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Showing papers by "Asokan Thondiyath published in 2012"


Book ChapterDOI
28 Nov 2012
TL;DR: In this article, a multi-point potential field (MPPF) method for obstacle avoidance of AUVs in a 2D dynamic environment is presented, where an arc of predefined radius on a semicircle in the positive x-axis around the bow of an AUV is discretized into equiangular points with center as the current position.
Abstract: This paper presents a multi-point potential field (MPPF) method for obstacle avoidance of Autonomous Underwater Vehicles (AUV) in a 2D dynamic environment. In this method, an arc of predefined radius on a semicircle in the positive x-axis around the bow of an AUV is discretized into equiangular points with centre as the current position. By determining the point at which the minimum potential exists, the vehicle can be moved towards that point in 2D space. Here the analytical gradient of the total potential function is not calculated as it is not essentially required for moving the vehicle to the next position. The proposed obstacle avoidance algorithm is interfaced with the dynamic model of an underactuated flat-fish type AUV. The obstacle avoidance algorithm generates the path elements to the trajectory planner and the vehicle tracks the trajectory. The details of the algorithm and simulation results are presented.

17 citations


Proceedings ArticleDOI
01 Dec 2012
TL;DR: The results show that the HIL simulation is an effective tool for the verification of control algorithms and the developed obstacle avoidance algorithm can be used in real-time for the flat-fish type AUV.
Abstract: Hardware-in-the-Loop (HIL) simulations play a major role in the field of testing of Autonomous Underwater Vehicle (AUV) well before the actual vehicle is developed and deployed in the water. This paper discusses the real-time verification of a 3D obstacle avoidance algorithm of an underactuated flat-fish type AUV using hardware-in-the-loop simulation tool. Software-In-the-Loop (SIL) models are developed in MATLAB/Simulink environment and the HIL simulation is performed using dSPACE environment. The development of HIL test bench and the simulation results are presented in this paper. The results show that the HIL simulation is an effective tool for the verification of control algorithms and the developed obstacle avoidance algorithm can be used in real-time for the flat-fish type AUV.

4 citations


Proceedings Article
01 Jan 2012
TL;DR: A new approach for leader follower formation control of multi AUV systems is explored, which has the capability to compensate for initial errors and follow the leader under various operational scenarios.
Abstract: Multi robot coordination and control for underwater robots is an area of significant importance in many underwater missions. A new approach for leader follower formation control of multi AUV systems is explored in this paper. The controller estimates the next desired position of the follower robot from the past and current positions of the leader and follower robots. The control signals are then issued to the follower robot to align it to the estimated trajectory. This control scheme has the capability to compensate for initial errors and follow the leader under various operational scenarios. The development of the controller and simulation results for selected scenarios are presented. The results show that the proposed method is simple and computationally efficient.

3 citations


Journal ArticleDOI
31 Aug 2012
TL;DR: An improved guidance algorithm for autonomous underwater vehicles (AUV) in 3D space for generating smoother vehicle turn during the course change at the way-points by modified way-point guidance by the line-of-sight method.
Abstract: This paper presents an improved guidance algorithm for autonomous underwater vehicles (AUV) in 3D space for generating smoother vehicle turn during the course change at the way-points. The way-point guidance by the line-of-sight (LOS) method has been modified for correcting the reference angles to achieve minimal calculation and smoother transition at the way-points. The algorithm has two phases in which the first phase brings the vehicle to converge to a distance threshold point on the line segment connecting the first two way-points and the next phase generates an angular path with smoother transition at the way-points. Then the desired angles are calculated from the reference and correction angles. The path points are regularly parameterized in the spherical coordinates and mapped to the Cartesian coordinates. The proposed algorithm is found to be simple and can be used for real time implementation. The details of the algorithm and simulation results are presented.

2 citations


01 Jan 2012
TL;DR: In this article, a real-time HIL setup for collision avoidance of an underactuated flat-fish type AUV using dSPACE DS1104 R&D controller and ControlDesk experiment software is presented.
Abstract: Hardware-in–the-Loop (HIL) simulations play a major role in the testing and verification of underwater robots and control strategies. Not many literatures are found for the real-time HIL verification of the control algorithms for Autonomous Underwater Vehicles (AUV) in 3D space. Most of the reported real-time simulators are virtual simulators and are mainly used for visualizing the AUV motion only. Hence a HIL test set up is required well before the actual vehicle is developed and deployed in the water. This paper discusses the development of HIL setup for collision avoidance of an underactuated flat-fish type AUV using dSPACE DS1104 R&D controller and ControlDesk experiment software. The results show that the dSPACE HIL setup is an effective tool for the verification of control algorithms and the developed collision avoidance algorithm can be used in real-time for the flat-fish type AUV. By using this developed dSPACE environment, the necessary improvements and modifications can be done before actually testing the vehicle and probability of test-bed vehicle collisions with obstacles can be greatly reduced. In this way, dSPACE products and solutions provide safe and reliable evaluation.

2 citations



Book ChapterDOI
01 Jan 2012
TL;DR: An improved Media Access (MAC) layer protocol with Time Division Multiple Access (TDMA) scheduling algorithm is proposed for swarms of Autonomous underwater Vehicles (AUV) using low frequency Electromagnetic waves and the results show that there is a significant increase in the channel throughput.
Abstract: In this paper, an improved Media Access (MAC) layer protocol with Time Division Multiple Access (TDMA) scheduling algorithm is proposed for swarms of Autonomous underwater Vehicles (AUV) using low frequency Electromagnetic (EM) waves. The exchange of global variables in swarms of underwater Autonomous Vehicles (AUV) becomes very useful for many practical purposes. So a scheduling algorithm with distributive control is used to achieve the necessary many to many exchange of global variable. The knowledge of the propagation delay which is present in the system is used to overlap node communication through scheduling and thereby increase the channel utilization. Modeling and simulation of the algorithm is presented and the results show that there is a significant increase in the channel throughput.