大槻 真嗣

It is well known that the vibration control problem for automobiles and railway vehicles with semi-active suspensions is classified as a control problem in a bilinear system. Bullet trains and railway vehicles have lighter body in order to improve acceleration; these vibrations in the body are easily induced by various disturbances due to rigid and elastic dynamics. Currently, passive dampers such as air suspensions and axle springs are installed on railway vehicle trucks as countermeasures for such vibrations. This study presents an effective controller, based on the H_∞ theory, for vibration suppression in railway vehicles and describes a method of synthesizing this robust controller by considering unstructured and structured uncertainties that are applicable to a bilinear system. The performance of the proposed controller and its robustness toward uncertainties are examined by numerical calculations that simulate a railway vehicle subjected to disturbances due to vertical uneven railway tracks, the variations in its mass due to boarding passengers, and the modeling errors caused by non-controlled modes. This enables a comparison of the proposed control method with the conventional one in terms of the robustness toward parameter variation. Thus, this result shows the high robustness and usefulness of the proposed controller.

Transverse vibrations of ropes spanning a high-speed elevator are induced by resonance when a building sways because of an earthquake or wind force. Hence, an effective solution is demanded. In this study, we undertake to suppress the vibration of an elevator rope by using an input device placed in the vicinity of the upper boundary of the rope. This input device has gaps between an actuator and the rope to prevent the progression of their abrasion. A tionstationary control method is effective for the control of a time-varying system with which an elevator rope and a crane wire are categorized. In addition, a sliding mode controller is robust toward nonlinearity at the position where input is introduced. Thus, in this paper, we present a method of vibration control for the elevator rope, which is based on the nonstationary sliding mode control method using the input device with gaps. The effectiveness and robustness of the proposed controller are examined by numerical calculation that simulates input saturation, stroke limitation, gap-width expansion, and varying parameters, in the presence of model errors of the elevator rope. The results indicate effective vibration suppression and high robustness in the above cases except for the case of varying parameters.

A simultaneous control for vibrations and positions of a controlled object is demanded in the fast-moving machine with a flexible structure such as cranes, transport systems and positioning machines in a plane. Particularly, the positioning machine in a plane has the mass distribution which varies due to a positioning command, thus, it is classified into a time-varying system. This paper presents a synthesis method of the robust input to control simultaneously the position and vibration of the time-varying flexible structures. It is supposed in this paper that the fast positioning machine in plane as the controlled object has the actuator system with a servo mechanism which follows the position or velocity command as a feedfoward control input. And the command is then calculated by the numerical calculation which simulates the feedback control by using the nonstationary robust controller designed by the generalized plant with structured uncertainties. Furthermore, this paper provides a practical methodology so that the command is independent from positioning distance and a schedule and it is also installed into hardware with the reduction of the required memory amount and computing load by the approximation of the command using the Fourier bases. The performance and robustness of the proposed input are examined through the numerical calculation compared with those of a command shaped input. And then the usefulness of the proposed input and the procedure of its installation are obtained.

In this paper, it is performed to suppress the transverse vibrations of elevator-ropes on high-rise building caused by the resonance between building and rope sway. The elevator-rope has the characteristics due to its flexibility and the variation of its length and the constraints for the active vibration control. Hence, for compensating the influence of time-varying characteristics and spill-over, the nonstationary robust controller which has the robustness for the uncertainties categorized by the unstructured and the scaled structured is used for the active vibration reduction of elevator-rope. The suppression and robust performances of the controller are demonstrated through the numerical calculations for the case that a building is subjected to the ground disturbance like an earthquake and the tension of elevator-rope varies. Thereupon, the control input system actuated by ac motor is located below the traction sheave and then it moves the elevator-rope directly with the existence of gap between the rope and the actuator. Consequently, the nonstationary robust controller shows the advantage for the robustness on the uncertainties and the performance in comparison with the optimal one, and it adequately suppresses the transverse vibrations of the elevator-rope.

