Showing papers on "Open-loop controller published in 1977"

Process control system with backup process controller

Abstract: A process control system having a backup controller which is substituted for one of a plurality of primary process controllers upon the detection of a failure of one of the primary process controllers. The substitution of the backup controller is controlled by a backup director which is arranged to sense the operation of a primary process controller and to transfer the operating data from the failed controller into the backup controller to enable the backup controller to take over the operations being performed by the failed controller.

Automatic irrigation sprinkler system controller

Abstract: A solid state controller for an automatic irrigation sprinkler system is disclosed. Irrigation information is maintained in and acted upon by solid state logic and control circuit means. Initialization and re-parameterization of the irrigation information is accomplished with a keyboard input in conjunction with an alphanumeric display system indicating time of day, day of week, station number, run time associated with each station, and program type associated with each day of the week. A dual power supply is included being run normally from a commercial AC source to provide the proper voltage levels for both the logic and control circuitry and the sprinkler system station valves. Additionally, battery backup is provided. In the event of loss of AC power, the controller uses the battery to maintain only the real-time clock, turning off all other functions to conserve energy. Upon the resumption of AC power, normal operation is continued without loss of time continuity. The solid state controller disclosed contains features not possible with prior art mechanical type controllers.

Process control system with backup process controller

Abstract: A process control system having a plurality of process controllers each connected to a data highway to receive and send process control data is controlled by a backup director receiving input signals from each of the plurality of process controllers to sense the operability thereof. A backup controller is also connected to the data highway and has its highway address controlled by the backup director in response to a failure of one of the regular process controllers whereby the backup controller is directed by the backup director to assume the address of the failed controller. The data highway interface circuits of the failed controller are concurrently disabled whereby the backup controller provides a substitute for the full operation of the failed controller.

Programmable sequence controller with drum emulation and improved power-down power-up circuitry

Abstract: A programmable sequence controller is disclosed utilizing digital and analog inputs in order to generate digital output driver signals for the control of external systems or devices. The controller emulates mechanical sequence drums so that at any one time each of the simulated drums within the controller executes one of the addressable drum lines programmed within the drum. Each line of each simulated drum can be programmed to specify the energization or deenergization of any output driver as well as the energization or de-energization of any memory bit utilized by the controller in order to provide communication between drums. Each drum may also be programmed to have one or two sets of exit conditions, which if met, cause the controller to effectively rotate the drum to a specified drum line and execute this new drum line during the next scan of the controller. The controller can also sense emergency conditions and cause any or all of the drums to rotate to a specified line regardless of the drum line then being executed by the controller for each of the drums. An improved power-down, power-up circuitry insures an ordered and complete shutdown of the controller if any of a number of conditions exist, including utility AC failure and impending failure of several of the power supply voltages. Handshaking circuitry between the power supply and the remainder of the controller insures that the controller maintains memory validity for all types of shutdown situations, including momentary losses of any supply voltage. The programmable sequence controller includes a clock-calendar capable of continued operation during periods of extended power outages. The clock-calendar can be utilized in any drum line to form part of the control scheme. All programming of the simulated drum lines is performed through an interconnected data communication device such as a teletypewriter and utilizes a simple user-oriented language, with monitoring and diagnostic capability to facilitate debugging.

Electro-hydraulic governor employing duplex digital controller system

Abstract: An electro-hydraulic governer employing a duplex digital controller system for the optimum speed control of a steam turbine running with increasing speed in the starting stage or under load. Each of the digital controllers is operable with both a control mode and a stand-by mode, and when one of the digital controllers is placed in the control mode for controlling the rotating speed of the turbine, the other is placed in the stand-by mode to prepare for possible failure of the controller operating with the control mode. A failure detecting unit detects failure of the digital controller operating with the control mode. An output switching unit disconnects the faulty digital controller from the control system and switches over the operating mode of the stand-by digital controller from the stand-by mode to the control mode for the continuous control of the rotating speed of the turbine. A display is provided on an operator's console to display the outputs of these two digital controllers, and the faulty digital controller is detected by non-coincidence of the displayed information. The faulty digital controller having been disconnected from the control system by the output switching unit is repaired as quickly as possible, and after necessary repair, it stands by to prepare for possible failure of the other controller operating with the control mode.

Open-loop electric drive with corrective controller

Abstract: A controller minimizes periodic torque or force perturbations in an inductor-type synchronous motor drive by supplying current waveforms to each motor phase that contain a fundamental frequency component and selected harmonic components. The harmonic components in the phase currents heterodyne with the periodic permanent magnet flux fundamental frequency to create periodic torques or forces which subtract from the unwanted torques or forces perturbing the moving portion of the motor. The controller, which includes an interpolator, a memory, and a converter, provides for smooth incremental movement of a member such as a plot head, at substantially constant velocity, by applying selected continuous periodic waveform signals as phase currents to the windings of inductor-type synchronous motors.

