196 research outputs found
A hierarchical MPC scheme for interconnected systems
This paper describes a hierarchical control scheme for interconnected
systems. The higher layer of the control structure is designed with robust
Model Predictive Control (MPC) based on a reduced order dynamic model of the
overall system and is aimed at optimizing long-term performance, while at the
lower layer local regulators acting at a higher frequency are designed for the
full order models of the subsystems to refine the control action. A simulation
experiment concerning the control of the temperature inside a building is
reported to witness the potentialities of the proposed approach
Plug-and-Play Model Predictive Control based on robust control invariant sets
In this paper we consider a linear system represented by a coupling graph
between subsystems and propose a distributed control scheme capable to
guarantee asymptotic stability and satisfaction of constraints on system inputs
and states. Most importantly, as in Riverso et al., 2012 our design procedure
enables plug-and-play (PnP) operations, meaning that (i) the addition or
removal of subsystems triggers the design of local controllers associated to
successors to the subsystem only and (ii) the synthesis of a local controller
for a subsystem requires information only from predecessors of the subsystem
and it can be performed using only local computational resources. Our method
hinges on local tube MPC controllers based on robust control invariant sets and
it advances the PnP design procedure proposed in Riverso et al., 2012 in
several directions. Quite notably, using recent results in the computation of
robust control invariant sets, we show how critical steps in the design of a
local controller can be solved through linear programming. Finally, an
application of the proposed control design procedure to frequency control in
power networks is presented
Plug-and-Play Decentralized Model Predictive Control
In this paper we consider a linear system structured into physically coupled
subsystems and propose a decentralized control scheme capable to guarantee
asymptotic stability and satisfaction of constraints on system inputs and
states. The design procedure is totally decentralized, since the synthesis of a
local controller uses only information on a subsystem and its neighbors, i.e.
subsystems coupled to it. We first derive tests for checking if a subsystem can
be plugged into (or unplugged from) an existing plant without spoiling overall
stability and constraint satisfaction. When this is possible, we show how to
automatize the design of local controllers so that it can be carried out in
parallel by smart actuators equipped with computational resources and capable
to exchange information with neighboring subsystems. In particular, local
controllers exploit tube-based Model Predictive Control (MPC) in order to
guarantee robustness with respect to physical coupling among subsystems.
Finally, an application of the proposed control design procedure to frequency
control in power networks is presented.Comment: arXiv admin note: text overlap with arXiv:1210.692
Learning-based predictive control for linear systems: a unitary approach
A comprehensive approach addressing identification and control for
learningbased Model Predictive Control (MPC) for linear systems is presented.
The design technique yields a data-driven MPC law, based on a dataset collected
from the working plant. The method is indirect, i.e. it relies on a model
learning phase and a model-based control design one, devised in an integrated
manner. In the model learning phase, a twofold outcome is achieved: first,
different optimal p-steps ahead prediction models are obtained, to be used in
the MPC cost function; secondly, a perturbed state-space model is derived, to
be used for robust constraint satisfaction. Resorting to Set Membership
techniques, a characterization of the bounded model uncertainties is obtained,
which is a key feature for a successful application of the robust control
algorithm. In the control design phase, a robust MPC law is proposed, able to
track piece-wise constant reference signals, with guaranteed recursive
feasibility and convergence properties. The controller embeds multistep
predictors in the cost function, it ensures robust constraints satisfaction
thanks to the learnt uncertainty model, and it can deal with possibly
unfeasible reference values. The proposed approach is finally tested in a
numerical example
LSTM Neural Networks: Input to State Stability and Probabilistic Safety Verification
The goal of this paper is to analyze Long Short Term Memory (LSTM) neural
networks from a dynamical system perspective. The classical recursive equations
describing the evolution of LSTM can be recast in state space form, resulting
in a time-invariant nonlinear dynamical system. A sufficient condition
guaranteeing the Input-to-State (ISS) stability property of this class of
systems is provided. The ISS property entails the boundedness of the output
reachable set of the LSTM. In light of this result, a novel approach for the
safety verification of the network, based on the Scenario Approach, is devised.
The proposed method is eventually tested on a pH neutralization process.Comment: Accepted for Learning for dynamics & control (L4DC) 202
Plug-and-play distributed state estimation for linear systems
This paper proposes a state estimator for large-scale linear systems
described by the interaction of state-coupled subsystems affected by bounded
disturbances. We equip each subsystem with a Local State Estimator (LSE) for
the reconstruction of the subsystem states using pieces of information from
parent subsystems only. Moreover we provide conditions guaranteeing that the
estimation errors are confined into prescribed polyhedral sets and converge to
zero in absence of disturbances. Quite remarkably, the design of an LSE is
recast into an optimization problem that requires data from the corresponding
subsystem and its parents only. This allows one to synthesize LSEs in a
Plug-and-Play (PnP) fashion, i.e. when a subsystem gets added, the update of
the whole estimator requires at most the design of an LSE for the subsystem and
its parents. Theoretical results are backed up by numerical experiments on a
mechanical system
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