Abstract: A method of calibrating a measurement probe (10) mounted on a machine is described. The measurement probe (10) has a stylus (14) with a workpiece contacting tip (16). The method comprises determining a probe calibration matrix that relates the probe outputs (a,b,c) to the machine coordinate system (x,y,z.). The method comprising the steps of scanning a calibration artefact (18) using a first probe deflection (d1) to obtain first machine data and using a second probe deflection (d2) to obtain second machine data. The first and second machine data are used to obtain a pure probe calibration matrix in which any machine errors are substantially omitted. Advantageously, the method determines the pure probe matrix numerically based on the assumption that the difference between the first and second machine position data is known.

Abstract: A method is described for calibrating apparatus including a measurement probe mounted on a machine, such as a machine tool. The machine is arranged to capture machine position data indicative of the position of the measurement probe and the measurement probe is arranged to capture probe data indicative of the position of a surface relative to the measurement probe. The measurement probe may be an analogue or scanning probe having a deflectable stylus. The first step of the method involves moving the measurement probe at a known speed relative to an artefact whilst capturing probe data and machine position data. In particular, the measurement probe is moved along a path that enables probe data to be captured that is indicative of the position of two or more points on the surface of the artefact relative to the measurement probe.

Abstract: A method is described for calibrating apparatus comprising a measurement probe (4) mounted on a machine, such as a machine tool. The machine is arranged to capture machine position data (x,y,z;70;80) indicative of the position of the measurement probe and the measurement probe is arranged to capture probe data (a,b,c;72;82) indicative of the position of a surface relative to the measurement probe (4). The measurement probe (4) may be an analogue or scanning probe having a deflectable stylus (14). The first step of the method involves moving the measurement probe (4) at a known speed relative to an artefact (30;40,42) whilst capturing probe data (a,b,c;72;82) and machine position data (x,y,z;70;80). In particular, the measurement probe (4) is moved along a path that enables probe data (a,b,c;72;82) to be captured that is indicative of the position of two or more points on the surface of the artefact relative to the measurement probe (4).

Abstract: A method of calibrating a measurement probe (10) mounted on a machine is described. The measurement probe (10) has a stylus (14) with a workpiece contacting tip (16). The method comprises determining a probe calibration matrix that relates the probe outputs (a,b,c) to the machine coordinate system (x,y,z.). The method comprising the steps of scanning a calibration artefact (18) using a first probe deflection (d1) to obtain first machine data and using a second probe deflection (d2) to obtain second machine data. The first and second machine data are used to obtain a pure probe calibration matrix in which any machine errors are substantially omitted. Advantageously, the method determines the pure probe matrix numerically based on the assumption that the difference between the first and second machine position data is known.

Abstract: A method of calibrating a probe mounted on a machine in which the probe has a probe calibration matrix which relates the probe outputs in three orthogonal axes to the machine's X, Y and Z coordinate system. A datum ball mounted on the machine is bi-directionally scanned by the probe in one or more planes. For each plane, the mean direction of two approximate probe vectors in the plane is rotated about an axis orthogonal to that plane until the apparent material condition from the scan in each direction is the same. This process may be iterative. The mean values of the directions of the probe vectors for each plane are rotated, thus forming a corrected probe calibration matrix. The datum ball is preferably bi-directionally scanned in three orthogonal planes.

Abstract: A method of measuring an artefact 5 using a machine 2 on which a measuring probe 6 is mounted. The probe is brought into contact with the artefact and movement continued for a limited distance to deflect the stylus 7. The machine and probe outputs are recorded whilst the probe is free and when the stylus is deflected. A model of the probe and CMM outputs during both contact and non-contact between the probe and artefact is fitted to the data to allow the contact position when the stylus contacts the artefact with zero force to be determined. The probe outputs may be fitted to the model individually to determine a single contact position. By using data during movement of the probe towards and away from the artefact, errors due to time delays may be corrected.

Abstract: A method of calibrating a probe mounted on a machine in which the probe has a probe calibration matrix which relates the probe outputs in three orthogonal axes to the machine's X, Y and Z coordinate system. A datum ball mounted on the machine is bi-directionally scanned by the probe in one or more planes. For each plane, the mean direction of two approximate probe vectors in the plane is rotated about an axis orthogonal to that plane until the apparent material condition from the scan in each direction is the same. This process may be iterative. The mean values of the directions of the probe vectors for each plane are rotated, thus forming a corrected probe calibration matrix. The datum ball is preferably bi-directionally scanned in three orthogonal planes.

Abstract: A method of measuring an artefact 5 using a machine 2 on which a measuring probe 6 is mounted. The probe is brought into contact with the artefact and movement continued for a limited distance to deflect the stylus 7. The machine and probe outputs are recorded whilst the probe is free and when the stylus is deflected. A model of the probe and CMM outputs during both contact and non-contact between the probe and artefact is fitted to the data to allow the contact position when the stylus contacts the artefact with zero force to be determined. The probe outputs may be fitted to the model individually to determine a single contact position. By using data during movement of the probe towards and away from the artefact, errors due to time delays may be corrected.