The Boeing Company

Thomas A Greenwood

Thomas W Pastusak

Large machines, especially those having working envelopes in excess of fifteen feet, exhibit unacceptable errors because of thermal expansion and mechanical misalignments between the axes. The errors have traditionally been minimized by enclosing the machine in a thermal enclosure, by careful calibration, or by mounting a laser interferometer on each axis. These solutions are costly, may require frequent recalibration, and do not correct for small rotations of one axis relative to another axis due to wear etc. The present invention uses an interferometric laser tracker or a comparable 3D position sensor to measure the position of a retroreflector attached to the end effector, e.g. a machine head when the machine comes to rest. A computer compares the measured position to the desired position according to the machine media, and adds the appropriate correction with trickle feed media statements to move the machine to the correct position prior to further machining.

Software for improving the accuracy of machines

Method for improving the accuracy of machines

A steerable retroreflective system is disclosed that includes a retroreflector that reflects at least some light incident upon the retroreflector, while permitting at least some of the incident light to leak therethrough. The steerable retroreflective system also includes an optical detector that detects leakage light that passes through the retroreflector. The steerable retroreflective system further includes means for controllably steering the retroreflector in response to the leakage light detected by the optical detector, such as to track the incident light. The method of controllably steering the retroreflector is also disclosed. The steerable retroreflective system and method therefore provides a retroreflective target with a much wider acceptance angle than conventional retroreflective targets. As a result, the retroreflective target can continue to be illuminated by a laser tracker and can continue to provide information indicative of the position of the retroreflective target as a machine tool on which the retroreflective target is mounted is moved during machining operations.

Steerable retroreflective system and method

A machine system having optical endpoint control and an associated method for monitoring the position of a machine are provided which includes at least one steerable retroreflective system that defines a relatively large effective acceptance angle, typically exceeding 320&deg;. In particular, the machine system includes a machine capable of movement in at least one direction and a steerable retroreflective system mounted upon the machine, such as upon the end effector of the machine, for movement therewith. The machine system also includes at least one light source for illuminating the retroreflector such that the position of at least a portion of the machine is determinable based upon reflections from the retroreflector. As such, the machine system can make any necessary corrections in the computer control of the machine to accommodate for differences between the anticipated position of the machine and the actual position of the machine.

Machine system having optical endpoint control and associated method

Large machines, especially those having working envelopes in excess of fifteen feet, exhibit unacceptable errors because of thermal expansion and mechanical misalignments between the axes. The errors have traditionally been minimized by enclosing the machine in a thermal enclosure, by careful calibration, or by mounting a laser interferometer on each axis. These solutions are costly, may require frequent recalibration, and do not correct for small rotations of one axis relative to another axis due to wear etc. The present invention uses an interferometric laser tracker or a comparable 3D position sensor to measure the position of a retroreflector attached to the end effector, e.g. a machine head when the machine comes to rest. A computer compares the measured position to the desired position according to the machine media, and adds the appropriate correction with trickle feed media statements to move the machine to the correct position prior to further machining. The present invention scales the media statements for changes in the part that occur during its manufacture or inspection.

Real-time orientation of machine media to improve machine accuracy

Large machines, especially those having working envelopes in excess of fifteen feet, exhibit unacceptable errors because of thermal expansion and mechanical misalignments between the axes. The present invention uses an interferometric laser tracker or a comparable 3D position sensor to measure the position of a retroreflector attached to the end effector, e.g. a machine head when the machine comes to rest. A computer compares the measured position to the desired position according to the machine media, and adds the appropriate correction with trickle feed media statements to move the machine to the correct position prior to further machining. The present invention scales the media statements for thermal effects in the factory.

Scaling machine media for thermal effects to improve machine accuracy

Product acceptance requires accurate measurement of product features. We augment machine control with true position feedback from an independent measurement system to allow such inspection to occur with conventional machine tools rather than expensive, special purpose, limited versatility Coordinate Measuring Machines.

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Sumner, WA, United States of America

Thomas A Greenwood