Topics in nonlinear control.: Output Feedback Stabilization and Control of Positive Systems
MetadataVis full innførsel
The contributions of this thesis are in the area of control of systems with nonlinear dynamics. The thesis is divided into three parts. The two first parts are similar in the sense that they both consider output feedback of rather general classes of nonlinear systems, and both approaches are based on mathematical programming (although in quite different ways). The third part contains a state feedback approach for a specific system class, and is more application oriented. The first part treats control of systems described by nonlinear difference equations, possibly with uncertain terms. The system dynamics are represented by piecewise affine difference inclusions, and for this system class, piecewise affine controller structures are suggested. Controller synthesis inequalities for such controller structures are given in the form of Bilinear Matrix Inequalities (BMIs). A solver for the BMIs is developed. The main contribution is to the output feedback case, where an observer-based controller structure is proposed. The theory is exemplified through two examples. In the second part the output feedback problem is examined in the setting of Nonlinear Model Predictive Control (NMPC). The state space formulation of NMPC is inherently a state feedback approach, since the state is needed as initial condition for the prediction in the controller. Consequently, for output feedback it is natural to use observers to obtain estimates of the state. A high gain observer is applied for this purpose. It is shown that for several existing NMPC schemes, the state feedback stability properties ``semiglobally'' hold in the output feedback case. The theory is illuminated with a simple example. Finally, a state feedback controller for a class of positive systems is proposed. Convergence of the state to a certain subset of the first orthant, corresponding to a constant ``total mass'' (interpreting states as masses) is obtained. Conditions are given under which convergence to this set implies asymptotic stability of an equilibrium. Simple examples illustrate some properties of the controller. Furthermore, the control strategy is applied to the stabilization of a gas-lifted oil well, and simulations on a rigorous multi-phase dynamic simulator of such a well demonstrate the controller performance.
UtgiverFakultet for informasjonsteknologi, matematikk og elektroteknikk
SerieDr. ingeniøravhandling, 0809-103X; 2002:112
Viser innførsler beslektet ved tittel, forfatter og emneord.
Well control with Controlled Mud Pressure: Reviewing AGR’s well control procedures for the CMP system, analyzing and comparing with conventional well-control procedures, possible impact of technology. Hansen, Morten (Master thesis, 2011)Dual Gradient Drilling (DGD) are a portfolio of drilling systems that in various ways pumpreturns from the well through a mud return line (MRL) from the seafloor, or somewhere between the seafloor and the rig floor. Two ...
ALTERNATIVE AND FLEXIBLE CONTROL METHODS FOR ROBOTIC MANIPULATORS: On the challenge of developing a flexible control architecture that allows for controlling different manipulators Sanfilippo, Filippo (Doctoral thesis at NTNU;2015:192, Doctoral thesis, 2015)Robotic arms and cranes show some similarities in the way they operate and in the way they are designed. Both have a number of links serially attached to each other by means of joints that can be moved by some type of ...
Stabilizing control and controllability. Control solutions to avoid slug flow in pipeline-riser systems Storkaas, Espen (Doktoravhandlinger ved NTNU, 1503-8181; 2005:97, Doctoral thesis, 2005)Riser slugging is a flow regime that can occur in multiphase pipeline-riser systems, and is characterized by severe flow and pressure oscillations. The irregular flow caused by riser slugging can cause large operational ...