Optics: measuring and testing – Angle measuring or angular axial alignment – Apex of angle at observing or detecting station
Reexamination Certificate
2000-03-21
2003-02-11
Buczinski, Stephen C. (Department: 3662)
Optics: measuring and testing
Angle measuring or angular axial alignment
Apex of angle at observing or detecting station
C356S004080, C356S141500
Reexamination Certificate
active
06519029
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates in general to the field of position measurement and more particularly to an improved apparatus and method of providing position-related information.
2. Description of Related Art
A variety of techniques are known in the art to measure position, including land surveying techniques and global positioning satellite (“GPS”) system techniques.
Many of these techniques are limited by high cost apparatus often due to the complexity of manufacturing complex devices with high precision and accuracy. Additionally, many of these techniques required extensive training, and therefore are not usable by those not trained in the art.
It is an object of the present invention to provide an improved low cost optical transmitter which overcomes many of the problems associated with prior art position measurement systems.
SUMMARY OF THE INVENTION
The system described in this disclosure contains, at a high level, several transmitters and a receiving instrument. The transmitters transmit signals from their stationary locations and the receivers receive these signals. In the present system, laser beams and LEDs are used as the signals. The receiving instrument then determines a coordinate system and calculates its position and assorted other information of interest from these received signals. The receiving instrument then displays this information through a user interface. The information may be, for example, the location of the receiving instrument or its distance relative to another location.
As is clear from the present disclosure, the present invention can be applied to a variety of different fields, applications, industries, and technologies. The present invention can be used, without limitation, with any system in which information related to position must be determined, including without limitation movement, dimensional measurement, and position and orientation tracking. This includes without limitation many different processes and applications involved in myriad industries. Some of these industries and some of their associated processes or applications are: film making (digitizing models, virtual sets, camera tracking, automatic focusing), construction (trades, power tools, surveying, CAD, equipment control, construction measurement and layout), robotics (robot calibration, work cell configuration, mobile robot navigation, hazardous waste excavation), law enforcement (accident scene mapping, crime scene mapping, incident reconstruction), computers (3D input devices, video games), virtual reality (augmented reality, virtual arcades, 3D Internet experiences), manufacturing (factory automation, facility decommissioning, parts inspection, facility maintenance, manufacturing tooling and inspection, manufacturing measurement), medical (surgical navigation, smart operating rooms, medical instrumentation), and defense (ordnance modeling, simulation training, aircraft fit-checks, ship retrofit and repair, site remediation).
Various figures are included throughout this disclosure to illustrate a variety of concepts, components of several subsystems, manufacturing processes, and assembly of several subsystems.
1. Transmitter
The present invention can be used in conjunction with the techniques and apparatus described in co-pending provisional patent application U.S. Ser. No. 60/104,115 to Pratt, also assigned to the present assignee, filed on Oct. 13, 1998, and incorporated herein by reference. The following description in this section is intended to highlight certain features of the incorporated provisional. Certain attached figures, including the “Rotor/Bearing Housing Assembly” figure, the “Laser Assembly” figure, and the “Asymmetric Pulse Effect” figure, provide additional detail. Additional figures also depict various (i) components of a transmitter, (ii) manufacturing processes for parts of a transmitter, and (iii) operational concepts, including beam fanning, tracking, and mathematics, which are related to a transmitter
A. Simplified Optical Path
As is clear from the incorporated application, one of the key advantages of the Arc Second transmitters is the simplification of the optical paths as exemplified by the lasers rotating with the head. Additionally, there is no window in the preferred transmitter. Therefore, there is no distortion introduced by the movement of the laser beam across a window. As described, the preferred embodiment utilizes a lens or other device which rotates with the laser. Thus, there is no distortion caused, for example, by variable window characteristics or angles of incidence or between a rotating lens and a fixed laser. The absence of a fixed window also simplifies manufacture, maintenance, and operation. The absence of a fixed window does require that a rotating seal be added to the transmitter.
B. Speed of Rotation and Storage of Parameters
As is also described in the incorporated patent application, the rotating head, and the lasers within it, rotate through a full 360 degrees at a constant, although configurable, velocity. Having an easily quantifiable center of rotation simplifies the algorithms for determining position and can simplify the set-up of the system. This determination is also simplified by the utilization of the synchronization signal which fires, in the preferred embodiment, once per revolution of the rotating head. For accuracy in a position measurement system, the angular velocity of the rotating head must not change during each revolution of the head.
The velocity of the rotating head is configurable through the use of, in the preferred embodiment, a field programmable gate array (“FPGA”). Such configurable speed control allows the transmitters to be differentiated by a receiver based on the transmitters' speed of rotation. The use of multiple transmitters, as is appreciated by those of ordinary skill in the art, enhances position detection. Other advantages are obtained through the use of programmable electronics (FPGAs, flash memory, etc). Not only can the desired speed be set by changing the clock to the phase locked loop which controls motor speed, but the overall gain of the control loop can be programmed to maximize performance at the velocity of interest.
C. Beam Type and Number
As described in the incorporated provisional and known in the art, position detection is also enhanced by using multiple beams and controlling the shape of those beams. These beams may be in the same rotating head assembly or in separate rotating head assemblies.
Two beams is the preferred number per rotating head assembly, however, more beams can be used. In particular, another embodiment uses four beams, two for short range and two for long range. The two short-range beams should have fan angles as large as possible. This allows the user to operate near the transmitters, such as in a room. For long-range, the user would normally be operating away from the transmitters. Therefore, in that circumstance the vertical extent of the beams could be reduced to maximize the range of the system. The beams are, preferably, of type III laser. However, the rotation of the beams reduces their intensity to the fixed observer such that they can be classified as type I lasers. Safety features are integrated into the device to prevent the powering of the lasers when the rotating head is not in motion. In the preferred embodiment at least two interlocks are utilized. The first depends on the phase lock loop. The lasers are turned off until the system is in phase-lock for at least 1024 phase-clock-cycles (approximately 32 revolutions). The second is monitoring the absolute speed using the once-per-rev index on the encoder. A tolerance is programmed into the system, currently 1-part-in-1000. When the velocity is outside that window the laser is not allowed to operate.
D. Beam Shape
The Transmitter allows flexibility in setting beams for the application. One advantage is that the beam shape can be modified for the application. The key is that the beam shape should correspond with correctly filling the de
Casteel Scott
Cuff Thomas
Hedges Thomas M.
Pratt Timothy
Slater Rick
Arc Second Inc.
Buczinski Stephen C.
Rader & Fishman & Grauer, PLLC
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