Active Vibration Absorber Feedforward Control for Semiconductor Machines
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Solution Overview
Problem
Conventional vibration absorbers, both passive and active, are ineffective in semiconductor processing machines due to their limited frequency range and slow adjustment time, which makes them impractical for handling varying excitation frequencies, and they often require multiple sensors and complex data processing, increasing costs and reducing performance.
Innovation Solution
An active vibration absorber with a mounting portion, an inertial mass resiliently coupled to it, and a force actuator that moves the mass according to a motion profile derived from the motion command of the positioning system, allowing for real-time tuning and vibration attenuation across multiple frequencies without the need for sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If passive vibration absorbers are used, then the device is simple and effective at a specific frequency, but the effective frequency range is narrow and attenuation decreases rapidly when excitation frequency varies
Solution Approach 1:
The patent transforms the static passive vibration absorber into a dynamic active system by introducing a force actuator that can adjust the absorber's characteristics in real-time. The force actuator applies controlled forces to the absorber mass, enabling the system to adapt its resonance frequency and maintain effectiveness across varying excitation frequencies, thus resolving the contradiction between simplicity and adaptability.
Solution Approach 2:
The patent changes the physical parameters of the vibration absorber dynamically through active control. By using a force actuator to modify the effective stiffness and damping characteristics of the absorber system, the resonance frequency can be adjusted to track varying excitation frequencies, expanding the effective frequency range while maintaining attenuation performance.
2Adaptability or versatility
If adaptive vibration absorbers with motors and feedback control are used, then the resonance frequency can be tuned to match the primary system, but the adjustment time is slow and reliability is poor under extended operations
Solution Approach 1:
The patent replaces the mechanical adjustment mechanism (motors and physical spring stiffness changes) with a non-contact force actuator system. This substitution eliminates mechanical wear and adjustment delays, providing faster and more reliable frequency tuning through direct force application to the absorber mass, thereby improving both response time and operational reliability.
3Measurement precision
If conventional active vibration absorbers with sensors and FFT processing are used, then vibration attenuation can be achieved at monitored frequencies, but the data processing time is long and transient performance is poor for fast varying excitation frequencies
Solution Approach 1:
The patent employs feedforward control by utilizing predetermined motion commands of the positioning system to anticipate vibration excitation before it occurs. By processing the known motion profile in advance and pre-calculating the required counteracting forces, the system eliminates the need for real-time FFT processing and sensor feedback delays, achieving fast transient response and reducing processing time while maintaining frequency accuracy.
4Loss of information
If conventional active vibration absorbers with multiple sensors are used, then vibration signals can be collected for control, but the system cost increases and complexity increases
Solution Approach 1:
The patent extracts and eliminates the sensor subsystem from the conventional active vibration absorber by using feedforward control based on predetermined motion commands. The system obtains vibration information indirectly from the known positioning system commands rather than direct sensor measurement, thereby removing multiple sensors and associated signal processing hardware, reducing both cost and system complexity while maintaining control capability.
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
The solution enables fast and effective vibration attenuation across a wide range of frequencies, reducing the need for sensors and complex data processing, resulting in improved transient performance and lower costs, making it suitable for semiconductor processing machines.
Implementation Method 1
an inertial mass that is resiliently coupled to the mounting portion; and a force actuator which is operative to controllably move the inertial mass relative to the mounting portion
Implementation Method 2
an inertial mass that is resiliently coupled to the mounting portion
Data Source
AI summary
An active vibration absorber is attachable to a structure incorporating a positioning system which serves to vibrate the structure during its operation. The active vibration absorber comprises a mounting portion for attachment to the structure, an inertial mass that is resiliently coupled to the mounting portion and a force actuator which is operative to controllably move the inertial mass relative to the mounting portion. The force actuator is configured to move the inertial mass relative to the mounting body according to a motion profile during a motion cycle of the positioning system in order to attenuate vibrations in the structure. The motion profile is determined from a motion command which is operative to drive the positioning system during the motion cycle.