Showing papers on "Open-loop controller published in 1985"

An Adaptive Power Factor Controller for Three-Phase Induction Generators

Abstract: An adaptive power factor controllerfor three-phase inducti on generators (and also for motors) is proposed in this paper. The controller senses the reactive current drawn by the machine and accordingly provides the needed reactive power to improve the power factor to as close to unity as possible. The controller is a modular, low-cost, harmonic free device. It does not create any transients in line current. It is designed to eliminate the self-excitation problems associated with induction generators. The controller is tested on an induction generator, which is being used in wind energy and similar applications.

Digital controllers for SISO systems: a review and a new algorithm

Abstract: Several digital control algorithms for linear single-input single-output systems are examined and the effect of the sampling period on their performance is analysed in terms of rippling, overshoot and settling time. The problem is addressed in the frequency domain (z-transform) and it is shown that each controller works for some classes of systems but that none works for all. The similarities and differences of these controllers are established and an explanation of their deficiencies is given based on the location of the zeros of the discrete system. The insight gained leads to a simple new rule for the design of a controller which combines the advantages of the different algorithms but at the same time is free of their problems. A single tuning parameter is included which directly affects the closed-loop speed of response and bandwidth. The parameter can be used to detune the controller in the event that the real system differs from the model on which the controller design is based. No tuning is necessa...

Practical application of a heuristic fuzzy rule-based controller to the dynamic control of a robot arm

Abstract: The paper reports results of the practical application of the self-organising controller to the simultaneous control of two interacting joints of a robot. The rationale for its use and the architecture of this heuristic fuzzy rule-based dynamic control approach are outlined. This shows it to be a relatively simple intelligent knowledge-based system capable of both learning and displaying a variable nonlinear input/output relationship. In both step response and tracking experiments the self-organising controller was found to perform better than a conventional PID controller under similar circumstances, although some tuning was required for the former system.

Microprocessor based motor control

Abstract: A microprocessor based motor controller which provides open loop speed control at low conduction angles, closed loop speed control at high conduction angles, and a smooth transition between open loop and closed loop zones. In open loop, the motor speed is selected and is permitted to vary with applied load. In closed loop, the motor speed is held constant, substantially irrespective of load. In the transition zone, the motor is operated in a hybrid open loop, closed loop fashion. Anti-kickback protection is also provided based on a percentage change in the motor's rotational period.

On the design of a vehicle longitudinal controller

Abstract: A methodology for designing an automated vehicle longitudinal controller is presented and applied to an automobile characterized by velocity-dependent dynamics. The design consists of a cascade compensator, which is selected to achieve small tracking errors, and an observer/controller compensator. The controller portion was designed to achieve a velocity-invariant response, and the observer to derive the state-feedback signals. Both compensators were realized on an eight-bit microcomputer, and the vehicle dynamics were simulated on an analog computer. The performance of the resulting system was evaluated using a large-signal, entry merging command and small-signal mainline commands. Excellent results were obtained with typical values being a maximum position error of 0.63 m during an entry maneuver and 0.15 m during a mainline maneuver; however, the designed system was sensitive to large changes in critical vehicle parameters. Thus, there is a need to modify the controller so that it can adaptively compensate for such changes. Then, the designed digital controller, with its flexibility to perform other functions and its ease of reliability enhancement, is an attractive candidate for implementation, and at the very least, indicates the type of longitudinal performance one can expect from a realistically designed controller over the speed range 0-30 m/s.

Infinity-Norm Optimization with a Stable Controller

Abstract: The stability of a feedback system with an open-loop stable controller is discussed, and an optimality condition in the infinity norm sense is derived in the MIMO case.

System for coupling a visual sensor processor and a robot controller.

Abstract: A system for coupling a visual sensor processor B and a robot controller A, in order to inexpensively constitute the whole system while maintaining increased processing speed. For this purpose, the visual sensor processor B and the robot controller A are couplped together through bidirectional high-speed data transfer channels (10, 28, /1, /2), so that the data required for the two apparatuses can be exchanged through these channels. Utilizing these channels, furthermore, a non-volatile memory (6) and serial interface (12) for connection to an external input/output device, installed in the robot controller A, are commonly used for these two apparatuses.

Initialization apparatus for a data processing system with a plurality of input/output and storage controller connected to a common bus.

