bluuebunny/crossref_metadata_2025 huggingface dataset:
Weighted Minimum Variance Control of Servo-Damper System With Input Energy Constraint
Authors: Kang Min-Sig , Lee Chong-Won
Published: July 2009

The weighted minimum variance control is extended to include the rational transfer function as well as the polynomial as the weighting on system input energy so as to guarantee the closed-loop stability in the whole range of the scalar input cost and the monotonic property of the controlled output and control input variances with respect to the scalar input cost. In addition, the Robbins-Monro scheme is modified for on-line adaptation of the scalar input cost under the time varying external disturbance to satisfy the constraint on input variance. The two schemes are then combined and applied to the vibration control of a servo-damper beam system. The experimental and simulation results show that the maximum usage of the available input energy is ensured in the presence of time varying external disturbance so as to achieve the good control performance and the effectiveness of the servo-damper system used for the suppression of the beam vibration.
Dynamics of Large Constrained Flexible Structures
Authors: Amirouche F. M. L. , Huston R. L.
Published: July 2009

This paper presents an automated procedure useful in the study of large constrained flexible structures, undergoing large specified motions. The structure is looked upon as a “partially open tree” system, containing closed loops in some of the branches. The governing equations are developed using Kane’s equations as formulated by Huston et al. The accommodation of the constraint equations is based on the use of orthogonal complement arrays. The flexibility and oscillations of the bodies is modelled using finite segment modelling, structure analysis, and scaling techniques. The procedures developed are expected to be useful in applications including robotics, space structures, and biosystems.
Parametrically Excited Behavior of a Railway Wheelset
Authors: Lieh J. , Haque I.
Published: July 2009

The dynamic response of rail vehicles is affected by parameters such as wheel-rail geometry, track gage, and axle load. Variations in these parameters, as a rail vehicle moves down the track, can cause instabilities that are related to parametrically excited behavior. This paper reports on the use of Floquet Theory to predict the stability and instability regions for a single wheelset subjected to harmonic variations in wheel-rail geometry, track gage and axle load. Time studies showing the response of a wheelset to various initial conditions are also included. The results show that harmonic variations in the wheel-rail geometry can influence the behavior of a wheelset significantly. The system is especially susceptible to variations in conicity. Time history studies show that the response is dependent on initial conditions, the amount of variations and the magnitude of the excitation frequency.
Optimal Control of Stochastic Parametrically and Externally Excited Nonlinear Control Systems
Authors: Young G. E. , Chang R. J.
Published: July 2009

A sub-optimal nonlinear controller which is synthesized by using the external linearization approach is applied to the optimal control of stochastic parametrically and externally excited nonlinear systems with complete state information. Algebraic necessary conditions are derived for the minimization of the quadratic cost function through the concepts of equivalent external excitation. The concepts and applications of the statistical linearization approach for the externally excited nonlinear systems are extended to the nonlinear systems subjected to both stochastic parametric and external excitations. Two examples which include a first-order nonlinear and a second-order Duffing type stochastic system are used to illustrate the performance of the present design. The applications of the statistical linearization approach to the optimal control of a stochastic parametrically and externally excited Duffing type system is illustrated and compared with the present approach by using Monte Carlo simulation.
A Statistical Methodology of Designing Controllers for Minimum Sensitivity of Parameter Variations
Authors: Tsai Kenneth C. Q. , Auslander David M.
Published: July 2009

A statistical methodology is presented for designing controllers in problems where analytical solutions are unobtainable. The methodology is applicable to many complicated systems containing, for example, nonlinearities, uncertainty, and multiple inputs and multiple outputs. Because the design technique is a simulation based approach, no specific restrictions are placed on either the plant or the controller structure. A Monte Carlo technique is used to map the parameter space onto the indices of performance. The system performance either passes or fails the performance index. The objective in systems with uncertain parameters is to select (controller) parameter values which maximize the probability of passing the performance criterion. In deterministic systems, the goal is to find parameter values in the pass region that are as insensitive as possible, that is, parameter values that allow for the maximum amount of parameter variation without causing the system response to leave the pass region.
A Hydraulic Rotary Switched-Inertance Servo-Transformer
Authors: Brown F. T. , Tentarelli S. C. , Ramachandran S.
Published: July 2009

Switched-reactance hydraulics represents a radically novel approach to the control of fluid power, since the proportional metering of flow through adjustable orifices is eliminated, and the inertive properties of the fluid substituted. Potential advantages in bandwidth, linearity, and efficiency have been indicated. This paper presents the first steady-state theory and experiments with a rotary fluid switch, which accomplishes the needed pulse-width modulation at a desirably high frequency. Cavitation problems are observed, means of their partial solution are implemented, and means of a more complete solution are indicated.
Structural Choices of 2 Versus 1 Pursuit-Evasion Differential Games
Authors: Bugnon F. J. , Mohler R. R.
Published: July 2009

