Abstract: In a workpiece production method a plurality of nominally similar workpieces are produced in a production process on one production machine. The order or time of production of some of the workpieces on the production machine is recorded. Some of the workpieces recorded are measured at two or more inspection stations. Dimensions or points of one workpiece are measured at one of the inspection stations, and corresponding dimensions or points of another of the workpieces are measured at another of the inspection stations. The results of the measurements of corresponding dimensions or points made at the two or more inspection stations are analysed together, taking account of the order or time of production of the workpieces. An output signal is produced based on the analysing of the results together. The output signal indicates performance of the production machine or of one or more of the inspection stations.

Abstract: In a workpiece production method a plurality of nominally similar workpieces are produced in a production process on one production machine. The order or time of production of some of the workpieces on the production machine is recorded. Some of the workpieces recorded are measured at two or more inspection stations. Dimensions or points of one workpiece are measured at one of the inspection stations, and corresponding dimensions or points of another of the workpieces are measured at another of the inspection stations. The results of the measurements of corresponding dimensions or points made at the two or more inspection stations are analysed together, taking account of the order or time of production of the workpieces. An output signal is produced based on the analysing of the results together. The output signal indicates performance of the production machine or of one or more of the inspection stations.

Abstract: A method of producing a workpiece which is successively loaded onto two or more machine tools and one or more machining operations are performed to produce one or more features of the workpiece on each machine tool. After the machining operations on both or all of the machine tools, the workpiece is passed to a common dimensional inspection station. At the common dimensional inspection station, dimensions of the features of the workpiece produced by the machining operations on the two or more machine tools are measured. Based on the results of measuring the dimensions of the features, two or more output signals are produced which respectively relate to the performance of the two or more machine tools which performed the machining operations. Each of the output signals is fed back to the machine tool which performed the respective operation, to adjust the production process of each corresponding machine tool.

Abstract: A manufacturing system includes: a coordinate positioning machine having a structure moveable within a working volume of the machine, a drive arrangement for moving the structure around the working volume, and a positioning arrangement for determining the position of the structure within the working volume with a first accuracy; and a metrology arrangement to which the machine is removably couplable, such that when the machine is coupled to the metrology arrangement, with the structure being moved by the drive arrangement, the metrology arrangement is able to measure the position of the structure with a second accuracy that is higher than the first accuracy.

Abstract: A method of producing a workpiece which is successively loaded onto two or more machine tools and one or more machining operations are performed to produce one or more features of the workpiece on each machine tool. After the machining operations on both or all of the machine tools, the workpiece is passed to a common dimensional inspection station. At the common dimensional inspection station, dimensions of the features of the workpiece produced by the machining operations on the two or more machine tools are measured. Based on the results of measuring the dimensions of the features, two or more output signals are produced which respectively relate to the performance of the two or more machine tools which performed the machining operations. Each of the output signals is fed back to the machine tool which performed the respective operation, to adjust the production process of each corresponding machine tool.

Abstract: In a workpiece production method a plurality of nominally similar workpieces are produced in a production process on one production machine. The order or time of production of some of the workpieces on the production machine is recorded. Some of the workpieces recorded are measured at two or more inspection stations. Dimensions or points of one workpiece are measured at one of the inspection stations, and corresponding dimensions or points of another of the workpieces are measured at another of the inspection stations. The results of the measurements of corresponding dimensions or points made at the two or more inspection stations are analysed together, taking account of the order or time of production of the workpieces. An output signal is produced based on the analysing of the results together. The output signal indicates performance of the production machine or of one or more of the inspection stations.

Abstract: A series of nominally identical production workpieces are measured on a workshop coordinate measuring apparatus. They are corrected using correction values generated by comparing coordinate values of a reference workpiece measured on the workshop apparatus with corresponding values derived from external measurements. To reduce the care and skill required, the external measurements are used to determine reference values of a geometric property of a feature of the reference workpiece, rather than coordinate values corresponding directly to those made on the workshop apparatus. Corresponding coordinate values are then generated from knowledge of the perfect form of the feature of the reference workpiece.

Abstract: Methods are described for measuring series of nominally identical production workpieces on a dimensional measuring apparatus such as a coordinate measuring machine. One master workpiece of the series is calibrated, to provide correction values which are used to build an error map of the measuring apparatus. This map is used to correct measurements not only of subsequent nominally identical workpieces of the same series, but also of multiple different subsequent series of different workpieces. Each subsequent series also has a master workpiece which is calibrated and used to further build the error map. As this process is repeated over time, the error map becomes more and more densely populated. In due course, it becomes possible to dispense with the use of a calibrated master workpiece, because measurements can be corrected using error values which already exist in the error map.

Abstract: A series of nominally identical production workpieces are measured on a workshop coordinate measuring apparatus. They are corrected using correction values generated by comparing coordinate values of a reference workpiece measured on the workshop apparatus with corresponding values derived from external measurements. To reduce the care and skill required, the external measurements are used to determine reference values of a geometric property of a feature of the reference workpiece, rather than coordinate values corresponding directly to those made on the workshop apparatus. Corresponding coordinate values are then generated from knowledge of the perfect form of the feature of the reference workpiece.

Abstract: A series of nominally identical production workpieces is measured on a measuring apparatus. To correct for temperature variations, one of the workpieces forms a master artifact, the dimensions of which are known. The artifact is measured on the measuring apparatus at two or more temperatures, producing two or more corresponding sets of measured dimensional values of the master artifact at the respective temperatures. One or more error maps, look-up tables, or functions are generated which relate the measured dimensional values of the artifact to the known dimensions of the artifact. The error map(s), look-up table(s) or function(s) are dependent on the respective temperatures at which the artifact was measured. Correction values derived from the error map(s), look-up table(s) or function(s) are used to correct the measurements of production workpieces in the series. These correction values are determined in dependence upon the temperature at which the workpiece measurements were obtained.

