Computer graphics processing and selective visual display system – Display peripheral interface input device – Cursor mark position control device
Reexamination Certificate
1999-05-20
2002-07-09
Hjerpe, Richard (Department: 2674)
Computer graphics processing and selective visual display system
Display peripheral interface input device
Cursor mark position control device
C345S157000, C345S159000, C345S162000, C345S166000, C345S207000
Reexamination Certificate
active
06417839
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a system for position and orientation determination of a point in space using scanning laser beams. The present invention has applications in such diverse areas as medicine, aerospace and virtual reality systems. Within these realms, the present invention is contemplated for use for position and orientation monitoring of surgical instruments, cockpit-based helmet-mounted sighting mechanisms, and augmented reality computer-aided-design systems, among others.
It is known to measure position and orientation using multiple scanning beams in a reference frame. It is also known to use detection of polarized light in position and orientation measuring systems. However, Applicant is unaware of any system that uses multiple scanning beams, at least some of which are polarized, and detectors, at least some of which are associated with polarizing filters in a position and orientation determination measurement system.
Applicant's prior patent U.S. Pat. No. 5,574,479 (Odell) discloses an optical system for determining the roll orientation of a remote unit relative to a base unit. In Odell, one or more beams are emitted from a fixed base unit. None of these beams is movable in any direction. The beams illuminate the entire work area simultaneously. In Odell, light emanating from the fixed source is polarized and this polarized light is used to determine the roll angle of the remote unit with respect to the base unit through the use of polarization of one or more of the detectors. The fixed emitters of Odell illuminate the entire work area simultaneously which results in the creation of ambient reflections that can alter the sensed angles of incidence of light emanating from the fixed sources due to such reflections occurring off different walls and surfaces of the work area. The present invention differs from the teachings of Odell as contemplating a plurality of rotatable source beams polarized to prescribed degrees with a movable object comprising a photodetector having at least one polarized detector means and wherein orientation including azimuth, elevation and roll may be computed.
U.S. Pat. No. 5,767,960 to Orman discloses optical 6D measurement system with three fan-shaped beams rotating around one axis. While Orman does disclose the concept of movable beams of light, Orman fails to teach or suggest the use of angle of polarization or angle of incidence as a means to facilitate accurate measurements of orientation.
SUMMARY OF THE INVENTION
The present invention relates to a system for position and orientation determination of a point in space using scanning laser beams. The present invention includes the following interrelated objects, aspects and features:
(1) In a first aspect, the present invention contemplates a base unit having three scanning laser beam light sources that rotate together emanating from approximately the same point. The resulting beams are fan-shaped. In practice, due to the physical structure of the base unit, these light sources are slightly spaced from one another, however, at distances beyond about 10 cm from the sources, inaccuracies arising from this spacing are small and can be accounted for through knowledge of source positions. (2) Each of the beams is appropriately collimated such that, for example, at one meter distance from the source, the width of the beam is no more than 1 mm. For example, at two meters distance from the source, the beam width does not exceed 2 mm. As explained above, each beam is polarized. Thus, for example, the beams may be polarized at 0° polarization, 45° polarization, and 90° polarization, respectively. Other polarization relationships between the beams may also be suitably employed.
(3) In the preferred embodiment, the beams may rotate quite rapidly, as fast as 90 times per second or 5400 r.p.m. Thus, 90 measurements per second may be taken, thereby resulting in high bandwidth in measurement.
(4) The present invention contemplates a number of different embodiments of detector configuration. In a preferred embodiment, illustrated in
FIG. 3
, three detectors are employed including a first detector that is always exposed to incident light, a second partially shaded polarized detector, and a third partially shaded unpolarized detector.
(5) In a second embodiment, illustrated in
FIG. 5
, three detectors are employed, a first detector that is polarized and always exposed to light, and second and third partially shaded unpolarized detectors.
(6) In a third embodiment, illustrated in
FIG. 6
, three detectors are employed, a first unpolarized detector always exposed to light, a second partially shaded detector polarized in a first orientation, and a third partially shaded detector polarized in a second orientation.
(7) In a fourth embodiment, illustrated in
FIG. 7
, three detectors are employed, a first unshaded, unpolarized detector always exposed to light, a second partially shaded unpolarized detector, and a third partially shaded polarized detector. The third detector is polarized by virtue of a polarization filter mounted on the aperture overlying the detectors.
(8) Concerning each of the embodiments described herein, each position sensing detector may be of a particular design such as those that are disclosed in detail in
FIGS. 8-16
. These position sensing detectors measure the angle of incidence of impinging laser beams and may or may not use polarized beams to measure roll. Thus,
FIG. 8
discloses a position sensing detector (PSD) having a split four quadrant detector and with an aperture allowing light from a source of light to pass therethrough and impinge on the active area of the detector whereupon the position of the light spot on the active area of the detector may be detected and conveyed. The tetralateral position sensing detector of
FIG. 9
is similar to that of
FIG. 8
but includes the further provision of a focusing lens.
(9)
FIG. 10
shows single axis tetralateral position sensing detectors that measure position and angle of incidence in a single plane. Under normal circumstances, a plurality of such detectors would be provided in adjacency to one another for each desired measurement.
(10)
FIG. 11
shows pitch and yaw detecting sawtooth-type position sensing detectors wherein, in each case, two single axis angle of incidence detectors are mounted orthogonally.
FIG. 12
shows different embodiments of position sensing detectors including, in each case, an active area comprised of a coded pattern with an aperture spaced above the active area and also including a coded pattern.
FIG. 13
shows diagrams depicting an intensity resolver aspect of the position sensing detectors of the present invention including depiction of a zone of uncertainty.
(11) The detection of light from the moving beams of light may also employ an auxiliary detector spaced from the other detectors by a known distance sufficient to resolve a position vector connecting position rays to each detector (FIG.
14
). In a further modification, two detectors may be spaced in the manner contemplated in
FIG. 14
with a third spaced detector being used to compute azimuth. If desired, the present invention may be simplified through the use of only two adjacent position sensing detectors which may be employed to determine only one or two degrees of orientation such as, for example, elevation or elevation and roll (
FIGS. 16 and 17
, respectively).
(12) Suitable computer means is employed to control the present invention in its various embodiments. The computer means controls rotation of a motor that rotates the light beams, and a sensor senses motor rotation and provides data indicating motor rotation to the computer means. The computer means controls activation of the light beams and receives data from the sensors which it uses to calculate position and orientation. A display is provided permitting display of position and orientation of a point within a prescribed space.
Accordingly, it is a first object of the present invention to provide a system for position and orientation de
Ascension Technology Corporation
Hjerpe Richard
Spiegel H. Jay
Zamani Ali
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