Renishaw Plc

Ferranti Plc

Renishaw Metrology Limited

Mtem Ltd

Other

Pgs Geophysical As

The University of Edinburgh

Ferranti International Plc

Reinshaw Plc

Erenishaw Plc

David Allan Wright

David R McMurtry

Alexander Tennant Sutherland

Antoni Marjan Ziolkowski

Bruce Alan Hobbs

Kevyn Barry Jonas

Stephen E Lummes

Alan James Holloway

Brian E Pitches

Kenneth Cheng-Hoe Nai

Anton Ziolkowski

Graham Dawes

A method for determining resistivity distribution of formations below a bottom of a body of water from transient electromagnetic signals acquired by imparting a transient electromagnetic field into the water and detecting an electromagnetic response thereto at a plurality of spaced apart positions from a place of the imparting includes simulating an air wave response at each of the plurality of spaced apart positions. The simulated air wave response is subtracted from the detected response to produce a subsurface impulse response at each of the plurality of positions. The subsurface impulse responses are used to determine the resistivity distribution.

Method for estimating and removing air wave response in marine electromagnetic surveying

A method for mapping sub-surface resistivity contrasts comprising making multi-channel transient electromagnetic (MTEM) measurements using at least one electric source with grounded input current electrodes or one magnetic source with current in a wire loop or multi loop and at least one electric field or magnetic field receiver, measuring the resultant earth response simultaneously at each receiver using a known recording system, measuring the system response by measuring directly the current in the wire at the source using effectively the same recording system, using the measured system response to recover the impulse response of the earth from each measured earth response, and creating from such impulse responses a sub-surface representation of resistivity contrasts.

True amplitude transient electromagnetic system response measurement

A method for measuring the electromagnetic response of formations below the bottom of a body of water includes positioning at least one electromagnetic transmitter and at least one electromagnetic receiver in the body of water each at a selected depth below the water surface. A transient electric current is passed through the at least one transmitter. An electromagnetic signal is detected at the at least one electromagnetic receiver. The depths are selected so that substantially all electromagnetic response to the current passed through the transmitter from the air above the body of water in the detected electromagnetic signal occurs before the beginning of a response originating in the formations below the water bottom.

Method for attenuating air wave response in marine electromagnetic surveying

The invention relates to a method of mapping subsurface resistivity contrasts by making multichannel transient electromagnetic (MTEM) measurements on or near the earth's surface using at least one source, receiving means for measuring the system response and at least one receiver for measuring the resultant earth response. All signals from the or each source-receiver pair are processed to recover the corresponding electromagnetic impulse response of the earth and such impulse responses, or any transformation of such impulse responses, are displayed to create a subsurface representation of resistivity contrasts. The invention enables subsurface fluid deposits to be located and identified and the movement of such fluids to be monitored.

Detection of subsurface resistivity contrasts with application to location of fluids

Accelerations of a probe or probe head due to vibrations of a machine during a measuring operation are measured using accelerometers placed in the probe or probe head. The acceleration signals are double integrated to determine the corresponding displacements of the probe or probe head and these are added to the readings of displacement of the machine taken from the machine scales using a data fusion algorithm to correct the scale readings for the vibration of the probe. Both linear and angular accelerations of the probe can be corrected in this way.

Method of and apparatus for correction of coordinate measurement errors due to vibrations in coordinate measuring machines (cmms)

A surface sensing device includes an articulating head adapted for attachment to the spindle of a measuring machine and having two relatively rotatable parts capable of rotation about two mutually perpendicular axes. The device additionally includes a stylus assembly having a relatively stiff hollow stylus carrier, and a relatively flexible hollow stylus. An optical transducer system is provided within the stylus assembly and comprises a fixed light source which directs a beam of light towards a stylus tip, and a retro-reflective component at the tip which reflects the beam back to a fixed detector. The arrangement is such that lateral displacement of the stylus tip when the tip is in contact with a surface can be measured directly.

Surface sensing device with optical sensor

A method of calibrating a scanning system comprising a machine and a measuring probe, includes the steps of error mapping the system statically and qualifying the stylus tip so that the system will provide accurate measurements, determining the positions of a number of datum points on the surface of an artefact with the probe stylus in contact with the workpiece and at zero deflection normal to the surface, scanning the surface through the datum points at a nominal stylus deflection and at the maximum speed which provides repeatable position measurements to make a second determination of the positions of the datum points, determining the errors attributable to the scanning process by subtracting the positions obtained in the first and second determinations, and storing the error values for correction of subsequent measurements of similar artefacts.

