Showing papers by "Asokan Thondiyath published in 2016"

Design and Analysis of Cascaded Variable Buoyancy Systems for Selective Underwater Deployment

Abstract: Variable Buoyancy systems for selective deployment has been designed and the analysis of dynamics is discussed in this paper. Multiple interconnected VB modules have specific advantages in positioning the payloads like sensors and communication equipment at various depths to collect strategically important subsea data. The design of metallic bellow based Variable Buoyancy Systems (VBS) is presented along with the dynamic analysis of the module. The dimensions of the VB module are optimised to give best performance at the desired depth of operation. Effect of anchoring the module to a base station and cascading multiple modules for deploying at various depths have been studied in detail. Simulation results show that the cascaded VB modules can be successfully deployed for selective applications under various operating conditions.

Stability Analysis of Haptic Virtual Environment Systems for Active Interactions in Surgical Robot Simulators

Abstract: A haptic interface is a link between a human operator and a virtual environment and conveys a kinesthetic sense of presence in the virtual environment to the operator. The combined system includes a virtual environment simulated in a digital computer, a human operator and a haptic display that are actual physical systems. Such interfaces are commonly used in tele-surgical simulators and other systems to get a better feel for the user. For this system, stability is a prime concern because it may be affected by three major factors that are communication delay, controller discretization, and active operator intervention. In this paper, the stability of these systems is analysed and a framework which allows operator to interact actively with the virtual environment is proposed for telesurgical applications using surgical robots. Study of the simultaneous effect of all three de-stabilizing factors are carried out via the proposed framework. The well-known Colgate’s stability condition for a 1-user haptic system with a passive operator is reproduced and then extended to the case which allows each operator to behave actively. Another extension to Colgate’s condition comes by allowing communication delays to exist in the system. Simulations confirm the validity of the proposed conditions for stability of sampled-data Haptic Virtual Environment (HVE) systems.