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Friction Compensation for an Industrial Hydraulic Robot

IEEE control systems 1999年第1期19.0卷 25-32页

作者： Lischinsky, P. Canudas-de-Wit, C. Morel, G. Department of Automatic Control at the Systems Engineering School Universidad de Los Andes Merida Venezuela Department of Automatic Control Polytechnic Institute of Grenoble St-Martin-d'Heres Cedex France University of Strasbourg/ENSPS LSIIT/GRAVIR Illkirch France

A model based friction compensation scheme using a novel dynamical friction model was implemented on an industrial Schilling Titan II hydraulic robot. Off-line estimation of parameters was carried out, using the results of two kinds of experiments. These experiments were done independently at each joint. A nonlinear PI type controller was used in the inner torque loop to improve its performance. The complete control scheme has shown to substantially improve the position precision in regulation and tracking. Higher precision applications can be performed by the hydraulic robot with this controller.

关键词： Friction Service robots Actuators Manipulator dynamics Torque control Hydraulic systems Automatic control Force feedback Force control Robot control

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Analysis of multi-rate discrete equivalent of continuous controller

Analysis of multi-rate discrete equivalent of continuous con...

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American control Conference (ACC)

作者： J. Tornero Y. Gu M. Tomizuka Systems Engineering and Control Universidad Politecnica de Valencia Valencia Spain Department of Mechanical Engineering University of California Berkeley CA USA

The paper is concerned with the analysis of multi-rate controllers, which update the controller output faster than the measurement sampling frequency by a factor of N. The controlled system is continuous, and the discrete time controller is obtained as its zero order hold equivalent. After deriving a set of equations necessary for analysis and design of multi-rate systems, the open loop characteristics of the multi-rate controller and the closed loop characteristics are examined. Several physical meanings can be derived from the formulation of the multi-rate controller.

关键词： control systems Open loop systems Sampling methods Digital control Frequency measurement Feedback Equations Switches systems engineering and theory control system analysis

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control and dynamics of constant power loss based operation of permanent magnet synchronous motor drive system

Control and dynamics of constant power loss based operation ...

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Annual Conference of Industrial Electronics Society

作者： R. Monajemy R. Krishnan Motion Control Systems Research Group The Bradley Department of Electrical Engineering Virginia Polytechnic Institute and State University Blacksburg VA USA

The operational envelope of electrical machines is limited by the maximum permissible power losses of the machine. The control and dynamics of the permanent magnet synchronous motor (PMSM) drive operating with constant power losses is proposed in this study. The proposed operational strategy is modeled and analyzed. Its comparison to other control strategies that limit current and power, demonstrates the superiority of the proposed scheme. The implementation of the proposed scheme is developed. It is achieved with an outer power loss feedback control loop. This has the advantage of retrofitting the present PMSM drives with the least amount of software/hardware effort. The PMSM drives in this case then can use the existing controllers to implement the control criteria such as constant torque angle, unity power factor, constant air gap flux linkages, maximum torque per unit current or maximum efficiency operation. Experimental verification of the control strategy is provided.

关键词： Permanent magnet motors Motion control control systems Motor drives Torque control Robust control Feedback control Couplings Voltage control Shafts

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Performance comparison for six-step voltage and constant back EMF control strategies for PMSM

Performance comparison for six-step voltage and constant bac...

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Conference Record of the IEEE Industry Applications Society Annual Meeting (IAS)

作者： R. Monajemy R. Krishnan Motion Control Systems Research Group The Bradley Department of Electrical Engineering Virginia Polytechnic Institute and State University Blacksburg VA USA

Six-step voltage or constant back EMF control strategies can be applied to a permanent magnet synchronous motor (PMSM) in the flux weakening region in order to extend the motor's speed range. These two control strategies are compared on the basis of maximum torque vs. speed envelope, maximum current requirement, current and torque ripple, torque response and implementation complexity. The six-step voltage control strategy is shown to provide a significantly larger maximum torque vs. speed envelope, while the current requirements of both control strategies are in the same order. However, the six-step voltage control strategy exhibits higher current and torque ripples. It is shown that the magnitude of this torque ripple is relatively small and can be tolerated in most applications. The torque response of the constant back emf control strategy is higher than that of the six-step voltage control strategy. Analytical derivations of the maximum current and maximum speed in each case are provided. A procedure for deriving the instantaneous phase current and torque waveforms in steady state under the six-step voltage control strategy is presented. Experimental work in support of the key theoretical claims is provided.

