Browsing by Author "Tasoujian, Shahin"
Now showing 1 - 2 of 2
- Results Per Page
- Sort Options
Item Gain-Scheduling Control of Air-Fuel Ratio in Spark Ignition Engines with Time-Delay Effects(2020-05) Tasoujian, Shahin; Grigoriadis, Karolos M.; Franchek, Matthew A.; Faghih, Rose T.This thesis addresses a variety of gain-scheduling control design schemes for the air-fuel ratio (AFR) control problem in spark ignition (SI) engines. Fueling strategy design has drawn significant attention in the past decades since it is essential for maximizing the fuel economy while minimizing harmful exhaust emissions. The fuel path of the SI engine, as well as the three-way catalyst (TWC) dynamics, have been captured by a continuous-time linear parameter-varying (LPV) system with varying time-delay. LPV systems are linear dynamical systems whose dynamic characteristics rely on a measurable scheduling parameter vector, where the scheduling parameter vector is used to capture the dynamics of time-varying systems. In the first part, a classical frequency-domain control method of parameter-varying loop-shaping is utilized to tackle the challenges imposed by the non-minimum phase (NMP) system and provide stability and desired performance. The second part of the thesis deals with the delay-dependent output-feedback LPV controller synthesis by using parameter-dependent Lyapunov-Krasovskii functionals. Stability conditions and a prescribed induced L2-norm in terms of the disturbance rejection performance are derived in a convex linear matrix inequalities (LMIs) setting. The proposed control methodology has a distinct advantage over previously developed methods as it results in less conservative results and able to handle LPV systems with arbitrary varying large time-delays. In the last part, a delay-dependent sampled-data LPV controller is proposed. Due to the discrete nature of the controllers, the main goal of this part is to find a discrete-time controller to satisfy the objectives. The interconnection of the continuous-time plant and a digital controller through converter devices forms a hybrid closed-loop configuration, which is challenging to analyze mathematically. The input-delay method has been employed to transfer the hybrid system into the continuous-time domain. The designed sampled-data gain-scheduled LPV controller is proposed to take the inter-sample behavior into account and is required to establish the closed-loop asymptotic stability and a prescribed level of performance for the closed-loop hybrid LPV system with an arbitrarily varying time delay and sampling time. Finally, conducted simulation scenarios assess the performance of the proposed digital controller in the sense of reference AFR tracking and disturbance attenuation.Item Linear Parameter Varying Control of Uncertain Time-Delay Systems with Applications to Automated Blood Pressure Regulation(2020-12) Tasoujian, Shahin; Grigoriadis, Karolos M.; Franchek, Matthew A.; Faghih, Rose T.; Song, Gangbing; Chen, ZhengThis dissertation examines the problem of real-time estimation and automated control of mean arterial blood pressure (MAP) response of a critical patient subject to the vasoactive drug infusion in emergency resuscitation scenarios. The proposed methodologies rely on the wealth of the system identification and feedback control theory and can provide reliable and efficient patient resuscitation tools via computerized drug administration. Therefore, such advanced resuscitation methods can reduce emergency care costs and significantly increase the survival chances by improving the patient's MAP regulation in an intensive care unit. In order to derive an appropriate mathematical description, a dynamic first-order linear time-varying model structure with varying parameters and time delay is employed to characterize the patient's complex physiological MAP response dynamics. In the first part of the dissertation, real-time estimation of the varying model parameters and delay is performed via a Bayesian-based multiple-model square-root cubature Kalman filtering (MMSRCKF) approach. The estimation results substantiate the effectiveness of the utilized identification method using experimental data. Next, two classical frequency-domain control design methods, namely, IMC-PID and parameter-varying loop-shaping approaches, are proposed and implemented to achieve desired MAP regulation in various simulation scenarios. The second part of the dissertation is devoted to the analysis and control synthesis of time-delayed linear parameter-varying (LPV) systems with norm-bounded parametric and/or time-delay uncertainties. LPV time-delay systems are linear dynamical systems whose dynamic characteristics rely on a measurable scheduling parameter vector, where the scheduling parameter vector is used systematically to capture the dynamics of time-varying and nonlinear systems. In order to reduce the design conservatism and handle the varying delay uncertainties, a Lyapunov-Krasovskii based approach is exercised, and by utilizing an improved parameter-dependent Lyapunov Krasovskii functional (LKF) candidate and applying an efficient cross-term bounding technique, the affine Jensen's inequality, sufficient stability and performance conditions are derived and formulated in terms of convex linear matrix inequality (LMI) framework. The final relaxed synthesis conditions are obtained to design a robust delay-dependent gain-scheduled controller, which guarantees closed-loop stability and minimizes disturbance amplification in terms of the induced L2-norm performance specification. The effectiveness of the proposed control design algorithms is assessed through the automated MAP regulation task, and the results are compared with the conventional control approaches in the literature. The final closed-loop simulation results confirm the potential and superiority of the adopted LPV methodologies.