Showing papers on "PID controller published in 1982"

Robust multivariable PI-controller for infinite dimensional systems

Abstract: A robust multivariable controller is introduced for a class of distributed parameter systems. The system to be controlled is given as \dot{x} = Ax + Bu, y = Cx in a Banach space. The purpose of the control, which is based on the measurement y , is to stabilize and regulate the system so that y(t) \rightarrow y_{r}, as t \rightarrow \infty , where y r is a constant reference vector. Under the assumptions that operator A generates a holomorphic stable semigroup, B is linear and bounded, C is linear and A -bounded, and the input and output spaces are of the same dimension; a necessary and sufficient condition is found for the existence of a robust multivariable controller. This controller appears to be a multivariable PI-controller. Also, a simple necessary criterion for the existence of a decentralized controller is derived. The tuning of the controller is discussed and it is shown that the I-part of the controller can be tuned on the basis of step responses, without exact knowledge of the system's parameters. The presented theory is then used as an example to control the temperature profile of a bar, with the Dirichlet boundary conditions.

Improved proportional integral-derivative control apparatus

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.

Exact model-matching control of three-dimensional systems using state and output feedback

Abstract: For a general state space model of three-dimensional (3-D) systems, the exact model-matching control problem via state and output feedback ia considered. A frequency domain approach is employed in which the 3-D prototype system (model) is given in transfer function matrix of the form G m(p, w, z). The approach is based on equating the closed-loop transfer matrix function G c(p, w, z) to G m(p, w, z) and solving for the required feedback matrix gains through an application of Kronecker matrix product concept. We start with the static feedback case, and then treat the dynamic feedback problem for the important case of proportional plus integral plus derivative (PID) control. The approach leads to a set of linear algebraic equations, which involve the necessary and sufficient conditions for the exact model matching problem to have a solution. Two simple, but non-trivial examples, are computed.

Sampled value pid controller

Abstract: PURPOSE:To save both labor and time, by identifying the process characteristics under the closed loop control by a sample value PID controller and controlling automatically a sample value PID control system which excels in the suppressing power to a disturbance as well as in the quick responsiveness to the target value. CONSTITUTION:A controlled system is equal to a process 1 which controls the temperature, pressure and flow rate of a plant, where u(t) and y(t) show the process input and output respectively. The process output y(t) is sampled with a prescribed sampling cycle tau to produce a process output y*(N). While a target signal value gamma*(N) obtained by sampling the target value r(t) with the same sampling cycle tau is supplied to a target value filter to produce an output r0* (N). Then a deviation operating part 3 calculates a control deviation e*(N) from the output r0*(N) and the output y*(N). Thus a sample value PID control operating part 5 controls the process 1 based on the deviation e*(N).

Controller of digital control system and method for controlling the same

Abstract: A plurality of proportional plus integral plus derivative ("PID") parameters are prestored in a memory device and at the leading points of respective time segments of a program pattern, PID parameters adequate for the time segment are read out and PID control actions are made by utilizing read out parameters for effecting a process control.

Feedback characteristic polynomial controller design of 3-D systems in state-space

Abstract: For a general state-space model of three-dimensional (3-D) systems the characteristic polynomial (eigenvalue) control problem via state and output feedback is considered. A frequency domain approach is employed which in the scalar input case leads to a set of necessary and sufficient conditions. The multi-input problem is treated by assuming that the state or output feedback gain matrix is expressed as the dyadic product ⊙F = ⊙ ⊙f T of a column vector ⊙β and a row vector ⊙f T . This assumption leads to an equivalent scalar input problem β which is directly solved by using the scalar input results. Concerning the dynamic feedback compensator design problem, the important particular case of proportional plus integral plus derivative (PID) control is considered and treated by essentially the same algorithm, which leads to a linear algebraic system in the unknown parameters, along with some constraint equations upon the closed-loop characteristic polynomial sought.

Proportional, integral and differentiating control device of sample value

Abstract: PURPOSE:To execute an optimum control of a process, by applying a synchronizing signal into a control system, controlling a process by a closed loop. CONSTITUTION:A control deviation e(t) of a target value r(t) and a process signal y(t) is inputted to a sample value control operation part 5. An output signal of the sample value control operation part 5 is added to a synchronizing signal generated by a synchronizing signal generation part 7, and is made a signal for a process control in the sample holding part. On the other hand, a sample value PID control constant, a time constant, etc. are derived by a sample process signal which is obtained through a sampler 8 from an output signal of an addition part 6 and a process signal. The synchronizing signal is a signal containing a multifrequency component of an M sequence, etc., and a pulse transfer function synchronizing part 9 synchronizes a pulse transfer function showing dynamic characteristics of a process 1, by the time series processing.

