Vibration suppression technologies are indispensable to downsizing, weight reduction, and performance improvement of mechanical structures. Active vibration control technique has been employed due to its high damping performance. In general, concrete mathematical models of controlled objects are required to design active vibration control systems, i.e., mathematical modeling&nbsp;of controlled objects is needed. However, such modeling process increases development cost and places heavy burdens on designers. Moreover, modeling errors, which always exist in actual systems, deteriorate their performances, or even destabilize closed-loop systems. Therefore, model-free vibration control, which does not require concrete mathematical models of controlled objects, has been widely studied. Introducing machine learnings or fuzzy control rules is a typical model-free control approach. Many of them have cumbersome and impractical design procedures. In contrast, model-free vibration control approach based on a virtual controlled object has simple design process and is practical and implementable. This approach leads to an active vibration controller based on an actuator model and virtual controlled object. Generally, actuators have parameter uncertainties due to their aging or individual differences. Such uncertainties heavily affect to stability and performance. Therefore, actuator parameter uncertainties should be considered for designing the model-free control system based on the virtual controlled object.This study proposes a novel model-free mixed H2/H∞ vibration controller based on a virtual controlled object considering actuator parameter uncertainty, and its effectiveness is experimentally confirmed. This study employs a proof-mass actuator which is modeled as single-degree-of-freedom (SDOF) system. A virtual controlled object, which is defined as SDOF system, is inserted between the actual controlled object and the actuator model. Considering frequency transfer characteristic from actual controlled object to virtual controlled object, setting appropriate parameters of the virtual controlled object realizes model-free active vibration control. A state equation to design the model-free controller is derived based on the two-degree-of-freedom (2DOF) system composed of the actuator model and the virtual controlled object. The actuator parameter uncertainty is quantitatively modeled in the 2DOF system. Specifically, this study considers uncertainties in the stiffness and damping of the actuator. Then, the 2DOF system composed of the actuator and the virtual controlled object is modelled as a plant with feedback-type fluctuation. Mixed H2/H∞ control theory, a typical linear robust control theory, is applied for the uncertain plant to design a model-free controller with high damping performance and robustness to the actuator uncertainty. An advantage of the proposed method is that traditional matured model-based control theories can be directly applied to design the model-free controller based on the virtual controlled object. Hence, this approach is quite simple and practical and provides good vibration suppression performance. Moreover, the proposed controller has robustness to the actuator parameter uncertainty. The damping performance and robustness to the actuator uncertainty due to the proposed control scheme are verified by experimental studies. Specifically, the proposed model-free mixed H2/H∞ controller is applied to suppress the vibration occurring in a plate structure made of aluminum when the actuator has uncertainty in its stiffness and damping, resulting in effective vibration suppression of the structure.

Experimental Verification of Model-Free Vibration Control Technique Based on a Virtual Controlled Object Considering Actuator Parameter Uncertainty

Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2021/volume/85543

ASME 2021 International Mechanical Engineering Congress and Exposition (IMECE2021)

Supporting the need among researchers worldwide for additional online and multimedia content, ASME now offers the ASME Conference Video Collection. This platform will collect and provide long-term access to conference presentation videos, encompassing all technology areas within ASME's technical conference and events program. About 30,000-40,000 engineers across all mechanical engineering and related disciplines participate in ASME conferences each year. This includes authors of approximately 6,000 to 8,000 technical papers published by ASME, the majority of whom also submit video presentations for our virtual conferences. The video collection will be available as an add-on to existing product packages or as a separate subscription.