Microcomputer Aided Selection Of Robot Manipulators

This paper presents two programs for microcomputer aided assessment of the performance of robot manipulators. The first program automatically generates robot models based on user-supplied kinematic parameters. The program also derives a kinematic model that relates the motion of manipulator end-effector to the motion of the joints using the inverse kinematic approach. The approach uses a robust inversion technique that can handle singular conditions as well as joint redundancy. A user can optionally select evaluation of kinematic capabilities of the robot manipulator, such as the ability of the end-effector to reach a specified position and orientation in space or the evaluation of the work space. The second program generates dynamic variables, such as forces and torques, based on user-supplied dynamic parameters and equations of motion of the various joints. Both programs are written for implementation on personal computers. Several runs were carried out to demonstrate the capability and execution times of the two program

Self-learning Kinetic Monte-Carlo method: application to Cu(111)

We present a novel way of performing kinetic Monte Carlo simulations which does not require an {\it a priori} list of diffusion processes and their associated energetics and reaction rates. Rather, at any time during the simulation, energetics for all possible (single or multi-atom) processes, within a specific interaction range, are either computed accurately using a saddle point search procedure, or retrieved from a database in which previously encountered processes are stored. This self-learning procedure enhances the speed of the simulations along with a substantial gain in reliability because of the inclusion of many-particle processes. Accompanying results from the application of the method to the case of two-dimensional Cu adatom-cluster diffusion and coalescence on Cu(111) with detailed statistics of involved atomistic processes and contributing diffusion coefficients attest to the suitability of the method for the purpose.Comment: 18 pages, 9 figure

HAPS Gateway Link in the 5850-7075 MHz and Coexistence with Fixed Satellite Service

Gateway link is essential to connect HAPS platform to terrestrial based networks. This crucial link is incorporated in HAPS fixed service spectrum allocation in considerably high frequencies, renders the link for more attenuations by atmospheric gases, and rain effects, especially when the regional climate is not favorable. However, under the agenda item 1.20 of World Radio Conference-2012 (WRC-12) new HAPS allocation in the 5850-7075 MHz band is proposed. Although, spectrum features are incomparably reliable, on the contrary, Fixed Satellite Service (FSS) uplink transmissions will have signal levels much higher than those in HAPS systems and have the potential for causing interference at the HAPS gateway receiver. In this article a key aspect of co-channel interference phenomena is investigated to facilitate optimum frequency sharing in the band in question. By proposing mitigation techniques and statistical method this generic prediction model enhances the capability of the HAPS spectrum sharing and provides flexibility in spectrum planning for different fixed services

Optical pathlength control on the JPL Phase B interferometer testbed

Design and implementation of a controller for optical pathlength compensation on a flexible structure is presented. Nanometer level pathlength control is demonstrated in the laboratory. The experimental results are in close agreement with performance predictions