Papers by José-Job Flores-Godoy
International Journal of Advanced Robotic Systems, 2015
This paper presents a two-level control strategy for the trajectory tracking of the quadcopter. T... more This paper presents a two-level control strategy for the trajectory tracking of the quadcopter. The external loop is designed to move the translational dynamics of the robot to follow smooth parametric functions using an appropriate variables substitution. The outer loop generates the desired trajectories of the orientation angles, which are controlled in the inner loop. The parameter gains are calculated using linear optimal control in order to minimize the energy consumption of the rotors. The control architecture is designed to be compatible with standard electronic platforms of commercial quadcopters and incorporates the purpose of maximizing flight time, an important requirement in real applications of multi-rotor aerial vehicles. Some numerical simulations show the performance of the control approach.
We present in this paper some results concerning the preservation of control-oriented properties ... more We present in this paper some results concerning the preservation of control-oriented properties in Linear Time-Invariant systems (LTI systems) when applying substitutions of the Laplace variable s by a particular class of positive real functions, the socalled Positive Real functions of zero relative degree (PR0 functions). In particular, we show that the families of Bounded Real (BR), Strictly Bounded Real (SBR), and Positive Real (PR), rational functions are closed under compositions with the specified class of positive real functions. We also give some results concerning the preservation of stability in proper real rational transfer functions (in fact this is our main result), as well as the preservation of the H ∞norm bound for this class of systems. Our study is restricted to Single-Input Single Output (SISO) systems.
WSEAS Transactions on Circuits and Systems
In this work, using algebraic methods, we characterize the parameters of a linear fractional tran... more In this work, using algebraic methods, we characterize the parameters of a linear fractional transformation such that the composition of a class of rational function with the linear fractional transformation preserves stability, in the case that the rational function is stable, or stabilizes the original rational function, in the case that the rational function is unstable. As a consequence, we obtain a dual result about the robust stabilization of a plant-represented as a rational function-compensated with a controller when there is a nonlinear disturbance induce by function composition on the parameters of the controller. This implies the non-fragility of the controller and also the plant robust stabilization for the same class of disturbances. Also, for a particular choice of one of the parameters in the linear fractional transformation, the composition of functions preserves the structure of Proportional, Proportional-Derivative and Proportional-Derivative-Integral type of controllers. Finally, results about stabilization based in passivity using the linear fractional transformation are given.
In this work, using algebraic methods, we characterize the parameters of a linear fractional tran... more In this work, using algebraic methods, we characterize the parameters of a linear fractional transformation such that the composition of a class of rational function with the linear fractional transformation preserves stability, in the case that the rational function is stable, or stabilizes the original rational function, in the case that the rational function is unstable. As a consequence, we obtain a dual result about the robust stabilization of a plant-represented as a rational function-compensated with a controller when there is a nonlinear disturbance induce by function composition on the parameters of the controller. This implies the non-fragility of the controller and also the plant robust stabilization for the same class of disturbances. Also, for a particular choice of one of the parameters in the linear fractional transformation, the composition of functions preserves the structure of Proportional, Proportional-Derivative and Proportional-Derivative-Integral type of controllers.
We present new methods for generating strong stability preserving maps (SSPMs). A first method is... more We present new methods for generating strong stability preserving maps (SSPMs). A first method is based on substitutions of strictly positive real functions with zero relative degree (SPR0 functions) in a Hurwitz polynomial, which consequently generates the family of the concerned operators. For our second method, based on sufficient conditions for the closeness of SPR0 functions by the Hadamard product of a class of polynomials with the numerator and denominator of the SPR0 function, can be interpreted as a vector-matrix product. With the introduction of a non-negative multiplier sequence, we show how the product between the non-negative multiplier sequence and a Hurwitz polynomial can be represented as a SSPM. It is also presented a relationship between stable polynomials and stable polynomials of the Jacobi class by the use of a multiplier sequence of the decreasing kind. In the last section, using generalized products of polynomials, stability and SPR0 functions are preserved by...
