Absolute position tracker

• US 5,812,257 A
• Filed: 10/06/1993
• Issued: 09/22/1998
• Est. Priority Date: 11/29/1990
• Status: Expired due to Fees

• Current Assignee: VPL Newco, Inc.
• Original Assignee: Sun Microsystems Incorporated (Oracle Corporation)
• Inventors: Teitel, Michael A., Grimaud, Jean-Jacques G.
• Primary Examiner(s): Issing, Gregory C.
• Application Number:
  US08/165,046
• Time in Patent Office: 1,812 Days
• Field of Search: 342/450, 342/463-5, 342/417, 342/449, 342/387, 342/457, 342/451, 356/139.03, 356/3.1, 356/3.11, 356/3.12, 356/141.4, 356/147, 356/141.5, 356/152.1, 348/53, 345/8, 364/516
• US Class Current: 356/141.4
• CPC Class Codes: G01S 13/874 Combination of several systems for attitude determination in general G01C, control of attitude G05D1/49
• CPC Class Codes: G01S 13/876 Combination of several spaced transponders or reflectors of known location for determining the position of a receiver G01S13/874 takes precedence
• CPC Class Codes: G01S 7/06 Cathode-ray tube displays or other two dimensional or three-dimensional displays

Abstract

A position tracker wherein a base unit scans a selected path with electromagnetic signals. A remote unit whose position relative to the base unit is to be detected includes a sensor for detecting the signals from the base unit. When the scanning signals are detected by the remote unit, the remote unit transmits a response signal to the base unit. The base unit may calculate the angular position of the remote unit relative to the base unit by comparing the time intervals between successive response signals. By locating multiple base units in different positions, the position of the remote unit along multiple coordinate axes may be determined. By adding multiple sensors and response transmitters to the remote unit, the roll, pitch and yaw of the remote unit also may be calculated.

Claims

1. A system for a user to interact with a virtual object, comprising:

a head-mounted display for immersing the user in a virtual scene which includes the virtual object;

a graphics processing unit coupled to the display, wherein the graphics processing unit is configured to render the virtual scene on the head-mounted display;

a calculating device configured to execute a virtual reality program, wherein said virtual reality program-utilizes a position of the user and a position of the virtual object in order to generate graphical information representative of the virtual scene, and wherein said calculating device is configured to convey said graphical information to said graphics processing unit for rendering; and

a position tracker, connected to the calculation device, which informs the calculating device of the position of the user, comprising;

a first base light signal unit comprising;

a first base line signal sensor;

a first base light signal source for emitting a first base light signal which scans a first path in a first plane;

a second base light signal unit comprising;

a second base light signal sensor;

a second base light signal source for emitting a second base light signal which scans the first path;

a third base light signal unit comprising;

a third base light signal sensor;

a third base light signal source for emitting a third base light signal which scans a second path in a second plane, the second plane being generally perpendicular to the first plane;

to a first remote light signal unit comprising;

first remote light signal sensing means for sensing the first, second and third base light signal units;

first light signal identifying means, coupled to the first remote light signal sensing means, for identifying the sensed first, second and third base light signals;

first response means, coupled to the light signal identifying means, for emitting a first response light signal toward the first base light signal unit in response to the first base light signals, for emitting a second response light signal toward the second base light signal unit in response to the second base light signals, and for emitting a third response light signal toward the third base light signal unit in response to the third base light signals;

a second remote light signal unit comprising;

second remote light signal sensing means for sensing the first, second and third base light signals emitted by the first, second and third base light signal units;

second light signal identifying means, coupled to the second remote light signal sensing means, for identifying the sensed first, second and third base light signals;

second response means, coupled to the second light signal identifying means, for emitting a fourth response light signal toward the first base light signal unit in response to the first base light signals, for emitting a fifth response light signal toward the second base light signal unit in response to the second base light signals and for emitting a sixth response light signal toward the third base light signals;

a third remote light signal unit comprising;

third remote light signal sensing means for sensing the first, second and third base light signals emitted by the first, second and third base light signal units;

third light signal identifying means, coupled to the third remote light signal sensing means, for identifying the sensed first, second and third base light signals;

third response means, coupled to the third light signal identifying means, for emitting a seventh response light signal toward the first base light signal unit in response to the first base light signals, for emitting an eighth response light signal toward the second base light signal unit in response to the second base light signals, and for emitting a ninth response light signal toward the third base light signal unit in response to the third base light signals;

first base angle calculating means, coupled to the first base light signal unit, for calculating the angle of the first remote light signal unit along the first plane in response to the first response light signals, for calculating the angle of the second remote light signal unit along the first plane in response to the fourth response light signals, and for calculating the angle of the third remote light signal unit along the first plane in response to the seventh response light signals;

second base angle calculating means, coupled to the second base light signal unit, for calculating the angle of the first remote light signal unit along the first plane in response to the second response light signals, for calculating the angle of the second remote light signal unit along the first plane in response to the fifth response light signals, and for the calculating the angle of the third remote light signal unit along the first plane in response to the eighth response light signals;

third base angle calculating means, coupled to the third base light signal unit, for calculating the angle of the first remote light signal unit along the second plane in response to the third response light signals, for calculating the angle of the second remote light signal unit along the second plane in response to the sixth response light signals, and for calculating the angle of the third remote light signal unit along the second plane in response to the ninth response light signals;

first remote position calculating means, coupled to the first and second base angle calculating means, for calculating the position of the first, second and third remote light signal units along a first base axis in the first plane;

second remote position calculating means, coupled to the first and second base angle calculating means, for calculating the positions of the first, second and third remote light signal units along a second base axis in the first plane, the second base axis being generally perpendicular to the first base axis;

third remote position calculating means, coupled to the third base angle calculating means, for calculating the positions of the first, second and third remote light signal units along a third base axis in the second plane, the third base axis being generally perpendicular to the first and second base axes.

2. The system according to claim 1, wherein the first and second remote signal units are disposed on a remote axis, the position tracker further comprising:

yaw orientation calculating means, coupled to the first and second remote position calculating means, for calculating the yaw orientation of the remote axis.

3. The system according to claim 2, wherein the position tracker further comprises:

pitch orientation calculating means, coupled to the first, second and third remote position calculating means, for calculating the pitch orientation of the remote axis.

4. The system according to claim 3, wherein the third remote signal unit is disposed off the remote axis, the position tracker further comprising:

roll orientation calculating means, coupled to the first, second and third remote position calculating means, for calculating the roll orientation of the remote axis.