Abstract: A real time adaptive control capable of maintaining stable operation with changing inertia. The controller utilizes a pseudo-derivative feedback (PDF) type control wherein dynamic adjustment is achieved by adjusting only a single variable. The variable can be controlled as a function of the derivation of motor speed divided by motor current for adaptive control with changing inertia. Control may also be achieved as a function of motor speed divided by the integral of motor current over the same interval. In a digital implementation the integral of motor current the time required for a predetermined speed change provides effective control.

Abstract: A pair of quantized duty ratio proportional-integral-differential (PID) converters are coupled to provide power sharing to a load. One of the converters is a master and the other is a slave, and a PID controller is coupled to both of the converters. The PID controller also supplies two digital offset signals to the converters during normal operation, which insures load sharing by control of the duty ratio of the converters. If one of the converters fails, a sensor control unit switches control to the other unit and the digital offset signal goes to zero.

Abstract: A dual setpoint controller system comprising first (24) and second (26) setpoint controllers. Each setpoint controller comprises a target counter (30, 80) for storing a digital target value, control elements (38, 40, 88, 90) for enabling an operator to control the target value, a setpoint counter (32, 82) for storing a digital setpoint value, and comparison means (42, 44, 92, 94) operative when the setpoint value is not equal to the target value for causing the setpoint value to change at a selected rate towards the target value. Each target value is displayed via a display device (34, 84), and a digital-to-analog converter (36, 86) is provided for converting each setpoint value to an analog signal.

Abstract: A variable speed integrator for controlling the response time of a valve which regulates the amount of coolant flowing to a heat exchanger so as to control the temperature of the cooled substance output from the exchanger. The temperature of the cooled substance is sensed and compared to a set point temperature to determine an error temperature representing the difference between the sensed and set point temperatures. The error temperature is integrated by the variable speed integrator, the output of which is used to drive the valve into position. The control system monitors the rate of change of the sensed temperature to determine a low system gain. When the rate of temperature change indicates a low gain system, the gain of the integrator is increased to decrease the response time of the valve.

Abstract: Method and apparatus for self-tuning a Proportional Integral-Derivative controller for controlling at least one load characteristic to a predetermined setpoint from calculated values of Proportional Band (PB), Integral Time Constant (ITC) and Derivative Time Constant (DTC) by application of power to the load, establishing a cut-off point to remove power to the load, determining the slope of a measured value of the at least one load characteristic and starting an integral time counter upon detection of the power cut-off point, determining at least one value X.sub.min at which the value of the measured value decreases by a fixed percentage, determining the maximum value X.sub.max of the at least one load characteristic, calculating the values of the PB, ITC and DTC by determining the rise X.sub.r =X.sub.max -X.sub.min and determining PB and ITC from a stored table relating X.sub.

Abstract: The process control apparatus according to the present invention is adapted to control the process automatically in compliance with the state of the process characteristics. In the process control apparatus, when the process characteristics are found to be in a steady state, the control is performed by a first process control operational means suited for sample controlling the process according to the control constants for the first process control operational means as determined during the control of a second process control operational means, while, when the process characteristics vary frequently, the control is performed by the second process control operational means which is suited from sample controlling the process.

Abstract: A discrete proportional-integral-differential controller, driven from a sampling digital error amplifier, is used to penetrate a quantized duty ratio control signal to provide dynamic output voltage regulation for switching dc-to-dc power converters. The sampling frequency of the digital PID controller is equal to the switching frequency of the power converter, so the digital controller may be used at different switching frequencies without recompensation. Digital techniques are also used to provide output current limiting, soft-start, undervoltage lockout, overvoltage shutdown, and power master-clear indications.

Abstract: A motor speed control device for variably controlling the rotation speed of a motor over a wide range. The control device performs proportional integration (PI) using an actual motor speed and a set motor speed and applies the resulting amount of operation to a pulse wave modulator, thereby feedback controlling the motor rotation. A constant assigned to a speed compute section is variable to finely adjust the motor speed. A plurality of proporational gains K.sub.p and a plurality of integral gains are selected one at a time each according to the set motor speed. The PI operation, selection of a constant and speed computation are performed inside of a single CPU.

