NC Motion Control Using Reverse Interpolation Speed Planning
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing numerical control devices face challenges in efficiently managing the movement time and computational load for acceleration/deceleration processes, as permissible values for velocity and acceleration within intervals can differ from ideal values, leading to potential malfunctions and increased computation requirements.
Innovation Solution
A numerical control device that performs reverse interpolation to calculate optimal velocity curves, allowing the movement part to reach maximum velocity while minimizing computational load by reading and processing blocks sequentially, using look-ahead blocks to determine target velocities and interpolation points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the width of the interval is large, then the amount of calculation is reduced, but the movement time increases because the velocity does not reach the ideal velocity
Solution Approach 1:
The patent divides the movement path into multiple intervals and performs reverse interpolation in stages. Instead of calculating the entire velocity curve in one forward pass, the method segments the calculation into backward passes from the target block, allowing for more precise velocity determination at each segment while reducing the computational burden on any single interval.
Solution Approach 2:
The patent applies reverse interpolation by calculating the velocity curve from the target block backward toward the current block, rather than the conventional forward direction. This inversion allows the system to determine target velocities more accurately by working backward from known boundary conditions, thereby reducing movement time without requiring excessive calculation resources.
2Measurement precision
If the width of the interval is narrowed, then the difference between calculated permissible values and ideal permissible values is reduced, but the amount of calculation increases
Solution Approach 1:
The movement path is divided into multiple intervals, and reverse interpolation is performed sequentially through these segments. This segmentation allows the system to achieve high velocity precision at each interval boundary without requiring the entire path to be calculated with fine granularity simultaneously, thus managing computational load effectively.
Solution Approach 2:
The patent performs preliminary calculations of target velocities and interpolation points for look-ahead blocks before actual movement execution. By pre-calculating these parameters using reverse interpolation, the system ensures high precision velocity control is ready in advance, reducing the need for complex real-time computations during motion.
3Loss of time
If reverse interpolation is performed to calculate optimal velocity curves, then movement time is reduced, but the computational load increases
Solution Approach 1:
The reverse interpolation process is segmented into iterative steps that calculate velocity curves for individual blocks and look-ahead blocks separately. This segmentation allows the complex computation to be distributed across multiple simpler calculation stages, reducing movement time while managing computational complexity through systematic breakdown.
Solution Approach 2:
The patent performs reverse interpolation for a limited number of look-ahead blocks rather than the entire program. This partial action provides sufficient velocity optimization for upcoming movements without requiring excessive computation, achieving the benefit of reduced acceleration/deceleration time with moderate computational effort.
Data Source
Figure 1
Figure 2~3
Figure 4~6
AI summary
Provided are a numerical control device, a machine tool, a numerical control method, and a numerical control program which contribute in achieving an advantage that an increase in moving time of a moving part is suppressed while suppressing the amount of computation for calculating a speed curve prior to acceleration/deceleration processing. A CPU of this numerical control device reads the current block Nnow and a prefetch block and determines a target block Nd and a target speed Vd at a command point for the target block Nd. The CPU calculates a first rising speed V1 at the position where tip acceleration becomes zero from the current tip acceleration. The CPU calculates a reverse interpolation point Prev. Every time when the reverse interpolation point Prev is calculated, the CPU calculates a second rising speed V2 at the position where the tip acceleration becomes zero from the tip acceleration at the reverse interpolation point Prev.