• A Kalman-filtering derivation of simultaneous input and state estimation 

      Bitmead, Robert R.; Hovd, Morten; Abooshahab, Mohammad Ali (Journal article; Peer reviewed, 2019)
      Simultaneous input and state estimation algorithms are studied as particular limits of Kalman filtering problems. This admits interpretation of the algorithm properties and critical analysis of their claims to being partly ...
    • A note on establishing convergence in adaptive systems 

      Anfinsen, Henrik; Aamo, Ole Morten (Journal article; Peer reviewed, 2018)
      We present a new formulation of a convergence result for Lyapunov function candidates satisfying a differential inequality with integrable coefficients that often appears in adaptive control problems. Usually, Barbalat’s ...
    • Adaptive control of linear 2 x 2 hyperbolic systems 

      Anfinsen, Henrik; Aamo, Ole Morten (Journal article; Peer reviewed, 2018)
      We design two closely related state feedback adaptive control laws for stabilization of a class of 2 × 2 linear hyperbolic system of partial differential equations (PDEs) with constant but uncertain in-domain and boundary ...
    • Adaptive set-point regulation of linear 2x2 hyperbolic systems with application to the kick and loss problem in drilling 

      Holta, Haavard H. F.; Anfinsen, Henrik; Aamo, Ole Morten (Peer reviewed; Journal article, 2020)
      We study the kick and loss detection and attenuation problem in managed pressure drilling by modeling the well as a distributed parameter system. Two cases are considered, distinguished by whether down-hole pressure ...
    • An improved algorithm for combinatorial multi-parametric quadratic programming 

      Feller, Christian; Johansen, Tor Arne; Olaru, Sorin (Journal article; Peer reviewed, 2013)
      The goal of multi-parametric quadratic programming (mpQP) is to compute analytic solutions to parameter-dependent constrained optimization problems, e.g., in the context of explicit linear MPC. We propose an improved ...
    • Attitude Estimation by Multiplicative eXogenous Kalman Filter 

      Stovner, Bård Nagy; Johansen, Tor Arne; Fossen, Thor I.; Schjølberg, Ingrid (Journal article, 2018)
      This paper presents a novel attitude estimator called the multiplicative exogenous Kalman filter. The estimator inherits the stability properties of a nonlinear observer and the near-optimal steady-state performance of the ...
    • Boundary Observer Design for Hyperbolic PDE-ODE Cascade Systems 

      Hasan, Agus Ismail; Aamo, Ole Morten; Krstic, Miroslav (Journal article; Peer reviewed, 2016)
      The paper presents an observer design for a class of hyperbolic PDE–ODE cascade systems with a boundary measurement. The cascade systems consist of coupled PDEs, featuring one rightward and one leftward convecting first-order ...
    • Dual adaptive model predictive control 

      Heirung, Tor Aksel N.; Ydstie, Birger Erik; Foss, Bjarne Anton (Journal article; Peer reviewed, 2017)
      We present an adaptive dual model predictive controller (dmpc) that uses current and future parameter-estimation errors to minimize expected output error by optimally combining probing for uncertainty reduction with control ...
    • Explicit robustness and fragility margins for linear discrete systems with piecewise affine control law 

      Nguyen, Ngoc Anh; Olaru, Sorin; Rodriguez-Ayerbe, Pedro; Bitsoris, George; Hovd, Morten (Journal article; Peer reviewed, 2016)
      In this paper, we focus on the robustness and fragility problem for piecewise affine (PWA) control laws for discrete-time linear system dynamics in the presence of parametric uncertainty of the state space model. A generic ...
    • Leak detection, size estimation and localization in branched pipe flows 

      Anfinsen, Henrik; Aamo, Ole Morten (Peer reviewed; Journal article, 2022)
      We design a leak detection, size estimation and localization algorithm for a branched pipe system, requiring flow and pressure measurements to be taken at the inlet and outlet boundaries, only. By showing that the pipe ...
    • Low complexity constrained control using higher degree Lyapunov functions 

