Apparatus and method to provide high accuracy calibration of machine tools
First Claim
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1. A device for calibrating a precision machining tool to determine the pitch, roll and yaw angular deviations of a movable member of the machining tool relative to a fixed machine base of the machining tool, the device comprising:
- a movable member associated with the machining tool for moving a workpiece relative to the cutting tool, the movable member having a full range of motiona sensor assembly attached to the movable member and responsive to motion along three orthogonal axes, the sensor assembly providing an output indicative of sensed yaw motion, sensed pitch motion, and sensed roll motion;
a position sensor attached to the movable member for producing a position output indicative of the position of the movable member relative to a predetermined starting point; and
a processing unit attached to the sensor assembly output and the position output for collecting data as the movable member is exercised through its full range of motion and for calculating an angle deviation as a function of the movable member'"'"'s position relative to the starting point.
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Abstract
A sensor assembly along with numerous processing equipment is provided for attachment to the work table of a precision machining system. By attaching the device to the work table and subsequently driving the work table through a repeated pattern of motions, the actual movement of the table can be precisely determined and, consequently, can be compensated for. The sensor assembly utilizes a plurality of gyroscopes and accelerometers to determine actual movement in inertial space.
41 Citations
23 Claims
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1. A device for calibrating a precision machining tool to determine the pitch, roll and yaw angular deviations of a movable member of the machining tool relative to a fixed machine base of the machining tool, the device comprising:
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a movable member associated with the machining tool for moving a workpiece relative to the cutting tool, the movable member having a full range of motion a sensor assembly attached to the movable member and responsive to motion along three orthogonal axes, the sensor assembly providing an output indicative of sensed yaw motion, sensed pitch motion, and sensed roll motion; a position sensor attached to the movable member for producing a position output indicative of the position of the movable member relative to a predetermined starting point; and a processing unit attached to the sensor assembly output and the position output for collecting data as the movable member is exercised through its full range of motion and for calculating an angle deviation as a function of the movable member'"'"'s position relative to the starting point. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A calibration apparatus for detecting the pitch, roll and yaw angular deviations in the movement of a table as it translates down a track of a numerically controlled machine tool relative to a fixed machine base of the machine tool thus providing a correction function to allow for compensation of these angular deviations, the calibration apparatus comprising;
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a sensor assembly attached to the table for detecting inertial motion of the table as it traverses the track, said sensor assembly having an inertial sensor output; a position encoder attached to the machine tool for determining the position of the table relative to the machine tool, the position encoder having a position output; summing means attached to the inertial sensor output for receiving data and summing it over a period of time to produce a cumulative sensor output; first filtering means attached to the summing means for receiving the cumulative sensor output and producing a filtered sensor output, wherein the filtering means eliminates noise according to a predetermined filter function; second filtering means attached to the position encoder for receiving the position output and producing a filtered position output, wherein the filtering means eliminates noise according to the predetermined filter function; and processor means having a control output attached to the sensor assembly and the position encoder for coordinating the operation of the sensor assembly and the position encoder so as to trigger the reading of a plurality of sets of sensor readings and position readings and consequently a plurality of sets of filtered position outputs and filtered sensor outputs, wherein the processor means also accumulates the plurality of sets of filtered position outputs and plurality of sensor outputs and produces a cumulative set of position versus inertial motion data for an entire traversal of the track. - View Dependent Claims (14, 15, 16, 17, 18, 19)
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20. A method of determining pitch, roll and yaw angular deviation in the movement of a movable member of a numerically controlled precision machining tool relative to a fixed machine base of the machining tool, the method comprising the steps of:
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exercising the movable member of the numerically controlled precision machining tool through its full range of motion in both a forward and reverse direction; accumulating sensor data from an inertial sensor assembly attached to the movable member while the movable member is exercised; accumulating position data from a position encoder attached to the movable member wherein the position encoder provides a signal indicative of the position of the movable member relative to a predetermined starting point; partitioning the movable member'"'"'s range of motion into a plurality of segments such that each segment represents a portion of the full range of motion; identifying the data from the inertial sensor assembly that corresponds to each segment, wherein the data corresponding to each segment will include forward data from the forward motion of the movable member and reverse data from the reverse motion of the movable member; and processing the identified data for each segment to determine the angular deviation of the movable member relative to the fixed machine base for that segment, wherein the processing includes the steps of adding the forward data and the reverse data for each segment to determine a true angular deviation for that segment free of any constant error terms, and accumulating the true angular deviation for all the segments to determine an angular deviation function for the entire range of motion of the movable member. - View Dependent Claims (21, 22, 23)
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Specification