Hybrid systems with memory are dynamical systems exhibiting both hybrid and delay phenomena. We present a general modelling framework for such systems using hybrid functional inclusions, whose generalized solutions ar...
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We show that the robustification method of Krstic et al. (1996) for nonlinear systems with linear input unmodeled dynamics guarantees global boundedness of closed loop solutions when the unmodeled dynamics subsystem i...
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We show that the robustification method of Krstic et al. (1996) for nonlinear systems with linear input unmodeled dynamics guarantees global boundedness of closed loop solutions when the unmodeled dynamics subsystem is relative degree zero and minimum phase. We also prove that the solutions can be made to converge to an arbitrarily small ball around the origin.
Analyzes the robustness of a nonlinear observer design introduced previously by the authors. For uncertainties in the nonlinearities, bounds are given within which the observer error gradually increases with an increa...
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ISBN:
(纸本)0780366387
Analyzes the robustness of a nonlinear observer design introduced previously by the authors. For uncertainties in the nonlinearities, bounds are given within which the observer error gradually increases with an increase in the uncertainty. For dynamic modeling errors, a robust output-feedback design is developed using ISS small-gain tools. A jet engine compressor example is used to illustrate the design.
We consider the problem of steering an autonomous vehicle to locate a radiation source utilizing measurements of the radiation intensity only. We propose a control algorithm that locates the source through a sequence ...
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We consider the problem of steering an autonomous vehicle to locate a radiation source utilizing measurements of the radiation intensity only. We propose a control algorithm that locates the source through a sequence of line minimizations of the radiation intensity. We implement in a hybrid controller, with sample-and-hold and logic variables, a discretized version of the algorithm suitable for steering a point-mass vehicle. The algorithm confers global convergence and practical stability properties to the closed-loop hybrid system. We discuss these properties and characterize the region of convergence for the vehicle. Convergence and stability results are supplemented with simulations.
Auto-regulatory transcriptional feedback, where the protein expressed from a gene inhibits its own transcription, is known to reduce stochastic fluctuations in protein numbers. Recent work has demonstrated the existen...
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ISBN:
(纸本)9781424445233
Auto-regulatory transcriptional feedback, where the protein expressed from a gene inhibits its own transcription, is known to reduce stochastic fluctuations in protein numbers. Recent work has demonstrated the existence of negative feedback loops not only at the transcriptional level but also at the translational level. We investigate the noise suppression abilities of feedback loops at the translational level and compare them with transcriptional feedback. In particular, we consider two feedbacks at the translational level: translation blocking feedback, where the protein inhibits the translation of its mRNA, and degradation enhancing feedback, where the protein increases the degradation rate of its mRNA. We derive analytical formulas for the protein noise level corresponding to different feedback mechanisms. These noise levels are then compared with each other for fixed steady-state average number of protein and mRNA molecules. We show that translation blocking feedback always yields smaller levels of protein noise than transcriptional feedback. We further show that the difference between the protein noise levels with translation blocking and transcriptional feedback critically depends on how fast the protein dynamics is compared to the mRNA dynamics. In particular, this difference increases as we make the protein dynamics faster than the mRNA dynamics, while making it slower has an opposite effect. Finally, we show that degradation enhancing feedback provides the same noise level as transcriptional feedback. This result shows that regulation at the translational level may not always be better than regulation at the transcriptional level in terms of reducing noise in the protein population.
We consider nonlinear systems in feedforward form and redesign nested saturation control laws to guarantee global asymptotic stability in the presence of unmodeled dynamics appearing at the system input. Unlike most p...
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We consider nonlinear systems in feedforward form and redesign nested saturation control laws to guarantee global asymptotic stability in the presence of unmodeled dynamics appearing at the system input. Unlike most previous results, this redesign is applicable to a large class of unmodeled dynamics, including actuators that change the relative degree of the system.
We address the windup problem arising from actuator rate and magnitude limits in the context of manual flight control for an open loop unstable aircraft. We present a new anti-windup solution tailored for this problem...
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We address the windup problem arising from actuator rate and magnitude limits in the context of manual flight control for an open loop unstable aircraft. We present a new anti-windup solution tailored for this problem and we compare our result with an optimal solution.
One DOF (degree of freedom) Twin Rotor multi-input multi-output system (TRMS) is one of the benchmarked dynamical systems which has striking comparability with Helicopter. Design of controllers for such complex air ve...
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We apply recent results on robust global asymptotic stabilization of the attitude of a single rigid body to the problem of synchronizing the attitude of a network of rigid bodies using graph-local information. The pro...
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This paper links the Bode integral characterization of performance limitations in linear control systems with the limiting cost of a particular linear cheap control. This link allows us to establish analogous feedback...
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ISBN:
(纸本)0780341872
This paper links the Bode integral characterization of performance limitations in linear control systems with the limiting cost of a particular linear cheap control. This link allows us to establish analogous feedback limitations in nonlinear systems. We show how unstable zero dynamics impose unavoidable obstructions to the closed-loop performance.
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