A dynamic tactile sensor on photoelastic effect

Certain photoelastic materials exhibit birefringent characteristics at a very low level of strain. This property of material may be suitable for dynamic or wave propagation studies, which can be exploited for designing tactile sensors. This paper presents the design, construction and testing of a novel dynamic sensor based on photoelastic effect, which is capable of detecting object slip as well as providing normal force information. The paper investigates the mechanics of object slip, and develops an approximate model of the sensor. This allows visualization of various parameters involved in the sensor design. The model also explains design improvements necessary to obtain continuous signal during object slip. The developed sensor has been compared with other existing sensors and experimental results from the sensor have been discussed. The sensor is calibrated for normal force which is in addition to the dynamic signal that it provides from the same contact location. The sensor has a simple design and is of a small size allowing it to be incorporated into robotic fingers, and it provides output signals which are largely unaffected by external disturbances

Beyond LISA: Exploring Future Gravitational Wave Missions

The Advanced Laser Interferometer Antenna (ALIA) and the Big Bang Observer (BBO) have been proposed as follow on missions to the Laser Interferometer Space Antenna (LISA). Here we study the capabilities of these observatories, and how they relate to the science goals of the missions. We find that the Advanced Laser Interferometer Antenna in Stereo (ALIAS), our proposed extension to the ALIA mission, will go considerably further toward meeting ALIA's main scientific goal of studying intermediate mass black holes. We also compare the capabilities of LISA to a related extension of the LISA mission, the Laser Interferometer Space Antenna in Stereo (LISAS). Additionally, we find that the initial deployment phase of the BBO would be sufficient to address the BBO's key scientific goal of detecting the Gravitational Wave Background, while still providing detailed information about foreground sources.Comment: 9 pages, 10 figures, published versio

My Diary in December, January, and February in Japan

Postcard from Steven Crowder, during the Linfield College Year Abroad Program at Rikkyo University in Tokyo, Japa

Month of Trials

Postcard from Steven Crowder, during the Linfield College Year Abroad Program at Rikkyo University in Tokyo, Japa

Designing a dexterous reconfigurable packaging system for flexible automation

This paper presents a design for a reconfigurable packaging system that can handle cartons of different shape and sizes and is amenable to ever changing demands of packaging industries for perfumery and cosmetic products. The system takes structure of a multi-fingered robot hand, which can provide fine motions, and dexterous manipulation capability that may be required in a typical packaging-assembly line. The paper outlines advanced modeling and simulation undertaken to design the packaging system and discusses the experimental work carried out. The new packaging system is based on the principle of reconfigurability, that shows adaptability to simple as well as complex carton geometry. The rationale of developing such a system is presented with description of its human equivalent. The hardware and software implementations are also discussed together with directions for future research

Photoelasticity based dynamic tactile sensor

The paper presents design, construction and testing of a photoelasticity based dynamic sensor which is capable of detecting slip as well as providing normal force information. Starting with investigations into mechanism of slip, an approximate model of the sensor has been developed. This model explains the design improvements necessary to provide continuous signal during slip. The theoretical model also helps identify various sensor parameters to characterize the sensor. The developed sensor has been compared with other existing sensors and the experimental results from the sensor have been discussed for the type of signal the sensor provides. The sensor is also calibrated for normal force. The sensor is novel in the sense that it offers dynamic slip signal as well as the normal force information from a single contact location, it provides continuous signal during slip, and it has small size which can be easily incorporated into robotic fingers. The sensor has an edge over other existing sensors that its design is simple yet it provides strong signals which are largely unaffected by external disturbances. Copyright © 2005 by ASME

Simulated propeller slipstream effects on a supercritical wing

To quantify the installed performance of high speed (M = 0.8) turboprop propulsion systems, an experimental program designed to assess the magnitude of the aerodynamic interference of a propeller slipstream on a supercritical wing has been conducted. The test was conducted in the NASA Ames 14-foot wind tunnel. An ejector-nacelle propeller slipstream simulator was used to produce a slipstream with characteristics typical of advanced propellers presently being investigated. A supercritical wing-body configuration was used to evaluate the interference effects. A traversing total pressure rake was used to make flow field measurements behind the wing and to calibrate the slipstream simulator. The force results indicated that the interference drag amounted to an increase of ten counts or about 3% of the wing-body drag for a two engine configuration at the nominal propeller operating conditions. However, at the higher swirl angles (11 deg vs. 7 deg nominally) the interference drag was favorable by about the same magnitude