In this work, the problem of navigation control of a quad-rotor, which includes path planning (to a desired trajectory with obstacle avoidance) and tracking control, is addressed. Path planning is achieved by means of the velocity field technique, since this method generates smooth trajectories that are suitable for this kind of vehicles. We propose a recursive method for the composition of the total velocity reference. In order to achieve a good tracking of the generated references, a saturated controller is used, namely, nested saturation. It is demonstrated that the velocity reference can be tracked with a reduction in the order of the controller, from four to three saturators, which simplifies the implementation. Numerical results show that a correct tracking could be guaranteed.
Geometric path planning and tracking control with bounded steering angle for the parking problem of automatic vehicles