In this paper we present the change in the effective potential profile of some compounds when the... more In this paper we present the change in the effective potential profile of some compounds when the bandmixing of light and heavy holes is altered. We obtained this by applying Generalized Shur's Theorem to an eigenvalue quadratic problem obtained from a system with N second order coupled equations in the context of multiband effective mass approximation. We considered incident energy values that were lower, equal, and higher than the height of the dispersive potential barrier for different III-V semiconductor binary compounds. Most of the standard properties of the binary compounds in this study were guaranteed; but not all of the materials we chose, have shown the evolution we expected in their effective potential profile: some of the ones that constitute quantum wells (QW) in technological applications only evolve into effective barrier (B) behaviors for light holes (lh) when they are in different incident energy (E) ranges and present different bandmixing. None of the barrier ...
Several new features in the metamorphosis of the standardized fixed-height eff profile for holes,... more Several new features in the metamorphosis of the standardized fixed-height eff profile for holes, in the presence of gradually increasing valence-band mixing and biaxial pseudomorphic strain, are presented. In some − unstrained semiconducting layered heterostructures a fixed-height potential, is not longer valid for lh. Indeed, we found -as predicted for electrons, permutations of the eff character for lh, that resemble a "keyboard", together with band offset changes, whenever the valence-band mixing varies from low to large intensity. Meanwhile for strained heterostructures, the former behavior, had been also detected for hh. Strain is able to diminish the keyboard effect on eff , and also makes it emerge or vanish occasionally. We found that multiband-mixing effects and stress induced events, are competitors mechanisms that can not be universally neglected by assuming a fixed-height rectangular spatial distribution for fixedcharacter potential energy, as a reliable test-run input for heterostructures.
WSEAS Transactions on Circuits and Systems
In this paper, we use, extend and apply some classic results of the theory of dynamical systems t... more In this paper, we use, extend and apply some classic results of the theory of dynamical systems to study the preservation of synchronization in chaotical dynamical systems via Lyapunov method. The obtained results show that synchronization can be preserved after a particular class of changes are made to the linear part of the dynamical system. For illustrative purposes we apply a compound control law to achieve synchronization in a master-slave system. We also show that it is possible to preserve partial synchronization when an additive perturbation is included in the control law. We present numerical simulations to show the effectiveness of our method.
A model is presented, consisting of a single structureless particle on the line subject to a pote... more A model is presented, consisting of a single structureless particle on the line subject to a potential with three minima, with an exactly soluble ground level. In this model the ground level probability density becomes more sensitive to the global shape of the potential as the distance between the minima increases, so that for big enough distances small variations in the potential bring a qualitative change in the probability density, taking it from a unimodal, localized, distribution, to a bimodal one. We conjecture that this effect, of which we have not found any precedent in the literature, may be relevant in the design and characterization. of mesoscopic devices such as triple quantum well systems.
The evolution of transverse-momentum-dependent effective band offset (V eff ) profile for heavy (... more The evolution of transverse-momentum-dependent effective band offset (V eff ) profile for heavy (hh)-and light-holes (lh), is detailed studied. Several new features in the metamorphosis of the standardized fixed-height V eff profile for holes, in the presence of gradually increasing valence-band mixing and pseudomorphic strain, are presented. In some III − V unstrained semiconducting layered heterostructures a fixed-height potential, is not longer valid for lh. Indeed, we found -as predicted for electrons-, permutations of the V eff character for lh, that resemble a "keyboard ", together with bandgap changes, whenever the valence-band mixing varies from low to large intensity. Strain is able to diminish the keyboard effect on V eff , and also makes it emerge or vanish occasionally. We found that multiband-mixing effects and stress induced events, are competitors mechanisms that can not be universally neglected by assuming a fixed-height rectangular spatial distribution for fixed-character potential energy, as a reliable test-run input for heterostructures. Prior to the present report, neither direct transport-domain measurements, nor theoretical calculations addressed to these V eff evolutions and permutations, has been reported for holes, as far as we know. Our results may be of relevance for promising heterostructure's design guided by valence-band structure modeling to enhance the hole mobility in III − V materials.
Based on a wider systematic search on a family of 3-dimensional systems with quadratic nonlineari... more Based on a wider systematic search on a family of 3-dimensional systems with quadratic nonlinearities, three new simple chaotic systems were found. One of them has the unusual feature of having a stable equilibrium point, and it is the simplest one of other chaotic flows with this property. The others have some interesting special properties.