Abstract: A plurality of controllers are connected to a common bus (11) in turn connected to a central processor (10). Each of the controllers (18, 19, 19A) respectively serves as an interface between the central processor and at least one storage unit (12, 13) or input/output device (14). In order for the controllers to distinguish between addresses, the addresses sent from the central processor contain identifier segments indicative of the controller to which the address is being sent. Controllers in turn contain programmable comparison means (20, 21, 22) for comparing the identifier segments in addresses to a stored controller identifier indicative of the controller. Because the comparison means are programmable, controller identifiers have to be set up each time the system is turned on. Consequently, the present invention provides such turn on or initialization means including a read-only initialization program stored in one of the storage units: the controller interfacing with this storage unit becomes a master controller; the master controller has apparatus which is selectively activated only during initialization for accepting all addresses irrespective of the identifier segment. The other controllers have apparatus selectively activated only during initialization for disabling the comparison means and such other controllers so that no addresses are accepted by the other controllers during the initialization. In other words, the comparison means in the master controller is completely bypassed during initialization whereby the read-only initialization program is accessed only through the master controller.

Evaluation of simple dynamic models and controllers for hydraulic and nozzle pressure in injection molding

Abstract: Simple pseudo-steady state relations between the hydraulic and nozzle pressures of an injection molding machine were presented and verified experimentally. A simulation study was performed to evaluate the performance of simple controllers using dynamic models developed for the hydraulic and nozzle pressures. The controllers chosen were the discrete proportional, proportional-integral (PI), and proportional-integral-derivative (PID) types, tuned according to the ITAE criterion. The control of hydraulic pressure simulation showed that the PI controller had the best overall performance, whereas the result of nozzle pressure control loop simulation showed that the PID controller performance was better than that of the PI controller. All the controllers, in both loops, gave responses that were about an order of magnitude more rapid than the open loop response.

High-speed digital controllers using an 8 bit microprocessor

Abstract: Structures and algorithms for implementation of digital filters are described which enable highperformance controllers using 8 bit microprocessors to be designed. Using these techniques a typical controller for an electromechanical system incorporating two feedback signals, a phase advance compensator, a notch filter and a proportional-plus-integral term can operate at up to 750 Hz sampling frequency. The paper summarises the development of the structure for the digital filters within the controller, describes the number format for the variables and coefficients, and outlines the software techniques employed to facilitate particular controller implementations.

Stable Direct Adaptive Control of Linear Infinite-dimensional Systems Using a Command Generator Tracker Approach

Abstract: A command generator tracker approach to model following contol of linear distributed parameter systems (DPS) whose dynamics are described on infinite dimensional Hilbert spaces is presented. This method generates finite dimensional controllers capable of exponentially stable tracking of the reference trajectories when certain ideal trajectories are known to exist for the open loop DPS; we present conditions for the existence of these ideal trajectories. An adaptive version of this type of controller is also presented and shown to achieve (in some cases, asymptotically) stable finite dimensional control of the infinite dimensional DPS.

Real-time evaluation of robotic control methods

Abstract: Design modifications on the controller of the PUMA- 600 arm are required to apply modern control techniques in real-time. These modifications are performed on the computer-level and the joint control level of the PUMA controller. Real-time closed loop control of the arm is thus made possible. The paper compares the performance of various control algorithms in real-time and by simulation.

Approaches to Design of Ministepping Step Motor Controllers and Their Accuracy Considerations

Abstract: This paper describes methods of calculating current references for ministepping step motor controllers. An implementation based on piecewise-linear interpolation from motor characteristic curves is presented. This method takes into account motor nonlinearities. Ministepping accuracy so obtained is compared with those of other controllers.

Method for controlling process variables in motor vehicles

Abstract: A method for controlling process variables is proposed in which an adaptive optimum cut-in controller is used. The cut-in controller is supplemented by an adaption block which automatically sets the controller parameters. In this way, the control circuit behaves in an optimum fashion under all operating conditions in accordance with its design. The adaption block comprises essentially a Kalman filter and an identification algorithm. The control method is suitable in particular for travel speed controllers or idling speed controllers in motor vehicles.

Control system for microwave cooking appliance

Abstract: A control system for a microwave oven includes a magnetron power circuit, an electronic controller, and input control circuitry. The control system is adapted to be connected to a source of electrical power, typically an AC line supply. The line supply may be converted to DC for powering the electronic controller, however, the input control circuitry is structured to prevent connection of the power supply to the electronic controller until an intentional manual action occurs. This prevents the electronic controller from responding to noise or the like to become unintentionally powered and thus possibly operate in an undesired state. The input control circuitry includes switches associated with data input keys for temporarily connecting power to the controller when actuated. Such actuation of a data key enables the system to be powered-up and also to enter data.

Design of adaptive digital set-point tracking PID controllers incorporating recursive step-response matrix identifiers for multivariable plants

Abstract: It is shown that, by incorporating fast on-line recursive identifiers to provide updated step-response matrices for inclusion in digital PID control laws, highly effective adaptive digital set-point tracking controllers can be readily designed for multivariable plants. The effectiveness of such an adaptive controller is illustrated by designing a digital set-point tracking controller for a distillation column.

