Emerging Technology in Precision Engineering XIV

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Authors: Toshiki Hirogaki, Eiichi Aoyama, Keiji Ogawa, Takahiro Kono, Daisuke Mitsuoka
Abstract: Recently, demand has been increasing for various kinds and volumes of manufacturing systems. Also, the importance of the Automated Guided Vehicle (AGV) is increasing because it can flexibly correspond to the change of equipment in a factory. This paper describes an autonomous conveyance system for AGV based on a taxi transportation strategy. The system focuses on knowledge of a flexible taxi system in traffic engineering. A taxi is a transport unit in a traffic system with higher flexibility in traveling routes and arrival/departure points compared with railways and buses. In the present report, the waiting mode of a taxi is applied as an AGV rule and investigated to verify the effect of the proposed system. Moreover, the effect of multi-loaded AGV on system performance such as matching time and conveyance efficiency is investigated. A numerical experiment has been conducted to evaluate them. As a result, it was found that introduction of multi-loaded AGV is effective at reducing matching time without conveyance efficiency decrease.
Authors: Eiichi Aoyama, Toshiki Hirogaki, Hirohumi Kiuchi, Yoshihisa Sugiura
Abstract: Nowadays, there are the demands for application of a humanoid robot in factory automation field. There have been some reports dealing with assembling the mechanical parts. Among these, we focus on the control of percussion motion with a humanoid robot. In the present report, we propose a flexible rubber stick to control the high accurate percussion motion. To control multimodal behavior, we look at a feedback method using a sound at the percussion motion. An attempt with a humanoid robot is performed to hit the small glockenspiel with recording the sounds. We investigate the experimental results by observing the motion with a high-speed camera and a gyro sensor. As a result, it can be seen that the proposed method is effective to control the high accurate percussion motion under industrial noisy conditions.
Authors: Yuki Kobayashi, Kento Kanamori, Yuichi Imai, Ryoji Eda, Toshiyuki Horiuchi
Abstract: A small hovering robot is under development for observing circumstances in dangerous indoor spaces where human beingA small hovering robot is under development for observing circumstances in dangerous indoor spaces where human beings cannot enter. To lift and carry various mechanisms for controlling the attitude, position and level of the robot, improvements of the lifting force and payload are required without enlarging the robot size. Because the lifting force is proportional to the square of rotation speed, high-speed rotation of coaxial rotors was enabled by driving each rotor using a pair of motors, here. As a result, the lifting force and payload were drastically increased. Driving the coaxial double rotors by four motors in total, and using a high-power and long-life battery, the lifting force was increased from 4.31 N to 11.86 N, and the payload was improved from 2.84 N to 9.48 N. The flight time was limited for less than 1.5 min in the past research, because each rotor was driven by a single motor, and the motors were excessively heated by the overload. Applying the twin motor drive, the hovering time only depended on the battery capacity, and a prototype robot with 5.68 N actually hovered for more than 3 min.
Authors: Hiroshi Hamamatsu, Yasunobu Hitaka, Seiji Furuno, Takayuki Matsuo
Abstract: A high-speed, highly accurate positioning operation is required for industrial robots. However, residual vibration is generated in high-speed operation because industrial robots are cantilever structure. It takes the long settling time to the positioning operation. Acceleration feedback control is effective for vibration control. In the robot with two or more modes of vibration, the vibration mode besides targeted mode is excited by the difference of the vibration phase. In this paper, the phase relation and the vibration mode shape are clarified, and it aims at the control of the two or more modes using vibration node of the mode. The vibration modes are clarified by a modal analysis, and the vibration is controlled by the acceleration feedback. Using the vibration node of the mode stabilizes the difference of the phase of the first mode and the second mode. The effect of vibration control is verified by the experiment.
Authors: Hiroyuki Takagi, Takuya Tabata, Ken Sasaki
Abstract: Fluctuation during quiet standing of a person is one of the evaluation indexes of aging. Usually, fluctuation is measured by the center of the subject’s weight distribution on the floor, which is called center-of-pressure (COP), or the two dimensional trajectory of the top of the head taken from above the subject. In both cases, common evaluation indexes are standard deviation or maximum deviation. Control models of human quiet standing have been proposed and studied, and now it is widely accepted that human quiet standing is a nonlinear control system. However, there is no established nonlinear control model that expresses the characteristics of human quiet standing accurately. If we could express the nonlinear control dynamics of human quiet standing, the parameters of the control model can be utilized to evaluate subject’s motor control ability in more detail. In this study, we modeled the human body as a two link inverted pendulum. Leaning angle of the lower body and the upper body, and COP were measured in the experiment. Analysis of the data has revealed an asymmetry in the ankle joint torque in the anterior-posterior postural control. This asymmetry was modeled by asymmetric feedback gains of the feedback loop of ankle joint control. The proposed nonlinear model was verified by comparing the simulation results and the experimental data.