Abstract: A position control system having dual controllers, each capable of operating in either a proportional or a proportional plus integral gain mode, is normally operated with one controller in the proportional plus integral mode and the other in the proportional mode, each controller contributing its proportionate part of the output position control signal to the position controlled device, and each controller capable of operating alone in the proportional plus integral mode in the event of a failure.

Abstract: A multiplex control system including a plurality of controllers, the main controller being arranged by hardware, while the subsidiary controller being accomplished by software. Each of the controllers has a PID operator for calculating the proportional, differential and integral components of process data, and the difference of the integral components of both PID operators is processed through a first-order time lag operator and the result is used to correct the error of the output from the PID operator of the subsidiary controller. In the occurrence of abnormality, control of the control object is switched from the main controller to the subsidiary controller using the first-order time lag element attached to the switch unit thereby preventing the tracking of control data.

Abstract: A PID controlling meter is provided with unit for displaying an amount of operation representing the sum total of the bias constant and the operation result of three terms, i.e., a proportional term, an integrating term and differentiating term each of which is a function of deviation. The meter also has a constant setting unit for setting displayed amount of operation as a control parameter; unit for displaying set values of the constant setting a unit; a unit for reading the set values of the constant setting unit when a power source is closed; and a unit for determining bias constant when the power source is closed on the basis of the constant set values read by the reading unit.

Abstract: A process control apparatus wherein dynamic characteristics of a process are identified in accordance with process inputs and outputs, so as to tune digital PID (Proportional-Integral-Derivative) parameters in accordance with the identified dynamic characteristics. The process is an N-input/output process having an interference between the process inputs and outputs. Each transfer function between a given process input and process output is identified. A transfer function between a set-point signal and the process output is obtained and matched with that of an N-input/output decoupled reference model, to tune the PID parameters.

Abstract: In tuning a regulator (2) of the PID-type of a process (1) in a feed back system where the process and the regulator has a transfer function G(s) in common, a method is proposed for bringing the system into self oscillation for measuring the amplitude and frequency of the oscillation and tuning the regulator in dependence of the measurements obtained. A circuit function (NL) having non-linear characteristic and a describing function N(A) is introduced into the system in series to the process for acting on the regulator signal (e). Self oscillation is obtained if G(i.omega.).multidot.N(A)=-1 for at least one value of the angular frequency .omega. and the amplitude A of the regulator signal (e). An apparatus for performing the method is disclosed.

Abstract: In a circuit arrangement for an alternating control a PI controller comprises a first operational amplifier having an output connected via a resistor to the non-inverting input of a second operational amplifier wired as an impedance transformer. The output of the second operational amplifier is fed back via an RC stage to the inverting input of the first operational amplifier. The output of a second controller is connected via a decoupling diode to a junction between the decoupling resistor and the non-inverting input of the second operational amplifier. Positive as well as negative signals can occur at the output of the first operational amplifier, and discontinuities in control during a switch over between the two controllers are avoided.

Abstract: A digital PID process control apparatus is proposed wherein dynamic characteristics of the process are identified by supplying a persistently exciting signal to a closed-loop control system, and the persistently exciting signal is not supplied to the system after identification is completed, thereby tuning PID control parameters in accordance with the identified pulse transfer function. The control apparatus has a detector for detecting model error of the process in operation, a pulse generator for superposing a pulse signal on a set-point signal to the process when the model error is detected, a calculator for detecting a transient change in the model error when the input signal to the process changes in a pulse form, and a restart circuit for restarting generation of the persistently exciting signal when a change in the model error is detected, and for restarting an identification/tuning function.

