Detection system for determining positional and other information about objects

• US 6,493,649 B1
• Filed: 07/12/1999
• Issued: 12/10/2002
• Est. Priority Date: 12/04/1996
• Status: Expired due to Fees

• Current Assignee: AT&T Istel (Bayerische Motoren Werke AG)
• Original Assignee: AT&T Laboratories-Cambridge Limited (AT&T, Inc.)
• Inventors: Jones, Alan Henry, Ward, Andrew Martin Robert
• Primary Examiner(s): Bui, Bryan
• Application Number:
  US09/319,047
• Time in Patent Office: 1,247 Days
• Field of Search: 702/150, 702/152, 702/153, 702/155, 702/159, 702/94-95, 340/10.4, 340/825.08, 340/825.57, 340/825.69, 340/505, 340/539, 342/450, 342/458, 367/93, 367/99
• US Class Current: 702/150
• CPC Class Codes: G01S 11/16 using difference in transit time between electrical and acoustic signals
• CPC Class Codes: G01S 13/878 Combination of several spaced transmitters or receivers of known location for determining the position of a transponder or a reflector G01S13/874 takes precedence
• CPC Class Codes: G01S 15/872 Combination of several systems for attitude determination using inertial means G01C9/00, control of attitude G05D1/49
• CPC Class Codes: G01S 15/876 Combination of several spaced transmitters or receivers of known location for determining the position of a transponder or a reflector G01S15/872 takes precedence
• CPC Class Codes: G01S 5/186 Determination of attitude using inertial means G01C9/00; control of attitude G05D1/49
• CPC Class Codes: G01S 5/30 Determining absolute distances from a plurality of spaced points of known location

Abstract

A system for determining the position of each of a plurality of objects in a specified environment by determining the transit times of slowly propagating measurement energy transmitted from a measurement energy transmitter on each object to a plurality of fixed measurement energy receivers in the specified environment, the transmission of the measurement energy being triggered by a burst of high speed propagating trigger energy into the specified environment from a trigger energy transmitter, the measurement energy transmitter on each object being triggered by an object-mounted trigger energy receiver, each burst of trigger energy being encoded so as to trigger one only of the measurement energy transmitters, wherein a coordinating control system determines the order in which the measurement energy transmitters are triggered, in response to updatable information relating to service demands of the trigger energy transmitter and/or objects.

Claims

1. A system which enables the position of each of a plurality of labelled objects in a specified environment to be determined by determining the transit time of slowly propagating energy transmitted from a transmitter of slowly propagating energy on each labelled object to a plurality of receivers positioned at fixed points in or around the specified environment, and computing therefrom the actual distance of the transmitter from the receivers, wherein the transmission of the slowly propagating energy is initiated by a burst of high speed propagating energy from a master transmitter of high speed propagating energy located so as to cause transmitted bursts of such high speed energy to enter said environment, the transmitter of high speed propagating energy on each object being controlled by an object mounted receiver adapted to respond to an appropriately encoded burst of such high speed energy, each said burst being encoded so as only to be responded to by one of the object mounted receivers (each transmitter/receiver combination being referred to as a transponder), to thereby initiate a burst of slowly propagating energy from the transponder, wherein the burst originating transponder location is identifiable from the encoding of the transmission which triggers that transponder and the burst is of just sufficient duration to provide a response at the receivers and in order to allow the system to adapt to different numbers of transponders and different demands for service, and a coordinating control system is provided for determining the order in which the object mounted transmitters are to be triggered by the encoded transmissions from the master transmitter, in response to updatable information relating to the service demands of the transmitter and/or transponders and/or objects.

2. A system as claimed in claim 1, wherein the encoding of the high speed energy transmission enables a plurality of different slow speed signal transmitters all located in the same specified environment to be triggered in turn, so that during a sequence of time windows, position data relating to each of the slow speed signal transponder transmitters in the environment can be obtained, the data in each window relating specifically to only one of the object mounted transducer transmitters.

3. A detection system for determining information concerning at least the position of an object, using signal pulses respectively of high and slow propagation speeds for use in a system as claimed in claim 1, comprising at least three fixed, non-colinear, distributed slow speed signal responsive receivers, at least one transmitter unit for transmitting slow speed signal pulses, mounted on the object, means for generating and transmitting high speed signal pulses to synchronise slow speed signal pulse transmission from the transmitter with the commencement of a reception sensitive period at a receiver, and means for computing signal pulse reception times and correlating differences therein to determine the required information about the position of the object.

4. A detection system as claimed in claim 3, further comprising a coordinating device to address the object mounted transmitters, as by sending address information to them as part of a regular time synchronisation signal.

5. A system as claimed in claim 1 wherein a bi-directional link is provided between the coordinating control system and each transponder receiver by adding a second transmitter to each transponder receiver and adding a compatible receiver to the coordinating control system, such transponders being referred to as bi-directional transponders, whereby the latter are enable to transmit data to the coordinating control system.