Authors: Yuki Matsuzaki, Yoichi Kadota, Kazuo Uzuka, Hideyuki Suenaga, Ken Sasaki, Takeshi Morita
Abstract: This report proposes a miniaturized non-contact actuation mechanism for a surgical device for bone extension operation. The device is embedded inside the body, and the device controls the gap between the bones cut by operation. A small permanent magnet is attached to the outer gear of a cycloidal reducer that rotates a screw of the screw-nut mechanism. This magnet is forced by the external magnetic flux density controlled by the outer permanent magnets’ position. In this research, two pairs of permanent magnet bar were rotated by stepping motors outside the device. The outer gear is constrained in As a result, ring gear of the cycloidal reducer is driven in translational wobbling motion the inner gear is connected to the screw and the output nut position is driven linearly with screw rotation. The dimensions of the fabricated device were 7 mm in diameter and 39.7 mm in length. The output thrust of this device was 2 N.
Authors: Masaya Takasaki, Shota Chino, Yasuhiro Kato, Yuji Ishino, Takeshi Mizuno
Abstract: In near-field levitation, an object can be levitated vertically upward above vibrating surface of an ultrasonic transducer. In this case, a repulsive force acts on the object. On the other hand, it has been reported that a minute object can be suspended vertically downward under the vibrating surface with a small gap in the air. We call this phenomenon ultrasonic suspension. Under the suspension, an attractive force acts on the object. When an object is suspended, there is restoring force, which pulls the object to the center of the vibrating surface. Our aim is to characterize the actuation forces under the suspension. Simultaneous measurement of vertical and horizontal actuation forces is required. A servo type measuring mechanism was proposed. A 1 DOF mechanism with a cantilever and a voice coil motor (VCM) was fabricated as a prototype. The prototype was calibrated and utilized for measurement of vertical actuation force. The result showed enough accuracy and repeatability. Then, a 2 DOF actuation force measurement mechanism was fabricated. The mechanism was consisted of a base to fix the object and two thin wires to support the base. Position of the base was controlled by three VCMs based on PID control. The ultrasonic suspension actuation forces were characterized successfully.
Authors: Ryota Okeya, Manabu Aoyagi
Abstract: Ordinal force-feedback devices mainly employ electromagnetic motors (EMMs), and are excellent at expressing springy sensations. However, it is not easy to express a realistic sense of hardness and roughness using such devices. On the other hand, an actuator system (AS) using multilayered piezoelectric actuators exhibits performance characteristics that are opposite to those of an ordinal AS using an EMM. The objective of the present study is to develop an ideal AS for a haptic display. A two-degree-of-freedom AS utilizing a pair of hybrid AS units, each consisting of an EMM, an ultrasonic motor and a piezoelectric clutch, is proposed and evaluated. Such an arrangement allows the different types of actuators to complement each other, thus compensating for their individual weaknesses. This hybrid AS can expand the range of representable sensations. The results show that the proposed AS can realistically express both hardness and softness by switching between actuator combinations.
Authors: Akihiro Torii, Mitsuhiro Nishio, Yuki Itatsu, Kae Doki, Akiteru Ueda
Abstract: A friction-free planar motor, which is composed of piezoelectric elements (piezos), is proposed. The motor is based on the principle of an inchworm using levitation mechanisms. The vertical vibration of the piezo generates the levitation force of the motor. The horizontal deformation of the piezo causes the thrust force of the motor. These piezos realizes three degree-of-freedom motion on a flat surface. We measure the displacement in the vertical and horizontal direction of the levitation mechanism. The feasibility of the inchworm using levitation mechanisms is described.
Authors: Yukio Toyozawa, Naoto Sonoda, Hiroshi Harada, Hiroshi Kashiwagi
Abstract: This paper describes a practical method to identify mechanical parameters of two-inertia mechanical system such as a linear actuator driven by a ball screw mechanism. In the proposed method, mechanical system is represented as an inverse model and a low-pass filtered M-sequence is used as an input signal. The mechanical parameters are estimated by using steepest descent method with a dead band. From the results of the computer simulation, the identified mechanical parameters quickly approach to the true mechanical parameters.

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