Showing papers on "Proportional control published in 1984"

A variable structure approach to robust control of VTOL aircraft

Abstract: This paper examines the application of variable structure control theory to the design of a flight control system for the AV-8A Harrier in a hover mode. The objective in variable structure design is to confine the state trajectories to a subspace of the total state space. The motion in this subspace is insensitive to system parameter variations and external disturbances that lie in the range space of the control. A switching type of control law results from the design procedure. The control system was designed to track a vector-valued velocity command. For comparison, a proportional controller was designed using optimal linear regulator theory. Both controllers were evaluated for their transient response performance using a linear model; then a nonlinear simulation study of a hovering approach to landing was conducted. The variable structure controller outperformed its linear counterpart in the presence of wind disturbances and plant parameter uncertainties afforded by the simulation.

Signal Processing for Proportional Myoelectric Control

Abstract: Proportional myoelectric control of powered prostheses requires the estimation of a time-varying control signal from the patient's myoelectric signal. Since the myoelectric signal is a zero-mean stochastic process, a nonlinearity is a necessary element of the estimator. Typically, a full-wave rectifier is used for this nonlinearity, followed by a low-pass filter to complete the estimation of the control signal. In this work, it is proposed to use a logarithmic nonlinearity, followed by a linear minimum mean-square error estimator. The logarithmic nonlinearity maps the myoelectric signal into an additive control signal-plus-noise domain in which the Kalman filter is employed to estimate the control signal. The theoretical performance of this estimator is obtained and verified by experiments.

Quaternion feedback for spacecraft large angle maneuvers

Abstract: This paper presents the stability and control analysis for large angle feedback reorientation maneuvers using reaction jets. The strapdown inertial reference system provides spacecraft attitude changes in terms of quaternions. Reaction jets with pulse-width pulse-frequency modulation provide nearly proportional control torques. The use of quaternions as attitude errors for large angle feedback control is investigated. Closed-loop stability analysis for the three-axis maneuvers is performed using the Liapunov stability theorem. Unique characteristics of the quaternion feedback are discussed for single-axis motion using a phase-plane plot. The practical feasibility of a three-axis large angle feedback maneuver is demonstrated by digital simulations.

Control device for continuously variable transmission

Abstract: A control device for a continuously variable transmission performs a feedback control wherein an integral control gain and a proportional control gain of the feedback control are varied depending upon an operating position assumed by a shift actuator.

Hydraulic system with proportional control

Abstract: An hydraulic control system is disclosed for energizing a load, such as the lift cylinder of an electric lift truck, with a minimum of power loss during the transition from zero to full energization, i.e. during the feathering range. An electric motor drives a positive displacement pump which supplies the flow requirements of different load circuits, one having a greater flow requirement than the other and requiring higher pump speed. A proportioning valve of the open center type provides full flow to the tank when the valve is closed and full flow to the load circuit having the greater flow requirement when the valve is open. A manually actuable lever actuates the valve through the feathering range with the pump motor in a low speed range and actuates a speed control switch to operate the motor in the high speed range when the valve is fully open.

Gas control device

Abstract: PURPOSE:To eliminate the necessity due to negative pressure for increasing force opening both a solenoid valve and a proportional control valve, by providing a check valve so as to prevent the negative pressure from being generated in an enclosed passage formed by an outlet side of the solenoid valve and an inlet side of the proportional control valve CONSTITUTION:A solenoid valve 1 and a proportional control valve 9 are connected in series A control device, when its operation is stopped, forms an enclosed passage 21 by an outlet side 3 of this solenoid valve 1 and an inlet side 19 of this proportional control valve 9 The device provides a check valve 27 between this enclosed passage 21 and an outlet side of the proportional control valve 9 And fuel gas infiltrates into the rubber material of a diaphragm 10 when the operation is stopped for a long time As a result, negative pressure is generated in the enclosed passage 21, and the control device is constituted such that the check valve 27 opens eliminating the negative pressure

Robust Design of a Digital PID Predictor Controller

Abstract: A digital proportional integral-derivative (PID) predictor controller is analyzed, and its advantages relative to the normal PID controller are derived. A design procedure which results in a robust control system is developed. This procedure applies to both the PID predictor and the normal PID controllers. A regulator carbon dioxide control system which requires disturbance rejection is designed as an example.

