Profile Measuring Apparatus Control Vector Stability
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Solution Overview
Problem
Existing profile measuring apparatuses face instability in control due to opposing directions of course correction and deflection correction vectors, leading to oscillation and compromised performance in both course correction and deflection correction.
Innovation Solution
A control method that generates a composite speed vector incorporating a second course correction vector orthogonal to the path speed and deflection correction vectors, using a mathematical sign determination function to adjust the direction of the second course correction vector based on its scalar product with the nominal normal direction vector, ensuring stability and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the course correction vector and deflection correction vector are used in active nominal scanning measurement, then course correction performance and deflection correction performance are improved, but control stability deteriorates due to oscillation caused by opposing vector directions
Solution Approach 1:
The course correction vector is decomposed into two orthogonal components: one component orthogonal to both the path speed vector and deflection correction vector, and another component parallel to the deflection correction vector. This segmentation allows independent control of each component's contribution to the composite vector, preventing oscillation while maintaining correction effectiveness.
Solution Approach 2:
Different components of the course correction are applied with different characteristics. The orthogonal component provides stable course correction without interfering with deflection correction, while the parallel component is carefully controlled to supplement rather than conflict with the deflection correction action, creating locally optimized correction behavior.
2Stability of the object's composition
If the gains Ge or Gc are reduced to inhibit oscillating behavior, then control stability is improved, but course correction performance and deflection correction performance are diminished
Solution Approach 1:
By segmenting the course correction vector into orthogonal and parallel components, the system can apply appropriate gain values to each component independently. The orthogonal component can use higher gain for effective course correction, while the parallel component uses controlled gain to avoid oscillation, thereby maintaining both stability and correction performance.
Solution Approach 2:
The invention changes the parameter structure by introducing a new vector component orientation (orthogonal to both path speed and deflection correction vectors). This parameter change allows the system to achieve effective course correction without the oscillatory behavior that limited gain adjustments in the conventional approach.
3Ease of operation
If the course correction vector is applied to correct probe position, then the stylus tip is oriented along the scanning course, but interference with deflection correction occurs causing oscillation
Solution Approach 1:
The course correction vector is segmented into an orthogonal component that handles scanning course alignment and a parallel component that could interfere with deflection correction. By isolating the alignment function to the orthogonal component, the system achieves scanning course orientation without creating oscillatory interference with deflection correction.
Solution Approach 2:
The harmful interfering component of the course correction vector (the part parallel to the deflection correction vector) is extracted and separately controlled. This extraction removes the source of oscillation while preserving the beneficial course alignment function through the orthogonal component.
Data Source
AI summary
A probe displacement command in a scanning measurement is generated according to a composite speed vector V:V=Gf·Vf+Ge·Ve+sp(p)·Gc·Vc2wherein Vf is a vector along which a probe is displaced along a scanning path, Ve is a vector maintaining a deflection amount of the probe toward a work piece at a standard deflection amount. Vc2 is represented by (Vc1·q)q, Vc1 is a vector in a direction correcting a probe position such that a stylus tip is oriented along a scanning course, q is a vector given by a vector product of the normal line of a surface of the work piece and Vf, The normal direction of a measured surface is designated as Nw, p is a scalar product of Vc2 and Nw, and sg(p) is a function returning +1 or −1 in accordance with a value of p.