Dual-Cylinder Servo Actuator for Long-Stroke High-Frequency Loading
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Solution Overview
Problem
Traditional structure test shaking table actuators are unable to generate both large-displacement and high-frequency excitations, which are necessary for simulating the dynamic response of complex structures under earthquakes, due to limitations in power and control accuracy.
Innovation Solution
An electro-hydraulic servo actuator with a combination of a long hydraulic cylinder and a short hydraulic cylinder, along with low and high-frequency electro-hydraulic servo valves, is used to achieve large-displacement and high-frequency loading, employing a control method that separates target acceleration signals into low and high-frequency components for precise control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If traditional short-stroke actuators are used, then high-frequency excitation can be achieved, but large-displacement excitation cannot be achieved
Solution Approach 1:
The actuator is divided into two independent hydraulic cylinders: a long-stroke cylinder for large-displacement low-frequency motion and a short-stroke cylinder for small-displacement high-frequency motion. Each cylinder operates independently with its own servo valve, allowing simultaneous achievement of large stroke and high frequency without the trade-off present in traditional single-cylinder designs.
2Length of moving object
If traditional long-stroke actuators are used, then large-displacement excitation can be achieved, but high-frequency excitation cannot be achieved
Solution Approach 1:
The actuator is divided into two independent hydraulic cylinders: a long-stroke cylinder for large-displacement low-frequency motion and a short-stroke cylinder for small-displacement high-frequency motion. Each cylinder operates independently with its own servo valve, allowing simultaneous achievement of large stroke and high frequency without the trade-off present in traditional single-cylinder designs.
3Device complexity
If a single hydraulic cylinder is used, then structural simplicity is maintained, but the ability to generate both large-displacement and high-frequency excitation is lost
Solution Approach 1:
The actuator is divided into two independent hydraulic cylinders: a long-stroke cylinder for large-displacement low-frequency motion and a short-stroke cylinder for small-displacement high-frequency motion. Each cylinder operates independently with its own servo valve, allowing simultaneous achievement of large stroke and high frequency without the trade-off present in traditional single-cylinder designs.
Solution Approach 2:
The patent merges two specialized actuators (long-stroke and short-stroke) into a single integrated system with a shared piston rod and force applying end head. This combination allows the system to achieve both large-displacement and high-frequency excitation capabilities that neither component could achieve alone, while maintaining a compact structure.
4Use of energy by moving object
If traditional actuators are used, then power consumption is reduced, but control accuracy for large-displacement high-frequency excitation deteriorates
Solution Approach 1:
The actuator is divided into two independent hydraulic cylinders: a long-stroke cylinder for large-displacement low-frequency motion and a short-stroke cylinder for small-displacement high-frequency motion. Each cylinder operates independently with its own servo valve, allowing simultaneous achievement of large stroke and high frequency without the trade-off present in traditional single-cylinder designs.
Solution Approach 2:
The control system uses periodic action by separating the excitation signal into low-frequency and high-frequency components, applying appropriate control strategies to each component through dedicated servo valves. This allows optimal control accuracy for each frequency range while maintaining energy efficiency.
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 actuator effectively generates low-power, high-efficiency, and accurate large-displacement and high-frequency excitations, overcoming the limitations of traditional actuators and enhancing the capability for earthquake simulation tests of large and complex structures.
Implementation Method 1
a low frequency electro-hydraulic servo valve and a high frequency electro-hydraulic servo valve, the low frequency electro-hydraulic servo valve and the high frequency electro-hydraulic servo valve being configured to convert electrical signals into hydraulic pressure flow control signals
Implementation Method 2
control hydraulic pressure changes in left and right chambers of the hydraulic cylinders to implement corresponding piston movements
Data Source
AI summary
The disclosure discloses an electro-hydraulic servo actuator capable of implementing long-stroke and high-frequency loading and a control method. The actuator includes: a long hydraulic cylinder with a piston, a short hydraulic cylinder with a piston, a fixed-end rod, low frequency and high frequency electro-hydraulic servo valves, a left rod chamber, a right rod chamber, a force applying end head, and a force applying end rod. With this structure, the displacement of the piston of the short hydraulic cylinder is a combination of small-displacement and high-frequency movement and large-displacement and low-frequency movement, so as to realize the generation of large-displacement and high-frequency movement. Therefore, a target large-displacement and high-frequency excitation is applied to the specimen under load test. The actuator can output high-frequency and large-displacement target excitation of 0.1 Hz to 200 Hz and 0 mm to 1500 mm, and has a simple mechanical structure, advanced control process, and good practicability.