Lisa Fiorentini
Center for Automotive Research
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Publication
Featured researches published by Lisa Fiorentini.
Journal of Guidance Control and Dynamics | 2009
Lisa Fiorentini; Andrea Serrani; Michael A. Bolender; David B. Doman
This paper describes the design of a nonlinear robust adaptive controller for a flexible air-breathing hypersonic vehicle model. Because of the complexity of a first-principle model of the vehicle dynamics, a control-oriented model is adopted for design and stability analysis. This simplified model retains the dominant features of the higher-fidelity model, including the nonminimum phase behavior of the flight-path angle dynamics, the flexibility effects, and the strong coupling between the engine and flight dynamics. A combination of nonlinear sequential loop closure and adaptive dynamic inversion is adopted for the design of a dynamic state-feedback controller that provides stable tracking of the velocity and altitude reference trajectories and imposes a desired set point for the angle of attack. A complete characterization of the internal dynamics of the model is derived for a Lyapunov-based stability analysis of the closed-loop system, which includes the structural dynamics. The proposed methodology addresses the issue of stability robustness with respect to both parametric model uncertainty, which naturally arises when adopting reduced-complexity models for control design, and dynamic perturbations due to the flexible dynamics. Simulation results from the full nonlinear model show the effectiveness of the controller.
Automatica | 2012
Lisa Fiorentini; Andrea Serrani
The design of a nonlinear robust controller for a non-minimum phase model of an air-breathing hypersonic vehicle is presented in this work. When flight-path angle is selected as a regulated output and the elevator is the only control surface available for the pitch dynamics, longitudinal models of the rigid-body dynamics of air-breathing hypersonic vehicles exhibit unstable zero-dynamics that prevent the applicability of standard inversion methods for control design. The approach proposed in this paper uses a combination of small-gain arguments and adaptive control techniques for the design of a state-feedback controller that achieves asymptotic tracking of a family of velocity and flight-path angle reference trajectories belonging to a given class of vehicle maneuvers, in spite of model uncertainties. The method reposes upon a suitable redefinition of the internal dynamics of a control-oriented model of the vehicle dynamics, and uses a time-scale separation between the controlled variables to manage the peaking phenomenon occurring in the system. Simulation results on a full nonlinear vehicle model that includes structural flexibility illustrate the effectiveness of the methodology.
american control conference | 2008
Lisa Fiorentini; Andrea Serrani; Michael A. Bolender; David B. Doman
This paper describes the design of a nonlinear robust/adaptive controller for an air-breathing hypersonic vehicle model. Due to its complexity, a high fidelity model of the vehicle dynamics derived from first principles is used only in simulations, while a simplified model is adopted for control design. This control-oriented model retains most of the features of the high fidelity model, including non-minimum phase characteristic of the flight-path angle dynamics and strong couplings between the engine and flight dynamics, whereas flexibility effects are regarded as a dynamic perturbation. A nonlinear sequential loop-closure approach is adopted to design a dynamic state-feedback controller that provides stable tracking of velocity and altitude reference trajectories and allows to impose a desired trim value for the angle of attack. Simulation results show that the proposed methodology achieves excellent tracking performances in spite of parameter uncertainties.
AIAA Guidance, Navigation and Control Conference and Exhibit | 2007
Lisa Fiorentini; Andrea Serrani; Michael A. Bolender; David B. Doman
Abstract : This paper describes the design of a nonlinear controller for an air-breathing hypersonic vehicle. To overcome the analytical intractability of this model, a nominal control-oriented model is used to derive the control law. The nominal model has unstable zero dynamics with respect to the output to be controlled, namely flight path angle and velocity, and presents intricate couplings between the engine dynamics and flight dynamics. The flexible effects have not been included in the analysis yet. Adaptive control techniques and robust control techniques are applied to achieve tracking of velocity and altitude trajectories. Simulation results are provided to show that the derived control law allows to achieves excellent tracking performance on the nominal model.
american control conference | 2009
Lisa Fiorentini; Andrea Serrani; Michael A. Bolender; David B. Doman
Longitudinal rigid-body models of air-breathing hypersonic vehicle dynamics are characterized by exponentially unstable zero-dynamics when longitudinal velocity and flight-path angle (FPA) are selected as regulated output. To enable application of stable dynamic inversion methods (and their adaptive counterparts), previous studies have considered the addition of a canard control surface to eliminate the occurrence of the unstable zero; however, the addition of a canard may negatively impact the design of the thermal protection system. In this paper, we present a methodology for robust nonlinear control of the rigid-body longitudinal hypersonic vehicle dynamics which employs only the elevator as aerodynamic control surface. The method reposes upon a nonlinear transformation of the equations-of-motion into the interconnection of systems in so-called feedback and feed-forward forms that allows the combination of high-gain and low-amplitude feedback, achieved through the use of saturated functions. Simulation results using the flexible vehicle model are presented to illustrate the effectiveness of the method.
