Optics: measuring and testing – Angle measuring or angular axial alignment – Apex of angle at observing or detecting station
Patent
1984-10-12
1987-05-19
Buczinski, Stephen C.
Optics: measuring and testing
Angle measuring or angular axial alignment
Apex of angle at observing or detecting station
33304, 33313, 356 1, G01B 1126, G01C 100, E21B 47022
Patent
active
046663002
DESCRIPTION:
BRIEF SUMMARY
This invention concerns position measuring method and apparatus, particularly, but not exclusively, for determining the position of the end of an underground passage, such as the end of a tunnel, especially one which is too small or too dangerous for human access.
One conventional method of surveying constructions such as a tunnel involves measuring distance to a fixed point within the tunnel and the angle that point makes with respect to a known baseline. If the tunnel is curved, the location of the end of the tunnel may have to be determined by establishing a series of intermediate sites, each visible from its nearest neighbour and each surveyed from its neighbour. However, if the tunnel is of very small diameter, and/or has a dangerous environment, e.g. biotoxic, human access is excluded and this method is not feasible.
In remotely piloted boring of narrow tunnels or pipes it is important to establish accurately the location of the end of the tunnel. In general, free access to the tunnel is not available and the presence of inhomogeneities or obstructions in the ground render wave propagation source and detector systems unreliable.
Our own GB-PS No. 1,513,380 describes an invention which can be miniaturised and utilised as a tunnel guidance system for earth-working, tunnel-boring etc. machinery, and which can be used to determine the position of a target, provided that the target and a laser beam directed towards the target are in a straight line. Remotely controllable and monitorable television scanning/monitoring systems utilising beams and targets are also known but they are not only complicated and expensive but are also unable to operate along curved paths.
According to one aspect of the invention there is provided apparatus for determining the position of an unknown fixed location e.g. the end of an underground passage inaccessible to human beings, comprising a plurality of measuring stations disposed at a known distance from each other along a path towards said locations, said stations being linked together so as to form a communication chain disposed along said path, means at each station (except optionally, the first one) for measuring the angle of inclination in at least one plane of the station immediately ahead of it, means for transmitting the measurement results to the first station or other accessibly located base station and means for calculating the position of said fixed location from said measurement results.
Preferably the measuring means comprises an optical goniometer; advantageously, each station may incorporate at least one illuminated area directed towards the succeeding station and at least one photodetector directed towards the preceding station. However, other transducers and data transceivers may also be used.
Preferably, the goniometer is effective to measure angles of inclination with means for maintaining its orientation relative to a reference plane or axis.
The goniometer may include optical element(s) effective to produce a band or line image of the light source on the photodetector(s)--which may be arrays of photodetecting elements--to render the measurement insensitive to the position of said source in a given plane.
The term `light` is used broadly as including not only visible light but also infrared and ultraviolet light; the actual wavelength of the radiation is not material, provided of course that the detector is responsive or sensitive to that wavelength.
Means may be provided for selectively and sequentially energising and de-energising the light sources and/or the detectors of the chain so as to avoid the possibility of a given detector receiving light from than one upstream station.
In a preferred embodiment, a servo-system incorporating a level sensor is provided to maintain the detector horizontal.
Each station preferably transmits raw data, via cables, to a base station for processing, and storing displaying, recording etc.
The stations may each process the measurement results (hereafter: data) but preferably the data is transmitted in a `raw` or unproce
REFERENCES:
patent: 3494699 (1970-02-01), Globe
patent: 3751169 (1973-08-01), Fornerod
patent: 4068208 (1978-01-01), Rice et al.
patent: 4231111 (1980-10-01), Neeley
Kernthaler John E.
Zollman Peter M.
Buczinski Stephen C.
Zed Instruments, Ltd.
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