AUTHORS: Jerzy Garus
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ABSTRACT: The paper concentrates on a problem of distributing control effort among multiple, redundant actuators in a propulsion system of a small torpedo-shaped unmanned underwater vehicle. The vehicle has no other actuators except thrusters so motion and positioning is realised only by change of their developed thrusts. The control allocation strategy used to map desired forces and torques to thrusts on all actuators is defined as an unconstrained model based optimisation problem. Such a solution is computationally efficiently but, in real conditions, when physical limitations are not taken into account it may be unrealized and cause temporarily loss of vehicle’s controllability. To avoid a such situation a procedure of checking of capability of the propulsion system to produce demanded generalized forces is proposed to be introduced to the process of power distribution. The procedure, taking into account actuators constraints, allows to find such values of the generalized forces for which the distribution can be done correctly. To illustrate the proposed method a numerical example is given in the work.
KEYWORDS: Over-actuated underwater vehicle, control system, thrust allocation, optimisation
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