Optimal tuning of a practical digital pid controller

Abstract: Optimal Tuning of a practical digital PID controller is studied by using the performance indices such as ITAE. IAE. ITSE, and ISE. A simplex searching method that uses the flexible polyhedron is used to find the optimal parameters in the controller. Tuning relations for each of the controller parameters are correlated into the forms that have been used by C.L. Smith and his co-workers. That is: P = A(θ/γ)B or P = A(θ/γ) + B. It is noted that the present tuning relations are more practical in determinations of PID parameters when digital computers or micro-processors are used to implement the practical PID control. For control practice, the use of the existing tuning relations without precautions may result in poor performance in some cases.

Control system of fuel cell power generating plant

Abstract: PURPOSE:To improve dynamic characteristics and decrease by-pass energy loss to increase heat efficiency by controlling an air supply apparatus which supplies air to a fuel cell by installing a heat balance controller. CONSTITUTION:A heat balance controller 8 is installed, and a detected pressure P and a setting pressure Po of discharge air are inputted to a signal converter 9. Its output and the output obtained by giving an added value of a detected value F and a reference value Fo of by-pass flow rate to a PI controller 11 are added and inputted to signal converters 13 and 14, and flow rate of auxiliary burner is controlled with output of the converter 13. Output of the converter 14 is inputted to a signal converter 16 with hydrogen gas temperature T and setting value T1. Fuel flow rate correction signal of a reformer is outputted through an adder 17 and an adder 19 which adds output LD3 of a PI controller 18 and a load follow- up controller. Dynamic characteristics of an air supply apparatus is improved and power generating efficiency is increased.

Self-adjusting simulation and control system

Abstract: The self-adjusting simulation and control system (AMCS) represents a complete operating system for simulation, determination and self-adjusting control, which can be constructed as a closed control system. The self-adjusting simulation system (AMS) is the core of the system in this arrangement. This system consists of a simulation determination algorithm (MIA) and a disturbance variable determination algorithm (DIA). The AMCS operates in an outer and an inner loop. The outer loop tunes the PID controller in a feedback loop, the inner loop determines and compensates for model errors or external load disturbance variables.

Control arrangement for furnace systems in steam or heating boilers

Abstract: Control arrangement for furnace systems in steam or heating boilers, particularly in boilers of the packaged-boiler type, with speed-controlled combustion air blowers, in which, depending on a load signal as first controlled variable, the fuel and the combustion air feed are at the same time adjusted at a particular ratio with respect to one another by a combined actuator, a controlling element controlling the speed of the blower drive motor being provided and a gas density measuring element, particularly an O2 gas density measuring element, supplies a second controlled variable for finely adjusting the speed of the blower drive motor by controlling the said controlling element. The novel feature is that a steady load-dependent speed curve is stored as reference value in a function generator (204) which forwards a first output speed signal (X1), corresponding to the respective load state, as first input variable to a control element (205), that the control element (205) is supplied with the output signal (DV) of a comparator (203), particularly after signal processing via a PID element (202), as second input variable (X2), the comparator (203) being supplied with, on the one hand, the measurement value (PV) of the gas density measuring element (19) and, on the other hand, the output variable (SV) of another function generator (201) in which the gas density is stored as a load-dependent setpoint curve; and that after processing of the first and second input variable, the resultant output variable (X3) is supplied to the controlling element by the control element (205).

Temperature control for condenser

Abstract: PURPOSE:To increase controllability and efficiency of control to the condensate temperature at the condenser of indirect air-cooled type, by using two temperature controllers respectively, of which proportional, integral and differential values predetermined are different from each other, at the time when one unit of variable pitched fan is operated and when a fixed pitched fan is operated in parallel together with the variable pitched fan CONSTITUTION:When a variable pitched fan 11 only is operated, signal X1 from temperature detector is put into a temperature controller 8, and the operating rate Y1 is determined by the proportional value P, the integrated value I, and the differentiated value D of the temperature controller 8 When two units of variable pitched fan 11 and fixed pitched fan 12 are operated at the same time, the detected temperature X2 is put into a temperature controller 8' through AND gate, and the rate of operation Y2 is decided by the other set values of PID Thus, the temperature controllability and efficiency of the condenser of indirect air-cooled type can be increased, by automatically switching over the temperature controller mode in accordance with one-fan operatin and two-fan operation, respectively

