Hung-Yao Hsu

Development of a contact probe incorporating a Bragg grating strain sensor for nano coordinate measuring machines

This paper presents a novel optical fibre based micro contact probe system with high sensitivity and repeatability. In this optical fibre probe with a fused spherical tip, a fibre Bragg grating has been utilized as a strain sensor in the probe stem. When the probe tip contacts the surface of the part, a strain will be induced along the probe stem and will produce a Bragg wavelength shift. The contact signal can be issued once the wavelength shift signal is produced and demodulated. With the fibre grating sensor element integrated into the probe directly, the probe system shows a high sensitivity. In this work, the strain distributions along the probe stem with the probe under axial and lateral load are analysed. A simulation of the strain distribution was performed using the finite element package ANSYS 11. Performance tests using a piezoelectric transducer stage with a displacement resolution of 1.5 nm yielded a measurement resolution of 60 nm under axial loading.

A faster path planner using accelerated particle swarm optimization

The idea of placing small mobile robots to move around in a large building to detect potential intruders has been around for some time. However, there are still two major hurdles to overcome: to locate itself in the environment and to make a decision on how to move around safely and effectively at a reasonable computation cost. This paper describes a mathematical model for developing a scheme for an autonomous low cost mobile robot system using visual simultaneous localization and mapping and accelerated particle swarm intelligent path planner. The results indicated that this system could provide a solution for the problem of indoor mobile robot navigation. Advances in computer technology make this technique a cost effective solution for a future home service robot.

A CFD-aided experimental study on bending of micro glass pipettes

This paper presents a study on the temperature profile in the bending process of glass pipettes. To prevent undesirable deformation of the pipette at its bending section, such as kink and constriction, several factors influencing the bending quality are investigated, including the width and temperature of the heating element, heating and bending time. Taguchi method is used to study the key factors and to identify an optimal parameter combination. ANSYS is also employed to study the heat transfer and temperature distribution in the heating zone. It is concluded that the temperature distribution in the bending area is critical to the bending quality, and the width of the heating element decisively determines the temperature distribution.

Use of a cold mirror system for citrus fruit identification

This paper presents a portable multispectral data acquisition system for extending part of citrus fruit imaging and measurement purpose. An economic mechanic based fixture has been made to position and align a classical cold mirror and two CCD cameras in relative kinematic position. With optocoupler interface, two cameras have been synchronized to capture the images at the same view to acquire certain spectral area from the visible to the near infrared area based on the cold mirror function. To register both images from two cameras, the software based self calibration has been done to estimate the precision of two cameras position relative to the 3D object pattern frame via the cold mirror. The issues regarding the calibration and the distortion produced by the lens on real images have been discussed. The calibration result from the bi-camera system achieved averagely no more than 2 pixels misalignment error corresponding to less than 8 micrometer with non-uniform error distribution on the whole image. The real time fruit citrus images from both cameras have been segmented to estimate the misalignment error to select the well aligned images for the study.

Smart thin-film piezoelectric composite sensors based on high lead zirconate titanate content

Piezoelectric composites are hybrid materials primarily consisting of polymer matrices and micro-sized particles of ferroelectric ceramic. While incorporating high-fraction ceramic particles into composites is indispensable to meet the ever increasing requirement of sensitivity, it is a great challenge to achieve such a high concentration due to processing difficulties. In this study, we developed piezoelectric composites of 0-3 geometry containing 95 wt% (∼73 vol%) lead zirconate titanate particles by modifying the surface of lead zirconate titanate particles with isophorone diisocyanate and polyoxyalkyleneamine (J2000) and compounding them with epoxy resin. The functional groups of J2000 molecules covalently grafted onto the particle surface can react with the matrix, thus creating a robust linkage between the matrix and the particles. This improved the particle dispersion and the interface, enabling the development of a superior composite film with high lead zirconate titanate fractions. Modified piezocomposites can save up to 75% poling time at 75% lower voltage in comparison with the unmodified sample as well as previous studies. The remarkable improvement is indebted to the two-stage interface modification process and the layer-by-layer fabrication method.

