Showing papers on "Control theory published in 1977"

Nonlinear Control Engineering

Abstract: Nonlinear control engineering , Nonlinear control engineering , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی

Light-weight program controller

Abstract: A control system for programming operations of a spraygun robot for spraying paint comprises a mobile control structure having jointed parts of the robot, and also possesses transducers corresponding to transducers of the robot, for transforming electrical signals respectively from and into operations of the mobile structure and of the robot. The control structure is relatively light and mobile to facilitate manual operation. The robot is sufficiently massive and heavy to permit numerous operations of the joint devices thereof in a point-spray atmosphere.

Linear estimation and stochastic control

Abstract: Linear estimation theory. Hilbert space. Stochastic processes. Hilbert space. Othogonal increments processes. Linear stochastic control. Dynamic programming. Stochastic linear regulator. Separation principle.

Adaptive control of single-input, single-output linear systems

Abstract: A procedure is presented for designing parameter-adaptive control for a single-input, single-output process admitting an essentially unknown but fixed linear model, so that the resulting closed-loop system is globally stable with zero steady-state tracking error between the output of the process and the output of a prespecified linear reference model. The adaptive controller is a differentiator-free dynamical system forced only by the process input and output, as well as by a reference input.

Levels, hierarchies, and the locus of control

Abstract: The Bartlett–-Craik view of human performance is restated; and particularly that it is organised at different levels On that view, the lower levels are controlled by the upper but capable of functioning independently Modern views of memory, language, and problem-solving are compared with this doctrine, and found to embody some of its virtues but not all Fresh experiments are described, in which people take decisions about the running of a transportation system The simplest control mechanism which will model their behaviour is a two-level adaptive controller Text of the Sixth Sir Frederick Bartlett Lecture given at a meeting of the Experimental Psychology in London, 7 January 1977

A design technique for linear multivariable feedback systems

Abstract: A systematic approach is developed for the design of linear multivariable feedback control systems based on a manipulation of the set of frequency-conscious eigenvalues and eigenvectors of an open-loop transfer-function matrix. The key idea behind the approach used is that of an approximately-commutative controller. An algorithm for approximation of a frame of complex vectors by a frame of real vectors is developed and plays a basic role in the systematic design approach. An example, based on industrial plant data, is given showing how the design method is used.

An adaptive optimal controller for discrete-time Markov environments

Abstract: This paper describes an adaptive controller for discrete-time stochastic environments. The controller receives the environment's current state and a reward signal which indicates the desirability of that state. In response, it selects an appropriate control action and notes its effect. The cycle repeats indefinitely. The control environments to be tackled include the well-known n -armed bandit problem, and the adaptive controller comprises an ensemble of n -armed bandit controllers, suitably interconnected. The design of these constituent elements is not discussed. It is shown that, under certain conditions, the controller's actions eventually become optimal for the particular control task with which it is faced, in the sense that they maximize the expected reward obtained in the future.

The hydraulics of rotating-channel flow

Abstract: Flow of a homogeneous inviscid fluid down a rotating channel of slowly varying crosssection is considered, with particular reference to conditions under which the flow is ‘hydraulically controlled’. This problem is a member of a general class of problems of which gas flow through a nozzle and flow over a broad-crested weir are examples (Binnie 1949). A general discussion of such problems gives the means for determining the position of the control section (which is generally flow dependent) and shows that at this position there always exist long-wave disturbances with zero phase speed (i.e. disturbances are always ‘critical’ at the control section). The general theory is applied to the rotating-channel problem for the case of uniform potential vorticity. For this problem, three parameters are needed to specify the upstream flow, and the control theory gives a relationship between these parameters which depends on the geometry of the channel.

Programmable human tissue stimulator

Abstract: An implanted heart and tissue stimulator is provided which is externally programmable so that stimulating signals generated thereby can be changed to meet the changing requirements of the user. Provision is made for verifying and screening control parameter words which are transmitted from an external controller so that only correct parameters will be stored for use by the implanted stimulator. Provision for read out of stimulating signals and of the tissue response thereto is also provided.

Digital processing and calculating ac electric energy metering system

Abstract: A metering system for electric utility power line measurements includes voltage and current signal inputs that are randomly sampled and converted to binary representations. A system sequence controller and calculator provides programmed control for processing digital control and data signals and for producing digital calculations of electric energy parameters from the binary representations of the instantaneous signal values. Memory registers totalize and accumulate digitally calculated values for producing visual displays and output signals that correspond to electric energy parameters to be measured.