Problems particular to N versus 1 differential games are investigated based on a 2 versus 1 game. A differential game arises between two sonar (or radar) systems and a target. The target uses a mixed strategy by adding white noise into its controller to hamper the tracking of the sonars. The two structures studied, a centralized and a decentralized structure that correspond to a 1 versus 1 or a 2 versus 1 game formulation, are shown to yield different results. Nash-optimality of each structure is shown to depend on the dynamics of the evader. The study provides insight into the solution of difficult problems specific to N versus 1 games. To illustrate further N versus 1 game problems, a nonoptimal scalar case is presented in which the decentralized structure is proven superior. In the same context, this stochastic problem also yields a matrix game, a bimatrix game, and a hierarchical (Stackelberg) game.
Physical Modeling With Eulerian Frames and Bond Graphs
Authors: Beaman J. J. , Breedveld P. C.
Published: July 2009

In this paper it is shown that open systems, in which matter can enter and leave, are not incompatible with bond graph topology, as commonly reported. Effective modeling of these systems requires that attention be paid to the convective coupling between systems and environment which exchange matter. The convection models proposed in this work do not require the use of active bonds (other than modulation signals), controlled sources, ad hoc elements, or any other special bond graph artifacts.
A Robust Discrete Time Adaptive Servo
Authors: Sadegh Nader , Horowitz Robert O.
Published: July 2009

This paper deals with the robustness issues associated with the design of an adaptive control servo in the presence of linear unmodeled plant dynamics. In particular, a design methodology for trajectory following control systems is presented which guarantees the boundness of the tracking error without requiring persistent excitation of the reference input. The tracking error bound is calculated as a function of the reference trajectory, using a-priori knowledge of the step response of the plant. An application of this technique to a positioning servo with an unknown or slowly varying inertia load and high frequency unmodeled resonance modes is included.
Pointwise-Optimal Control of Robotic Manipulators
Authors: Tadikonda S. , Baruh H.
Published: July 2009

A method is presented for the pointwise-optimal control of robotic manipulators along a desired trajectory. An approximate expression for the manipulator response is used to minimize a quadratic performance index with a linear regulator and tracking criterion, during each sampling period. The delay associated with implementation of the control action is analyzed, and its adverse effects are eliminated by estimation of the joint angles and torques one time step ahead.
The Kinematic Inversion of Robot Manipulators in the Presence of Singularities
Authors: Angeles J. , Anderson K. , Cyril X. , Chen B.
Published: July 2009

Presented in this paper is an algorithm that allows the numerical kinematic inversion of robot manipulators in the presence of singularities. It is aimed at continuous-path applications, in which known algorithms produce branch switching and hence jump discontinuities in the joint rates. In the algorithm proposed here the joint rates are computed at singularities as the solution of a quadratic-programming problem that eliminates branch switching. Joint accelerations are computed likewise, and joint angles by Taylor expansion using up to quadratic terms.
A New Algorithm for Limit Cycle Analysis of Nonlinear Control Systems
Authors: Pillai V. K. , Nelson H. D.
Published: July 2009

A numerical method is presented for the limit cycle analysis of multiloop nonlinear control systems with multiple nonlinearities. Describing functions are used to model the first harmonic gains of the nonlinearities. Existence of a limit cycle is sought by driving the least damped eigenvalues to the imaginary axis. The evolution of the limit cycle is studied next as a function of a critical system-parameter. It is shown that by defining a suitable error function it is possible to use both eigenvalue as well as the eigenvector sensitivities to formulate a generalized Newton-Raphson method to solve simultaneously for the updates of state variable amplitudes in a minimum norm sense. Several case studies have been presented and the development of a numerical procedure to test the stability of the limit cycle has also been reported.
Bond Graph Modeling of Continuous Solids in Finite Strain Elastic-Plastic Deformation
Authors: Fahrenthold E. P. , Wu A.
Published: July 2009

The physical systems modeling theory of bond graphs may be employed to represent the hysteretic deformation of continuous solids infinite strain elastic-plastic deformation. Second and fourth order tensors represent stress power conjugate variables and transformer or gyrator moduli, respectively, with corresponding inner products generalizing the power flow and modulation calculations of scalar and vector bond graphs. Capacitors and resistors of a tensor type suitably represent strain energy storage, associated flow rules in plasticity, and other familiar concepts. An important application of this simulation technique arises in constitutive modeling studies of nonlinear materials.
An Approach Toward the Optimal Semi-Active Suspension
Authors: Hrovat D. , Margolis D. L. , Hubbard M.
Published: July 2009

