James, Kurian; Subramaniam, M P; Saseendran Pillai, P R(IEEE, September 22, 2003)
[+]
[-]
Abstract:
For the scientific and commercial utilization of Ocean resources, the role of
intelligent underwater robotic systems are of great importance. Scientific activities like
Marine Bio-technology, Hydrographic mapping, and commercial applications like Marine
mining, Ocean energy, fishing, aquaculture, cable laying and pipe lining are a few utilization
of ocean resources. As most of the deep undersea exploration are beyond the reachability of
divers and also as the use of operator controlled and teleoperated Remotely Operated Vehicles (ROVs)
and Diver Transport Vehicles (DTVs) turn out to be
highly inefficient, it is essential to have a fully
automated system capable providing stable control
and communication links for the unstructured
undersea environment.
A new localization approach to increase the navigational
capabilities and object manipulation of autonomous
mobile robots, based on an encoded infrared sheet of light
beacon system, which provides position errors smaller than
0.02m is presented in this paper. To achieve this minimal
position error, a resolution enhancement technique has
been developed by utilising an inbuilt odometric/optical
flow sensor information. This system respects strong low
cost constraints by using an innovative assembly for the
digitally encoded infrared transmitter. For better guidance
of mobile robot vehicles, an online traffic signalling capability
is also incorporated. Other added features are its less
computational complexity and online localization capability
all these without any estimation uncertainty. The
constructional details, experimental results and computational
methodologies of the system are also described
Description:
Journal of Automation, Mobile Robotics & Intelligent Systems VOLUME 3, N° 2 2009
James, Kurian; Saseendran Pillai, P R(December 8, 2008)
[+]
[-]
Abstract:
This paper introduces a simple and efficient method
and its implementation in an FPGA for reducing the odometric
localization errors caused by over count readings of an
optical encoder based odometric system in a mobile robot
due to wheel-slippage and terrain irregularities. The detection
and correction is based on redundant encoder measurements.
The method suggested relies on the fact that the
wheel slippage or terrain irregularities cause more count
readings from the encoder than what corresponds to the
actual distance travelled by the vehicle. The standard quadrature
technique is used to obtain four counts in each encoder
period. In this work a three-wheeled mobile robot
vehicle with one driving-steering wheel and two-fixed rear
wheels in-axis, fitted with incremental optical encoders is
considered. The CORDIC algorithm has been used for the
computation of sine and cosine terms in the update equations.
The results presented demonstrate the effectiveness
of the technique
Description:
Journal of Automation, Mobile Robotics & Intelligent Systems VOLUME 3, No 3 2009
James, Kurian; Balakrishnan, K G; Nair, K G(IOP Publishing LTD, August 19, 1992)
[+]
[-]
Abstract:
A simple and inexpensive power supply suitable for characteristics
studies of a klystron is described. The circuit is a modified form of the high voltage
adjustable power supply based on LM 317. This provides the necessary cavity and
repeller voltages over a wide range, with good regulation. The system is protected
aa- ainst short circuits and is ideallv suitable for laboratorv, ex.Deri ments with reflex
klystrons.