6. A system as claimed in claim 1, wherein each transponder further includes input and output facilities.

7. A system for determining the position of an object in a specified environment, in which the transit time is determined of slowly propagating measurement energy transmitted from a transmitter on the object to a plurality of receivers positioned at fixed points in or around the specified environment, and in which the distance of the transmitter from each receiver is computed from the times taken for the measurement transmission to propagate from the object to some of the receivers, and wherein the slowly propagating measurement energy is initiated by a trigger burst of energy having a higher speed of propagation from a master transmitter of high speed propagating energy which is located so as to transmit trigger bursts into the environment to initiate the measurement energy transmitter on the object of interest, and wherein a plurality of such transmitters are located on different objects and/or points of the same object, within the environment, and each transmitter of measurement energy is associated with and controlled by signals from a receiver responsive to trigger burst transmissions, and the latter are encoded and/or transmitted at different frequencies so that the receivers located throughout the environment can be individually addressed from the master transmitter, each said combination of a receiver and transmitter being referred to as a transponder, characterised in that a coordinating control system is provided for determining the order in which the object mounted transponder transmitters are to be addressed and triggered by the transmissions from the master transmitter, together with memory means for storing relevant information about the different transponder transmitters by reference to their unique address, by which the order can be determined.

8. A system as claimed in claim 7, wherein the coordinating control system memory means stores a unique address for each of the transponder transmitters and the control system is programmed to encode the transmissions using the address information so as only to address the transponder transmitters individually.

9. A system as claimed in claim 8, in which in addition to the unique address for each transponder transmitter at least one additional item of information (Weighted Hierarchy Information for Schedule Positioning—

or “

WHISP”

is stored in a manner which can be associated with each unique address and the control system is programmed to select from the addresses that of the receiver and transmitter next to be poled using the WHISP values to determine the order of addressing.

10. A system as claimed in claim 9, wherein a WHISP is stored for each unique address and the WHISP is changed to adjust the subsequent addressing of the transponder transmitters.

11. A system as claimed in claim 9, wherein each WHISP comprises two items of information, firstly the length of time since the transponder transmitter was last addressed (which may be continually updated by the clock information) and secondly a rate of interrogation figure to be achieved by the system for that transponder transmitter.

12. A system as claimed in claim 11, wherein the system is programmed to utilise a third item of data within a WHISP and logic circuit means is provided to increase the frequency of tracking of an address of a first object if a second object having such a third item of information stored as part of its WHISP is perceived by the position determination of the second object, to have moved close to the first object.

13. A system as claimed in claim 9, wherein changes to WHISP data occur as a result of a lapse of time, the arrival of a particular time or date, by interaction with an application running on a computer which may be part of the position determining system or the coordinating control system or another computer altogether, or by the entry of data by an operator.

14. A location system which includes a set of ultrasound receivers placed at known positions on a ceiling in a room to detect ultrasonic signals from an ultrasound transmitter attached to an object in the room, and by determining the times of flight of those signals from the ultrasonic transmitter to the ultrasound receivers so calculates the position of that object in the room, wherein the system is extended by a programmable coordinating control system to address more than one ultrasonic transmitter in the room provided each has a unique address so that they can be triggered separately, by serially polling the transmitters in response to control signals from the control system.

15. A method of determining the position and orientation in a specified environment of an object to which a plurality of transponder transmitters are attached at known spaced apart positions comprising the steps of finding the position of each of said plurality of transmitters within the environment and comparing the positions of those transmitters with the coordinates of at least one, and preferably a number of, different known points in said environment, thereby to determine the relative position of the transmitters to the known points, and relating the positions of the transmitters to the object on which they are mounted, to determine its position and orientation of the object relative to the environment.

16. A method as claimed in claim 15, wherein the step of finding the position of each of the plurality of transponder transmitters includes transmitting appropriately encoded trigger signals for reception by a single transponder receiver, said transponder receiver having decoding logic for driving the plurality of transponder transmitters attached to the known spaced apart positions on the object.

17. A method as claimed in claim 16, wherein the step of finding the position of each of the plurality of transponder transmitters includes transmitting a selected one of a plurality of address signals for reception by the transponder receiver, each of the plurality of transponder transmitters being uniquely triggerable by a corresponding one of the plurality of address signals.

18. A system for determining the orientation of an object within an environment defined at least in part by means of a plurality of detectors sensitive to measurement energy and located at a corresponding plurality of known positions therein, wherein transmitter means is mounted on the object which is adapted to transmit measurement energy away therefrom and towards the detectors and has a known position relative to the object, and wherein polling means is provided for interrogating the detectors to determine on which if any the transmitted energy has been incident and for computing the straight line distances from the object to the detectors and thereby determining the position of the object in said environment characterised in that by using the known relationship between the transmitter means and the object, the direction in which the object is facing in terms of the said environment, can also be determined.

19. Method of determining the orientation of an object having a transmitting device mounted at a known position thereon, when located in an environment containing a plurality of detectors sensitive to energy transmitted by said transmitting device and located at known positions in the environment, wherein the object is opaque to the transmitted energy, so that a directional transmission is obtained and wherein the energy is transmitted at a defined point in time and the detectors are interrogated at a later point in time to identify those on which energy has been incident prior to the later point in time, to enable the computation from the transit times to the identified detectors of the straight line distances between the transmitting device and the detectors, further comprising the step of determining the orientation of the opaque object by reference to the pattern of the identified detectors and by reference to the position of the transmitting device relative to the object.