In this paper, a two-degree-of-freedom model of a semi-actively suspended vehicle is used as a starting point in the design of an optimal suspension. The optimization is performed with respect to a quadratic performance index reflecting suspension design constraints and ride quality requirements. Two closely related mathematical descriptions of the model are given, one leading to a linear and the other to a bilinear system of differential equations, with an additional inequality constraint reflecting the passivity of the semi-active device. Since the resulting stochastic optimization problem does not allow for a closed-form analytical solution, a numerical method is proposed as an approximate solution. The justification for the method is based on a recent existence theorem from stochastic optimal control theory. Illustrative simulation results of the optimization are presented.
Frequency Domain Stability Criterion for Vibration Control of the Bernoulli-Euler Beam
Authors: Chait Yossi , Radcliffe Clark J. , MacCluer C. R.
Published: July 2009

A new single-input single-output frequency domain stability criterion for distributed parameter systems is illustrated by application to feedback control of a Bernoulli-Euler beam. The system is modeled using an infinite partial fraction expansion, while the control design is based on a truncated model. The Nyquist plot is shown to lie within a “tube of uncertainty” of the plot for the truncated model. Several numerical examples illustrate the power and simplicity of this criterion.
Modeling and Simulation of a Supercharger
Authors: Merala Raymond , Hubbard Mont , Miyano Takashi
Published: July 2009

A dynamic model is developed for simulating and predicting performance for superchargers of relatively arbitrary geometric configuration. A thermodynamic control volume approach and bond graph models are used to derive continuity and energy equations linking the various control volumes. Bond graphs also serve to study and understand the causal implications of laws governing flows between control volumes and system dynamics. Heat transfer is neglected. Simulation outputs include time histories of pressure, temperature, mass, and energy associated with each control volume, time histories of the various flows in the supercharger, and overall volumetric efficiency. Volumetric efficiencies are predicted over a wide range of speed/pressure ratio combinations and are within three percent of experimentally measured values. The simulation is used to investigate the sensitivity of supercharger performance to several key design parameters, including rotor-rotor separation, and rotor-housing and side plate clearance distances.
Analysis and PID Controller Design of PWM Systems
Authors: Wu Shing-Gwo , Chen Wen-Liang
Published: July 2009

This paper consists of two parts. The first part derives a procedure to analyze a pulse-width-modulated control system via block-pulse functions. The second part gives the procedure to design the PID controller for the PWM system.
Integrated Communication and Control Systems: Part I—Analysis
Authors: Halevi Yoram , Ray Asok
Published: July 2009

Computer networking is a reliable and efficient means for communications between disparate and distributed components in complex dynamical processes like advanced aircraft, spacecraft, and autonomous manufacturing plants. The role of Integrated Communication and Control Systems (ICCS) is to coordinate and perform interrelated functions, ranging from real-time multi-loop control to information display and routine maintenance support. In ICCS, a feedback control loop is closed via the common communication channel which multiplexes digital data from the sensor to the controller and from the controller to the actuator along with the data traffic from other loops and management functions. Due to the asynchronous time-division multiplexing of the network protocol, time-varying and possibly stochastic delays are introduced in the control system, which degrade the system dynamic performance and are a source of potential instability. The paper is divided into two parts. In the first part, the delayed control system is represented by a finite-dimensional, time-varying, discrete-time model which is less complex than the existing continuous-time models for time-varying delays; this approach allows for simpler schemes for analysis and simulation of ICCS. The second part of the paper addresses ICCS design considerations and presents simulation results for certain operational scenarios of ICCS.
Verification of a Dynamic Grinding Model
Authors: Kurfess T. R. , Whitney D. E. , Brown M. L.
Published: July 2009

Many applications of industrial robot automation can be made possible or improved with the introduction of a force feedback system. The task of weld bead removal is being studied in an effort to develop a real time force controlled intelligent system. The process of weld bead grinding must be analyzed and modelled to develop a weld bead removal system. Previous research has developed and verified static models of grinding. This paper describes a dynamic model developed from the grinding characteristics demonstrated previously. An experimental grinding system was built and the measured process behavior was compared with a grinding simulation based on the dynamic model. The profile of the specimen was measured prior to and subsequent to grinding. The initial profile was used as an input to the simulation, and the output from the simulation was compared with the final measured profile. A variety of conditions was tested. For typical mean cut depths of 0.10 mm the simulator predicted the final height of the grinding specimen within a standard deviation of 0.02 mm. The dynamic model was verified within 10 percent of the actual results.
Modeling and Implementation of Semi-Active Hydraulic Engine Mounts
Authors: Graf P. L. , Shoureshi R.
Published: July 2009

In an effort to improve passenger comfort, the automotive industry is evaluating more sophisticated techniques to reduce engine excited frame vibrations. A new approach is to implement hydraulic mounts in a semi-active mode. In this mode, low power actuators are used to change the impedance characteristics of the mount. This paper presents a dynamic model and analysis of the semi-active hydraulic mount. Experimental data confirming the mount model are presented. Finally, results of an experimental study on the implementation of the semi-active mounts on a production automotive vehicle are presented. The study focuses on frame vibration reduction during engine idle. The semi-active hydraulic mounts show improved vibration levels over passive hydraulic mounts in the vehicle application.
A Dynamic Optimization for Operation of a Compressed Air Energy Storage System
Authors: Weiner Dan
Published: July 2009

