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Machine motion trajectory measuring device, numerically controlled machine tool, and machine motion trajectory measuring method

  • US 9,144,869 B2
  • Filed: 09/10/2009
  • Issued: 09/29/2015
  • Est. Priority Date: 12/09/2008
  • Status: Active Grant
First Claim
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1. A machine motion trajectory measuring device for measuring a motion trajectory of a machine position, wherein the machine position is a relative position of a tool of a machine with respect to a work table controlled by a motor, a motor position of the motor being detected by a detector, and the motor is driven such that the detected motor position follows a commanded position, the machine motion trajectory measuring device comprising:

  • an accelerometer for measuring acceleration of the tool of the machine or the work table; and

    a motion trajectory measuring unit which measures the motion trajectory of the machine position byobtaining the measured acceleration measured by the accelerometer,determining motion trajectory error occurring regions, in which a trajectory error is expected to occur, based on a rate of change of the acceleration obtained by differentiating the commanded position three times and exceeding a preset threshold value, and a reversal of a sign of a commanded velocity obtained by differentiating the commanded position,extracting the measured acceleration at the motion trajectory error occurring regions,integrating the measured acceleration at the motion trajectory error occurring regions twice to compute the machine position,correcting errors for the computed machine position such that a profile of the corrected machine position coincides with a profile of the detected motor position or with a profile of an estimated position estimated using a model for simulating a response of the machine position to the commanded position, andobtaining a trajectory of the corrected machine position as the motion trajectory of the machine position.

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