Resolver Inductive Coupling Monitoring for Early Defect Detection
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Solution Overview
Problem
Existing resolver systems in articulated robot arms suffer from precision errors and safety risks due to gradual degradation of wire isolation, which is not detected until close to failure, leading to inaccurate position measurements and potential safety hazards.
Innovation Solution
A method for monitoring resolvers by obtaining a master sample of inductive coupling and periodically updating it, using low-pass filtering to adapt to slow changes, and setting thresholds to detect deviations from acceptable ranges, ensuring early detection of defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a wide threshold for inductive coupling variation is used to avoid false failure detection, then reliability is improved, but measurement precision deteriorates
Solution Approach 1:
The patent stores a master sample of inductive coupling characteristics obtained during normal operation before any failure occurs. This preliminary action creates a reference baseline that enables precise failure detection without requiring wide thresholds, thereby resolving the contradiction between reliability and precision.
Solution Approach 2:
The system continuously compares current inductive coupling measurements against the stored master sample and triggers a failure indication when deviations exceed a threshold. This feedback mechanism enables reliable failure detection while maintaining precision by using operation-specific baseline data rather than generic thresholds.
2Device complexity
If total inductive coupling is used for failure detection, then device complexity is reduced, but measurement precision deteriorates due to orientation-dependent variations
Solution Approach 1:
The system uses the resolver's own inductive coupling characteristics during normal operation to create its own failure detection reference. By storing a master sample from actual operation, the system eliminates the need for external calibration equipment or complex reference systems, achieving simple yet precise failure detection.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enhances precision and safety by reliably detecting resolver failures before they cause significant position errors, reducing the risk of accidents and maintaining accurate robot operation.
Implementation Method 1
a resolver comprises first and second winding assemblies, which are rotatable with respect to each other and are inductively coupled so that when a current is flowing in one of the assemblies, a voltage will be induced in the other
Data Source
Figure 1~2
Figure 3~4
AI summary
A resolver (8) comprises first and second winding assemblies (14, 15) which are rotatable with respect to each other and are inductively coupled, the first winding assembly (14) having a sine winding (14s) and a cosine winding (14c) arranged so that when inductive coupling between the sine winding (14s) and the second winding assembly (15) is zero, inductive coupling between the cosine winding (14c) and the second winding assembly (15) is at a maximum, and when inductive coupling between the cosine winding (14c) and the second winding assembly (15) is zero, inductive coupling between the sine winding (14s) and the second winding assembly (15) is at a maximum. A method for monitoring the resolver (8) comprises the steps of a) obtaining (S6, S10) a master amount (MA) of total inductive coupling between the first and second winding assemblies (14, 15) of said resolver (8), b) obtaining (S2) a current amount (|Ur|, Σ) of total inductive coupling at a current instant in time, c) deciding (S8) that the resolver (8) is defective if a difference between the current amount (|Ur|, Σ)and the master amount (MA) exceeds a predetermined threshold (Thr1).