Robust distributed attitude synchronization of multiple three-DOF experimental helicopters

A novel control scheme for the regulation and trajectory tracking in spite of external perturbations of the three degrees of freedom (3-DOF) helicopter is presented. The scheme allows reduced control effort, vibration reduction, and accurate tracking. The proposed approach combines a continuous differentiator with an adaptive super twisting controller. The differentiator provides state estimation, whereas the adaptive super twisting algorithm is chosen such that the gains of the controller are adapted to reduce the control effort and do not require the knowledge of the bounds of the uncertainties and perturbations. Furthermore, finite time convergence of the continuous differentiator to a neighborhood of the desired trajectory, allows to design independently controller and the differentiator, satisfying the principle of separation. Finally, the proposed control scheme is validated by experimental tests under external disturbances.

Continuous Differentiator Based on Adaptive Second-Order Sliding-Mode Control for a 3-DOF Helicopter

This paper presents an adaptive neural network backstepping control design for an experimental helicopter with three rotational degrees of freedom. The helicopter system is described by a state-space model with unmodeled dynamics and external disturbances. By resorting to radial basis function neural networks with online gradient descent training, such unmodeled dynamics and external disturbances can be compensated in real time. With the help of Lyapunov stability criteria, it is proved that the desired trajectories can be boundedly tracked by the corresponding attitude angles of the helicopter under the proposed adaptive neural network backstepping controller. Compared with robust adaptive integral backstepping technique, our approach has smaller root mean squared error. Finally, four sets of contrastive experiment results are, respectively, given to show the effectiveness and advantages of the proposed control scheme.

Adaptive NN Backstepping Control Design for a 3-DOF Helicopter: Theory and Experiments

This paper proposes a robust attitude tracking controller for a table-mounted experimental helicopter that has three rotational degrees-of-freedom and only equips angular position sensors. The proposed controller can achieve output-feedback attitude tracking of the pitch and elevation channels of the helicopter. The experimental platform is subjected to model uncertainties, coupling effects, and equips with an independent active disturbance system, which have effectively examined the robustness of proposed controller. The control law includes a second-order auxiliary system to generate filtered error signals, and a discontinuous uncertainty and disturbance estimation (UDE) term to compensate the model uncertainties and external disturbances. A Lyapunov-based stability analysis shows the semiglobal asymptotic tracking ability of the proposed controller. The experimental results further demonstrate that the proposed method can achieve equivalent dynamic and static performance compared to other high-performance state-feedback methods, and even when the initial position is away from design point, it also gives more consistent responses than other linear methods.

Nonlinear Robust Attitude Tracking Control of a Table-Mount Experimental Helicopter Using Output Feedback

This paper deals with the robust position control problem for a three degree-of-freedom (3DOF) laboratory helicopter. The 3DOF helicopter system is a nonlinear multiple-input multiple-output (MIMO) uncertain system, and has the elevation, pitch, and travel angles. The proposed robust controller is a hierarchical controller including an attitude controller and a position controller. The position controller generates the desired reference of the pitch angle based on the tracking error of the travel angle, while the attitude controller achieves the reference tracking of the pitch and elevation angles. It is proven that the tracking errors of the three angles can converge into the given neighborhoods ultimately. Experimental results on the laboratory helicopter demonstrate the effectiveness of the proposed hierarchical control strategy.

Robust hierarchical control of a laboratory helicopter

This paper tackles the problem of robust output regulation for a 3-DOF helicopter. The considered system is subjected to model uncertainties and external perturbations. A sliding mode observer is used to estimate the state vector in finite time and identify the uncertainties and perturbations using the information of the equivalent output injection. Based on these estimations a robust regulation controller is designed. Experimental results show the feasibility of this approach.

A. Ferreira de Loza

Papers

Robust regulation for a 3-DOF helicopter via sliding-mode observation and identification