No abstract

No abstract

No abstract

No abstract

Unlike existing literature on obstacle avoidance of UAVs that mainly propose only guidance techniques (using either kinematic or, at best, point-mass models), an innovative partial integrated guidance and control (PIGC) technique is presented in this paper for reactive obstacle avoidance of UAVs that uses the Six-DOF flight dynamics of the vehicle directly. First, a collision cone approach is used to predict any possible collision with the obstacle and, if necessary, to compute an alternate aiming direction for the vehicle. The vehicle guidance strategy then attempts to quickly align the velocity vector of the vehicle along the aiming point within a fraction of the available time-to-go, which ensures quick reaction leading to safety of the vehicle. The PIGC algorithm presented here essentially has two loops in cascade. In the outer loop (i.e the guidance loop), the velocity vector is aligned with the aiming point by correcting the flight path angles, while simultaneously assuring turn coordination. The outer loop essentially generates the commanded body rates for the inner loop while enforcing the angle corrections through dynamic inversion. In the inner loop (i.e the control loop), these body rates are tracked in a fast dynamic inversion loop by generating the necessary control surface deflections. Simulation studies have been carried out with Six-DOF model of a small real fixed wing UAV with and without actuator model in the system. The comparative study clearly show that the proposed PIGC technique is quite effective in avoiding collisions for both single as well as multiple obstacles. Nomenclature SWing planform area, m 2 bWing span, m c Chord length, m dOffset of the thrust line from the CG of the vehicle., m mMass of the UAV, kḡ q Dynamic pressure, Pa g Acceleration due to gravity, m/s 2 V T