Some interpretations of the self-tuning controller

Abstract: The self-tuning controller is extended to include rational transfer function (as opposed to polynomial) terms in the associated cost function. Two interpretations of the self-tuning controller are examined in some detail: a model reference adaptive control, and a self-tuning least-squares predictor in conjunction with conventional compensation. The former version is shown to give not only prespecified set point response, but also a closed-loop disturbance with largely prespecified spectral density. The latter version is compared with the method of O.J.M. Smith, and is shown to be less sensitive to uncertainty in some system parameters. Examples are given which illustrate the continuous-time performance of these discrete-time control laws.

Fuel control system with calibration learning capability for motor vehicle internal combustion engine

Abstract: A memory type fuel control system and method of operating a motor vehicle internal combustion engine having a three-way catalytic converter. A fuel flow control system provides a fuel supply rate near the air/fuel ratio at which the catalytic converter has maximum three-way conversion efficiency. The fuel supply rate so determined is trimmed by a trim factor recalled from memory, the authority of this trim factor being sufficient to compensate for engine and controller variations with time, manufacturing tolerances, etc. In the preferred form, the trim factor is stored in memory at an address determined by the same engine operating conditions that control the fuel supply. The engine exhaust gas oxidizing/reducing conditions are sensed by exhaust gas sensors. In the preferred form, a closed loop controller is responsive to the deviation of the sensed oxidizing/reducing conditions from the condition at which the catalytic converter has maximum three-way conversion efficiency to adjust the trimmed fuel supply rate in a sense to produce the oxidizing/reducing condition at which the maximum conversion efficiency is obtained. A sampling circuit recurrently samples and momentarily stores the engine operating conditions, such as engine load and speed conditions, in a short term memory to form a history of those conditions extending back at least by the amount of the engine transport delay time. At a later time, the exhaust gas oxidizing/reducing conditions sensed by the exhaust gas sensor is sampled, the engine operating conditions that produced the sampled exhaust gas condition are recalled from the short term memory, a new trimming value is determined for the recalled vehicle conditions which more closely produce a desired oxidizing/reducing condition, and such value is inserted in the main memory at the address determined by the recalled conditions. Such trim factor is then available for recall and use as the trimming factor when the engine is next operated under such conditions.

An Electrohydraulic Knee-Torque Controller for a Prosthesis Simulator

Abstract: A new approach for evaluating advanced concepts for knee-joint control in above-knee prostheses involves the use of a simulator prosthesis which can be worn by an amputee and controlled electronically to emulate proposed future prostheses. A critical element in this system is the knee-torque controller. Realization of a powerful, lightweight, easily controlled transducer was essential to the successful development of the simulator system. This paper presents the design of such a controller and evaluates its performance. Brief examples of studies in which the new system has been applied are given. The proven viability of the device suggests that similar actuators might aid other prosthesis/orthesis studies.

A Heuristic Model for the Human Vergence Eye Movement System

Abstract: A heuristic feedback system model for the human disparity-vergence eye movements is described. The system has been modeled as a continuous negative feedback system with a modified integral-derivative controller, a time-delay element, and a third-order plant. Simulation studies of the model responses for both step and sinusoidal responses fit the experimentally obtained results.

Process control system with backup process controller

Abstract: A process control system having a backup controller which is substituted for one of a plurality of primary process controllers upon the detection of a failure of one of the primary process controllers. The substitution of the backup controller is controlled by a backup director which is arranged to sense the operation of a primary process controller and to transfer the operating data from the failed controller into the backup controller to enable the backup controller to take over the operations being performed by the failed controller.

Extended Energy Management Methods for Flight Performance Optimization

Abstract: This paper develops a singular perturbation approach to extend existing energy managment (EM} methods. A procedure is outlined for modeling altitude and flight path angle dynamics which are ignored in EM solutions. It is shown that nonlinear feedback solutions can be obtained, even for EM problem formulations which currently result in a two-point boundary-value problem. A nonlinear controller for two-dimensional, minimum time aircraft climbs is derived and numerical results for a fighter aircraft are given. The procedure outlined in this paper is general and applicable to solving a wide class of optimal control problems. It avoids the problem of picking the unknown boundary conditions at the initial and terminal times to suppress the unstable modes in the boundary layer.

