Patent ID: 8190307
Filing Date: 2012-05-29
Classification: G05D,Y10S

Abstract:
1. A control optimization method for a helicopter carrying a suspended load while in hover flight, the method comprising the steps of: designing a helicopter attitude and position tracking controller, the helicopter attitude and position tracking controller generating outputs for stabilizing the helicopter while accepting tracking commands from a reference source and displacement commands from a feedback source as inputs, the design including feedback gain (k) based on minimizing a load swing history, wherein the load swing history is represented by a Linear Quadratic Regulator method, the Linear Quadratic Regulator method depending on minimizing the quadratic function: wherein indx represents the feedback gain matrix integral over time tf, wherein η τ and η represent helicopter control inputs, wherein .e τ represents an error signal, wherein Qe represents an angular velocity of a helicopter, and wherein R is a position vector of the load with respect to a center of mass of the helicopter; determining helicopter dynamics, suspended load forces and suspended load dynamics, the suspended load dynamics including load swing angles; designing an anti-swing controller, the anti-swing controller issuing the displacement commands to the helicopter attitude and position tracking controller, the displacement commands being based on time-delayed feedback of the load swing angles represented by the equations: where x s and y s are additional displacement added to the helicopter trajectory in a longitudinal and lateral direction, wherein φL is the load angle in a xz plane and θL is the load angle out of a xz plane, respectively, k is a feedback gain, L is a load cable length, and τ is a time delay introduced in the feedback of the load swing angles; optimally selecting values for the k, and τ parameters by minimizing a swing index function ISH expressed in terms of a time history integral from zero to tf of the load swing angles in the longitudinal φL, and lateral θL directions, the index function being represented by the equation: the index function minimizing being performed using an evolutionary computation algorithm, wherein said evolutionary computation algorithm is a particle swarm optimization algorithm; iteratively calculating a fitness value using the particles, wherein said fitness value is used to provide a global minimum of said index function; and implementing an optimized anti-swing controller in a feedback control loop with the tracking controller to achieve suspended load swing reduction of the suspended load and stability control of the helicopter.