Shape Measuring Probe Control Vector Orthogonalization
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Solution Overview
Problem
Existing shape measuring apparatuses face instability in controlling the movement of a probe during active nominal scanning measurement, as the direction of the trajectory correcting vector opposes the deflection correcting vector, leading to vibration and a trade-off between trajectory correcting capability and control stability.
Innovation Solution
A method that generates a combined velocity vector incorporating a second trajectory correcting vector orthogonal to both the deflection correcting vector and path velocity vector, allowing for stable control by minimizing interference between vectors, thereby maintaining constant deflection and correcting trajectory effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a trajectory correcting vector is used to correct the probe position, then the trajectory correcting capability is improved, but the control stability deteriorates due to opposition with the deflection correcting vector
Solution Approach 1:
The patent introduces a second trajectory correcting vector that is orthogonal to both the deflection correcting vector and the path velocity vector, adding a new dimension to the correction mechanism. This orthogonal vector resolves the conflict between trajectory correction and control stability by operating in a direction perpendicular to the existing correction vectors, allowing simultaneous optimization of both trajectory accuracy and control stability.
2Stability of the object's composition
If the gains Ge or Gc are reduced to suppress vibration, then the control stability is improved, but the trajectory correcting capability and deflection correcting capability decrease
Solution Approach 1:
By introducing the second trajectory correcting vector in an orthogonal direction, the patent enables independent optimization of correction gains. The orthogonal component allows the system to maintain higher gain values for trajectory correction without causing instability, as the correction actions are decomposed into independent orthogonal components that do not interfere with each other.
3Measurement precision
If the direction of the trajectory correcting vector opposes the deflection correcting vector, then the trajectory correction is enhanced, but probe vibration increases
Solution Approach 1:
The patent resolves the opposing vector conflict by introducing a second trajectory correcting vector that is orthogonal to the deflection correcting vector. This dimensional change ensures that the trajectory correction force does not directly oppose the deflection correction force, eliminating the vibration-causing conflict while maintaining effective trajectory correction through the orthogonal component.
Data Source
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AI summary
There is provided a method for controlling a shape measuring apparatus which can achieve both trajectory correcting capability and control stability. A stylus tip is moved along a scanning path while controlling the stylus tip so as to keep an amount of deflection of a probe to a workpiece to be a reference amount of deflection. A movement instruction for the probe is generated according to a combined velocity vector V represented by the following expression: combined velocity vector V=Gf⋅Vf+Ge⋅Ve+Gc⋅Vc2, where Vf is a path velocity vector to move the probe along the scanning path, Ve is a deflection correcting vector to keep the amount of deflection of the probe to the workpiece to be the reference amount of deflection, Vc2 is a second trajectory correcting vector represented by (Vc1.q)q, Vc1 is a first trajectory correcting vector to correct a position of the probe so that the stylus tip heads to the scanning path, and q is a trajectory correcting direction vector given by a vector product of a normal line of a surface of the workpiece and the path velocity vector Vf.