Steam Temperature Prediction Control for Thermal Power Plant

Abstract: An advanced control method using a microprocessor is developed for boiler steam temperature control of thermal power plants. A process dynamics model with the Kalman filter in the controller is presented which describes the dynamic plant behavior. Using the model, future changes in steam temperature are predicted and the fuel flow rate compensated accordingly. The model is also used to adjust the control parameters, i.e. proportional and integral gains, to provide values which ensure stable system control.

Design of a control system for maintaining a normal arterialpCO2 by artificial respiration

Abstract: The paper describes the design of a feedback control system which maintains the arterial pCO2 near the normal level during artificial respiration in spite of disturbances in variables such as the CO2 production rate, the dead space and blood flow. Five models were used to analyse the control system. Using the linear model, a proportional controller with a lag/lead compensator was designed to satisfy the requirements derived from the performance of the biological respiratory system. Digital simulation confirmed that the control system responds well to the above mentioned disturbances and that it is little affected by parameter variations in the control system.

Improved control system for a power delivery system having a continuously variable ratio transmission

Abstract: A control system and method for a power delivery system, such as in an automotive vehicle, having an engine (10) coupled to a continuously variable ratio transmission (CVT) (14). Totally independent control of engine and transmission enable the engine to precisely follow a desired operating characteristic, such as the ideal operating line for low fuel consumption. CVT ratio is controlled as a function of commanded desired system performance (e.g., power or torque) and measured actual system performance, such as CVT torque output, while engine fuel requirements (e.g., throttle position) are strictly a function of measured engine speed. Fuel requirements are therefor precisely adjusted in accordance with the ideal characteristics for any load placed on the engine. Appropriate controls prevent anomalous engine and vehicle behavior, and allow for transient start-up from rest. In a preferred embodiment a proportional controller is used to set the driving diamter of the driver shave of a V-belt traction drive CVT, while the drive diamter of the driven sheave is controlled by a torque ramp.

Hydraulic clutch connection controller for power shift type transmission

Abstract: PURPOSE:To miniaturize a device as well as to make the control of a hydraulic clutch smoothly performable in a short span of time according to car load, by installing a selector valve in a duct line between hydraulic pumps along with a solenoid proportional control valve, in case of the above-captioned device for vehicles available in civil engineering and building equipment. CONSTITUTION:With a hydraulic clutch operated for connection, when a selector valve 24 is changed over to a position N from M, accelerating from low to high in a forward speed, this position signal is inputted into a controller 28 which, in consideration of car load such as an engine speed or the like in time of the forward low speed, outputs an opening command to a solenoid proportional pressure control valve 27 in accordance with the short charging time corresponding to a hydraulic clutch 23b for the high speed stored in memory and high charging pressure. A control valve 27 opens and secures the initial pressure so as to become the specified pressure during the charging time inputted. Next, opening adjustment takes place and it is kept as the connection starting pressure. Other selecting operation takes place in the same manner. With this, the controller can be smoothly operated according to the car load.

Hydraulically driving device with warming-up function

Abstract: PURPOSE:To automate the warming-up control by providing a warming-up means which keeps a center-bypass type direction change-over valve in the specified opening position in response to a warming-up instruction. CONSTITUTION:A proportional control solenoid valve 18 is connected via a shuttle valve 19 to the pilot pipe passage of a center-bypass type direction change- over valve 2 and a warming-up control circuit 16 and a temperature detector 15 are connected to the controlling part of the proportional control solenoid valve 18. When the temperature of working oil is reduced below the specified temperature at which warming-up may be needed, the signal from the temperature detector 15 actuates a warming-up control circuit 16 so that the pilot pressure signal of a specified level from the proportional control solenoid valve 18 is sent to the center-bypass type directional change-over valve 2 to keep it in the specified opening position. Accordingly, the warming-up may be controlled not manually but automatically.