A mathematical model is derived, simulating the dynamic behavior of a cavern-type (constant volume) compressed air energy storage system (CAES). With the aid of the model, optimal control of the system decision variables, namely: charging and discharging timing and duration as well as the fuel injection policy are determined by periodic dynamic programming method. The performance criterion is maximizing the net benefits over the operation cycle. An algorithm for numerical solution of the problem is presented and computational results for an example representing a real plant are given.
An Approach to Adaptive Control of Robot Manipulators Using the Computed Torque Technique
Authors: Goldenberg A. A. , Apkarian J. A. , Smith H. W.
Published: July 2009

Manipulator’s control system based on computed torque techniques incorporates a model of the manipulator dynamics. The nominal torque, computed using this mathematical model, does not reflect the effects of unknown loadings and uncertainty in modelling the parameters. An approach is presented which compensates for unknown loading and parameter uncertainty. This compensation is based on the “recursive” identification of a new dynamics operator which maps a vector of generalized coordinates into the vector of generalized forces (joint torques). The identification is based on a least-square approximation. Using the identified operator, which provides the compensated nominal torque, the system is controlled in closed-loop to generate regulation of the error in joint coordinates. The regulation is obtained using a common discrete optimization feedback law which is based on a recursive identification of the first order approximation of the dynamics model. The approach is illustrated with simulation results.
Nonlinear Robust Industrial Robot Control
Authors: Kuo C. Y. , Wang Shay-Ping T.
Published: July 2009

A new nonlinear robot control scheme is proposed in this paper which is robust against modeling errors and unknown disturbance. The control input consists of a nonlinear part and a linear part. The nonlinear part decouples robot dynamics to obtain a set of equations in terms of each joint’s input and output; the linear part applies robust servomechanism theory to suppress effects of modeling error and unknown disturbance. The nonlinear part can be calculated by using recursive Newton-Euler formulas or parallel processing hardware, and the linear part by dedicated, localized microprocessors. Therefore, this methodology is computationally efficient, and is applicable to general robot configuration. The scheme is applied to control a two-joint, SCARA-type robot. The simulation results demonstrate that this scheme can achieve fast and precise robot motion control under substantial modeling errors.
Automatic 6-D.O.F. Kinematic Trajectory Acquisition and Analysis
Authors: Antonsson E. K. , Mann R. W.
Published: July 2009

An optoelectronic photogrammetric system to measure the spatial kinematic histories of linkages is presented. A Body Coordinate System approach produces both three-dimensional position and orientation trajectories with no singularities for any rotation. Bandwidth is in excess of 300 Hz for each of 10 link elements. A detailed analysis and measurement of the intrinsic camera calibration corrections has been performed using 12,000 calibration points per camera. An independent verification of spatial accuracy has been performed.
A Model for In-Process Control of Thermal Properties During Welding
Authors: Doumanidis C. C. , Hardt D. E.
Published: July 2009

The control of welding processes has received much attention in the past decade, with most attention placed on real-time tracking of weld seams. The actual process control has been investigated primarily in the context of weld bead geometry regulation, ignoring for the most part the metallurgical properties of the weld. This paper addresses the latter problem through development of a model for in-process control of thermally activated material properties of weld. In particular, a causal model relating accessible inputs to the outputs of weld bead area, heat affected zone width, and centerline cooling rate at a critical temperature is developed. Since the thermal system is a distributed parameter, nonlinear one, it is modelled numerically to provide a baseline of simulation information. Experiments are performed that measure the thermal response of actual weldments and are used to calibrate the simulation and then to verify the basic dynamics predicted. Simulation results are then used to derive a locally linear transfer function matrix relating inputs and outputs. These are shown to be nonstationary, depending strongly upon the operating point and the boundary conditions.
A Novel Output Feedback Pusher Plate Controller for the Penn State Electric Ventricular Assist Device
Authors: Tsach U. , Geselowitz D. B. , Sinha A. , Hsu H. K.
Published: July 2009

This paper addresses the development of an output feedback controller for the Penn State Electric Ventricular Assist Device (EVAD). The control law is designed to minimize the electric power consumption of the motor, while utilizing the measured pusher plate position as its only feedback signal. The control algorithm results in a suboptimal performance. The feedback gain function is calculated such that the expected value of the deviations between the suboptimal and full state feedback power consumption values is minimized. The system state initial conditions are treated as random variables with specified probability density functions. Numerical simulations indicate that the output feedback controller of the EVAD has a near optimum performance (the excessive electric power consumption is less than 1 percent), and a time shift manipulation of a single feedback gain function can drive the EVAD in various speeds with minimal energy losses.
A Rotary Magnetic Damper or Brake Consisting of a Number of Sector Magnets and a Circular Conductor
Authors: Nagaya Kosuke , Karube Yasuo
Published: July 2009

