473 research outputs found
Integral control of port-Hamiltonian systems: non-passive outputs without coordinate transformation
In this paper we present a method for the addition of integral action to
non-passive outputs of a class of port-Hamiltonian systems. The proposed
integral controller is a dynamic extension, constructed from the open loop
system, such that the closed loop preserves the port-Hamiltonian form. It is
shown that the controller is able to reject the effects of both matched and
unmatched disturbances, preserving the regulation of the non-passive outputs.
Previous solutions to this problem have relied on a change of coordinates
whereas the presented solution is developed using the original state vector
and, therefore, retains its physical interpretation. In addition, the resulting
closed loop dynamics have a natural interpretation as a Control by
Interconnection scheme.Comment: 8 pages, 2 figure
An energy-based state observer for dynamical subsystems with inaccessible state variables
This work presents an energy-based state estimation formalism for a class of dynamical systems with inaccessible/ unknown outputs, and systems at which sensor utilization is impractical, or when measurements can not be taken. The
power-conserving physical interconnections among most of the dynamical subsystems allow for power exchange through their power ports. Power exchange is conceptually considered as information exchange among the dynamical subsystems and further utilized to develop a natural feedback-like information
from a class of dynamical systems with inaccessible/unknown outputs. This information is used in the design of an energybased state observer. Convergence stability of the estimation error for the proposed state observer is proved for systems with linear dynamics. Furthermore, robustness of the convergence stability is analyzed over a range of parameter deviation and model uncertainties. Experiments are conducted on a dynamical system with a single input and multiple inaccessible outputs (Fig. 1) to demonstrate the validity of the proposed energybased state estimation formalism
An Energy-Based State Observer for Dynamical Subsystems with Inaccessible State Variables
This work presents an energy-based state estimation formalism for a class of dynamical systems with inaccessible/ unknown outputs, and systems at which sensor utilization is impractical, or when measurements can not be taken. The power-conserving physical interconnections among most of the dynamical subsystems allow for power exchange through their power ports. Power exchange is conceptually considered as information exchange among the dynamical subsystems and further utilized to develop a natural feedback-like information from a class of dynamical systems with inaccessible/unknown outputs. This information is used in the design of an energybased state observer. Convergence stability of the estimation error for the proposed state observer is proved for systems with linear dynamics. Furthermore, robustness of the convergence stability is analyzed over a range of parameter deviation and model uncertainties. Experiments are conducted on a dynamical system with a single input and multiple inaccessible outputs (Fig. 1) to demonstrate the validity of the proposed energybased state estimation formalism
Putting energy back in control
A control system design technique using the principle of energy balancing was analyzed. Passivity-based control (PBC) techniques were used to analyze complex systems by decomposing them into simpler sub systems, which upon interconnection and total energy addition were helpful in determining the overall system behavior. An attempt to identify physical obstacles that hampered the use of PBC in applications other than mechanical systems was carried out. The technique was applicable to systems which were stabilized with passive controllers
Some results on disturbance attenuation for Hamiltonian systems via direct discrete-time design
The disturbance attenuation and robust disturbance attenuation problems for Hamiltonian systems in the discrete-time setting are considered and some new results are presented. The new results are derived utilizing the recently presented dissipativity equality obtained by adding the dissipation rate function to the classical dissipativity inequality. A selection of the dissipation rate function yields new results. These results include a condition on the dissipation structure of the system to achieve the desired disturbance attenuation level and gives direct construction of optimal control laws for any desired disturbance attenuation level. The results remove the need to solve HamiltonâJacobiâIsaacs inequalities
Robust energy shaping for mechanical systems with dissipative forces and disturbances
This paper presents a novel energy shaping-based integral action for mechanical systems with unknown dissipative forces and matched disturbances. The proposed approach builds on the simultaneous interconnection and damping as- signment method and takes advantage of the representation of the dissipative forces in the port-Hamiltonian dynamics. We consider dissipative forces that cannot be written in the classical dissipation structure of the port-Hamiltonian systems. We show that the proposed design ensures the stability of the equilibrium and is robust against dissipative force uncertainty, and rejects constant matched disturbances. Two case studies are presented, and simulation results show the closed-loop performance
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