Showing papers on "Control theory published in 1982"

Articulated Hands: Force Control and Kinematic Issues

Abstract: Kinematic and control issues are discussed in the context of an articulated, multifinger mechanical hand. Hand designs with particular mobility properties are illustrated, and a definition of accuracy points within manipulator workspace is given. Optimization of tlte physical dimensions of the Stanford-JPL hand is described. Several architectures for position and force control of this multiloop mechanism are described, including a way of dealing with the internal forces inherent in such systems. Preliminary results are shown for the joint torque subsystem used in the hand controller.

Stable model reference adaptive control in the presence of bounded disturbances

Abstract: The adaptive control of a linear time-invariant plant in the presence of bounded disturbances is considered. In addition to the usual assumptions made regarding the plant transfer function, it is also assumed that the high-frequency gain k p of the plant and an upper bound on the magnitude of the controller parameters are known. Under these conditions the adaptive controller suggested assures the boundedness of all signals in the overall system.

Design of feedback control systems

Abstract: From the Publisher: Design of Feedback Control Systems is designed for electrical and mechanical engineering students in advanced undergraduate control systems courses. Now in its fourth edition, this tutorial-style textbook has been completely updated to include the use of modern analytical software, especially MATLAB. It discusses classical control theory and state variable control theory, as well as advanced and digital control topics. Each topic is preceded by analytical considerations that provide a well-organized parallel treatment of analysis and design. Design is presented in separate chapters devoted to root locus, frequency domain, and state space viewpoints. Treating the use of computers as a means rather than as an end, this student-friendly book contains new "Computer-Aided Learning" sections that demonstrate how MATLAB can be used to verify all figures and tables in the text.

Quantitative feedback theory

Abstract: In quantitative feedback theory, plant parameter and disturbance uncertainty are the reasons for using feedback. They are defined by means of a set Q = {P} of plant operators and a set D = {D} of disturbances. The desired system performance is defined by sets of acceptable outputs A u in response to an input u, to be achieved for all Pϵ Q. If any design freedom remains in the achievement of the design specifications, it is used to minimise the effect of sensor noise at the plant input. Rigorous, exact quantitative synthesis theories have been established to a fair extent for highly uncertain linear, nonlinear and time-varying single-input single-output, single-loop and some multiple-loop structures; also for multiple-input multiple-output plants with output feedback and with internal variable feedback, both linear and nonlinear. There have been many design examples vindicating the theory. Frequency-response methods have been found to be especially useful and transparent, enabling the designer to see the trade-off between conflicting design factors. The key tool in dealing with uncertain nonlinear and multiple-input multiple-output plants is their conversion into equivalent uncertain linear time-invariant single-input single-output plants. Schauder's fixed-point theorem justifies the equivalence. Modern control theory, in particular singular-value theory, is examined and judged to be comparatively inadequate for dealing with plant parameter uncertainties.

System for controlling power distribution to customer loads

Abstract: A method and apparatus which permits a power utility to have direct control of customers loads (CD) with a view toward facilitating enablement of a load management philosophy which includes peak shaving and load deferral. A master control station (MCS), which comprises a programmable microprocessor-based central controller, is in two-way communication with a plurality of substation injection units (SIU), one of each of which is positioned at a separate substation of the power utility. Each substation injection unit (SIU), under the control of its own microprocessor, responds to master control signals from the master control station (MCS) to inject a pulse code signal onto the power lines of the utility. The system includes a plurality of remote receiver units (RRU) which are positioned at and connected to control the on and off times of customer loads (CD). Each remote receiver unit (RRU) is preset to respond to particular pulse code signals from the substation injection units (SIU) to carry out the desired command functions, which can be implemented either automatically or manually on a fixed or dynamic-cycle basis as the need arises. The system utilizes a command signal and pulse code signal verification technique to insure system integrity and reliability.

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.

Variable Structure Control of Electric Power Generation

Abstract: A control scheme to reduce the mismatch in power generation and consumption of electric power systems is developed using the variable structure systems concept. This scheme is introduced to refine the dynamic properties of the presently used integral controller which has been originated in accordance with a steady state concept. The new controller changes its structure according to a certain logic which results in distinct advantageous properties.

