A constant guidance law-based collision avoidance for unmanned aerial vehicles

A method of automatic collision avoidance based on constant guidance law is proposed to solve the problem that the collision avoidance time is difficult to be estimated accurately during the collision avoidance process. The guidance command of the collision avoidance method is constant, and the lower bound of the constant guidance command satisfying the safe collision avoidance requirement is given by geometric method. Then, a collision avoidance time estimation method based on particle swarm optimization is proposed. In addition, the attitude control loop adopts the nonlinear proportional-integral-derivative based on tracking-differentiator, and the sufficient conditions for the system stability are given using the T-passive method. The simulation results show that the collision avoidance time estimation error is small and the maneuvering range of collision avoidance is smaller than the collision avoidance method based on proportional guidance and nonlinear dynamic inverse guidance. This method can achieve collision avoidance under the influence of wind disturbance and safety distance abrupt change.