Showing papers in "IEEE Control Systems Magazine in 2005"

Stabilization of a mini rotorcraft with four rotors

Abstract: F light control of unmanned helicopters is an area that poses interesting problems for control researchers. The classical control strategy for helicopters assumes a linear model obtained for a particular operating point. Applying modern nonlinear control theory can improve the performance of the controller and enable the tracking of aggressive trajectories, as demonstrated in [1] for a 5-ft diameter main rotor helicopter. Civil and military applications of autonomous flying vehicles have been steadily increasing over the last few years. Traffic surveillance, air pollution monitoring, area mapping, agricultural applications, and remote inspection require high maneuverability and robustness with respect to disturbances. Since rotary wing vehicles can take off and land in limited spaces and hover above targets, these vehicles have certain advantages over conventional fixed-wing aircraft for surveillance and inspection tasks. © DIGITAL VISION Experimental implementation of linear and nonlinear control laws

Bicycle dynamics and control: adapted bicycles for education and research

Abstract: In this paper, the dynamics of bicycles is analyzed from the perspective of control. Models of different complexity are presented, starting with simple ones and ending with more realistic models generated from multibody software. Models that capture essential behavior such as self-stabilization as well as models that demonstrate difficulties with rear wheel steering are considered. Experiences using bicycles in control education along with suggestions for fun and thought-provoking experiments with proven student attraction are presented. Finally, bicycles and clinical programs designed for children with disabilities are described.

Electric powered wheelchairs

Abstract: The purpose of this review is to convey the depth and breadth of the research conducted on electric-powered wheelchair (EPW) control technology as well as provide insights into future directions. We review the concepts and previous work on velocity control, traction control, suspension control, stability control, stair-climbing wheelchairs, and wheelchair navigation. The information gathered in this study is intended to promote awareness of the status of contemporary powered wheelchair control technology and increase the functional mobility of people who use EPWs.

Drug dosing control in clinical pharmacology

Abstract: In this paper, the potential applications of control technology to clinical pharmacology are discussed, specifically the control of drug dosing. The use of closed-loop control for clinical pharmacology can significantly advance the understanding of the effects of pharmacological agents and anesthetics, as well as advance the state-of-the-art in drug delivery systems. In addition to delivering sedation to critically ill patients in an acute care environment, potential applications of closed-loop control include glucose, heart rate, and blood pressure regulation.

Fusion, tokamaks, and plasma control: an introduction and tutorial

Abstract: The paper discusses the process behind fusion reaction, the magnetic confinement of plasma to sustain fusion reactions, different kinds of tokamaks used for the magnetic plasma confinement, the operation of tokamaks, and the control of tokamaks. Control of tokamaks concerns the basic functions of plasma initiation, shaping, heating, current drive, stabilization, and safe termination of charges.

Introduction to Modeling and Control of Internal Combustion Engine Systems [Book Review]

Abstract: December 2005 1066-033X/05/$20.00©2005IEEE IEEE Control Systems Magazine In this issue we bring you reviews of four books covering diverse aspects and applications of advanced control. The review by Jankovic of Guzzella and Onders’ Introduction to Modeling and Control of Internal Combustion Engine Systems discusses the numerous issues that arise in controlling modern engine systems. The next review, by Jadbabaie, provides an overview of convex optimization and its applications, the subject of a recent book by Boyd and Vandenberghe. The third review, by Sarangapani, of Neural Engineering by Eliasmith and Anderson, discusses the control engineering applications of concepts from this biologically inspired area of research. Finally, the review by Borkar of Yin and Zhang’s Discrete Markov Chains explains the intricacies of two-time-scale models.

Magnetic control of plasma current, position, and shape in Tokamaks: a survey or modeling and control approaches

Abstract: Plasma current, position and shape control systems and modeling approaches were reviewed. The literature was divided into three categories, namely plasma radial position and current control, vertical stabilization of elongated plasmas, and plasma shape control. The plasma current and radial position control problem can be easily solved using a filament plasma model - the Shafarov lumped parameter equation and two separate PID controllers. At most, a MIMO controller can be used if decoupling is desired. Stabilization of the plasma vertical motion requires new control strategies in which the control algorithm is changed on the basis of an estimate of the measurement accuracy. For controlling the shape during the plasma formation and start-up phase, controllers based on magnetic flux control are useful when control requirements are not stringent.

