Robotic Arm Vibration Analysis for Task-Aware Fault Detection

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Solution Overview

Problem

Existing methods for predictive maintenance in robotic arms using vibration measurements are prone to false alarms and miss important failures due to noisy and complex non-stationary signals, and fail to account for dynamic operating conditions and varying tasks.

Innovation Solution

A method involving feature extraction to calculate similarity coefficients between vibration sensor data and templates, followed by time-frequency decomposition and similarity estimation to generate comprehensive anomaly scores, which are input into a predictive maintenance model for fault detection, failure prediction, and remaining useful life estimation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If time-frequency decomposition and similarity estimation are used to analyze non-stationary vibration signals, then measurement precision and reliability of fault detection are improved, but device complexity and computational requirements increase

Engineering Contradiction:
Improvefault detection accuracyVSAvoidsignal processing complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The vibration signal is divided into multiple segments using time-frequency decomposition (e.g., wavelet transform or short-time Fourier transform). Each segment is analyzed separately to extract local features, which are then combined to form comprehensive fault indicators. This segmentation approach enables precise detection of transient faults in non-stationary signals while managing computational complexity through localized analysis.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The analysis transitions from traditional time-domain or frequency-domain single-dimensional analysis to time-frequency domain two-dimensional analysis. By representing signals in the time-frequency plane, the method captures both temporal and spectral characteristics simultaneously, improving fault detection precision for non-stationary vibration signals without requiring excessive computational resources.

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

2Adaptability or versatility

If comprehensive feature extraction and similarity coefficients are calculated for multiple tasks, then adaptability to varying operating conditions is improved, but loss of time and computational overhead increase

Engineering Contradiction:
Improveadaptability to dynamic conditionsVSAvoidprocessing time
Core Design Contradiction:
Adaptability or versatilityVSLoss of time

Solution Approach 1:

Task-specific vibration templates are pre-computed and stored during system initialization or offline calibration phases. During online operation, the system compares real-time vibration signals against these pre-established templates using similarity coefficients, avoiding the need to perform comprehensive feature extraction for each task during runtime. This preliminary action significantly reduces processing time while maintaining high adaptability to varying operating conditions.

Inventive Principle:
Principle #10Preliminary action

3Device complexity

If traditional vibration analysis methods are used for robotic arms, then device complexity is reduced, but measurement precision and reliability deteriorate due to non-stationary signals and false alarms

Engineering Contradiction:
Improveanalysis method simplicityVSAvoidpredictive maintenance reliability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The system introduces task-specific vibration templates as intermediaries between the raw vibration signals and the fault detection algorithm. These templates represent normal vibration patterns for different robotic arm tasks and serve as reference standards. By comparing actual signals against these intermediary templates using similarity coefficients, the system achieves reliable fault detection without requiring overly complex analysis methods, as the templates capture task-specific characteristics that simplify the detection process.

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentUS11215535B2Predictive maintenance for robotic arms using vibration measurements
Publication Date: 2022.01.04 HITACHI LTD
  • US11215535B2 patent drawing
  • US11215535B2 patent drawing
  • US11215535B2 patent drawing

AI summary

Example implementations described herein involve systems and methods for conducting feature extraction on a plurality of templates associated with vibration sensor data for a moving equipment configured to conduct a plurality of tasks, to generate a predictive maintenance model for the plurality of tasks, the predictive maintenance model configured to provide one or more of fault detection, failure prediction, and remaining useful life (RUL) estimation.