      Munir, Sarmad; Hovd, Morten; Olaru, Sorin (Journal article; Peer reviewed, 2018)
      Explicit Model Predictive Control often has a complex solution in terms of the number of regions required to define the solution and the corresponding memory requirement to represent the solution in the online implementation. ...
    • Observer based path following for underactuated marine vessels in the presence of ocean currents: A global approach 

      Belleter, Dennis Johannes Wouter; Maghenem, Mohamed; Paliotta, Claudio; Pettersen, Kristin (Journal article; Peer reviewed, 2019)
      In this paper a solution to the problem of following a curved path in the presence of a constant unknown ocean current disturbance is presented. We introduce a path variable that represents the curvilinear abscissa on the ...
    • On Kalman filtering with linear state equality constraints 

      Andersson, Leif Erik; Imsland, Lars Struen; Brekke, Edmund Førland; Scibilia, Francesco (Journal article; Peer reviewed, 2019)
      This article is concerned with the state estimation problem for linear systems with linear state equality constraints. We re-examine constrained Kalman filter variations and propose an alternative derivation of the optimal ...
    • On the accuracy of gradient estimation in extremum-seeking control using small perturbations 

      Haring, Mark; Johansen, Tor Arne (Journal article; Peer reviewed, 2018)
      In many extremum-seeking control methods, perturbations are added to the parameter signals to estimate derivatives of the objective function (that is, the steady-state parameter-to-performance map) in order to optimize the ...
    • On Uniform Semiglobal Exponential Stability (USGES) of Proportional Line-of-Sight Guidance Laws 

      Fossen, Thor I.; Pettersen, Kristin Ytterstad (Journal article; Peer reviewed, 2014-11)
      This paper presents a uniform semiglobal exponential stability (USGES) proof for a class of proportional line-of-sight (LOS) guidance laws used for vehicle path-following control. The LOS guidance law under consideration ...
    • Output feedback boundary control of 2x2 semilinear hyperbolic systems 

      Strecker, Timm; Aamo, Ole Morten (Journal article; Peer reviewed, 2017)
      We consider the control and state estimation of a class of 2x2 semilinear hyperbolic systems with actuation and sensing collocated at one boundary. Our approach exploits the dynamics on the characteristic lines of the ...
    • Output feedback boundary control of heterodirectional semilinear hyperbolic systems 

      Strecker, Timm; Aamo, Ole Morten; Cantoni, Michael (Peer reviewed; Journal article, 2020)
      We solve the problem of stabilizing a general class of 1-d semilinear hyperbolic systems with an arbitrary number of states convecting in each direction and with the actuation and sensing restricted to one boundary. The ...
    • Predictive feedback boundary control of semilinear and quasilinear 2 × 2 hyperbolic PDE–ODE systems 

      Strecker, Timm; Aamo, Ole Morten; Cantoni, Michael (Peer reviewed; Journal article, 2022)
      We present a control design for semilinear and quasilinear 2 × 2 hyperbolic partial differential equations with the control input at one boundary and a nonlinear ordinary differential equation coupled to the other. The ...
    • Quadratic programming with ramp functions and fast online QP-MPC solutions 

      Valmorbida, Giorgio; Hovd, Morten (Peer reviewed; Journal article, 2023)
      A novel method is proposed for solving quadratic programming problems arising in model predictive control. The method is based on an implicit representation of the Karush–Kuhn–Tucker conditions using ramp functions. The ...
    • Simultaneous input & state estimation, singular filtering and stability 

      Abooshahab, Mohammad Ali; Alyaseen, Mohammed M.J.; Bitmead, Robert R.; Hovd, Morten (Peer reviewed; Journal article, 2021)
      Input estimation is a signal processing technique associated with deconvolution of measured signals after filtering through a known dynamic system. Kitanidis and others extended this to the simultaneous estimation of the ...