Showing papers by "Rogelio Lozano published in 2008"

Triple tilting rotor mini-UAV: Modeling and embedded control of the attitude

Abstract: The goal of this paper is to present a novel configuration for a three-rotor mini unmanned aerial vehicle (UAV). The proposed design incorporates advantageous structural features which enhance the maneuverability of the rotorcraft. The detailed mathematical model of the vehicle's attitude is obtained through the Newton-Euler formulation. In terms of control, we propose a control law which is robust with respect to dynamical couplings and adverse torques. The vehicle tilts simultaneously the three rotors to stabilize the yaw dynamics. The resulting control algorithm is simple for embedded purposes. A customized low-cost embedded system was developed to test an autonomous stabilized-attitude flight, obtaining satisfactory results.

Controllability and observability of leader-based multi-agent systems

Abstract: In this work we analyze the controllability and observability properties of several interconnection configurations such as the chain topology and cyclic topology as well as combinations of these two topologies. A leader/follower control strategy is proposed to control the center of mass of the multiple agent system. It is shown that the trajectory tracking for a multi-agent system converges to the constant input reference given only to the leader. Also, it is shown that choosing an appropriated gain, the agents achieve consensus for constant input reference.

Real-time stabilization of a small three-rotor aircraft

Abstract: This paper describes the design and control algorithm of an original configuration for a small aerial vehicle having three rotors with fixed-pitch propellers. The mechanism of forces and moments generation is described and compared with other vertical take-off and landing (VTOL) vehicles. A mathematical model of the body-forces generation process as well as the 6-DOF (degree of freedom) krotorcraft dynamics is presented. A stabilization algorithm is proposed which takes into account the input amplitude bounds as well as nonlinear couplings in the three-rotor dynamics. The performance of the control strategy is shown in real-time experiments.

Spherical simplex sigma-point Kalman filters: A comparison in the inertial navigation of a terrestrial vehicle

Abstract: To determine the position of a mobile robot continues being a complex and interesting challenge in localization algorithms, whose solution requires the use of estimation techniques of nonlinear systems, a well selection of sensors that fulfill the restrictions imposed by the characteristics of the system, and the selection of the suitable algorithm of navigation. In this article, the performance of three variants of Sigma Point Kalman Filter (SPKF) are analyzed and compared, where the selection strategy of spherical simplex sigma points is used in order to improve its performance for real time execution. The analyzed filters are applied to an inertial navigation system that is used for the localization of a terrestrial mobile vehicle. The obtained results of the comparative analysis are illustrated by some simulations.

Simple Real-Time Stabilization of Vertical Takeoff and Landing Aircraft with Bounded Signals

Abstract: C ; _ = Coriolis matrix Ez = unitary vector in the z coordinate F 2 R = translational forces applied to the rotorcraft f = vector of the principal nonconservative forces applied to the object, including thrusts and drag terms associated with the rotors fi = force produced by motor i g = acceleration due to gravity I 2 R 3 = inertia matrix around the center of mass (expressed in the body fixed frame) J = inertia matrix for the full rotational kinetic energy of the helicopter expressed directly in terms of the generalized coordinates m = mass of the rigid object _ = generalized velocities in the region in which the Euler angles are valid q T = vector of the generalized coordinates of the aircraft R ; ; 2 SO 3 = rotational matrix Trot = rotational kinetic energy Ttrans = translational kinetic energy U = potential energy of the rigid object ui = control input i v = linear velocity expressed in the inertial frame ; ; T = orientation of the rotorcraft representing the Euler angles (yaw, pitch, and roll angles) x; y; z T = position of the center of mass of the aircraft relative to a fixed origin; x and y are coordinates in the horizontal plane, and z is the vertical position ; ; T = yawing, pitching, and rolling moments, respectively = angular velocity of the airframe expressed in the body fixed frame = skew-symmetric matrix of the vector ! = angular velocity vector expressed in the body fixed frame

Stability and robust stability of integral delay systems

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.

Strictly positive real systems based on reduced-order observers

Abstract: We study the extension of the class of linear time-invariant open-loop systems that may be transformed into SPR systems introducing a reduced-order observer. It is shown that for open-loop stable systems a cascaded observer achieves the result. For open-loop unstable systems observer-based feedback is required to succeed. In general, any stabilizable and observable system may be transformed into an SPR system defining a new output based on the observer state. This overcomes the old conditions of minimum phase and relative degree one for the case of keeping the original output. The result is illustrated with some examples.

Dynamic analysis of an enzymatic membrane reactor

Abstract: This paper is focused on the analysis of nonlinear dynamics of an enzymatic process involving three chemical species. The work is based on the immobilization of Acetyl-cholinesterase enzyme into an artificial proteinic membrane. Our objective is to study oscillations observed in the membrane potential difference during experimental works. Stability analysis is provided for the system from a theoretical point view. Reported results allow the analysis of the profile of diffusion motion of molecules inside the membrane.

Brief paper Synchronization of bilateral teleoperators with time delay I

Abstract: Bilateral teleoperators, designed within the passivity framework using concepts of scattering and two-port network theory, provide robust stability against constant delay in the network and velocity tracking, but cannot guarantee position tracking in general. In this paper we fundamentally extend the passivity-based architecture to guarantee state synchronization of master/slave robots in free motion independent of the constant delay and without using the scattering transformation. We propose a novel adaptive coordination architecture which uses state feedback to define a new passive output for the master and slave robots containing both position and velocity information. A passive coordination control is then developed which uses the new outputs to state synchronize the master and slave robots in free motion. The proposed algorithm also guarantees ultimate boundedness of the master/slave trajectories on contact with a passive environment. Experimental results are also presented to verify the efficacy of the proposed algorithms. c 2008 Elsevier Ltd. All rights reserved.