Showing papers on "Control variable published in 1989"

Real-time computation of feedback controls for constrained optimal control problems. Part 2: A correction method based on multiple shooting

Abstract: On the basis of Part 1 of this paper, a numerical method is developed for the real-time computation of neighbouring optimal feedback controls for constrained optimal control problems. We use the idea of multiple shooting to develop a numerical method which has the following properties: 1. The method is applicable to optimal control problems with constraints (differential equations, boundary conditions, inequality constraints, problems with discontinuities, etc.). 2. The control variables and the switching points are computed for the remaining time interval of the process. 3. All constraints are checked. 4. The method is appropriate for real-time computations on onboard computers of space vehicles. 5. The scheme is robust in that controllable deviations from a precalculated flight path are much larger than deviations typical for perturbations occuring in space vehicles. The re-entry of a space vehicle is investigated as an example. One problem contains a control variable inequality constraint with a large variety of different switching structures, including problems with a corner. A second problem contains a state variable inequality constraint with one or two boundary points or one boundary arc. The different switching structures depend on the tightness of the constraints.

Simple nonsingular control approach to fed-batch fermentation optimization.

Abstract: Determination of the optimal feed rate for fed-batch fermentation is normally a problem in singular control with a state inequality constraint and as such is, in general, difficult to solve, especially for those described by a large number of dynamic mass balance equations. In this article we use a new set of state variables and the culture volume as the control variable. In this way the problem is converted to one of nonsingular control with the magnitude and rate constraints on the manipulated variable and can be numerically solved by a gradient-based technique, thus avoiding the difficulty associated with singular control problems. Examples are given to illustrate the method.

Digitally controlled variable resistor

Abstract: A compact and inexpensive variable resistor circuit has a value of resistance that can be set by a data signal. The variable resistor includes a number of variable individual resistances connected in series, and an electronic switch connected in parallel across each individual resistance. The values of the individual resistances are chosen to include a basic resistance value and a compensating resistance value, which corresponds to the impedance of the associated electronic switch in its closed state. The basic value is chosen from the progression 2 0 , 2 1 , 2 2 , 2 3 , and so on, so that the resistance of the variable resistor corresponds to the binary value of data applied to control the electronic switches. Other aspects of the invention include input and control circuitry which is designed to minimize its size and allow it to be packaged on an integrated circuit.

Apparatus for determining control characteristics for automobiles and system therefor

Abstract: A control device for an automobile capable of changing the relationship between the driver's input and the controlled variable of the automobile by the driver's individual characteristics so as to characterize the automobile.

Optimal Dynamic Control of Resources in a Distributed System

Abstract: The authors quantitatively formulate the problem of controlling resources in a distributed system so as to optimize a reward function and derive optimal control strategies using Markov decision theory. The control variables treated are quite general; they could be control decisions related to system configuration, repair, diagnostics, files, or data. Two algorithms for resource control in distributed systems are derived for time-invariant and periodic environments, respectively. A detailed example to demonstrate the power and usefulness of the approach is provided.

Driving of Non-Linear Time-Dependent Ocean Models by Observation of Transient Tracers—A Problem of Constrained Optimisation

Abstract: The problem of “driving” the phase space trajectory of an ocean model such that it comes “close” to observations distributed in space and time is discussed. The approach taken is one of optimization where a distance function I is minimized while the model equations act as hard (i.e. equality-) constraints. In this case model trajectories are subject only to model physics, initial- and boundary conditions. As a consequence changes in the trajectories can only be achieved via control variables u that describe the conditions mentioned like external forcing driving the circulation or that describe model physics like friction and diffusion parameterization. By changing only control variables and letting the model evolve according to its equations of motion the constrained problem in the space of model and control variables is changed into an unconstrained problem in the space of control variables. The optimization is performed iteratively: first an initial guess of u is taken, then the distance function I is evaluated by integrating the ocean model for a time interval in which tracer (or other) measurements are available. The gradient of I with respect to u is calculated with the aid of the adjoint model which is integrated backwards for the same time interval. Subsequently an unconstrained minimization algorithm is used to perform the optimization in u-space.

Load frequency self-tuning regulator for interconnected power systems with unknown deterministic load disturbances

Abstract: A new method is presented for designing load frequency self-tuning regulators for interconnected power systems having unknown deterministic load disturbances. A discrete-type optimal control law is obtained by defining a cost function with a term for presenting the constraints on the control effort and then by minimizing it with respect to the control variable. An attractive feature of the proposed control scheme is that the effect of the load disturbances is decoupled from the plant output and the large value of control is discouraged indirectly by penalizing the rate of change of control. Another feature is that it considers the time delay due to the identification and control computations and the transmission time of the system data over the telemeter links to the controlling plant. The control effects of the proposed regulator are examined using digital simulations of a two-area power system provided with reheat steam turbines.

