Kazuhiko Terashima

Robust liquid container transfer control for complete sloshing suppression

The paper is concerned with the advanced control of liquid container transfer, with special consideration given to the suppression of sloshing (liquid vibration) while maintaining a high speed of transfer for the container. In order to construct a high speed transfer system for a liquid container that satisfies the reduction of endpoint residual vibration and has a robustness to change in the static liquid level, a suitable nominal model was adopted and an appropriate reference trajectory was determined by the optimization method of Fletcher and Reeves (1964). Based on the above command inputs and using a suitable nominal model, an H/sup /spl infin// feedback control system was applied to this process, and its effectiveness is shown through simulations and experiments. Furthermore, an active control method that takes into account the rotational motion of the container in addition to the linear transfer motion is presented, which can achieve complete suppression of sloshing during the whole transfer process.

Sloshing analysis and suppression control of tilting-type automatic pouring machine

Abstract This paper presents a two degree-of-freedom control that allows the molten-metal of tilting-type pouring machine to attain the requested angle during the backward-tilting portion of its cycle and to reduce the sloshing (liquid vibration) caused by this motion. To this end, the feedforward part is constructed using the input shaping method and a feedback compensation is performed based on the H ∞ loop shaping method. Furthermore, two kinds of model are used and useful ways of applying two different models to the same problem is presented with the aim of integrating fluid analysis and control design.

Semi-autonomous obstacle avoidance of omnidirectional wheelchair by joystick impedance control

An omnidirectional wheelchair is highly maneuverable in narrow or crowded areas such as residences, offices and hospitals. A semi-autonomous control method for omnidirectional wheelchairs is proposed. In addition to allowing the normal joystick commands of the wheelchair operator, this method provides a collision avoidance function using external sensors. The proposed method does not employ unexpected autonomous movements conflicting with the operators joystick commands, because this tends to create discomfort for users and can be dangerous for infirm patients. Instead, the proposed method merely alerts the operator to the presence of an obstacle; this is accomplished by changing the impedance of the joystick essentially creating resistance against moving the joystick in the dangerous. direction. The wheelchairs motion remains controlled only by the operators joystick commands, while a collision is avoided successfully. The effectiveness of the proposed method is shown by experiments with an onmidirectional wheelchair.

Sloshing suppression control of automatic pouring robot by hybrid shape approach

This paper presents the advanced control of an automatic pouring process, with special attention being paid to the suppression of sloshing (liquid vibration) as well as to high-speed transfer in a 3D space. In order to realize these objectives, a novel automatic pouring robot (APR) is developed. The controllers are designed by a hybrid shape approach, considering both time and frequency characteristics, in order to construct an APR which satisfies various control specifications such as the sloshing suppression, overshooting, the settling time and restriction of the control inputs magnitude. The effectiveness of the proposed system is shown through some experiments.

Evaluation of effectiveness of a power-assisted wire suspension system compared to conventional machine

Our proposed power-assisted wire suspension system has three advantages. First, the structure is simple, and the cost is lower than that of other rigid systems, because the mechanism is based on an overhead crane. Second, it is easy to effect sequence control using this system because the sequence control is based on the velocity control. Finally, this system is expected to supply efficient conveyance by any operator, because operators can move heavy objects directly with two hands. In this study, we compared the effectiveness of the proposed power-assisted system that has sequence control with the conventional operation using buttons through experiments involving the measurement of the precision of the positioning and the work time needed to assemble objects.

Motion control of liquid container considering an inclined transfer path

Abstract The present paper is concerned with advanced control of liquid container transfer along an inclined transfer path, paying special attention to the suppression of sloshing (liquid vibration). To suppress sloshing in the container during acceleration and deceleration along the inclined transfer path, we present a method to actively control the containers rotational motion. This system is useful for saving space in factories and optimizing foundry processes. The effectiveness of the proposed system is demonstrated through simulations and experiments.

Identification and hybrid impedance control of human skin muscle by multi-fingered robot hand

This paper proposes an intelligent massage control system by using multi-fingered robot hand with hybrid impedance control, which is able to create the movement and the force of robot such as the humans massage. Therefore, the various massage points, such as the change of the stiffness of human skin muscle, can be controlled by using impedance control method. The hybrid impedance control is comprised of the two methods of the position-based and the force-based impedance control were applied. The position-based impedance control is used to control the lateral position of massage on the human skin muscle. On the other hand, the force-based impedance control is used to control the force of the vertical direction on human skin muscle. This paper also gives the identification of human skin muscle through robot perception of impedance to decide the parameter of impedance controller. The control strategy using impedance control to implement an adaptive control system is presented, when human condition is changed with soft and hard skin muscle. Effectiveness of massage control system by using multi- fingered robot hand with hybrid impedance control is demonstrator through actual massage experiments of pushing and rubbing motion.

Liquid container transfer control on 3D transfer path by hybrid shaped approach

The paper is concerned with the advanced control of liquid container transfer, with special consideration given to the transfer on the three dimensional (3D) transfer path as well as the suppression of sloshing (liquid vibration) while maintaining a high speed of transfer for the container. The controller is designed by the hybrid shaped approach considering both time and frequency characteristics, in order to construct a high-speed transfer system for a liquid container which satisfies various control specifications such as the sloshing suppression, overshoot, settling time and restriction of control inputs magnitude. The effectiveness of the proposed control system is shown through experiments.

Expert massage motion control by multi-fingered robot hand

This paper presents a massage motion control system comprised of position control and force control in a multi-fingered robot hand. By making use of an algorithm which converted the desired fingertip trajectory into the desired angle of links in each finger by means of inverse kinematics, the finger position control from the initial position of the multi-fingered robot hand to a target position of the objects for massage was achieved. Its controller was used until the robot hand contacted the objects for massage. After contact was made, the fingertip position control was switched to a force control position needed to apply pressure for the massage. The fingertip forces exerted by an expert human therapist was measured using sheet distribution pressure sensors, and the data obtained was recorded in a computer. After the measurements were taken, the human experts fingertip force was reproduced by the robot hand. The fingertip force of the robot hand was controlled using feedback obtained with a 6-axis force sensor. To make the force of each fingertip of the four-fingered robot hand track to the fingertip force exerted by the expert human massage therapist, PI servo compensation and a Jacobian matrix were really applied for the humans shoulder. Through simulation and experiments, the usefulness of the proposed control systems was demonstrated.

Design and tension control of filament winding system

Currently a variety of fiber materials are used extensively in various fields. Carbon fiber (CF), carbon fiber reinforced plastics (CFRP) and their products are especially popular because they have higher tensile strength than metals. CFRP are generally formed by a filament-winding (FW) method. The winding pitch and tension controls of this process are key factors in making sound products. The purpose of this research is to establish an advanced filament-winding system with real-time control of the winding tension. We first describe building a filament-winding machine that can measure and control the winding tension. Second, we propose two kinds of winding tension control methods, and implement them using PID or I-PD control. Our proposed tension control methods, which make use of the rotational velocity difference between the mandrel and nip-roll parts, performed well in trials. Finally, we performed a ring burst test to check the effectiveness of tension control as it relates to product strength.