In this paper, an application of disturbance observers to high speed synchronization of two motion axes is considered. The proposed system consists of two motion axes coupled with a synchronizing controller and two disturbance observers.
First, the effects of disturbance input on the responses of two motion axes coupled with the only synchronizing controller are investigated. Based on the results of investigation, an in-phase disturbance observer and anti-phase disturbance observer are designed and introduced to achieve sufficient robustness and high speed synchronization. Furthermore, a feedforward controller is used to improve the tracking performance. Experimental results demonstrate the effectiveness of the proposed disturbance observers and the feedforward controller for faster removal of the tracking and synchronizing errors.

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This paper presents the optimum control of three dimensional liquid container transfer considering the suppression of sloshing (liquid vibration), and studies on the robustness of sloshing suppression for the change of liquid level, viscosity and so on. Rectangular and cylindrical container are respectively considered, and the straight tranfer path is studied. The pendulum-type sloshing model is used for the present container. Optimum servo control system with Kalman filter is applied, and optimum weighting matrix in LQ problem is determined by using a simplex method. Robustness of the sloshing suppression has been analyzed for the change stated above, and a guid-line of the safety design also given. The usefulness of the present paper has been demonstrated through simulations and laboratory experiments

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This paper gives a controller design method for liquid containers conveyance which achieves multiple control specifications simultaneously. To this end, the two-degree-of-freedom controller structure in terms of stable factorization is employed. The feedforward part is constructed via the convex optimization, where the settling time and the overshoot in containers transfer as well as the liquid sloshing are taken into account simultaneously. The feedback part is designed based on the H^∞ loop shaping method in order to cope with plant model uncertainties. The effectiveness of the proposed control method is evaluated by experiments.

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In this paper, the modeling and optimal control problems are investigated for a class of mechanically flexible cantilevered beams tipped with dynamic actuators on the top. First, considering the mechanism of the tipped dynamic actuator, both dynamics of the beam and the actuator are derived via the Lagrangian formulation. The resultant system is a hybrid system described by an Euler-Bernoulli type partial differential equation and an ordinary differential equation of second-order. Secondly, to suppress the vibration of the beam, based on the derived hybrid system model, we propose the optimal control laws using the dynamic actuators. To obtain the modal expression, a new transformation called the boundary homogenization is introduced. Consequently, the optimal control have a feedback form of the state variables of the beam and the actuator. Finally, several numerical simulation results are presented to demonstrate the good performance of the proposed theory.

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Stabilization of a multi-input multi-output plant with variable operating conditions is discussed. The plant is described as a linear interpolation of proper stable factorizations of nominal transfer matrices representing the behaviors at nominal operating points. In this paper, more than two nominal plant models are considered, in contrast with the case of two nominal models, which has been extensively dealt with so far. To stabilize the closed-loop system, a controller being an interpolation of the stabilizing controllers for the nominal models is employed as well as a fixed controller. The stabilization problems are reduced to certain H^∞ control problems. Sufficient conditions and a design algorithm for the controllers are expressed in the form of LMI (linear matrix inequalities) in the state space.

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