Worm Gear Machine Critical Error Identification and Iterative Compensation

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Solution Overview

Problem

Current methods lack systematic modeling and compensation for comprehensive geometric errors in worm gear machines, leading to inadequate machining accuracy due to the coupling effects of multiple error elements, with no effective methods for identifying critical errors.

Innovation Solution

A method using a random forest algorithm to establish a pose error relation between the worm gear hob and worm gear, identifying critical errors, and iteratively compensating them by simplifying the geometric error-pose error model, improving machining accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If comprehensive geometric errors of multiple motion axes are considered in the error model, then the machining accuracy can be improved, but the device complexity and computational burden increase significantly

Engineering Contradiction:
Improvemachining accuracyVSAvoiderror model complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent segments the comprehensive geometric errors into two categories: position-dependent geometric errors (PDGEs) and position-independent geometric errors (PIGEs). This segmentation allows the error model to be divided into manageable components, where PDGEs vary with motion position and PIGEs remain constant. By treating these error types separately, the complex error modeling problem becomes more tractable while still achieving comprehensive error compensation for high machining accuracy.

Inventive Principle:
Principle #1Segmentation

2Manufacturing precision

If all geometric error elements are compensated simultaneously, then the machining accuracy improves, but the difficulty of detecting and measuring increases

Engineering Contradiction:
Improvemachining accuracyVSAvoiderror identification difficulty
Core Design Contradiction:
Manufacturing precisionVSDifficulty of detecting and measuring

Solution Approach 1:

The patent employs a feedback mechanism through the random forest algorithm that processes measured geometric error data and provides importance coefficients for each error element. The system measures all geometric error elements, feeds this data into the random forest model, and receives feedback in the form of identified critical errors. This feedback loop enables the system to automatically prioritize which errors have the greatest impact on machining accuracy, making the detection and measurement process more efficient while maintaining comprehensive error compensation.

Inventive Principle:
Principle #23Feedback

3Manufacturing precision

If a comprehensive error model considering multiple geometric error elements is established, then the machining accuracy can be improved, but the loss of time for error analysis and compensation increases

Engineering Contradiction:
Improvemachining accuracyVSAvoiderror analysis time
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

The patent applies partial action by using the random forest algorithm to identify only the critical geometric error elements that have the most significant impact on machining accuracy, rather than analyzing and compensating for all geometric error elements equally. By focusing computational resources on the most important error sources (approximately 20% of error elements that contribute to 80% of the total error), the system achieves comprehensive error compensation效果 while significantly reducing the time required for error analysis and compensation.

Inventive Principle:
Principle #16Partial or excessive action

Data Source

PatentUS12066809B2Method for identifying critical error of worm gear machine and method for iteratively compensating critical error of worm gear machine
Publication Date: 2024.08.20 CHONGQING UNIV
  • US12066809B2 patent drawing
  • US12066809B2 patent drawing
  • US12066809B2 patent drawing

AI summary

A method for identifying a critical error of a worm gear machine, step 1: obtaining an actual forward kinematic model T27a and an ideal forward kinematic model T27i from a coordinate system of a worm gear hob to a coordinate system of a worm gear, thereby establishing a geometric error-pose error model of the worm gear machine; step 2: regarding the geometric error-pose error model of the worm gear machine as a multi-input multi-output (MIMO) nonlinear system, and solving, by taking the geometric error of each motion axis of the worm gear machine as an input feature X, and a pose error between the worm gear hob and the worm gear as an output variable Y, an importance coefficient of each input feature with a random forest algorithm; and step 3: determining a critical error affecting a machining accuracy of the worm gear machine.