Shape Estimation of Soft Manipulator Using Stretchable Sensor

The soft robot manipulator is attracting attention in the surgical fields with its intrinsic softness, lightness in its weight, and safety toward the human organ. However, it cannot be used widely because of its difficulty of control. To control a soft robot manipulator accurately, shape sensing is essential. This paper presents a method of estimating the shape of a soft robot manipulator by using a skin-type stretchable sensor composed of a multiwalled carbon nanotube (MWCNT) and silicone (p7670). The sensor can be easily fabricated and applied by simply attaching it to the surface of the soft manipulator. In its fabrication, MWCNT is sprayed on a teflon sheet, and liquid-state silicone is poured on it. After curing, we turn it over and cover it with another silicone layer. The sensor is fabricated with a sandwich structure to decrease the hysteresis of the sensor. After calibration and determining the relationship between the resistance of the sensor and the strain, three sensors are attached at 120° intervals. Using the obtained data, the curvature of the manipulator is calculated, and the entire shape is reconstructed. To validate its accuracy, the estimated shape is compared with the camera data. We experiment with three, six, and nine sensors attached, and the result of the error of shape estimation is compared. As a result, the minimum tip position error is approximately 8.9 mm, which corresponded to 4.45% of the total length of the manipulator when using nine sensors.

Impact Experiment and Analysis of the Carbon Fiber Composite Plate with the Central Hole

The composite material plate with the central hole is made by the composite prepreg. During the laying, the circle Teflon sheet is installed into the center of the composite plate. After curing, the center circle area was cut-out and the composite plate with the central hole was observed. Three different central holes are designed by the diameter of 12 mm, 14 mm, and 16 mm. The composite plate with central hole is stroke by the impact-or to measure the absorption energy, and acceleration to compare their impact resistance. The finite element analysis is also used to analyze the mechanical behavior of the plate during and after the impact. The results showed that the energy absorption capability is lower when the central hole became bigger.

Effect of Friction and Lubrication on Formability of AA5182 Alloy in Hydroforming of Square Cups

nfluence of friction and lubrication on formability of an aluminium alloy (AA5182) in hydroforming of square cups has been studied experimentally and numerically. Three friction conditions were created at the blank-die interface using hydraulic oil, Teflon and dry condition (no lubrication). Maximum thinning and minimum radius at the cup corners were taken as criteria for formability evaluation. Formability improved to a great extent with Teflon sheet as the lubricant. Lower friction allowed better draw-in of the material with higher uniformity of strain distribution and the maximum pressure that the material can sustain has significantly increased.

An Automated Jet Polishing Technique for Preparation of Transmission Electron Microscope Specimens for In-Situ Straining

ABSTRACTThe increasing availability of intermediate and high voltage transmission electron microscopes, together with recent improvements in video recording equipment, have led to renewed interest in in situ dynamic experiments. To alleviate the problems encountered in preparing TEM specimens with the awkward geometries required for straining stages, a jet polishing technique has been developed which allows the use of a conventional twin-jet electropolishing unit, with all its attendant advantages. A pair of Teflon sheet inserts, with rectangular openings cut to a specific shape and size, are used in the conventional specimen holder. Specimens with elliptical holes close to the center of the gauge section, and with large electron transparent areas at both ends of the long axis, are produced routinely and rapidly. Samples of many annealed metals, such as brass, molybdenum, and aluminum, prepared by this method are stronger, and can be handled more easily, than those prepared by conventional methods.

A Micro-diffusion Technique for Visualizing Nucleic Acid Molecules

Contour lengths, molecular weights, and topological parameters of single molecules of nucleic acids can be studied accurately by electron microscopy. However, specialized equipment and highly purified samples of DNA or RNA in an amount of 10-100 μgm have been required. We have developed a simple micro-diffusion technique which uses less than 0.01 (μgm of nucleic acid. Droplets containing the nucleic acid are placed on a clean teflon sheet. Cytochrome C powder is added by needle to form a monofilm. After 20-30 minutes diffusion time, there is usually enough material attached for the film to be picked up on a suitable specimen grid, shadow-cast or stained, and examined in the electron microscope. Each droplet provides material for a single observation, but experiments may be carried out contiguously on the sheet.The method has been developed for viral nucleic acids, but can also be applied to solutions of virus particles where the genomes can be released by osmotic shock or by other physical procedures. Less than 1010 particles per ml are required for this modification. Examples of nucleic acids liberated from papovaviruses, SV40, rabbit papilloma, human papilloma, and from adeno-associated satellite virus will be presented. Viral nucleic acids (DNAs from SV40 and adenovirus, RNA from bacteriophage R17) prepared by conventional techniques will also be shown.