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Showing papers by "Rogelio Lozano published in 2010"


Journal ArticleDOI
TL;DR: In this article, a special class of integral delay systems arising in several stability problems of time-delay systems were considered and robust stability conditions in terms of Lyapunov-Krasovskii functionals were derived.
Abstract: In this paper we consider a special class of integral delay systems arising in several stability problems of time-delay systems. For these integral systems we derive stability and robust stability conditions in terms of Lyapunov–Krasovskii functionals. More explicitly, after providing the stability conditions we compute quadratic functionals and apply them to derive exponential estimates for solutions, and robust stability conditions for perturbed integral delay systems. Copyright © 2008 John Wiley & Sons, Ltd.

71 citations


Proceedings ArticleDOI
01 Dec 2010
TL;DR: A method to measure translational speed as well as the UAV 3D position in a local frame and the performance of three control techniques: Nested Saturations, Backstepping and Sliding Modes is presented.
Abstract: In this paper, we present a comparison of three control techniques: Nested Saturations, Backstepping and Sliding Modes. The control objective consists of obtaining the best control strategy to stabilize the position of a quad-rotor when using visual feedback. We propose a method to measure translational speed as well as the UAV 3D position in a local frame. The selected controllers were implemented and tested in real-time experiments. The obtained results demonstrate the performance of such methodologies applied to the quad-rotor system.

51 citations


Journal ArticleDOI
TL;DR: In this paper, the maximum parametric uncertainty is calculated when a multivariable PD controller is used to stabilize the attitude of the X4-flyer, which is based on the value set characterization approach of the mathematical model.

45 citations


Journal ArticleDOI
TL;DR: In this paper, a predictor-based controller for time-varying delay systems is presented and its robustness properties for different uncertainties are analyzed, and the experimental results show good performance and robustness of the proposed scheme even in the presence of long delay uncertainties.

43 citations


Proceedings ArticleDOI
03 May 2010
TL;DR: A nonlinear coordinated control design for multiple autonomous vehicle synchronization is developed that is based on a leader/follower structure of multiple robot systems.
Abstract: In this paper, the coordination and trajectory tracking control design of multiple mini rotorcraft systems are discussed. The dynamic model of a mini rotorcraft is presented using the Newton-Euler formalism. Our approach is based on a leader/follower structure of multiple robot systems. The centroid of the coordinated control subsystem is used for trajectory tracking purposes. A nonlinear coordinated control design for multiple autonomous vehicle synchronization is developed. The analytic results are supported by simulation tests.

31 citations


Journal ArticleDOI
TL;DR: 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 aateral force coupling, ϵ, as long as such a parameter takes small enough values.
Abstract: This work is devoted to prove that the nonlinear control scheme previously proposed by Zavala-Rio, 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.

20 citations


Proceedings ArticleDOI
29 Jul 2010
TL;DR: In this article, a Lyapunov-based optimal control design for coordination and trajectory tracking of multiple robot systems with parametric uncertainty is presented, which is extended to the case of time-delay multi-agent systems using the value set characterization.
Abstract: In this paper, the use of a robust optimal control as a tool to design a trajectory tracking control for multiple agent systems is discussed. Our approach is based on a leader/follower structure of the multiple robot systems. It is shown that for multiple agent system with cyclic and chain topology of information exchange the result is achieved. A Lyapunov based optimal control design for coordination and trajectory tracking of multiple agent systems with parametric uncertainty is presented. Subsequently, this result is extended to the case of time-delay multi-agent system using the value set characterization to verify the robust stability of the closed loop system. The results are illustrated with several examples and simulations.

13 citations


Journal ArticleDOI
TL;DR: Experimental autonomous flight was successfully achieved, which validates the sensing strategy as well as the embedded control law, and employed a saturated-based control to stabilize the state of the aircraft around the origin.
Abstract: In this paper we address the stabilization of the attitude and position of a birotor miniUAV to perform autonomous flight. For this purpose, we have implemented a Kalman-based sensor fusion between inertial sensors (gyros-accelerometers) and the optical flow (OF) provided by the vehicle. This fusion algorithm extracts the translational-OF (TOF) component and discriminates the rotational OF (ROF). The aircraft's position is obtained through an object detection algorithm (centroid tracking). Newton-Euler motion equations were used to deduce the mathematical model of the vehicle. In terms of control we have employed a saturated-based control to stabilize the state of the aircraft around the origin. Experimental autonomous flight was successfully achieved, which validates the sensing strategy as well as the embedded control law.

12 citations


Proceedings ArticleDOI
01 Oct 2010
TL;DR: The dynamic model of the mini rotorcraft is presented using the Newton-Euler formalism and a nonlinear controller based on nested saturations and a multi-agent consensus control are combined to obtain a flight formation control for a multiplemini rotorcraft system.
Abstract: This paper addresses the coordination and trajectory tracking control design for a multiple mini rotorcraft system. The dynamic model of the mini rotorcraft is presented using the Newton-Euler formalism. Our approach is based on a leader/follower structure of multiple robot systems. A nonlinear controller based on nested saturations and a multi-agent consensus control are combined to obtain a flight formation control for a multiple mini rotorcraft system. The centroid of the coordinated control subsystem is used for trajectory tracking purposes. The analytic results are supported by simulation tests.

7 citations


Journal ArticleDOI
TL;DR: A vision system that deals with the problem of local estimation of the position and velocity of a UAV quad-rotor indoor based in the estimation of homographies from a visual landmark is presented.

6 citations


Journal ArticleDOI
TL;DR: In this paper, the authors used the optical flow in combination with the integration of gyro measurement to estimate the linear and rotational yaw velocities as well as the position and velocity of a UAV.
Abstract: This paper addresses the hover flight stabilization problems of a four-rotor rotorcraft using fusion of visual information given by a single camera and inertial information obtained from an Inertial Measurement Unit. We use the optical flow in combination with the integration of gyro measurement to estimate the linear and rotational yaw velocities as well as the position and velocity of a UAV. Experimental results show a satisfactory flight performance of the four-rotor rotorcraft platform.

Journal ArticleDOI
TL;DR: In this article, a hybrid control algorithm based on saturation functions and its real-time application to a ground vehicle is presented, which is developed from a nonlinear continuous control law and the objective is to obtain the optimal sampling period to apply the controller in real experiences.

Proceedings Article
15 Dec 2010
TL;DR: A method to measure translational speed as well as UAV X-Y-Z position in a local frame and the performance of such methodologies applied to the quadrotor system is demonstrated.
Abstract: In this paper, we present a comparison of three control techniques: Nested Saturations, Backstepping and Sliding Modes. The control objective consists to stabilize the position of a quadrotor by using visual feedback. Our interest is to obtain the better control strategy when we use visual feedback. We propose a method to measure translational speed as well as UAV X-Y-Z position in a local frame. The selected controllers where implemented and tested in real-time experiments. The obtained results demonstrate the performance of such methodologies applied to the quadrotor system.

Journal ArticleDOI
TL;DR: In this article, the authors used the optical flow in combination with the integration of gyro measurement to estimate the linear and rotational yaw velocities as well as the position and velocity of a UAV.
Abstract: This paper addresses the hover flight stabilization problems of a four-rotor rotorcraft using fusion of visual information given by a single camera and inertial information obtained from an Inertial Measurement Unit. We use the optical flow in combination with the integration of gyro measurement to estimate the linear and rotational yaw velocities as well as the position and velocity of a UAV. Experimental results show a satisfactory flight performance of the four-rotor rotorcraft platform.