Sampled value process controller

Abstract: PURPOSE:To ensure the optimum control state even under the working of a process, by using the sample value control constant which is obtained by switching the sample value PID system to the sample value on/off system when the process dynamic properties are identified under the control CONSTITUTION:In the normal mode, the output signal of a sample value PID control arithmetic part 5 passes through a switch part 7 and is fed to a sample holding part 2 Thus the operation signal is obtained to give the control to a process 1 While in the identification mode, the part 7 is switched to the side of a sample value on/off control arithmetic part 6 Then the operation signal of the process 1 is obtained by supplying the output signal to the part 2 Thus the sample on/off control is carried out in the identification mode, and the sample value PID constant Kc, Ti and Td are calculated from the output of the part 6 or 7 and the process signal y(t) via a sampler 8 This operation is performed at a pulse transmission function identifying part 9, a transmission function arithmetic part 10 and a sample value control constant arithmetic part 11

Auto-tuning system for parameter of pid adjustor

Abstract: PURPOSE:To obtain an auto-tuning system for a parameter of an economical PID adjustor by approximating a controlled system to (temporary delay element + idle time element) and finding out P, I and D parameters from the step response. CONSTITUTION:A step signal is applied from a signal generating circuit 13 through a switch S1 by a tuning start command from a command circuit 12. Supposing that the controlled system is (temporary delay element + idle time element), the gain, idle time and time constant of the controlled system are calculated by a gain calculating circuit 20, a multiplying circuit, an integration circuit, the 1st and the 2nd function generating circuits, an idle time/time constant calculating circuit 21 from the step response. A PID patameter calculating circuit 22 calculates the P, I and D parameters and a PID operating circuit 11 executes PID operation and applies the operated result to the controlled system controlled as a manipulated variable MV to control a process variable.

Automatic regulator and controller for parameter

Abstract: PURPOSE:To find an accurate proportional integral and differential (PID) parameter without exerting an influence upon processes, by generating repetitive pulses as an operation output used when PID parameters of respective operations are found. CONSTITUTION:For example, when a changing-over switch 3 is placed at the side of an automatic parameter regulator and controller A, an operation output X from a repetitive pulse generator 2 is supplied to a process 1 and a process model computer 4. The process 1 outputs an answer output Y, which corresponds to the operation output X, to the computer 4. The computer 4 samples and measures the outputs X and Y in each period to calculate a gain, waste time, and temporary delay constant, and the best PID parameter of the process 1 is calculated and supplied to a PID controller 6. Consequently, since the integral value of the operation output becomes zero, an influence upon a process to be measured is less to attain stableness, and the answer output is a repetitive output, so that the accurate PID parameter which is never influenced by disturbance is calculated.

Temperature controlling method for electric furnace

Abstract: PURPOSE:To assure the application with broad temperature range and to avoid electric shock at switchig, by correcting the deviation between a temperature and an electric power can be zero at the switchig of electric power control and temperature control. CONSTITUTION:The temperature range at temperature increase/decrease is split into temperature control and electric power control, and th deviation between temperatures or powers is detected at switching and corrected so that it is zero. For example, at a low temperature range, a thyristor 8 is controled with a PID controller 3 to supply power to an electric furnace 13, and the temperature of the furnace reaches a given value, which is detected by a temperature sensor 14 and an electric power-temperature switch 16 is operated. In this case, a switching signal operates a signal storage device 6 to store the output signal of the PID controller 3 and a program setter 1 changes over the system from electric power to temperature control. The deviation at this time is detected at deviation detectors 4, 5 and a fast feed signal circuit can be switched so that the set index of a controller coincides with a moving pointer.

Acceleration controller for air fuel ratio feedback control of internal combustion engine

Abstract: PURPOSE:To abate exhaust of noxious gases at the moment of zero starting, by shifting a pulse motor for driving an air fuel ratio control valve to a given position which is from hence to be the starting point of feedback control. CONSTITUTION:A feedback controller of air fuel ratio which drives an air fuel ratio control valve of a pulse motor 13 in accordance with an O2 sensor is equipped with an air fuel ratio discriminator 204, PI control circuit 203 and pulse motor driving units 209, 211 in an EPU20. An engine revolution discriminator 205a also set to the controller for processing output of engine revolution sensors 28, 29 provides an FF205c with an output from its terminal (b), as it monitors the state of acceleration at the moment of zero starting. An output (Q) from the FF205c actuates the PI controller 203 to interrupt feedback control and put out a pulse through a comparator 210 for shifting an air fuel ratio control valve to a given position.

