Chisato Kanamori

Accuracy improvement of ship mounted tracking antenna for satellite communications

Recently, data traffic for satellite communications is increasing rapidly, due to various new purposes besides the conventional voice phone and facsimile. For the reason, it is necessary to realize high frequency communications, which is to be assured by high accuracy of tracking control of an antenna. To meet the needs, this paper aims at the accuracy improvement of conventional ship mounted tracking antennas by introducing H-infinity control. In this paper, the basic characteristics of tracking antenna are investigated by experiments and the model of the antenna for controller design is established. Based on the model, an H-infinity controller is designed and implemented to the antenna. Experimental results show that the tracking accuracy can be improved to /spl plusmn/0.3 [deg], which is five times higher than that by the conventional controller.

Cooperative Operation of Two Mobile Robots

This paper describes the basic consideration and experimental results of cooperative operation of two mobile robots. First, basic concept for the cooperative operation of multiple robots and necessary functions for the system including communication function, collision avoidance and cooperative motion, are discussed. The strategy and experimental results for realizing collision-free motion between robots by communication are shown. As a typical example of cooperative operation, transporting a long pipe by two robots together is considered. To achieve higher mobility of pipe and to reduce interference between mobile robots, a new mechanism using passive joints and control algorithm for absorbing and correcting mobile errors of robots are proposed. The effectiveness of the proposed mechanism and control method is confirmed by experiments.

A rotary encoder based on magneto-optical storage

A new kind of the rotary encoder based on the magneto-optical (MO) storage is proposed. Using the MO methods, a small high-precision high-response rotary encoder can be realized. High precision is achieved by a two-stage process in which the code disk is firstly written using the direct transfer recording, and then rewritten using the corrections based on the measured errors. The systems for writing to, reading from, and evaluating the MO encoder are developed, with the optimal MO encoder reading and writing parameters determined experimentally. A trial MO encoder with a resolution of 9000 pulses/revolutions is created directly from a reference encoder, delivering an accuracy of approximately 2.8 in. The maximum resolution and response frequencies achieved are 18000 p/r and 400 kHz. After the corrected transfer recording, accuracies of 1.3 in at a resolution of 2250 p/r and 1.7 in at 9000 p/r are achieved.

Approximation of linear gain slope equalizer using Bernstein-Stancu polynomials

This paper presents a design of linear gain slope equalizer for correcting the linear gain distortion. It is based on the Bernstein-Stancu polynomials, where the well-known and readily available approximated of the desired transfer function are applied. As it is known that the Bernstein-Stancu polynomials have the several advantages. For example, there is a flexible parameter as a that can be used to adjust the magnitude response for the best result. If the parameter a equals to zero, it becomes to the classical Bernstein polynomial. In addition, the phase response is linear. As the results, the proposed method is capable of designing linear gain slope equalizer which is also shown to be efficient performance without degrading its phase characteristics. The stability of the approximated of the transfer function can guarantee with Mihailovs criterion.

Tremor suppression for handheld micromanipulator using robust hybrid control

This paper proposes a suppression of tremor effects, fluctuations caused by a users hand, on a handheld micromanipulator by means of a robust hybrid control scheme. The proposed control scheme is a combination between an explicit model predictive control and a PID controller. The advantage of the PID controller is a robustness. It is suitable for handling the holding angle changes. The explicit model predictive control provides the excellent tracking performance. In addition, the robust hybrid control can handle tremor effects successfully. The control objective is to achieve robust tracking performance, to dampen the vibration of the mechanism and to suppress a disturbance, a tremor. The experimental results are used to investigate the effectiveness of the proposed method.

Chemically assisted visualization for fluidic micro manipulation

Researchers and industrials from various fields are looking for reliable manipulators in a liquid environment. In this paper a tool for flow vitalization using chemicals to check the flows around the manipulated as well as a configuration for micro-manipulation are presented. Our research is bio-engineering oriented since we aim at manipulating a bio-target; a cell. It is challenging since these targets can be damaged easily through direct contact and are highly deformable. The successful manipulation would make the observation, selection or alteration of such targets easier, leading to great improvement in the medical and pharmaceutical fields. This paper discuss the primary challenges we face to achieve our goals. As a first step in a bigger project a first prototype was built, tested and analyzed.

Micro diagnostic by micro robot with stiffness indenter for BIO materials

The development of the instrumented indentation testing robot for bio materials with micro surface hardness and stiffness test is described. This micro surface measurement system is composed of the piezo-driven micro-robot with the indenter that can move to the measurement area precisely step by step with 1 μm per step on a metal plate and camera base coordinate measurement instruments. The position of the small robot can be controlled precisely by vision base navigation system. With the help of image processing technique, the coordination of the small robot can be identified precisely within ±10 μm resolution. Since the performance of micro hardness sensing is compared with the hardness standard block to certify its ability, the sensing head is implemented on a micro-robot. In the experiment results, the elasticity investigation with human tooth is successfully checked by the indentation load-depth characteristics.

Vibration Suppression of Ship-Mounted Antennas Using a Nonlinear Passive Vibration Isolator

We are aiming to improve the performance of a passive vibration isolator for ship-mounted antennas by designing the parameters of the isolator including nonlinear springs and dampers. It is known that a passive isolator has an inevitable problem, trade-off between minimizing the magnification of resonance and suppressing the magnifications in the region of high-frequency into lower levels. To solve this problem, we introduce a nonlinear model with more design parameters and adopt an optimization method, that is, minimizing the evaluation function consisting of two terms which indicate effects on resonant magnification and vibration isolation. By this approach, several available solutions, which can improve vibration isolation performance while with reduced magnification of resonance, are obtained.

A Coordinate Measuring Method Using Laser Plane Scanners (4th Report) - Development of 3-D Measurement System -

This paper describes a new trial system and experimental results for the three-dimensional position measurement. The principle is based on the well-known mathematical and geometric fact. It is possible to regard one point in three-dimensional space as an intersection of three planes. Then, the coordinates of it can be obtained by solving simultaneous equations of three planes. The system consists of three laser scanners, a laser detector on the target point and a computer. Each scanner is used to rotate the linearly spread laser beam called laser plane. When the detector is on the plane, each scanner to decide the equation of the plane measures the rotation angle. Ball type detector and hole type detector are developed in order to decrease the error by the incident angle. As a result of the experiment, following fact clarified. The detection range of incident angle in using the ball type is ±36 degrees. The range in using the hole type is ±60 degrees. The measurement accuracies of ±0.22mm in the small space (160mm height, 160mm width, 400mm depth) and ±0.69mm in the large space (600mm height, 600mm width, 800mm depth) are achieved. Main error factor is the coordinate error of standard point given for the calibration.

Development of High Precision Mounting Robot with Fine Motion Mechanism: Design and Control of the Fine Motion Mechanism

This chapter describes a coarse-fine robot system for the purpose of precise mounting electronic components, has been described. The development of two-axis FP and its experimental evaluation were presented. The developed fine positioner consists of piezo-electric actuator and displacement magnifying mechanism with elastic hinge. The displacement magnifying system is designed by simulation based on finite element method. Using only the control of the FP, transient and residual vibration of the coarse positioning device has been compensated successfully. As the result, high speed and precision positioning can be realized by the developed coarse-fine mounting robot system. Experimental results demonstrate significant improvements in endpoint accuracy and settling time achieved by the novel configuration of the coarse-fine robotic system.