Inductive Angle Sensor Self-Correction for Rotor Run-Out Errors
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Solution Overview
Problem
Inductive angular position sensors suffer from run-out errors due to lateral movement and tilt of the rotor, leading to inaccurate determination of angular position, particularly in systems like robotic arms.
Innovation Solution
A sensor subsystem with a combination of fine and coarse sensor signals, an interface circuit, and a lookup table to generate and correct for angular position errors by averaging and interpolating differences between absolute angle values, compensating for tilt and eccentricity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If inductive angular position sensors are used to detect rotation, then rotational position can be determined, but run-out errors due to lateral movement and tilt cause inaccurate angular position determination
Solution Approach 1:
The sensor system is divided into two independent sensor paths: a fine sensor for high-resolution angle measurement and a coarse sensor for robust position detection. Each sensor processes signals independently and generates its own absolute angle value, allowing the system to leverage the strengths of both sensors while compensating for their individual weaknesses through comparison and averaging of results.
Solution Approach 2:
The system continuously compares the absolute angle values from both sensors, calculates their difference, and uses this feedback to generate a corrected output angle value. This feedback mechanism allows real-time compensation for run-out errors, tilt, and eccentricity effects, maintaining measurement accuracy despite mechanical imperfections.
2Measurement precision
If a single sensor signal is used for angular measurement, then the system is simpler, but accuracy is reduced due to run-out errors and tilt
Solution Approach 1:
The measurement function is segmented between two sensors with different characteristics - a fine sensor for precision and a coarse sensor for robustness. This segmentation allows each sensor to be optimized for its specific role while the combined system achieves superior overall accuracy that neither sensor could achieve alone.
Solution Approach 2:
The system merges the outputs of two independent sensor paths by calculating absolute angle values from each, comparing them, and generating a corrected output. This combination leverages the complementary strengths of both sensors, achieving high accuracy while maintaining reasonable system complexity through efficient signal processing.
3Measurement precision
If the sensor operates without calibration, then the system is easier to operate, but angular position errors accumulate due to tilt and eccentricity variations
Solution Approach 1:
The system performs preliminary calibration by averaging multiple measurements to establish baseline characteristics of the sensor system under specific tilt and eccentricity conditions. This preliminary action stores correction data that compensates for run-out errors, allowing the sensor to maintain high accuracy during normal operation without requiring frequent recalibration.
Solution Approach 2:
The sensor subsystem performs self-calibration by continuously comparing measurements from both fine and coarse sensors, automatically detecting and compensating for tilt and eccentricity effects. This self-service capability eliminates the need for external calibration equipment or complex calibration procedures, maintaining high accuracy while simplifying operation.
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
The solution effectively reduces angular position errors by continuously calibrating and correcting for variations in tilt and eccentricity, enhancing the accuracy and reliability of inductive angular position sensors in robotic systems.
Implementation Method 1
an inductive angular position sensor that includes an excitation coil, a rotor coil, a first set of stator coils, and a second set of stator coils
Data Source
AI summary
A sensor subsystem is disclosed. The sensor subsystem includes a sensor coupled to an interface circuit. The sensor may generate a fine sensor signal and a coarse sensor signal based on a rotation of the sensor. The interface circuit may generate first and second absolute angle values based on the fine and coarse sensor signals, respectively. The interface circuit may additionally generate an output angle value using a difference between the first and second absolute angle values.