Magnetically levitated micro PM motors by two types of activemagnetic bearings

This paper describes magnetically levitated micro permanent magnet (PM) motors by two types of active magnetic bearings. The micro PM motors consist of a cylindrical rotor (φ2.0 mm×10 mm), a pair of electromagnets, a pair of photodiodes, and an analog PD controller. The motors are characterized by the small rotor levitated without any mechanical contacts and one-axis controlled active magnetic bearing. Horseshoe-shaped and cylindrical electromagnets are applied to the active magnetic bearing. The rotor successfully rotates, levitating in the center of the electromagnets. In this paper, dynamic characteristics of the two types of micro PM motors, such as relationships between rotation speed and driving current, rotation speed and time, and acceleration and driving current, are discussed. As a result, it is found that the magnetically levitated micro PM motors by two types of active magnetic bearings are very different from each other and very promising     

Nonlinear coupling control laws for an underactuated overhead crane system

In this paper, we consider the regulation control problem for an underactuated overhead crane system. Motivated by recent passivity-based controllers for underactuated systems, we design several controllers that asymptotically regulate the planar gantry position and the payload angle. Specifically, utilizing LaSalle's invariant set theorem, we first illustrate how a simple proportional-derivative (PD) controller can be utilized to asymptotically regulate the overhead crane system. Motivated by the desire to achieve improved transient performance, we then present two nonlinear controllers that increase the coupling between the planar gantry position and the payload angle. Experimental results are provided to illustrate the improved performance of the nonlinear controllers over the simple PD controller.     

Adjustable speed control of ultrasonic motors by adaptive control

The driving principle of the ultrasonic motor (USM) is different from those of the electro-magnetic type motors. Some mathematical models for the USM have been reported; however, these models are very complex to apply for speed control of the USM. Therefore, the speed controllers have been designed using PI controllers or fuzzy controllers and it is necessary to develop a simple and convenient mathematical model for the USM in order to achieve a high-performance speed control. In this paper, a mathematical model for the USM is proposed which is simple and useful for speed control. The speed controller is designed based on the model using adaptive control theory. Adaptive control is attractive for control of the USM because the speed characteristics of the USM vary with drive conditions. The application of this control scheme to speed control for the USM is attempted first. The effectiveness of proposed control is demonstrated by experimental     

Design of an Adaptive Controller for Microcomputer Implementation

A design procedure for an adaptive controller is described and applied to the design of a velocity controller for small dc motors. The basic concept has been to determine a small set of controllers each of which is capable of maintaining stability and acceptable performance over a specific region of motor load parameters. Optimal control theory is used to define the control coefficients while cluster analysis and decision function techniques from pattern recognition theory are used to determine each controller's region of applicability. Simulation results are presented to verify performance improvements using the design procedure. The design procedure produces an adaptive controller which is computationally feasible for implementation in small microcomputer systems.     

Comments on "Passivity-based control of saturated induction motors"

The authors comment on the paper by L.U. Gokdere et al. (see ibid., vol. 48, p.870-2, 2001). A review of the experimental evidence shows that passivity-based control of saturated induction motors does not provide superior performance over input-ouput linearization. Higher tracking errors can be observed and traced to the open-loop nature of the flux controller. In contrast, input-output linearization controllers achieve close tracking of flux, speed, and position references for the most demanding trajectories.     

Quasi-resonant-converters-based high-efficiency spindle motor drives for magnetic data storage

Disk drive spindle motors require accurate speed control and highly efficient drive controllers. Small-volume and high-efficiency converters are of particular interest for portable data storage applications. Quasi-resonant voltage controllers are described in this paper and the experimental results are presented. In contrast to the conventional pulsewidth-modulated voltage controller, this technique reduces the switching loss and enables the controller to operate at very high frequencies. Three types of resonant converters are built and tested for the application. A comparison of performance in terms of losses and voltage regulation is given.     

Technology 1992-industrial electronics

Important trends and events are highlighted. The use of fuzzy logic expanded. The use of programmable logic controllers in distributed control made headway. Low-cost vision systems were introduced, as were faster X-ray laminography systems. Growing emphasis on keeping humans who work around robots safe was evident. More robust motion and speed controls for both robots and motors became available     

Direct torque control of PWM inverter-fed AC motors - a survey

This paper presents a review of recently used direct torque and flux control (DTC) techniques for voltage inverter-fed induction and permanent-magnet synchronous motors. A variety of techniques, different in concept, are described as follows: switching-table-based hysteresis DTC, direct self control, constant-switching-frequency DTC with space-vector modulation (DTC-SVM). Also, trends in the DTC-SVM techniques based on neuro-fuzzy logic controllers are presented. Some oscillograms that illustrate properties of the presented techniques are shown.     

