242 research outputs found
Gain-Scheduling Controller Synthesis for Networked Systems with Full Block Scalings
This work presents a framework to synthesize structured gain-scheduled
controllers for structured plants that are affected by time-varying parametric
scheduling blocks. Using a so-called lifting approach, we are able to handle
several structured gain-scheduling problems arising from a nested inner and
outer loop configuration with partial or full dependence on the scheduling
block. Our resulting design conditions are formulated in terms of convex linear
matrix inequalities and permit to handle multiple performance objectives.Comment: 16 pages, 4 figure
State estimation, system identification and adaptive control for networked systems
A networked control system (NCS) is a feedback control system that has its control loop physically connected via real-time communication networks. To meet the demands of `teleautomation', modularity, integrated diagnostics, quick maintenance and decentralization of control, NCSs have received remarkable attention worldwide during the past decade. Yet despite their distinct advantages, NCSs are suffering from network-induced constraints such as time delays and packet dropouts, which may degrade system performance. Therefore, the network-induced constraints should be incorporated into the control design and related studies.
For the problem of state estimation in a network environment, we present the strategy of simultaneous input and state estimation to compensate for the effects of unknown input missing. A sub-optimal algorithm is proposed, and the stability properties are proven by analyzing the solution of a Riccati-like equation.
Despite its importance, system identification in a network environment has been studied poorly before. To identify the parameters of a system in a network environment, we modify the classical Kalman filter to obtain an algorithm that is capable of handling missing output data caused by the network medium. Convergence properties of the algorithm are established under the stochastic framework.
We further develop an adaptive control scheme for networked systems. By employing the proposed output estimator and parameter estimator, the designed adaptive control can track the expected signal. Rigorous convergence analysis of the scheme is performed under the stochastic framework as well
Unbiased Filtering for State and Unknown Input with Delay
International audienceIn this paper, we consider linear network systems with unknown inputs. We present an unbiased recursive algorithm that simultaneously estimates states and inputs. We focus on delay-left invertible systems with intrinsic delay l ≥ 1, where the input reconstruction is possible only by using outputs up to l time steps later in the future. By showing an equivalence with a descriptor system, we state conditions under which the time-varying filter converges to a stationary stable filter, involving the solution of a discrete-time algebraic Riccati equation
Resilient State Estimation for Nonlinear Discrete-Time Systems via Input and State Interval Observer Synthesis
This paper addresses the problem of resilient state estimation and attack
reconstruction for bounded-error nonlinear discrete-time systems with nonlinear
observations/ constraints, where both sensors and actuators can be compromised
by false data injection attack signals/unknown inputs. By leveraging
mixed-monotone decomposition of nonlinear functions, as well as affine parallel
outer-approximation of the observation functions, along with introducing
auxiliary states to cancel out the effect of the attacks/unknown inputs, our
proposed observer recursively computes interval estimates that by construction,
contain the true states and unknown inputs of the system. Moreover, we provide
several semi-definite programs to synthesize observer gains to ensure
input-to-state stability of the proposed observer and optimality of the design
in the sense of minimum gain.Comment: 7 page
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