This paper is concerned with a method for analyzing a rotary magnetic damper (eddy current brake) consisting of a number of sector magnets and a circular conductor. The analytical solution to obtain an eddy current, a braking force, and a damping coefficient is obtained by dividing the magnetic flux into the narrow sectors. Numerical calculations have been carried out for the variation of the flux range, the position, and the number of the magnets. Experimental tests are also carried out to verify the present theoretical results. The theoretical results are in good agreement wtih the experimental ones.
Steady-State Optimal State and Input Observer for Discrete Stochastic Systems
Authors: Park Y. , Stein J. L.
Published: July 2009

Model-based machine diagnostics techniques require the modeled states and machine inputs to be measured. Because measurement of all the states and inputs is not always possible or practical, a simultaneous state and input observer is required. Previous work has developed this type of acausal observer and shown it is susceptible to noise. This paper develops a steady-state optimal observer that minimizes the trace of the steady-state error covariance of the state and input estimates for discrete, linear, time-invariant, stochastic systems with unknown inputs. In addition, a method to distinguish the best measurement set among the available measurement sets is developed. Results from numerical simulations show that the optimal observer can greatly improve estimation results in some cases.
Comparison of a Fuzzy Logic Controller With a P + D Control Law
Authors: Daley S. , Gill K. F.
Published: July 2009

A study is described that compares the performance of a self-organizing fuzzy logic control law (SOC) with that of the more traditional P + D algorithm. The multivariate problem used for the investigation is the attitude control of a flexible satellite that has significant dynamic coupling of the axes. It is demonstrated that the SOC can provide good control, requires limited process knowledge and compares favorably with the P + D algorithm.
Shape-Reconstruction System for Three-Dimensional Objects Using an Ultrasonic Distance Sensor Mounted on a Manipulator
Authors: Tsujimura Takeshi , Yabuta Tetsuro , Morimitsu Takenori
Published: July 2009

This paper presents a three-dimensional shape-reconstruction system that employs an ultrasonic distance sensor placed on a manipulator. This system can not only reconstruct the shape of an object, but it can also precisely assess the distance from the manipulator to the object. By employing the freedom of the manipulator, the system can measure an object with the sensor in any position and orientation, and can then numerically reconstruct object images using measured data. Experimental results show that the newly developed system and method make object shape reconstruction easy and inexpensive. They also show that the three-dimensional object data obtained by this method can be used in manipulator control.
Time Optimal Control of Balanced Manipulators
Authors: Newman W. S. , Hogan N.
Published: July 2009

An efficient algorithm is presented for solving time-optimal control for a restricted class of manipulators: balanced, decoupled manipulators. It is shown how the dynamics of such manipulators are sufficiently simple that optimal control solutions for point-to-point moves can be found analytically. A change of coordinates is proposed in which the more difficult problem of time-optimal interception of moving targets can be solved efficiently. A fast algorithm is described for computing and updating optimal interception solutions on line.
Kinematics of a Hybrid Series-Parallel Manipulation System
Authors: Waldron K. J. , Raghavan M. , Roth B.
Published: July 2009

In this paper we first derive the coordinate transformations associated with a three-degree-of-freedom in-parallel-actuated micro-manipulator. Then we combine these results with the transformations associated with an in-series three-axis wrist on which the in-parallel micro-manipulator is mounted. The results are the basic transformation equations between joint-space position variables and end-effector (or task space) position variables for a hybrid series/parallel six-degree-of-freedom manipulator system. This structural combination results in a manipulator which exhibits desirable fine and gross motion characteristics as both a stand-alone device or as a sub-system of a more complex system with redundant degrees of freedom. The forward and inverse position kinematics and rate and force decomposition for this hybrid six-degree-of-freedom linkage are presented.
Optimal Load Distribution for Two Industrial Robots Handling a Single Object
Authors: Zheng Y. F. , Luh J. Y. S.
Published: July 2009

The load distribution problem for two coordinating industrial robots handling a single object is studied in this paper. When two industrial robots grasp a single object, the total number of applied torques is usually greater than six. Thus the joint torques of two robots for a required motion of the object is not unique. The redundant degrees of freedom may be used to optimize certain kind of performance. We first select the least energy consumption as the optimization criterion. Optimal algorithms without and with a bound on the joint torques are investigated. The results show that the algorithms are computationally complicated which are not suitable for real-time applications. Alternatively, optimal algorithms are then proposed for load distribution with minimum exerted forces on the object. The algorithms are obtained with much less computational time, which makes it attractive for real-time applications. The algorithms are applied to two PUMA 560 type robots as an illustration.
Experimental Implementation of a Deterministic Controller for a D.C. Motor With Uncertain Dynamics
Authors: Horowitz R. , Stephens H. I. , Leitmann G.
Published: July 2009

