Constrained trajectory optimization for kinematically redundant arms

Two velocity optimization schemes for resolving redundant joint configurations are compared. The Extended Moore-Penrose Technique minimizes the joint velocities and avoids obstacles indirectly by adjoining a cost gradient to the solution. A new method can incorporate inequality constraints directly to avoid obstacles and singularities in the workspace. A four-link arm example is used to illustrate singularity avoidance while tracking desired end-effector paths

HI and Hot Gas in the Outskirts of the M81 Group

Results are presented from a wide area, high resolution HI synthesis survey of the outer regions of the nearby M81 group, where internal (galactic) and external (group-related) evolution processes can be studied simultaneously in great detail. The survey encompasses the star forming dwarf galaxies M81dwA, UGC4483, and HoII, where evidence of ram pressure stripping was recently discovered. The data do not reveal any intergalactic HI, but the outer parts of HoII are reminiscent of tidal tails. We argue however that those structures are equally consistent with the latest ram pressure models including cooling. The case for a hot intergalactic medium in this poor, spiral-only group is thus still open. The survey also puts tight constraints on possible counterparts to the local high velocity cloud population in an external group, reaching a 3 sigma column density of 10^19 atom/cm^2 and a 6 sigma limiting mass of 1.5x10^5 M_sun.Comment: 6 pages, 3 figures, to be published in "Recycling Intergalactic and Interstellar Matter," eds. P.-A. Duc, J. Braine, & E. Brinks (ASP: San Francisco

Simulating non-axisymmetric flows in disc galaxies

We present a two-step method to simulate and study non-circular motions in strongly barred galaxies. The first step is to constrain the initial parameters using a Bayesian analysis of each galaxy's azimuthally averaged rotation curve, the 3.6 $\rm \mu m$ surface brightness, and the gas surface density. The second step is to generate equilibrium models using the GalactICS code and evolve them via GADGET-2. The bar strengths and mock velocity maps of the resulting snapshots are compared to observations in order to determine the best representation of the galaxy. We test our method on the unbarred galaxy NGC 3621 and the barred galaxies NGC 1300 and NGC 1530. NGC 3621 provides a validation of our method of generating initial conditions. NGC 1530 has an intermediate bar orientation that allows for a comparison to DiskFit. Finally NGC 1300 has a bar oriented parallel to the galaxy's major axis, where other algorithms tend to fail. Our models for NGC 3621 and NGC 1530 are comparable to those obtained using commonly available algorithms. Moreover, we have produced one of the first mass distribution models for NGC 1300.Comment: 19 pages, 15 figures, 5 tables, accepted for publication in A&

An adaptive controller for enhancing operator performance during teleoperation

An adaptive controller is developed for adjusting robot arm parameters while manipulating payloads of unknown mass and inertia. The controller is tested experimentally in a master/slave configuration where the adaptive slave arm is commanded via human operator inputs from a master. Kinematically similar six-joint master and slave arms are used with the last three joints locked for simplification. After a brief initial adaptation period for the unloaded arm, the slave arm retrieves different size payloads and maneuvers them about the workspace. Comparisons are then drawn with similar tasks where the adaptation is turned off. Several simplifications of the controller dynamics are also addressed and experimentally verified

An acoustic wind measuring technique Scientific report no. 1

Technique for measuring winds using Saturn exhaust noise - acoustic technique, wind profile determined during Saturn SA-9 flight, and data reduction metho

The HI environment of the Sculptor dwarf spheroidal galaxy

New observations of the neutral hydrogen (HI) in and around the line of sight of the Sculptor dwarf spheroidal (dSph) are presented. The data obtained with the single-dish Parkes telescope cover a large area of 7\degr x 7\degr in the direction of the dwarf, and have resolutions of 15\farcm x 1.12 km/s. The Australia Telescope Compact Array (ATCA) was used to map a smaller area of 2\degr x 2\degr centered on the direction of the dwarf with higher resolutions (350\arcsec x 140\arcsec x 1.65 km/s). Many HI structures having velocities outside the range of the normal Galactic disk velocities were detected, including the two Sculptor clouds (northeast and southwest) of Carignan et al. (1998, C98). The present study shows the total extent of the C98 clouds. We derived heliocentric radial velocities for the NE and SW clouds of 100.2\pm 0.9 km/s and 105.1\pm 0.3 km/s, respectively. The intensity-weighted mean HI velocity for both clouds is 104.1\pm 0.4 km/s. The mass of each cloud is (4.1\pm 0.2) x 10^4 M_\odot (NE cloud) and (1.93\pm 0.02) x 10^5 M_\odot (SW cloud) at the Sculptor dSph distance (79 kpc).Comment: 21 pages, 7 figures, to be published in A

KAT-7 Science Verification: Using HI Observations of NGC 3109 to Understand its Kinematics and Mass Distribution

HI observations of the Magellanic-type spiral NGC 3109, obtained with the seven dish Karoo Array Telescope (KAT-7), are used to analyze its mass distribution. Our results are compared to what is obtained using VLA data. KAT-7 is the precursor of the SKA pathfinder MeerKAT, which is under construction. The short baselines and low system temperature of the telescope make it sensitive to large scale low surface brightness emission. The new observations with KAT-7 allow the measurement of the rotation curve of NGC 3109 out to 32', doubling the angular extent of existing measurements. A total HI mass of 4.6 x 10^8 Msol is derived, 40% more than what was detected by the VLA observations. The observationally motivated pseudo-isothermal dark matter (DM) halo model can reproduce very well the observed rotation curve but the cosmologically motivated NFW DM model gives a much poorer fit to the data. While having a more accurate gas distribution has reduced the discrepancy between the observed RC and the MOdified Newtonian Dynamics (MOND) models, this is done at the expense of having to use unrealistic mass-to-light ratios for the stellar disk and/or very large values for the MOND universal constant a0. Different distances or HI contents cannot reconcile MOND with the observed kinematics, in view of the small errors on those two quantities. As for many slowly rotating gas-rich galaxies studied recently, the present result for NGC 3109 continues to pose a serious challenge to the MOND theory.Comment: 25 pages, 20 figures, accepted for publication in Astronomical Journa