1,721,012 research outputs found
Prove impulsive per la caratterizzazione della dinamica di temperatura del collettore solare
No full textTech. Rep
Robust Minimum-Time Control of Nonlinear Discrete-Time Dynamical Systems with Non-Robustly Controllable Target Sets
No full textThis work deals with the analysis and the design of
minimum-time control laws for a class of nonlinear discrete-time
dynamical systems characterized by -continuous transitionmaps
and bounded control inputs. In the paper, it is shown that the reachability
properties of the target set, even if not robust positively controllable
in one state transition, can be exploited to assess the existence
of a robust positively controllable set including the target in
its interior. This result allows the formulation of a robustified minimum-
time control policy, based on iterated online optimizations
and guaranteeing the ultimate boundedness of the state-trajectories
in the presence of bounded uncertainties, even if the target set
is not robust positively controllable
Robust Set Invariance under Controlled Nonlinear Dynamics with Application to Robust RH Control
No full textAdaptive time-warped control of molten salt distributed collector solar fields
No full textThis paper concerns the temperature control of a new class of distributed collectors solar fields, which employ molten salt as heat transfer fluid (HTF). Distinctive characteristics of these plants are the high operating temperatures, close to the thermal limits of receiver pipes, and the high solidification temperature of HTF. By means of a novel hybrid adaptive control scheme, based on the Unscented Kalman Filter and on a time-warped predictive controller, the HTF temperature can be effectively controlled within prescribed constraints also in presence of uncertainty in model parameters and faults on collectors
Networked Predictive Control of Constrained Nonlinear Systems: Recursive Feasibility and Input-to-State Stability Analysis
No full textAn input-to-state stabilizing discrete-time adaptive control scheme for concentrating solar power systems
No full textThe development of advanced solar thermal parabolic trough collectors fields for electrical power generation calls for the conception of simple but effective temperature control strategies capable to cope with the nonlinearities and the uncertainties that typically affect this kind of plants, which are mainly due to the variability of thermal and optical parameters among the collector modules. For plants in which multiple temperature measurements are available for each string of collectors, as in the case of the molten-salt technology under exam, an adaptive control strategy is proposed. It relies on the combined use of a discrete-time nonlinear model-based controller with an on-line parameter adaptation mechanism based on error-projection. Under a persistency of excitation assumption, the input-to-state stability of the resulting c-l system with respect to bounded unstructured uncertainties can be proven. Simulation results show that the proposed control policy allows to effectively control the plant in various operating scenarios
Robust Parametric Identification of Sinusoidal Signals: an Input-to-State Stability Approach
No full textModeling and control of concentrating solar power systems: a discrete-time adaptive scheme for temperature control in molten salt solar collectors fields.
No full textMany different solutions have been developed in the last few years to concentrate the solar radiation for generating electrical power. Among the existing thermo-electrical Concentrating Solar Power technologies, parabolic trough fields are the most mature and one of the most suited for the application to large-scale plants. In this framework, the use of molten salts as Heat Transfer Fluid can provide major improvements to the parabolic trough technology. On the other side, the development of advanced molten salts plants calls for the conception of simple but effective temperature control policies able to cope with hard constraints and with the uncertainties that typically affect solar trough fields, which are mainly related to the variability of thermal and optical parameters among the collector modules. For plants in which multiple temperature measurements are available for each string of collectors, as in the case of the molten-salt technology under examination, an adaptive control strategy is proposed, which is aimed at satisfying the strict control requirements posed by the considered class of solar plants. The devised strategy relies on the combined use of a discrete-time nonlinear modelbased controller with an on-line parameter adaptation mechanism. Simulation results show that the proposed control policy, together with a specific constraints-handling strategy, allows one to effectively control the plant in various operating scenarios
Adaptive Task-Space Metal Strip-Flatness Control in cold Multi-roll Mill Stands
No full textThe automatic flatness control system applied to cold multi-roll mills for the production of metal strips
has been subject of research efforts in many directions since the last 30 years. An innovative multivariable
control approach for this application context is presented by means of which potential stability problems
of controllers based on least mean squares are addressed. The proposed methodology decomposes
the array of strip-elongation measurements produced by a conventional shape-meter into orthogonal
components corresponding to the main actuator directions in order to reduce the dimensionality of the
problem. Then, the control actions are computed by solving a prioritized constrained quadratic optimization
problem. In this regard, the control problem is reformulated within a task-space control formalism
– originally conceived in the robotics context – for which very efficient solution procedures do exist.
Furthermore, in order to account for the model uncertainties that typically affects this kind of systems,
the model of the process is adapted on-line by a numerically robust technique. The adaptive task-space
flatness control scheme dealt with in the paper has been already commissioned in several installations
having different actuator configurations and the experimental results shows its effectiveness and its easy
configurability
Robust Sinusoid Identification with Structured and Unstructured Measurement Uncertainties
No full textIn this note a globally stable methodology is proposed to estimate
the frequency, phase, and amplitude of a sinusoidal signal affected
by additive structured and bounded unstructured disturbances. The structured
disturbances belong to the class of time-polynomial signals incorporating
both bias and drift phenomena. Stability and robustness results are
given by resorting to Input-to-State stability arguments. Simulation comparative
results show the effectiveness of the proposed technique
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