Absolute Position Detector Abnormality Detection
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Solution Overview
Problem
Conventional absolute position detectors in machine tools face errors due to temperature drift and electromagnetic noise, leading to false abnormality alarms as they cannot distinguish between actual abnormalities and noise-induced errors, resulting in increased manufacturing costs and power consumption.
Innovation Solution
An absolute position detector that calculates a relative error between high-resolution and absolute position sensor outputs, using a clock switching unit to switch between high-speed and low-speed clocks based on abnormality detection signals, ensuring abnormality detection only when the state persists beyond noise generation periods, minimizing power consumption and avoiding noise interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If continuous abnormality detection is performed at high speed, then detection accuracy is improved, but power consumption increases
Solution Approach 1:
The patent implements periodic abnormality detection by switching between high-speed detection mode (during noise-free periods) and low-speed detection mode (during noise generation periods). The detection frequency is dynamically adjusted based on the operational state, performing detailed checks only when conditions permit, thereby reducing overall power consumption while maintaining detection accuracy when needed.
Solution Approach 2:
The detection speed is made dynamic rather than static. The system automatically transitions between high-speed and low-speed detection modes based on real-time conditions, optimizing the balance between detection accuracy and power consumption by adapting the detection rate to the current operational context.
2Reliability
If abnormality detection is performed continuously, then reliability is improved, but false alarms increase due to noise interference
Solution Approach 1:
The patent extracts and identifies noise generation periods from the overall operation cycle, then excludes these periods from abnormality detection evaluations. By separating noise-prone intervals from clean intervals, the system performs abnormality checks only during noise-free periods, eliminating false alarms caused by electromagnetic interference while maintaining continuous monitoring capability.
Solution Approach 2:
The patent introduces an intermediary mechanism (noise period identification and clock switching logic) that mediates between continuous monitoring requirements and noise interference. This intermediary layer filters out noise-corrupted detection windows and redirects detection activities to clean periods, ensuring reliable abnormality detection without false positives.
3Measurement precision
If high-resolution position detection is used, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent segments the position detection function into two distinct components: a high-resolution detector for precise measurements and an absolute position detector for coarse but robust positioning. By dividing the detection system into specialized segments rather than using a single complex high-resolution system throughout, the overall device complexity is reduced while maintaining high measurement precision where needed.
Data Source
AI summary
In an absolute position detector, a relative error calculation circuit calculates, at times indicated by a clock signal C1, a relative error E between an output θ2 from an absolute position detection sensor and a position output θ1 from a high-resolution position detection sensor. An abnormality judgment unit judges whether the relative error E exceeds a preset abnormality judgment value. A clock switching unit outputs, as the clock signal, a high-speed clock CH having a period shorter than a noise generation period when the relative error E is judged as exceeding the preset abnormality judgment value, and outputs a slow-speed clock CL in other cases. A counter measures, based on the clock signal C1, a duration in which the abnormality detection signal AF is maintained HI, and outputs an alarm when the duration exceeds the noise generation period.