Secondary storage facility with serial transfer of control messages

Abstract: A drive for a secondary storage facility that includes a controller and a drive bus that interconnects the controller and drive. Data is transferred between the drive and controller in serial fashion over a read/write data line. Control information, in the form of control messages, is transferred between the drive and the controller in serial fashion over two message lines of the drive bus. A message transfer is initiated by a strobing pulse from the controller and is controlled in response to clocking signals from the controller. During a transfer of a message to the drive, a controller-to-drive signal is asserted and conveyed to the drive. When the message has been completed, the controller-to-drive signal shifts to a non-asserted state and enables the drive to transmit back to the controller a status message under the control of clocking signals generated in the drive in response to the clocking signals from the controller that are returned to the controller over the strobing signal line.

Data communications system for a reproduction machine having a master and secondary controllers

Abstract: A data communications system for an electrophotographic type reproduction machine or copier. The system includes a programmable master controller with memory and a command byte generator. A plurality of secondary controllers provide input data bytes reflecting the machine status to the master controller and receive command bytes from the master controller for operating the machine components. The secondary controllers are each connected to the master controller such that corresponding data bits of the secondary controller are ORed together to provide simultaneous transmission of input data bytes from the secondary controllers to the master controller while assuring that corresponding bits of the simultaneously transmitted bytes have mutually exclusive data therein.

Multiple control circuit with floating setpoint

Abstract: A process control system providing a particular control effort function is divided into a primary control effort portion having a primary controller, and a feed back from the controlled process to the primary controller, and a secondary control effort portion having a secondary controller in controlling relation therewith, and receiving its control input from the primary controller. The secondary controller is provided with limits such that it becomes saturated in operation, thereby permitting selective overriding by the primary controller, while utilizing the secondary controller and actuators the maximum practical amount. The arrangement is suitable for use with continuously variable devices or for use with on-off (bang-bang) devices. The particular embodiments illustrated are (1) a bang-bang heater system, and (2) a continuously variable fluid flow control system.

Programmable controller with limit detection

Abstract: of the Disclosure A programmable controller for sensing the status of sensing devices and controlling the state of oper-ating devices in accordance with a stored program includes a position encoder input module which receives position data. In response to instructions in the stored program, the position data from the input module is compared with an upper and a lower limit stored in the controller memory, and if the data lies outside the limits, the controller logic unit is forced to a false decision.

A dual-loop model of the human controller

Abstract: A representative model of the human controller in single-axis compensatory tracking tasks that exhibits an internal feedback loop which is not evident in single-loop models now in common use is presented. This hypothetical inner-loop involves a neuromuscular command signal derived from the time rate of change of controlled element output which is due to control activity. It is not contended that the single-loop human controller models now in use are incorrect, but that they contain an implicit but important internal loop closure, which, if explicitly considered, can account for a good deal of the adaptive nature of the human controller in a systematic manner.

Central computer controller for multiterminal HVDC transmission systems

Abstract: The operating requirements of a central digital computer controller for a multiterminal parallel connected HVdc system are developed using an ac/dc system simulator connected in real-time to a minicomputer. Control of dc system power for steady-state, faulted, dynamic and transient conditions is investigated for typical telecommunication delays with both open and closed-loop central controllers. Open-loop control is advantageous when fast change of dc power is required while closed-loop control is preferable for steady-state and dynamic control during slower disturbances. Acceptable calculation delay times can be achieved with existing minicomputers. The computer provides increased operating flexibility, data storage and calculation capability compared with hardwired controllers.

Testre for electronic controller of automobile

Abstract: PURPOSE: To provide a tester for an electronic controller of an automobile which can test and judge whether internal logics of the controller are right or not and portions of the controller out of order while the controller is held carried on an automobile by constituting the tester such that it is provided with a main storage memory for simulation and test programs and also with a central processing unit. COPYRIGHT: (C)1979,JPO&Japio

Adaptive pole placement for linear stochastic systems with unknown parameters

Abstract: The control of single-input single-output stochastic systems with unknown parameters is discussed. We consider first the stochastic pole placement strategy and highlight some of its properties. It is shown that the desired controller can be obtained by solving a linear polynomial equation. In addition, we show that for any stochastic pole placement problem there exists, under suitable conditions, an equivalent problem where the open-loop system is a "least-squares" model. Three approaches to the adaptive control problem are proposed: the identification control (IC), the least-squares identification/control (LSIC) and the control parameter estimation (CPE) methods. A computational example is given.

Optimal stochastic path control of surface ships in shallow water

Abstract: The control of a surface ship along a prescribed straight-line path is formulated as a stationary, linear, state-variable control problem. The open-loop characteristics of this problem are studied using data for a Mariner type ship at two speeds and varying water depth-to-draft ratio and for the tanker Tokyo Maru at one speed and varying water depth-to-draft ratio using data obtained by Fujino. Optimal stochastic control systems using a Kalman-Bucy filter and a state-feedback controller are designed for both vessels at various conditions. These designs are developed to control the ship when subject to random, zero-mean disturbances. The design disturbances are the yaw moment and sway force due to a passing ship which are modeled by first-order shaping filters in the design derivation. System performance is studied by the evaluation of the Root Mean Square (RMS) response of the controlled ship to the modeled design disturbances and by digital computer simulation of the response of the controlled ship to initial condition errors and the specific disturbances due to a passing ship. The effects of vessel speed and water depth on the design and performance of these controllers are studied in detail. These results yield guidance for the selection of design conditions for the design of constant-gain controllers and provide an assessment of the need for adaptive controllers which can adjust the gains to remain optimal as the ship characteristics change with vessel speed and water depth.

