NC Machine Tool Look-Ahead for Conditional Branch Motion Profiles

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Solution Overview

Problem

Real-time numerically controlled production systems face delays due to forced synchronization when dealing with conditional program branches, as they can only calculate the future up to the decision time of the next condition, leading to increased processing time and potential delays.

Innovation Solution

Implementing a look-ahead module that pre-calculates and stores alternative movement profiles for each alternative control program section, allowing for parallel calculation of possible movement profiles, eliminating the need for forced synchronization and reducing processing delays.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If forced synchronization is implemented at conditional program branches, then real-time control accuracy is maintained, but processing time increases and productivity decreases

Engineering Contradiction:
Improvereal-time control accuracyVSAvoidprocessing speed
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The look-ahead module pre-calculates alternative movement profiles for all possible program branches before the condition is evaluated. By preparing multiple future trajectories in advance (parallel calculation), the system eliminates the need for forced synchronization delays, as the correct profile is already ready when the condition outcome is known.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system dynamically adapts by calculating different movement profiles based on potential condition outcomes. Instead of a static single-path calculation, the controller maintains multiple dynamic alternatives ready for selection, allowing optimal performance regardless of which branch is taken.

Inventive Principle:
Principle #15Dynamics

2Adaptability or versatility

If multiple alternative control program sections are provided, then program versatility and adaptability are improved, but processing time increases due to sequential calculation

Engineering Contradiction:
Improveprogram branching capabilityVSAvoidprogram processing time
Core Design Contradiction:
Adaptability or versatilityVSLoss of time

Solution Approach 1:

The look-ahead module performs preliminary calculation of movement profiles for all alternative program sections in parallel before the condition is evaluated. This pre-computation eliminates sequential processing delays, as all alternative trajectories are prepared in advance and the correct one is simply selected based on the condition outcome.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system transitions from sequential single-path processing to parallel multi-path calculation by adding a temporal dimension - calculating multiple future trajectories simultaneously in the look-ahead buffer rather than sequentially during execution.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Manufacturing precision

If the look-ahead buffer size is increased, then movement profile calculation accuracy is improved, but memory requirements and system complexity increase

Engineering Contradiction:
Improvemovement profile accuracyVSAvoidbuffer memory requirements
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The system calculates movement profiles for a limited number of ahead blocks (e.g., 10-50 blocks) rather than the entire program. This partial look-ahead provides sufficient accuracy for most practical applications while constraining memory requirements and computational complexity to manageable levels.

Inventive Principle:
Principle #16Partial or excessive action

Solution Approach 2:

By pre-calculating only the necessary look-ahead distance required for smooth motion control, the system achieves adequate movement profile accuracy without over-provisioning buffer memory, balancing precision requirements with system complexity.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP3658996B1Production system and method for operating a numerically controlled production system
Publication Date: 2021.09.01 SIEMENS AG
  • EP3658996B1 patent drawingFigure 1
  • EP3658996B1 patent drawingFigure 2
  • EP3658996B1 patent drawingFigure 3~4

AI summary

The invention relates to a numerically controlled production system, in particular a machine tool (2), which is connected to a numerical controller (4). A control program with successive program sets is provided in the numerical controller (4), and the numerical controller (4) comprises a look-ahead module (24) which determines a movement profile (50) for at least one movement axis (16) from multiple successive control program sets (31) prior to a movement, said movement profile comprising guidance variables for a travel/time movement for the at least one movement axis (16) for successive clock time points. The control program comprises at least one program branching (32, 40) which is controlled by a condition and which comprises multiple successive alternative control program sections (34, 36, 38), said program branching determining which of the alternative control program sections (34, 36, 38) is additionally ran depending on the condition. The look-ahead module (24) calculates an alternative movement profile (52, 54, 56) for each alternative control program section (34, 36, 38) prior to an additional movement, stores same, and holds same ready for the required program branching (32, 40) in order to carry out the additional movement.