Arm-Helicopter Control with Positive Signals

In this paper a control algorithm is proposed, which provides positive signals to the propeller inputs of a 3 degrees of freedom arm-helicopter system, in consequence the propellers spin only in one direction. The originality of this paper in reference to similar papers, is the fact that preview control algorithms are designed to allow propeller spin in both directions, that bring to the helicopter system a movement acting in the same direction of gravitation force, in practical sense this never happens, because the helicopter system presents an unstable behavior. The proposed algorithm regulates the system angular position using information of angular displacements measurements to generate only positive control signals, and also compensates the unknown friction effects present in the joints of the system. The performance of the algorithm is evaluated using numerical tests, which shows the system stability considering the regulation problem of two degrees of freedom, in the same sense a stability argumentation is presented to validate the control algorithm proposed.