Integrated Active Vibration Control and Structural Health Monitoring of Flexible Spacecraft Panels

Electromechanical Coupling Modeling and LQG Active Vibration Control of CFRP Cantilever Plates Using MFCs

This study addresses the inherently low damping and vibration susceptibility of carbon fiber reinforced polymer (CFRP) laminated cantilever plates by developing a comprehensive dynamic modeling and active vibration control framework. An electromechanical coupling model incorporating macro-fiber composite (MFC) actuators and sensors is established using the first-order shear deformation theory (FSDT) and the assumed mode method, with virtual springs introduced to account for non-ideal clamped boundary conditions. A reduced-order state-space model is then derived through model reduction, and a linear quadratic Gaussian (LQG) controller is designed for optimal state estimation and feedback control. The theoretical model is systematically validated via convergence analysis, ANSYS finite element simulations, and LMS impact hammer testing. The results demonstrate that, with the relative errors of the first four natural frequencies controlled within 2%, the theoretical mode shapes are highly consistent with those obtained from ANSYS simulations. An active vibration control experimental platform is established, and the effectiveness of the control strategy is verified under dual-spectrum harmonic and impact excitations. The results show that the designed LQG controller can effectively suppress multi-modal vibrations, substantially attenuating the response amplitudes of dominant modes and significantly accelerating the transient vibration convergence. This study addresses the challenge of precisely characterizing actual non-ideal clamped boundary conditions. Through model order reduction and closed-loop LQG control experiments, it provides a comprehensive set of theoretical methodologies, numerical solution strategies, and engineering-oriented experimental schemes for the electromechanical coupling dynamic modeling and optimal vibration suppression of CFRP thin-walled composite structures.

Active Vibration Suppression for an Underwater Flexible Structure with Unknown System Dynamics

Vibration Control of a Flexible Space Structure via Reduced Order Finite Element Modeling

This study presents a hybrid modeling and control approach based on the integration of ANSYS and MATLAB for the active vibration control of flexible space structures. The structural dynamics were obtained through high-degree-of-freedom models via ANSYS APDL and transformed into a reduced-order state-space model (ROSSM) representing the rigid-flexible interaction for controller design. Performance analyses of the designed Pole Placement (PP) controller revealed that a damping ratio of 0.70 rapidly stabilizes oscillations under shock inputs; however, it was observed that this high damping performance significantly increases the control force requirements on the actuator. Sensitivity analyses conducted in the final stage of the study confirmed that the controller maintains its stability despite 10% variations in material properties, demonstrating a robust performance against parametric uncertainties.

Theoretical analysis of spacecraft vibration control with a ball-in-track nonlinear energy sink (BIT-NES)

Spacecraft are exposed to severe vibrations during the launching phase. Different vibration absorbers are used to reduce these vibrations, which can lead to failure for the whole mission. Nonlinear energy sinks (NESs) are effective passive devices for mitigating broadband vibration without changing the system characteristics or requiring continuous tuning. This paper proposes a novel application for a ball-in-track nonlinear energy sink (BIT-NES) coupled with a single-degree-of-freedom spacecraft model subjected to lateral harmonic base excitation. A developed two degree of freedom mathematical model simulates the dynamics of a spacecraft coupled with a BIT-NES, demonstrating its effect on the vibration suppression for spacecraft during launching phase. The steady-state response is obtained analytically using the Harmonic Balance Method (HBM) up to the third harmonic for nonlinear terms which are main terms in the model and is verified against numerical time-domain integration using the ODE45 solver. The agreement between the analytical and numerical results verifies the proposed mathematical model. This model is used in parametric studies to show the effect of varying BIT-NES main parameters on vibration mitigation for aerospace applications. Changing the mean track radius reduces spacecraft vibration amplitudes by 45%, while NES mass variation results in a 41% reduction in vibration amplitude, indicating the robustness of this passive vibration absorber in aerospace applications.

Accelerometer-in-the-loop safe learning control of mesh-order vibrations in cycloidal drives.

Cycloidal (RV-type) reducers are widely used in industrial robot joints due to their high torque density and low backlash, yet their multi-mesh transmission path produces structured, operating-point-dependent vibration components at the disc-mesh order and associated harmonics and sidebands. This paper presents a real-time, accelerometer-in-the-loop vibration suppression framework that reduces these components online while maintaining tracking performance within the bounds observed in our experiments and operating within predefined safety limits. A tri-axial accelerometer mounted on the reducer housing provides high-bandwidth vibration measurements from which order-synchronous, band-limited metrics are computed in streaming form. These metrics define both the optimization objective and vibration exposure constraints. The control architecture retains the vendor servo loops and adds a vibration-targeted layer combining a low-dimensional anti-resonance parameterization (adaptive notch shaping and narrowband feedforward cancellation aligned with the estimated mesh-order family) with a safety-certified contextual Bayesian optimization module that adapts the parameters as a function of operating context (speed, load proxy, and temperature proxy). A barrier-function-based safety filter runs at the servo rate to enforce constraint handling during operation; its effect is evaluated empirically through logged interventions and constraint statistics. Experimental evaluation on a cycloidal joint testbed across multiple speeds and load levels shows attenuation of the dominant mesh-order vibration component and its harmonics. Tracking accuracy and safety-related signals remained within preset limits during the tested operating conditions. The proposed approach provides a deployable pathway for online vibration minimization in cycloidal robot joints without requiring high-fidelity internal contact models, and its logged parameter trajectories and order-tracked metrics also offer a foundation for condition-aware adaptation over long-term operation.

An Improved Model Reference Predictive Control Method for Building Mass Dampers