Yasunao Okazaki

Development of standing-up motion assist robot to realize physiotherapist skill for muscle strength maintenance

This paper proposes a method for standing up that utilizes a patients own power to their fullest extent while allowing the person to stand up easily. Analyzing the skills of physiotherapists, we extracted two skills that we believe allowed them to assist patients in standing up by themselves: (1) promoting a forward-bending posture by making it easier to arch their backs and antevert the pelvis, and (2) providing balance so the patient does not fall down. In order to implement these skills, we propose (1) an inbuilt passive joint using a body holder to hold the patients upper body which reinforces a natural forward-bending posture, and (2) a horizontal position and vertical force assist control system which guides position control in the horizontal direction and assists with exerting force through force control in the vertical direction. We conducted experiments using linear stage system to assist with standing-up motion and confirmed that it promoted a comfortable and natural forward-bending posture through the inbuilt passive joint. Moreover, we compared standing-up motion using a control system that controls both vertical and horizontal positions with the proposed method, which guides the horizontal direction while assisting with vertical force. We found that in the position control system, when the patient performs the standing-up motion, they stand up at a predetermined constant velocity regardless of the force applied to the robot. On the other hand, the proposed method varied velocity in response to the force the patient applied to the robot. In other words, when velocity increases, the robots motion changes to apply more lifting force, and when velocity decreases, the robots motion changes to apply less lifting force. In other words, we confirmed that the system uses the patients remaining body power while assisting with standing-up motion.

Production of an atomic oxygen beam by a nozzle‐beam‐type microwave radical source

Characteristics of a nozzle‐beam‐type microwave radical source are described. This source generates microwave plasma in a space between a nozzle and a skimmer to excite a processing gas. The source has a nozzle of 0.6 mm aperture, followed by a 1.2 mm skimmer, and gases pass through the skimmer so that a molecular beam contains radicals. The total atomic oxygen flux is 1.8×1016 atoms/s at a power of 130 W and an O2 flow rate of 2 SCCM. It is possible to optimize the beam profile by varying the combination of the nozzle and the skimmer. Thus, a high‐density radical source with a compact structure and low power consumption is realized. This source is promising for oxide film growth in an ultrahigh vacuum processing.

Development and application of a nozzle‐beam‐type microwave radical source

Characteristics and application of a nozzle‐beam‐type microwave radical source are described. This source generates microwave plasma in a space between a nozzle and a skimmer for exciting a processing gas. Long‐lived metastable nitrogen molecules effective for film growth processes are observed clearly in this source. p‐type doping of ZnSe films was achieved by employing this source with N2 plasma which was installed in a molecular‐beam epitaxy system. A net acceptor concentration of 5.4×1017 cm−3 was obtained by C–V measurements with lower microwave power of 50 W and lower gas flow of 0.06 sccm compared to conventional rf plasma sources.

GENERATION OF AN ELECTRON CYCLOTRON RESONANCE PLASMA USING COAXIAL-TYPE OPEN-ENDED DIELECTRIC CAVITY WITH PERMANENT MAGNETS

A high density, uniform, and compact electron cyclotron resonance (ECR) plasma source which utilizes surface‐wave radiation and a near‐surface magnetic field is described. The microwaves propagated through a coaxial waveguide are introduced circularly into the circumferential side of a dielectric Al2O3 disk, which is placed at the open end of a coaxial‐type cavity. The ECR magnetic field is similar to three concentric planar magnetron configurations and is directed away from the dielectric surface by permanent magnets set in the center conductor of the coaxial‐type cavity. A surface wave is launched from the dielectric disk surface and generates an ECR plasma. The plasma density and electron temperature are 2.0×1011 cm−3 and 2.2 eV, respectively, at an Ar gas pressure of 10 mTorr and a microwave power of 700 W. The ion saturation current density (Isat) and its uniformity are 8.2 mA/cm2 and ±5.5% within a radius of 10 cm.

Analysis of velocity's influence on forces and muscular activity in the context of sit-to-stand motion assisted by an elderly care robot

The sit-to-stand movement is an apparently simple yet fundamental activity of daily life. Failure of performing this movement strongly impacts the quality of life of an increasing number of elderly people. Much research thus focuses on assisting this motion. The time necessary for rising up from a sit position is very short for healthy subjects, in the order of few seconds. Using similar speeds for the assisted motion would create safety concerns, hence slower speeds are usually employed. In this paper we experimentally investigate the effects of this speed reduction. We detail the relationship among robots speed, forces acting on the robots user and muscular activation. From the results of this analysis we derive indications on the speeds appropriate for assisting the sit-to-stand movement.

Numerical simulation of electron orbits in a magnetized plasma excited by a surface wave

Abstract The objective of this study is to model a surface-wave plasma (SWP) source. An additional objective is to use the simulation results to design a high–density and low–pressure operation plasma source. One of the solutions for low-pressure SWP is done in this study by applying a magnetic field. Moreover, a large dielectric disk is used for excitation and control of the surface wave. A precise and fast solution to the equation of electron motion for computer calculation is presented to predict the effects of magnetic and evanescent electric fields on plasma. A standing surface wave discharge is studied assuming that the electrical orbits in the SWP are affected by magnetic confinement and ponderomotive force. The net result is that the electrons in the static magnetic field are trapped firmly and the effects on the electron orbits by the electric field are relatively small.