The U.S. commercial space launch industry has changed considerably since the enactment of the Commercial Space Launch Amendments Act of 2004. FAA is required to license or permit commercial space launches, but to allow the space tourism industry to develop, the act prohibited FAA from regulating crew and spaceflight participant safety before 2012—a moratorium that was later extended but will now expire on September 30, 2015. Since October 2014, there have been three mishaps involving FAA licensed or permitted launches.

美聯邦航空廳(Federal Aviation Administration)의 航空機 製作檢査 制度의 現況

An overview of the recent development of tuned vibration absorbers (TVAs) for vibration and noise suppression is presented. The paper summarizes some popular theory for analysis and optimal tuning of these devices, discusses various design configurations, and presents some contemporary applications of passive TVAs. Furthermore, the paper also presents a brief discussion on the recent progress of adaptive and semi-active TVAs along with their on-line tuning strategies, and active and hybrid fail-safe TVAs.

Passive, Adaptive and Active Tuned Vibration Absorbers—A Survey

Forcing functions are developed to produce vibration-free motions in flexible systems. These forcing functions are constructed from ramped sinusoid basis functions so as to minimize excitation in a range of frequencies surrounding the system natural frequency. Frequency domain attributes of a particular ramped sinusoid forcing function are compared with corresponding attributes of a minimum-energy optimal input and an impulse-filtered ramp signal. A closed-loop control system is developed that utilizes each of these forcing functions to generate a reference profile, and also feeds the particular forcing function forward directly to the system to enhance closed-loop bandwidth. The use of a direct feedforward signal in the closed-loop implementation results in significantly faster response times when the closed-loop bandwidth is otherwise constrained to be very low. Simulation results indicate that residual vibration has been nearly eliminated for all three forcing functions, even when some error in natural frequency exists. However, the ramped sinusoid input provides the most control over spectral energy near resonance and uses the least amount of energy to achieve vibration-free motions. >

Robust motion control of flexible systems using feedforward forcing functions

Introduction, Takashi Yamaguchi Concept of High Speed Precision Motion Control Hard Disk Drives (HDDs) Bibliography System Modeling and Identification, Hiroshi Uchida, Takashi Yamaguchi, and Hidehiko Numasato HDD Servo Systems TMR Budget Design Modeling of HDD Modeling of Disturbances and PES Bibliography Basic Approach to High Speed Precision Motion Control, Atsushi Okuyama, Takashi Yamaguchi, and Takeyori Hara Introduction to Mode Switching Control (MSC) Track-Seeking: Fast Access Servo Control Track-Settling: Initial Value Compensation (IVC) Track-Following: Single- and Multi-Rate Control Epilogue: Development of IVC Design Method in Industry Bibliography Ultra-Fast Motion Control, Mitsuo Hirata and Hiroshi Fujimoto Vibration-Minimized Trajectory Design Perfect Tracking Control (PTC) Bibliography Ultra-Precise Position Control, Takenori Atsumi, Mituso Hirata, Hiroshi Fujimoto, and Nobutaka Bando Phase-Stable Design for High Servo Bandwidth Robust Control Using H Control Theory Multi-Rate H Control Repetitive Control Acceleration Feedforward Control (AFC) Bibliography Control Design for Consumer Electronics, Mitsuo Hirata, Shinji Takakura, and Atsushi Okuyama Control System Design for Energy Efficiency Controller Design for Low Acoustic Noise Seek Servo Control Design Based on SRS Analysis Bibliography HDD Benchmark Problem, Mitsuo Hirata Public Release of the HDD Benchmark Problem Plant Model Disturbance Model Overview of the HDD Benchmark Problem Version Bibliography

High-speed precision motion control

This paper presents an experimental and analytical study of bouncing vibrations of a flying head slider in near-contact and contact regimes. In our experiment we showed that, by reducing the ambient pressure, the slider begins to touch-down and exhibit bouncing vibrations, and by increasing the ambient pressure thereafter, the slider continues to vibrate until an ambient pressure higher than the touch-down pressure. In the analysis we used a two-degrees-of-freedom slider model with linear front and rear air-bearing springs and dashpots. In a numerical simulation of slider dynamics, we considered rough surface contact of the trailing air-bearing pad with a disk, including bulk deformation, adhesion force of lubricant and friction force. The disk is assumed to have no microwaviness. From the simulation of decreasing and increasing nominal flying height, we found that the slider exhibits a bouncing vibration and touch-down/take-off hysteresis as seen in the experiment. The frequency spectrum characteristics of the bouncing vibration agree well between numerical analysis and the experiment. From a parametric study of the bouncing vibration excited by initial spacing deviation, we found that the unstable flying height range can be decreased by increasing the air-bearing stiffness and can be completely eliminated if the lubricant adhesion force or the frictional coefficient is decreased to certain small values.

Experimental and Analytical Study of Bouncing Vibrations of a Flying Head Slider in a Near-Contact Regime

Active assignment of eigenvalues and eigen-sensitivities for robust stabilization of friction-induced vibration

Multi-position ergonomic computer workstation design to increase comfort of computer work

This paper investigates the dynamics of the giant swing motions of an underactuated three-link gymnastic robot moving in a vertical plane by means of dynamic delayed feedback control (DDFC). DDFC, being one of useful methods to overcome the so-called odd number limitation in controlling a chaotic discrete-time system, is extended to control a continuous-time system such as a 3-link gymnastic robot with passive joint. Meanwhile, a way to calculate the error transfer matrix and the input matrix which are necessary for discretization is proposed, based on a Poincare section which is defined to regard the target system as a discrete-time system. Moreover, the stability of the closed-loop system by the proposed control strategy is discussed. Furthermore, some numerical simulations are presented to show the effectiveness in controlling a chaotic motion of the 3-link gymnastic robot to a periodic giant swing motion.

Dynamic delayed feedback control for stabilizing the giant swing motions of an underactuated three-link gymnastic robot

This paper describes a vibrationless access control which is robust for parameter variations. It is important for the vibrationless access control of a positioning mechanism with mechanical flexibility to eliminate residual vibration at a target position even if natural frequencies of the mechanism vary. From the relation between the residual vibration amplitude and the frequency spectrum of feedforward control force, it is found that the control force can be robust for the natural frequency variations if the control force has no frequency component within the range of varying natural frequencies. In the proposed method, an enlarged system is first constructed in the modal coordinates for a virtual mechanism which has a few natural frequencies within the varying range of the concerned natural frequency. The optimal control theory is next applied to the enlarged system and the vibrationless feedforward control force is calculated. The improved robustness of the proposed vibrationless access control is demonstrated with experimental results.

Hiroshi Yamaura

Papers

Experimental and Analytical Study of Bouncing Vibrations of a Flying Head Slider in a Near-Contact Regime

Active assignment of eigenvalues and eigen-sensitivities for robust stabilization of friction-induced vibration

Multi-position ergonomic computer workstation design to increase comfort of computer work

Dynamic delayed feedback control for stabilizing the giant swing motions of an underactuated three-link gymnastic robot

Robust Access Control for a Positioning Mechanism with Mechanical Flexibility.