A controllably adhesive climbing robot using magnetorheological fluid

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2012.Cataloged from PDF version of thesis.Includes bibliographical references (p. 67-69).In this thesis, the novel adhesive effects of magnetorheological fluid for use in climbing robotics were experimentally measured and compared to existing cohesive failure fluid models of yield stress adhesion. These models were found to correlate with experimental results at yield stresses below 1.12 kPa. MR fluid samples activated to have yield stresses above 1.12 kPa were limited to an adhesive stress of approximately 25-30 kPa regardless of inital fluid thickness or yield stress. A climbing robot capable of utilizing MR fluid adhesion was constructed and shown to be capable of adhering to surfaces of any orientation and climbing rough surfaces with a 45° slope. The robot was capable of controllably adhering to rough sandpaper and smooth glass with an adhesive stress of 7.3 kPa, demonstrating a novel form of adhesion on a wide range of surface roughnesses and orientations.by Nicholas Eric Wiltsie.S.M

Terrain Traversing Device Having a Wheel with Microhooks

A terrain traversing device is described. The device includes an annular rotor element with a plurality of co-planar microspine hooks arranged on the periphery of the annular rotor element. Each microspine hook has an independently flexible suspension configuration that permits the microspine hook to initially engage an irregularity in a terrain surface at a preset initial engagement angle and subsequently engage the irregularity with a continuously varying engagement angle when the annular rotor element is rotated for urging the terrain traversing device to traverse a terrain surface. Improvements related to the design, fabrication and use of the microspine hooks in the device are also described

Biblade Sampler

A BiBlade sampler may include a first blade and a second blade in a retracted position. The BiBlade sampler may also include a gripper, which is driven by an actuator. The gripper may include a plurality of fingers to force the first blade and the second blade to remain in a retracted position. When the fingers are unhooked, the first blade and the second blade penetrate a surface of an object

Characterization of an SVA for use in rehabilitative robotics

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2010.Cataloged from PDF version of thesis.In this thesis, a series viscous actuator, composed of a viscous rotary damper connected to the output of a geared electric motor, is proposed as a novel solution to the high actuator impedances encountered when using such a motor. High impedances can be undesirable when interacting with the environment or animal subjects as unexpected forces may damage already-compromised joints. A state space model for the series viscous actuator was derived and verified by measurements upon a physical system. Physical design considerations for implementing a series viscous actuator, such as the appropriate gearing ratio and damper selection, are discussed and supported using the derived model.by Nicholas Eric Wiltsie.S.B

A robotic approach to mapping post-eruptive volcanic fissure conduits

VolcanoBot was developed to map volcanic vents and their underlying conduit systems, which are rarely preserved and generally inaccessible to human exploration. It uses a PrimeSense Carmine 1.09 sensor for mapping and carries an IR temperature sensor, analog distance sensor, and an inertial measurement unit (IMU) inside a protective shell. The first field test succeeded in collecting valuable scientific data but revealed several needed improvements, including more rugged cable connections and mechanical couplers, increased ground clearance, and higher-torque motors for uphill mobility. The second field test significantly improved on all of these aspects but it traded electrical ruggedness for reduced data collection speed. Data collected by the VolcanoBots, while intermittent, yield the first insights into the cm-scale geometry of volcanic fissures at depths of up to 25 m. VolcanoBot was deployed at the 1969 Mauna Ulu fissure system on Kīlauea volcano in Hawai'i. It collected first-of-its-kind data from inside the fissure system. We hypothesized that 1) fissure sinuosity should decrease with depth, 2) irregularity should be persistent with depth, 3) any blockages in the conduit should occur at the narrowest points, and 4) the fissure should narrow with depth until it is too narrow for VolcanoBot to pass or is plugged with solidified lava. Our field campaigns did not span enough lateral or vertical area to test sinuosity. The preliminary data indicate that 1) there were many irregularities along fissures at depth, 2) blockages occurred, but not at obviously narrow locations, and 3) the conduit width remained a consistent 0.4–0.5 m for most of the upper 10 m that we analyzed

Antibacterial small molecules targeting the conserved TOPRIM domain of DNA gyrase

<div><p>To combat the threat of antibiotic-resistant Gram-negative bacteria, novel agents that circumvent established resistance mechanisms are urgently needed. Our approach was to focus first on identifying bioactive small molecules followed by chemical lead prioritization and target identification. Within this annotated library of bioactives, we identified a small molecule with activity against efflux-deficient <i>Escherichia coli</i> and other sensitized Gram-negatives. Further studies suggested that this compound inhibited DNA replication and selection for resistance identified mutations in a subunit of <i>E</i>. <i>coli</i> DNA gyrase, a type II topoisomerase. Our initial compound demonstrated weak inhibition of DNA gyrase activity while optimized compounds demonstrated significantly improved inhibition of <i>E</i>. <i>coli</i> and <i>Pseudomonas aeruginosa</i> DNA gyrase and caused cleaved complex stabilization, a hallmark of certain bactericidal DNA gyrase inhibitors. Amino acid substitutions conferring resistance to this new class of DNA gyrase inhibitors reside exclusively in the TOPRIM domain of GyrB and are not associated with resistance to the fluoroquinolones, suggesting a novel binding site for a gyrase inhibitor.</p></div

Mapping of the MRL-770/423/1082 resistance mutations onto a model of <i>E</i>. <i>coli</i> DNA gyrase (GyrBA fusion dimer) suggests a novel inhibitor interaction domain.

<p>Amino acids in the GyrB domain (light blue) where MRL-770/MRL-423 resistant primary mutations reside are rendered in stick form. The GyrA domains of monomers 1 and 2 are colored in light green and green respectively, S83 and N87 of GyrA monomer 1 are shown in stick form. The two ciprofloxacin molecules are displayed in CPK and carbon atoms colored in yellow. Nicked DNA is shown in orange and Mn⁺² ions are in purple.</p

Antibacterial small molecules targeting the conserved TOPRIM domain of DNA gyrase - Fig 3

<p><b>Dose-dependent inhibition of <i>E</i>. <i>coli</i> (A) and <i>P</i>. <i>aeruginosa</i> (B) DNA gyrase by MRL-423 and MRL-1082 respectively</b>. (C) Dose-dependent stabilization of cleavage complex formation in <i>E</i>. <i>coli</i> DNA gyrase by MRL-423. Relaxed, closed circular substrate (rel.), linear (lin.), and super-coiled (sc.) DNA species are indicated to the left of each gel image.</p

Chemical structures of novel DNA gyrase inhibitors and reference compounds.

<p>Chemical structures of novel DNA gyrase inhibitors and reference compounds.</p