Vibration Control of Flexible Launch Vehicles Using Fiber Bragg Grating Sensor Arrays

Area of Science:

• Aerospace Engineering
• Control Systems
• Structural Dynamics

Background:

• Mechanical vibrations can compromise control system stability and damage launch vehicles.
• Existing control systems often assume rigid-body dynamics, neglecting crucial vibrational effects.
• Structural resonances and fatigue from vibrational loads pose significant risks.

Purpose of the Study:

• To investigate a real-time method for controlling structural vibrations using fiber Bragg grating (FBG) sensor measurements.
• To develop and validate a model-based robust controller for minimizing vibrations in a launch vehicle test article.
• To assess the controller's performance in reducing peak-peak vibrations in key structural modes.

Main Methods:

• A scaled test article simulating launch vehicle dynamics was designed and constructed.
• Finite element analysis was used to determine modal frequencies.
• A comprehensive model including frequency response, thruster dynamics, and sensor matrices was developed.
• A model-based robust controller utilizing FBG sensor data to command cold gas actuators was designed.

Main Results:

• The controller achieved a 94% reduction in peak-peak vibration for the first mode.
• An 80% reduction in peak-peak vibration was observed for the second mode.
• Controller performance was validated through both simulations and experiments on the test article.

Conclusions:

• The proposed FBG-based control method effectively minimizes structural vibrations in a launch vehicle test article.
• The developed controller demonstrates significant vibration reduction capabilities, enhancing structural integrity and control system stability.
• This approach offers a promising solution for real-time vibration control in aerospace structures.