Showing papers on "Proportional control published in 1973"

Automatic Generation Control Part II-Digital Control Techniques

Abstract: Techniques are described for the application of automatic digital generation control and for the evaluation of performance from indices which measure the effectiveness of control relative to the control effort. The basic objectives of generation control are reviewed and non-conventional control logic is described with non-linear filtering features designed to be effective in following basic load trends and large deviations while reducing control action in response to the higher frequency random components. Examples of simulations are included.

System and method for operating a steam turbine with digital computer control having integrator limit

Abstract: In a system and method for automatically starting, synchronizing and operating a steam turbine, proportional plus integral feedbck control utilizing digital computer systems is adapted to correspond to physical valve operation by applying integration limits. Useful for both speed and load control modes of operation, the demand signal is compared with prior values thereof, and the differential is both multiplied by a proportional gain factor, and integrated in the computer utilizing numerical integration techniques. The integrated total is kept within a desired range by applying upper and lower limits, and the limited integral is combined with the proportional factor, further limited, as desired, and appropriately scaled for use as a process variable.

Direct current arc power supply

Abstract: An arc power supply system having a three phase transformer and a full wave rectifier which includes silicon controlled rectifiers. A feedback control system includes first and second cascaded operational amplifiers. The first amplifier sums (1) a reference set point signal, (2) an adjustable voltage feedback signal and (3) an adjustable current feedback signal. The first amplifier provides low pass filtering to smooth the otherwise high ripple content of the two feedback signals. The second amplifier provides both integral and proportional control and drives a firing circuit. By the use of a single slope adjustment control, the current and voltage feedback signals may be adjusted to provide infinite and continuous control of the voltampere characteristic of the power supply between a constant current characteristic and a constant potential characteristic. An adjustable start circuit provides control of the average output voltage, and hence the initial arc energy, at the start of operation to more easily establish the arc.

A model based technique for the design of flight directors

Abstract: A new technique for designing flight directors is discussed. This technique uses the optimal-control pilot/vehicle model to determine the appropriate control strategy. The dynamics of this control strategy are then incorporated into the director control laws, thereby enabling the pilot to operate at a significantly lower workload. A preliminary design of a control director for maintaining a STOL vehicle on the approach path in the presence of random air turbulence is evaluated. By selecting model parameters in terms of allowable path deviations and pilot workload levels, a set of director laws is achieved which allows improved system performance at reduced workload levels. The pilot acts essentially as a proportional controller with regard to the director signals, and control motions are compatible with those appropriate to status-only displays.

Design of High Speed Hydraulic Position Servomechanisms Using Optimization Techniques

Abstract: This paper collates and extends recent research on the design of hydraulic position servomechanisms using optimization techniques in place of conventional linear feedback methods. Different methods of control are proposed on the basis of a formal application of time optimal control theory followed by an analytical study of the time optimal controller. Optimum designs for the proposed controllers are then derived using a digital computer simulation and parameter optimization sub-routines. Finally, the performance of the proposed controllers is compared with the best performance that can be achieved using conventional proportional control.

Floating position proportional control system

Abstract: A floating position proportional control system for positioning a working tool of a road machine comprises a sensor for producing a signal indicative of the deviation of the working tool from a reference, a feedback potentiometer having a floating range, an amplifier for producing a signal representative of the error existing between the sensor signal and the signal from the feedback and an output for positioning the working tool according to said error signal. The feedback potentiometer has mechanical stops at either end and the wiper arm is frictionally driven such that when the wiper arm reaches one of the mechanical stops the drive will slip and the wiper arm will move no further.

Design and Application of a Time-Optimum Controller for a Class of Nonlinear Processes

Abstract: A procedure was developed to extend time-optimum control of linear processes to a class of nonlinear processes consisting of a second-order overdamped linear process followed by a nomemory nonlinearity. Bang-bang control was combined with a proportional-integral-derivation (PID) controller to achieve time-optimum control for set-point changes and good regulator operation for minor disturbances. This dual-mode controller was implemented with a small digital computer. The settling time for step set-point changes with dual-mode control was compared to that with PID control alone. A factor of 2 improvement was achieved through time-optimum control. The dualmode control was successfully applied to an actual nonlinear process.