The control of d.c. motors is often complicated by the fact that the dynamics of the system to be controlled are unknown. In this paper a deterministic controller is employed to control a d.c. motor which experiences a varying inertia load, Coriolis forces and unknown friction disturbances. All of the uncertainties in the system are assumed to be bounded. A hybrid controller, using a continuous velocity loop and a digital position loop, is developed. Experimental results verify the controller efficacy in dealing with bounded deterministic uncertainties.
Stability Analysis of a Nonlinear Wheelset Rolling on Rough Track
Authors: Castelazo I. A. , Hedrick J. K.
Published: July 2009

The lateral stability of a nonlinear rail vehicle wheelset subject to random track irregularities is analyzed by the random plus sinusoid describing function method. The nonlinearities considered are wheel/rail profile geometry and friction force saturation. A state space, dual-input, equivalent linearization procedure is developed and applied to the wheelset model. It is shown that on perfectly smooth track creep force saturation increases the critical speed and limits the maximum lateral amplitude. The nonlinear geometry creates several stability boundaries (stable and unstable) and limits the maximum wheelset excursion to lower values than the creep force saturation does. This method predicts the experimentally observed phenomenon of intermittent hunting, i.e., a two-mode response randomly shifting between a limit cycling and a nonlimit cycling behavior, when running on rough track near the critical speed. The predicted response is compared to the results from digital simulations and is shown to be quite accurate.
Design of an Electrohydraulic Positioning System Using a Novel Model Reference Control Scheme
Authors: Hori N. , Pannala A. S. , Ukrainetz P. R. , Nikiforuk P. N.
Published: July 2009

A new model reference control method is presented for a linear, time-invariant system which may have multiple inputs and outputs. The design method is described in the discrete-time form using the Euler operator, which approaches the Laplace operator as the sampling interval aproaches zero. This method is applied to the positioning control of an electrohydraulic servo actuator and implemented using a personal computer in real time. The experimental results show that the plant response is significantly improved using the proposed method over the conventional output feedback method. The proposed method has potential applications to robots and other servomechanisms.
Controller Design for a Multichannel Electrohydraulic System
Authors: Pannala A. S. , Dransfield P. , Palaniswami M. , Anderson J. H.
Published: July 2009

In multi-actuator powered control applications, load coupling can cause severe interactions between the actuators. It is possible to reduce such interactions by incorporating suitable controller actions. The paper concerns a two-actuator electrohydraulic force-control system. A computer-aided procedure involving multi-variable frequency response techniques to help design controller action is presented. Experimental evidence which confirms the effectiveness of simple controllers arrived at by this approach is presented.
Application of a New Pressure Intensifier Using Oil Hammer to Pressure Control of a Hydraulic Cylinder
Authors: Suzuki K.
Published: July 2009

In a previous paper the author proposed to actively utilize the pressure rise phenomenon of an oil hammer and a new type of a hydraulic pressure intensifier using oil hammers. In this paper, one application of this intensifier is tested, where the intensifier is connected to a hydraulic cylinder. The hydraulic cylinder is driven by pressure which is several times higher than the original pump pressure. In addition, a method to use this system as a pressure control device is proposed and its principle and performance is clarified.
Robust Simplified Adaptive Stabilization of Not Necessarily Minimum-Phase Plants
Authors: Bar-Kana Izhak
Published: July 2009

Recently it was shown that first-order adaptive regulators can stabilize any linear time-invariant plant whose transfer function has arbitrary relative degree and order and is not necessarily minimum phase, provided that the dominant slow part of the plant is minimum phase and of relative degree one and the parasitic fast part is stable. Both the algorithm and the problem formulated are particular cases of the general model following problem in multivariate plants that can be stabilized via static or dynamic output feedback. This paper gives a unified presentation and a brief intuitive motivation for the different adaptive procedures that together lead to simplified robust adaptive controllers.
Prediction of Stationary Response of Robot Manipulators Under Stochastic Base and External Excitations—Statistical Linearization Approach
Authors: Chang R. J. , Young G. E.
Published: July 2009

The Lagrangian dynamic equation and statistical linearization for an n-dimensional manipulator subjected to both stochastic base and external excitations and geometric constraints in states are derived. The effects of utilizing a truncated Gaussian density in the linearization due to the geometry constraints are justified. The non-Gaussian effects due to the stochastic base excitation are also quantified to justify the accuracy in the prediction of the stationary output variances. Two examples of robot manipulators are selected to illustrate the accuracy of predicted variances by the linearization techniques.
An Efficient Algorithm for Shortest Path in Three Dimensions With Polyhedral Obstacles
Authors: Khouri J. , Stelson K. A.
Published: July 2009