A parameter adaptive control structure for linear multivariable systems

Abstract: This paper presents an adaptive control structure which can be used to assign all poles and zeros of a continuous-time linear multivariable system represented by an ( m \times m ) strictly proper transfer matrix T(s) , provided T(s) has no right-half plane zeros. The controller parameters can be directly estimated from input-output data. The paper also serves to point out the type of a priori information necessary for multivariable adaptive controller design. This information is a natural extension of that required in the scalar case.

Remote control for motor vehicle

Abstract: A remote controller is disclosed for controlling the throttle, brake and steering mechanism of a conventional motor vehicle, with the remote controller being particularly advantageous for use by severely handicapped individuals. The controller includes a remote manipulator which controls a plurality of actuators through interfacing electronics. The remote manipulator is a two-axis joystick which controls a pair of linear actuators and a rotary actuator, with the actuators being powered by electric motors to effect throttle, brake and steering control of a motor vehicle adapted to include the controller. The controller enables the driver to control the adapted vehicle from anywhere in the vehicle with one hand with minimal control force and range of motion. In addition, even though a conventional vehicle is adapted for use with the remote controller, the vehicle may still be operated in the normal manner.

Self-Tuning Regulators for Multicyclic Control of Helicopter Vibration

Abstract: A class of algorithms for the multicyclic control of helicopter vibration and loads is derived and discussed. This class is characterized by a linear, quasi-static, frequency-domain model of the helicopter response to control; identification of the helicopter model by least-squared-error or Kalman filter methods; and a minimum variance or quadratic performance function controller. Previous research on such controllers is reviewed. The derivations and discussions cover the helicopter model; the identification problem, including both off-line and on-line (recursive) algorithms; the control problem, including both open-loop and closed-loop feedback; and the various regulator configurations possible within this class. Conclusions from analysis and numerical simulations of the regulators provide guidance in the design and selection of algorithms for further development, including wind tunnel and flight tests.

On eigenstructure assignment in linear multivariable systems

Abstract: The eigenvalue-assignment approach of Brogan [1], [2] is generalized and extended to the assignment of the entire closed-loop eigenstructure of linear multivariable systems The set of assignable eigenvectors and generalized eigenvectors emerges naturally in the solution and is given, moreover, in an explicit parametric form Two numerical examples are worked out to demonstrate the application of the procedure

A new design of constrained controllers for linear systems

Abstract: A new method is presented to find stabilizing saturated linear state feedback controllers for linear continuous-time and discrete-time systems. A controller of this type was satisfactorily tested on board a submarine as a depth regulator.

An innovations approach to dual control

Abstract: The control of a stochastic system with unknown parameters is considered. A novel cost function which includes the variance of the innovations process is used to optimize the performance of the system. The cost function has two parts. One that reflects the goal of regulating the output, and the second one that reflects the need to gather as much information as possible about the parameters of the system, the latter being represented by the variance of the innovation process. The control law derived has an explicit solution that allows for an easy implementation, and has dual properties. The relationships among the controller obtained in this paper and the certainty equivalence and cautious controllers are analyzed. Simulation results show the quasi-optimal performance of the new controller.

Zoned control system

Abstract: In this thermal system there is a central plant feeding a plurality of adjustable zone regulators which bring their respective zones to corresponding target temperatures. The system has a controller including a plurality of temperature sensors. The sensors are distributed one to a zone. Each of the sensors can produce a zone signal signifying zone temperature. The controller also has a plurality of zone actuators, each having a zone control terminal. Each of the actuators can, in response to a signal at its zone control terminal, adjust a corresponding one of the zone regulators. Also included is a control subsystem that is coupled to each of the temperature sensors and to the zone control terminal of each of the zone actuators. The control subsystem can start the central plant in response to a predetermined function of the zone temperature errors with respect to their respective target temperatures exceeding a given limit. The control subsystem can also apply corresponding signals to each zone control terminal, with a timing determined by its corresponding temperature error.

Image recording method and apparatus

Abstract: A method and apparatus utilizing a controller having a plurality of openings or slit-like openings to control the passage of charged particles and to record a visible image by the charged particles directly on an image receiving member. The present invention is an improved device for supplying the charged particles to a control electrode and has made high-speed and stable recording possible. The improvement lies in that the charged particles are supported on a supporting member and an alternating electric field is applied between the supporting member and the control electrode. Thus, it has become possible to sufficiently supply the charged particles to the control electrode without scattering them.

