Active Vibration Isolation Sensor Stiffness Segmentation
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Solution Overview
Problem
Existing active vibration isolation systems face challenges in accurately isolating payloads from environmental vibrations due to the 'horizontal tilting problem', where gravitational forces cause false vibration signals, degrading performance, especially when measuring horizontal vibrations.
Innovation Solution
The system employs a vibration sensor with a low stiffness connection to the payload for rotation perpendicular to the gravitational force and a high stiffness connection for measuring vibrations, decoupling the sensor from tilting vibrations, thereby preventing erroneous displacement signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a vibration sensor is rigidly connected to the payload for measuring horizontal vibrations, then the measurement precision is improved, but the sensor becomes sensitive to gravitational forces during tilting, causing false vibration signals
Solution Approach 1:
The connection between the vibration sensor and payload is segmented into different stiffness characteristics: high stiffness for the measurement direction (horizontal vibrations) and low stiffness for the tilting direction. This allows the sensor to accurately measure horizontal vibrations while being decoupled from gravitational effects during payload tilting.
Solution Approach 2:
The connection structure is designed with non-uniform stiffness properties: high stiffness in the horizontal measurement direction to ensure accurate vibration detection, and low stiffness in the tilting direction to prevent gravitational forces from causing false signals. This local differentiation of mechanical properties resolves the contradiction.
2Device complexity
If passive isolation methods using mechanical springs or elastomers are used, then the system complexity is reduced, but the isolation performance is insufficient for current demanding applications
Solution Approach 1:
The system transitions from static passive isolation (springs and elastomers) to dynamic active isolation. The connection allows dynamic adjustment of stiffness characteristics through active control, enabling the system to adapt to varying vibration conditions and achieve superior isolation performance while maintaining manageable complexity.
Solution Approach 2:
The isolation system employs variable stiffness characteristics rather than fixed passive elements. By changing the effective stiffness parameters dynamically based on operating conditions, the system achieves high isolation performance across different frequency ranges and vibration amplitudes without requiring overly complex mechanical structures.
3Measurement precision
If the sensor stiffness coupling to the payload is increased for better vibration detection, then the measurement precision is improved, but the compliance increases, degrading isolation performance
Solution Approach 1:
The stiffness coupling is segmented into direction-specific properties: high stiffness in the horizontal measurement direction for accurate vibration detection, and low stiffness in the tilting direction to maintain isolation compliance. This directional segmentation allows simultaneous achievement of both measurement precision and isolation stability.
Solution Approach 2:
The sensor-payload connection exhibits locally differentiated stiffness: high stiffness where vibration measurement is needed (horizontal axis) and low stiffness where compliance is needed for isolation (tilting axes). This local quality differentiation resolves the contradiction between measurement precision and isolation stability.
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 configuration significantly improves vibration isolation by accurately distinguishing between tilting and horizontal vibrations, enhancing the system's ability to isolate and dampen vibrations without increasing compliance, leading to improved performance even at low frequencies.
Implementation Method 1
the gravitational force (or gravitation vector) is perpendicular to the direction of measurement
Implementation Method 2
Due to the high stiffness coupling in all degrees of freedom between the sensor frame and the payload, the sensor however, translates and rotates in the same way as the payload
Implementation Method 3
The electronic output of the sensor is (filtered and) fed back to the actuator that compensates for the undesired vibration
Data Source
AI summary
An active vibration isolation and damping system (11) comprising a payload (12) that has to be isolated or damped, a vibration sensor (14) for detecting a vibration of the payload, an actuator (15) for moving the payload relative to a bearing body (13) supporting the payload, and a controller (16) for providing the actuator with a signal that is representative for the vibration. The system provides a solution for the tilting problem by applying a vibration sensor that has a low stiffness connection to the payload (12) for rotation along an axis (17) perpendicular to the gravitational force (18), and a high stiffness connection to the payload (12) for the vibration detectable with the vibration sensor.