Electro-hydraulic control arrangement

Abstract: An electro-hydraulic control arrangement (10) is proposed in which a 3-way control function is realised for proportional control by means of two two-way built-in valves. The inflow line (13) to a hydraulic motor (11) is influenced by a first built-in valve (17), the control piston (19) of which, lying in a position control circuit (39), is pilot-controlled by an electro-hydraulic servo valve (28). The control connection (25') of a second built-in valve (41), which controls the outflow line (15) from the hydraulic motor (11), is connected via a pressure-divider circuit (44, 43) to a second working connection (32) of the servo valve (28). The servo valve (28) controls both built-in valves (17, 41) in opposite directions so that rapid relief can be controlled as a function of an electric desired-value signal even at a large compression volume in the hydraulic motor (11).

Feedback control method for number of idle revolutions of internal-combustion engine

Abstract: PURPOSE: To stabilize control of the number of revolutions during idle running and to prevent the occurrence of control lag of the number of revolutions, by a method wherein, based on a correction value decided responding to the generating condition signal value of a generator, an operation amount of a control valve, regulating an intake air amount, is corrected. CONSTITUTION: In a step 71, when feedback control of the number of idle revolutions is rendered ineffective during preceding TDC, an initial value DAI n-1 during the starting of control is set to an opening valve duty ratio (DXREF+ DE.XAIC), wherein DXREF is a reference value, DE is an electric load correction value, and XAIC is the coefficient of increase amount correction. In a step 74, an integral control correction value ΔDI and a proportional control item value Dp are determined. In a step 75, an electric load correction value ΔDE is decided. This enables stable control of the number of revolutions during idle running, and prevents the occurrence of control lag of the number of revolutions. COPYRIGHT: (C)1986,JPO&Japio

Gas flow-rate controller

Abstract: PURPOSE:To improve the precision in flow-rate control by forming the magnetic saturation parts onto the material constituting an electromagnetic driving part in the proportional control range for a proportional control valve, thus reducing the gain of the flow-rate control characteristic. CONSTITUTION:In the electric conduction state, a set signal SS and a combustion-load signal are compared with each other in a comparator 19, and the deviation signal therefrom transforms into a d.c. current having dither signals superposed in a control circuit 18, and is supplied into a coil 33. A plunger 37 has a notched part 38 for reducing the sectional area for magnetic saturation. Though magnetic saturation is generated when the electric current increases over a certain value, the increased hysteresis due to magnetic saturation can be reduced by the dither signals.

Experimental Investigation of Adaptive Control of a Distillation Column

Abstract: A unified approach to discrete-time explicit model reference adaptive control schemes has been applied to the multivariable control of a pilot scale packed distillation column separating a mixture of methanol and water. The control scheme is based on Landau-Lozano's approach (1981), and a method of control costing of Clarke and Grawthrop (1975) and an estimation method of nonzero d.c. value are also incorporated. The effects of the model order and time delays are illustrated. The resulting control performance is compared with that achieved with conventional proportional plus integral action.

Electro-hydraulic proportional control valve

Abstract: An electro-hydraulic proportional control valve includes an electro-hydraulic pilot valve, an inlet pressure reducing valve, and a directional control valve The electro-hydraulic pilot valve receives an electrical input signal and provides a hydraulic signal to the directional control valve in response to the electrical signal The inlet pressure reducing valve modulates fluid flow from a pump to the directional control valve to maintain a constant pressure drop across the directional control valve under all conditions The directional control valve includes a directional control valve spool which shifts between a neutral position, a leftward displaced position, and a rightward displaced position in response to the hydraulic signal from the electro-hydraulic pilot valve The directional control valve spool includes a range adjustment device for adjusting and setting the flow rate through the directional control valve

Binary and proportional control for a feedback carburetor

Abstract: A control system for a feedback carburetor in which a controlled vacuum is applied to the carburetor fuel bowl to reduce the fuel flow rate and provide maximum fuel economy. Engine speed is monitored and reduced a predetermined amount during steady state cruising through use of an air control solenoid to apply the controlled vacuum. The controlled vacuum is removed during acceleration or when engine speed is outside the range of steady state cruise speed.

