Oguzhan Cifdaloz - Profile on Academia.edu (original) (raw)

Papers by Oguzhan Cifdaloz

TURKISH JOURNAL OF ELECTRICAL ENGINEERING & COMPUTER SCIENCES, 2021

In this paper, a method to construct the line of sight rate of a target with a roll-pitch gimbal ... more In this paper, a method to construct the line of sight rate of a target with a roll-pitch gimbal and tracker is described. Construction of line-of-sight rate is performed via utilizing a virtual pitch-yaw gimbal. Kinematics of both the roll-pitch and pitch-yaw gimbals are described. A dynamical model for the roll-pitch gimbal is developed, and a nested control structure is designed to control the angular rates and line of sight angles. A kinematic model of the tracker is developed and a tracker controller is designed to keep the target in the field of view. Conversion equations between roll-pitch and pitch-yaw gimbal configurations are provided. Finally, constructed line of sight rates are compared to true line of sight rates via simulations. Obtained results indicate that the constructed line of sight rates pertaining to a target satisfactorily converge to the actual line of sight rates.

GAZI UNIVERSITY JOURNAL OF SCIENCE, 2021

• Control systems provides robust and implementable solutions to management of renewable resource... more • Control systems provides robust and implementable solutions to management of renewable resources. • Optimal solution to management problem is difficult to implement and vulnerable to uncertainties. • Well-established tools and methods of control systems discipline proposes alternative solutions.

Challenges and Paradigms in Applied Robust Control, 2011

A critical challenge faced by sustainability science is to develop robust strategies to cope with... more A critical challenge faced by sustainability science is to develop robust strategies to cope with highly uncertain social and ecological dynamics. The increasing intensity with which human societies utilize (limited) natural resources is fueling the global debate and urging the development of resource management methodologies/policies to effectively deal with very demanding socio-bio-economical issues. Unfortunately, despite concerted efforts by governments, many natural resources continue to be poorly managed.

AIAA Guidance, Navigation and Control Conference and Exhibit, 2008

Most of the cases of rupture of uterus occurs in the third trimester of pregnancy or during labou... more Most of the cases of rupture of uterus occurs in the third trimester of pregnancy or during labour but here we report a thirty five year old women G3, P1+1, LCB 10 years back , mode of delivery by LSCS was admitted in MG ward of Malda medical college, West Bengal, India at 16 weeks of pregnancy with complain of acute abdominal pain, vomiting with clinical sign of shock without vaginal bleeding. Haemoperitoneum and dead fetus outside the uterus was discovered by urgent USG of whole abdomen. Emergency laparotomy was carried out and it revealed haemoperitoneum due to spontaneous rupture of uterine fundus through which fetus and placenta were extruded in peritoneal cavity. Though spontaneous fundal rupture is very rare in early second trimester of pregnancy, it should be taken into consideration in the differential diagnosis of acute abdomen during pregnancy specially if there is predisposing factors.

Proceedings of the National Academy of Sciences, 2007

A critical challenge faced by sustainability science is to develop strategies to cope with highly... more A critical challenge faced by sustainability science is to develop strategies to cope with highly uncertain social and ecological dynamics. This article explores the use of the robust control framework toward this end. After briefly outlining the robust control framework, we apply it to the traditional Gordon–Schaefer fishery model to explore fundamental performance–robustness and robustness–vulnerability trade-offs in natural resource management. We find that the classic optimal control policy can be very sensitive to parametric uncertainty. By exploring a large class of alternative strategies, we show that there are no panaceas: even mild robustness properties are difficult to achieve, and increasing robustness to some parameters (e.g., biological parameters) results in decreased robustness with respect to others (e.g., economic parameters). On the basis of this example, we extract some broader themes for better management of resources under uncertainty and for sustainability scie...

