Parallel Link Motion Control for Constant-Speed Corner Tracking
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Solution Overview
Problem
Existing link actuation devices with combined parallel and linear motion mechanisms face challenges in maintaining constant speed while working on boundary surfaces with sharp angles, leading to processing unevenness during operations like laser processing, coating, and welding.
Innovation Solution
A control device that divides the working path into straight and corner areas, allowing the end effector to maintain constant speed by coordinating the parallel and linear motion mechanisms, ensuring continuous operation without acceleration or deceleration, particularly in corner areas where the end effector passes over sharp angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the end effector moves along boundary surfaces with sharp angles using conventional control methods, then the working path can be completed, but the speed varies causing processing unevenness
Solution Approach 1:
The working path is segmented into straight sections and corner sections. In straight sections, only the linear motion mechanism operates at constant speed. In corner sections, both linear motion and parallel link mechanisms coordinate to maintain constant speed through the sharp angle boundary. This segmentation allows different control strategies for different path segments, resolving the speed uniformity issue.
Solution Approach 2:
The control system dynamically adjusts the coordination between linear motion mechanism and parallel link mechanism based on the current position. When approaching corner areas with sharp angles, the system transitions from linear-only motion to coordinated motion, dynamically maintaining constant speed throughout the entire path including boundary surfaces.
2Productivity
If the end effector continuously operates along the working path including corner areas, then productivity is improved, but maintaining constant speed through sharp angles becomes difficult
Solution Approach 1:
The control device enables continuous operation of the end effector along the entire working path without stopping or accelerating/decelerating at corners. By coordinating linear motion and parallel link mechanisms, the system maintains continuous constant-speed motion through sharp angle boundaries, ensuring both productivity and processing uniformity.
3Adaptability or versatility
If the parallel link mechanism is used to reach boundary surfaces, then adaptability to complex workpieces is improved, but control complexity increases
Solution Approach 1:
The control space is segmented into regions requiring only linear motion and regions requiring parallel link mechanism activation. By dividing the working path into straight and corner sections, the system activates the more complex parallel link mechanism only when necessary (in corner areas), reducing overall control complexity while maintaining adaptability.
Solution Approach 2:
Different control strategies are applied to different regions of the working path. Straight sections use simple linear motion control, while corner sections use coordinated control of both mechanisms. This local differentiation optimizes control complexity by applying advanced control only where geometric constraints require it.
Data Source
AI summary
An operation command generator includes: an area division unit configured to divide a line on a flat work surface of a target workpiece W into a straight area and a corner area, using a sharp boundary surface; a straight area operation command generation unit configured to generate a command for operating only the linear motion mechanism while keeping the posture of the parallel link mechanism fixed, in the straight area; and a corner area operation command generation unit configured to generate a command so that an acting point of the end effector passes on the boundary surface at a substantially constant speed by the linear motion mechanism and the parallel link mechanism performing coordinated operations in the corner area.