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This paper presents a new dimmer that does not amplify light flicker in incandescent lamps. The development of this new dimmer is motivated by the fact that the incandescent lamp is very sensitive to voltage fluctuation and the typical R--C-circuit dimmer for incandescent lamps amplifies the light flicker considerably. The proposed method utilizes a 16-b microcontroller to calculate the fluctuation voltage and determine the appropriate firing angle for a power switch device in the circuit of the dimmer. The mathematical model and simulation of the incandescent lamp with the proposed dimmer are also presented. By dynamically adjusting the firing angle to compensate for the voltage, the proposed dimmer can substantially diminish the light flicker. Furthermore, a series of experiments on this dimmer has been made to test its performance, and the results demonstrate a remarkable reduction in amplifying effect of light flicker. Index Terms--Dimmers, incandescent lamps, microcontrollers, voltage flicker.

Author(s): Daniel Cressey A research subject watches a brush slowly stroking a rubber hand on a table in front of her, while her own hand - hidden from view - [...]

A microcontroiler based rotating magnetic stirring system has been developed in this study. A mathematical model is proposed to get electromagnetic field solutions. The magnetic stirring system consists of four-phase half-wound coils with phase currents of [lambda]/2 radian phase difference to achieve a rotating magnetic field. During the application, the liquid to be stirred is placed on the stirrer in a beaker and a magnetic stir bar in the form of a magnet rod is dipped in. The magnetic stir bar, influenced by the magnetic field supplied by the system, stirs the liquid rotating around the center of the rotational field. An adjustment of the frequencies of the voltage applied to these coils is done through a supply circuit with a developed PIC microcontroller. Within the scope of this study, operating principle and the mathematical model of the rotating magnetic stirring system have been discussed. Experimental results for the initial prototype are also presented in detail. Furthermore, parameter optimization for the stirrer is performed. Index Terms--Electromagnetic stirrer, magnetic stir bar, PIC microcontroller, rotating magnetic field.

Abstract: In this paper we have proposed the design of a DSP microcontroller where the processor load is significantly reduced by relegating the math-intensive DSP algorithm to dedicated transform computing [...]

In this paper, a new control system for the current-source active power filter is presented. The harmonic current compensation is realized using combined feedforward control of the load currents and closed-loop control of the supply currents. The control system includes a simple method for compensating the sampling and calculation delays of the digital control system. The compensation in the proposed method is achieved using the regular LC filter of the active power filter as an energy storage for load currents, and no additional components is needed in the main circuit. Furthermore, the calculation power demand of the compensation method is very low and is, therefore, suitable for single-chip microcontroller implementations. The proposed control system is realized using a 32-bit Motorola MPC555 microcontroiler. The simulation and experimental results show effective filtering performance also for higher order harmonics of the distorted load currents. Index Terms--Active filters, current-source converter, digital control, microcontrollers, power quality.

An analog superconducting quantum interference device (SQUID) readout electronics for diverse applications is developed. These analog circuits are embedded into a digitally-controlled system including an in-system programmable microcontroller on the electronics board and a user interface which runs on a personal computer, to improve the their user-friendliness and flexibility.

Fuzzy logic-based on-line efficiency optimization control has been described in the literature for an indirect vector-controlled induction motor drive. The purpose of this paper is to extend the same control to a stator flux-oriented electric vehicle induction motor drive and then implement the fuzzy controller by a dynamic back propagation neural network-based controller. The principal advantage of fuzzy control, i.e., fast convergence with adaptive step size of the control variable, is retained. The neural network adds the advantage of fast control implementation, either by a dedicated hardware chip or by digital signal processor (DSP)-based software. Index Terms - Drive, efficiency, fuzzy logic, induction motor, neural network.

In the ASDEX Upgrade tokamak, position and selected shape parameters are controlled by a parallel computer. Years of operational experience went into its redesign. Mapping the functionality of the algorithm into modules of code provides a sound base for extension to full shape control. A rule-based coordination layer guides controller action depending on discharge programmme and plasma and internal states.

Beyond optimization of position and shape control, producing high performance plasmas relies on precise and coordinated control of plasma parameters. This requires a universal platform, into which control algorithms can flexibly be integrated to adapt to interesting discharge scenarios. With the multitude of processes expected to be implemented, management of real time processes becomes crucial. In this paper we shall demonstrate how this issue is raised by the requirement specification of the controller and how it influences its design, implementation and operation.

