Displacement-Optimized Vibration Controller for Shaker Systems
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Solution Overview
Problem
Conventional random vibration test systems face challenges in minimizing displacement at low frequencies, which is crucial for achieving target acceleration profiles without exceeding the physical limitations of shakers, leading to increased costs and complexity in designing systems with larger displacement capabilities.
Innovation Solution
A displacement-optimized vibration controller generates a modified drive signal by using a system inverse Frequency Response Function, separating and optimizing low-frequency components to reduce displacement demand, employing a narrowband signal that varies over time to cover the low-frequency range, and combining it with conventional high-frequency generation methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional random vibration control systems are used, then the target acceleration profile is achieved, but the displacement demand increases significantly at low frequencies
Solution Approach 1:
The patent segments the frequency spectrum into low-frequency and high-frequency components, applying different control strategies to each. The low-frequency portion is processed through a displacement-optimized filter that redistributes spectral content, while high frequencies use conventional random vibration control. This segmentation allows the system to meet acceleration targets while minimizing displacement demand at problematic low frequencies.
Solution Approach 2:
The invention transforms the control signal by modifying its spectral parameters through a displacement-optimized filter. The filter adjusts the power spectral density distribution, reducing energy concentration at low frequencies where displacement demand is highest. This parameter transformation maintains the overall acceleration profile while redistributing spectral content to reduce peak displacement.
2Length of moving object
If a shaker with larger displacement capacity is designed, then the displacement limitation is removed, but the cost and complexity increase significantly
Solution Approach 1:
The patent replaces the mechanical solution (designing a shaker with larger displacement capacity) with a control system solution. Instead of increasing the physical displacement capability of the shaker hardware, the invention uses signal processing and feedback control to manage displacement demand. This substitution avoids the exponential cost and complexity increases associated with building larger-displacement shakers while achieving the same operational goals.
3Length of moving object
If displacement is minimized through optimized control, then the shaker size and cost are reduced, but the control system complexity increases
Solution Approach 1:
The patent implements a feedback control system that continuously monitors the shaker's actual response and adjusts the drive signal accordingly. The feedback loop compares the measured acceleration spectrum against the target profile and modifies the spectral distribution in real-time to minimize displacement demand. This feedback mechanism automates the displacement optimization process, reducing the need for complex manual control system design.
Solution Approach 2:
The invention performs preliminary processing of the random vibration signal through a displacement-optimized filter before the signal reaches the shaker. By pre-shaping the spectral content to minimize low-frequency energy concentration, the system proactively reduces displacement demand rather than reacting to it during operation. This preliminary action simplifies the overall control requirement compared to systems that must react to displacement issues in real-time.
Data Source
AI summary
A control method for a mechanical vibration system independently modifies the higher and lower frequency components of the drive signal satisfying a target profile in a manner that limits displacement in the driven vibration. In particular, phases of the lower frequency components in a preliminary drive spectrum are independently adjusted so that peaks of the respective components are non-simultaneous and distributed in time to avoid contributing constructively. For example, the lower frequency components may be applied as a filter to a narrow-band time waveform, such as one with a swept frequency, to obtain the lower-frequency time waveform. The higher frequency components are randomized in their phase, transformed into the time domain, and recombined with the lower frequency part to obtain the drive signal.