Abstract: Apparatus, for use in a servo-control system and which provides a smooth "bumpless" transition while switching from one transducer feedback signal to another, is described. Specifically, with this apparatus, a plurality of tracking signals are first produced in which each signal has a value which, in response to the value of a corresponding select signal, either tracks the feedback signal produced by a corresponding one of a plurality of transducers or remains constant. Each of these tracking signals is then subtractively summed with the feedback signal produced by the corresponding transducer in order to produce an output signal. Each of the output signals is then fed-back and subtractively summed with a command signal and the resulting difference, in turn, is applied as an error signal to a servo-amplifier. The values of all the select signals are set, by illustratively a process computer, in accordance with the particular transducers being switched.

Abstract: A regulating device for an electromagnetic control element, especially for an internal combustion engine with auto-ignition, is proposed in which a non-linear regulator with preferably a PD characteristic is coupled with a pulse regulator, preferably a two-point regulator with PID characteristic. Of special advantage is the interposition of a limiting device, which allows an increase in the D portion of the non-linear regulator, while at the same time suppressing interference. This results in an excellent control behavoir, especially in the face of small control deviations and in a control element or control circuit afflicted with friction and/or (magnetic) hysteresis.

Abstract: A process control apparatus is provided which has a PID controller to which is supplied a sampled signal of a control deviation signal of a process value signal and a reference signal and which generates a PID control signal according to sampled-value PID control constants. A non-linear controller is connected in parallel with the PID controller. A sum signal of the output signals from the PID controller and the non-linear controller is supplied to a process through a holding circuit. The process control apparatus further includes a circuit for identifying the dynamic characteristic of the process according to the sum signal and the sampled signal of the process value, and a circuit for calculating a transfer function of the process in the Laplace operator domain and for determining the sampled-value PID constants of the PID controller according to the dynamic characteristic.

Abstract: In a P-I-D process control where a process variable is controlled employing the three mode equation:Output=K.sub.1 E+K.sub.2 .intg.Edt+K.sub.3 (dE/dt)the sign of the derivative is compared with the sign of the error. If the derivative and error signs are unlike then the derivative term is discarded. Discarding the derivative term when its sign is unlike that of the error E, prevents the derivative opposing the return of the process variable towards the desired value or "set point.

Abstract: A microprocessor based single loop control instrument is described which can operate as any one of several different types of controllers, each of which can provide two or more different modes of operation. The control instrument comprises a microprocessor, a read only memory in which is stored the operating program for the control instrument, means for causing the control instrument to operate as one of the types of controllers provided for by a program stored in the read only memory and means for selecting the mode of operation of the controller. Further, in accordance with the invention, the control instrument is supplied with a control panel controlled by a second microprocessor and connected to the first microprocessor by a communication bus. The second microprocessor controls a bar graph display for displaying at least one signal related to the operation of the control instrument as well as means for selecting the signal that is displayed.

Abstract: The method serves to control sluggishly reacting plants by controllers in which rapid changes in set value occur. The controller has an integral section and a proportional section separate from the I-section. The I-section receives a control deviation signal formed from the actual value and the set value, whereas the P-section is supplied with the set value. The output signals of the I-section and of the P-section act on the plant. The I-section is blocked for the duration of an abrupt change in the set value.As a result of this relatively short interruption in operation of the I-section, the control of the plant is improved.

Abstract: An airplane braking system includes a torque control circuit for control torque developed in a braked landing wheel. The torque control circuit is responsive to a torque signal from a transducer located in the torque equalizing links of the landing gear assembly. The torque signal is compared with a reference signal and passed through an integrator, a differentiator and proportional gain amplifier in the torque control circuit to provide a torque control signal. The torque control signal is applied to a brake pressure relief valve to reduce brake pressure. The torque control circuit is advantageously integrated with an antiskid circuit responsive to wheel speed to thereby preventskidding as well as excessive torque conditions.

Abstract: The PI controller for a blockable servo motor comprises a selector having a first, normal operating position in which a difference signal is fed to the I network. In the other position, the output of a subtraction member is fed to the I network. The inputs of the subtraction member receive the input and output of the servo motor. The selector is actuated by means of a comparator which also blocks the servo motor when the difference signal is of small absolute value. In this way, the servo motor is not operated as frequently and yet this does not appreciably impair the control accuracy.