Virtual and remote control laboratory development

Abstract: This work describes Internet functions that include video file generation and real-time control as MWS (MATLAB Web server) features, which are useful for undergraduate courses. With these functions, using virtual processes, which in turn allow video animations of simulated processes, can enhance virtual laboratories. Furthermore, MWS allows the implementation of remote laboratories operating in batch mode. WinCom or any other suitable software can be used to implement online laboratories. These methodologies provide a straightforward approach for the developer of the teaching material, the control engineering lecturer, and a low-cost option for the student user.

Interactive teaching of constrained generalized predictive control

Abstract: In this paper, an interactive educational tool for teaching the basic concepts of constrained generalized predictive control is described. Students gain insight into the selection of design parameters and discover how controlled system performance and closed-loop stability are influenced by this selection through a user-friendly presentation of constrained and unconstrained cases.

Plasma shape control for the JET tokamak: an optimal output regulation approach

Abstract: The eXtreme Shape Controller, designed and implemented on the JET tokamak, was described. The controller regulates the plasma shape as specified in terms of plasma-wall distances and maintains this plasma shape in the presence of significant variations of critical plasma parameters, namely the poloidal beta, the internal inductance, and the plasma current. The design procedure is based on the SVD of the plant output matrix. This procedure accounts for specifications on the accuracy of the controller variables as well as the maximum allowable control effort. The new controller has been fully commissioned on the JET tokamak, is in regular operation, and is delivering the expected performance.

Advances in real-time plasma boundary reconstruction: from gaps to snakes

Abstract: The problem of plasma boundary reconstruction in relation to shape control was discussed. The different approaches to guaranteeing accuracy and robustness of plasma boundary control were presented. Deformable models provide a new formulation of the plasma boundary as a continuous contour, which facilitates more accurate estimation of global shape parameters, able to describe the plasma evolution in a realistic way. The results and analyses performed on JET and ITER support the validity of snake reconstruction methodology.

Calibrating a triaxial accelerometer-magnetometer - using robotic actuation for sensor reorientation during data collection

Abstract: A kinematic model and kinematic maneuver to calibrate a triaxial accelerometer and magnetometer was derived. The calibration was accomplished by implementing the maneuver on a six-degrees-of-freedom robotic arm. Analysis of the accuracy of the experimental results was performed by generating simulated data and formulating two least-squares optimization problems. By first calibrating the accelerometers with simulated data, the possibility of inconsistency in the estimator was evaluated. By calibrating the accelerator and the magnetometer separately, discrepancies in the data and model were checked. The simultaneous calibrations produced smaller errors for both the magnetometer and accelerometer compared to the separate calibrations.

Spacecraft maneuvers and slosh control

Abstract: Slosh is a problem in spacecrafts, which often carry considerable amounts of fuel for trajectory maneuvers and momentum dumping. As fuel is consumed, the tank becomes increasingly empty, and the remaining fuel is excited by the motion of the spacecraft. Since the reaction forces and moments caused by fuel slosh can degrade the pointing accuracy of the system, it is important to predict the effect of slosh on the spacecraft attitude control system. This paper presents the development of Sloshsat (Facility for Liquid Experimentation and Validation in Orbit) FLEVO used to study the dynamics of slosh and its impact on spacecraft attitude control. The primary objective of the Sloshat FLEVO mission is to perform a variety of maneuvers while collecting detailed measurements on the resulting slosh. For validation, the computational fluid dynamics (CFD) simulations must result in highly similar behavior. CFD predictions can then serve as a truth model for assessing the performance of simpler models for developing control algorithms.

Can HIV/AIDS be controlled? Applying control engineering concepts outside traditional fields

Abstract: Given the realization that students generally fall into a high-risk group, the University of Pretoria has launched several initiatives to promote the understanding of HIV among its student population. Recent initiatives include the development of an HIV/AIDS educational CD and the use of an HIV/AIDS model in an introductory control course to illustrate standard control systems materials. The University also initiated a project where students can get some idea on how HIV treatment strategies can be developed to contain the disease. Students benefit not only from the topical nature of the subject but also from an improved understanding of how control engineering concepts can be applied outside of traditional application fields.

Control of tokamak plasmas: introduction to a special section

Abstract: This paper provides an introduction to this issue's special section on the tokamak plasma control problems that have been identified. Since tokamak plasmas are high-order, nonlinear distributed systems with a large number of instabilities, there are many challenging control problems that must be solved before fusion power production becomes viable. As more advanced controllers are successfully brought online in working tokamaks, the benefits of sophisticated control methods are becoming widely recognized in the fusion community. This recognition and the urgent control needs of the planned multibillion dollar ITER tokamak make this an exciting time to be working on tokamak plasma control.

Pumping a swing by standing and squatting: do children pump time optimally?

