Magnetic Disk Negative Stiffness Actuator with Linear Force Control
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Solution Overview
Problem
Quasi-zero stiffness vibration isolation systems face challenges with non-linear electromagnetic forces leading to multi-stable phenomena and complex dynamic behaviors, such as jumping, due to the inherent non-linearity of the negative stiffness actuator, which complicates control and vibration reduction.
Innovation Solution
A linear control method for electromagnetic force-displacement is introduced for a magnetic disk type negative stiffness electromagnetic actuator, where the current is used as an input control variable to establish a linear relationship between electromagnetic force and displacement, thereby managing the negative stiffness to achieve constant ideal negative stiffness, simplifying the control system and avoiding complex sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a negative stiffness actuator is used to achieve quasi-zero stiffness vibration isolation, then the vibration isolation frequency band is broadened and low-frequency vibration isolation is improved, but the electromagnetic force exhibits significant non-linear characteristics with displacement, causing multi-stable phenomena and complex dynamic behaviors
Solution Approach 1:
The patent applies parameter changes by transforming the non-linear electromagnetic force-displacement relationship into a linear relationship through mathematical modeling and parameter optimization. The electromagnetic force expression is modified to achieve Fmag = -kmx, where km is a constant negative stiffness coefficient, thereby eliminating the non-linear characteristics that cause multi-stable phenomena while maintaining the quasi-zero stiffness vibration isolation performance.
2Force
If the acting force of the negative stiffness actuator is increased to improve vibration attenuation, then the vibration reduction performance is enhanced, but the non-linear characteristics become more significant, resulting in jumping and complex dynamic behaviors
Solution Approach 1:
The patent applies dynamics by making the negative stiffness electromagnetic actuator symmetrical in structure (up-down symmetry) and designing the electromagnetic force to be linearly proportional to displacement. This dynamic design ensures that the electromagnetic force automatically adjusts with displacement in a linear manner, preventing the system from getting trapped in multiple stable states and eliminating jumping phenomena while maintaining enhanced vibration attenuation capability.
3Ease of manufacture
If a mechanical spring type negative stiffness structure is used, then the structure is simple to manufacture, but the control flexibility is limited and cannot achieve optimal vibration isolation performance
Solution Approach 1:
The patent replaces the traditional mechanical spring type negative stiffness structure with an electromagnetic mechanism. This substitution maintains structural simplicity while providing superior control flexibility through the ability to independently adjust electromagnetic parameters (current, coil turns, magnetic circuit design) to optimize vibration isolation performance for different operating conditions.
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 approach linearizes the vibration isolation system, eliminating multi-stable phenomena and complex dynamic behaviors like jumping, while maintaining simplicity and convenience in implementation.
Implementation Method 1
establishing an electromagnetic force expression under magnetic unsaturation, and determining an electromagnetic attraction force of an electromagnet
Data Source
AI summary
The present disclosure is an electromagnetic force control method of a magnetic disk type negative stiffness electromagnetic actuator. The present disclosure relates to the technical field of vibration control. According to the actually required static bearing capacity, the present disclosure determines the positive stiffness k of a mechanical spring required for a magnetic disk type quasi-zero stiffness vibration isolator; and establishes an electromagnetic force mathematical model of a single electromagnet under a condition of magnetic unsaturation. The present disclosure aims at the magnetic disk type quasi-zero stiffness vibration isolator and takes the coil current as an input control variable, so that the electromagnetic force and displacement of the negative stiffness electromagnetic actuator have a linear relationship, thereby changing the non-linear nature of a vibration isolation system, avoiding the multi-stable phenomenon caused by the non-linear electromagnetic force during working, and eliminating complex dynamic behaviors such as jumping when the whole vibration isolator works. Complex sensors and control systems are not needed, and implementation manners are simple and convenient.