american control conference | 2009
Andrea Serrani; Alicia Zinnecker; Lisa Fiorentini; Michael A. Bolender; David B. Doman
This paper presents the design of an adaptive flight control systems for constrained air-breathing hypersonic vehicle models. The proposed architecture comprises a robust adaptive nonlinear inner-loop controller, and a self-optimizing guidance scheme that shapes the reference to be tracked in order to avoid the occurrence of control input saturations. The scheme is explicitly designed to account for the presence of a state-dependent input saturation on the control loop for the vehicle longitudinal velocity, arising from physical limitations in the propulsion system. The approach is based on the integration of a previously-developed adaptive controller with a self-tuning pre-filter which shapes the reference command to maintain the control signal within feasible values. The reference command are left unaltered whenever there is sufficient control authority for stable tracking. Simulation results are provided to show the effectiveness of the method.
conference on decision and control | 2009
Lisa Fiorentini; Andrea Serrani
The design of a nonlinear robust controller for a non-minimum phase model of the longitudinal dynamics of an air-breathing hypersonic vehicle is presented in this work. When flight-path angle is selected as a regulated output and the elevator is the only control surface available for the pitch dynamics, longitudinal models of air-breathing hypersonic vehicle dynamics exhibit unstable zero-dynamics. The approach proposed in this paper uses a combination of small-gain arguments and adaptive control techniques for the design of a state-feedback controller that achieves asymptotic tracking of velocity and flight-path angle reference trajectories in spite of model uncertainties. The method reposes upon a suitable redefinition of the internal dynamics of a control-oriented model of the vehicle dynamics and uses a time-scale separation between the controlled variables to manage the peaking phenomenon occurring in the system. Simulation results on a full nonlinear vehicle model illustrate the effectiveness of the methodology.
conference on decision and control | 2008
Lisa Fiorentini; Andrea Serrani; Michael A. Bolender; David B. Doman
The design of a nonlinear robust adaptive controller for a flexible air-breathing hypersonic vehicle model is considered in this work. Due to the complexity of a first-principle model of the vehicle dynamics, for design and stability analysis a simplified model is adopted, which nonetheless retains the dominant features of the higher fidelity model, including non-minimum phase behavior, flexibility effects and strong coupling between the engine and flight dynamics. A combination of nonlinear sequential loop-closure and adaptive dynamic inversion is adopted to design a dynamic state-feedback controller that provides stable tracking of velocity and altitude reference trajectories and imposes a desired setpoint for the angle of attack. The proposed methodology addresses the issue of robustness with respect to both parametric model uncertainty, which naturally arises in adopting reduced-complexity models for control design, and dynamic perturbations due to the flexible dynamics. Simulation results on the full nonlinear model are included to show the effectiveness of the controller.
american control conference | 2011
Ahmed Al-Durra; Lisa Fiorentini; Marcello Canova; Stephen Yurkovich
One of the principal issues of low-temperature combustion modes is caused by the imbalances in the distribution of air and EGR across the cylinders, which affects the combustion process. Cylinder to cylinder variations lead to imbalances in the cylinder pressure, indicated torque, exhaust gas thermodynamic conditions and emissions. In principle, a cylinder-by-cylinder control approach could compensate for air, residuals and charge temperature imbalance. However, in order to fully benefit from closed-loop combustion control, a feedback from each engine cylinder would be necessary to reconstruct the pressure trace. Therefore, cylinder imbalance is an issue that can be detected only in a laboratory environment, wherein each engine cylinder is instrumented with a dedicated pressure transducer. This paper describes the framework and preliminary results of a model-based estimation approach to predict the individual pressure traces in a multi-cylinder engine from the output of a crankshaft speed sensor. The objective of the estimator is to reconstruct the complete pressure trace during an engine cycle with sufficient accuracy to allow for detection of cylinder to cylinder imbalances. Starting from a model of the engine crankshaft dynamics, a sliding mode observer is designed to estimate the cylinder pressure from the crankshaft speed fluctuation measurement. The results obtained by the estimator are compared with experimental data obtained on a four-cylinder Diesel engine.
advances in computing and communications | 2014
Quansheng Zhang; Lisa Fiorentini; Marcello Canova
The air conditioning system is one of the largest ancillary loads in passenger cars, with considerable effects on the vehicle fuel consumption. In this scenario, the optimization and control of the A/C system actuators has an important role in reducing the parasitic load of the A/C compressor on the engine.