Vibration Isolator with Zero Stiffness and Decoupled Angle DOF
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Solution Overview
Problem
Existing vibration isolators for precision instruments and manufacturing equipment face challenges in achieving low stiffness and high positioning precision, particularly in decoupling the angle degree of freedom between mounting plates, leading to limitations in vibration isolation performance and stability.
Innovation Solution
A vibration isolator with zero stiffness utilizing a spherical air bearing to decouple the angle degree of freedom, combined with a planar and cylindrical air bearing surface, voice coil motors, displacement sensors, and an air pressure close-loop control system, which allows for precise control of the relative position between mounting plates and balanced gravity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If traditional air spring vibration isolator is used, then vertical vibration isolation can be achieved, but horizontal stiffness cannot be sufficiently reduced
Solution Approach 1:
The invention divides the vibration isolation function into separate vertical and horizontal components. The air spring handles vertical vibration isolation, while the air bearing surface handles horizontal vibration isolation and positioning. This segmentation allows each component to be optimized independently, achieving low horizontal stiffness through the air bearing without compromising positioning precision.
Solution Approach 2:
The air bearing surface acts as an intermediary between the upper and lower mounting plates, providing a low-friction interface that enables precise horizontal positioning while maintaining low stiffness. The air film between the air bearing surface and the counter surface mediates the interaction, allowing controlled movement with minimal resistance.
2Force
If pendulum structure is introduced to reduce lateral stiffness, then horizontal stiffness is reduced, but positioning precision deteriorates
Solution Approach 1:
The invention replaces the mechanical pendulum structure with a pneumatic air bearing system. Instead of using a long mechanical pendulum arm that provides low stiffness but poor positioning, the air bearing uses a controlled air film to provide both low friction (enabling low stiffness) and precise positioning through air pressure control and surface geometry.
Solution Approach 2:
The invention uses pneumatic principles to replace mechanical structures. The air bearing surface utilizes compressed air to create a frictionless interface that provides both low lateral stiffness and high positioning precision through controlled air pressure and film thickness, eliminating the need for mechanical pendulum structures.
3Force
If air bearing surface is introduced to decouple vertical and horizontal vibration, then stiffness is reduced, but positioning precision cannot be achieved
Solution Approach 1:
The invention changes the parameters of the air bearing system, specifically the air pressure, film thickness, and surface geometry, to achieve both low stiffness and high positioning precision. By carefully controlling these parameters, the system provides minimal resistance to motion (low stiffness) while maintaining precise positional control through the stiffness of the air film itself.
4Adaptability or versatility
If rubber block is used to provide rotary degrees of freedom, then angle degree of freedom is provided, but decoupling is ineffective due to large angular stiffness
Solution Approach 1:
The invention uses a spherical air bearing instead of a rubber block to provide rotary degrees of freedom. The spherical air bearing uses a film of compressed air between the spherical surface and the mounting plate to provide frictionless rotation with minimal angular stiffness, enabling effective decoupling of rotational movements from translational vibrations.
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 zero additional stiffness, enabling high precision positioning to 10 μm, low frequency vibration isolation, and improved stability by eliminating friction and wear, while maintaining low natural frequencies and high performance.
Implementation Method 1
a spherical air bearing (7) is fitted between the piston cylinder (5) and the upper mounting plate (1)
Implementation Method 2
voice coil motors, displacement sensors
Implementation Method 3
air pressure close-loop control system, which allows for precise control of the relative position between mounting plates and balanced gravity
Data Source
AI summary
A vibration isolator with zero stiffness whose angle degree of freedom is decoupled with a spherical air bearing has a main body, in which a sleeve and a lower mounting plate, a piston cylinder and the sleeve are both lubricated and supported with air bearing surfaces respectively, and the angle degree of freedom between a upper mounting plate and the lower mounting plate is decoupled with a spherical air bearing; a position close-loop control system comprising voice coil motors, displacement sensors, limit switches, a controller and a driver is introduced, and the relative position between the upper mounting plate and the lower mounting plate is precisely controlled.