1,721,212 research outputs found
Planar 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
Transmission delay analysis in heavy delayed digital systems
No full textThis paper presents a new control model, ideal for teleoperation, which takes into account the problems arising with heavily delayed communicating systems. This is done with the help of a general purpose neural network and a specific dedicated training structure which is able to train the network and to minimize the network errors due to convergence problems. The principal aim of this model is to give more stability to the data flux reducing the uncertainties due to a variable delay present in the communication suppor
Steering Marine Vehicles: a Drag Coefficient Modulation Approach
No full textThe position and orientation control of an underwater planar vehicle, actuated by rear thrusters with longitudinal control was considered in dynamic setting. The maneuvring control of the vehicle allowed the drag coefficient modulation in the sway direction. The trajectory of the marine vehicle was compared with that of the terrestrial case. It was found that the modulation function increased its action as the sway velocity increased with respect to the absolute distance
Guidelines for a Distributed Functional and Algorithmic Control Architecture for Underwater Free-flying Multi-manipulators
No full textThe paper deals with the problem of suitably coordinating the maneuvers of a non-holonomic underwater vehicle and the motion of a supported manipulation system (composed by one or two arms) when the overall system is commanded to execute a given grasping or manipulation task. Results are obtained by merging together some recent ones, relevant to the field of non-holonomic vehicle guidance and maneuvering, with those concerning the coordination of fixed base multiarm manipulation systems
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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