Running control device for vehicle

Abstract: PURPOSE: To follow in running most excellently by detecting a relative position with respect to a car running ahead and the steering angle of a driver's car, evaluating a risk while considering whether or not his car is running toward the car running ahead so as to control the running of his car, and thereby evaluating the risk while meeting the actual operation feeling of his own. CONSTITUTION: A risk computing means 26 and a proper distance between cars computing means 28 are provided, the former computes a risk index based on signals from a laser radar device 20, a vehicle speed sensor 22 and a steering angle sensor 24, and the latter computes a proper distance between a car running ahead and a driver's car based on the risk index computed by the risk computing means 26. The acceleration/deceleration controlled variable of his car is computed by a proper vehicle speed actuated variable control means 30 based on the proper distance between cars computed by the aforesaid proper distance between cars computing means 28. This thereby permits a relative position with respect to the car running ahead and steering angle of his car to be detected for evaluating a risk while it is taken into consideration whether or not his car is running toward the car running ahead, thereby making it possible to follow in running most excellently. COPYRIGHT: (C)1991,JPO&Japio

Position control method

Abstract: In a position control system having force as a manipulated variable and position as a controlled variable, negative feedback of position and velocity is performed. Positive feedback of acceleration is performed through a first order lag circuit. Alternatively positive feedback of velocity is performed through a quasidifferential circuit. By the combination of negative and positive feedback, it is possible to stabilize vibration characteristics of the mechanism, which tends to make the control system stable, and to achieve position control with high gain, high response and high accuracy.

An algorithm to solve dynamic models

Abstract: This paper presents an algorithm to solve recursive systems, formulated in discrete or continuous time, which have an endogenous state variable. The basis of the algorithm is a fixed point equation in the function from the state variables to the control variables.

Artificial neural circuit network type fuzzy controller

Abstract: PURPOSE: To efficiently construct a fuzzy control system with high performance and to improve control performance by simultaneously adjusting membership functions used for a condition part and a conclusion part. CONSTITUTION: #1 and #2 state variables are inputted from an input part 1 and a prescribed value from a generation part 2. The arithmetic neurone part 4 of an artificial neural circuit network type fuzzy controller individually multiplies a couple of adjustable synapse loads corresponding to a parameter showing the central values of the membership functions of respective fuzzy control rule condition parts 3, and shapes with respect to inputs, and the part 4 operates assignment degrees for respective membership functions. A neurone part 5 operates adaptation for respective control parts 3 and a neuron part 6 operates the total sum of the areas of fuzzy sets for respective fuzzy variables. A non-fuzzy part 8 obtains control variable values and an error operation part 9 calculates the error of the control variable values and a control variable value being a criterion and obtains a feedback signal. Consequently, an error signal is controlled so that it becomes the smallest. COPYRIGHT: (C)1990,JPO&Japio

Discrete-time optimal control by neural network

Abstract: A neural network determines optimal control inputs for a linear quadratic discrete-time process at M sampling times, the process being characterized by a quadratic cost function, p state variables, and r control variables. The network includes N=(p+r)M neurons, a distinct neuron being assigned to represent the value of each state variable at each sampling time and a distinct neuron being assigned to represent the value of each control variable at each sampling time. An input bias connected to each neuron has a value determined by the quandratic cost function for the variable represented by the neuron. Selected connections are provided between the output of each neuron and the input of selected other neurons in the network, each such connection and the strength of each such connection being determined by the relationship in the cost function between the variable represented by the connected output neuron and the variable represented by the connected input neuron, such that running the neural network for a sufficient time to minimize the cost function will produce optimum values for each control variable at each sampling time.

Sliding Mode Control of Automotive Powertrains with Uncertain Actuator Models

Abstract: An alternative formulation of the sliding mode control method for dealing with the uncertainties in actuator or control dynamics is presented in this paper. The advantages of the formulation are in the reduced computational requirements and simplified procedures for meeting robustness and performance requirements. The method is then applied to control an automotive powertrain system, whose dynamics are highly nonlinear. In particular, coordinating engine and transmission control variables to perform clutch-to-clutch shifts is illustrated. The design objectives are to provide smooth transients for passenger comfort and to reduce clutch energy dissipation requirements for component longevity. The robustness and performance characteristics of the designed controller are demonstrated for a case that involves neglected actuator dynamics, whose bandwidth is very close to the frequency of the controlled system dynamics.

Control system for use with anti-lock brake systems and anti-slip traction

Abstract: A control system for use with anti-lock brake systems and anti-slip control systems is described in which the existing mu is estimated from the drive torque and brake torque and the speed of the wheels. The difference of the mu values at successive calculation steps forms the actual value DELTA mu (k) of the control which is compared with a set variable epsilon ( epsilon = 0 or is smaller and positive). The control variable which is acquired in this process influences a control element which varies the brake pressure or the amount of fuel per time unit.