Method of calibrating a scanning system

An analogue probe having a stylus with a spherical tip of radius (r) is calibrated using a sphere of known radius (R) mounted on a machine. The stylus tip is driven into the sphere from a plurality of directions (at least 9), each nominally normal to the sphere surface, until the stylus has deflected a predetermined amount. The machine movement is then reversed, and probe (a,b,c) deflection outputs are recorded simultaneously with machine (X,Y,Z) axis positions until the stylus tip leaves the surface. The readings are extrapolated to obtain the (X,Y,Z) readings when the probe radial deflection is zero. The value of (R&plus;r) is determined from these readings along with the position of the sphere center giving a value with zero probe errors. Values of (R&plus;r) are also determined using a pre-selected radial deflection for each of the directions, by converting probe (a,b,c) outputs at that deflection to incremental machine (X,Y,Z) axis values using a trial probe transformation matrix. The differences in (R&plus;r) values from the value obtained by extrapolation are noted as an error in each case, and the trial probe matrix is then optimized until the errors are minimized using the transformation obtained by the calibration, the probe can be error mapped.

Calibrations of an analogue probe and error mapping

Readhead for an opto-electronic rotary encoder

A machine is disclosed having novel air bearings for supporting one machine part for translational movement on another part in a first direction X. Each bearing takes the form of a track (5A,14,16) on one of the parts providing concave part-cylindrical bearing surfaces (5A,14A,16A) and pads 25 on the other part providing confronting convex part-cylindrical bearing surfaces 25A. The arc lengths of the part-cylindrical bearing surfaces are such as to provide restraint against relative movements between the machine parts in at least one sense of both of the two directions (Y,Z) orthogonal to the direction (X) of the translational movement. The advantages are relative cheapness of manufacture compared to vee-bearings and a capability of the bearings to self-align under load.

Bearings

Measuring probe

Apparatus with a multi-axis mechanism to perform, say, measurements or tests, has at least one pair of temperature detectors individually for each of selected members of the mechanism, each pair of temperature detectors being arranged to sense temperature differences transversely across the associated member. The required positions of the temperature detectors are predetermined from a preliminary examination of the mechanism, so that the extent and direction of each predetermined aspect of thermal distortion within the mechanism, can be computed from simultaneously detected transverse temperature differences, employing algorithms devised as a result of the preliminary examination of the mechanism. Compensation for corresponding selected errors in the measurements or tests can be calculated from the computed extent and direction of each of the predetermined aspects of thermal distortion within the mechanism.

Error determination for multi-axis apparatus due to thermal distortion

Apparatus for determining the position of a point movable throughout a measuring volume relative to a set of reference axes includes a probe member (10) having a probe tip (11) defining the position of the movable point. The measuring probe (10) also has first and second reference points (12, 13) spaced apart from one another and having a fixed known spatial relationship with one another and with the probe tip (11). Means (16) are provided for moving the probe member (10) so that the probe tip may be positioned at any desired point within the measuring volume. At least three distance measuring equipments (15) are provided, located outside the measuring volume at fixed known positions relative to the set of reference axes and each operable to determine the distance between it and each of the reference points (12, 13) on the probe member (10). Calculating means (19) are provided to calculate from said distance measurements the position of the probe tip (11). The distance measuring equipments (15) may be laser rangefinders, with reflectors mounted on the probe member (10) at the reference points (12, 13).

Three-dimensional position measuring apparatus

Measuring apparatus for determining the position of a point in a measuring volume relative to a datum point at which three mutually perpendicular axes intersect, includes a probe member supported for movement within that volume. Errors due to rotations about the various axes are corrected by providing additional transducers on each axis, there being (n+1) transducers where n is the number of rotations for which correction is required. The embodiments described have three X-axis transducers X.sub.1, X.sub.2 and X.sub.3 and three Y-axis transducers Y.sub.1, Y.sub.2 and Y.sub.3 which, with the appropriate circuitry correct for pitch and yaw errors about the two axes. For the Z-axis only two transducers, Z.sub.1 and Z.sub.2, are required. The circuit means combines the various transducer outputs to derive corrected values of the three co-ordinates.

Growing community of inventors

Edinburgh, United Kingdom

David Allan Wright