Five-Axis Probe Head Control for Interference-Free Measurement
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Solution Overview
Problem
Shape measuring apparatuses with five-axis control face challenges in predicting the movement path of measurement tips, leading to potential interference with workpieces during measurement, as the trajectory of the measurement tip is difficult to predict until the measurement is performed.
Innovation Solution
A method for controlling a shape measuring apparatus that calculates interpolation points for each drive axis, sets a rotation center, and synchronizes speed patterns across all axes to ensure a predictable movement path, such as a straight line or arcuate path, to avoid interference with the workpiece.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If five-axis control is implemented to measure complicated workpieces at high speed, then productivity is improved, but the movement path of the measurement tip becomes unpredictable, leading to potential interference with the workpiece
Solution Approach 1:
The control method calculates and determines the complete movement trajectory of the measurement tip before actual measurement begins. By pre-computing the path considering all five axes coordination, the system predicts the exact trajectory and takes preliminary actions to avoid workpiece interference, thus maintaining both high speed and reliability
2Reliability
If the operator manually monitors the probe head during movement to prevent interference, then reliability is improved, but the complexity of operation increases and productivity decreases
Solution Approach 1:
The control method incorporates automated feedback mechanisms where the control device continuously monitors the calculated trajectory and compares it with the workpiece geometry. This automated feedback loop prevents workpiece interference without requiring manual operator intervention, maintaining reliability while improving ease of operation and productivity
3Device complexity
If the measurement tip moves to the target point using individual axis control, then device complexity is reduced, but the movement path cannot be predicted and interference with the workpiece may occur
Solution Approach 1:
The control method merges the control of all five axes into a unified coordination system. By integrating the control commands for three translational axes and two rotational axes, the system calculates the combined effect on the measurement tip trajectory, enabling prediction and prevention of workpiece interference while maintaining relatively simple individual axis mechanisms
Data Source
AI summary
A shape measuring apparatus includes a probe head that changes its posture by rotational motion of a first drive axis and a second drive axis, and a coordinate measuring machine that three-dimensionally displaces a location of the probe head by three translation axes (a third drive axis, a fourth drive axis, and a fifth drive axis). The location of a measurement tip is given by coordinate values of the third to fifth drive axes, and the posture of a probe head is given by a first rotating angle α and a second rotating angle β. An intersection point between a first rotation axis and a second rotation axis is set as a rotation center Q. An interpolation point in each control period is calculated for each of the first to fifth drive axes.