Space Shuttle separate-surface control-system study

Abstract: A control system concept is presented that produces proportional control of yaw moment for the space shuttle from early entry to Mach 2 with only software modifications of the vehicle. It uses separate deflections of the inboard and outboard elevon surfaces and is evaluated, by determining the maximum static yawing moment available by considering the deflection limits of the elevon surfaces. A proportional moment slightly in excess of that produced by the most effective reaction control system (RCS) jet for yaw control can be obtained. In addition to the static moment study, a control law is designed which is intended to produce desired flying qualities.

Buffer for hydraulic cylinder

Abstract: PURPOSE:To secure the superior buffer performance at any operation speed of a hydraulic cylinder by supplying a pressure for turning-back a spool in the neutral drection in relation to the operation speed of the hydraulic cylinder a gainst a pilot pressure supplied to the spool of a hydraulic control valve through a manual reducing valve. CONSTITUTION:A pressure supply means, e.g., an electromagnetic proportional control valve 27 receives an electric signal from a calculator 28 and makes contact with a pilot pump 22. A position detector 29 detects the position of the piston of a hydraulic cylinder 10 at each unit time and outputs the position signal into the calculator 28. Shuttle valves 30 and 31 select the higher pressure out of a pilot pressure supplied through manual reducing valves 25 and 26 and a pressure supplied through an electromgnetic proportional control valve 27, and supplies said pressure into the spool of a hydraulic control valve 21. The calculator 28 outputs the instruction signal for increasing the pressure supplied, into the electromagnetic proportional control valve 27, when the operation speed is high when a buffer starts operation.

Development of an electro-hydraulic floating double-disc valve

Abstract: There is a need for low-cost switching and proportional electro-hydraulic valves with low contamination sensitivity and good reliability. In an attempt to meet this need, a novel electro-hydraulic floating double-disc valve has been developed to the stage where it can be used to control hydraulic cylinders or motors directly. As the valve is significantly underlapped, problems still remain in achieving adequate hydraulic stiffness in the proportional mode of operation. The valve operation, which relies on the complex interaction between fluid and electro-magnetic forces acting on the valve discs, is described and a theoretical model of the fluid and electro-magnetic characteristics of the valve is presented. The theory shows satisfactory agreement with experimental data. A pre-production version of the double-disc valve has been designed and manufactured and it incorporates ideas for manufacturing cost reduction while at the same time conforming to CETOP 3 international valve port standards. This valve has been successfully tested as a switching or proportional device when controlling two different cylinders. Proportional control of the valve is achieved using Pulse-Width-Modulation technique. British Technology Group and University of Surrey have applied for a patent on the valve. The patented floating-disc valve has the following features: (a) 3 way or 4 way 2-position or proportional action with minor changes to produce the two types of action, (b) cartridge construction with interchangeable components, (c) low contamination sensitivity, (d) few critical dimensions, (e) no sliding surfaces, (f) CETOP valve port configuration and (g) potentially capable of operating with corrosive or non-lubricating fluids.

Control unit of hydraulic cylinder

Abstract: PURPOSE:To simplify the constitution and reduce the cost of a control unit including a proportional reducing valve by controlling one direction changing valve with only one proportional control valve. CONSTITUTION:An apparatus for controlling a cylinder 10 by a direction changing valve 11 includes a two-position solenoid valve 14 for selecting pilot paths 12, 13 to the direction changing valve 11 and a proportional reducing valve 15 disposed upstream from the valve 14. The proportional reducing valve 15 is operated in proportional to an input signal, so that in the illustrated condition, a connecting path 19 is connected to a tank 21, and at the time of switching opeation, an auxiliary pump 22 and a connecting path 19 are connected with each other. The solenoid valve 14 and the proportional reducing valve 15 are respectively connected to a direction discrimination circuit 23 and a proportional control circuit 24 and the respective circuits 23, 24 are controlled to operate according to an input signal of an input portion 25.

