Method for calibrating a coordinate measuring machine and the like and system therefor
First Claim
1. Method for calibrating a CMM (10) having a measuring volume (102), the CMM including a probe shaft (22) having three axes of motion (X, Y and Z), a probe (14) supported on a distal end of the probe shaft, devices for providing a position signal in determining the position of the probe for each of the axes of motion in the coordinate frame of the CMM and control means (36) for receiving the position signals and for providing a coordinate measurement signal which identifies the position of the probe, the method including the steps of:
- moving (FIGURES 4A through 4C) the CMM from a first predetermined position to a plurality of other predetermined positions along the length of each of the axes of motion so as to generate position signals in the coordinate frame of the CMM;
measuring (FIGS. 4A through 4C) the positions to obtain measured calibration data;
processing (FIGS. 4A through 4C) the position signals and the calibration data, said step of processing including the step of correlating (FIGS. 4A through 4C) the position signals and the calibration data to obtain axis correction data for each of said predetermined positions;
said step of processing further providing squareness data (84, 94 and
96) representing the orthogoninality of the axes, storing (108) the axis correction data in a form which can be utilized by the control means during operation of the CMM to compensate the CMM for the entire measuring volume and wherein the improvement comprises the steps of;
(a) installing (FIG. 5A) an artifact on the CMM in a first position within a plane defined by a first pair of the axes of motion, the artifact having two ends separated by a distance;
(b) moving (FIG. 5A) the artifact to a second position within the plane;
(c) moving (86) the probe so that the CMM generates coordinate data representing the positions defined by the ends of the artifact in each of the positions; and
(d) repeating steps (a) through (c) for second and third pairs of the axes of motion the coordinate data being utilized in said step of processing to provide the squareness data for calibrating the CMM.
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Accused Products
Abstract
Method (FIGS. 4A through 4C) and system (FIG. 3) are disclosed for automatically calibrating a coordinate measuring machine (CMM) (10). The system guides an operator through instrument set-up and data collection procedures. The system automatically converts the collected data into error compensation or axis correction data which represents 21 different geometry errors (i.e. pitch, yaw, roll etc.) of the CMM (10). The error compensation data is then transferred to a CMM measurement processor (36) for subsequent use by the CMM (10) during operation thereof to thereby compensate the CMM (10) for its entire measuring volume (102).
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Citations
16 Claims
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1. Method for calibrating a CMM (10) having a measuring volume (102), the CMM including a probe shaft (22) having three axes of motion (X, Y and Z), a probe (14) supported on a distal end of the probe shaft, devices for providing a position signal in determining the position of the probe for each of the axes of motion in the coordinate frame of the CMM and control means (36) for receiving the position signals and for providing a coordinate measurement signal which identifies the position of the probe, the method including the steps of:
- moving (FIGURES 4A through 4C) the CMM from a first predetermined position to a plurality of other predetermined positions along the length of each of the axes of motion so as to generate position signals in the coordinate frame of the CMM;
measuring (FIGS. 4A through 4C) the positions to obtain measured calibration data;
processing (FIGS. 4A through 4C) the position signals and the calibration data, said step of processing including the step of correlating (FIGS. 4A through 4C) the position signals and the calibration data to obtain axis correction data for each of said predetermined positions;
said step of processing further providing squareness data (84, 94 and
96) representing the orthogoninality of the axes, storing (108) the axis correction data in a form which can be utilized by the control means during operation of the CMM to compensate the CMM for the entire measuring volume and wherein the improvement comprises the steps of;(a) installing (FIG. 5A) an artifact on the CMM in a first position within a plane defined by a first pair of the axes of motion, the artifact having two ends separated by a distance; (b) moving (FIG. 5A) the artifact to a second position within the plane; (c) moving (86) the probe so that the CMM generates coordinate data representing the positions defined by the ends of the artifact in each of the positions; and (d) repeating steps (a) through (c) for second and third pairs of the axes of motion the coordinate data being utilized in said step of processing to provide the squareness data for calibrating the CMM. - View Dependent Claims (2, 3, 4, 7, 8, 9, 10, 11, 12, 13, 16)
- moving (FIGURES 4A through 4C) the CMM from a first predetermined position to a plurality of other predetermined positions along the length of each of the axes of motion so as to generate position signals in the coordinate frame of the CMM;
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5. The method as claimed in clam 4 wherein said step of processing includes the steps of:
- translating (72) at least one set of the straightness data to a predetermined point in the sets of the rotation data; and
normalizing (72) at least one set of the straightness data to a best fit line. - View Dependent Claims (6)
- translating (72) at least one set of the straightness data to a predetermined point in the sets of the rotation data; and
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14. A system (FIG. 3) for calibrating a CMM (10) having a measuring volume (102), the CMM including a probe shaft (22) having at least one axis of motion (X, Y or Z), a device for providing a position signal in determining the position of the probe for the axis of motion in the coordinate frame of the CMM and control means (36) for receiving the position signal and for providing a coordinate measurement signal, the system comprising at least one calibration device (32) for measuring the position of the CMM in a standard coordinate frame having a standard axis system at a plurality of predetermined positions along he axis of motion of the CMM to obtain measured calibration data, the device generating the position signal in the coordinate frame of the CMM;
- and data processing means (34) for processing the position signal and the calibration data, the improvement comprising;
the data processing means including means (FIGS. 4A through 4C) for correlating the position signal and the calibration data to obtain axis correction data for each of said predetermined positions; and storage means (11)) for storing the axis correction data in a form which can be utilized by the control means during operation of the CMM for the entire measuring volume.
- and data processing means (34) for processing the position signal and the calibration data, the improvement comprising;
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15. A system (FIG. 3) for calibrating a CMM (10) having a measuring volume, the CMM including a probe shaft (22) having three axes of motion (X,Y,Z) devices for providing a position signal for each of the axes of motion in the coordinate frame of the CMM and control means (36) for receiving the position signals and for providing a coordinate measurement signal, the system comprising at least one calibration device (32) for measuring the position of the CMM in a standard coordinate frame having a standard axis system at a plurality of predetermined positions of the CMM to obtain measured calibration data, the devices generating feedback data in the coordinate frame of the CMM;
- and data processing means (34) for processing the position signals and the calibration data, the improvement comprising;
the data processing means including means (FIGS. 4A through 4C) for correlating the position signals and the calibration data to obtain axis correction data for each of said predetermined positions; and storage means (110) for storing the axis correction data in a form which can be utilized by the control means during operation of the CMM to compensate the CMM for the entire measuring volume.
- and data processing means (34) for processing the position signals and the calibration data, the improvement comprising;
Specification