Guillermo Obregon-Pulido

A globally convergent estimator for n-frequencies

In this paper, we propose a solution to the well-known problem of ensuring a simultaneous globally convergent online estimation of the state and the frequencies of a sinusoidal signal composed of n sinusoidal terms. We present an estimator which guarantees global boundedness and convergence of both the state estimation and the frequency estimation for all initial conditions and frequency values.

A Structurally Stable Globally Adaptive Internal Model Regulator for MIMO Linear Systems

The problem of compensating an uncertain disturbance and/or tracking some reference signals for a general linear MIMO system is studied in this work using the robust regulation theory frame. The disturbances are assumed to be composed by a known number of distinct sinusoidal signals with unknown phases, amplitude and frequencies. Under suitable assumptions, an exponentially convergent estimator of the unknown disturbance parameters is proposed and introduced into the classical robust regulator design to obtain an adaptive controller. This controller guarantees that the closed-loop robust regulation is attained in some neighborhood of the nominal values of the parameters of system. A simulated example shows the validity of the proposed approach.

A Globally Adaptive Internal Model Regulator for MIMO Linear Systems.

The problem of compensating noise and/or track some reference signal with n unknown frequencies in general linear MIMO systems is treated in this work. We derive a frequency estimator that ensures closed loop robust regulation in some neighborhood of the nominal values of the system as well.

Bilateral Teleoperation Control Without Velocity Measurements

Abstract This paper presents two controllers for a nonlinear bilateral teleoperation system that do not rely on velocity measurements. Under the reasonable assumptions that the human operator and the environment define passive maps from force to velocity, both controllers can ensure boundedness of velocities and position error. Moreover, if the human and environment forces are bounded, one of the controllers ensure velocity synchronization and the other velocity convergence to zero. Simulations, comparing the performance on free motion and interacting with a stiff wall, support the performance of the reported schemes.

Adaptive internal model regulation of a pvtol vehicle

Abstract We propose an adaptive control scheme to regulate the landing process of a PVTOL vehicle on an oscillating platform. In this approach we consider the oscillating reference as a sum of sinusoidal signals whose frequencies, phase and amplitude are all unknown. The suggested controller does not use velocity measurements and guarantee that the equilibrium point of the closed loop system is locally exponentially stable.

On the equivalence of z-domain and s-domain: The inverse of convolution integral and its application to systems identification

In this work we present an equation that obtains the Laplace transform of a time function from its z-transform. This equation is the integral representation of the inversion of the well know convolution integral, which obtains the z-transform using the Laplace transform. The paper also presents the application of the presented method to obtain the estimation of continuous systems through their discrete time samples.

Output regulation of linear multi-agent systems through a leader

In this paper, the output regulation problem of linear multi-agent systems through one leader is considered. The overall system consists of a leader agent, which can access the exogenous signal, and the followers agents. The method considers a static feedback control law of the output agents and a robust control applied to the leader agent, allowing synchronization of the agents in the system. Finally, a numerical example illustrates the efficacy of the presented results.

On contraction analysis of synchronization of neuron networks

The synchronization of neuron networks using the contraction theory is reported in this contribution. The contraction theory provides a simple method to determine convergence of trajectories of the systems in the network instead of the Master Stability Function and the calculation of Lyapunov exponents. The objective is to determine the contraction region where once the trajectories reach such region they will converge each other and remain in such a contraction region. Such a condition lies mainly on the system parameters, network topology and coupling strength.

An adaptive control to perform tracking in DC to DC power converters

In this paper we design a controller that solves the tracking problem for the boost and buck-boost converters. A stable nonlinear system is obtained that produces the necessary inputs in order to exactly track the inductor current reference. This property is used to track a given reference signal for the capacitor voltage. We also present an study of the bounds that must be satisfied by the current reference in order to track the voltage reference ƒ(τ) = A+B sin(wτ) in an approximate way.

Mutual Synchronization of Nonidentical Open Kinematic Chains

In this contribution we present the mutual synchronizationof an ensemble of robots with strictly differentarchitecture. The main idea is to achieve synchronizationin an group of robots composed by rotational-rotationaland rotational-prismatic architecture. The synchronization isachieved into the workspace, this is, the end position ofeach robot is equal to the rest of the robots. It impliesthat the resulting workspace is composed by the intersectionof the corresponding workspace. The mutual synchronizationis achieved by means of a PID controller and numericalsimulations are provided to illustrate the results.