Yasutaka Tagawa

Controller development for the E-Defense shaking table

Abstract After the 1995 Kobe earthquake in Japan, the National Research Institute for Earth Science and Disaster Prevention (NIED) constructed a new large-scale shaking table as a facility for three-dimensional earthquake damage testing, called E-Defense. The facility was completed in March 2005. E-Defense has the unique capacity to experiment with life-size buildings and infrastructural systems in real earthquake conditions, and is intended to be the ultimate verification tool. The current paper describes the specification of the facility, features of the control system, and some experimental results of the control performance tests. It also describes major ongoing projects at E-Defense.

Characteristic transfer function matrix-based linear feedback control system analysis and synthesis

In this article, the concept of control system synthesis via a method using the characteristic transfer function matrix (CTFM), is explained. Then, the formal definition of CTFM and the associated concept of connectivity are presented. Next, CTFM-based control system analysis and synthesis are discussed, together with the derivation of the necessary and sufficient conditions for the realisation of a proper controller. A summary of the design procedure is presented and three design examples are introduced, in order to illustrate this procedure. Finally, the main conclusions to the work are presented.

Controller Evaluation Technique Using Virtual Test Model in Shaking Table

In control system design for shaking tables, it is well known that many times and kinds of experiments have to be done to find a suitable controller. However, the control experiments with the test model on the shaking table is sometimes very difficult to implement especially for large shaking table such as E-Defense, because it costs very much for constructing and installing the test model on the shaking table. If the test model dynamics can be taken into consideration without using real test model in the experiments, these experiments cost much less than the experiments with real test model. In this study, a controller evaluation technique is proposed using a virtual test model instead of using a real test model. By using the virtual test model, it is possible to evaluate control performance when the test model is equipped on the shaking table, without using the real test model.Copyright

Simulation Based Control and its Application to a Crane System

This paper first describes a basic concept of IDCS (Inverse Dynamics Compensation via ‘Simulation of feedback control’), which is based on feedback simulation. Then, effectiveness of IDCS is demonstrated via inverse dynamics calculation of the non-linear system. In the latter half of the article, IDCS is applied to vibration control problems of a crane system with varying wire length. Several control simulations and experiments are conducted, then the effectiveness of the control system is shown.Copyright

Design Method for Multiinput Multioutput Microvibration Control System.

A design method for a multiinput, multioutput (MIMO) microvibration control method is proposed, based on the model matching method, to provide single-input, single-output systems with almost the same control performance as a sky-hook system by using feedback of absolute acceleration alone. In the method, the system is divided into decoupled modal systems, and the control system for each modal system is designed independently. Simulation studies are carried out for two types of MIMO system with force actuators and displacement actuators, showing the effectiveness of the method and the control systems in isolation performance against micro floor motion, damping performance against direct disturbance, and robustness against parameter variation.

Vibration Control of an Industrial Robot with a Flexible Arm Using IDCS

We propose a fast motion controller for a robot which has a flexible arm using IDCS control scheme. We test IDCS with the controller suitable for vibration suppressing: DMM to the lift table and consider the target tracking of IDCS with suppressing the vibration of the flexible board.

Alternative Control Design Approach to Shaking Facilities for Re-Creating Seismic Motion

The 3-D Full-Scale Earthquake Testing Facility (E-Defense) is now under construction in Miki City near Kobe. When completed, the facility will have a 750-ton shaking table measuring 20m by 15m, with a maximum load mass of 1200 tons. It will be able to create vibration in three dimensions with six degrees of freedom. However, the test model considered for this facility has a mass of 1200 tons compared to the shaking table mass of 750 tons, i.e., 1.6 times as heavy as the shaking table and much larger than ordinary test models. In addition, the vibration characteristics change considerably during the experiment due to the damage done to the test weight. Therefore, a better control design is urgently needed in order to overcome these problems. This research suggests a control method that will reproduce the earthquake wave accurately on the shaking table and will consider the robustness. Moreover, we will verify its efficiency by performing a control experiment using an existing two–dimensional, three-degree-of-freedom small shaking table, to which this control method is applied.Copyright

Control of elevator having parametric vibration using LPV control method: simulation study in the case of constant vertical velocity

A control system for elevator vibration reduction is designed incorporating a new feature, i.e., parameter variation in the elevators dynamics. First, the dynamical model of an elevator is formulated, by assuming that at high speed vertical movement the stiffness of the guide rail varies against the elevator vertical position. Next, a controller is designed with the main objective to reduce vibration caused by any external force. When it is stationary the controller works in reducing vibration due to the shock when a passenger gets in to or get out of the elevator, and when it is moving up and down the controller reduces vibration caused by irregularity or unshape of the guide-rail and by parameter variation. Finally, the performance of the designed controller is evaluated through computer simulation. Simulation results show that the controller designed enhances significantly the performance of the elevator.

Development of sensorless easy-to-use overhead crane system via simulation based control

This paper describes the newly developed overhead crane which has a sensorless vibration control system. Generally, loads which are carried by the overhead cranes are easy to vibrate and only skilled people can operate the cranes. Therefore, a lot of studies have been done to solve this problem by using feedback control with vibration sensors. However vibration sensors often break down in severe industrial environment and more reliable control systems are required. For this reason, we have been developing sensorless control system for overhead cranes. In this paper, we firstly introduce basic idea of simulation based control which is called IDCS, then overview and modeling of the overhead crane is presented. Next, the control system design of the overhead crane is discussed, and experimental results are shown for real overhead crane with 2 axes.

Development of simple operation crane system for the real application

In each industry, the weight of the transportation work and quantity of the load has increased. Thus, now the crane equipment is introduced than ever. For overhead crane used in factories and warehouses, efficient operation which suppresses the swaying of the suspended load during transport is strongly demanded. In particular, it is necessary to suppress the initial shaking or disturbance due to the shift of the center of gravity and the hanging point position at the time of raising the suspended load. Therefore, we need to develop the simple operation crane system that enables the operation of the same level as the person skilled in the crane operation in order to improve the safety and efficiency. The author have investigated the control using Dual Model Matching method based on characteristic transfer function matrix to a configuration of the controller. By implementing feedback control on an actual overhead crane in practical use, the efficacy and operability of the system and the method were discussed. The purpose of this study, by developing the simple operation crane system that allows the same operation as the skilled operator, is to improve the safety and efficiency of the crane operation.