Process control system

Abstract: PURPOSE:To previously prevent the occurrence of an accident at a plant, by switching the automatic operation mode to the manual operation mode for a subject of control in case when some fault is detected from the detection variation factor obtained by a monitor means CONSTITUTION:This control system comprises a detecting part 31 that detects the process quantity from a subject of control, a controller 32 and an operation terminal 40 that converts the output given from the controller 32 into the operation quantity and influences the subject of control An input arithmetic part 33 is provided to the controller 32, and the arithmetic output is applied to a control part 35 to perform a PID operation The result of this operation is applied to the terminal 40 via an automatic-manual changeover part 36 In addition, an arithmetic part 38 a PV variation factor is provided to the controller 32 to calculate the variation factor of the PV value A monitor switch 39 functions when the output of the part 38 exceeds a prescribed level and drives the part 36 to change the automatic operation mode to the manual operation mode

Control parameter tuning device of digital controller

Abstract: PURPOSE:To efficiently change a control parameter, by providing a higher rank processor for operating a control parameter in accordance with a data from a digital controller which is equipped with a disturbance generating means, and an output measuring means of a process to be controlled. CONSTITUTION:A digital controller 211 outputs a mainpulated variable UK by executing a PID operation to a deviation eK, and it is equipped with an M sequence tuning signal generation part 32, is superposed on the manipulated variable at a suitable time, and it is outputted. The extent of measurement YK in that case, the deviation eK, the manipulated variable UK, etc. are stored in a data file 33, and are sent to a higher rank processor 23 through a transmission line 22. The higher rank processor 23 executes a tuning operation of a process, derives an optimum control parameter, and sends it to the digital controller 211.

The Delay Controller: An Improvement Over PID Regulator

Abstract: If the derivative term in a proportional-integral-derivative (PID) controller is replaced by a suitable time delay, the noise contamination in the output is smoothed out while the other good effects of PID action are preserved. Sufficient conditions for the choice of time delay are established. Optimization of such a system with a prescribed degree of stability is worked out and compared with the response of a system with PID controller. The output is substantially noise free.

Controller of sample value pid

Abstract: PURPOSE:To eliminate the real control period of a controller and to realize a high working efficiency of a plant, by identifying the process with a specific identification signal during the control of a closed loop and calculating the sample value control constant from the result of the identification. CONSTITUTION:An identification signal produced from a persistently exciting signal produced at an identification signal generating part is added 6 to the output signal of an arithmetic part 5 for sample value PID control to obtain a control signal. Then the process parameter is identified at a pulse transmission function identifying part 9 by the said control signal and a process signal obtained by sampling the degree of control of a process 1. Furthermore the transmission function of a region S is calculated through a transmission function arithmetic part 10 and by the pulse transmission function of the process which is obtained at the part 9. Based on the result of operation, the control constant of the part 5 is calculated at an arithmetic part 11 for sample value control constant.

Process controlling device

Abstract: PURPOSE:To control a process, by converting the process variable signal to a digital quantity by sampling and subjecting this digital signal to the operation processing and giving the operation result to an operation device. CONSTITUTION:In a position controller, when its own output of PID operation is connected to an input terminal P1, a preceding output value out of operation is taken in, and thus, this connection is equivalent to an internal connection, and a speed operation output DELTACN is integrated practically in the operation output obtained in an output terminal OUT, thus obtaining a position output. In a speed controller, when terminals are so connected that 0% fixed value data FIX is given to the input terminal P1 and a turn-on enable signal INL is given to an input terminal P2, the speed operation output DELTACN is outputted as it is as the operation output obtained in the output terminal OUT, thus constituting a speed output PID controller.

Application of Incremental Control to HVAC Processes

Abstract: This paper describes the application of digital PI and PID control algorithms with incremental outputs to HVAC processes using conventional pneumatic actuators. Particular attention is paid to the proper selection of the components for the digital/pneumatic interface. A discussion of hysteresis correction, error deadhand, sampling rates and tuning techniques is included.

Direct digital control of superconducting magnet

Abstract: The SM (superconducting magnet) current feedback control of I-C unit (inductor-converter unit) has to be designed to maintain stability, considering that the time constant of transfer function from SM current to SM terminal voltage is very large. For accurate control, it is also very important to take into account the current and magnetic field distributions inside the SM, ac loss and stray capacitances between coils. In this paper, direct digital control systems such as PID system, first-order time lag system with dead time element, finite time setting control system (FTSC) and model reference adaptive control system (MRAS) are proposed. Control characteristics of these control systems are analyzed by experiment and simulation.