Environmental Modeling & Assessment, 2010

This paper presents a framework for the study of policy implementation in highly uncertain natura... more This paper presents a framework for the study of policy implementation in highly uncertain natural resource systems in which uncertainty cannot be characterized by probability distributions. We apply the framework to parametric uncertainty in the traditional Gordon-Schaefer model of a fishery to illustrate how performance can be sacrificed (traded-off) for reduced sensitivity and hence increased robustness, with respect to model parameter uncertainty. With sufficient data, our robustness-vulnerability analysis provides tools to discuss policy options. When less data are available, it can be used to inform the early stages of a learning process. Several key insights emerge from this analysis: (1) the classic optimal control policy can be very sensitive to parametric uncertainty, (2) even mild robustness properties are difficult to achieve for the simple Gordon-Schaefer model, and (3) achieving increased robustness with respect to some parameters (e.g., biological parameters) necessarily results in increased

2009 American Control Conference, 2009

In this paper, we examine the control of a scramjet-powered hypersonic vehicle with significant a... more In this paper, we examine the control of a scramjet-powered hypersonic vehicle with significant aeroelastic-propulsion interactions. Such vehicles are characterized by open loop unstable non-minimum phase dynamics, low frequency aero-elastic modes, significant coupling, and hard constraints (e.g. control surface deflection limits, thrust margin). Within this paper, attention is placed on maintaining acceptable closed loop performance (i.e. tracking of speed and flight path angle commands) while satisfying hard control surface deflection constraints as well as stoichiometrically normalized fuel-equivalency-ratio (FER) margin constraints. Control surface constraints are a consequence of maximum permissible aerodynamic loading. FER margin constraints are a consequence of thermal choking (i.e. unity combustor exit Mach number) and the fact that thrust loss may not be captured for FER greater than unity. Such limits are particularly important since the vehicle is open loop unstable and "saturation" can result in instability. To address these issues, one can design conservative (i.e. less aggressive or lower bandwidth) controllers that maintain operation below saturation levels for anticipated reference commands (and disturbances). Doing so, however, unnecessarily sacrifices performance -particularly when small reference commands are issued. Within this paper, the above issues are addressed using generalized predictive control (GPC). A 3DOF longitudinal model for a generic hypersonic vehicle, which includes aero-elastic-propulsion interactions, is used to illustrate the ideas.

H -infinity mixed-sensitivity optimization for infinite dimensional plants subject to convex constraints

Management of Open-Access Renewable Resources with Depensation Dynamics: Control Systems Perspective

2021 8th International Conference on Electrical and Electronics Engineering (ICEEE)

Renewable resources are being over exploited at an increasing rate. Institutions/governments are ... more Renewable resources are being over exploited at an increasing rate. Institutions/governments are compelled to devise effective policies and strategies to sustainably manage renewable resources under social, ecological and environmental pressures that stem from increasing demand, model uncertainties, disturbances, and measurement errors. Open-access policies to harvest renewable resources are still widely used around the world. They are mildly regulated by implementing landing quotas, defining harvesting seasons, and/or constraining the technology used for harvesting. In many parts of the world, including the regions that are highly developed, open-access fisheries are failing. In this paper, management of an open-access renewable resource (fishery) with depensation dynamics is formulated as a control systems problem and a strategy to sustainably manage the renewable resource is proposed. First, dynamics of an unregulated open-access fishery is described and its ulnerabilities are stated. Then, an easy-to-implement regulation strategy based on classical control systems ideas is proposed and its robustness characteristics are provided. The management policy (control law) is implemented via manipulating economic variables, i.e. by adjusting the (opportunity) cost of harvesting. An agent-based model is used to model the resource exploiters (i.e. fishermen). It is shown that a classical control law can be used to effectively manage an open access fishery subject to sampling effects.

Towards gain-scheduled H∞ control design for a tilt-wing aircraft

Page 1. Towards Gain-Scheduled H∞ Control Design for a Tilt-Wing Aircraft David R. Mix, John S. K... more Page 1. Towards Gain-Scheduled H∞ Control Design for a Tilt-Wing Aircraft David R. Mix, John S. Koenig, Karen M. Linda, Oguzhan Cifdaloz, Valana L. Wells, and Armando A. Rodriguez Index Terms:Tilt-Wing, Rotary-Wing ...

Going Beyond Panaceas Special Feature: Panaceas, uncertainty, and the robust control framework in sustainability science

Pnas, 2007

Proceedings of the 44th IEEE Conference on Decision and Control, 2005

In many applications, it is essential to limit control signals. This paper presents methods that ... more In many applications, it is essential to limit control signals. This paper presents methods that process accessible system signals (e.g., plant and compensator states, reference commands) to limit control signals. In contrast to "classical techniques" which limit variables by unnecessarily reducing control system bandwidth, the proposed methods limit variables in a nonconservative manner, reducing bandwidth only when necessary. A fundamental contribution of this work is that the methods presented are applicable to linear parameter varying (LPV) and quasi-LPV plants and controllers. The methods presented rely on appropriately "scaling back" key signals. The methods are conservative in that they are applicable to "slowly varying" LPV systems. Although the methods require access to all internal closed loop system state variables, one could use an appropriately designed LPV state estimator, if necessary. The Error Governer (EG) methods are applied to an LPV missile autopilot example.