Nonlinear control of mechatronic systems with permanent-magnet DC motors

The current trends in development and deployment of advanced electromechanical systems have facilitated the unified activities in the analysis and design of state-of-the-art motion devices, electric motors, power electronics, and digital controllers. This paper attacks the motion control problem (stabilization, tracking, and disturbance attenuation) for mechatronic systems which include permanent-magnet DC motors, power circuity, and motion controllers. By using an explicit representation of nonlinear dynamics of motors and switching converters, we approach and solve analysis and control problems to ensure a spectrum of performance objectives imposed on advanced mechatronic systems. The maximum allowable magnitude of the applied armature voltage is rated, the currents are limited, and there exist the lower and upper limits of the duty ratio of converters. To approach design tradeoffs and analyze performance (accuracy, settling time, overshoot, stability margins, and other quantities), the imposed constraints, model nonlinearities, and parameter variations are thoroughly studied in this paper. Our goal is to attain the specified characteristics and avoid deficiencies associated with linear formulation. To solve these problems, an innovative controller is synthesized to ensure performance improvements, robust tracking, and disturbance rejection. One cannot neglect constraints, and a bounded control law is designed to improve performance and guarantee robust stability. The offered approach uses a complete nonlinear mechatronic system dynamics with parameter variations, and this avenue allows one to avoid the conservative results associated with linear concept when mechatronic system dynamics is mapped by a linear constant-coefficient differential equation. To illustrate the reported framework and to validate the controller, analytical and experimental results are presented and discussed. In particular, comprehensive analysis and design with experimental verification are performed for an electric drive. A nonlinear bounded controller is designed, implemented, and experimentally tested.     

Coordination mechanisms for multi-agent manufacturing systems:applications to integrated manufacturing scheduling

The advent of information technology (IT) has made today's manufacturing systems increasingly distributed. Typically such a system consists of a complex array of computer-based decision units, controllers and databases. Rather than dealing with each component individually, it is necessary to have a new paradigm for management of manufacturing systems, so that all the components and their operations can be managed in an integrated fashion. The multi-agent framework presented in this paper is such a paradigm for achieving system integration. The authors specifically emphasize the coordination mechanisms needed for ensuring the orderly operations and concerted decision making among the components-i.e., agents-of the manufacturing systems. The application of the framework to a printed circuit board manufacturing system and the performance results are also described     

San Francisco MUNI trolleybus propulsion tests: The results

The San Francisco Municipal Railway (MUNI) fleet of 345 trolleybuses, the largest in North America, is powered by dc motors with switched resistor controllers. Under an Urban Mass Transportation Administration (UMTA) grant, MUNI conducted a Trolleybus Propulsion Evaluation Program, in which the energy use and performance were measured of the existing switched resistor dc motor controller and three chopper and ac propulsion systems. For each of the systems, tests were conducted on level, medium, and hilly routes, with empty, seated, and crush loads. Graphical analyses are presented, comparing net propulsion energy, regenerated energy, control losses, net motor energy, and rheostatic braking losses for the four systems. Advanced systems are shown to reduce propulsion energy use by an aggregate average of 39 percent compared to the switched resistor controller.     

A two-layered fuzzy logic controller for systems with deadzones

Existing fuzzy control methods do not perform well when applied to systems containing nonlinearities arising from unknown deadzones. In particular, we show that a usual "fuzzy PD" controller applied to a system with a deadzone suffers from poor transient performance and a large steady-state error. In this paper, we propose a novel two-layered fuzzy logic controller for controlling systems with deadzones. The two-layered control structure consists of a fuzzy logic-based precompensator followed by a usual fuzzy PD controller. Our proposed controller exhibits superior transient and steady-state performance compared to usual fuzzy PD controllers. In addition, the controller is robust to variations in deadzone nonlinearities. We illustrate the effectiveness of our scheme using computer simulation examples.<>     

Implementation of a neural network tracking controller for a singleflexible link: comparison with PD and PID controllers

