Showing papers on "Open-loop controller published in 1987"

Suboptimal control of linear systems with state and control inequality constraints

Abstract: A suboptimal controller based upon on-line quadratic programming is described. Theoretical results are presented to show that such a controller is optimal under the assumption that there are no constraints on the computation time. Finally, an implementation of a suboptimal controller that takes such constraints into account is described.

Secondary storage facility employing serial communications between drive and controller

Abstract: In a system including a plurality of mass storage devices at least one of which includes first and second ports, a plurality of controllers and cables coupling the ports to various ones of the controllers and in which each device can only be on-line through one port at a time, state information is sent from the on-line port of each device to a first controller to which it is coupled until a predetermined command from the controller to the on-line port is sent by the first controller. The device responds to the predetermined command by discontinuing the sending of state information from the on-line port to the first controller, and sending a state available signal from the other port to the second controller while maintaining the actual state of said device unchanged, permitting the other controller to interrogate the device as an aid in determining system topology.

Control characteristics and speed controller design for a high performance permanent magnet synchronous motor drive

Abstract: This paper applies the theory of vector control to the nonlinear model of a permanent magnet synchronous motor to develop a linear model for controller design purposes. The operation and relevant mathematics of a pseudo derivative feedback controller is then presented. Three different speed controller designs are then considered and a comparative evaluation made based on their large and small signal behavior. In order to test the large signal response, the detailed nonlinear model of the machine and real time model of the inverter switches are used.

I/O controller for controlling the sequencing of execution of I/O commands and for permitting modification of I/O controller operation by a host processor

Abstract: A data processing system which includes a host processor and an input/output (I/O) controller unit for controlling communication with I/O devices. The controller processor receives I/O commands from the host processor, accesses and stores control block lists of control commands associated with such I/O commands, and executes the control commands from such control block lists. The controller unit stores controller information concerning the operational capability of the controller unit and the host processor is capable of accessing such controller information and in turn can modify such operational capability if desired.

Photovoltaic system controller

Abstract: A photovoltaic system controller particularly adapted for utilization with a photovoltaic power system including a photovoltaic array, system battery, load and, optionally, an auxiliary generator. The controller utilizes a microprocessor to monitor various parameters of the system and to perform system control functions. The microprocessor is provided with a plurality of setpoints corresponding to desired system parameters for utilization as reference points for the conducting of control functions. The setpoints are adapted to be easily field adjustable to cover a wide range of parameters. The controller is particularly suited for adaption to an entire spectrum of system designs merely by replacing the programmable memory component of the controller. The controller derives its power from a tap off the system battery and is designed to withstand the harsh environment associated with remote site locations. All of the control functions are temperature compensated. The controller is provided with timing control means which allows the controller to be inactive between operating cycles so as to reduce power requirements.

Improvement in Arteral Oxygen Control Using Multiple-Model Adaptive Control Procedures

Abstract: A computer-based proportional-integral (PI) controller has been developed to control arterial oxygen levels in mechanically ventilated animals. Arterial oxygen saturation is monitored using a noninvasive oximeter and control is effected by adjusting the inspired oxygen fraction. The performance of the feedback system is sensitive to the open-loop gain so that the desired transient specifications can be achieved only by empirical adjustments of the PI controller. Because the open-loop gain includes the animal's response, it may vary with time and with the administration of positive end-expiratory pressure. Multiple-model adaptive control procedures were therefore used to desensitize the system to these variable gains. Computer simulations demonstrated the effectiveness of the algorithm over a wide variation of plant parameters. A comparison to a fixed, well-tuned proportional-integral controller showed an improvement in the regulatory response to a step disturbance. Animal experiments confirmed the feasibility of using multiple-model adaptive control to regulate arterial oxygen saturation.

Nonlinear Adaptive Attitude Control of Spacecraft

Abstract: A model reference adaptive control law is presented for largeangle rotational maneuvers of spacecraft using reaction jets. It isassumed that the various parameters of the spacecraft arecompletely unknown, and unknown but bounded disturbancetorques are acting on the spacecraft. The controller includes adynamic system in the feedback path. Simulation results arepresented to show that fast, large angle rotational maneuvers can beperformed using the adaptive controller in spite of uncertainty inthe system.