American Control Conference, 2005

This paper shows how convex optimization may be used to design near-optimal finite-dimensional co... more This paper shows how convex optimization may be used to design near-optimal finite-dimensional compensators for stable linear time invariant (LTI) infinite dimensional plants. The infinite dimensional plant is approximated by a finite dimensional transfer function matrix. The Youla parameterization is used to parameterize the set of all stabilizing LTI controllers and formulate a weighted mixed-sensitivity H∞ optimization that is convex

H^∞ mixed-sensitivity optimization for distributed parameter plants subject to convex constraints

2007 46th IEEE Conference on Decision and Control, 2007

This paper focuses on Hinfin near-optimal finite- dimensional compensator design for linear time ... more This paper focuses on Hinfin near-optimal finite- dimensional compensator design for linear time invariant (LTI) distributed parameter plants subject to convex constraints. The distributed parameter plant is first approximated by a finite dimensional approximant. For unstable plants, the coprime factors are approximated by their finite dimensional approximants. The Youla parameterization is then used to parameterize the set of all stabilizing

Robust H∞ Gain-Scheduled Conversion for a Tilt-Wing Rotorcraft

Conference on Decision and Control, 2006

This paper describes the development an analysis of robust, multi-variable H∞ control systems for... more This paper describes the development an analysis of robust, multi-variable H∞ control systems for the conversion of the high-speed autonomous rotorcraft vehicle (HARVee), an experimental tilt-wing aircraft. Tilt-wing aircraft combine the high-speed cruise capabilities of a conventional airplane with the vertical takeoff and station keeping abilities of a helicopter by rotating their wings at the fuselage. Changing between cruise and

H∞ Hover-to-Cruise Conversion for a Tilt-Wing Rotorcraft

Decision and Control, …

Page 1. H∞ Hover-to-Cruise Conversion for a Tilt-Wing Rotorcraft Jeffrey J. Dickeson, David R. Mi... more Page 1. H∞ Hover-to-Cruise Conversion for a Tilt-Wing Rotorcraft Jeffrey J. Dickeson, David R. Mix, John S. Koenig, Karen M. Linda, Oguzhan Cifdaloz, Valana L. Wells, and Armando A. Rodriguez Abstract— This paper describes ...

Towards gain-scheduled H∞ control design for a tilt-wing aircraft

Decision and Control, …

Page 1. Towards Gain-Scheduled H∞ Control Design for a Tilt-Wing Aircraft David R. Mix, John S. K... more Page 1. Towards Gain-Scheduled H∞ Control Design for a Tilt-Wing Aircraft David R. Mix, John S. Koenig, Karen M. Linda, Oguzhan Cifdaloz, Valana L. Wells, and Armando A. Rodriguez Index Terms:Tilt-Wing, Rotary-Wing ...

Constrained H~~ Mixed-Sensitivity Optimization for Stable Infinite-Dimensional Plants: Application to Thermal Diffusion Process

American Control Conference, 2006

Page 1. Constrained H∞ Mixed-Sensitivity Optimization for Stable Infinite-Dimensional Plants: App... more Page 1. Constrained H∞ Mixed-Sensitivity Optimization for Stable Infinite-Dimensional Plants: Application to Thermal Diffusion Process Oguzhan Cifdaloz and Armando A. Rodriguez Abstract—This paper shows how H∞ near ...

