Abstract: A hexapod machine comprises a fixed structure (10,11) and a movable structure (14,15). Six extensible legs (18) are connected between the fixed and movable structures, and their lengths determine the relative position and orientation of the structures. The lengths of the legs are measured by respective laser interferometers (60,62). To increase the accuracy of the measurement, a retroreflector (62) of the interferometer is directly mounted to and fast with one of the structures (14,15).

Abstract: A capacitance probe is used by a coordinate measuring machine or machine tool to determine distances from the probe to the workpiece surface at various points over the surface. The probe is calibrated by moving it along a line, which is skewed to the surface. During this movement, a plurality of values of the capacitance and the corresponding values of the actual distance moved along the line are recorded. A datum value for the movement along the skewed line is also determined, which corresponds to a position at which the probe would touch the surface. The probe is calibrated without needing separate independent measurements of the distance from the probe to the surface. The workpiece surface is scanned using the thus-calibrate probe, in which different calibration values are used at different points on the surface, in order to account for the local shape of the surface.

Abstract: A combined interferometer and refractometer includes two interferometers each of which uses a light beam produced from a common source which are split into measuring component beams and reference component beams. The measuring component beams are directed along parallel paths to an object and are reflected back from reflecting surfaces on the object which is so positioned as to produce a fixed path length difference between the beams. The reflected beams are re-combined with the reference component beams to produce output beams which pass to a detector system which derives an output signal from each. Changes in refractive index are determined from any difference in the two output signals, and the distance moved by the object is determined from any change in either one of the output signals or by summing them and dividing by two. Methods are described whereby the measurements of refractive index or of distance can be made absolute.

Abstract: A touch probe includes a stylus module (54) and a sensing module (52) to which the stylus module is releasably securable by a magnetic coupling. The sensing module comprises a strain sensitive load cell on which the stylus module is supported, and which senses strain in the stylus on contact with a surface. The stylus module provides for overtravel of the probe; a stylus-supporting member being biased into a kinematic rest position with respect to the casing of the stylus module. The biasing force in the stylus module is chosen with regard to the length and configuration of stylus. This modular system enables automated stylus changing without the need to adjust the biasing force on the stylus-supporting member when different lengths of styli are employed.

Abstract: A touch trigger probe for a coordinate measuring machine or machine tool has a stylus (14), which is biased into a rest position. The stylus has two independent supports, provided within a housing (10). In the embodiment of FIG. 1, the first support comprises a skirt (18) of a stylus holder (12), which is axially constrained on a surface (20) of the housing (10). The second support comprises a kinematic arrangement of cylinders (34) and balls (36), together with a planar spring (30), which together provide lateral constraint. The first support is biased by a much lighter force than the second support, so that its friction is very low. This reduces the lobing and hysteresis of the stylus movement, and thereby increases the accuracy of the probe.

Abstract: An automatic pallet handling system for a machine tool is described in which the pallets are formed as lightweight cassettes (10) which can be mounted by means of shaped locating features on the external periphery of a receiving device (4) mounted, for example, for rotation with a horizontal indexing spindle (2) in a vertical spindle CNC machine. A portable cassette-loading system (15) which consists of a chain conveyor (17) having links (18) pivotably connected side-by-side and formed from lightweight extrusions is positionable adjacent the machine or removable to a loading station. The extruded links form features for engaging the same cassette-locating features on the cassettes and a transfer mechanism (50) slides the cassettes from the loading conveyor to the periphery of the receiving device.

Abstract: An arm 12 for holding a tool-setting probe 14 in a machine tool is rotatable between an operative position and an inoperative position. The operative position is defined by elements 48,52 which form a stop against further rotary motion beyond the operative position. These elements 48,52 are arranged as a kinematic support, so that the operative position is defined in a precisely repeatable manner. Springs 40 urge the elements 48,52 together. When the arm is in the operative position, these springs are stretched by a repeatable amount, so that they provide a repeatable force, in order to increase the precision of the operative position.

Abstract: A touch trigger probe incorporates piezoelectric sensors 50, whose outputs are processed by an interface circuit. The interface circuit discriminates between signals generated from the piezoelectric sensors 50 as a result of machine vibration and those generated as a result of a genuine measurement event, by the use of a timing circuit 90. The timing circuit 90 compares the time intervals (t.sub.1 -t.sub.2);(t.sub.2 -t.sub.3) between attainment of first 1.sub.1 and second 1.sub.2, and second 1.sub.2 and third 1.sub.3 output signal levels from the sensor 50, and upon the basis of this comparison validates (or rejects) measurements made with the probe. Additionally, the interface determines whether measurements made with the probe are taken upon the basis of outputs generated by the sensors 50 due to a shock wave in the stylus 24 of the probe, or as a result of strain in the stylus 24; as an alternative, measurements may be made only on the basis of strain.

Abstract: A magazine has a plurality of storage ports 400 each of which retains a stylus module 314 for use in measuring workpiece dimensions on a coordinate measuring machine. Each storage port 400 is configured as a pair of jaws provided by docking inserts 414. A permanent magnet 418 is mounted on each docking insert 414. The lower casing of the stylus module 314 is urged against the inwardly facing edges 416 of the docking inserts 414 by the magnetic attraction force due the magnets 418. The stylus module 314 is engaged with a retaining module (on the quill of the machine) by moving the retaining module in a downward sense to engage the stylus module 314; further downward movement disengages the stylus module 314 from the storage port 400, thus enabling engagement of such a stylus module and removal of the module from the storage port in a single continuous movement.