A proportional, integral, and derivative (PID) type iterative learning controller is proposed for precise tracking control of industrial robots and computer numerical controller (CNC) machine tools performing repetitive tasks. The convergence of the output error by the proposed learning controller is guaranteed under a certain condition even when the system parameters are not known exactly and unknown external disturbances exist. As the proposed learning controller is repeatedly applied to the industrial robot or the CNC machine tool with the path-dependent repetitive task, the distance difference between the desired path and the actual tracked or machined path, which is one of the most significant factors in the evaluation of control performance, is progressively reduced. The experimental results demonstrate that the proposed learning controller can improve machining accuracy when the CNC machine tool performs repetitive machining tasks.

Today, home appliance applications require more and more features such as motor speed adaptations to multipurpose accessories, user friendly interfaces, and security features. Such new requirements can be achieved through a low-end microcontroller-based electronic control using the fuzzy logic approach. Nowadays, most of fuzzy logic-based controls are only limited to a complicated ranking management of user interfaces, sensors, and actuators, corresponding to a slow software speed operation. This paper proposes a totally different use of fuzzy logic. In this case, fuzzy logic is implemented in a standard microcontroller to regulate the speed of a universal motor by a real time adjustment (every 30 millisecond) of the motor current. This microcontroller directly tunes the motor current by means of a chopper converter. Starting from a basic food-processor application, the paper practically shows how a fuzzy logic approach can be applied to build a closed speed regulation loop from a very low cost tacho-generator. Practical guidelines are successively given from the initial concept analysis phase, up to the final generation of the executable code to be loaded in the microcontroller. The paper also gives the practical procedure to define the input parameters and to build fuzzy logic rules when using the fuzzy logic development tool. Finally, the major benefits of this paper lie in an original approach where fuzzy logic is applied to fast 'real-time' regulation loop without requiring any specific expertise in conventional methods of regulation. Benefits are discussed and concrete results are given.

The paper presents a rule-based fuzzy logic controller to control the output power of a pulse width modulated (PWM) inverter used in a stand alone wind energy conversion scheme (SAWECS). The self-excited induction generator used in SAWECS has the inherent problem of fluctuations in the magnitude and frequency of its terminal voltage with changes in wind velocity and load. To overcome this drawback the variable magnitude, variable frequency voltage at the generator terminals is rectified and the dc power is transferred to the load through a PWM inverter. The objective is to track and extract maximum power from the wind energy system (WES) and transfer this power to the local isolated load. This is achieved by using the fuzzy logic controller which regulates the modulation index of the PWM inverter based on the input signals: the power error e = ([P.sub.ref] - [P.sub.o]) and its rate of change [dot e]. These input signals are fuzzified, that is defined by a set of linguistic labels characterized by their membership functions predefined for each class. Using a set of 49 rules which relate the fuzzified input signals (e, [dot e]) to the fuzzy controller output U, fuzzy set theory and associated fuzzy logic operations, the fuzzy controller's output is obtained. The fuzzy set describing the controller's output (in terms of linguistic labels) is defuzzified to obtain the actual analog (numerical) output signal which is then used to control the PWM inverter and ensure complete utilization of the available wind energy. The proposed rule-based fuzzy logic controller is simulated and the results are experimentally verified on a scaled down laboratory prototype of the SAWECS.

A read-out controller (ROCK) has been developed for the Data Acquisition System of the KLOE High Energy Physics experiment, based in Frascati, Italy. The ROCK performs data acquisition in an event-driven fashion on the AUXbus, a custom high speed parallel bus. The AUXbus's main features are data cycles labeled by event number, sparse data scan operations and an asynchronous protocol optimized to achieve data rates up to 15 MHz. On a standard VMEbus, the ROCK allows for data snooping and real-time performance monitoring, without additional overhead on data acquisition. ROCK boards can be linked together via a custom cable bus (Cbus) to build a complex DAQ subsystem. The ROCK board has been designed around three 4.2K gate XILINX FPGAs. Dual port FIFO banks are used to decouple the asynchronous buses. A preliminary version of the board is presented and test results are briefly discussed.