The Proportional-Integral-Derivative (PID) controller structure is very widely used in industrial applications. Its structural simplicity and ability to solve many practical control problems have contributed to this wide acceptance. Recently, the parameterization of all stabilizing PID controllers has been considered. This method obtains admissible sets of PID parameters to guarantee the stability of a closed-loop system. However, several difficulties remain with this method. One is that admissible sets of P-parameters, I-parameters and D-parameters are related to each other. Another is that there are plants that cannot be stabilized by a PID controller. To overcome these problems, Yamada and Hagiwara proposed a design method for modified PID controllers that stabilize the closed-loop system for unstable plants, while allowing admissible sets of P-parameters, I-parameters and D-parameters to be independent of each other. However, no method has been published that can guarantee the stability of PID control systems for multiple-input/multiple-output plants, or find admissible sets of P-parameters, I-parameters and D-parameters that both are independent of each other and guarantee the stability of a PID control system. We propose a design method for modified PID controllers that achieves these goals.

抄録全体を表示

In this paper, we discuss integrated vehicle slip ratio control under both deceleration and acceleration without the need for controller switching, and also propose a design method for such an integrated slip ratio controller based on the slip ratio dynamics. When a vehicle switches from acceleration to deceleration and vice versa, the slip ratio varies discontinuously. Here, the slip ratio is approximated to a continuous function by using a sigmoid function. And a controller is then designed by using feedback linearization based on the approximated slip ratio. The stability of the designed control system is proven by Lyapunov stability theorem. Furthermore, we propose a robust control method based on a disturbance observer and sliding mode control theory. Finally, the effectiveness of the proposed control method is verified through numerical simulation.

抄録全体を表示

Recent years, the number of nuclear families is rapidly growing. So the development of a human-friendly-robot which can take care of human daily life is strongly desired. This robot has to work just like a human, so, it is needed to have a dexterous soft hand in the robot. Therefore, we have developed an artificial soft gripper. This robot hand which has five fingers is made of silicone rubber. We also developed the hand which could be used to achieve several works just like a human hand. For example, it can grasp some objects that have the different shape and stiffness. Since it is made of silicone rubber, there is little damage to the object. However, the finger could not generate a larger force, less than 3N. In addition, it needs a skill and time to make the finger. In this study, we proposed and tested a bending actuator that could be easily constructed by putting the McKibben artificial muscle into the flexible tube. We also investigated the generated force and bending angle of the actuator. As a result, the generated force of the actuator was improved about 8.5 times as large as previous one. We also improved the bending actuator by changing the tube and the slit of the flexible tube. And the analytical model for the bending actuator was proposed and the calculated results were compared with the experimental ones.

抄録全体を表示

In this paper, a human arm-like robot control scheme is proposed based on time-varying viscoelastic properties which consist of multi-joint stiffness and multi-joint viscosity during human arm movements and a modified forward gaze model. In general, in human multi-joint arm movements, the multi-joint torque is assumed to be a function of multi-joint stiffness matrix, multi-joint viscosity matrix, and motor command descending from central nervous system (CNS). In order to make the present human arm-like robot move like a human multi-joint arm, a feedback controller and a modified forward gaze model are presented in the human arm-like robot control system. That is, the feedback controller is designed to obtain desired motion mechanism based on real measured data from viscoelastic properties of human multi-joint arm, and the forward gaze model in which steering gains are modified using a cost function is used to compensate the term related to the effect of CNS. The effectiveness of the proposed method is confirmed by the simulation results based on experimental data.

抄録全体を表示

In this paper, a new perturbation method is proposed, and is shown that the correction vector can be calculated shorter than ever. And, the computing efficiency of the response surface optimization method could improve greatly by applying perturbation method with complementary term to example analysis in the optimization of vibration characteristics by the response surface methodology and by finishing eigenvalue analysis which takes most computing time just once. Moreover, the validity and effectiveness is examined by examples by inducing approximately estimated formula of the vibration response value based on orthogonal polynomial. Lastly, it is shown that the computing time is shorten greatly compared with former method by applying this method to analysis of optimization problem of vibration characteristics.

抄録全体を表示

Players often say that some strings provide a better grip and more spin than others, but ball spin did not depend on string type, gauge, or tension in pervious laboratory experiments. There was no research work on spin to uncover what is really happening during an actual tennis impact because of the difficulty of performing the appropriate experiments. The present paper clarified the mechanism of top spin and its improvement by lubrication of strings through the use of high-speed video analysis. It also provided a more detailed explanation of spin behavior by comparing a racket with lubricated strings with the famous “spaghetti” strung racket, which was banned in 1978 by the International Tennis Federation because it used plastic spaghetti tubing over the strings to reduce friction, resulting in excessive ball spin. As the main strings stretch and slide sideways more, the ball is given additional spin due to the restoring force parallel to the string face when the main strings spring back and the ball is released from the strings. Herein, we also showed that the additional spin results in a reduction of shock vibrations of the wrist joint during impact.

抄録全体を表示

While some tennis racket strings have more grip than others do, this does not guarantee that they will impart more spin to a tennis ball. Experiments with hand-held rackets are required to determine the longstanding question of how players can discern that different strings behave differently when laboratory tests indicate that they should play the same. In a previous study, we clarified the top-spin mechanism of a tennis racket by using high-speed video analysis on a tennis court for the first time. Furthermore, we improved it by using lubricated notched nylon strings. These experiments revealed that the more the main strings stretch and bend laterally, the more spin is imparted to the ball. This is due to the restoring force being parallel to the string face when the main strings spring back and the ball is released from the strings. Notched strings reduce the spin rate, but this can be effectively counteracted by employing lubricants. Furthermore, we found that imparting more spin reduces shock vibrations on the wrist during impact. The present study revealed that a ball has a 40% lower spin rate when hit with a racket with notched strings than with one with unnotched strings in the case of nylon (it had to be determined whether new strings or lubricated used strings give more spin). The experiments also showed that 30% more spin is imparted to a ball when the string intersections are lubricated by oil than when notched used nylon strings are used. Furthermore, we found that used natural gut notched strings reduced the spin rate by 70% compared to when new natural gut unnotched strings are used. We also investigated different top-spin behaviors obtained when professional and amateur tennis players hit a ball.

抄録全体を表示

This study investigates the influence of in-plane vibration on the construction of statistical energy analysis (SEA) models of flexural vibration in plate structures. A simple system is used that consists of two flat plates connected in an L-shaped configuration. For two SEA models, the loss factors related to flexural vibration are calculated by the finite element method, both with and without the in-plane vibration being taken into consideration. Differences occur in the flexural vibration loss factors in the frequency bands corresponding to the natural frequencies of the in-plane vibration in the unconnected plates. The subsystem energy, averaged over frequency and space, also shows the influence of in-plane vibration. As a result, a new method is developed to evaluate the effects of in-plane vibration on constructed SEA models of flexural vibrations. It is demonstrated that the method is useful in identifying the frequency bands affected by in-plane vibration and in determining under- or over-estimation of the loss factors.

抄録全体を表示