In order to improve control performance given by stable controller for disturbance suppression problem of two-inertia system with low stiffness and high inertia ratio, this paper proposes a simple structure of controller which has a similar characteristic of unstable controller given by H_∞ control design. The proposed controller has two tunable parameters, and a tuning procedure to minimize the closed-loop gain with desired stable margins is given, by which the proposed controller can be easily adjusted when physical parameters are changed. The optimal closed-loop gain by conventional control method (proportional control) and an rate of improvement by proposed method are theoretically given in terms of physical parameters of plant. The validity of the proposed method is shown by experimental results.

The periodic behavior of macroeconomic indicators or business cycles is a common observation in the economic system. In the past, business cycle modeling often involved the use of non-linear economic dynamic theory, general equilibrium theory, and methods to analyze complex systems, such as agent-based modeling and complex network theory. Several studies have shown that crisis and synchronization in business cycles can be modeled using threshold characteristics in the economic systems. In a non-linear system, it is well known that additive noise leads to qualitative transformations in system behavior, such as coherence resonance, stochastic resonance, and noise-induced transitions (referred to as noise-induced phenomena in this study). Recent studies have shown that noise-induced transitions arise in the non-linear economic business cycle model with multiple attractors around the sub-critical Hopf bifurcation. However, the relationship between the threshold characteristics in the economic dynamics and noise-induced phenomena has not been studied. In this study, we focus on the threshold characteristic of the Kaldor business cycle model under the bias of income, and show that coherence resonance and stochastic resonance can be produced as an effect of this threshold characteristic.

This paper presents a novel simulation system to analyze adaptive behaviors of agents in a deregulated electricity retail market. We develop a learning framework which enables the agents to autonomously acquire the action rules. In this paper, the XCS (extended classifier system) is employed as a learning algorithm of the agents. XCS can efficiently generate action rules in the dynamic environment such as the deregulated retail market affected by the interaction among many agents. The artificial retail market shows complicated behavior by the interaction among the agents, and therefore the agent-based simulation can provide some technical findings due to the interactions among autonomous agents which are not always rational in a sense of optimal behaviors. We provide new insights based on the behavior analysis of the agents in the artificial retail market simulation.

The bilateral control system of the nonlinear flexible master-slave arms with the time-varying delay is investigated in this research. Moreover, it is considered that the nonlinear flexible slave arm contacts with the obstacle during the motion. The master arm is considered as the rigid arm and a high-geared servomotor is introduced to drive the flexible slave arm. The network between the master arm and the slave arm causes the time-varying delay. The PD- and PDS-controllers are designed for controlling the master and slave arms. By means of the Lyapunov theorem, the stability and the passivity included the contact force are proved. Finally, the performance of the proposed system is investigated by using numerical simulations.

This paper deals with formation control of quadrotors based on interconnected positive linear systems. One of the applications of interconnected positive linear systems is formation control including switching of SISO positive and stable linear subsystems. However, mechanical systems such as quadrotors are neither linear nor positive. This paper proposes an extended feedback linearization technique that is able to convert the dynamics of the reference point of a quadrotor, a virtual rigid body dynamics, into four double integrators with respect to the reference point in the space and yaw angle. In contrast to traditional exact feedback linearization techniques, the extended feedback linearization technique of the quadrotor does not require the jerk to be estimated. The extended feedback linearization and a local linear feedback law are employed to transform each coordinate of the reference point into a SISO positive and stable subsystem. As a result, the reference points as well as the mass centers of the quadrotors achieve formation in the framework of interconnected positive linear systems. The results are illustrated by numerical examples.