Uncertainty, Robustness and Sensitivity Reduction in the Design of Single Input Control Systems

Abstract: Feedback control of systems modelled as single input, time invariant, linear and continuous time systems is the subject of this thesis. A growing interest in the design of feedback control systems that can cope with model uncertainties has been the motivation for the study. Some commonly used design approches for various kinds of systems are investigated with respect to robustness properties.The Smith controller, often propsed to controlling open loop stable plants with an input delay, state feedback control based on linear quadratic optimization techniques and output feedback control using a Kalman filter are considered.Also some new design strategies are given. A graphical design philosphy suitable for open loop stable plants with no modelled input delay, feedback stabilization of systems with a known number of unstable poles and modification of the Kalman filter based controller are proposed. The objective in common for these control strategies is to obtain control systems with good robustness properties.

Control system for controlling the line pressure in a continuously variable transmission

Abstract: A pressure transducer, which senses clutch pressure and effects closed loop clutch control in a continuously variable transmission, is used after the clutch is fully engaged to provide closed loop line pressure control to a desired setpoint, which line pressure regulates the tension on the belt in the transmission. Only a single transducer is needed since there is a known relationship between the clutch and line pressures when the clutch is locked up. Prior to lockup, the line pressure is governed by an open loop controller which establishes the line pressure at a level higher than that called for by the setpoint. This ensures that the line pressure will be high enough to provide the required tension on the belt so that it will not slip. After the clutch is engaged, the closed loop line pressure controller (which includes both the open loop line pressure controller and the closed loop clutch controller) establishes the line pressure at the setpoint. For stable operation, the closed loop controller responds only to relatively slow changes of the setpoint. In response to fast changes, the closed loop controller is made ineffective so that the line pressure will be determined only by the open loop controller and will be greater than the level called for by the setpoint.

Attitude control of a spacecraft using an extended self-organizing fuzzy logic controller

Abstract: A simple method for extending the range of sensitivity of the self-organizing fuzzy logic controller (SOC) is proposed. The performance of the resulting controller is studied through its application to the attitude control of a flexible satellite. It is found that the extended SOC can provide excellent control and also possesses a high degree of robustness.

Control of a flexible robot arm with bounded input: Optimum step responses

Abstract: This paper studies the effectiveness of various controller design approaches on a flexible robot arm. The robot arm model used is that of Cannon-Schmitz flexible one-link robot. It is shown that the conventional PI controller cannot stabilize the closed-loop system. The idea of controller design using the stable factorization approach is explored. The controller design procedures, both with and without constraints on the actuator torque are discussed. The simulation results shows better system performance can be achieved by using these controllers instead of conventional LQG controller. The conclusion of this paper is that the stable factorizatlon approach has great potential in the area of flexible robot arm control.

Reliable fuzzy fault tolerant controller

Abstract: The invention is a controller which provides continuous regulation of the output of a process or a plant as well as performing discrete control functions. The REFFTAC includes an adaptive direct digital controller (ADDC) as a primary expert controller and a fuzzy expert controller (FECD) as a backup controller. In case of an error or failure of the primary ADDC the control function is transferred via an interface system (INF) to the FEC, thus preventing any fault in the REFFTAC mission. The INF system is a simple fuzzy controller which includes means to verify the control action and a timer to assure proper control action. It also includes a simulator that performs a self diagnosis on both the ADDC and the FEC to assure fault tolerance. Also, the REFFTAC comprises learning expert units which stores correct control actions for direct application to save time and to provide a reference for the INF system.

Process for open-loop and closed-loop control of a catalyst

Abstract: Process for metering the NH3 feed to a selective catalyst (1) for reduction of the nitrogen oxides (NOx) contained in the untreated emission of a two-stroke gas engine (M). In the process according to the invention at least 75 % of the NH3 requirement calculated from the power (N) and speed of rotation (n) of the engine (M) is fed to the catalyst (1), as a result of which rapid open-loop control of the NH3 feed is possible. The NH3 feed still lacking to make up the correct NH3 preset value is carried out by closed-loop control, the NOx concentration being measured in the exhaust gases and the NH3 feed being controlled in dependence on the NOx concentration determined.

Self-tuning process controller

Abstract: An industrial process control system in which an electronic controller acts in a controlled process subject to process "dead time" to maintain a process variable at a desired value. Applied as inputs to the controller are signals representing the process variable and a set point, the controller yielding an output signal that reflects the deviation of the process variable from the set point and acts to adjust a final control element in the system to cause the process variable to conform to the set point. To effect self-tuning of the controller, a microprocessor is provided which is responsive to the process variable signal and the output signal from the controller and functions while the controller is operating to identify in a discrete-time process model parameter-identifier the process dead time and the process parameters, and to compute tuned controller parameters, and to transfer the calculated controller parameters to the controller so that the controller can be tuned to prevailing process conditions.