… and Control, 2005 …, 2005

This paper examines the design of digital compensators for high frequency switching dc-dc buck co... more This paper examines the design of digital compensators for high frequency switching dc-dc buck converters. While a high sampling frequency is desirable for digital controllers to minimize intersample effects and recover the performance of the analog compensator (e.g. regulation, robustness with respect input voltage and load fluctuations), finite wordlength effects (i.e. binary approximation/truncation) become more pronounced when faster sampling rates are used. High sampling rates are also accompanied by larger power consumption. When low sampling rates are used, (appropriate truncation algorithms) permit the use of fewer bits to represent compensator coefficients. This reduces final chip area, power consumption, and cost-all very important for applicationspecific integrated circuit (ASIC) applications. This, however, comes at the expense of performance degradation because of zero-order-hold (ZOH) phase lag and intersample effects. This is a fundamental limitation associated with the traditional two-step design procedure-analog-design followed by conversion-to-digital. While one can compensate for the effects of the ZOH/intersample behavior, direct discrete-time design approach is more systematic. It must be noted, however, that even a direct discrete-time design approach has fundamental limitations. This is because such an approach does not directly take into account intersample behavior. Because of this, the direct design approach may result in unnecessarily (conservatively) high sampling rates. In view of this limitation, we propose the use of direct sampled-data design techniques which use "lifting" concepts that capture the periodic structure of the sampled data system in order to obtain a tractable optimization problem that accommodates meaningful (weighted H ∞) closed loop performance specifications as well as sample rate and intersample behavior. The design obtained is similar to the discretized classical designs complexity-wise-but operates at a much lower sampling rate. FPGA implementation data are presented for each design. Comparisons demonstrating the benefits of the sampled-data approach in achieving reasonable trade-offs are presented. Other issues addressed include: finite word length effects, controller complexity and realization. I. INTRODUCTION Motivation. The demand for smaller, reliable, high speed, efficient, low cost pulse width modulator (PWM) dc-dc power converters that are very accurate and robust to anticipated uncertainties (e.g. input voltage fluctuations, load variations, parametric uncertainty, etc.) has increased steadily as they are used in the majority of dc-dc conversion applications. Feedback compensation is essential to meet performance Oguzhan Cifdaloz, Sivaram Konasani, Murshidul Islam are currently working towards a Ph.D. in Electrical Engineering, Arizona State University.

Robust LPV H∞ gain-scheduled hover-to-cruise conversion for a tilt-wing rotorcraft in the presence of CG variations

Decision and Control, …

Page 1. Robust LPV H∞ Gain-Scheduled Hover-to-Cruise Conversion for a Tilt-Wing Rotorcraft in the... more Page 1. Robust LPV H∞ Gain-Scheduled Hover-to-Cruise Conversion for a Tilt-Wing Rotorcraft in the Presence of CG Variations Jeffrey J. Dickeson David Miles Oguzhan Cifdaloz Valana L. Wells Armando A. Rodriguez Intelligent ...

TURKISH JOURNAL OF ELECTRICAL ENGINEERING & COMPUTER SCIENCES, 2021

In this paper, a method to construct the line of sight rate of a target with a roll-pitch gimbal ... more In this paper, a method to construct the line of sight rate of a target with a roll-pitch gimbal and tracker is described. Construction of line-of-sight rate is performed via utilizing a virtual pitch-yaw gimbal. Kinematics of both the roll-pitch and pitch-yaw gimbals are described. A dynamical model for the roll-pitch gimbal is developed, and a nested control structure is designed to control the angular rates and line of sight angles. A kinematic model of the tracker is developed and a tracker controller is designed to keep the target in the field of view. Conversion equations between roll-pitch and pitch-yaw gimbal configurations are provided. Finally, constructed line of sight rates are compared to true line of sight rates via simulations. Obtained results indicate that the constructed line of sight rates pertaining to a target satisfactorily converge to the actual line of sight rates.

GAZI UNIVERSITY JOURNAL OF SCIENCE, 2021

• Control systems provides robust and implementable solutions to management of renewable resource... more • Control systems provides robust and implementable solutions to management of renewable resources. • Optimal solution to management problem is difficult to implement and vulnerable to uncertainties. • Well-established tools and methods of control systems discipline proposes alternative solutions.

Challenges and Paradigms in Applied Robust Control, 2011

A critical challenge faced by sustainability science is to develop robust strategies to cope with... more A critical challenge faced by sustainability science is to develop robust strategies to cope with highly uncertain social and ecological dynamics. The increasing intensity with which human societies utilize (limited) natural resources is fueling the global debate and urging the development of resource management methodologies/policies to effectively deal with very demanding socio-bio-economical issues. Unfortunately, despite concerted efforts by governments, many natural resources continue to be poorly managed.

