Satoshi Nakano

Bio: Satoshi Nakano is an academic researcher. The author has contributed to research in topics: Computer science & Convex optimization. The author has an hindex of 1, co-authored 3 publications receiving 2 citations.

Design method of tuned mass damper by LMI based robust control theory for seismic excitation

Abstract: This paper presents a new design method based on a robust-control strategy in the form of a linear matrix inequality (LMI) approach for a passive tuned mass damper (TMD), which is one of the common passive-control devices for structural vibration control. To apply the robust control theory, we first present an equivalent expression that describes a passive TMD as an active TMD. Then, some LMI-based condition is derived that not only guarantees robust stability but also allows us to adjust the robust H¥ performance. In particular, this paper considers the transfer function from a seismic-wave input to structural responses. Unlike other methods, this method formulates the problem to be a convex optimization problem that ensures a global optimal solution and considers uncertainties of mass, damping, and stiffness of a structure for designing a TMD. Numerical example uses both a single-degree-of-freedom (SDOF) and 10DOF models, and seismic waves. The simulation results demonstrated that the TMD that is designed by the presented method has good control performance even if the structural model includes uncertainties, which are the modeling errors.

Improving habitability for wind-induced structural vibration by equivalent-input-disturbance approach

Abstract: This paper improves the habitability of a building for wind load using an equivalent-input-disturbance (EID) approach. In these few decades, many high-rise buildings are constructed around the world. The influence of wind load is large for high-rise buildings, and it causes a decrease in habitability. Habitability relates to the acceleration of a structural response. To improve the habitability of a building for a wind load, we use a lagged-derivative function and EID approach. An EID approach estimates the effect of a disturbance on an output signal. Thus, an acceleration has to be output to estimate an EID. This paper uses a lagged derivative to output the acceleration. The numerical verification uses a building model of 240m and demonstrates that the presented method suppressed the absolute acceleration and improves the habitability of a building to a wind load.

Wind-load estimation with equivalent-input-disturbance approach

Abstract: This paper presents a new method to estimate an along-wind load that contains a mean component using an equivalent-input-disturbance approach. An along-wind force contains both mean and fluctuating components. However, most studies estimate only fluctuating components. Moreover, these studies assume that the damping matrix is a Rayleigh one. In contrast, this paper presents a method that estimates both the mean and fluctuating components using velocity response. Furthermore, this method does not require that the damping coefficient is Rayleigh damping. The numerical verification verifies using an 11 degree-of-freedom(DOF) model of a seismic-isolated building. The results presented that the presented method accurately estimates an along-wind load.

Active Structural Control of Base-Isolated Building Using Equivalent-Input-Disturbance Approach with Reduced-Order State Observer

Abstract: Active base isolation has been studied in the last few decades to improve the control performance of base isolation. As a two-degree-of-freedom active disturbance-rejection method, the equivalent-input-disturbance (EID) approach shows its validity for structural control. It uses a state observer to estimate the effect of disturbances on a control input channel. However, since the model of a base-isolated building has high degrees-of-freedom, a resulting control system has a high order. Thus, the use of a full-order state observer results in the complexity of a control-system implementation. To solve this problem, this paper presents an EID control system that uses a reduced-order state observer (ROSO) to reduce the expense of control-system implementation and ensure system reliability. First, the condition of using an ROSO in an EID control system is derived, and the configuration of an ROSO-based EID control system is presented. Next, the concept of perfect regulation is used to design the gain of the state observer. A stability condition of the system with prescribed control performance is derived in the form of a linear matrix inequality (LMI) that is used to design the gain of the state feedback. Finally, the seismic control of a base-isolated building demonstrates the validity of the method.

Finite-Horizon ${l}_{2}-{l}_{\infty}$ State Estimation for Networked Systems Under Mixed Protocols

Abstract: Dear Editor, This letter is concerned with the finite-horizon $l_{2}-l_{\infty}$ state estimation (SE) problem for a class of networked time-delay systems where the measurements are transmitted through two individual communication channels. With the aim of preventing the transmitted data from conflicts, the signal transmissions over such the communication channels are scheduled by different communication protocols, namely the stochastic communication protocol (SCP) and Round-Robin protocol (RRP). A mixed scheduling model is proposed to describe the transmission behaviors subject to such two protocols. The objective of this letter is to design an estimator such that the estimation error achieves the desired finite-horizon $l_{2}-l_{\infty}$ performance in the mean square. By using the Lyapunov stability theory, a sufficient condition is proposed to guarantee the existence of the desired estimator. An illustrative simulation example is given to verify the effectiveness and correctness of the proposed design scheme.