Proportional versus on/off control: a detailed comparison

Abstract: Through a series of single-day experiments, the authors compared in detail the performance of on/off and proportional control strategies for solar hot water systems. The experiments encompass a variety of meteorological conditions, and include start-up with both warm and cool storage tanks. Insolation, tank temperatures, and pump energy use are monitored nearly continuosly throughout the day. Results show a consistent advantage in thermal energy gain for proportional control, especially under conditions of low or variable insolation, although proportional control requires considerably more parasitic pumping energy under these conditions.

Digital speed control system with integral-proportional control

Abstract: A microprocessor based speed control system for a dc motor drive is described. The motor is fed by a three phase fully controlled bridge the delay angle of which is set directly by the microprocessor. To control the speed of the drive a PI control algorithm is implemented first and the experimental results are obtained for changes in the load torque and the reference speed. The proportional term of tae PI controller is then moved from the forward loop to the feedback loop, resulting in an I-P control algorithm. Experimental results are obtained and compared with the previous ones. It is seen that the I-P controller results in a better dynamic performance.

Proportional controller for brake

Abstract: PURPOSE:To have optimum proportion of distributed braking force in accordance with the load applied to a car, by furnishing a solenoid-operated valve between the inlet to a proportioning valve and the control chamber, and by controlling this opening/closing valve so as to present a performance with a transition of curvature as in correspondence to the load applied to the car. CONSTITUTION:A solenoid valve 29 is interposed in a communication line to connect a control chamber 282 and a plunger chamber 281 leading to the inlet port of a proportioning valve 28. The transition point of curvatures of the front wheel braking pressure and rear wheel braking pressure is changed by a push force, at which a spring pressure adjusting plunger 284 pushes a coil spring 285 operated by a pressure from the above-mentioned control chamber 282. The pressure in the control chamber 282 is controlled by the above-mentioned solenoid valve 29, which is in turn controlled by CPU. That is, the CPU senses the load applied to the car as well as the brake operating speed and the deceleration, the latter two being made during brake application, and these three values shall serve setting of the transition point, and when the input port pressure has attained this transition point, current is supplied to the solenoid valve 29.

Controller for gas combustion

Abstract: PURPOSE:To contrive cost lowering and compactness of a controller of gas combustion, by a method wherein both of control performance and a closing function of a proportional control valve are satisfied, through which a closed nozzle is made unnecessary. CONSTITUTION:The titled device is so constituted that both a closing function and favorable control performance of the proportional control valve 6a are satisfied by making a valve seat 7 and a valve body 8 of a proportional control valve 6a closable by an elastic body 10a for closure through an elastic component 8a and providing a lock releasing circuit 21 aleinating instantaneously only at the time of ignition to a gas burner 15a lock between the valve seat 7 and the valve body 8 due to the effect of the elastic component 8a that has been provided. With this construction a closing solenoid valve becomes unnecessary, the titled device can be made inexpensive, compact and moreover control function can be made favorable.

Process controller of high response speed

Abstract: PURPOSE:To prescribe clearly a reset time and a rate time which give a high response speed, by setting an apparent rate time of a proportional integral element to a value which is practically equal to the time constant and is two or more times as long as an apparent reset time of this element CONSTITUTION:A process 3 consists of a proportional control solenoid valve 3A and a flow rate sensor 3B, and the degree of opening of the solenoid valve 3A is varied by the output current of a proportional integral element 1 to regulate the flow rate of gas from a gas supply source 4 Then, the element gives an operation signal to the process 3 The solenoid valve 3A has a conversion constant Ka The flow rate sensor 3B has a time constant TP and a proportional gain M, and the flow rate detected by this sensor 3B is applied to a proportional integral element 2 This element 2 converts the output of the sensor 3B to an output voltage y(t) which is a function of a time (t) This voltage y(t) is applied to a point 6, where the input side of the element 1 and a setting part 5 are connected, through a negative feedback path 7