Automatic control of blood pressure by drug infusion

Abstract: Automatic control of arterial blood pressure by infusing the drug sodium nitroprusside is used for the treatment of elevated blood pressure after open-heart surgery at the Cardiac Surgical Intensive Care Unit of the University of Alabama Hospital. Controller design was based on investigations of the dynamics of the physiological responses of patients to nitroprusside infusion. A nonlinear PID digital controller has been used on over 1700 patients. Clinical experiences have shown that automatic control is safe and effective. The wide range of patient characteristics we have observed warranted the design of an improved controller.For analysis, design and evaluation, a model of the system related to arterial pressure and its response to nitro prusside was developed, and patient care practices were analysed. An adaptive multiple-mode multirate sampled-data controller was designed using model-based techniques, and was implemented with a microcomputer system. Simulation results were verified by experiments in the animal laboratory. Results from clinical evaluations with postsurgical patients were superior to the performance of previous automated infusion systems.

An adaptive LQ controller for non-minimum-phase systems†

Abstract: The paper studied the problem of the adaptive tracking of a reference signal by the output of any deterministic discrete SISO linear system with unknown parameters. An adaptive control scheme, based on the LQ control solution, is proposed. The stability of the resulting adaptively controlled system and conditions for a good tracking are studied. Several simulations illustrate the proposal.

Fluid flow control system

Abstract: A fluid flow control system includes a weight detector (12), for generating a weight measurement signal that is indicative of the weight of fluid in a reservoir (11); an adjustable reference generator (14) for generating a weight reference signal that is indicative of the desired rate of decrease in weight of the fluid in the reservoir (11); and a comparator (13) that produces an output indicative of the dissimilarity between the weight measurement and the weight reference signals. In a preferred embodiment, a drop counter (21) is placed in the line of flow (16) from the reservoir (11). The drop counter (21) produces an actual drop rate signal. There is also provided a device (22) that generates a programmed drop rate signal. The programmed drop rate signal is modified by the previously described comparator's output to produce a corrected drop rate signal. The actual and the corrected drop rate signals are directed to a second comparator (23) that operates on a flow controller (15).

Hybrid adaptive control of continuous time systems

Abstract: In this note a method is presented for doing discrete adaptive control of continuous time systems. Rather than make the entire compensator discrete, the compensator is separated into a continuous time adjustable control structure and a discrete time adaptation mechanism for updating the controller parameters. The discrete adaptation algorithm which randomly samples filtered versions of the plant input and output signals, and periodically updates the controller parameters, is shown to produce a stable closed loop system for any average sampling rate.

Design of model-following servo controller

Abstract: A servo controller is designed so that the step response of the plant is as close as possible to that of a model system while the output regulation condition is satisfied. The controller is named "the model-following servo" and its control law is determined by optimization. The associated algorithm is presented. An example is included to illustrate the procedure.

Virtual machine control

Abstract: The present invention is an electronic controller that is partially a virtual machine. The virtual machine portion of the controller comprises an Operating System including two major levels--namely, an Instruction Module level and a Primitive level. Directives corresponding to macros in a physical machine (microprocessor) architecture are the top level of the control. The Directives shield the Operating System structure from changes in the compiler, allow for changes in the Operating System internal structure and abstract out from the compiler unnecessary operating system details. Instruction Modules and Primitives make up the Operating System. Instruction Modules are the middle level and correspond to assembly language instructions in a physical machine. They are the smallest executable, nonpreemptive unit in the virtual machine. Preemption is similar to a physical machine interrupt capability except that a physical machine allows basically two concurrent processes or tasks (foreground or background) whereas the virtual machine allows an almost unlimited number of tasks executing in one or more physical processors.

Robot arm controller with common bus memory

Abstract: In a robotic apparatus having a manipulator arm including plural motors to move the arm to predetermined spatial positions and a control system for the arm, a common bus and common memory connected to the bus. The control system comprises respective microprocessor based controllers for each of the joints, microprocessor based computation means for performing the mathematical computation to control the trajectories of the arm and common microprocessor based coordinating control system for coordinating the activities of the other modular microprocessor based control system. Accessing routine is associated with the bus for providing each of the microprocessor based control system with direct, exclusive access to the bus during respective time intervals. The common memory serves as a depository for messages to and from the microprocessor based control system to enable intercommunication between the microprocessor based control system accessing the bus.

