Untethered position tracking system

• US 6,720,876 B1
• Filed: 02/14/2002
• Issued: 04/13/2004
• Est. Priority Date: 02/14/2002
• Status: Active Grant

• Current Assignee: Vulcan Patents LLC
• Original Assignee: Interval Research Corporation
• Inventors: Burgess, David A.
• Primary Examiner(s): La, Anh
• Application Number:
  US10/076,938
• Time in Patent Office: 789 Days
• Field of Search: 340/568.1, 340/539.13, 340/10.1, 340/573.1, 340/3.51, 340/325.36, 340/505, 340/825.49, 340/988, 340/992, 340/994, 342/357, 342/463, 342/357.07, 367/903, 367/904, 367/197-199
• US Class Current: 340/568.1
• CPC Class Codes: G01S 11/14 using ultrasonic, sonic, or infrasonic waves
• CPC Class Codes: G01S 5/0289 of multiple transceivers, e.g. in ad hoc networks
• 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

The invention can enable the position (i.e., location and/or orientation) of one or more untethered objects to be tracked. One or more transmitters, each of which has a fixed and known positional relationship to a corresponding object, each emit a sequence of position tracking signals. Each transmitter can emit a unique, identifiable position tracking signal so that the transmitter (and the object to which the transmitter is coupled) from which a signal was emitted can be identified, thereby enabling the position of multiple objects to be tracked. Multiple receivers receive the position tracking signals emitted by each transmitter. The receivers record the times at which signals are received. These recorded times can be communicated to a controller, which can determine from the recorded times the location of each object at a time that a position tracking signal was emitted from the corresponding transmitter. If multiple transmitters are coupled to each object, the orientation of the object can be determined in addition to the location. The position tracking signals can advantageously be ultrasonic signals, which require relatively little power, thus enabling the transmitters to be embodied in a physically small device, so that correspondingly small objects can be tracked. The invention can be used to track objects in small and medium-scale tracking spaces and can be adapted to track the position of an object or objects in one, two or three dimensions. An inertial device can be added to the object, in addition to the transmitter, to enhance the tracking of the object'"'"'s location.

Claims

1. A system for tracking the position of multiple objects, comprising:

a plurality of transmitters each adapted to emit a sequence of position tracking signals, wherein the position tracking signals emitted by a particular transmitter of the plurality of transmitters can be identified as having been emitted by that transmitter, and wherein each of the plurality of transmitters is coupled to a corresponding one of the objects so that the transmitter maintains a fixed and known positional relationship to the object, each of the plurality of transmitters further comprising;

a clock that is synchronized in time with respect to the clock of each other transmitter of the plurality of transmitters; and

means for synchronizing the emission of a signal with the emission of a signal by each other transmitter of the plurality of transmitters;

a plurality of receivers each adapted to receive position tracking signals emitted by a transmitter, the receipt of a position tracking signal constituting a detection event, wherein each of the plurality of receivers is coupled to a corresponding one of the objects so that the receiver maintains a fixed and known positional relationship to the object, each of the plurality of receivers further comprising;

a clock that is synchronized in time with respect to the clock of each other receiver of the plurality of receivers;

means for recording the time of a detection event based upon the time of the clock;

means for identifying the transmitter associated with the detection event; and

means for communicating with a controller, wherein one or more recorded times of a detection event and the identity of the associated transmitter can be communicated to the controller;

a controller, comprising;

means for communicating with each of the plurality of receivers, wherein recorded times of detection events and the identities of the associated transmitters can be communicated from each of the plurality of receivers; and

means for determining, based upon the recorded times of detection events and identities of the associated transmitters, positions of the objects;

a plurality of inertial devices, each of the plurality of inertial devices adapted to obtain inertial tracking information and coupled to one of the objects, each of the plurality of inertial devices further comprising;

means for communicating with a transmitter coupled to the same object, wherein the inertial tracking information can be communicated from the inertial device to the transmitter; and

means for communicating with a controller, wherein position information can be communicated from the controller to the inertial device; and

wherein;

each transmitter coupled to an object together with an inertial device is adapted to emit position tracking signals that can include inertial tracking information obtained by the inertial device and further comprises means for communicating with the inertial device, wherein inertial tracking information can be communicated from the inertial device to the transmitter;

each of the plurality of receiver'"'"'s means for communicating with a controller can also communicate inertial tracking information, if any, to the controller;

the controller'"'"'s means for communicating the receivers can also enable inertial tracking information to be communicated from the receivers;

the controller'"'"'s means for determining can determine a position of an object based on inertial tracking information; and

the controller further comprises means for communicating with an inertial device, wherein position information determined using the recorded detection events can be communicated to the inertial device.

2. A system as in claim 1, wherein a pair of transmitters are coupled to each object, the controller further comprising means for determining, based upon the recorded times of detection events and the identities of the associated transmitters, the orientation of one or more of the objects.

3. A system as in claim 1, wherein the plurality of receivers comprises at least two receivers and the plurality of transmitters comprises at least two transmitters, whereby the system can track the positions of the objects.

4. A system as in claim 1, wherein the position tracking signals are ultrasound signals.