Normal-line detection using orthogonal distance sensors
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Solution Overview
Problem
Existing methods for detecting the normal-line direction of a curved processing surface, such as those in PTL 1 and PTL 2, face challenges in ensuring sufficient space for processing machines and obtaining accurate axis alignment due to the need for rotating distance sensors and inadequate control information.
Innovation Solution
A normal-line detection device with four or more distance measurement means arranged on the periphery of a processing machine, intersecting with the processing shaft axis, calculates an approximation surface based on measured values and angles to determine the normal-line direction, even in the presence of unevenness, ensuring space for the machine and aligning the processing shaft with the normal-line.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If distance sensors are arranged around the rotation center or a rotation mechanism is used, then normal-line detection capability is improved, but space for arranging processing machine cannot be ensured
Solution Approach 1:
The patent transitions from arranging sensors in a circular pattern around the rotation center (2D radial arrangement) to arranging four sensors on a plane orthogonal to the processing shaft axis (2D planar arrangement). This dimensional change allows sensors to be positioned at corners of a rectangle on the periphery, providing sufficient space for the processing machine while maintaining normal-line detection capability through geometric calculation from four measurement points.
2Measurement precision
If complex sensor arrangements and rotations are used, then normal-line detection accuracy is improved, but device complexity increases
Solution Approach 1:
The patent divides the normal-line detection function into four separate distance measurement means positioned at the corners of a rectangle. Each sensor independently measures distance to the processing surface, and the calculation unit segments the computation by determining coordinates of four measurement positions and calculating the approximation plane from these discrete points, simplifying the overall system architecture.
Solution Approach 2:
The patent replaces the mechanical rotation mechanism (rotating the sensor or workpiece) with a static four-sensor arrangement. Instead of mechanically rotating a single sensor to collect data at multiple angles, the system uses four fixed sensors positioned orthogonally, eliminating mechanical complexity while achieving the same measurement objective through geometric calculation.
3Measurement precision
If four or more measurement positions are used, then normal-line detection on uneven surfaces is improved, but sufficient control information for axis alignment cannot be obtained
Solution Approach 1:
The patent establishes a feedback loop where the calculation unit computes the approximation plane from four measurement positions and determines the normal line of this plane. The normal-line detection unit then uses this normal line information to provide control feedback for aligning the processing shaft axis with the detected normal line, ensuring both accurate detection on uneven surfaces and proper axis alignment.
Solution Approach 2:
The four measurement positions serve multiple functions simultaneously: they define the approximation plane geometry, provide normal-line direction information, and enable axis alignment control. This multi-functionality ensures that the same set of measurements used for detecting normal lines on uneven surfaces also provides sufficient control information for aligning the processing shaft, eliminating information loss.
Data Source
AI summary
A normal-line detection device is provided with: four or more non-contacting distance sensors for measuring the distance to a processing surface of a work piece, the non-contacting distance sensors being arranged on the periphery of a drill body, in an arrangement plane orthogonal to an axis line of the drill body, and a distance measurement axis of each non-contacting distance sensor and the axis line intersecting; and a PC for calculating an approximation surface of a processing surface on the basis of measurement values from the non-contacting distance sensors and the angle of the non-contacting distance sensors with respect to the axis line, and determining the normal-line of the approximation surface as the normal-line of the processing surface.