Trajectory Control Device for Boundary Error Correction
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Solution Overview
Problem
Existing trajectory control methods fail to effectively correct trajectory errors in boundary portions between straight lines and curved lines, leading to machining defects such as protrusions or parallel grooves due to transitional changes in error magnitude and direction.
Innovation Solution
A trajectory control device that includes a servo-system response-trajectory calculation unit, a shape-feature determination unit, and a position-vector correction unit, which computes and corrects position commands based on shape features to limit trajectory errors by simultaneously controlling motors of multiple axes, ensuring precise alignment along commanded paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If trajectory error correction is applied using estimated error values, then trajectory precision is improved in curved portions, but trajectory errors remain uncorrected in boundary portions between straight lines and curves
Solution Approach 1:
The commanded path is segmented into three distinct regions: straight line portions, curved portions, and boundary portions. Each region is identified and processed with appropriate correction strategies, allowing the system to address the unique characteristics of boundary portions where traditional correction methods fail.
Solution Approach 2:
Different correction approaches are applied to different path regions. Boundary portions receive specialized correction handling distinct from curved portions, with the system adjusting correction amounts based on local path characteristics to ensure effective error compensation throughout the entire trajectory.
2Adaptability or versatility
If correction amount changes transitionally in boundary portions, then correction adapts to changing error characteristics, but the correction amount becomes different from ideal correction amount
Solution Approach 1:
The system performs preliminary identification of boundary portions before executing trajectory correction. By detecting boundary portions in advance and applying predetermined correction strategies, the system prevents the generation of excessive or insufficient correction amounts that would otherwise occur with transitional correction approaches.
Solution Approach 2:
The commanded path is analyzed in advance to identify and mark boundary portions between straight lines and curves. This preliminary action allows the control system to prepare appropriate correction amounts for each region before actual machining begins, ensuring optimal correction is applied without overshooting or undershooting.
Data Source
AI summary
A trajectory control device controlling a trajectory of a movable portion includes a servo-system response-trajectory calculation unit that computes a servo-system response trajectory based on a position command of each movable axis, a shape-feature determination unit that outputs a shape feature amount including information of a position of a boundary point in a path shape and a running direction near the boundary point based on a determination from the position command whether the shape of the commanded path is straight or curved line, a position-vector correction unit that corrects a position vector based on the position command, the servo-system response trajectory and the shape feature amount, and outputs a corrected position command, and servo control units that control a motor of each movable axis by outputting a motor drive torque so that a position of each movable axis follows the corrected position command.