Gear Sensor Calibration for High-Accuracy Electrical Drives
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Solution Overview
Problem
Existing electrical drive systems face challenges in achieving high positional accuracy due to errors in sensor signal mapping and calibration, particularly when multiple error sources have the same frequency, making it difficult to distinguish and mitigate these errors.
Innovation Solution
The method involves rotating the gear, mapping and filtering sensor signals using the gear ratio, transforming differences into the frequency domain, and calibrating the second sensor signal based on the error component in the frequency domain to correct positioning errors, while ensuring constant speed and load during data recording to prevent vibration modes and oversample lower frequency contributions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sensor signals are mapped and calibrated using traditional time-domain filtering methods, then the calibration process is simple and fast, but positioning accuracy deteriorates when multiple error sources have the same frequency
Solution Approach 1:
The patent transforms the calibration problem from the time domain to the frequency domain using Fourier transform. This dimensional change allows differentiation of error sources that have the same frequency in the time domain but different characteristics in the frequency domain, thereby improving positioning accuracy without significantly increasing calibration complexity
Solution Approach 2:
The patent changes the representation parameters of sensor signals from time-domain values to frequency-domain spectral components. By analyzing errors in the frequency domain and assigning them to specific error sources based on their spectral characteristics, the system achieves better separation and correction of multiple error sources with the same frequency
2Adaptability or versatility
If multiple error sources with the same frequency are present, then the system can handle complex operating conditions, but error source differentiation becomes difficult
Solution Approach 1:
By transforming sensor signals and error analysis from the time domain to the frequency domain, the patent enables differentiation of multiple error sources that share the same frequency. In the frequency domain, errors can be separated based on their spectral characteristics and phase relationships, making identification feasible even when time-domain signals overlap
Solution Approach 2:
The patent introduces the frequency domain as an intermediary representation space between the raw sensor signals and the error source identification process. This intermediary domain provides additional discriminatory power for separating error sources that are indistinguishable in the time domain
Data Source
Figure 1~2
AI summary
Method of operating an electrical drive system (100), the electrical drive system (100) comprising: - a, in particular mechanical, gear (1) having an input shaft (2) and having an output shaft (3), wherein the gear (1) has a known gear ratio between the input shaft (2) and the output shaft (3), - a first sensor (4) being coupled to the input shaft (2) of the gear (1) and generating a first sensor signal (S1), the first sensor signal (S1) depending on a rotational angle of the input shaft (2), and - a second sensor (5) being coupled to the output shaft (3) of the gear (1) and generating a second sensor signal (S2), the second sensor signal (S2) depending on a rotational angle of the output shaft (3), the method comprising the steps: - rotating the gear (1), in particular at least over a full rotation of the output shaft (3), - mapping the first sensor signal (S1) to the second sensor signal (S2) using the gear ratio, - calculating a difference (e(t)) between the mapped first and second sensor signals (S1, S2), - filtering the calculated difference (e(t)), and - calibrating the second sensor signal (S2) depending on the filtered calculated difference.