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We recently proposed to accelerate online MPC calculations by detecting and removing inactive constraints from the online optimization problems as a function of the current initial state. A number of variants of constraint removal (CR) have been explored, ranging from detecting inactive constraints based on precomputed regions of activity or approximations thereof to online methods that do not require...
Model Predictive Control (MPC) requires the online solution of an Optimal Control Problem (OCP) at each sampling time. Efficient online algorithms such as the Real-Time Iteration (RTI) scheme have been developed for real-time MPC implementations even for fast nonlinear dynamic systems. The RTI framework is based on direct Multiple Shooting (MS) for centralized systems. Distributed Multiple Shooting...
This paper deals with the nonlinear longitudinal and lateral combined control for the vehicle based on a simple, fast, nonlinear dicrete time control approach. An approximate numerical one-step time discretization of the nonlinear plant model behavior is used to find out the outputs of controller that minimize the distance between the plant output and a linear system as closed loop reference, leading...
The link between linear model predictive control (MPC) and parametric linear/quadratic programming has reached maturity in terms of the characterization of the structural properties and the numerical methods available for the effective resolution. The computational complexity is one of the current bottlenecks for these control design methods and inverse optimality has been recently shown to provide...
In this paper, the problem of fractional-order proportional-integral-derivative (FOPID) controller tuning for fractional-order first-order plus dead time plants (FFOPDT) is considered. The designed controller must fulfill the prescribed specifications in the frequency domain. To this end, the fractional orders of the integrator and differentiator components are selected using a set of rules based...
This paper addresses the problem of designing static feedback controllers for 2D mixed continuous-discrete-time systems via linear matrix inequalities (LMIs). It is shown that a necessary and sufficient condition can be obtained by solving two LMI problems. The first LMI problem aims at determining a polynomial whose positivity domain corresponds to stabilizing controllers. The second LMI problem...
In this paper an averaging result for switched systems whose modes are represented by means of differential algebraic equations (DAEs) is presented. Homogeneous switched DAEs with periodic switchings between two modes are considered. It is proved that a (switched) averaged system can be defined also in the presence of state jumps whose amplitude does not decrease with the increasing of the switching...
We propose a hyperbolicity analysis method for multiple equilibria of a nonlinear system with dynamic uncertainties. Since dynamic uncertainties alter the location and even the existence of equilibria, it is difficult to evaluate the hyperbolicity of equilibria for such a system. In this paper, we provide an analysis method to determine whether all equilibria robustly maintain their hyperbolicity...
This paper demonstrates a discrete-time state observer for a 3DOF helicopter subject to unknown perturbations. The observer is based on a very recent second order sliding mode scheme [12], which is robust in spite of uncertainties and perturbations, ensures finite time convergence to boundary layer, reduces the chattering, increases estimation accuracy and does not require the knowledge of the bound...
This paper analyses discrete-time switched systems in which a control engineer designs each mode so that performance guarantees are met. Given this setting, our objective is then to identify the set of mode transitions so that stability is guaranteed under arbitrary switching. Namely, our specific objective is to identify the stability graph associated with a given switching system. These systems...
We study in this paper a dynamic berth and quay cranes allocation strategy in general seaport container terminals. We develop a dynamical model that describes the operation of berthing process with multiple discrete berthing positions and multiple quay cranes. Based on the proposed model, we develop a dynamic allocation strategy using the model predictive control (MPC) paradigm. The proposed strategy...
We describe a new algorithm for trajectory optimization of mechanical systems. Our method combines pseudo-spectral methods for function approximation with variational discretization schemes that exactly preserve conserved mechanical quantities such as momentum. We thus obtain a global discretization of the Lagrange-d'Alembert variational principle using pseudo-spectral methods. Our proposed scheme...
In this study, diagonal dominance of two input two output systems are discussed by considering the standard and weighted diagonal dominance conditions separately. In addition, sufficient conditions using static diagonal controllers are derived for fixed frequencies. Derived results can be easily extended for a given frequency range. An algorithm is proposed to determine static controller gain regions...
This work is devoted to the construction of feedback laws which guarantee the robust global exponential stability of the uncongested equilibrium point for general discrete-time freeway models. The feedback construction is based on a control Lyapunov function approach and exploits certain important properties of freeway models. The developed feedback laws are tested in simulation. A comparison with...
This paper proposes a distributed framework for optimal control of vehicles in transportation networks. The objective is to reduce the balanced fuel consumption and travel time through hybrid control on speed limit and ramp metering rate. The dual decomposition theory associated with the subgradient method is then applied in order to decompose the optimal control problem into a series of suboptimal...
With model predictive control (MPC) becoming a viable approach for advanced feedback control at very fast sampling times, a plethora of methods for solving quadratic programming (QP) problems on embedded computing hardware has been proposed. While most of these methods seem to be useful and superior to competing approaches on particular problem instances, very little effort has been put into a proper...
In this paper we combine the quadratic approximation approach used in derivative-free optimization (DFO) with iterative gradient-modification optimization (IGMO) to formulate an efficient scheme for iterative real-time optimization (RTO) under model uncertainty. By combining the robustness of the DFO approach to noisy data with the convergence to the true optimum of the IGMO using empirical gradients,...
This paper introduces a learning-based robust control algorithm that provides robust stability and performance guarantees during learning. The approach uses Gaussian process (GP) regression based on data gathered during operation to update an initial model of the system and to gradually decrease the uncertainty related to this model. Embedding this data-based update scheme in a robust control framework...
Heat pumps have recently received increasing interest due to green energy initiatives and increasing energy prices. In this paper, a nonlinear dynamic model of a single-effect LiBr-water absorption cycle heat pump is derived for simulation and control design purposes. The model is based on an actual heat pump located at a larger district heating plant. The model is implemented in Modelica and is based...
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