Detection system for determining positional and other information about objects

• US 6,348,856 B1
• Filed: 05/31/2000
• Issued: 02/19/2002
• Est. Priority Date: 12/04/1997
• Status: Expired due to Term

• 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): MULLEN, THOMAS J
• Application Number:
  US09/555,558
• Time in Patent Office: 629 Days
• Field of Search: 340/10.1, 340/825.08, 340/825.57, 340/825.69, 340/505, 340/539, 340/3.51, 340/568.1, 340/572.1, 342/450, 342/458, 367/93
• US Class Current: 340/10.1
• CPC Class Codes: G01S 11/16 using difference in transit time between electrical and acoustic signals
• CPC Class Codes: G01S 13/74 Systems using reradiation of radio waves, e.g. secondary radar systems; Analogous systems
• CPC Class Codes: G01S 13/86 Combinations of radar systems with non-radar systems, e.g. sonar, direction finder
• CPC Class Codes: G01S 15/74 Systems using reradiation of acoustic waves, e.g. IFF, i.e. identification of friend or foe
• CPC Class Codes: G01S 15/86 Combinations of sonar systems with lidar systems; Combinations of sonar systems with systems not using wave reflection
• 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 5/14 Determining absolute distances from a plurality of spaced points of known location
• CPC Class Codes: G01S 5/30 Determining absolute distances from a plurality of spaced points of known location
• CPC Class Codes: G01S 7/521 Constructional features
• CPC Class Codes: G08G 1/20 Monitoring the location of vehicles belonging to a group, e.g. fleet of vehicles, countable or determined number of vehicles

Abstract

A system for determining the position of a labelled object within an environment containing a plurality of detectors sensitive to energy of a first type and located at known positions therearound, wherein the object has a transmitter for transmitting energy of the first type, and each object is labelled by means of a receiver forming part of a communication link with a remote controlling transmitter for triggering the object-mounted transmitter. The transit time between the transmitter and each detector is used to determine the straight line distances between the object and the receivers, to enable the position of the object relative to the receivers to be determined. The arrival and departure of an object into and from the environment is determined by a second communication link from a second transmitter on each object, to a remote receiver. The two communication links may be combined in a bi-directional radio communication system. Computing means is provided to associate the time information with the receivers from which the times have been obtained to generate a transit time to each receiver, and the high speed energy transmissions may be encoded so that a plurality of different transmitters, all located in the same specified environment, can be triggered in turn. Typically the slow speed signals are acoustic or ultrasonic signals and the high speed signals are electric currents, voltages, electromagnetic radiation such as IR, UV or radio signals.

Claims

1. A system determining the position of an object within an environment defined at least in part by means of a plurality of receivers of energy of a first type, the receivers being located in a corresponding plurality of known positions around the object, wherein the object has associated therewith a transmitter for transmitting from the object to the receivers energy of the first said type, the object having associated with the transmitter of energy of the first said type a receiver forming part of a communication link with a remote controlling transmitter for triggering the object-mounted transmitting means, and the transit time between the latter and each receiver is used to determine the straight line distances between the object and the receivers to enable the position of the object relative to the receivers to be determined, characterised in that the arrival and departure of the object into and from the environment is determined by a second communication link from a second transmitter associated with the object and a remote receiver.

2. A system as claimed in claim 1, wherein the two communication links are combined in a bi-directional radio communication system.

3. A system as claimed in claim 1, in which the position of each of a plurality of objects in a specified environment is determined by determining the transit time of slowly propagating energy transmitted from a transmitter on each 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 remote controlling transmitter located so as to cause transmitted bursts of such high speed energy to enter the said environment, and wherein the transmitter on each object is associated with a receiver adapted to respond to an appropriately encoded burst of such high speed energy, to thereby initiate a burst of slowly propagating energy, and wherein a further transmitter of high speed energy is provided on each object, associated with the receiver thereon, to transmit data signals to a remote receiver using encoded high speed energy transmission.

4. A system as claimed in claim 3, wherein each of the said plurality of receivers is adapted also to be responsive to a said burst of high speed energy, so as to identify the beginning of a window of time within which a slow speed energy burst may arise and be received thereby.

5. A system as claimed in claim 4, wherein the burst is the same burst as is sent to trigger a transmitter on one of the plurality of objects to transmit a slowly propagating wave, for time measurement.

6. A system as claimed in claim 4, wherein the said plurality of receivers are connected by a network of cables and the transmission of the reset signals and the polling of the time values is achieved via the network.

7. A system claimed in claims 4, wherein the receivers include a latch to retain information about the time at which the beginning of a burst of slow speed energy is received after the beginning of each said window of time.

8. A system as claimed in claim 7, wherein the receivers are so as to recover the time information and reset the latches.

9. A system as claimed in claim 8, wherein computing means is provided to associate the time information with the receivers from which the times have been obtained, and generate a transit time to each receiver.

10. A system as claimed in claim 9, wherein the computing means is programmed to convert the transit times into distance values, and by using position data relating to the receivers stored in the computing means to compute therefrom the position of the object mounted transmitter relative to each of the receivers, and therefore, by geometry its position relative to one or more fixed points defining the specified environment.

11. A system as claimed in claim 3, wherein the slow speed signals are acoustic or ultrasonic signals and the high speed signals are electric currents or voltage or visible or invisible electromagnetic radiation.

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

13. A system as claimed in claim 12, wherein encoding of the high speed signals is by way of frequency, or amplitude, or phase, modulation;

or pulse coding;

or any combination thereof.

14. A system as claimed in claim 13, wherein digital encoding techniques are employed.