Bearing Retainer Designs and Retainer Instability Failures in Spacecraft Moving Mechanical Systems

Bearing retainer instability is one of the major causes of failure in the ball bearings used in spacecraft systems. These bearing failures lead to mission failure or performance degradation of the spacecraft. The instability is characterized by intermittent torque fluctuations and severe audible noise in both low- and high-speed bearings. It also generates severe transient forces that result in high cage wear or fracture. A series of retainer designs was made and the possibility of instability under various operating conditions of a momentum/reaction wheel used in a spacecraft was studied. Various tests such as run-in test, temperature test, and overlubrication test were conducted to study the instability and select a design that is stable under all operating conditions. The study results showed that square pocket retainers are more stable compared to circular pocket retainers.

A proposal on development of intelligent PSO based path planning and image based obstacle avoidance for real multi agents robotics system application

This is a proposal on combination of PSO based path planning by using data from odometry and on-board camera image based obstacle avoidance for real time multi-agents robotics system application. This is a system which is a robust yet low cost centralized control multi-agent system for various application especially indoor surveillance systems. PSO will help the robots to move towards the target and at the same time avoiding the obstacle.

Development of a Centrifugal Oil Lubricator for Long-Term Lubrication of Spacecraft Attitude Control Systems—Experimental Evaluation

The success of a spacecraft mission depends to a great extent on the performance of the moving mechanical systems. The most common mode of failure in these systems is tribological. Tribological failures occur mainly due to nonavailability of lubricant at the working zone of the bearings as a result of degradation, evaporation, and creep. The life of these moving mechanical systems could be extended if lubricant is replenished by some means. Therefore, to ensure long-term uninterrupted performance of these systems, an efficient lubricant replenishment system is essential. This article describes the development of a novel lubricant supply system that can supply lubricant for more than 30 years at a controlled rate of a few micrograms/hour. Experimental evaluation of the lubricator was carried out under different operating conditions experienced in a spacecraft. The results of the experiments are compared with the theoretical results obtained from the mathematical model and computational fluid dynamics (CFD) simulation. The lowest flow rate obtained was 3.5 μg/h from a lubricator with a flow control orifice diameter of 2.3 μm. The results of the study show that the lubricator can provide a long-term uninterrupted supply of lubricant to the moving mechanical systems for a period of more than 30 years. An outstanding and most promising feature of this lubricator is that the flow rate at various stages of the life can be theoretically predicted using the developed mathematical model and the prediction can be experimentally verified before the system is put into service.

Autonomous mobile robot system concept based On PSO path planner and vSLAM

The idea of placing small mobile robots to move around in a large building for potential intruders detection has been aroused for some time. However it is still facing two major hurdles: not to lose its ground truth and to make a decision on how to move around safely and effectively within reasonable computation cost. This paper describes a mathematical model for a development of a scheme for an autonomous low cost mobile robot system using visual SLAM (simultaneous localisation and mapping) and Particle Swarm Intelligent path planner. The result showed that this system could provide a solution for the problem in indoor mobile robot navigation. The advancements of the computer technology make this technique as a cost effective solution for a future home service robot.

Concept design of a novel tactile probe tip for down scaled 3D CMMs

Although coordinate metrology has reached a very high state of development concerning versatility and accuracy for common engineering parts, a high precision capability with nano scale resolution and accuracy is often hard to achieve when it is required to measure very small parts and features. The limiting component is the bulky probing system of traditional CMMs (coordinate measuring machines). In order to satisfy increasing demand for highly accurate geometrical measurements on small parts and small structures, a new measuring probe of high sensitivity and small geometrical dimension with low contact forces needs to be developed. In this paper, a novel probing system, which combines a FBG (Fibre Bragg Grating) embedded optical fibre tactile probe with an optical sensing technique, has been proposed. With the sensor elements integrated into the probe tip directly, the system sensitivity can be increased significantly. A preliminary theoretical analysis of the sensitivity of the FBG fibre sensor under axial and lateral end point loading has been presented and the results show that this micro scale probe has great potential to realize a resolution of 1nanometer on geometrical measurement of small parts.