Theoretical Considerations of Violent Marriages

Abstract: Personality characteristics of wife abusers who are termed the controller, the defender, the approval seeker, and the incorporator are described

Control Theoretic Models of Human Drivers in Car Following

Abstract: This paper is concerned with mathematical models of the control behavior of human drivers while following another vehicle in single lane traffic The emphasis is on the representation of the individual driver, rather than on such abstract parameters of multi-lane traffic as average density or average velocity Three basic types of approaches to representing the driver's control strategy are reviewed First is a classical control structure in which assumptions concerning the stimulus-response characteristics of the driver are included, and a form for his control strategy algorithm is assumed The second class of models is based on optimal control theory The major feature of this class of models is that an assumed performance index is explicitly included in the formulation, so that the driver's control strategy arises as a result of his attempts to minimize this index or criterion The third class of models reviewed in the paper are heuristic models, which arise from control theory The first of these, ter

Vehicle-Follower Longitudinal Control for Automated Transit Vehicles

Abstract: In this paper basic considerations in longitudinal control for small automated transit vehicles operating at moderate speeds and short headways are examined. The objective of this paper is the evaluation of control system designs applicable to vehicles using a linear induction motor (LIM) for propulsion and braking. Evaluation is based on dynamic response during nominal and emergency operations, sensing and communication requirements, and simplicity of controller design. The study is restricted to the vehicle-follower control concept. Basic control philosophies and spacing policies and their implications are discussed. Mathematical models of the vehicle and LIM are developed. Since the LIM is a highly nonlinear device, linear design procedures can be used to develop qualitative controller designs but computer simulations are necessary to establish numerical values for control system gains. The dynamic response of velocity and spacing controllers during various modes of operation are examined and controllers are designed for a variety of data sensing and transmission requirements.

A Hierarchical Approach to the Control of a Prosthetic Arm

Abstract: A hierarchical method combining analytical techniques from control theory and heuristic techniques from artificial intelligence is presented and applied to the decentralized control of a prosthetic arm. The dynamic model of the arm is derived, and two complementary performance criteria are suggested for the kinematic and the dynamic evaluation for the system response. The "principle of minimum interaction" is used to decompose the prosthetic system into seven subsystems, one per mechanical degree of freedom. A "suboptimal" control structure for nonlinear systems is proposed in conjunction with a performance adaptive self-organizing control algorithm. Syntactic pattern classification is used for the dynamic coordination of the subsystems. The syntax of the man-machine commands is also examined as part of the function of highest level of the hierarchy, the organizer.

Flank wear model of cutting tools using control theory.

Abstract: A model of the flank wear of cutting tools is developed by using linear control theory. The flank wear is assumed to consist of a mechanically activated and a thermally activated component. The wear process is mathematicall y treated as a feedback process, whereby the progressive wear raises the cutting forces and temperature thereby increasing the thermally activated wear-rate, and contributes to the mechanically activated wear. A mathematical expression for the flank wear growth is derived and shown to be consistent with experimental results. The experimental data is fitted to the wear model for calculat­ ing the mechanical wear coefficient and activation energy for the thermally activated wear. The model yielded a new tool-life equation which is valid over a wider range of speed than Taylor tool-life equation.

Two axes controller

Abstract: A two axis controller for controlling a tanker aircraft in-flight refueling boom while maneuvering prior to engagement with the receiver aircraft and including a boom load alleviation system after engagement Movement of the control stick is transmitted mechanically to a position transducer The transducer provides a signal to an actuator to effect boom control The transducer output is also transmitted to a servo motor which is mechanically connected to the control stick During the free flight mode, when the operator is manually controlling the boom, the servo motor provides a resisting force to stick movement that varies as a function of the transducer signal Following coupling of the two airplanes, which initiates the automatic load alleviation system, the same servo motor back drives the control stick in response to boom force and position signals to alleviate boom forces Manual override of the automatic system is possible at any time

Rate control system for manipulator arms

Abstract: A manipulator system having a master control console and a slave mainpulator arm controlled by signals from the master control console is disclosed The master control console includes a translation controller and a rotation controller, and the slave manipulator arm includes pivoted arm segments moved by translational servos in response to signals generated by the translation controller and pivoted wrist units moved by rotational servos in response to signals generated by the rotation controller The slave manipulator arm has six degrees freedom of movement defined as three translational degrees of freedom in range, azimuth and elevation and three rotational degrees of freedom in wrist pitch, yaw and roll The signals generated by each of the translation controller and the rotation controller are rate command signals The translational servos compare commanded range, azimuth, elevation or attitude rate with the actual range, azimuth, elevation or attitude rates of the slave manipulator arm Attitude rate error signals are generated and related to manipulator applied forces Similarly, the rotational servos compare commanded wrist pitch, yaw and roll rates with actual wrist pitch, yaw roll rates of the slave manipulator arm Wrist rate error signals are generated and related to manipulator applied torques Thus, when in contact with an object, no forces or moments are produced unless the rate controllers are deflected and held, the magnitude of the applied forces and moments being proportional to controller displacement The computed forces fromthe translational servos and the computed torques from the rotational servos are displayed on the master control console to provide visual force and torque feedback to the operator