An analysis on controlling humanoid robot arm using Robot Operating System (ROS)

Humanoid robots are extensively discussed in modern days. The movement task and manipulation of Humanoid Robots is examined based on mobility of platforms and control of the arm. This project describes a robotic arm that is analogous to an arm of a human being. Some important parameters to be considered are reachability, stability and manipulability. This thesis aims at adapting a humanoid robot arm for performing movement operation that can be used for various purposes. The proposed robot arm has 3 motors on the left arm and 3 motors on the right arm thereby constituting a total of 6 motors. This operation can be achieved by the use of sensor like ultrasonic sensor. Here Beaglebone Black, an open source linux based controller board is used. The Beaglebone Black acts as the main controller for the entire system. A research is also being made to implement the robotic arm using Robot Operating System (ROS) platform. ROS is preferred since it is modular, simple and easy to use tools for development, it provides good hardware support, lots of algorithms are implemented together as package, etc

The Globular Cluster System of the Spiral Galaxy NGC7814

We present the results of a wide-field photometric study of the globular cluster (GC) system of the edge-on Sab spiral NGC7814. This is the first spiral to be fully analyzed from our survey of the GC systems of a large sample of galaxies beyond the Local Group. NGC7814 is of particular interest because a previous study estimated that it has 500-1000 GCs, giving it the largest specific frequency (S_N) known for a spiral. Understanding this galaxy's GC system is important in terms of our understanding of the GC populations of spirals in general and has implications for the formation of massive galaxies. We observed the galaxy in BVR filters with the WIYN 3.5-m telescope, and used image classification and three-color photometry to select GC candidates. We also analyzed archival HST WFPC2 images of NGC7814, both to help quantify the contamination level of the WIYN GC candidate list and to detect GCs in the inner part of the galaxy halo. Combining HST data with high-quality ground-based images allows us to trace the entire radial extent of this galaxy's GC system and determine the total number of GCs directly through observation. We find that rather than being an especially high-S_N spiral, NGC7814 has <200 GCs and S_N ~ 1, making it comparable to the two most well-studied spirals, the Milky Way and M31. We explore the implications of these results for models of the formation of galaxies and their GC systems. The initial results from our survey suggest that the GC systems of typical ellipticals can be accounted for by the merger of two or more spirals, but that for highly-luminous ellipticals, additional physical processes may be needed.Comment: 28 pages, incl. 4 figures; accepted for publication in The Astronomical Journal, November 2003 issu

Stochastic resonance with different periodic forces in overdamped two coupled anharmonic oscillators

We study the stochastic resonance phenomenon in the overdamped two coupled anharmonic oscillators with Gaussian noise and driven by different external periodic forces. We consider (i) sine, (ii) square, (iii) symmetric saw-tooth, (iv) asymmetric saw-tooth, (v) modulus of sine and (vi) rectified sinusoidal forces. The external periodic forces and Gaussian noise term are added to one of the two state variables of the system. The effect of each force is studied separately. In the absence of noise term, when the amplitude $f$ of the applied periodic force is varied cross-well motion is realized above a critical value ($f_{\mathrm{c}}$) of $f$. This is found for all the forces except the modulus of sine and rectified sinusoidal forces.Stochastic resonance is observed in the presence of noise and periodic forces. The effect of different forces is compared. The logarithmic plot of mean residence time $\tau_{\mathrm{MR}}$ against $1/(D - D_{\mathrm{c}})$ where $D$ is the intensity of the noise and $D_{\mathrm{c}}$ is the value of $D$ at which cross-well motion is initiated shows a sharp knee-like structure for all the forces. Signal-to-noise ratio is found to be maximum at the noise intensity $D=D_{\mathrm{max}}$ at which mean residence time is half of the period of the driving force for the forces such as sine, square, symmetric saw-tooth and asymmetric saw-tooth waves. With modulus of sine wave and rectified sine wave, the $SNR$ peaks at a value of $D$ for which sum of $\tau_{MR}$ in two wells of the potential of the system is half of the period of the driving force. For the chosen values of $f$ and $\omega$, signal-to-noise ratio is found to be maximum for square wave while it is minimum for modulus of sine and rectified sinusoidal waves.Comment: 13 figures,27 page