AIAA Guidance, Navigation and Control Conference and Exhibit, 2008

Most of the cases of rupture of uterus occurs in the third trimester of pregnancy or during labou... more Most of the cases of rupture of uterus occurs in the third trimester of pregnancy or during labour but here we report a thirty five year old women G3, P1+1, LCB 10 years back , mode of delivery by LSCS was admitted in MG ward of Malda medical college, West Bengal, India at 16 weeks of pregnancy with complain of acute abdominal pain, vomiting with clinical sign of shock without vaginal bleeding. Haemoperitoneum and dead fetus outside the uterus was discovered by urgent USG of whole abdomen. Emergency laparotomy was carried out and it revealed haemoperitoneum due to spontaneous rupture of uterine fundus through which fetus and placenta were extruded in peritoneal cavity. Though spontaneous fundal rupture is very rare in early second trimester of pregnancy, it should be taken into consideration in the differential diagnosis of acute abdomen during pregnancy specially if there is predisposing factors.

Proceedings of the National Academy of Sciences, 2007

A critical challenge faced by sustainability science is to develop strategies to cope with highly... more A critical challenge faced by sustainability science is to develop strategies to cope with highly uncertain social and ecological dynamics. This article explores the use of the robust control framework toward this end. After briefly outlining the robust control framework, we apply it to the traditional Gordon–Schaefer fishery model to explore fundamental performance–robustness and robustness–vulnerability trade-offs in natural resource management. We find that the classic optimal control policy can be very sensitive to parametric uncertainty. By exploring a large class of alternative strategies, we show that there are no panaceas: even mild robustness properties are difficult to achieve, and increasing robustness to some parameters (e.g., biological parameters) results in decreased robustness with respect to others (e.g., economic parameters). On the basis of this example, we extract some broader themes for better management of resources under uncertainty and for sustainability scie...

Environmental Modeling & Assessment, 2010

This paper presents a framework for the study of policy implementation in highly uncertain natura... more This paper presents a framework for the study of policy implementation in highly uncertain natural resource systems in which uncertainty cannot be characterized by probability distributions. We apply the framework to parametric uncertainty in the traditional Gordon-Schaefer model of a fishery to illustrate how performance can be sacrificed (traded-off) for reduced sensitivity and hence increased robustness, with respect to model parameter uncertainty. With sufficient data, our robustness-vulnerability analysis provides tools to discuss policy options. When less data are available, it can be used to inform the early stages of a learning process. Several key insights emerge from this analysis: (1) the classic optimal control policy can be very sensitive to parametric uncertainty, (2) even mild robustness properties are difficult to achieve for the simple Gordon-Schaefer model, and (3) achieving increased robustness with respect to some parameters (e.g., biological parameters) necessarily results in increased

2009 American Control Conference, 2009

In this paper, we examine the control of a scramjet-powered hypersonic vehicle with significant a... more In this paper, we examine the control of a scramjet-powered hypersonic vehicle with significant aeroelastic-propulsion interactions. Such vehicles are characterized by open loop unstable non-minimum phase dynamics, low frequency aero-elastic modes, significant coupling, and hard constraints (e.g. control surface deflection limits, thrust margin). Within this paper, attention is placed on maintaining acceptable closed loop performance (i.e. tracking of speed and flight path angle commands) while satisfying hard control surface deflection constraints as well as stoichiometrically normalized fuel-equivalency-ratio (FER) margin constraints. Control surface constraints are a consequence of maximum permissible aerodynamic loading. FER margin constraints are a consequence of thermal choking (i.e. unity combustor exit Mach number) and the fact that thrust loss may not be captured for FER greater than unity. Such limits are particularly important since the vehicle is open loop unstable and "saturation" can result in instability. To address these issues, one can design conservative (i.e. less aggressive or lower bandwidth) controllers that maintain operation below saturation levels for anticipated reference commands (and disturbances). Doing so, however, unnecessarily sacrifices performance -particularly when small reference commands are issued. Within this paper, the above issues are addressed using generalized predictive control (GPC). A 3DOF longitudinal model for a generic hypersonic vehicle, which includes aero-elastic-propulsion interactions, is used to illustrate the ideas.

