Parallel Link Path Control for Constant-Speed Corner Processing
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Solution Overview
Problem
Existing control devices for link actuation systems struggle to maintain constant speed on boundary surfaces with sharp angles, leading to processing unevenness during laser processing, coating, or welding on three-dimensional workpieces.
Innovation Solution
A control device that divides the working path into straight and corner areas, using a parallel link mechanism and linear motion mechanism to maintain constant speed by coordinating the end effector's movement along the boundary surface, ensuring continuous operation without acceleration or deceleration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the end effector is activated and stopped during series of operations to act on each side surface separately, then the operation can be completed on the entire periphery of the workpiece, but a joint (discontinuity) occurs at the boundary part of the side surface
Solution Approach 1:
The patent applies continuity of useful action by keeping the end effector activated continuously during corner transitions. The control device coordinates the linear motion mechanism and parallel link mechanism to move the end effector along a continuous path that includes arc interpolation movements, eliminating stop-and-start operations and preventing joint discontinuities at boundary parts.
Solution Approach 2:
The patent uses curvature by implementing arc interpolation movements at corner portions. Instead of moving in straight lines between sides, the end effector follows curved paths with central angles (e.g., 90°) at corners, allowing smooth continuous operation without abrupt direction changes or stopping.
2Reliability
If the XY stage performs arc interpolation movement and the parallel link mechanism turns at the corner to maintain continuous end effector action, then the end effector acts excessively on the corner point
Solution Approach 1:
The patent applies feedback by using a sensor to detect the position of the end effector and feed this information back to the control device. The control device calculates the actual position and adjusts the movement commands for the linear motion mechanism and parallel link mechanism to ensure the end effector moves at a substantially constant speed, preventing excessive action at corner points.
Solution Approach 2:
The patent applies dynamics by transitioning from static point-to-point positioning to dynamic continuous path control. The system calculates movement amounts and speeds in real-time based on the detected end effector position, allowing the end effector to maintain substantially constant speed during arc interpolation movements and coordinate operations.
3Productivity
If the end effector moves at varying speed during corner operations, then the operation can be completed, but processing unevenness occurs on the boundary surface
Solution Approach 1:
The patent uses feedback control to maintain substantially constant speed of the end effector. The sensor detects the end effector position, and the control device calculates the required movement amounts and speeds for the linear motion mechanism and parallel link mechanism to keep the speed uniform, preventing processing unevenness on boundary surfaces.
Solution Approach 2:
The patent applies parameter changes by dynamically adjusting the movement parameters (movement amounts and speeds) of the linear motion mechanism and parallel link mechanism based on the operational phase (straight area vs. corner area). This allows the system to maintain constant end effector speed while completing the operation.
Data Source
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AI summary
An operation command generator (70) includes: an area division unit (67) configured to divide a line (L) on a flat work surface (S) of a target workpiece W into a straight area (LS) and a corner area (LC), using a sharp boundary surface (B); a straight area operation command generation unit (68) configured to generate a command for operating only the linear motion mechanism (31) while keeping the posture of the parallel link mechanism (1) fixed, in the straight area (LS); and a corner area operation command generation unit (69) configured to generate a command so that an acting point (P) of the end effector (29) passes on the boundary surface (B) at a substantially constant speed by the linear motion mechanism (31) and the parallel link mechanism (1) performing coordinated operations in the corner area (LC).