Carl-zeiss-stiftung

Carl-zeiss-stiftung, Heidenheim/brenz

Helmut Muller

Eckhard Enderle

Roland Roth

Heinz Abramowsky

Werner Leitenberger

Peter Ebersbach

Rasmus Debitsch

For the correction of measurement errors, due to vibration, of coordinate measuring devices, the time course of the interfering vibrations is stored by means of sensors (a.sub.x, a.sub.y, a.sub.z) on a vibrating portion of the coordinate measuring device. The measured values of the sensors are adjusted with previously determined and stored correction parameters, which describe the natural frequency (.nu.) and the damping constants (.delta.) of the vibrations and also the amplitude and phase information of the characteristic modes (G.sub.r) of the vibrations contributing to the interfering vibrations. The measurement errors, due to vibration, of the coordinate measuring device at the instant of probing are then calculated from the time course of the corrected measurement values of the sensors (a.sub.x, a.sub.y, a.sub.z).

Method and device for the correction of measurement errors due to

The invention contemplates a technique to correct for measurement error which is attributable to gravitational sag of a probe head (6) mounted to a multiple-axis articulating head (2). To this end, a variable (b) is determined which describes the stiffness of the articulating head (2) and/or of a probe extension (5) mounted thereto, said variable being characteristic for the probe configuration in question and being entered into the memory of the computer of the coordinate-measuring machine. The sag B (.alpha., .beta.) which has differing values that depend on actual angular positions (.alpha., .beta.) is then calculated from these angular positions for each of the angular positions, and the calculated sag value is appropriately taken into account in computer-reporting of coordinate-measurement values made by the machine. Calibration of the articulating head in each of the various different angular positions is therefore unnecessary.

Method and apparatus to correct for gravitational sag in the articulated

The invention contemplates use of a suction bell to enhance the loading with which a guided machine part is gravitationally supported on its guide. In application to a machine in which the machine part is movably supported on air bearings, the suction bell applies a preload force of magnitude to optimize the stiffness of air-bearing action and to maintain an air gap of uniform capillary thickness, free of mechanical contact between the machine part and its supporting surface.

Device for preloading a guided machine part

The invention is directed to a protective arrangement for a longitudinally extendible machine component such as a measuring arm of a machine such as a coordinate measuring apparatus. The protective arrangement includes a light barrier unit having a response sensitivity and including a light source for directing a light beam parallel to the axis of the machine component as well as first and second detectors for receiving first and second portions of the light beams and for supplying first and second signals indicative of the intensities of the portions of the light beam. The light source and the detectors are mounted on the machine component so that the length of the light beam between the source and the detectors and the respective light intensities received by the detectors change in correspondence to the distances as the machine component is extended or retracted. A structure shades the light beam in response to a contact engagement of the structure with an object or person. A comparator circuit compares the signal of the detectors and remains nonconductive so long as the light intensities uniformly increase or decrease with changes in the above-mentioned distances. The comparator circuit provides an output signal for bringing the machine component to standstill in response to uneven changes in the light intensities received by the detectors relative to each other when the beam becomes shaded. In this way, a control unit of the machine can, for example, initiate an emergency stoppage of the machine component thereby preventing injury to personnel or damage.

Protective arrangement for a longitudinally extendible machine component

The invention is directed to a protective arrangement for a longitudinally extendible machine component such as the measuring arm of a machine such as a coordinate measuring apparatus. The protective arrangement includes a bellows which at least partially surrounds the machine component and has a plurality of structural parts at least one of which is deflectable relative to the longitudinal axis of the machine component in response to a contact of the bellows with an object or person. Each of the structural parts has a cutout formed therein and the parts are disposed in the bellows so as to cause the cutouts to be mutually aligned in the undeflected condition of the bellows. A light barrier directs a light beam through the cutouts which becomes at least partially shaded in response to a deflection of the one structural part. The light barrier generates a signal in response to the shading and this signal is supplied to a protective circuit in the control unit of the machine which can, for example, initiate an emergency stoppage of the machine component thereby preventing damage.

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Schwabisch-Gmund, Germany

Helmut Muller