Abstract: Research in biomechanics supports the idea that humans perform skilled tasks as self-optimizing machines. A rider pumping a playground swing can be modeled adequately as a second-order system. The focus of this article is the problem of time-optimal pumping of a swing, where the rider pumps the swing by alternately standing and squatting. The rider-and-swing system is modeled as a pendulum with a bob of mass attached to a fixed support by a rope of variable length. Children playing on a swing generally stand up at the lowest point and squat at the highest. Using the Pontryagin minimum principle and techniques from geometric optimal control, it is shown that this pumping strategy is time-optimal for the problem of maximizing the amplitude of oscillation of a swing.

Experiments for dynamic resource allocation, scheduling, and control: new challenges from information technology-enabled feedback control

Abstract: To help educators design laboratories that support the study of information technology-enabled distributed feedback control, several inexpensive experiments for studying the design and implementation of distributed and networked dynamic resource allocation, scheduling, and control strategies are described. In each case, an overview of the experimental apparatus and the challenges involved were presented. For three of the testbeds, the experimental results for distributed decision-making strategies were shown. The ideas for experiment redesign highlight the existence of tradeoffs among experimental apparatus design, the choice of hardware and software, and research and educational objectives.

Integrating experimentation into control courses

Abstract: The Department of Mechanical Engineering at the Technische Universiteit Eindhoven, the Netherlands, aims to provide a stimulating educational environment that emphasizes the role of hands-on experiments. To achieve this goal, the Department integrated an experimentation program with courses in the mechanical engineering bachelors curriculum, starting in the first year and gradually building in complexity through the third year. To make it possible for students to perform experiments, a new approach, which include a personal notebook, a set of 30 portable data acquisition devices, a varied set of small-scale systems, and MATLAB-based software, was introduced. This approach allow the students to plan, prepare and analyze the experiments on their own notebook computers whenever they wish. While this approach has broken through the practical barriers to large-scale experimenting, the success of further integration of student experimentation into mechanical engineering curriculum ultimately depends on the efforts and creativity of staff members.

The history of analog computing: introduction to the special section

Abstract: This special issue is one in a series of occasional issues of IEEE Control Systems Magazine dedicated to history. The present issue continues the previous contributions by focusing on the development and impact of a pivotal technology. Analog computers played a key role in enabling the simulation of control systems for several decades, leading to a better understanding of theory and better designs in practice. Here we take a closer look at analog-computer technology in its historical context. a collection of eight articles - an analog-simulation tutorial, four personal histories, and three reports of current activities - written by well-known authors in the fields of analog computing and history.

Precision control of hard disk drives

Abstract: The paper discusses the challenges and trends in the precision control of the head-positioning servomechanism of a hard disk drive. The read/write head is positioned through a voice coil motor (VCM) actuator to which the heads are attached using a thin stainless steel suspension. The servomechanism is expected to move the read/write head from one track to another in minimum time (track-seek mode) and regulate head position precisely on the center of the track during track-following mode. Near time-optimal control is widely used for the seek mode, while linear mode such as proportional-integral differential (PID) plus loop-shaping compensation is used for track following. An alternative to the servomechanism is a lightweight, secondary-stage actuator placed close to the point of control. For small step commands, the dual-stage set-up significantly performs better than a single-stage actuator in regulating the read/write head position. Maneuvers for large step commands are dominated by the VCM's response where the secondary stage provides negligible improvement.

Control engineering for computing systems - industry experience and research challenges

Abstract: Control theory has an important role to play in developing new computing systems, especially complicated software systems. Control problems that commonly occur in computing systems include regulating service levels, optimizing resources, and rejecting disturbances such as variable workloads. Developing control systems to address these problems involves a number of challenges. The article describes some of the challenges that arise in applying control theory to computing systems.

