Numerical Controller Tool Path Optimization
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Solution Overview
Problem
Conventional numerical controllers do not effectively consider movement time when determining tool paths to start or restart positions during cutting, leading to longer processing times due to excessive acceleration/deceleration caused by multiple breakpoints, which can be more time-consuming than longer paths with fewer breakpoints.
Innovation Solution
A numerical controller that includes a shortest-path creation unit, an alternative path creation unit, and a movement time prediction unit to determine a tool path that minimizes movement time by selecting paths with fewer breakpoints while avoiding interference, thereby optimizing movement time and reducing the number of acceleration/deceleration events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the shortest path is selected to minimize movement distance, then the movement distance is shortened, but the number of breakpoints increases leading to longer movement time due to excessive acceleration/deceleration
Solution Approach 1:
The patent changes the optimization parameter from purely minimizing movement distance to minimizing movement time. The movement time calculation incorporates acceleration and deceleration phases at each breakpoint, allowing the system to select paths that may be longer in distance but have fewer breakpoints, thereby reducing total movement time.
Solution Approach 2:
The patent introduces dynamic consideration of tool motion by calculating movement time based on acceleration and deceleration at breakpoints. This dynamic approach allows the system to adapt path selection based on motion characteristics rather than static distance minimization, resolving the contradiction between short distance and short time.
2Loss of time
If paths with fewer breakpoints are selected to reduce acceleration/deceleration events, then movement time is shortened, but the movement distance may increase
Solution Approach 1:
The patent shifts the optimization criterion from distance minimization to time minimization. By calculating total movement time including acceleration and deceleration phases, the system can identify paths that are longer in distance but have fewer breakpoints, thus achieving shorter overall movement time.
Solution Approach 2:
The patent allows the tool to take paths that skip intermediate breakpoints compared to the shortest geometric path. By accepting longer distances in exchange for fewer acceleration/deceleration cycles, the system effectively 'skips' the time-consuming repeated stops and starts.
3Reliability
If the shortest path with many breakpoints is used, then interference avoidance is achieved, but motor life is reduced and power consumption increases due to frequent acceleration/deceleration
Solution Approach 1:
The patent changes the optimization objective to minimize movement time while maintaining interference avoidance. This parameter change naturally reduces the number of acceleration/deceleration events, thereby extending motor life and reducing power consumption while still ensuring the tool path avoids interfering objects.
Solution Approach 2:
The patent incorporates feedback by calculating movement time for different path options and selecting the optimal path. This feedback mechanism allows the system to evaluate paths based on actual motor operation characteristics (acceleration/deceleration events) rather than simple geometric distance, leading to reduced motor wear and energy consumption.
Data Source
AI summary
A numerical controller first creates a shortest path which does not interfere with an interfering object and shortens a movement distance from a start point to a cutting start position, and then, creates one or more alternative paths having a smaller number of break points than the shortest path when determining a movement path of a tool from the start point to the cutting start position. Then, each of a movement time along the shortest path and a movement time along the alternative path is calculated, and the alternative path having the shorter movement time than the shortest path is determined as the movement path.