Closed loop performance of induction motors with constant volts/hertz control

Abstract: Characteristics of a closed loop induction motor drive, supplied from a variable frequency voltage source, and operating under constant volts/hertz control are presented. The motor linearized equations in the synchronously rotating reference frame are used to analyse the drive dynamic performance. It is shown that this performance can be greatly improved by including a properly designed speed controller in the drive structure. Thus, the decrease in stability, associated with the open loop motor operation is eliminated and the resulting drive gives satisfactory performance over the entire input frequency range. The experimental results, which confirm the validity of the motor dynamic model are also included.

A precision temperature controller

Abstract: A description is given of a fully electronic precision temperature controller. Its construction, properties and operation are described. The temperature setting of the controller is directly calibrated in the temperature range -200 to +500 degrees C using a platinum resistance thermometer. The temperature resolution of the controller amplifier is better than 2*10-5 degrees C and temperature stability of the controller components is better than 10-4 degrees C per 1 degrees C change in external temperature. The typical precision realized with the controller is about 10-4 degrees C. The design of the controller resistance bridge makes the controller a versatile device. It can be used as either a constant-temperature controller, a differential-temperature controller, a temperature programmer with a linearized sensitivity of 1 Omega degrees C-1 over -200 to +500 degrees C or a simplified transfer function analyser of thermal systems.

Design of optimal machine-control systems

Abstract: A method is described for the design of optimal linear servomechanisms. The system to be controlled is assumed to be linear, time invariant and multivariable. The cost function to be minimised is quadratic and is measured over an infinite time interval. Expressions are given to enable the optimal controllers for both open-loop and closed-loop systems to be calculated. A result is obtained that allows the cost function weighting terms to be related to the optimal-compensated system pole positions, and hence to the system transient response. The relationship can be used when choosing the weighting constants. The design procedure is illustrated in the design of a controller for a strip processing line for which the tension in the strip and the speed of the drives is to be controlled. A new method of spectral factorisation is also introduced. This can only be used on a restricted-class matrices having a degree of symmetry; however, it is much easier to use than previous methods.

A microprocessor stepping-motor controller

Abstract: A new concept for digital computer control of multiple stepping motors which operate in a severe electromagnetic pulse environment is presented. The motors position mirrors in the beam-alignment system of a 100-kJ CO2 laser. An asynchronous communications channel of a computer is used to send coded messages, containing the motor address and stepping-command information, to the stepping-motor controller in a bit serial format over a fiber-optics communications link. The addressed controller responds by transmitting to the computer its address and other motor information, thus confirming the received message. Each controller is capable of controlling three stepping motors. The controller contains the fiber-optics interface, a microprocessor, and the stepping-motor driver circuits. The microprocessor program, which resides in an EPROM, decodes the received messages, transmits responses, performs the stepping-motor sequence logic, maintains motor-position information, and monitors the motor's reference switch. For multiple stepping-motor application, the controllers are connected in a daisy chain providing control of many motors from one asynchronous communications channel of the computer.

Mode indication system

Abstract: A cabin pressure control system has two independent controllers, one of which is the primary controller and the other the standby controller taking control in case of primary controller malfunction. The controllers switch roles automatically each flight. An annunciating system indicates the identity of the primary controller on the previous flight and maintains the designation in case of malfunction so that a defective unit may be readily identified.

Input Matching: A New Procedure For Adaptive Control Design

Abstract: Adaptive input matching, based on directly adapt- ing controller parameters to form a control effort matching a desired input, bypasses the identifiability constraints of indirect adaptive control and the per- fect matching limitations of current direct adaptive exact output/model matching schemes. This original concept allows combination of stable parameter adjust ment algorithms and optimal performance considerations. Furthermore, the focus on input matchability allows consistent control despite inconsistent control parame- ter identification. Examination of three diverse plant objective classes demonstrates the immediate broad ap- plicability of the input matching concept and provides several suggestions for further application of this new procedure for adaptive control design.

Electronic speed control unit for wire drawing machine - which synchronises speeds of machine and coiling drum

Abstract: Speed control circuit for a machine, esp. a wire drawing machine uses a motor (M1) driven at speed (S1), from which the wire travels onto and off a coiling drum using a motor (M2) driven at speeds (S2). A specified speed (S1s) for motor (M1) is fed via a run-up transmitter to a master controller (C1). A second controller (C2) is fed with a specified speed (S2s) for motor (M2), and also with the actual speed (S2a) for motor (M2); and the difference between S2s and S2a is fed to controller (C1) to adjust the speed of motor (m1). Controller (C2) may be connected to the run-up transmitter, or directly to controller (C1). Synchronises the speed of the two motors so that e.g. the drum does not travel at an excessive speed before it receives the wire.

Design aid for approximate p.d. and p.i.d. on/off controllers

Abstract: The graphical construction given aids controller design and the understanding of the controller mechanism.