Optimized selection of dissimilar chillers

Abstract: A system for meeting building air conditioning load conditions by optimally selecting a combination of chillers having dissimilar efficiency characteristics, the system having a load sensor for sensing building load a refrigerant head sensor for sensing refrigerant head of the chillers, and a controller connected to the load sensor and to the refrigerant head sensor for sorting the chillers according to their efficiency characteristics data with the chiller having a minimum kw/ton versus capacity point being ranked first and for selecting a combination of the chillers which will require a minimum energy input to meet building load conditions.

Optimal adaptive controllers for unknown Markov chains

Abstract: We consider the problem of adaptively controlling an unknown Markov chain. No prior information regarding the values of the transition probabilities is provided us (except for a list of forbidden, zero-probability transitions, which is usually obtained as a byproduct of the modeling process itself). The goal is to design an adaptive controller to adequately control the unknown system when its performance is measured by the average cost incurred over a long operating time period. Our main result is the exhibition of a family of adaptive controllers which, when applied to the unknown system, will result in a performance precisely equal to the optimal performance attainable if the system, i.e., the transition probabilities, were known. Hence, the adaptive controllers proposed here are truly optimal, even when operating on an unknown system. The results presented here extend similar results in [1] where we assume to be initially provided with a finite set of possible models, one of which is guaranteed to be the true one. This paper directly addresses those practical situations where a finite set of possible models with such a guarantee is hard to come by.

Programmable controller with back-up capability

Abstract: An active programmable controller services I/O racks which contain circuits that interface with sensing devices and operating devices on a machine being controlled. A back-up programmable controller monitors this I/O data to maintain a current I/O image table in its memory. Other status data is coupled to the back-up controller from the active controller through a peer-to-peer communications link. If a malfunction occurs in the active controller, the back-up controller is signaled to switch to the active mode in which it assumes control of the operating devices on the machine being controlled.

Analysis of a Finite Storage System with Batch Input Arising out of Message Packetization

Abstract: A Markovian queueing model with finite waiting space is developed for the communications controller which buffers the flow of packets from a host computer to its associated packet switch. The segmentation of messages into packets by the host is modeled by a batch input to the communications controller. The probabilities of state are determined by numerical recursion and subsequently used in expressions developed for the blocking probabilities and waiting-time distribution as a function of two proposed batch acceptance strategies. Representative numerical results as would be useful in the dimensioning and performance analysis of the communications controller are presented. A more general non-Markovian model is investigated by means of simulation, showing that the initial Markovian model is very accurate in determining the system performance.

Brushless ultra-efficient regenerative servomechanism

Abstract: A servomechanism regeneratively controls motion by a brushless coreless axial-field motor, exerting torque thru its permanent-magnet disk rotor, resulting from synchronized polyphase sinusoidal stator currents, controlled by a switching controller responsive to input commands and to Hall-effect transducer signals that vary sinusoidally with rotor angle and respectively correspond to stator phases. The controller operates with a dc power source and sink. Its signal processors derive from the transducer signals instantaneous magnitudes and polarities thereof and continuous lagless speed feedback. The instantaneous magnitudes are multiplied by a torque amplitude signal to provide respective synchronized amplitude control signals. Current transformers having primary windings in series with power switching transistors provide current feedback pulses with amplitude proportional to instaneous current in associated stator windings. Pulse control means initiate bi-phase pulses having restricted duty-cycle, and dictate pulse duration by comparing each current feedback pulse with the associated synchronized amplitude control signal. Switching logic responsive to the bi-phase pulses, to forward and reverse drive and brake commands, and to said polarities, accordingly controls selection and duty-cycle of said power switching transistors which, cooperative with free-wheeling diodes and inductors, effect controlled alternating stator currents. Various signal interface means process the input commands with feedback derived from the transducer signals, such as speed, direction of rotation, and interpolated digital position, to provide said torque amplitude signal, and variously, said drive and brake commands; so the motor and controller constitute a complete servomechanism, that provides precise speed and position control with regenerative reversing and braking, ultra-high efficiency, and fast dynamic response.