Numerical Control Parameter Auto-Tuning for Machine Tools

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Solution Overview

Problem

Existing numerical control methods for machine tools require frequent adjustments of feedback compensators and lack automated setting of acceleration/deceleration parameters, leading to inefficiencies and low reliability in abnormality detection.

Innovation Solution

The method employs closed loop transfer functions and modeling errors to automatically determine optimal control parameters, including feed forward and feedback gains, and sets suitable acceleration/deceleration parameters, enabling quick and reliable judgment of abnormalities.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If feedback compensator adjustment is performed manually based on time response and ideal response error, then control precision can be improved, but adjustment time and operator load increase significantly

Engineering Contradiction:
Improvecontrol precisionVSAvoidadjustment time
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

The system automatically determines control parameters by itself without operator intervention. The parameter determination unit automatically calculates optimal control parameters based on measured plant transfer functions, eliminating the need for manual adjustment by operators while maintaining high control precision.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

Manual mechanical adjustment of feedback compensators is replaced by an automated computational system. The parameter determination unit uses computer-based calculations to determine control parameters, substituting the manual mechanical tuning process with an automated electronic system that rapidly computes optimal values.

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

2Reliability

If multiple control parameters are manually adjusted, then system performance can be optimized, but the complexity of operation and time required increase

Engineering Contradiction:
Improvesystem performanceVSAvoidoperation complexity
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The system autonomously determines multiple control parameters including feedforward gain, feedback gain, and acceleration/deceleration parameters without requiring operator expertise or manual adjustment. The parameter determination unit automatically calculates all necessary parameters based on system measurements, making the complex multi-parameter optimization process transparent and simple to operate.

Inventive Principle:
Principle #25Self-service

3Manufacturing precision

If acceleration and deceleration parameters are manually set, then machining precision can be maintained, but productivity decreases due to conservative parameter settings

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

Solution Approach 1:

The system dynamically determines acceleration and deceleration parameters based on actual system characteristics measured during operation. Instead of using fixed conservative values, the parameters are adapted to the specific machine tool configuration and load conditions, enabling optimal balance between machining precision and productivity for each operating condition.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system changes acceleration and deceleration parameters automatically based on measured plant transfer functions and control parameter calculations. The parameter determination unit computes optimal acceleration/deceleration values that match the actual system dynamics, allowing parameters to be adjusted according to specific machining conditions rather than using fixed conservative settings.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP2634657B1Numerical control method
Publication Date: 2020.07.01 MAKINO MILLING MASCH CO LTD
  • EP2634657B1 patent drawingFigure 1
  • EP2634657B1 patent drawingFigure 2
  • EP2634657B1 patent drawingFigure 3

AI summary

In this numerical control method that drives the feed shaft of a machine tool (10) by means of a servo control unit (52), a transmission function is determined by modeling the operation of the servo control unit (52) of the feed shaft, the closed loop transmission function (GBP) of the position loop and/or the closed loop transmission function of the velocity loop of the servo control unit (52) of the machine tool is measured using the frequency response of the feed shaft, the control subject (PP) of the position loop and/or the control subject of the velocity loop is determined using the measured closed loop transmission function, the position loop modeling error (ΔPP) and/or the velocity loop modeling error is determined from the control subject, and at least one control parameter of the servo control unit (52) is calculated using the closed loop transmission function and/or the modeling error. As a result, the optimum plurality of control parameters corresponding to the state of the feed shaft is determined easily and automatically.