Abstract: A control system for controlling the variables of a process, comprising at least two proportional-integral-differential controllers each comprising a linear signal path, a differentiating signal path and an integrating signal path, all connected to an input junction. The outputs of the linear signal path and the differentiating signal path are added at an intermediate junction and the resulting sum signal is added to the output signal of the integrating signal path at an output junction. Each proportional-integral-differential controller supplies an output suitable for controlling one of the process variables such that this process variable is maintained as close as possible to a predetermined maximum value without any of the other process variables exceeding its respective predetermined maximum value.

Abstract: There is disclosed a method and an apparatus for the incorporation of varying flow in the control of process quantities. According to the invention the passing flow is measured and the amount of material flowed through the process is determined by integration of the result of said measurement. Furthermore, values of a variable are determined in direct ratio to the amount of material and the control of the process is performed synchronously with regard to that variable.

Abstract: A process control system is provided in which a process variable is compared to a set point for the process variable by a process controller with the results of the comparison being utilized to control the process in such a manner that the process variable will be substantially equal to the set point for the process variable. A critically damped response of the process variable to a change in the set point is achieved by utilizing a process controller which has the characteristics of a proportional-integral-derivative controller followed by a first order lag. Tuning of the process controller is accomplished by changing a time constant which is common to the proportional, integral and derivative terms of the proportional-integral-derivative controller and also common to the first order lag.

Abstract: There is provided a motor control system adapted for use, for example, with a sample analyzer, having means for generating signals representative of motor movement, and a logic circuit for analyzing the motor movement signals to determine increments of movement and the direction of movement. Digital circuitry is also provided for tracking the actual motor position as it is moved in either a forward or reverse direction, and comparing the tracked position with a programmed destination position. When and only when the motor is within a predetermined range of the destination position is a variable control generated, causing braking of the motor so that it stops exactly at the programmed destination position.

Abstract: An antiskid brake control system responsive to a periodically posted wheel signal operates to generate and store a modulator control signal and a transient control signal. The control system then waits until a new value of the wheel signal is posted, and then promptly generates a lead signal as a function of the new value. This lead signal is then promptly combined with the stored modulator and transient control signals to produce a composite brake control signal. In this way the time delay between the posting of a new value of the wheel signal and the generation of a new lead signal and composite signal is minimized.

Abstract: The present invention relates to an automatic steering apparatus for ships which prevents the occurrence of directional instability due to unusual phenomena which occur at small rudder angles of so-called full-bodied ships.When the rudder angle of such ship is small, two stable steady turning conditions occur so that the turning movement cannot assume any single state and it results in a frequent and irregular unstable ship motion.

Abstract: A proportional control system for controlling a condition at a setpoint is disclosed wherein the system has reset for substantially reducing system droop and incorporates reset windup limiting, the system having a setpoint apparatus for establishing the setpoint for the system, a feedback circuit for supplying a feedback signal in accordance with the condition, a reset circuit connected to both the setpoint apparatus and the feedback circuit for substantially reducing system droop, the reset circuit for supplying a reset output signal, and the reset circuit having a reset windup limiting circuit for limiting reset windup of the reset circuit.

Abstract: There is provided a process control system having a deviation circuit for calculating a deviation of the process variable representing a state of a process to be controlled from the set-point value. And there is provided a process control system further including a differential circuit for differentiating a deviation, a controller for estimating a trend of a process on the basis of the two pieces of information and determining a proper controlling amount of the process variable in accordance with the process trend estimated.

Abstract: In a control method wherein a control signal is generated in response to the deviation of a process variable signal from a setpoint signal and the time integral over this deviation, the windup of the respective controller is prevented by automatically modifying this deviation by a signal representative of the difference between the control signal and the process control signal such as to reduce the deviation of the process variable signal from the setpoint signal by an amount representative of the difference mentioned.

