Renishaw Plc

Renishaw Transducer Systems Limited

Seamus McFadden

Raymond J Chaney

Mark A Chapman

Andrew M Bailey

Marcus J Eales

Sergey Loukianov

In order to determine movements of two subjects, two or more signals of different phase are obtained which depend on the movement, and processed by locating constellation status of the signals in at least one co-ordinate axis system, it must have at least six separate segments rotationally displaced. Where there are two or more co-ordinate axis systems, each must have an axis radiating from an origin. The change in the constellation states is monitored using at least two processed data samples obtained by sampling the signals at a suitable clock rate. It is possible to derive a prediction of values of the signal and filter the signals in dependence on the prediction. The second co-ordinate axis system may be rotatable relative to the first co-ordinate axis system enabling the provision of a movable region of uncertainty.

Motion detection and analysis

A laser interferometer measuring system generates a series of digital output quadrature pulses corresponding to movement of a retroreflector 18. The output pulses are intended for receipt by a master counter containing an incremental count corresponding to displacement of the retroreflector 18. Errors present in the output pulses due to environmental or geometrical error sources in the interferometer may be compensated for by scaling the output pulses in accordance with a correction factor K. The output pulses are stored in a first counter 30, 130; a series of secondary pulses, being either the output pulses as scaled, or independently generated by a signal generator 200, are sent both to the master counter and a second counter 80, 180. A processor 50, 150 continually monitors the value of the second counter, and compares this with an actual value of displacement, equal to the product of the correction factor and the instantaneous value of the first counter. The frequency of secondary pulses transmitted to the master counter and the second counter is continually controlled by the processor in order to equalize the value of the second counter with the actual displacement value.

Real-time compensation system and method

A ball-bar 26 for calibrating machine tools and coordinate measuring machines comprise a unit 30 containing a displacement transducer 34 for measuring axial displacement of a precision ball 28. The ball 28 is pivotably located on the head or spindle 12 of the machine, which is driven in a circle about a ball 22 mounted on the bed or table 10 of the machine at the other end of the ball-bar in order to perform a calibration. The ball-bar has a modular construction, its various components such as the unit 30, extension bar 40, magnetic sockets 24,29, supporting device 14 and magnetic clamp 16 being connected together via M6 screw-threads, e.g. at 18,42,44. This enables the unit 30 to be connected to the various other components in a variety of configurations, e.g. for use as an electronic dial gauge.

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Bristol, United Kingdom

Seamus McFadden