The objective of this paper is to show the results of the practical implementation of a neural network (NN) tracking controller on a single flexible link and compare its performance to that of proportional derivative (PD) and proportional integral derivative (PID) standard controllers. The NN controller is composed of an outer PD tracking loop, a singular perturbation inner loop for stabilization of the fast flexible-mode dynamics, and an NN inner loop used to feedback linearize the slow pointing dynamics. No off-line training or learning is needed for the NN. It is shown that the tracking performance of the NN controller is far better than that of the PD or PID standard controllers. An extra friction term was added in the tests to demonstrate the ability of the NN to learn unmodeled nonlinear dynamics     

From "macro" to "micro" manipulation: models and experiments

This paper addresses various problems related to manipulation in the micro domain, a field which is increasingly important for research and application. Grasping and manipulating parts with size ranging between a few micrometers and about 1 millimeter (defined in this paper as "micro parts") are required for an increasing number of applications: the assembly of micro systems and micro machines; and the operation in tiny and unpredictable environments, such as for inspection and interventions in pipes and for micro surgery. The aim of this work is to find out similarities and differences between traditional manipulation and micro manipulation, by investigating which requirements are still valid and which must be redefined when the object size scales down. The similarities between the two application domains "macro" and "micro" are pointed out along with the differences, and both are taken into account for the evaluation of different grasping typologies. Dedicated models for the adhesion forces arising at the micro level are presented, preliminarily tested, and discussed.     

Performance benefits of hybrid control design for linear andnonlinear systems

This paper provides an overview of recent developments on design of hybrid controllers for continuous-time control systems that can be described by linear or nonlinear differential state equations. Hybrid controllers provide a generalization of classical feedback controllers for linear and nonlinear systems. The benefit of hybrid controllers, that they can be used to achieve closed-loop performance objectives that cannot be achieved using classical linear or nonlinear controllers, is emphasized. This paper introduces hybrid controllers in the form of a switching control architecture and provides a summary of recently developed control approaches that utilize this control architecture. We provide a conceptual framework for these results, identify limitations of the results, and discuss the current status of hybrid control design approaches     

HIST: A hierarchical self test methodology for chips,boards, and systems

This article presents the HIST approach, which allows the automated insertion of self test hardware into hierarchically designed circuits and systems to implement the RUNBIST instruction of the IEEE 1149.1 standard. To achieve an optimal and throughout self testable system, the inherent design hierarchy is fully exploited. All chips and boards are provided with appropriate test controllers at each hierarchy level. The approach is able to detect all those faults, which are in the scope of the underlying self test algorithms. In this paper the hierarchical test architecture, the test controllers as well as all necessary synthesis procedures are presented. Finally a successful application of the HIST approach to a cryptography processor is described.     

Robust control of permanent magnet motors: VSS techniques lead tosimple hardware implementations

It is shown how very simple velocity-tracking robust controllers for permanent magnet motors driving nonlinear loads can be designed based on variable structure systems techniques. Very fast dynamics, accurate and robust velocity-tracking are achieved with very simple hardware components without resorting to powerful digital signal processors and related interface hardware. A cascade control structure is used to ensure maximum flexibility. The controller for a DC motor is considered in great detail. Extension to AC synchronous PM motors is also presented. At the different control levels robustness is addressed with specific algorithms and the simplest solution is always selected. The controller architecture for both DC and AC synchronous motor are presented and discussed in the paper. Experimental results related to the control of a DC motor driving a nonlinear load are also shown. They demonstrate feasibility and excellent performances of the proposed approach     

Robust Positive Real Synthesis for 2D Continuous Systems via State and Output Feedback

This paper considers the problem of positive real control for uncertain twodimensional (2D) continuous systems described by the Roesser state-space model. The parameter uncertainties are assumed to be norm bounded in both state and measurement output equations. The purpose is the design of controllers such that the resulting closed-loop system is asymptotically stable and strictly positive real for all admissible uncertainties. A version of the positive realness of 2D continuous systems is established. Then, sufficient conditions for the solvability of the positive real control problem via state feedback and dynamic output feedback controllers, respectively, are proposed. A linear matrix inequality approach is developed to construct the desired controllers. Finally, an illustrative example is provided to demonstrate the applicability and effectiveness of the proposed method.     

Microcomputer systems for chemical process control

Microcomputer systems for application to chemical process monitoring and control are presented. Recently developed modular components which expand the utility of 8-bit microcomputers in data-logging and monitoring systems, process-sequence controllers, and direct-digital process controllers are described.