Position Detection Apparatus Using LC Circuit Segmentation
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Solution Overview
Problem
Conventional position detection apparatuses face challenges in achieving high resolution and accuracy, especially for long-distance position detection, due to limitations in frequency change and measurement accuracy.
Innovation Solution
The position detection apparatus includes a moving body with detection object portions, relative displacement detection parts with LC circuits, and a position calculation part that processes output signals to calculate displacement. This apparatus selectively uses changes in oscillation frequency from peak-to-peak sections to achieve high-resolution position detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the coil length is increased to detect position over long distance, then the detection range is improved, but the frequency change (Δf) decreases leading to lower position detection resolution
Solution Approach 1:
The patent divides the detection system into multiple relative displacement detection parts arranged along the moving direction, each detecting local displacement with high resolution. The position calculation part integrates signals from multiple segments to achieve both long-range detection and high resolution, resolving the contradiction between coil length and frequency change.
Solution Approach 2:
The patent transitions from single-coil inductance measurement to multi-coil oscillation frequency measurement. By using multiple LC circuits arranged in the moving direction and measuring their oscillation frequencies simultaneously, the system achieves high-resolution position detection over long distances, overcoming the limitation of single-coil systems where increasing length reduces frequency change.
2Length of stationary object
If the oscillation frequency is measured at peak sections, then the measurement range is improved, but the position detection accuracy deteriorates due to small frequency change in proportion to position change
Solution Approach 1:
The patent applies different processing strategies to different sections of the oscillation frequency signal. It identifies peak sections and peak-to-peak sections, and selectively uses frequency changes from peak-to-peak sections for position calculation. This local differentiation ensures high accuracy where frequency change is significant while maintaining broad detection coverage.
Solution Approach 2:
The patent changes the parameter selection criterion from using all oscillation frequency data to selectively using frequency change data from peak-to-peak sections. This parameter change optimizes the signal processing to focus on regions where frequency change is most sensitive to position changes, thereby improving accuracy without sacrificing detection range.
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 apparatus enables high-accuracy and high-resolution position detection over long distances by effectively utilizing changes in oscillation frequency, particularly in peak-to-peak sections, thereby overcoming the limitations of conventional systems.
Implementation Method 1
each of the relative displacement detection parts including a winding coil for forming an LC circuit and a capacitor connected between opposite end portions of the winding coil
Implementation Method 2
The position detector makes use of a phenomenon in which the inductance of the coil is changed by an induced current that is generated in the shaft-like moving body due to the positional relationship between the coil and the shaft-like moving body, which is a conductor
Data Source
AI summary
AimTo provide a position detection apparatus capable of detecting a position with a high accuracy and a high resolution.SolutionIncluded are: a moving body 13 having an elongated shape, disposed so as to be movable in its longitudinal direction, and having plural detection object portions 15a, 15b, 15c, 15d disposed along the longitudinal direction, the plural detection object portions 15a, 15b, 15c, and 15d having a conductivity; a first detection part 20 and a second detection part 25 arranged along a moving direction of the moving body 13, and disposed so as to be capable of facing the respective detection object portions 15a, 15b, 15c, 15d of the moving body 13 with a predetermined interval therebetween; and a displacement detection parts 40, 41 for detecting a displacement of the moving body 13 by processing output signals from the first detection part 20 and the second detection part 25. The first detection part 20 and the second detection part 25 each include a winding coil 21, 26 for forming an LC circuit and a capacitor 22, 27 connected between opposite end portions of the winding coil 21, 26.