关键词： Voltage control Torque control Motion control control systems Steady-state Computer hacking Pulse width modulation Permanent magnet motors Magnetic fields Copper

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An integer programming model for vaccine procurement and delivery for childhood immunization: A pilot study

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Health Care Management Science 1999年第1期2.0卷 1-9页

作者： Jacobson, Sheldon H. Sewell, Edward C. Deuson, Robert Weniger, Bruce G. Department of Industrial and Systems Engineering Virginia Polytechnic Institute State University Blacksburg VA 24061 United States Department of Mathematics and Statistics Southern Illinois University at Edwardsville Edwardsville IL 62026-1653 United States Immunization Services Division National Immunization Program Centers for Disease Control and Prevention Atlanta GA 30333 United States Vaccine Safety and Development Activity National Immunization Program Centers for Disease Control and Prevention Atlanta GA 30333 United States

The National Immunization Program of the Centers for Disease control and Prevention has identified several challenges that must be faced in childhood immunization programs to deliver and procure vaccines to protect against the common preventable diseases. The biomedical challenge is how to combine and formulate products to take advantage of new vaccines without requiring additional injections. A programmatic challenge is to incorporate them into already crowded immunization schedules. The economic challenge is to make wise procurement choices from among a growing number of competing products. This paper reports the results of a pilot study using operations research methodologies to address the third of these challenges. The pilot is an integer programming model for procuring vaccines for a set of childhood diseases. The model is studied under various scenarios (minimum total cost, next lowest total cost, maximum total cost, minimum total cost with all manufacturers represented). The results of this pilot study demonstrate how a practical set of operations research tools can be developed to guide vaccine selection and procurement, which might stimulate the development of innovations in new vaccines to meet the challenges of disease control through immunization. © Baltzer Science Publishers BV.

关键词： Economics Integer programming model health-care applications Mathematical programming Vaccines

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A variable voltage converter topology for permanent-magnet brushless DC motor drives using buck-boost front-end power stage

A variable voltage converter topology for permanent-magnet b...

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IEEE International Symposium on Industrial Electronics (ISIE)

作者： B.-S. Lee R. Krishnan Motion Control Systems Research Group Department of Elec. & Computer Engineering Virginia Polytechnic Institute and State University Blacksburg VA USA

A variant of a low cost, four-quadrant converter topology for permanent magnet brushless DC (PMBDC) motor drives is proposed in this paper. It has the advantage of variable DC input voltage to the machine through a buck-boost front-end power stage and hence low torque ripple at very low speeds, a desirable feature in high performance applications. It has a fixed commutation voltage, which is equal to the DC source voltage. Further, it is proved that the proposed power converter topology will enable the maximum extraction of power from PMBDC motor drives. In addition, the energization and commutation of machine phases can be achieved independently. Because of these features, the proposed topology provides high operational reliability for the motor drives.