Abstract: An error correction method for coordinate positioning apparatus is described. The method comprises (i) taking a first data set comprising one or more first data values, each first data value describing a position on the surface of a first object, (ii) taking a second data set comprising one or more second data values, each second data value describing a position on the surface of the first object, and (iii) calculating an error map comprising one or more error values, each error value describing a positional difference between the surface as described by the first data set and the surface as described by the second data set. The surface normal of the first object is known at each position described by each first data value and step (iii) comprises calculating each error value by determining the positional difference substantially in the direction of the known surface normal.

Abstract: The position measuring system of a motion system such as a coordinate measuring machine is calibrated for static errors using one or more accelerometers. A displacement of the motion system is measured both using the position measuring system and by double integrating the outputs of the accelerometers. The displacement measurements using the accelerometers are less subject to static errors, or their static errors are repeatable and can be corrected. Comparing them with the measurements using the position measuring system therefore produces difference values, which can be used to build an error map or error function for correcting the static errors of the position measuring system.

Abstract: Methods are described for measuring series of nominally identical production workpieces on a dimensional measuring apparatus such as a coordinate measuring machine. One master workpiece of the series is calibrated, to provide correction values which are used to build an error map of the measuring apparatus. This map is used to correct measurements not only of subsequent nominally identical workpieces of the same series, but also of multiple different subsequent series of different workpieces. Each subsequent series also has a master workpiece which is calibrated and used to further build the error map. As this process is repeated over time, the error map becomes more and more densely populated. In due course, it becomes possible to dispense with the use of a calibrated master workpiece, because measurements can be corrected using error values which already exist in the error map.

Abstract: A method of operating coordinate positioning apparatus having a measurement probe includes taking a first part in a series of parts, at least a first reference geometrical property associated with one or more features of the first part being known and using the coordinate positioning apparatus to measure the one or more features of the first part and determining a first measured geometrical property corresponding to the first reference geometrical property. A first property correction value is then determined describing a difference between the first reference and the first measured geometrical properties. The coordinate positioning apparatus is then used to measure the one or more features of one or more further parts in the series of parts and, for each further part, a further measured geometrical property is determined corresponding to the first reference geometrical property. The first property correction value is then applied to each further measured geometrical property.

Abstract: A series of nominally identical production workpieces is measured on a measuring apparatus. To correct for temperature variations, one of the workpieces forms a master artefact, the dimensions of which are known. The artefact is measured on the measuring apparatus at two or more temperatures, producing two or more corresponding sets of measured dimensional values of the master artefact at the respective temperatures. One or more error maps, look-up tables, or functions are generated which relate the measured dimensional values of the artefact to the known dimensions of the artefact. The error map(s), look-up table(s) or function(s) are dependent on the respective temperatures at which the artefact was measured. Correction values derived from the error map(s), look-up table(s) or function(s) are used to correct the measurements of production workpieces in the series. These correction values are determined in dependence upon the temperature at which the workpiece measurements were obtained.

Abstract: Apparatus for a co-ordinate positioning machine is described that comprises an articulating probe head for supporting a measurement probe. The articulating probe head comprises at least one electric motor. Heating means are provided for generating heat in the articulating probe head. The heating means may be the motors or discrete heating elements. Temperature sensing means, such as one or more temperature sensors, is also provided for determining the temperature at the articulating probe head. The apparatus allows the temperature of the articulating probe head to be controlled.

Abstract: A method of operating coordinate positioning apparatus having a measurement probe includes taking a first part in a series of parts, at least a first reference geometrical property associated with one or more features of the first part being known and using the coordinate positioning apparatus to measure the one or more features of the first part and determining a first measured geometrical property corresponding to the first reference geometrical property. A first property correction value is then determined describing a difference between the first reference and the first measured geometrical properties. The coordinate positioning apparatus is then used to measure the one or more features of one or more further parts in the series of parts and, for each further part, a further measured geometrical property is determined corresponding to the first reference geometrical property. The first property correction value is then applied to each further measured geometrical property.

Abstract: An error correction method for coordinate positioning apparatus is described. The method comprises (i) taking a first data set comprising one or more first data values, each first data value describing a position on the surface of a first object, (ii) taking a second data set comprising one or more second data values, each second data value describing a position on the surface of the first object, and (iii) calculating an error map comprising one or more error values, each error value describing a positional difference between the surface as described by the first data set and the surface as described by the second data set. The surface normal of the first object is known at each position described by each first data value and step (iii) comprises calculating each error value by determining the positional difference substantially in the direction of the known surface normal.

Abstract: A method and apparatus for measuring a surface using a surface sensing device mounted on a scanning head on a member of a coordinate positioning apparatus. The coordinate positioning apparatus may be operated to produce relative movement between the scanning head and the surface profile and the scanning head includes a drive for producing rotational movement of the surface sensing probe about one or more axis. The coordinate positioning apparatus is driven to provide relative movement between the member and the surface profile in a circular path and the scanning head is driven to move the surface sensing device about said one or more axes, such that the surface sensing device maintains a nominally constant lead angle. The motion of the coordinate positioning apparatus and scanning head is synchronous.

Abstract: A surface sensing device for use in position determining apparatus has an elongate stylus (74) with a tip (82) for scanning the surface of a workpiece to be measured. Lateral displacements of the stylus tip are detected by a light beam which passes along the stylus from a light source (66) to a retroreflector (78). This reflects the beam back via a beamsplitter (70) to a position sensitive detector (76). The stylus is mounted for longitudinal displacement on a carriage (72). The longitudinal displacement is measured by another light beam projected by the beamsplitter (70) onto a second position sensitive detector (84).