Daniela Juanita López-Araujo

Global stabilisation of the PVTOL aircraft with lateral force coupling and bounded inputs

This work is devoted to prove that the nonlinear control scheme previously proposed by Zavala-Río, Fantoni and Lozano for the global stabilisation of the planar vertical take-off and landing (PVTOL) aircraft with bounded inputs neglecting the lateral force coupling is robust with respect to the parameter characterising such a lateral force coupling, ϵ, as long as such a parameter takes small enough values. In other words, global stabilisation is achieved even if ϵ > 0, provided that such a parameter be sufficiently small. As far as the authors are aware, such a property has not been proved in other existing control schemes when the value of ϵ is not known. The presented methodology is based on the use of embedded saturation functions. Furthermore, experimental results of the control algorithm implemented on a real prototype are presented.

Global Adaptive Regulation of Robot Manipulators With Bounded Inputs

Abstract In this work, an SP-SD-type control scheme with adaptive gravity compensation for the global regulation of robot manipulators with bounded inputs is proposed. As far as the authors are aware, the developed adaptive controller is the first one that guarantees the regulation objective: globally, avoiding discontinuities in the control expression as well as in the adaptation auxiliary dynamics, avoiding input saturation, and imposing no saturation-avoidance restriction on the choice of the control gains. Experimental results show the efficiency of the proposed adaptive scheme.

Closed-loop identification and tracking control of Lagrangian systems under input constraints

In this paper global tracking and parameter convergence are proven for an adaptive control algorithm with independently saturated proportional and derivative terms through a persistency of excitation condition, while guaranteeing the inputs to never reach their natural saturation limit. As far as the authors are aware this is the first work that achieves globally the motion control objective and system identification, avoiding actuator saturation.

Observer-less output-feedback global continuous control for the finite-time and exponential stabilization of mechanical systems with constrained inputs

Abstract An observer-less output-feedback global continuous control scheme for the finite-time or (local) exponential stabilization of mechanical systems with constrained inputs is proposed. The approach is formally developed within the theoretical framework of local homogeneity. The closed-loop analysis incorporates a complementary insight on the control-induced motion dissipation through an ad hoc feedback-system passivity theorem. The work includes a simulation implementation section where the performance difference of the proposed scheme with previous observer-based and differentiation algorithms is brought to the fore.

Further advancements on the output-feedback global continuous control for the finite-time and exponential stabilisation of bounded-input mechanical systems: desired conservative-force compensation and experiments

ABSTRACT Global Saturating-Proportional Saturating-Derivative (SP-SD) type continuous control for the finite-time or (local) exponential stabilisation of mechanical systems with bounded inputs is achieved avoiding velocity variables in the feedback, and further simplified through desired conservative-force compensation. The proposed output-feedback controller is not a simple extension of the on-line compensation case but it rather proves to entail a closed-loop analysis with considerably higher degree of complexity that gives rise to more involved requirements. Interestingly, the proposal even shows that actuators with higher power-supply capabilities than in the on-line compensation case are required. Other important analytical limitations are further overcome through the developed algorithm. Experimental tests on a multi-degree-of-freedom robot corroborate the efficiency of the proposed approach.

Output-Feedback Adaptive SP-SD-Type Control with an Extended Continuous Adaptation Algorithm for the Global Regulation of Robot Manipulators with Bounded Inputs

In this work, an output-feedback adaptive SP-SD-type control scheme for the global position stabilization of robot manipulators with bounded inputs is proposed. Compared with the output-feedback adaptive approaches previously developed in a bounded-input context, the proposed velocity-free feedback controller guarantees the adaptive regulation objective globally (i.e. for any initial condition), avoiding discontinuities throughout the scheme, preventing the inputs from reaching their natural saturation bounds and imposing no saturation-avoidance restrictions on the choice of the P and D control gains. Moreover, through its extended structure, the adaptation algorithm may be configured to evolve either in parallel (independently) or interconnected to the velocity estimation (motion dissipation) auxiliary dynamics, giving an additional degree of design flexibility. Furthermore, the proposed scheme is not restricted to the use of a specific saturation function to achieve the required boundedness, but may involve any one within a set of smooth and non-smooth (Lipschitz-continuous) bounded passive functions that include the hyperbolic tangent and the conventional saturation as particular cases. Experimental results on a 3-degree-of-freedom manipulator corroborate the efficiency of the proposed scheme.