Input and output peripheral controller cards for use in a programmable logic controller system

Abstract: The present invention is directed to a programmable logical controller (PLC) system incorporating a universal input controller card, a universal output controller card, and a symmetrical current mirror fuse blown detector circuit. The universal input controller card is capable of tracking input voltages from 12 to 240 volts, AC or DC. The universal output controller card is capable of outputting output voltages ranging from 12 to 120 volts, AC or DC with no significant leakage current and no load resistors. The current mirror fuse blown detector circuit detects blown fuses in each output channel of the output controller card.

Design of a lightweight robotic arm and controller

Abstract: This paper summarizes the design of an experimental lightweight robot arm and controller. It is a two-degree of freedom (dof) robot, driven by two electric motors and controlled by a control system based on three Intel 80286/80287 microprocessor/coprocessor pairs. Mechanical design considerations are discussed as well as the controller design. In addition, some preliminary modeling results are presented.

Optimized rotation-axis attitude maneuver controller for the Space Shuttle Orbiter

Abstract: This paper describes a controller for automatic attitude maneuvers of reaction-control-jet-equipped spacecraft. It is based on a new, real-time algorithm for solution of fuel-optimal maneuvers, assuming on-off control and linearized dynamics. These solutions provide efficient model trajectories that are easily tracked using a feed-forward, feedback controller structure. This approach was developed as a software upgrade to the Space Shuttle Orbiter on-orbit autopilot, for which it shows a very substantial performance benefit in a wide range of simulated maneuver tasks.

Diagnostic system for combustion controller

Abstract: A combustion control system includes a sensor assembly and a process controller, the sensor assembly including sensors for providing output signals indicative of process variables, the process controller responding to the output signals to maintain a desired operation of the process. The process controller continuously monitors parameters of the sensors and provides alarms whenever any of these parameters deviate from setpoint values, the process controller automatically prioritizing these alarms to provide a display of only the most relevant alarms. A housing enclosing the processor controller provides RFI/EMI shielding of the process controller including the attenuation and absorption of the EMI/RFI energy.

Orientation-dependant robot controller

Abstract: A joystick controller includes three gravity sensing switches, the outputs of which can be used in the assignment of joystick transducer outputs in six different ways depending on controller orientation. This permits intuitive control of a robot arm in that translational motions can always be effected by moving the joystick in the direction the arm is to move. Thus, a controller which is economical, reliable and intuitive multiplies the functions available from what is basically a two or three dimensional controller.

An auto-tuning controller

Abstract: An auto-tuning controller comprising: a controller for controlling a controlled system; a reasoning rule memory for storing a reasoning rule to be used for reasoning an optimum control parameter of said controller; and an adjustment section for adjusting said optimum control parameter of said controller by a fuzzy reasoning with the use of said reasoning rule.

lth-Step Lyapunov Min-Max Controllers: Stabilizing Discrete-Time Systems under Real Parameter Variations

Abstract: In this paper we are concerned with the stability robustness of discrete-time systems which experience real, structured, parameter variations The work is motivated by the notion of a "Lyapunov min-max controller" introduced by Corless [13] We generalize this concept and introduce lth-step Lyapunov min-max controllers With the help of these controllers we are able to identify a class of structured uncertainties, appropriately called "lth-step matched uncertainties" for which we can guarantee asymptotic stability These structures include the so-called "matched uncertainties" as a special case

An Adaptively Controlled Electrohydraulic Servo-Mechanism: Part 1: Adaptive Controller Design:

Abstract: A systematic model reference adaptive control design scheme is presented. The control scheme is developed and analysed within the framework of a sampled data system with a parameter adaptive algorithm designed on the basis of hyper stability theory. A number of supervisory functions are used to supplement the basic adaptive control system in order to enhance robust controller action.

New type of controller: the proportional integral minus delay controller

Abstract: In the design of a control system, the derivative controller is often required to obtain a quick response. However, when the control system is subject to noise inputs, the functioning of the derivative controller may be jeopardized owing to its sensitivity to high-frequency noise. In order to overcome this problem, a new type of controller, called the proportional-integral-minus-delay (PIMD) controller is proposed in this paper. It is shown that in addition to exhibiting almost the same characteristics as the conventional proportional-plus-integral-plus-derivative (PID) controller, the PIMD controller is less sensitive to high-frequency noise. It seems that an appropriate PIMD controller would be a good replacement for a PID controller. The output time responses of the closed-loop system with a PIMD controller and the frequency-response characteristics of a PIMD controller are obtained by computer simulation.

