Radiant energy – Photocells; circuits and apparatus – With circuit for evaluating a web – strand – strip – or sheet
Patent
1995-09-05
1998-02-03
Westin, Edward P.
Radiant energy
Photocells; circuits and apparatus
With circuit for evaluating a web, strand, strip, or sheet
25055942, 25055939, G01N 2101
Patent
active
057147620
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to the determination of the surface properties of an object, in particular the remote, contactless determination of one or more of surface orientation, distance, displacement, shape or the presence of surface discontinuities such as walls, corners and holes.
2. Discussion of Prior Art
In many industrial applications, such as robotic welding and laser materials processing, it is necessary to maintain the processing head or heat source at a constant standoff and with constant orientation relative to the surface of the object to be treated. This is often achieved by programming the robotic device by human teaching to follow the surface contour. However, in situations requiring remote handling, eg servicing, repairing or decommissioning of a nuclear materials processing plant, it is necessary for the surface contour to be detected by the robot with sensors. This is difficult to achieve particularly when the object is irregular with corners, sharp bends and vertical walls. The previous techniques for detecting the surface contour profile have been by tactile probes connected to a position sensor such as a LVDT (Linear Variable Differential Transformer) or linear resistance potentiometer, or non-contact proximity switches or sensors such as capacitive (for metal surfaces only), inductive (for metal surfaces only) and photoelectric sensors. Recently diode laser triangulation has been used with PSD (position sensitive devices which are usually linear photoelectric sensor arrays). All these devices require either direct contact or a close proximity to the surface. None of these devices give the information on surface orientation. In fact the accuracy of most of the devices is affected by the surface orientation and materials properties. With robotic laser materials processing, for example, orientation of the beam with the surface can affect the beam absorption. Thus the consistency of the processing quality cannot be maintained without knowing this information. Also, the control of robotic movement with short distance proximity sensor feedback could be risky in the cases of sharp corners, holes and walls.
A number of arrangements are described in the prior art which detect changes in the properties of a beam of optical radiation caused by reflection or scattering from the surface of an object to be investigated. The optical images formed on the object have been either one dimensional line images or simple two dimensional ring images and consequently it would not be possible to obtain suitable control information from such images. The effect of external lighting has not been considered in these prior art arrangements.
In particular, GB 2241061A describes a technique wherein one or more beams are projected onto a rotating object. The beam is essentially one or more one-dimensional stripes and information such as surface orientation at a particular region of the surface is not obtained and cannot be obtained (without relative motion and repeated scanning of the beam).
GB 2104652A discloses a method whereby a butt or seam on an object can be recognised during welding. Light in the form of a parallel line shaped grid is reflected from the object. There are no intersections between individual lines and the light structure is not therefore a truly two-dimensional and cannot be used to obtain orientation of the surface at the point of incidence. Also, the workpiece shape recognition resolution depends on the spacing of the projected grid lines. This system is suitable for an area shape recognition or location of features such as seams or butts rather than for on-line three dimensional tracking with orientation control. Also, possible influence of arc light on the sensing system may prevent the application of the device for real time applications. The system cannot provide multiple information such as x-y orientation, position and neighbourhood geometry at the same time for a spot on the workpiece surface.
WO 9009560 describes an arrangemen
REFERENCES:
patent: 4411528 (1983-10-01), Newcomb et al.
patent: 4674875 (1987-06-01), Koizumi
patent: 4731855 (1988-03-01), Suda et al.
patent: 4842411 (1989-06-01), Wood
patent: 5150254 (1992-09-01), Saitou
patent: 5426506 (1995-06-01), Ellingson et al.
patent: 5471298 (1995-11-01), Moriya
Li Lin
Modern Peter Julian
Steen William Maxwell
British Nuclear Fuels PLC
Pyo Kevin
Westin Edward P.
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