Vehicle engine control system

Abstract: This invention relates to a vehicle engine control unit suitable for use in an automobile When a step-on detection signal is outputted from accelerator pedal operation state detection means (81), first controlled variable setting means (82) sets the controlled variable of engine output regulation means (7) in accordance with a manipulated variable detection signal and when a step-on release detection signal is outputted from the accelerator pedal operation state detection means (81), second controlled variable setting means (86) receives the output of a constant speed driving speed designation signal from driving state designation means (83) and sets the controlled variable of the engine output regulation means (7) necessary for making the driving speed of a vehicle equal to a target speed on the basis of the driving speed detection signal from driving speed detection means (85) When an acceleration driving designation signal is outputted from the driving state designation means (83) described above, the second controlled variable setting means (86) sets the controlled variable of the engine output regulation means (7) necessary for the vehicle to make acceleration driving Particularly because the second controlled variable setting means (86) sets a controlled variable which serves to vary vehicle in accordance with the time and the vehicle speed, the speed change of the vehicle can be made smoothly through the engine output regulation means (7) operating on the basis of this controlled variable

An Integrated Configuration and Control Analysis Technique for Hypersonic Vehicles

Abstract: This paper describes a design analysis methodology for hypersonic vehicles that treats the vehicle configuration and trajectory simultaneously. Vehicle geometry, dynamic discontinuities, and time-dependent control variables are all treated as optimization parameters with respect to a single performance measure. A generalized first order gradient method is used to affect changes in the optimization variables to minimize a performance or cost measure. This is done while maintaining prescribed two-point boundary conditions and any path constraints imposed on the problem. The current research status and projected benefits of these activities are discussed.

Idling speed controller for engine

Abstract: PURPOSE: To prevent any increase of an idling speed variation at time of trouble happening by installing a trouble detecting means, detecting an abnormal state in an input signal attending on trouble or the like in a load sensor, and a learning compensation prohibiting means receiving this signal and stopping any operation of a learning compensating means at time of the trouble happening, respectively. CONSTITUTION: Basically, a load compensating means F compensates a controlled variable of a speed regulating means D and makes the specified speed so as to be maintained according to magnitude of external load by a load sensor G. Likewise, a learning compensating means H receives a signal of idling speed detected by an idling speed detecting means K, learning a control characteristic of the regulating means D from a state of, for example, the compensating means F or the like to this signal, and it performs such compensation as reflecting control afterward so as to cause the idling speed to become a specified state. On the other hand, when a trouble detecting means J detects an abnormal state in an input signal attending on throuble or the like the sensor G, a learning compensation prohibiting means L outputs a signal to stop its operation to the compensating means H, any increase of a speed variation attending on control instability due to mislearning is prevented from occurring. COPYRIGHT: (C)1990,JPO&Japio

A solution method for regular optimal control problems with state constraints

Abstract: A method of region analysis is developed for solving a class of optimal control problems with one state and one control variable, including state and control constraints. The performance index is strictly convex with respect to the control variable, while this variable appears only linearly in the state equation. The convexity or linearity assumption of the performance index or the state equation with respect to the state variable is not required.

Vehicle trouble detector

Abstract: PURPOSE:To enable easy detection of troubles of a vehicle by detecting them on the basis of the deviation between model control results and real control results based on a given control command. CONSTITUTION:A monitoring equipment 4 takes in not only data such as controlled variable and control target in a main control unit 2 but also various data indicating the operating state of a main motor 3 and the running state of a vehicle via sensors such as current sensor 5 and speed sensor 6 to prepare real control results A, B. Also, a model selection equipment 7 prepares model control results C, D on the basis of a control command given from a commander 1. When a deviation more than a given value appear between said real control results A, B and model control results C, D, a comparison circuit 8 emits an alarm and outputs a maintenance command.

Chapter 1 The Synergy of Voluntary and Involuntary Action

Abstract: Publisher Summary This chapter describes the synergy of voluntary and involuntary action. Voluntary acts being desired and intended beforehand are done with full prevision of what they are to be. Volitional actions are considered intended self-controlled inputs rather than emitted or elicited outputs. Man-made mechanisms that control their input, keeping the value of a monitored variable equal to an intended reference value by means of negative feedback, are called “control systems” or “closed-loop control systems.” Control systems are not necessarily homeostatic. The value of a controlled variable may “track” the value of a rapidly varying reference signal so precisely that they covary almost as if they were one and the same. In addition, control systems may employ proprioceptors to control variables such as posture, just as they employ exteroceptors to control the value of variables in an external environment. The operating principle remains the same: the control of input through negative feedback. In organisms, as in man-made control systems, volitional action is essentially an image →input process, not an organism → output process. Although control systems can be extremely complex, any system controlling a given parameter appears relatively simple when reduced to its basic canonical form. In its canonical form, the flow chart of any such system is a single negative feedback loop.

