Dynamics and control of a spatial disorientation trainer

Abstract

Modern combat aircraft can fly at unusual orientations. The spatial disorientation trainer (SDT) examines a pilot's ability to recognise these orientations, to adapt to unusual positions and to persuade the pilot to believe in the aircraft instruments for orientation and not in his own senses. The SDT is designed as a four-degree-of-freedom (4DoF) manipulator with rotational axes. Through rotations about these axes, different orientations can be achieved; different acceleration forces acting on the pilot can also be simulated. In this paper, a control algorithm of an SDT that improves the quality and safety of the SDT motion while improving position accuracy and reducing servo errors is proposed. This control algorithm uses approximate inverse dynamics based on the recursive Newton–Euler algorithm, which accounts for the motors present in the system; it calculates motor torques, as well as the forces and moments acting on the SDT links based on the achievable velocities and accelerations of the robot links. This algorithm enables accurate dimensioning of the axes bearings and links as well. The maximum possible accelerations of the SDT links are calculated in each interpolation period based on the total moments of inertia for the axes of rotation of these links, mutual influences of the link accelerations on each other, and motor capabilities. The forces, moments and torques that act on the SDT links obtained with the suggested algorithm have lower magnitude and smoother profile. In this study, the forces and angular velocities that act on the simulator pilot in the SDT are calculated along with the roll and pitch angles of the gondola for these forces.