Absolute Displacement Sensor Feedback Control for Low-Frequency Detection
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Solution Overview
Problem
Conventional displacement sensors face difficulties in detecting absolute displacement and velocity in structures with low natural frequencies, as they become large and structurally fragile when attempting to lower their natural frequency, and require complex adjustments to maintain stability at extremely low frequencies.
Innovation Solution
An absolute displacement detection method that involves detecting relative velocity and controlling the mass body's displacement through positive and negative feedback of relative displacement and acceleration, combined with phase lag compensation to lower the natural frequency and expand the detectable range without structural defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the mass of the mass body is made large and supported with low rigidity to lower the natural frequency, then the detectable range is expanded, but the sensor becomes large in size and structurally fragile
Solution Approach 1:
The patent changes the dynamic parameters of the system by introducing feedback control that modifies the effective natural frequency and damping characteristics. Through feedback control, the system achieves low-frequency detection capability without physically increasing the mass body size or reducing structural rigidity, thereby resolving the contradiction between expandable detection range and structural strength.
2Measurement precision
If positive feedback is applied to expand detection to extremely low frequencies, then the detectable range is enlarged, but the sensor becomes difficult to adjust and prone to control instability
Solution Approach 1:
The patent employs feedback control to achieve low-frequency detection without the instability issues of positive feedback. By using feedback mechanisms that monitor and adjust the mass body's displacement, velocity, and acceleration, the system expands its detectable frequency range to extremely low frequencies while maintaining control stability and reducing adjustment complexity through automated control algorithms.
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
Enables stable detection of absolute displacement across a wide range of frequencies, including low frequencies, without requiring complex adjustments, and allows for the detection of both high and low natural frequency structures with large and small amplitudes, while maintaining sensor stability and miniaturization.
Implementation Method 1
a detection means (4) which detects a relative velocity of the detection object with respect to the mass body (3)
Data Source
AI summary
An absolute displacement sensor 1 includes a sensor housing 2 serving as a detection object; a mass body 3 having a mass m which is movably supported by the sensor housing 2 with a spring coefficient k and a damping coefficient c; a detecting means 4 which electrically detects a relative velocity of the sensor housing 2 with respect to the mass body 3; a feedback control means 5 which controls the absolute displacement of the mass body 3 attributable to the absolute displacement of the sensor housing 2 by positively feeding back the relative displacement and by negatively feeding back a relative acceleration obtained by primarily differentiating the relative velocity, respectively; and a phase lag compensation means 6 which performs phase lag compensation with respect to the relative displacement.