This paper proposes a new adaptive sliding mode control scheme for achieving coordinated motion control of a group of autonomous underwater vehicles with variable added mass. The control law considers the communication constraints in the acoustic medium. A common reference frame for velocity is assigned to a virtual leader dynamically. The performances of the proposed adaptive SMC were compared with that of a passivity based controller. To save the time and traveling distance for reaching the FRP by the follower AUVs, a sliding mode controller is proposed in this paper that drives the state trajectory of the AUV into a switching surface in the state space. It is observed from the obtained results that the proposed SMC provides improved performance in terms of accurately tracking the desired trajectory within less time compared to the passivity based controller. A communication consensus is designed ensuring the transfer of information among the AUVs so that they move collectively as a group. The stability of the overall closed-loop systems are analysed using Lyapunov theory and simulation results confirmed the robustness and efficiency of proposed controller.
 J. YUH: Design and control of autonomous underwater robots: a survey. Int. J. of Control, 8(1), (2000), 7-24.
 A. NASIPURI and K. LI: A directionality based location discovery scheme for wireless sensor networks. Proc. of the 1st ACM Int. Workshop on Wireless Sensor Networks and Applications, New Yor, USA, (2002), 105-111.
 T.I. FOSSEN: Guidance and Control of Ocean Vehicles. Wiley, New York, 1994.
 E.M. SOZER, M. STOJANOVIC and J.G. PROAKIS: Underwater acoustic networks. IEEE J. of Oceanic Engineering, 25(1), (2000), 72-83.
 C. GODSIL and G. ROYLE: Algebraic Graph Theory. Springer, 2001.
 K.D. DO: Universal controllers for stabilization and tracking of underactuated ships. System & Control Letters, 47 (2002) 299-317.
 A.P. AGUIAR and J.P. HESPANHA: Trajectory-tracking and path-following of underactuated autonomous vehicles with parametric modeling uncertainty. IEEE Trans. on Automatic Control, 52(8), (2007), 1362-1379.
 W. REN and N. SORENSEN: Distributed coordination architecture for multi-robot formation control. Int. J. of Robotics and Autonomous System, 56(4), (2008), 324-333.
 R. SKJETNE, S. MOI and T. FOSSEN: Nonlinear formation control of marine craft. Proc. of the 41st IEEE Conf. on Decision and Control, bf 2 (2002), 1699-1704.
 H. BAI, M. ARCAK and J.T. WEN: Adaptive design for reference velocity recovery in motion coordination. System & Control Letters, 57(8), (2008), 602-610.
 M. ARCAK: Passivity as a design tool for group coordination. IEEE Trans. on Automatic Control, 52(8), (2007), 1380-1390.
 I.F IHLE, M. ARCAK and T.I. FOSSEN: Passivity-based designs for synchronized path-following. Automatica, 43(9), (2007), 1508-1518.
 Y. WANG, W. YAN and J. LI: Passivity-based formation control of autonomous underwater vehicles. IET Control Theory & Applications, 6(4), (2012), 518-525.
 W. WANG, J. YI and D. LIU: Design of a stable sliding-mode controller for a class of second-order underactuated system. IEE Proc. of Control Theory and Application, 151(6), (2004), 691-698.
 J. CHENG, J. YI and D. ZHAO: Design of a sliding mode controller for trajectory tracking problem of marine vessels. IET Control Theory & Applications, 1(1), (2007), 233-237.
 R. GHABCHELOO, A. AGUIAR, A. PASCOAL, C. SILVESTRE, I. KAMINER and J. HESPANHA: Coordinated path-following control of multiple underactuated autonomous vehicles in the presence of communication failures. Proc. of the 45th IEEE Conf. on Decision and Control, (2006), 4345-4350.
 B. SUBUDHI and S.S. GE: Sliding-mode-observer-based adaptive slip ratio control for electric and hybrid vehicles. IEEE Trans. on Intelligent Transportation Systems, 13(4), (2012), 1617-1626.
 P. MILLAN, L. ORIHUELA, I. JURADO and F.R. RUBIO: Formation control of autonomous underwater vehicles subject to communication delays. IEEE Trans. on Control Systems Technology, 22(2), (2014), 770-777.
 D. ANGELI and E. MOSCA: Lyapunov-based switching supervisory control of nonlinear uncertain systems. IEEE Trans. on Automatic Control, 47(3), (2002), 500-505.
 C.J.F. SILVESTRE: Multi-Objective Optimization Theory with Applications to the Integrated Design of Controllers/Plants for Autonomous Vehicles. Ph.D Thesis, Technical Institute of Lisbon, Jun. 2000.
 Z. HU, C. MA, L. ZHANG and A. HALME: Distributed formation control of autonomous underwater vehicles with impulsive information exchanges and disturbances under fixed and switching topologies. Proc. of 23rd IEEE Int. Symp. on Industrial Electronics, (2014), 99-104.
 Y. CAO andW. REN: Distributed coordinated tracking with reduced interaction via a variable structure approach. IEEE Trans. on Automatic Control, 57(1), (2012), 33-48.