H -infinity mixed-sensitivity optimization for infinite dimensional plants subject to convex constraints

Management of Open-Access Renewable Resources with Depensation Dynamics: Control Systems Perspective

2021 8th International Conference on Electrical and Electronics Engineering (ICEEE)

Renewable resources are being over exploited at an increasing rate. Institutions/governments are ... more Renewable resources are being over exploited at an increasing rate. Institutions/governments are compelled to devise effective policies and strategies to sustainably manage renewable resources under social, ecological and environmental pressures that stem from increasing demand, model uncertainties, disturbances, and measurement errors. Open-access policies to harvest renewable resources are still widely used around the world. They are mildly regulated by implementing landing quotas, defining harvesting seasons, and/or constraining the technology used for harvesting. In many parts of the world, including the regions that are highly developed, open-access fisheries are failing. In this paper, management of an open-access renewable resource (fishery) with depensation dynamics is formulated as a control systems problem and a strategy to sustainably manage the renewable resource is proposed. First, dynamics of an unregulated open-access fishery is described and its ulnerabilities are stated. Then, an easy-to-implement regulation strategy based on classical control systems ideas is proposed and its robustness characteristics are provided. The management policy (control law) is implemented via manipulating economic variables, i.e. by adjusting the (opportunity) cost of harvesting. An agent-based model is used to model the resource exploiters (i.e. fishermen). It is shown that a classical control law can be used to effectively manage an open access fishery subject to sampling effects.

Towards gain-scheduled H∞ control design for a tilt-wing aircraft

Page 1. Towards Gain-Scheduled H∞ Control Design for a Tilt-Wing Aircraft David R. Mix, John S. K... more Page 1. Towards Gain-Scheduled H∞ Control Design for a Tilt-Wing Aircraft David R. Mix, John S. Koenig, Karen M. Linda, Oguzhan Cifdaloz, Valana L. Wells, and Armando A. Rodriguez Index Terms:Tilt-Wing, Rotary-Wing ...

Going Beyond Panaceas Special Feature: Panaceas, uncertainty, and the robust control framework in sustainability science

Pnas, 2007

Proceedings of the 44th IEEE Conference on Decision and Control, 2005

In many applications, it is essential to limit control signals. This paper presents methods that ... more In many applications, it is essential to limit control signals. This paper presents methods that process accessible system signals (e.g., plant and compensator states, reference commands) to limit control signals. In contrast to "classical techniques" which limit variables by unnecessarily reducing control system bandwidth, the proposed methods limit variables in a nonconservative manner, reducing bandwidth only when necessary. A fundamental contribution of this work is that the methods presented are applicable to linear parameter varying (LPV) and quasi-LPV plants and controllers. The methods presented rely on appropriately "scaling back" key signals. The methods are conservative in that they are applicable to "slowly varying" LPV systems. Although the methods require access to all internal closed loop system state variables, one could use an appropriately designed LPV state estimator, if necessary. The Error Governer (EG) methods are applied to an LPV missile autopilot example.

American Control Conference, 2005

This paper shows how convex optimization may be used to design near-optimal finite-dimensional co... more This paper shows how convex optimization may be used to design near-optimal finite-dimensional compensators for stable linear time invariant (LTI) infinite dimensional plants. The infinite dimensional plant is approximated by a finite dimensional transfer function matrix. The Youla parameterization is used to parameterize the set of all stabilizing LTI controllers and formulate a weighted mixed-sensitivity H∞ optimization that is convex

H^∞ mixed-sensitivity optimization for distributed parameter plants subject to convex constraints

2007 46th IEEE Conference on Decision and Control, 2007

This paper focuses on Hinfin near-optimal finite- dimensional compensator design for linear time ... more This paper focuses on Hinfin near-optimal finite- dimensional compensator design for linear time invariant (LTI) distributed parameter plants subject to convex constraints. The distributed parameter plant is first approximated by a finite dimensional approximant. For unstable plants, the coprime factors are approximated by their finite dimensional approximants. The Youla parameterization is then used to parameterize the set of all stabilizing

Robust H∞ Gain-Scheduled Conversion for a Tilt-Wing Rotorcraft

Conference on Decision and Control, 2006

This paper describes the development an analysis of robust, multi-variable H∞ control systems for... more This paper describes the development an analysis of robust, multi-variable H∞ control systems for the conversion of the high-speed autonomous rotorcraft vehicle (HARVee), an experimental tilt-wing aircraft. Tilt-wing aircraft combine the high-speed cruise capabilities of a conventional airplane with the vertical takeoff and station keeping abilities of a helicopter by rotating their wings at the fuselage. Changing between cruise and

H∞ Hover-to-Cruise Conversion for a Tilt-Wing Rotorcraft

Decision and Control, …

Page 1. H∞ Hover-to-Cruise Conversion for a Tilt-Wing Rotorcraft Jeffrey J. Dickeson, David R. Mi... more Page 1. H∞ Hover-to-Cruise Conversion for a Tilt-Wing Rotorcraft Jeffrey J. Dickeson, David R. Mix, John S. Koenig, Karen M. Linda, Oguzhan Cifdaloz, Valana L. Wells, and Armando A. Rodriguez Abstract— This paper describes ...

