Machine Learning Servo Gain Optimization for CNC Control

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Solution Overview

Problem

Optimizing servo gain in machine control systems is challenging due to varying machine conditions and priority factors, making it difficult to estimate and adjust gains effectively for machining accuracy, productivity, and energy efficiency.

Innovation Solution

A machine learning device is integrated into a control system to perform reinforcement learning, using state observation, reward calculation, and decision-making to automatically adjust servo gains based on machine-specific data and priority factors, allowing for real-time optimization and sharing of value functions across machines.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If servo gain is adjusted manually on a case-by-case basis using an adjustment tool, then the servo gain can be optimized for specific machining conditions, but the optimization process requires significant time and manual effort

Engineering Contradiction:
Improveservo gain optimization accuracyVSAvoidtime for gain adjustment
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The control apparatus automatically performs servo gain optimization by itself without requiring manual intervention. The optimization unit acquires machining information, determines priority factors, and calculates optimal gain values automatically, enabling the system to serve itself in the gain adjustment process.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent replaces the manual mechanical adjustment process with an automated information processing system. Instead of manually using adjustment tools, the system uses a control apparatus that processes machining information and automatically determines optimal servo gain values through computational methods.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If servo gain is adjusted separately for each machine and condition, then the gain can be optimized for specific machine characteristics, but the complexity of managing multiple gain settings increases

Engineering Contradiction:
Improvegain optimization for specific conditionsVSAvoidcomplexity of gain management
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The control apparatus serves multiple machines and handles various machining conditions through a single unified system. The optimization unit can process different types of machining information and adapt to different priority factors, making the system universal across multiple machines and applications.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system dynamically changes servo gain parameters based on machining conditions and priority factors. Instead of maintaining fixed separate settings, the optimization unit calculates and adjusts gain values according to current operational parameters, enabling adaptive optimization without manual reconfiguration.

Inventive Principle:
Principle #35Parameter changes

3Manufacturing precision

If servo gain is adjusted to prioritize machining accuracy, then the machining quality improves, but the productivity and cycle time may be reduced

Engineering Contradiction:
Improvemachining accuracyVSAvoidmachining speed
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The system dynamically adjusts servo gain based on real-time machining conditions and priority factors. Instead of using fixed conservative settings, the optimization unit can increase gain when conditions allow for faster operation, and decrease it when precision is critical, enabling the system to adapt its performance characteristics dynamically.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The control apparatus uses feedback from machining information to optimize servo gain. By analyzing actual machining results and conditions, the system can determine the appropriate balance between speed and accuracy, adjusting gain values to achieve optimal performance based on observed outcomes rather than predetermined settings.

Inventive Principle:
Principle #23Feedback

4Adaptability or versatility

If multiple value functions are stored for different priority factors, then the system can selectively optimize for different goals, but the memory requirements and system complexity increase

Engineering Contradiction:
Improveability to optimize for different priority factorsVSAvoidmemory storage requirements
Core Design Contradiction:
Adaptability or versatilityVSQuantity of substance

Solution Approach 1:

Instead of storing complete separate value functions for different priority factors, the system changes the parameters and weighting within a unified value function based on the current priority factor. The optimization unit adjusts the importance of different terms in the value function according to whether accuracy, speed, or energy efficiency is the current priority, avoiding the need to store multiple complete functions.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentUS10564611B2Control system and machine learning device
Publication Date: 2020.02.18 FANUC LTD
  • US10564611B2 patent drawing
  • US10564611B2 patent drawing
  • US10564611B2 patent drawing

AI summary

Provided are a controller and a machine learning device that perform machine learning to optimize the servo gain of a machine inside a facility in accordance with action conditions, action environments, and a priority factor of the machine. The control system observes machine information on a machine as state, acquires information on machining by a machine as determination data, calculates a reward based on the determination data and reward conditions, performs the machine learning of the adjustment of the servo gain of the machine, determines an action of adjustment of the servo gain of the machine based on the state data and a machine learning result of the adjustment of the servo gain of the machine, and changes the servo gain of the machine, based on the action of adjustment of the determined servo gain.