Electromagnetic Quasi-Zero Stiffness Sensor for Absolute Displacement
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Solution Overview
Problem
Existing displacement sensors face challenges in measuring absolute displacement with high precision and real-time performance, especially in severe working conditions, due to mechanical springs causing damping issues at ultralow frequencies and high costs of advanced technologies like inertial sensors, radar, or laser technologies.
Innovation Solution
A quasi-zero stiffness absolute displacement sensor based on electromagnetic positive stiffness, comprising an eddy current displacement sensor unit, negative stiffness unit, intermediate connector, positive stiffness unit, and bottom shell, where the electromagnetic positive and negative stiffness mechanisms are adjusted by changing coil and magnet geometric parameters and current magnitude to reduce overall system rigidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a mechanical spring is used as a positive stiffness mechanism in the traditional quasi-zero stiffness absolute displacement sensor, then the system can achieve quasi-zero stiffness, but the damping cannot be ignored at ultralow frequency which affects measurement accuracy
Solution Approach 1:
The patent replaces the mechanical spring-based positive stiffness mechanism with an electromagnetic positive stiffness mechanism. The electromagnetic mechanism uses electromagnetic forces between coils and permanent magnets to provide the positive stiffness, eliminating the mechanical contact and associated damping effects that plague ultralow frequency measurements. This substitution resolves the contradiction by maintaining quasi-zero stiffness while removing the harmful damping effect.
2Measurement precision
If advanced measurement technologies such as inertial sensors, radar or laser technologies are used, then absolute displacement measurement can be achieved, but the measurement technologies have the problems of low precision, poor real-time performance, high cost
Solution Approach 1:
The patent replaces complex advanced measurement technologies with a simplified electromagnetic-based absolute displacement measurement system. By using the electromagnetic positive stiffness mechanism combined with an eddy current displacement sensor, the system achieves high-precision absolute displacement measurement without requiring complex inertial sensors, radar, or laser technologies. The electromagnetic field serves as both the stiffness mechanism and the measurement reference, eliminating the need for external complex measurement systems.
3Measurement precision
If the magnitude of electromagnetic positive stiffness and electromagnetic negative stiffness are adjusted by changing geometric parameters and current magnitude, then the overall rigidity of the system is reduced to achieve quasi-zero stiffness, but the system complexity increases
Solution Approach 1:
The patent employs parameter changes to achieve quasi-zero stiffness by adjusting the geometric parameters of coils and permanent magnets, as well as the magnitude of coil current. This allows dynamic control of the electromagnetic positive and negative stiffness magnitudes to achieve the desired quasi-zero overall rigidity. The principle of parameter changes enables flexible adjustment of system stiffness without adding complex mechanical adjustment mechanisms.
Solution Approach 2:
The electromagnetic coils serve multiple functions: they generate the electromagnetic positive stiffness force, provide the electromagnetic negative stiffness force, and act as the actuator for adjusting the stiffness magnitude. This multi-functionality reduces system complexity by eliminating the need for separate adjustment mechanisms for each function.
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
This solution achieves reduced damping, prolonged system life, smaller size, and high measurement precision by eliminating nonlinearity and achieving quasi-zero stiffness, enabling accurate absolute displacement measurement.
Implementation Method 1
eddy current displacement sensor unit comprises a top shell, an eddy current sensor and a mass block
Implementation Method 2
a positive stiffness mechanism and a negative stiffness mechanism of the sensor are both of an electromagnetic type, and the magnitude of electromagnetic positive stiffness and the magnitude of electromagnetic negative stiffness are adjusted by changing the geometric parameters of coils and permanent magnets and the magnitude of coil current
Data Source
AI summary
Disclosed is a quasi-zero stiffness absolute displacement sensor based on electromagnetic positive stiffness, and relates to the technical field of vibration measurement. The quasi-zero stiffness absolute displacement sensor comprises an eddy current displacement sensor unit, a negative stiffness unit, an intermediate connector, a positive stiffness unit, a bottom shell and a motion axis. The damping of the mechanism can be effectively reduced, the service life of the system is prolonged, and the mechanism size is reduced. By adjusting the number of layers of permanent magnets and coils in the electromagnetic positive stiffness unit and the electromagnetic negative stiffness unit and controlling the magnitude of current in the coils, electromagnetic force between the permanent magnets and the electromagnetic coils can be changed, the magnitude of positive stiffness and the magnitude of negative stiffness are adjusted, and control over the stiffness of the whole system is achieved.