Abstract: The specification discloses a novel method for controlling production processes of a pneumatic, electrical or hydraulic nature and apparatus therefor. The method, and therefore the apparatus for performing said method, counteracts any process change by utilizing the error difference and the rate of change of the error difference between a feedback signal related to a current condition of the process and a desired value related to the desired condition of the process.The error difference and rate of change and then utilized to produce a correction signal which is adapted to remain unchanged as long as the process being controlled, and the desired value signal, both remain in static condition, but which also has a unique look ahead feature such that said correction signal attempts to become saturated as soon as a new desired value is supplied, or a process change occurs.

Abstract: An override control system is provided in which the integral mode of the controllers not selected is forced to track the integral mode of the selected controller to prevent windup of the controllers not selected. Selection of the active controller is based only on the proportional mode for proportional-integral controllers. Selection of the active controller is based only on the proportional mode and the derivative mode for proportional-integral-derivative controllers.

Abstract: A controller for process control has an adaptive gain. The controller is used as part of a closed feedback loop, and will, in response to different variables, maintain a constant loop gain regardless of non-linearities in the system.Signals representing the variables are transformed into corresponding active gain factors. The active gain of the controller is computed as a function of the product of the active gain factors and then translated to an output signal. One or more active gain factor is defined as having a first gain factor, at least one breakpoint, and a second gain factor. If two breakpoints are used, a base gain is interposed. Furthermore, one or more variables may have a step function as an active gain factor.

Abstract: A method and apparatus for adjusting a variable parameter of a dynamic system in response to a signal representative of the system performance so as to optimize system performance with respect to that parameter. A first signal related to system performance is extracted from the dynamic system and is thereafter coupled to a plurality of performance index blocks, each of these blocks for operating on this signal according to a different predetermined characteristic transfer function. The output level from a selected performance index block is periodically sampled and the sampled level is compared with a previously sampled level to provide a positive or negative difference signal. A first pulsed signal is formed wherein pulses and zero levels are respectively representative of the incidence of opposite polarity levels in the difference signal.

Abstract: A control method is described in which, a plant, a reference model and a corrector are serially connected in the loop. The plant output is fed back and compared against a reference signal to develop an error signal. The reference mode operates upon the error signal with a predetermined transfer function to develop signals proportional to the error signal and various successive order derivatives of the error signal. The model output signals are applied to a corrector circuit which multiplies the respective model output signals by appropriate coefficients, and sums the resultant product signals to produce control signals for the plant. Provisions are also disclosed for varying the coefficients to provide self-adaptive control. Provisions for accommodating process delays are also provided.

Abstract: A Batch Option Module is provided for a process control instrument. Whenever the process control instrument reaches the limits of its control range, the Batch Option Module is activated to limit the output of the instrument as a function of the process variable, the setpoint, and an adjustable bias. When the output of the instrument due to normal control action no longer trys to exceed the Batch Option Module limit, the Batch Option Module is deactivated.

Abstract: A controller for controlling a controlled system in connection with detecting means which detects the output of the controlled system and feedbacks a corresponding detected signal to the controller. The controller comprises proportional amplifying means for amplifying the error between a reference input signal and the detected signal, proportional and/or integral amplifying means for proportionally amplifying and/or integrating the error between the output of the proportional amplifying means and another signal to provide the resulting output as manipulating signal to the controlled system and derivative amplifying means for differentiating and amplifying the detected signal to provide the resulting output as the other input signal to the proportional and/or integral amplifying means whereby the controlled system is controlled in an overshooting-free mode.

Abstract: A control device for turbines with speed and load control, in which the load control includes an integrator with or without an output value limiter. The speed control and the load control are functionally independent of each other over the entire working range. The speed control likewise includes an integrator, and the outputs of the two controls are conveyed to a MIN-member as input signals while the smaller input becomes the output signal of the MIN-member and takes over the positioning of the turbine inlet valve.

Abstract: A redundant channel control system includes one or more voters having a high-pass filter connected between a pair of voter inputs.