Application of Time Optimal Control to the Scole Configuration

Abstract: The large-angle, nonlinear slew of the Spacecraft Control Laboratory Experiment (SCOLE) is treated with the assumption that the body is rigid The optimal axis of rotation is first determined and then a time-optimal, bang-bang controller is designed The controller is implemented in both open-loop and closed-loop form in a numerical simulation using DISCOS Results are presented which demonstrate controller performance with respect to dynamic coupling compensation, size of the integration time step, and time delay in the response of sensors This work establishes the theoretical limit of expected performance and provides a foundation upon which a complete, flexible-body control methodology will be developed

Glassware forming apparatus with distributed control and method of operation

Abstract: An improved electronic control system for glassware forming apparatus having a hierarchy of machine level supervisory controllers (including a machine controller and an operator communications controller), section controllers, and individual mechanism controllers. The mechanism controllers may be dedicated to the control of a variety of functions admitting of automated control, such as servo-control of electrical motors, sequencing of solenoid valves, generating alarm signals, etc. The mechanism controllers include separate control programs designed for their associated forming mechanisms, and are subject to on-off timing control in real time from the section level controllers. In general, the machine controller and operator I/O controller handle set-up, operator modifications during operation, and other "non-real-time" interactions with the mechanism controllers; the machine controller also coordinates the operation of a plurality of mechanism controllers in accordance with machine-level parameters.

Temperature controller for circuit board under conveyance

Abstract: PURPOSE: To melt solder without breaking down circuit boards to be conveyed by inputting the data corresponding to said circuit boards, selecting the data of a memory means in accordance with the data and controlling heating and cooling temp. as well and conveying speed. CONSTITUTION: The data corresponding to the circuit board 17 is inputted to a data transmitter 1 when the circuit board 17 is conveyed in a direction F on a chain conveyor 16. A selector 2 selects the data of the memory means 3 in accordance with the data from the transmitter 1. The selected data is then transmitted to a temp. controller 5, a speed controller 4 and an air flow controller 39. The temp. controller 5 controls far IR heaters 6, 7, 8, 9 and near IR heaters 10, 11 and the air flow controller 39 controls a cooling fan 12. The speed controller 4 controls the speed of the chain conveyor 16 to prevent the thermal damage on the circuit board 17. COPYRIGHT: (C)1987,JPO&Japio

Controller backup method

Abstract: PURPOSE: To permit a little backup controllers to cope instantaneously with a case where a normal controller is troubled by loading control mechanism programs of M-units of controllers with priority among N-units of normal ocntrollers on a backup controller. CONSTITUTION: The control system of a power plant is provided with N-units of normal controllers 19, M-units of backup controllers 26 and a program loading device 16 provided with a function loading a function program to each controller 19. The priority order of each normal controller 19 is decided in accordance with the hourly sections of operating stages from the activation, operation and stop of the power plant on the basis of the states of the plant and controller at each stage. According to the priority order, the function program of the normal controller 19 is previously loaded on the backup controller 16. Thus the backup controllers less than the normal controllers cope instantaneously with the case where the normal controller 19 is troubled, thereby executing the backup of the control function of the troubled controller. COPYRIGHT: (C)1986,JPO&Japio

A dual controller for linear systems with random jump parameters

Abstract: This paper addresses the problem of control of partially observed linear discrete time stochastic systems with unknown parameters taking values in a finite set. The solution approach is based on a decomposition of the cost function into a control and trajectory component and a dual or learning component. Similarly the control policy is decomposed into a trajectory and a dual policy. A novel identification feedback scheme which introduces duality into the problem is presented.

On the Trade-Off between Noise Sensitivity and Robustness for LQG-Regulators

Abstract: A design method that makes a trade-off between noise reduction and stability requirements is suggested in the case when the process is modelled as a time invariant linear stable plant. The suggested controller is obtained by modifying the well known LQG-controller. Only the SISO-case is treated here. We give analytical expressions on how stability margins can be improved and how the stochastic properties will change using the suggested nonoptimal controller.

Controller for an industrial welding robot

Abstract: The invention relates to a controller for an industrial welding robot having integrated welding control. The welding parameters are also stored in the program memory of the actual robot controller, which welding parameters can be called up at the correct time and can be converted, by means of a programmable memory controller, into triggering commands for the welding-current controller.

Switched control of frequency of interconnected power systems using variable structure

Abstract: This paper proposes a new technique based on eigenvalue assignment for the design of a variable structure load frequency controller for interconnected power systems. An important feature of the variable structure controller is that it can effectively improve the transient performance of the system while at the same time ensuring zero steady-state error. Further, when the variable structure system is operated in the so-called sliding mode, the response of the system becomes insensitive to plant parameter variations. The control problem is formulated and the results of a digital simulation study are presented for illustration. For comparison purposes, results obtained using a conventional integral controller and a linear optimal controller are also included.