Towards gain-scheduled H∞ control design for a tilt-wing aircraft

Decision and Control, …

Page 1. Towards Gain-Scheduled H∞ Control Design for a Tilt-Wing Aircraft David R. Mix, John S. K... more Page 1. Towards Gain-Scheduled H∞ Control Design for a Tilt-Wing Aircraft David R. Mix, John S. Koenig, Karen M. Linda, Oguzhan Cifdaloz, Valana L. Wells, and Armando A. Rodriguez Index Terms:Tilt-Wing, Rotary-Wing ...

Constrained H~~ Mixed-Sensitivity Optimization for Stable Infinite-Dimensional Plants: Application to Thermal Diffusion Process

American Control Conference, 2006

Page 1. Constrained H∞ Mixed-Sensitivity Optimization for Stable Infinite-Dimensional Plants: App... more Page 1. Constrained H∞ Mixed-Sensitivity Optimization for Stable Infinite-Dimensional Plants: Application to Thermal Diffusion Process Oguzhan Cifdaloz and Armando A. Rodriguez Abstract—This paper shows how H∞ near ...

… and Control, 2005 …, 2005

This paper examines the design of digital compensators for high frequency switching dc-dc buck co... more This paper examines the design of digital compensators for high frequency switching dc-dc buck converters. While a high sampling frequency is desirable for digital controllers to minimize intersample effects and recover the performance of the analog compensator (e.g. regulation, robustness with respect input voltage and load fluctuations), finite wordlength effects (i.e. binary approximation/truncation) become more pronounced when faster sampling rates are used. High sampling rates are also accompanied by larger power consumption. When low sampling rates are used, (appropriate truncation algorithms) permit the use of fewer bits to represent compensator coefficients. This reduces final chip area, power consumption, and cost-all very important for applicationspecific integrated circuit (ASIC) applications. This, however, comes at the expense of performance degradation because of zero-order-hold (ZOH) phase lag and intersample effects. This is a fundamental limitation associated with the traditional two-step design procedure-analog-design followed by conversion-to-digital. While one can compensate for the effects of the ZOH/intersample behavior, direct discrete-time design approach is more systematic. It must be noted, however, that even a direct discrete-time design approach has fundamental limitations. This is because such an approach does not directly take into account intersample behavior. Because of this, the direct design approach may result in unnecessarily (conservatively) high sampling rates. In view of this limitation, we propose the use of direct sampled-data design techniques which use "lifting" concepts that capture the periodic structure of the sampled data system in order to obtain a tractable optimization problem that accommodates meaningful (weighted H ∞) closed loop performance specifications as well as sample rate and intersample behavior. The design obtained is similar to the discretized classical designs complexity-wise-but operates at a much lower sampling rate. FPGA implementation data are presented for each design. Comparisons demonstrating the benefits of the sampled-data approach in achieving reasonable trade-offs are presented. Other issues addressed include: finite word length effects, controller complexity and realization. I. INTRODUCTION Motivation. The demand for smaller, reliable, high speed, efficient, low cost pulse width modulator (PWM) dc-dc power converters that are very accurate and robust to anticipated uncertainties (e.g. input voltage fluctuations, load variations, parametric uncertainty, etc.) has increased steadily as they are used in the majority of dc-dc conversion applications. Feedback compensation is essential to meet performance Oguzhan Cifdaloz, Sivaram Konasani, Murshidul Islam are currently working towards a Ph.D. in Electrical Engineering, Arizona State University.

Robust LPV H∞ gain-scheduled hover-to-cruise conversion for a tilt-wing rotorcraft in the presence of CG variations

Decision and Control, …

Page 1. Robust LPV H∞ Gain-Scheduled Hover-to-Cruise Conversion for a Tilt-Wing Rotorcraft in the... more Page 1. Robust LPV H∞ Gain-Scheduled Hover-to-Cruise Conversion for a Tilt-Wing Rotorcraft in the Presence of CG Variations Jeffrey J. Dickeson David Miles Oguzhan Cifdaloz Valana L. Wells Armando A. Rodriguez Intelligent ...