The transverse vibrations of ropes of a high speed elevator are caused by a resonance with sway of building which is subjected to an earthquake or big wind, hence, an effective solution is demanded. In this research, it is performed to suppress the vibration of elevator rope by using a control device which is located near the upper boundary of rope. The control device has gaps between an actuator and the rope because of preventing abrasions of rope. Furthermore, the nonstationary sliding mode control is effective for the control of a time varying system such as elevator ropes and crane wires and robust for the nonlinearity of a control device. Therefore, this paper presents the vibration control for the elevator rope based on the nonstationary sliding mode control method by using control device with the gaps. The control effectiveness in the case of input saturation, stroke limitation or gap expansion and the robustness of the proposed method in the case of parameter variation and model errors are demonstrated by the numerical calculation. Consequently, the numerical results indicate that the performance of the proposed method is remarkable.

It is well known that a vibration control problem using semi-active suspension for automobiles and railway vehicles is formulated as a control problem of a bilinear system. And the body of a bullet train which is one of railway vehicles is lightened for the speedup, and then its vibrations due to rigid and elastic dynamics are easily caused by various disturbances. Hence, for the present countermeasure, passive dampers such as air suspension and axle spring are located on the truck of railway vehicle. For the practical use and to promote the efficiency of vibration reduction, therefore, this study presents more suppression of vibrations and a synthesis method of robust controller for the bilinear system considering unstructured and scaled structured uncertainties of controlled system. The bilinear robust controller is designed based on H-infinity theory, the scaled structured uncertainty due to parameter variation and error is considered as performance weightings in the time domain, and the unstructured uncertainty due to modeling error is taken into consideration by shaped filters enveloping it in the frequency domain. The vibration reduction performance of semi-active suspension and the robustness for the uncertainties are verified through the numerical calculations for the case that the railway vehicle is subjected to the disturbance due to vertical uneven railway track, the mass variation and the modeling error caused by non-controlled modes. Consequently the effectiveness and robustness of the proposed control method are obtained in comparison with the conventional optimal one.

Sliding mode control realizes desired dynamics of an object system by constraining its states on switching hyperplane designed in phase space. Besides, for control problems of a time-varying system, the controller considering its nonstationary characteristic is effective for its motion and vibration control. Therefore, this paper presents a synshesis method of nonstationary sliding mode control using a time-varying hyperplane. In the proposed method, a time-varying feedback gain derived from the nonstationary control method is adopted as a gradient of time-varying switching hyperplane, and the hyperplane is designed as a continuous function with time. The controller constructed by the time-varying hyperplane and its differential term is suitable for the control of time-varying system, and then the controller shortens the term of reaching mode. Furthermore, this paper gives the proof of stability of closed-loop system including the proposed controller, and examines its performance and the special feature through the numerical calculation for a wire changing its length.

This paper presents a synthesis method of nonstationary robust controller considering uncertainties of time-varying object such as variation of parameter and spillover due to ignored high order modes of object. The variation of parameter is experessed by a scaled structured uncertainty in the time domain. Meanwhile, the influence of spillover is given as a unstructured uncertainty in the frequency domain. In this research, a nonstationary robust vibration controller considering both uncertainties is designed by solving a time-varying Riccati equation derived from a differential game type criterion function. The proposed control method is applied to the transverse vibration control of wire changing its length. Through numerical calculations, the reduction performance of the proposed controller is verified and the advantage with respect to the robustness for the uncertainties is demonstrated.

This study presents a synthesis method of a nonstationary optimal controller for reducing vibration of a time-varying object such as rope of elevator and crane. Moreover, from the viewpoint of wave propagation, we also propose a method of reducing vibration with controller to remove reflected waves. We deal with a rope of elavator of high-rise building as time-varying flexible system and construct the simultaneous model. For this system, controllers to reduce the vibration is designed by using weightings which depend on the velocity and displacement of rope of elevator, in addition, the reflected waves at both ends of its main-rope. The performance of reducing the vibration due to the rope-sway on a high-rise building is examined through numerical calculation. These controllers are compared with the stationary optimal controller for the case that the structure is subjected to artificial wind wave and Chi-Chi earthquake, and their usefulness are shown.