大槻 真嗣

When a spacecraft lands, the large shock load can lead to undesirable responses, such as rebound and trip. The authors have previously discussed the problem of controlling these shock responses using momentum exchange impact dampers (MEIDs). However, the optimal design parameters of MEIDs for spacecraft landing have not yet been addressed. These parameters are crucial for MEID applications. This paper discusses the parameters of Passive-MEID (PMEID) for a single-axis falling-type problem, which is the most fundamental problem. It is found that the rebound height is proportional to the mechanical energy of the spacecraft. Thus, the optimal design parameters of the PMEID correspond to the parameters that minimize the mechanical energy. A PMEID with the optimal design parameters is called optimal PMEID in this paper. In order to improve the performance of the optimal PMEID, this paper proposes a novel MEID — HMEID (active/passive-hybrid-MEID). The HMEID combines actuators with passive elements such as contact springs. Based on the optimal design results for the MEIDs, this paper applies a stiffness control to the HMEID in order to suppress the mechanical energy further. Simulation studies reveal that the HMEID can effectively reduce the influence of shock responses. The robustness of the HMEID against the landing ground is shown. The feasibility of the HMEID is also discussed. The HMEID is superior to a PMEID, even if the actuator has a dynamics with a large electric time constant.

It is performed to suppress the transverse vibration of the elevator ropes on a high-rise building caused by resonance between building-sway and rope-sway. The elevator rope has the characteristics due to its flexibility and length-varying and some constraints for the active vibration control. Hence, for compensating the influence of the time-varying characteristics and spillover, the nonstationary robust controller which has the robustness against unstructured and structured uncertainties is employed for the active vibration suppression of the rope. The suppression and robust stabilizing performances of the controller are demonstrated through the numerical calculations for the case in which the building is subjected to the ground disturbance like an earthquake and the tension of the rope varies. Thereupon, the control input system actuated by an alternate current motor is located right below the traction sheave and then it moves the rope directly in the presence of gaps between the rope and actuator. Consequently, the nonstationary robust controller shows the advantages in terms of the robustness on the uncertainties and the performance as compared to the optimal controller; and then it can adequately suppress the transverse vibration of the rope.

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.