Takayoshi Kamada

Active vibration control of frame structures with smart structures using piezoelectric actuators (Vibration control by control of bending moments of columns)

A smart structure was tested for active vibration control of frame structures in which the bending moment of the columns was controlled by stack-type piezoelectric actuators integrated into the columns. Excitation tests were carried out for a model of a four-storey building 3.7 m in height and 2000 kg in total weight in which thirty-two piezoelectric actuators were used for bending moment control. The actuators were installed in two ways: in one case eight actuators were attached to each column of the first storey, and in the other case four actuators were attached to each column of the first and second storeys. Two control strategies, a model-matching method and the control theory, were examined for the smart structure. The tests showed that the smart structure could effectively reduce the responses of the building model, and all combinations of actuator installation method and the control strategy yielded almost the same performance.

Target Following Brake Control for Collision Avoidance Assist of Active Interface Vehicle

In this study, target following brake control for collision avoidance assist by proposing active interface vehicle is developed. In this paper, the collision avoidance assist method for stopped vehicle in front, for recovering the recognition delay by inattentive driving is proposed. The system sets deceleration motion with the desired deceleration for the purpose of collision avoidance, etc. after the discovery in the driver in respect of the obstruction in front. In comparison with brake action of actual driver, the investigation which supplemented the shortage deceleration was carried out, to confirm the collision avoidance performance

Effect of wheel-slip prevention based on sliding mode control theory for railway vehicles

It is important to consider the robustness when designing brake control systems, because of the models uncertainties that result from the nonlinear characteristics of wheel-to-rail adhesion forces and brake material friction coefficients. This paper presents the experimental results from the new wheel-slip prevention control using nonlinear robust control theory. The authors performed experiments for the proposed wheel-slip prevention control to compare it with the conventional control laws. The experimental results proved the comparative effectiveness of the proposed control and showed high brake performance under nonlinear characteristics of brake dynamics.

Study on automatic path tracking using virtual point regulator

This study discusses a vehicle path tracking strategy using a virtual point ahead of the vehicle to trace the desired path. Although the vehicle center of gravity can also be employed for the tracking, it is impossible to design the yaw control independently from the controlled lateral motion. By contrast, the yaw motion, as well as the lateral motion, can be controlled to obtain its own desired performance when the virtual point is used for the tracking, although this applies with certain reservations. Additionally, employing the virtual point also secures good robust stability and disturbance suppression performance of the control system.

Active vibration control of flexural-shear type frame structures with smart structures using piezoelectric actuators

To apply smart structures to buildings, a new vibration control strategy is proposed for flexural-shear type frame structures with smart structures using piezoelectric actuators. Actuators are incorporated in columns, and the response of the entire structure is reduced by control of the bending moment and axial force of the columns. Combined application of these two controls is performed by arrangement of actuators. Two control strategies were tested: one involves the use of a model matching method and the other is based on control theory. Excitation tests were conducted with a four-storey frame structure with a total weight of 2000 kg and a height of 3.7 m, having H-section steel beams incorporating actuators as columns. The effectiveness of combined use of bending moment control and axial force control of columns with smart structures was confirmed.

Active Vibration Suppression of Lightweight Railway Vehicle Body by Combined Use of Piezoelectric Actuators and Linear Actuators

In recent years, railway vehicle are becoming lighter because this corresponds not only to the improvement of the running speed but also to the reduction of running cost and environmental noise, especially for ultra-high-speed vehicle such as new Shinkansen and MAGLEV vehicle. However, this causes the deterioration of riding comfort. Bending vibration control method using piezoelectric actuators were proposed and good control performances were obtained through simulations and experiments. In this paper, active vibration control by combined use of piezoelectric actuators and linear actuators is investigated. Elastic vibrations are suppressed by piezoelectric actuators and rigid-body vibrations are reduced by linear actuators. Simulation studies and experiments using scale model were conducted and the effectiveness of the proposed control was confirmed.

Development and application of induced-strain actuators for building structures

Induced strain actuator (ISA) can change their own shapes according to external electric/magnetic fields, and vice versa. Recently these materials have been widely used for the small/precision. The objectives in this study are to develop smart members for building and to realize the smart, comfortable and safe structures. The research items are 1) Semi-active isolation of structures using piezoelectric actuator, 2) Using ISA as sensor materials and 3) Improvement of Acoustic Environment. Semi-active base isolation system with controllable friction damper using piezoelectric actuators is proposed. Simulation study was carried out, and by semi-active isolation, it could be realized to reduce response displacement of the structure to 50% of values of the passive isolation. ISA materials can act as sensors because they cause change of electric or magnetic fields under deformation. PVDF sensors are suitable for membrane structures. We evaluate performance of PVDF sensors for membrane structures by experiment. Polymer based ISA films or distributed ISA devices can control vibration mode of plane members. Applications to music halls or dwelling partition walls are expected. Results of experimental studies of noise control are discussed.

Suppression of railway vehicle vibration by shunt damping using stack type piezoelectric transducers

In recent years, railway vehicles have become lighter, corresponding to improvement in the running speed. However, this causes the deterioration of the body rigidity, and leads to the increase in a vertical bending vibration of the body, because the natural frequency of the first bending vibration overlaps with a humans uncomfortable and sensitive frequency band. Many vibration suppression strategies have been proposed, i.e. a method to conduct active control for the secondary suspension system between the body and bogie, and a method to attach visco-elastic layers and constraint layers on the outside sheeting of the car body. In this paper, new control methods by shunt damping using stack type piezoelectric devices are proposed and the effectiveness and the robustness of designed circuits were confirmed through 1/6 scale model experiments.

Active vibration control of frame structures of shear and bending type with smart structure using piezoelectric actuator

To apply smart structures to buildings, a new vibration control strategy is proposed for flexural-shear type frame structures with smart structures using piezoelectric actuators. Actuators are incorporated in columns, and the response of the entire structure is reduced by controlling the bending moment and axial force of columns. Combined application of these two control is performed by arrangement of actuators. Two control strategies were tested. One is model matching method and author is H(infinity) control theory. Excitation tests were conducted with a 4-story fame structure of total weight 2,000 kg and height 3.7 m having H-steels incorporating actuators as columns. Effectiveness of combined use of bending moment control and axial force control of columns with smart structures was confirmed.

Parallel Factor Analysis of Driver's EEG in Lane Change Maneuver for Cooperative Driver Assistance Systems

Abstract Vehicle technology of the better interaction between human and machine has been called human-electronics in Japan. It is necessary to obtain better relationship between human and vehicle. A drivers information, which can be obtained from steering operation, pedal operation, camera images and physiological information, particularly is important to find a method to determine a drivers operational intention. In terms of using this physiological information, an area of focus is using brain activity. Recently, some former researches haves been reported about the investigation of the brain activity of the driver. The traditional decomposition of the electroencephalograph (EEG) has been based on the two-dimension components. In the multiple electrode analysis of EEG, the frequency-spatial domain and the time-spatial domain have been used. However, these conventional methods can only use two-dimensional data. As a multi-channel EEG analysis using multi dimensional data, parallel factor analysis (PARAFAC) method is based on the report. In this paper, we described that the drivers EEG during lane change was decomposed by PARAFAC and we investigated the factor of recognize and judgment from that decomposition result. Consequently, Common to the all subjects has 2 factors which were in the 5-8 Hz and 8-13 Hz. Those factors considered that they were changed by the drivers mental state, during recognition for alpha wave and during judgment for theta wave.