In this paper, we present a controller design and its implementation on a mini rotorcraft having four rotors. The dynamic model of the four-rotor rotorcraft is obtained via a Lagrange approach. The proposed controller is based on Lyapunov analysis using a nested saturation algorithm. The global stability analysis of the closed-loop system is presented. Real-time experiments show that the controller is able to perform autonomously the tasks of taking off, hovering, and landing.

The design of robust tracking control for Quad-Rotors is an important and challenging problem nowadays. In this paper a robust tracking output-control strategy is proposed for a Quad-Rotor under the influence of external disturbances and uncertainties. Such a strategy is composed of a Finite-Time Sliding-Mode Observer (FTSMO) which estimates the full state from the measurable output and identifies some type of disturbances; and also of a combination between PID controllers and Continuous Sliding-Modes Controllers (Continuous-SMCs), that robustly track a desired time-varying trajectory with exponential convergence and despite the influence of external disturbances and uncertainties. The closed-loop stability is provided based on Input-to-State Stability (ISS) and Finite- Time ISS (FT-ISS) properties. Finally, experimental results in real-time show the performance of the proposed control strategy.

A novel proportional-integral-derivative (PID)-type motion controller for a quadrotor is introduced in this paper. A rigorous analysis of the closed-loop system trajectories is provided, and gain tuning guidelines are discussed. Real-time experimental results consisting of the implementation of a PID-based scheme, a sliding-mode controller, and the new scheme are given. Gains are selected so that the three tested controllers present the same energy consumption. In order to assess the robustness of the controllers tested, experiments are carried out in the presence of disturbances in one of the actuators. Specifically, the disturbance consists in attenuating the force delivered. Better tracking accuracy is obtained with the introduced nonlinear PID-type algorithm.