关键词： Voltage Brushless DC motors Motor drives Switches Circuit topology Switching converters Costs Circuit faults Reluctance motors Commutation

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Design of a linear switched reluctance machine

Design of a linear switched reluctance machine

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Conference Record of the IEEE Industry Applications Society Annual Meeting (IAS)

作者： Byeong-Seok Lee Han-Kyung Bae P. Vijayraghavan R. Krishnan Bradley Department of Electrical and Computer Engineering Motion Control Systems Research Group Virginia Polytechnic Institute and State University Blacksburg VA USA

A standard design procedure for a single sided and longitudinal flux based linear switched reluctance machine is developed in this paper. The proposed design procedure utilises the rotating switched reluctance machine design by converting the specifications of the linear machine in to the equivalent rotary machine. The machine design is carried out in the rotary domain which is then transformed back in to the linear domain. Such a procedure brings to bear the knowledge base and familiarity of the rotary machine designers to design a linear machine effectively. The paper contains the illustration of the proposed design procedure for a 4.8 m long prototype. An analysis procedure is developed with a magnetic model and results from it are verified with finite element analysis prior to construction of the prototype. Extensive experimental correlation in the form of inductance vs. position vs. current and propulsion force vs. position vs. current to validate the analysis and design procedure is given in the paper.

关键词： Reluctance machines Finite element methods Prototypes Magnetic analysis Inductance Propulsion Torque Equations Motion control Standards development

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Efficient generation of object hierarchies from 3D scenes

Efficient generation of object hierarchies from 3D scenes

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IEEE International Conference on Robotics and Automation (ICRA)

作者： M.A. Garcia A.D. Sappa L. Basanez Department of Computer Science Engineering Rovira i Virgili University Tarragona Spain Inst. of Organization and Control of Industrial Systems Polytechnic University of Catalonia Barcelona Spain

Describes an efficient technique for computing a hierarchical representation of the objects contained in a complex 3D scene. First, an adjacency graph keeping the costs of grouping the different pairs of objects in the scene is built. Then the minimum spanning tree (MST) of that graph is determined. A binary clustering tree (BCT) is obtained from the MST. Finally, a merging stage joins the adjacent nodes in the BCT which have similar costs. The final result is an n-ary tree which defines an intuitive clustering of the objects of the scene at different levels of abstraction. Experimental results with synthetic 3D scenes are presented.

关键词： Layout Clustering algorithms Tree graphs Costs Approximation error Computer science control systems Electrical equipment industry Industrial control Merging

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Further results on tracking control of nonholonomic chained systems

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IFAC Proceedings Volumes 1999年第2期32卷 1172-1177页

作者： Zhong-Ping Jiang Henk Nijmeiger Department of Electrical Engineering Polytechnic University Six Metrotech Center Brooklyn NY 11201 U.S.A. Faculty of Mathematical Sciences Dept of Systems Signals and Control University of Twente P.O. Box 217 7500 AE Enschede The Netherlands

In this paper we deal with the state-feedback tracking control problem for a class of nonholonomic dynamic systems in chained form. By means of the recursive technique proposed in our recent work, we first show that the semiglobal exponential tracking can be easily obtained for systems in chained form. Then, we show that, whenever the control inputs are subject to saturation constraints, a semiglobal asymptotic tracking controller can be found on the basis of Lyapunov redesign and backstepping techniques.

关键词： Nonlinear control mechanical systems tracking saturation control

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Force control for flexible robots using neural networks

Force control for flexible robots using neural networks

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American control Conference (ACC)

作者： J. Borowiec A. Tzes Network Wireless Systems Product Design & Realization Lucent Technologies Inc. Whippany NJ USA Control/Robotics Research Laboratory Mechanical Engineering Department Six Metrotech Center Polytechnic University Brooklyn NY USA

Force control for flexible link robots using neural networks is considered. The nonlinear dynamics of the robot manipulator are identified through a recurrent neural network (RNN), which is trained in an off-line manner. Inversion of the RNN-based model dynamics leads to a feedforward component. The feedback controller gains are derived from the minimization of a discrete linear quadratic cost functional, subject to the model dynamics inferred by the linearization of the neural network along the desired trajectory. Sufficient conditions for temporal gain switching bounds are provided. The proposed control scheme is employed in simulation studies on a two link rigid-flexible manipulator.

关键词： Force control Neural networks Manipulator dynamics Recurrent neural networks Force feedback Jacobian matrices Adaptive control Cost function Robot kinematics Torque

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