An algorithm to find the shortest path between two specified points in three-dimensional space in the presence of polyhedral obstacles is described. The proposed method iterates for the precise location of the minimum length path on a given sequence of edges on the obstacles. The iteration procedure requires solving a tri-diagonal matrix at each step. Both the computer storage and the number of computations are proportional to n, the number of edges in the sequence. The algorithm is stable and converges for the general case of any set of lines, intersecting, parallel or skew.
Steady Turning Stability of Partially Filled Tank Vehicles With Arbitrary Tank Geometry
Authors: Ranganathan R. , Rakheja S. , Sankar S.
Published: July 2009

Steady turning model of a partially filled tank vehicle is developed by integrating the roll plane model of the partially filled arbitrarily shaped tank with the static roll plane model of an articulated vehicle. The rollover immunity of the tank vehicle is investigated through computer simulation. The motion of the free surface of liquid and the associated load shift encountered during steady turning are computed using an iterative algorithm. The influence of tank geometry and liquid fill level on the rollover immunity of the tank vehicles is presented. Rollover threshold levels of a tractor-semitrailer vehicle with tanks of circular, modified square and modified oval cross sections are investigated for various fill levels. The influence of compartmenting of the tank on the steady turning response of the vehicle is presented and an optimal order of unloading the various compartments is determined. The study concludes that load shift encountered during steady turning has an adverse effect on the overturning limits of the articulated liquid tank vehicles. The stability of such tank vehicles may be further affected by the dynamic fluid-structure interactions, vehicle transients and driver’s reaction.
Interaction of Web Spans: Part II—Dynamics
Authors: Young G. E. , Shelton J. J. , Fang B.
Published: July 2009

The dynamic equations for web span interaction are derived. Due to the three different possible interaction modes the analysis relies heavily on the static analysis presented in Part I. A Fourier analysis has also been included. The frequency analysis reveals that if both web spans are in the underdamped mode, large oscillations will occur in some range of steering frequencies. Experimental verification is presented for both the static and dynamic analyses.
Optimal Control of Thermal Power Plants
Authors: Nakamura H. , Toyota Y. , Kushihashi M. , Uchida M.
Published: July 2009

Application of optimal control system to thermal power plants is introduced. The suggested system consists of the conventional PID controllers and the control computer. It has been successfully applied to five supercritical power plants in Kyushu Electric Power Company (Total output 2,700 MW) since 1978. In the system, system identification or state space representation of the plant is performed based on the AR (Autoregressive) model describing the system dynamics. The optimal controller is designed by the orthodox Dynamic Programming procedure under a quadratic criterion function. In the paper, the procedure of the controller design and the control performance of the system are described with some results obtained both in a power plant simulation model and in the actual plants.
Lyapunov Optimal Feedback Control of a Nonlinear Inverted Pendulum
Authors: Anderson M. J. , Grantham W. J.
Published: July 2009

Lyapunov optimal feedback control is applied to a nonlinear inverted pendulum in which the control torque was constrained to be less than the nonlinear gravity torque in the model. This necessitates a control algorithm which “rocks” the pendulum out of its potential wells, in order to stabilize it at a unique vertical position. Simulation results indicate that a preliminary Lyapunov feedback controller can successfully overcome the nonlinearity and bring almost all trajectories to the target.
Automotive Powertrain Modeling for Control
Authors: Cho D. , Hedrick J. K.
Published: July 2009

A dynamic model of an automotive powertrain system is developed by the use of eight states and two time-delays in the continuous-time domain, with careful attention given to the dynamics and kinematics of a four-stroke spark-ignition engine, an automatic transmission, and rubber tires. The model is relatively simple, yet it predicts the important dynamics (including those during a shift) quite well when compared to experimental data. The model is well suited for developing powertrain controllers and can also be used for studying the dynamic behavior of a powertrain system. A great deal of effort was directed toward preserving the generic nature of modeling so that the developed techniques can be easily adapted to different vehicles with a minimum amount of bench tests for obtaining parameters.
The Nonlinear Behavior of Heavy-Duty Truck Combinations With Respect to Straightline Stability
Authors: Stribersky A. , Fancher P. S.
Published: July 2009

A comparison of the nonlinear stability behavior of the steady state straight line motion of truck combinations with and without a second trailer is shown. These investigations have been done by applying bifurcation theory. Stability boundaries in the parameter space and the corresponding bifurcation solutions are given. Depending on the loading conditions, unstable and also stable limit cycles have been found. Particular emphasis is given to the influence of the frictional coupling between tire and road on the nonlinear stability behavior of these vehicles.
Some Simple Two-Target Games
Authors: Breakwell J. V.
Published: July 2009

The paper deals with the game between a pursuer P and a slower evader E confined to a plane. The scenario considered by Skowronski and Stonier [1] required P to capture E before the latter reaches a shelter, and E to escape before he is captured, the objective achieved via Liapunov conditions. This paper augments the above work by considering a third game and introducing Isaacs’ barriers which interface with the Liapunov approach.
Tracking Controllers for Uncertain Systems: Application to a Manutec R3 Robot
Authors: Corless Martin
Published: July 2009