Correction to "Closed-Loop Regulation of a Physiological Parameter by an IPFM/SDC (Integral Pulse Frequency Modulated/Smith Delay Compensator) Controller"

Abstract: This theoretical paper discusses the realization of a discrete, closed-loop control system which uses an integral pulse frequency modulated/Smith delay compensator (IPFM/SDC) controller to regulate an in vivo physiological parameter to the prescribed quantity in real time. The pharmacokinetic (PK) plant considered is the sodium nitroprusside (SNP) blood-pressure plant. The simulated plant is appropriately time-and amplitude-scaled using op-amps and RC active filter elements.

Computer adjustable case handling machine

Abstract: A case handling machine including a programmable controller, i.e., a controller that includes a programmable CPU, for controlling the position of movable elements of the machine based on the size of cases to be handled is disclosed. The CPU is first programmed with the position of each movable element based on the size of each of the cases to be handled. Thereafter, when a box number related to the size of a particular case is inputted to the controller by an operator, the movable elements are automatically moved to the correct position. Since the movable elements are moved along interrelated axes, that could result in a conflict if the movable elements are moved in the wrong order, the controller program includes a subroutine that sets the sequence of axes movement such that conflicts are avoided. Further, movement of the movable machine elements is monitored as they are moved in a manner that senses jams, i.e., the inability of an element to move at the command of speed. In the event of a jam, element movement ends and a jam display is created. The controller uses low cost relay/motor drive systems and the controller program includes compensation for relay closure and motor up-to-speed time delays.

Laser control circuit for optical data recording/reproduction apparatus

Abstract: A laser controller for an optical data recording/reproducing apparatus includes a detector for detecting an intensity of a laser beam emitted from a laser, a servo controller for comparing the detected value with a reference value and generating a feedback signal in accordance with the difference between the two values, and a drive circuit for supplying a drive signal corresponding to the feedback signal to the laser, and a modulator for modulating the drive signal during recording. Furthermore, the laser controller includes a controller connected to the servo controller, a RAM, a timer, and a temperature sensor which are connected to the controller. When reproduction and erasing are to be performed, the operation of the modulator is stopped, and the drive signal is obtained by feedback control. When erasing is to be performed, a level of the feedback signal is stored in the RAM. When recording is to be performed, the operation of the servo controller is stopped, while the level of the stored feedback signal read out from the RAM is supplied to the drive circuit. As a result, the intensity of the laser beam is not controlled by feedback control, but by open loop control based on the readout feedback signal, while the intensity of the laser beam is modulated in accordance with the data to be recorded.

Adaptative control technique for a dynamic system

Abstract: A controller for a voice coil motor driven disk file actuator (10) is described. The device has an online adjustable gain characteristic for controlling movement of the actuator assembly and an estimator (56) that estimates actuator velocity and bias. Forward gain is estimated from position and coil current measurements and compared with a nominal value to create an error signal used to adjust the controller and estimator gain characteristics. The control technique allows changes in the open loop system without changing the closed loop performance. By monitoring loop gain it is possible to alter compensator gains to maintain a constant closed loop performance.

Controller Reduction: Concepts and Approaches

Abstract: This paper considers the problem of passing from a linear time-invariant high order controller designed for a linear time-invariant plant (of presumably high order) to a low order approximation of the controller. The approximation problem is often best posed as a frequency weighted L ? approximation problem. Many different controller representations are possible, giving different performance of the various reduction algorithms.

Optimal Level Controller for Steam Generators in Pressurized Water Reactors

Abstract: The authors consider the design of a suboptimal water-level controller for steam generators in large pressurized water reactors using linear output feedback control. A methodology for feasibility analysis and linear output feedback control design is developed through eigenvalue dynamics. The proposed controller is a linear, constant, partial state feedback law. The controlled system has the following desirable features: (a) the controller is independent of disturbance, (b) the water level returns to its prespecified level value following a step disturbance, (c) the controlled system is asymptotically stable, and (d) transient response is similar to the transient response of an optimal complete state feedback controller. An example illustrates the applicability and the effectiveness of the proposed techniques. >