Improved optimum structural design by passive control

Abstract: The problem of optimum structural design by passive control is stated in a nonlinear programming form. A solution procedure, based on a successive selection of design and control variables, is presented. Neglecting the implicit analysis equations, the solution becomes independent of the control variables and a lower bound (LB) on the optimum can easily be obtained. The control variables are then selected to satisfy all constraints. If this cannot be achieved, the LB constraints are modified and the control variables are chosen for the revised optimal design. These two steps are repeated until the final optimum is reached.

Adaptive control method

Abstract: PURPOSE: To device a manipulated variable optimum to the characteristic change of a plant due to the lapse of time or the disturbance and to improve the controllability by using a model which simulates an entire multi-input/output plant as well as the nonlinear characteristic. CONSTITUTION: A control system consists of a target value estimation system 3 which estimates the target value (r) of the controlled variable (y) of a control subject 1, a model identification system 4 which identifies a nonlinear regression model of the subject 1, a controlled variable estimation system 5 which estimates the controlled variable (y) based on the identified regression model, and an estimated control system 2 which controls the subject 1 based on the estimated values (r) and (y). The system 4 identifies a model which obtains an estimated output variable of the subject 1 based on the time series signal of an input/output variable of the subject 1. The nonlinear regression model is attained by a neural circuit network, and a manipulated variable optimum to the characteristic change of a plant which is caused by the lapse of time or the disturbance. Thus the controllability is improved. Furthermore the operation data on the plant is applied to the learning of the neutral circuit network. Then a nonlinear regression model is identified in an on-line system to deal with the characteristic change of the plant due to the lapse of time or the disturbance. COPYRIGHT: (C)1991,JPO&Japio

Dynamic analysis and control of cancer

Abstract: A knowledge-based mathematical model is proposed for the interaction between tumor cells and the immune system. Parametric control variables relevant to the latest experimental data, i.e. sigmoidal dose-response relationship and Michaelis-Menten dynamics, are also considered. A model is composed of 12-state, first-order, nonlinear differential equations based on the cellular kinetics. Each of the states can be modeled as bilinear. The preliminary results show that the parametric control variable is important in the destruction of tumors. In addition, the exacerbation theory is a good method for tumor control. >

Repetitive control device

Abstract: PURPOSE:To always secure the stability of a control system by providing the title device with a sampling control circuit and setting up a sampling period in accordance with the repetitive period of an objective value or disturbance. CONSTITUTION:A subtractor 1 calculates a control deviation from an objective value (r) and a control variable from a control object 11 or the like and a deviation is sampled by a sampler 2. The sampling period is set up by repetitively executing the feedback control of the object 11 by a sampling period control circuit 12 for detecting a change in the period of the objective value (r) so that a deviation between an object value set up based upon the ratio of L to the level difference of a register to be a storage element 6 and a control variable is gradually reduced. Thereby, even when an objective value different from a designed value is applied, the stability of the control system can be always secured. In case of suppressing disturbance, a disturbance repeating period is used in stead of an objective value to obtain a result similar to be setting of the sampling period.

Generator optimum stabilizing control method

Abstract: PURPOSE:To enable conducting a stable control by performing an optimum control through incorporating a lag time by a control information transmission time and a control manipulated variable decision time in a control information structure expressing a dynamic relation between a plurality of state variables and a plurality of control variables of a controlled system CONSTITUTION:A generator excited governer multivariable optimum control system generates an equation of state on the basis of state variables and control variables such as a phase difference angle between generator systems delta, a generator angular velocity n, a field voltage VF, a generator input h, and a governor opening g Further, a state variable composed of a control information transmission time and a control manipulated variable decision time is introduced into said equation of state Then, the optimum control gain is decided on the basis of this state equation In this manner, stable dynamic characteristics can be obtained

Control device for variable capacity compressor

Abstract: PURPOSE:To obtain a control device for a variable capacity compressor having excellent control properties by providing an auxiliary control means supplementing the drive of a capacity varying mechanism for a compressor corresponding to a judging means judging the variation of control variables. CONSTITUTION:The capacity of a variable compressor 10 is controlled by a capacity control means depending on the thermal loading of refrigerating cycle. On the other hand, it is judged by a Judging means that the capacity of a variable compressor 10 is controlled by a control means, that is, the wobble plate 10d of a swash plate type compressor is driven. Then, the frequency of current driving a solenoid valve 10o is lowered corresponding to the aforesaid judgement so as to let the pressure in a crank room 10c be fluctuated for facilitating the movement of the wobble plate 10d.