1,721,037 research outputs found
Nonlinear time-invariant feedback control of an underactuated marine vehicle along a straight course
No full textPlanar Motion Steering of Underwater Vehicles by Exploiting Drag Coefficient Modulation
No full textPlanar motion steering of underwater vehicles was studied by exploiting drag coefficient modulation. Modulation of longitudinal control surfaces resulted in suitability of controlling the sway velocity for the asymptotic convergence toward the desired final position and attitude of the vehicle. Simulation results compared with purely kinematics case showed the effectiveness of the proposed dynamic control technique
Closed Loop Control of 3D Underactuated Vehicles via Velocity Field Tracking
No full textA novel strategy to design time invariant motion controllers for underactuated mobile systems is applied to the position and attitude control of an underactuated 3D vehicle. The idea consists in defining a velocity vector field such that an ideal, fully actuated system would exponentially achieve the control objective by simply following such field. Then a steering law for the given underactuated system is designed such that it is exponentially stabilized parallel to the above mentioned velocity vector field. For the particular problem here addressed, due to the use of polar like coordinates, this method yields a discontinuous control law. Both the design process and the resulting solution have a most clear physical interpretation. Important practical requirements as approaching the target on a null curvature path, avoiding cusps in the whole path and moving in only one given forward direction are easily satisfied within this framework
Robust global stabilization of an Underactuated marine vehicle on a linear course by smooth time-invariant feedback
No full textThe stabilization of an underactuated marine vehicle on a linear course is considered. In spite of being controllable and that Brocketts Theorem does not prevent the existence of a smooth pure feedback control solution, standard tools of nonlinear control as feedback linearization cannot be applied. A smooth, time invariant, globally converging control solution is designed on the basis of a simple and novel idea to derive motion control laws for underactuated systems. Robustness with respect to model parameter uncertainty and state measurement errors is discussed both analytically and through simulations
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