Abstract: A measuring machine includes a table, a base and a metrology frame that supports carriages for moving a probe around the working volume of the machine. The metrology frame is fabricated into a lightweight but torsionally rigid structure. The base that supports the metrology frame on the table is rigidly connected to the metrology frame but is kinematically located on the table by supports. The table and the base can also be made as relatively lightweight structures but distortions of the table due to heavy workpieces are not transmitted to the metrology frame. The construction of the machine also enables it to be easily dismantled and packed for transportation.

Abstract: An analogue probe has a fixed structure and a stylus supporting member connected to the fixed structure by three serially mounted pairs of leaf springs interconnected by first and second intermediate members. The stylus supporting member supports an elongate stem upon which a cube, which supports three scales, is mounted. Readheads are mounted on the fixed structure, in register with the scales, to transduce movement of the stylus supporting member in three substantially orthogonal directions. The alignment of the scales about the yaw axis (extending in a direction perpendicular to the plane of the scale) determines the alignment of the measuring axes of the probe, while the straightness of the lines of the scales determines the straightness of the axes.

Abstract: 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.

Abstract: A touch trigger probe for a coordinate measuring machine or machine tool has a stylus (14), which is biased into a rest position. The stylus has two independent supports, provided within a housing (10). In the embodiment of FIG. 1, the first support comprises a skirt (18) of a stylus holder (12), which is axially constrained on a surface (20) of the housing (10). The second support comprises a kinematic arrangement of cylinders (34) and balls (36), together with a planar spring (30), which together provide lateral constraint. The first support is biased by a much lighter force than the second support, so that its friction is very low. This reduces the lobing and hysteresis of the stylus movement, and thereby increases the accuracy of the probe.

Abstract: A measuring probe comprises a stylus-carrying member on which a stylus is magnetically retained. The carrying member is supported on a flat diaphragm spring for tilting movement relative to an intermediate member. The intermediate member is supported on two further diaphragms for linear movement relative to a housing. The spring rates of diaphragm and further diaphragms are chosen to give the probe the desired relative force/displacement characteristics in X,Y and Z.

Abstract: A touch trigger probe includes a hybrid integrated circuit (58). On this circuit are provided both kinematic support elements (28) for supporting a deflectable stylus (14) in a precise rest position, and sensing elements (40) for detecting contact between the stylus (14) and a workpiece. Embodiments are also disclosed in which the kinematic support elements are provided on a silicon chip, e.g. by micro-machining.

Abstract: A touch probe for use on a coordinate positioning machine includes a stylus module and a sensing module securable to a movable arm of the positioning machine for releasably supporting the stylus module. The sensing module can include a sensor for detecting contact between the stylus and a surface and/or for detecting displacement of the stylus module relative to the movable arm. The stylus includes a support structure, releasably supported by the stylus module, and a stylus-supporting member for supporting the stylus, with the stylus-supporting member being biased into a rest position with respect to the support structure. The stylus-supporting member is displaceable from the rest position and relative to the support structure when a deflection force acts on the stylus, and returns to the rest position when the deflecting force is removed.

Abstract: A coordinate positioning machine is equipped with either an optical probe or a contact measuring probe. Movement of the head of the machine to enable the probe to scan an unknown surface is controlled by predicting the position of a subsequent point to which the head of the machine is to be driven upon the basis of three most recently measured points, P.sub.1, P.sub.2, P.sub.3. The prediction of the subsequent point P.sub.4 is performed by machine control in real time.

Abstract: A magazine has a plurality of storage ports 400 each of which retains a stylus module 314 for use in measuring workpiece dimensions on a coordinate measuring machine. Each storage port 400 is configured as a pair of jaws provided by docking inserts 414. A permanent magnet 418 is mounted on each docking insert 414. The lower casing of the stylus module 314 is urged against the inwardly facing edges 416 of the docking inserts 414 by the magnetic attraction force due the magnets 418. The stylus module 314 is engaged with a retaining module (on the quill of the machine) by moving the retaining module in a downward sense to engage the stylus module 314; further downward movement disengages the stylus module 314 from the storage port 400, thus enabling engagement of such a stylus module and removal of the module from the storage port in a single continuous movement.

Abstract: A touch probe for use on a coordinate positioning machine includes a stylus module and a sensing module securable to a movable arm of the positioning machine for releasably supporting the stylus module. The sensing module can include a sensor for detecting contact between the stylus and a surface and/or for detecting displacement of the stylus module relative to the movable arm. The stylus includes a support structure, releasably supported by the stylus module, and a stylus-supporting member for supporting the stylus, with the stylus-supporting member being biased into a rest position with respect to the support structure. The stylus-supporting member is displaceable from the rest position and relative to the support structure when a deflection force acts on the stylus, and returns to the rest position when the deflecting force is removed.

Abstract: A capacitance sensing probe is disclosed for taking measurements of features on a workpiece surface. The probe has two electrodes (E.sub.1, E.sub.2) spaced apart in the direction of movement of the probe with the electrodes being disposed in an attitude normal to the surface. Only the edge of the electrodes are exposed to the surface and an electric circuit (EC) is provided for determining the effect of the surface on the fringe field capacitance between the electrodes. Guard electrodes are used to reduce the stray capacitance being measured. Various embodiments are shown with different numbers and arrangements of electrodes.