Optics: image projectors – Projected image combined with real object
Reexamination Certificate
2000-04-19
2003-04-15
Adams, Russell (Department: 2851)
Optics: image projectors
Projected image combined with real object
C353S122000, C359S196100, C359S201100, C359S202100, C372S024000
Reexamination Certificate
active
06547397
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to 3D imaging using a laser projector. Particularly, the present invention relates to a rapidly scanned laser system that accurately identifies locations on an object. More particularly, the present invention relates to a rapidly scanning laser system utilizing a three-dimensional data set projected onto contoured surfaces. Even more particularly, the present invention relates to a rapidly scanning laser system utilizing a three-dimensional data set projected onto contoured surfaces that incorporates a laser range-finding system for accurately determining the distance to the contoured surfaces.
2. Description of the Prior Art
Laser projectors are used to project images onto surfaces. They are utilized to assist in the positioning of work pieces on work surfaces. More recent systems have been designed to project three-dimensional images onto contoured surfaces rather than flat surfaces. The projected images are used as patterns for manufacturing products and to scan an image of the desired location of a ply on previously placed plies. Examples of such uses are in the manufacturing of leather products, roof trusses, airplane fuselages and the like. Laser projectors are also used for locating templates or paint masks during the painting of aircraft. A rapidly scanning laser system is a laser spot that moves from location to location with sufficient speed to appear as a continuous line.
The use of a scanned laser image to provide an indication of where to place work piece parts requires extreme accuracy in calibrating the position of the laser projector relative to the work surface. In the past, the systems have typically required the placement of several reference points fixed on or about the work surface. Typically, six reference points were required for sufficient accuracy. Reflectors or sensors have typically been placed in an approximate area where the ply will be placed. Since the points are at fixed locations relative to the work and the laser, the laser also knows where it is relative to the work. The requirement of six fixed reference points has been somewhat restricting in systems used for airplane fuselages. The plies and jobs utilized to attach the plies onto the airplane fuselage are very large. The reference points must be placed at locations where the plies will not cover the reference points. The use of the fixed points has thus been somewhat difficult to achieve. Furthermore, technicians are required to travel to the workplace and accurately place the fixed reference points.
To use a laser-pointing device in a high-accuracy, high-precision application, it must be positioned very accurately over a work piece or tool if it is to illuminate points on the work piece accurately. In one known technique called resectioning, a designator automatically determines its position and orientation relative to a tool by measuring the angles to three or more fiducial points on the tool. A designator is a device similar in concept to a laser light projector, but operating at a higher precision. It is used to sweep a laser beam over a surface to illuminate a curve. A fiducial point is an optical device whose position is accurately known in three dimensions. The tool is brought roughly into position with respect to the designator, for instance to within six inches. The designator, or other external optical devices, are used to sense the fiducial points (a minimum of four), and to measure the angles from the designator to them, not the distance from the designator to the tool. This is done to accurately orient the spatial and angular position of the designator with respect to the tool.
However, the designator cannot designate points accurately if the beam deflection angles cannot be controlled accurately. Resectioning also cannot be accurate if the galvanometers cannot accurately measure spatial angles to the fiducial points. One problem is that the components of the designator are subject to a number of sources of imprecision. These include non-linearities in the galvanometer response and the position detectors, differences in gain in op-amps driving the galvanometers, bearing run-out, tolerance in the mounting of galvanometers in the designator, twist or wobble in the galvanometer shafts, mirrors mounted slightly off axis, variations in mounting of the laser or other beam-steering elements, etc.
U.S. Pat. No. 5,400,132 (1995, Pierre Trepagnier) discloses an improved method of compensating for errors in a laser pointing device, especially in three-dimensional applications, by accurately controlling the angle that the laser beam makes in space. This is called rectification. In the method, the laser-pointing device is established in an accurate angular relationship to at least four fiducial points. The angular errors internal of the designator are determined by comparing actual galvanometer inputs, assuming no error in the established angular relationship. The actual galvanometer inputs are those that aim the laser beam at the fiducial points while recognizing the existence of the internal errors. The nominal galvanometer inputs are those that would aim the laser beam at the fiducial points assuming no internal errors in the laser pointing device. The angular errors are stored in a form for use during scanning by the laser pointing device to compensate for the internal errors in converting nominal direction numbers computed by a control to actual galvanometer inputs. A major drawback of this system is that a minimum of four fiducial points is required, but preferably six points, to properly project the image, or the distance to the points must be accurately known.
More recently, there has been disclosed a system in which reference points can be placed at initially unknown locations about a workplace. However, the laser is able to determine the specific location of the unknown locations of the reference points provided that at least one variable is fixed. U.S. Pat. No. 5,757,500 (1998, Kurt Rueb) discloses a system that utilizes two reference points which are spaced by a fixed distance. The system is able to calibrate its location in space and relative to the work piece by determining the angular location of the unknown locations for the reference points. The known distance between the two reference points is then relied upon to fix the location of all reference points in space and the location of the laser projector.
In all of the prior art devices, one variable must be fixed. In some, it is required that the distance between the laser projector and the work piece platform be known and fixed. This represents the “z” axis in a three-dimension (x-y-z) system. Not knowing the distance between the laser projector and the work piece requires these prior art systems to triangulate a plurality, usually at least six, of known reference points to correctly projecting the laser image upon the work piece. In other systems, it is required that the distance between two reference points on the work piece platform be known and fixed.
In addition, all prior art devices require that the tool or object onto which an optical template is to be projected requires the object or tool to contain reference data marks. These reference data marks are based on ship set coordinates and are located using theodolites or laser tracker. A theodolite is extremely expensive piece of equipment, approximately $250,000. They are capable of five-decimal point accuracy in determining the coordinates of the reference marks. For painting template applications, 5-decimal point accuracy is unwarranted. Thus the cost of buying a theodolite cannot be justified.
Therefore what is needed is a 3D imaging system utilizing a three-dimensional data set projected onto contoured surfaces where the distance between the laser projector and the work piece platform does not need to be known. What is further needed is a 3D imaging system utilizing a three-dimensional data set projected onto contoured surfaces that can determine the distance between t
Kaufman Steven P.
Savikovsky Arkady
Adams Russell
Edwards & Angell LLP
Koval Melissa J
Laser Projection Technologies, Inc.
Manus Peter J.
LandOfFree
Apparatus and method for projecting a 3D image does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Apparatus and method for projecting a 3D image, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Apparatus and method for projecting a 3D image will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3100447