Abstract: A process controller which has at least a derivative control mode includes a comparison amplifier wherein a measured variable signal is compared with a set-point signal to produce an error signal. An auxiliary control circuit including a signal level change detector is connected to detect changes in the set-point signal. During intervals of constant set-point signal, the primary control circuit operates normally. Upon the occurrence of a change in the set-point signal, the change is detected by the auxiliary control circuit and produces an auxiliary control signal which is applied to momentarily inhibit the operation of the derivative control function of the controller.

Abstract: An automatic control system wherein repetitive pulses, the frequency of which is responsive to a remote condition, such as prime mover RPM, are converted to a DC voltage level. The voltage level is compared to a reference by a difference amplifier to produce an error signal. Further signals are produced from the error signal, including an integral thereof, which signals are ultimately used to control the remote condition. The integrator is provided with an offset circuit to prevent saturation thereof during override of the normal control signal by an external limit signal as, for example, excessive engine temperature or smoke output.

Abstract: An automatic control system wherein repetitive pulses, the frequency of which is responsive to a remote condition such as prime mover RPM, are converted to a D.C. voltage level which is then compared to a reference to produce an error signal. Three further signals are then produced, one proportional to the error signal, one proportional to its integral and the other proportional to its derivative. The three further signals are summed and amplified to the extent necessary and the resultant used to control an element which in turn controls the remote condition. Included is a fail safe circuit effective to cause the remote condition controlling element to shut off in the event incoming pulses are not present. Provision is made whereby the system may respond to the summed signals described above or an external signal which may be derived from a function generator or a limiting value established by an external condition.

Abstract: The regulator having a P-member and an I-member uses a timing means to delay the desired value signal prior to subtraction of the delayed signal from the received actual value signal. The resultant signal is then delivered to the I-member. A further P-member is also used to receive the desired value signal and to deliver the signal for addition to the superimposed signals from the first-named P-member and I-member in order to produce a load-control signal.

Abstract: A servosystem is comprised of an energy-storing controlled system having an output variable which is to be maintained at a predetermined value. An energy-varying unit, for example a source of electrical energy, is connected to the controlled system for energizing the latter. Alternatively, the energy-varying unit could be operative for removing energy from the controlled system. A two-mode control unit is operative in the first mode thereof for causing the energy-varying unit to effect a change in the energy stored by the controlled system, and is operative in the second mode thereof for preventing the energy-varying unit from effecting such change. An error-indicating unit is operative for generating an error signal indicative of the deviation of the output variable of the controlled system from the predetermined value to be maintained.

Abstract: Control of a process in response to a process signal which is incrementally altered at periodic intervals is accomplished by performing a simulated differentiation of the process signal prior to use of the process signal as an input to a process controller.

Abstract: A removable control signal is provided which varies as the product of a gain constant times the control error and has means for increasing the gain constant as a time integral of the error. The integral is reset to zero, thus making the gain constant zero, when the error crosses zero to avoid an excessive build-up of the value of the control signal as when the error fails to promptly correct itself.

Abstract: Three-axis attitude control of a substantially zero momentum satellite is achieved by a control system which includes three mutually orthogonal reaction wheels and a fourth backup reaction wheel. The backup wheel is mounted on an axis which is skewed with respect to the axes of the three mutually perpendicular wheels. Spacecraft attitude is normally maintained by torques developed by the mutually orthogonal wheels. If one and only one of the orthogonal wheels should fail to correct the attitude error on its associated axis, the backup wheel is caused to rotate and develop a torque to maintain spacecraft attitude.

Abstract: An attitude control system for a substantially zero momentum spacecraft is arranged to minimize the attitude errors during periods of reaction wheel speed reversals. Wheel speed is sensed by a suitable device such as a tachometer or Hall elements. Spacecraft three axis attitude is sensed by suitable sensors such as sun sensors, star sensors, gyroscopes or earth horizon sensors. A control network is provided to generate the wheel torque commands necessary to maintain proper three axis attitude. During periods of wheel speed reversal, the control network includes appropriate compensation terms and corrections to the wheel torque command.