The first objective of the present work is to construct a simple reduced order model for BWR stab... more The first objective of the present work is to construct a simple reduced order model for BWR stability analysis, combining a two nodes nodal model of the thermal hydraulics with a two modes modal model of the neutronics. Two coupled non-linear integral-differential equations are obtained, in terms of one global (in phase) and one local (out of phase) power amplitude, with direct and cross feedback reactivities given as functions of thermal hydraulics core variables (void fractions and temperatures). The second objective is to apply the effective life time approximation to further simplify the nonlinear equations. Linear approximations for the equations of the amplitudes of the global and regional modes are derived. The linearized equation for the amplitude of the global mode corresponds to a decoupled and damped harmonic oscillator. An analytical closed form formula for the damping coefficient, as a function of the parameters space of the BWR, is obtained. The coefficient changes its sign (with the corresponding modification in the decay ratio) when a stability boundary is crossed. This produces a supercritical Hopf bifurcation, with the steady state power of the reactor as the bifurcation parameter. However, the linearized equation for the amplitude of the regional mode corresponds always to an over-damped and always coupled (with the amplitude of the global mode) harmonic oscillator, for every set of possible values of core parameters (including the steady state power of the reactor) in the framework of the present mathematical model. The equation for the above mentioned over damped linear oscillator is closely connected with a non-normal operator. Due to this connection, there could be a significant transient growth of some solutions of the linear equation. This behavior allows a significant shrinking of the basin of attraction of the equilibrium state. The third objective is to apply the above approach to partially study the stability of the regional mode and some results that could be of some interest in relation with stability studies made with both, more complex and realistic reduced order models.
The Open Cybernetics & Systemics Journal, 2011
This note gives results about the preservation of some dissipative properties of systems under a ... more This note gives results about the preservation of some dissipative properties of systems under a change of variables. In the textbooks it is not mentioned explicitly the relationship between the equations associated with the dynamics of a system and the selected Lyapunov function to establish its stability property, when a change of coordinates is used. Based on the fact that Lyapunov stability is preserved under these changes of variables, it is shown that various forms of dissipativity can be preserved. In addition, we will show that the input-state stability (ISS), integral input-to-state stability (iISS) and input/output to state stability (IOSS) can be preserved under this class of transformation. Some examples are given to show these results.
IECON '98. Proceedings of the 24th Annual Conference of the IEEE Industrial Electronics Society (Cat. No.98CH36200), 1998
This Multiscale Integration of Manufacturing and Assembly Processes (MIMAP) demonstration project... more This Multiscale Integration of Manufacturing and Assembly Processes (MIMAP) demonstration project investigates the integration of two or more Thrust Area Groups (TAGs) by creating a flow of information and processes from two areas of research. The control theory research of two different controllers for diffusion furnaces used in semiconductor manufacturing which predict a specific window of machine failure, the mean-time-before-failure
2008 5th International Conference on Electrical Engineering, Computing Science and Automatic Control, 2008
Classic results of the dynamical systems theory are extended and used to study the preservation o... more Classic results of the dynamical systems theory are extended and used to study the preservation of synchronization in chaotical dynamical systems. This results show that synchronization can be preserved after changes are made to the linear part of the dynamical system. When the jacobian matrix of the system is evaluated in the hyperbolic points, the structure of the signs of the eigenvalues of this matrix determine if the system is stable or unstable. In this work, we establish the sufficient conditions to preserve the structure of this hyperbolic points. Also, control tools are used to achieve synchronization in dynamical systems. Numerical simulations to very the effectiveness of the method are presented.
Physics Letters A, 2014
Shallow one-dimensional double well potentials appear in atomic and molecular physics and other f... more Shallow one-dimensional double well potentials appear in atomic and molecular physics and other fields. Unlike the "deep" wells of macroscopic quantum coherent systems, shallow double wells need not present low-lying two-level systems. We argue that this feature, the absence of a lowlying two-level system in certain shallow double wells, may allow the finding of new test grounds for quantum mechanics in mesoscopic systems. We illustrate the above ideas with a family of shallow double wells obtained from Bargman potentials through the Darboux-Bäcklund transform.
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Papers by José-Job Flores-Godoy