Inductive Position Sensor Fault Detection via Segmented Receiver Tracks
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Solution Overview
Problem
Existing inductive position sensors fail to meet high safety requirements, particularly in environments where human safety and machine part alignment are critical, as they often do not detect faults in receiver coils or evaluation electronics effectively.
Innovation Solution
The design incorporates a scanning printed circuit board with multiple receiver tracks and a dividing element, generating signals with phase shifts of 60° or 120°, allowing for the detection of relative movement and the generation of digital position values that can be compared for error detection, with an electronic circuit configured to produce three digital signals from which two position values are determined, and an averaging device to ensure reliability and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional inductive position sensors with receiver coils are used, then basic position measurement function is achieved, but safety requirements are not met due to inability to detect faults in receiver coils or evaluation electronics
Solution Approach 1:
The receiver track is divided into multiple independent receiver conductor tracks (at least three) arranged with specific phase shifts (60° or 120°). This segmentation allows individual fault detection of each receiver track by comparing position values derived from different track combinations, enabling safety verification without requiring a completely different sensor architecture.
Solution Approach 2:
The system continuously monitors position values from multiple receiver tracks and compares them to detect inconsistencies. When a fault is detected through comparison of position values derived from different receiver track combinations, the system can identify the faulty track and trigger appropriate safety responses, providing continuous feedback for safety assurance.
2Reliability
If multiple receiver tracks with specific phase shifts are implemented, then fault detection capability is improved, but device complexity increases
Solution Approach 1:
The system uses specific phase shift parameters (60° or 120°) between receiver conductor tracks to enable fault detection. By changing the phase relationship parameter rather than the fundamental sensor structure, the system achieves enhanced reliability through mathematical relationships in the position value calculations without requiring fundamentally different hardware architecture.
Solution Approach 2:
The multiple receiver conductor tracks serve dual purposes: they simultaneously provide redundant position measurement capability and enable fault detection through comparison. The same hardware structure used for position measurement is also used for safety verification, eliminating the need for separate safety monitoring hardware.
3Reliability
If position values from multiple receiver tracks are compared, then error detection is enabled, but evaluation electronics complexity increases
Solution Approach 1:
The system generates multiple copies of position values from the same physical measurement through different receiver track combinations. By creating redundant position value calculations from segmented receiver tracks and comparing these copies, the system enables error detection using software-based comparison logic rather than additional hardware monitoring circuits.
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
This configuration enhances safety by enabling reliable operation and fault detection, ensuring that errors in the position sensor are recognized, thereby preventing accidents and damage, and meeting higher safety standards.
Implementation Method 1
When a time-varying electrical excitation current is applied to the excitation coils, signals dependent on the angular position are generated in the receiver coils during the relative rotation between the rotor and stator
Data Source
Figure 1~2
Figure 3
Figure 4a~4d
AI summary
The invention relates to an inductive position sensor comprising an electronic circuit (3), which is designed in such a way that initially three digital signals (S3.51, S3.52, S3.53; S3.61, S3.62, S3.63) can be produced from the signals (S1.11, S1.12, S1.13; S1.21, S1.22, S1.23) detected by three receiver conductor paths (1.11, 1.12, 1.13; 1.21, 1.22, 1.23). It is also possible to determine at least two position values (P, 3.71, P3.72; P3.81, P3.82, P3.83) by combining the three digital signals (S3.51, S3.52, S3.53; S3.61, S3.62, S3.63), and said position values (P, P3.71, P3.72; P3.81, P3.82, P3.83) can be guided to a comparator (3.20, 4.1). The invention also relates to a method for operating an inductive position sensor, to a measuring system which comprises, in addition to the position sensor, a data interface (5.20, 4.20) and subsequent electronics (4) which comprise the comparator (4.1).