 16. Upon receipt of the message from the location determination service 30, the location detection device 16 forwards the GPS signals it receives from the GPS satellites 20 back to the location determination service 30. The location determination service 30 calculates the relative position of the second user 12 with respect to a known position of an object or landmark.

For example, if the users 10 and 12 are at a theme park, including a prominent statue 56, the location determination service 30 may calculate the relative location of the second user 12 with respect to the known position of the statue 56. Once the relative position information is calculated, it is transmitted back to the first user 10 via the communication link used to access the location determination system 30. The first user 10 then receives a message such as "[The second user] is located 35 feet northwest of the chicken statue 56 at the entrance of the park." In this embodiment, the location determination service 30 has access to a database 58 including the known latitude/longitude position of one or more prominent landmarks in the neighborhood of the current position of the user 10.

If the first user has a location detection device, the GPS signals received by the device may be forwarded to the location determination service 30 at the time the relative position information is requested. The GPS signals allow the location determination service 30 to determine which prominent landmarks are near the current location of the user 10. However, if the first user 10 does not have a location detection device that can determine its own location, the user will have to use another method of providing this information to the location determination service. This may include selecting a location from a menu or list (if accessing the location determination service with a computer via a data communication link), speaking with a human operator or interacting with a voice response unit (VRU) at the location determination service if accessing the location determination service via a telephonic communication link. Alternatively, the nearest land mark can be determined based on the GPS signals received from the location detection device associated with the second user. Wl ile the preferred embodiment of the invention has been illustrated and described, it will be appreciated that various changes can be made therein without departing from the scope of the invention. For example, in the embodiments disclosed, the location detection devices 14, 16 forward the GPS signals received to the location determination service 30 for calculating the latitude/longitude of their current positions. However, depending on the processing power available at the location detection devices, they may calculate their own latitude/longitude and forward the calculated latitude/longitude to the location determination service in order to calculate the relative positions. Similarly, the present invention may be used to calculate a user's relative position with respect to more than one other individual or object. For example, a member of a SWAT team may want to know his or her relative position with respect to every other member of the team. In that case, the location determination service receives GPS signals from location detection devices carried by each team member and calculates the positions and returns the relative position information to the requestor and the team members, if desired.

Another use of the present invention is to track the location of movable objects. For example, a physician may need to know where a particular piece of emergency equipment is located. To provide this information, the equipment includes a location detection device. When the physician needs to know where the equipment is located, he or she contacts the location determination service with an indication of what piece of equipment they are looking for. The location determination system then initiates a page or call to the location detection device associated with the desired piece of equipment. The GPS signals received from the location detection device are used to calculate the position of the equipment with respect to known locations at a hospital etc. The location determination service then returns the relative location information back to the requestor in a form like "The defibrillator is located 10 feet southwest of the ICU entrance."

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A system for determining a relative position between a first and second user, comprising: a first and second location detection device associated with the first and second users, the location detection devices including a GPS receiver and a two-way communication device; a location determination service that receives a request from the first user to determine the relative position between the first and second user, the location determination service receiving location information from the location detection devices associated with the first and second users and calculating a relative position between each of the location detection devices, the location determination services forwarding the relative position information to the first and/or second user.

2. The system of Claim 1, wherein the location determination service calculates a location of the first and second location detection device from the location information received and provides the calculated locations to a GIS layer and data service that calculates the relative position information.

3. The system of Claim 1, wherein the location determination service receives GPS signals as the location information from the location detection devices.

4. The system of Claim 1, wherein the location determination service receives calculated latitude/longitude coordinates as the location information.

5. A system for determining a relative position between a user and a known reference point, comprising: a location detection device associated with the user, the location detection device including a GPS receiver and a two-way communication device; a location determination service that receives a request to determine the relative position of the user and a fixed object, the location determination service requesting the location detection device to return location information so that the location detection service may calculate the relative position of the location detection device and return the relative position information to a requestor.

6. The system of Claim 5, wherein the location determination service receives an indication of a geographic location in which the user is located and accesses a database including the positions of one or more fixed objects at the geographic location against which the relative position information is calculated.

7. The system of Claim 5, wherein the location determination service receives GPS signals as the location information from the location detection device.

8. The system of Claim 5, wherein the location determination service receives calculated latitude/longitude coordinates as the location information.

9. A system for determining the relative location of an object and a known reference point, comprising: a location detection device including a GPS receiver and two-way communication device that is located with the object; a location determination service that receives a request to locate the object and transmits a signal to the location detection device to return location information, the location determination service receiving the location information from the location determination device on a wireless communication link and computing a relative location of the object with respect to one or more reference points and returning the relative location information to a requestor.

10. The system of Claim 9, wherein the signal is transmitted to the location detection device and location information is received over a two-way paging channel.

11. The system of Claim 9, wherein the location determination service is coupled to a database containing position information for a number of reference points.