Workshop on control of micro- and nano-scale systems

Abstract: M icro-and nanoscale systems are those with device features ranging in size from hundreds of microns (∼ 10 −4 µm) down to nanometers (∼ 10 −9 µm), a size that corresponds to six times the distance between the nuclei of two bonded carbon atoms. These systems enable such applications as biomedical sensors, lab-on-a-chip biochemical analysis systems, single molecule sensors and manipulators, microscale inertial systems, implantable drug delivery devices, telecommuni-cation optical fiber components, and miniaturized energy sources like fuel cells and microengines. Since 1989, the year the term microelectromechanical systems (MEMS) was coined, the field of microsystems has grown significantly. By 1997, 80 U.S. companies were involved in the field of MEMS, the combined MEMS world market had reached approximately US$2 billion, and the filing rate for MEMS patents was about 160 per calendar year [1]. The younger field of nanotechnology is also growing. More then 2,800 nanotechnology patents have been issued since 1996 [2], and government and private spending on nanotechnology research and development reached US$8.6 billion per year in 2004 [3]. There are opportunities for control theory and practice to contribute to the development of micro-and nanoscale systems. The reverse is also true: miniaturized sensors and actuators will enable new applications in distributed control and sensing. Commonalities between control and micro-/nanoscale systems are discussed below. By integrating components with micrometer and nanometer dimensions, it is possible to pack functionality into mesoscopic (less than 10 −3 m × 10 −3 m × 10 −3 m) or microscopic (less than 10 −6 m × 10 −6 m × 10 −6 m) volumes. Alternatively, miniature sensors and actuators can be dispersed over large volumes to perform distributed sensing and actuation tasks. Micro-and nanoscale technology can provide control practitioners with miniatur-ized sensors and actuators. Conversely, research developments in distributed control and sensing can be used to help integrate systems and networks of miniatur-ized devices. Micro/nanosystems exhibit chemical, electrical, mechanical, fluidic, and biological phenomena over a range of length and time scales. The range of length scales is influenced in two basic ways. First, surface-to-volume ratios are large and, thus, surface effects with nanometer length scales compete with bulk effects with length scales up to microns or millimeters. Furthermore, micro-and nanoscale systems must be integrated with human interfaces that have centimeter length scales. For nanometer systems, this integration means that system length scales can vary over seven orders of magnitude, namely, from 10 −9 …

Laboratories and real-time computing: integrating experiments into control courses

Abstract: The paper describes the approach used at the Department of Automatic Control at Lund Institute of Technology to maintain a high level of practical laboratory experiments. The Department integrates laboratory experiments into its control courses. If the laboratory exercises are properly organized and the student volume is sufficiently large, it is possible to combine a high level of practical laboratory experiments in control education at a reasonable cost. The use of off-the-shelf hardware and open-source software are important, With desktop processes, it is possible to achieve high utilization of lab space and high student throughput.

A student control competition through a remote robotics lab

Abstract: The Automatic Control Telelab (ACT) laboratory at the University of Siena, Italy, has developed a new module called the student competition system In the ACT module, students or groups of students compete to develop the best controller for a given remote process The competition not only stimulates students' interest in control systems but also enhances learning by facilitating the understanding of practical control design issues

An undergraduate laboratory for networked digital control systems

Abstract: This work describes a senior-level laboratory/project course at the University of Maryland, College Park (USA), titled "networked and distributed control systems." The course is partially supported by an NSF research and curriculum development grant and brings together undergraduates from three engineering departments (electrical and computer, mechanical, and aerospace) with plans to include chemical, civil, and fire protection engineering. The course combines digital control with networks and information technology. The course goals are to introduce students to emerging areas in systems theory, including topics in networked and distributed control systems; to leverage instructor time and increase productivity in laboratory classes while keeping student teams small; and to minimize costs by using highly adaptable general-purpose equipment.

Design and implementation of computer control software: a low cost laboratory setup

Abstract: Control systems are one of the main application domains for embedded computing. With the complexity of applications growing rapidly, it is important that engineers who design control systems be knowledgeable about the design procedures and challenges in embedded computing technology. To meet this need, a low cost laboratory setup for integrating diverse concepts is presented, including microprocessors, control systems, programming and software development, and electronics. A project based laboratory setup allows students to develop fundamental skills in the design and implementation of embedded computer controlled systems.

Switching in Systems and Control [Book Review]

Abstract: Louvain, Belgium, in 1977 and the Ph.D. degree in mechanical engineering from Columbia University, New York, in 1981. In 1983, he joined the Aerospace Engineering Department of the University of Michigan, where he is currently a professor, with a joint appointment in the Department of Electrical Engineering and Computer Science. His research and teaching interests are in the areas of dynamic systems, control, guidance, and navigation. He is a Fellow of the IEEE.

Artificial arms evolve from robots, or vice versa?

Abstract: There is a close relationship between robotics and prosthetic devices (artificial limbs) since both provide human like motion and prehension. In general, prosthetic devices have benefited from the development of robotic technologies. Interestingly, researchers at the Center for Engineering Design at the University of Utah developed the Utah Arm, a three-degree-of-freedom elbow prosthesis, prior to developing the Utah/MIT dextrous hand, a robotics end-effector. These research projects spawned two new companies, the Motion Control, Inc., the manufacturer of the Utah Arm, and Sarcos, Inc., a robotics company under the leadership of Stephen C. Jacobsen.