CNC Motion Planning for Disconnected Contours
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Solution Overview
Problem
Existing CNC machining technologies face limitations in production rate and energy efficiency due to 'stop-and-start' motions, which are suboptimal for high-speed machining and lead to machine wear, especially when dealing with patterns of disconnected contours.
Innovation Solution
A system and method for generating dynamically optimized motion plans that allow the tool-head to enter and exit contours on a tangent, with velocity profiles matching the curvature and dynamics of the machine, using curved traverse trajectories and optimization techniques to determine the most efficient sequence of trajectories and instructions for controlling the machine.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If stop-and-start motions are used for machining disconnected contours, then the machine can easily reposition between contours, but the production rate is limited and energy consumption increases due to frequent accelerations and decelerations
Solution Approach 1:
The patent implements continuous motion machining where the cutting tool remains engaged with the workpiece throughout the entire machining process, eliminating stop-and-start cycles. The tool head maintains constant motion by transitioning from cutting one contour to traversing to the next contour without stopping, thereby maintaining continuous useful action and improving production rate while reducing energy consumption associated with repeated acceleration and deceleration cycles
2Speed
If straight traverses are used between contours in on-the-fly machining, then the machine can maintain high speed, but the traverse paths are suboptimal and do not consider machine dynamics
Solution Approach 1:
The patent applies dynamic optimization to traverse trajectories by considering the specific dynamics of the laser cutter machine. The motion planner calculates optimal traverse paths that account for acceleration and deceleration characteristics, ensuring that the tool head can transition between contours at maximum speed while respecting the machine's dynamic constraints. This dynamic approach optimizes both speed and reliability of the machining process
3Productivity
If straight traverses are replaced with optimized trajectories, then the machining becomes more efficient, but the planning problem becomes much more complicated
Solution Approach 1:
The patent introduces a sophisticated motion planning system that acts as an intermediary between the machining requirements and the machine execution. This planning system computes optimized trajectories that consider machine dynamics, contour geometry, and speed requirements, translating complex machining objectives into executable motion commands. The intermediary planner handles the computational complexity of generating dynamically optimized paths, allowing the machine to achieve maximum efficiency without requiring complex manual programming
Data Source
AI summary
A set of costs representing operations of a machine along a set of trajectories connecting a set of exit and entry points on contours of a pattern is determined. Each trajectory represents an operation of the machine proceeding from an exit point with an exit velocity to an entry point with an entry velocity according to dynamics of the machine. The set of trajectories includes at least one trajectory representing the operation along a contour with non-zero velocities at corresponding exit and entry points, and at least one trajectory representing the operation between different contours with non-zero velocities at the corresponding exit and entry points. A sequence of the trajectories optimizing a total cost of operation of the machine tracking the pattern is determined based on the costs, and a set of instructions for controlling the machine is determined according to the sequence.