Position Detection Apparatus for Simultaneous Absolute and Relative Positioning
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Solution Overview
Problem
Vernier type absolute encoders cannot simultaneously derive absolute and relative positions due to the need to switch signals, which disrupts the relative position derivation process when acquiring multiple periodic signals for absolute position determination.
Innovation Solution
A position detection apparatus that outputs multiple displacement signals with different periods, allowing simultaneous derivation of absolute and relative positions by switching among these signals, enabling continuous relative position detection during absolute position acquisition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the signal output unit switches among multiple periodic signals to acquire signals for deriving absolute position, then the absolute position can be derived accurately, but the relative position deriving process is interrupted and cannot detect positional changes during switching
Solution Approach 1:
The patent segments the signal output into three distinct phases: first signal output phase, second signal output phase, and first signal output phase again. This segmentation allows the system to acquire multiple periodic signals for absolute position derivation while simultaneously maintaining continuous relative position detection through the second signal, thus resolving the contradiction between accurate absolute position detection and continuous relative position monitoring.
2Productivity
If only one periodic signal is used to derive relative position, then the relative position can be detected continuously, but multiple periodic signals cannot be acquired for accurate absolute position derivation
Solution Approach 1:
The patent implements multi-functionality by having the signal output unit output multiple types of signals (first signal and second signal with different periods) in a cyclic manner. The first signal serves both for absolute position derivation and relative position detection, while the second signal primarily serves relative position detection. This universal signal output mechanism enables the system to achieve both continuous relative position detection and accurate absolute position derivation simultaneously.
3Measurement precision
If multiple periodic signals are acquired by switching signals for absolute position derivation, then the absolute position accuracy is improved, but the circuit complexity and processing time increase
Solution Approach 1:
The patent ensures continuity of useful action by designing a cyclic signal output pattern where the first signal and second signal are output in sequence without interruption. This continuous signal output enables the position deriver to simultaneously perform absolute position derivation using multiple signals and relative position detection using the second signal, thereby improving position detection accuracy without significantly increasing circuit complexity or processing time.
Data Source
AI summary
A position detector of a mover relative to a stator includes: an output unit outputting displacement signals including a first signal in a first period and a second signal in a period longer than the first period, while switching among the displacement signals, according to a change in the position of the mover; and a deriver that derives an absolute position as the position of the mover based on the displacement signals, and derives a relative position as a displacement amount with respect to a predetermined absolute position of the mover, wherein in deriving the absolute position, the signal output unit outputs the first signal, the second signals, and the first signal in this order, and the deriver derives the absolute position based on the displacement signals, in deriving the relative position, the position deriver derives the relative position based on the first signal and the second signals.