We consider a class of uncertain dynamical systems described by ordinary differential equations and characterized by certain structural conditions and known bounding functions. For a feasible class of desired state motions we present a class of controllers which assure asymptotic tracking to within any desired degree of accuracy. The results are applied to a general class of mechanical systems and are illustrated by a simple example and by application to a three degree-of-freedom model of a Manutec r3 robot.
A Short-Range Air Combat Study
Authors: Ja¨rmark Bernt
Published: July 2009

A short-range aerial duel with infrared missiles is the purpose with this study. The problem is solved numerically with a modified differential dynamic programming method. A new ingredient in the solution technique has to be implemented in the algorithm. This originates from the complex launch condition of the missiles. The paper emphasizes the game problem and the theoretical extension of the method. A simple case in the horizontal plane will be illustrated, which however is no limitation as a numerical method is used.
Controlled Chain of Pendulums
Authors: Bojadziev G.
Published: July 2009

A robotic manipulator with n links working in a vertical plane is modelled mathematically as a chain of pendulums linked together by rotational joints subjected to control torque. A control of motion program is designed so that the chain avoids an undesirable region.
Sensitivity of Structural Models for Noncollocated Control Systems
Authors: Spector V. A. , Flashner H.
Published: July 2009

This paper investigates sensitivity properties of structural models pertinent to robust control system design. Special emphasis is put on noncollocated systems. Sensitivity analysis to parameter variations and boundary conditions is performed on a representative example of a pinned-free beam with end-point mass and inertia and sensors distributed along the beam. The analysis utilizes a transfer matrix representation, which provides a convenient form for demonstrating the sensitivity of zeros and poles to sensors locations and system parameters. Investigation of the applicability of different structural models is also carried out. Comparison of the Euler-Bernoulli theory and Timoshenko beam theory is discussed and the range of parameters for which each theory is applicable is demonstrated.
Planar Pursuit-Evasion Subjected to Control Energy Constraint
Authors: Yavin Y. , deVilliers R.
Published: July 2009

This work deals with two stochastic planar pursuit-evasion differential games where the pursuer is subject to constraints on its control magnitude and its control energy, whereas the evader is subject only to a magnitude constraint on its control. In the first game the motion of the players is confined to the horizonal plane, while in the second their motion is confined to the vertical plane. In both games, owing to thrust, drag, and gravitational forces, the pursuer has a variable speed. The treatment is concerned mainly with the question of how far a certain type of proportional navigation guidance law is a good approximation to an optimal feedback pursuit strategy.
Experimental Validation of a Dynamic Model (Equivalent Rigid Link System) on a Single-Link Flexible Manipulator
Authors: Petroka R. P. , Chang Liang-Wey
Published: July 2009

Flexibility effects on robot manipulator design and control are typically ignored which is justified when large, bulky robotic mechanisms are moved at slow speeds. However, when increased speed and improved accuracy are desired in robot system performance it is necessary to consider flexible manipulators. This paper simulates the motion of a single-link, flexible manipulator using the Equivalent Rigid Link System (ERLS) dynamic model and experimentally validates the computer simulation results. Validation of the flexible manipulator dynamic model is necessary to ensure confidence of the model for use in future design and control applications of flexible manipulators.
The incidence of exercise-associated hyponatraemia in the London marathon
Authors: Kipps Courtney , Sharma Sanjay , Pedoe Dan Tunstall
Published: July 2009

Background

Exercise-associated hyponatraemia (EAH) is a potentially fatal cause of collapse in endurance exercise. It is understood to be a dilutional hyponatraemia caused by an increase of total body water relative to the amount of exchangeable sodium stores. Fourteen runners presented to one London hospital with symptomatic EAH several hours after finishing the 2003 London Marathon, and more recently, a young male runner died from the complications of severe EAH after crossing the finish line of the London Marathon.

Objectives

To determine the incidence of EAH in runners in the London Marathon.

Methods

Volunteers were recruited at race registration where they were weighed, had blood tests and completed a demographic and experience questionnaire. Weights, blood tests and a fluid intake questionnaire were repeated after the finish. Blood was analysed on-site using hand-held i-STAT blood analysers.

Results

Of the 88 volunteers, 11 (12.5%) developed asymptomatic hyponatraemia (serum sodium 128–134 mmol/l). They consumed more fluid (p<0.001) and gained more weight (p<0.001) than did those without hyponatraemia.

Conclusions

A significant proportion (12.5%) of healthy volunteers developed asymptomatic hyponatraemia running a marathon in cool conditions. On average, these runners consumed more fluid and gained more weight than did non-hyponatraemic runners, although fluid intake was not related to weight gain in this study. Four of the 11 hyponatraemic runners lost weight over the course of the marathon, strengthening the case for an additional factor, such as inappropriate antidiuretic hormone release during exercise, in the development of EAH.