Boots – shoes – and leggings
Patent
1989-02-14
1991-08-06
Smith, Jerry
Boots, shoes, and leggings
364151, G05B 1302
Patent
active
050382691
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to industrial control systems.
BACKGROUND OF THE INVENTION
Industrial control systems are used to control a wide variety of industrial processes. Examples of such processes include the control of steel rolling mills (to maintain uniform output thickness of rolled steel strip), ship stabilization, dynamic ship positioning, adaptive ship autopilots, temperature control of buildings, radio aerial tracking, and a wide variety of chemical processes.
In all such processes, the problem in general terms is to maintain a desired quantity (such as the heading of a ship) constant (or following a desired pattern) in the face of peculiarities of the apparatus itself (such as slow response time of the rudder in turning to a desired position, and of the ship in turning in response to a rudder position change) and external influences (such as steady cross currents and varying wind forces). The control system (controller, actuators, and sensors) measures the desired quantity and generates a control signal which is fed into the system being controlled (as a control signal to the rudder position gear).
The controller can be regarded, in mathematical terms, as calculating the control signal as some function of the measured quantity. The particular function chosen can generally be regarded as a transfer function having a particular form (e.g. a polynomial of given degree) and having particular parameters (which would then be the coefficients of the various terms of the polynomial). The form of the function is chosen from a knowledge of the general characteristics of the system to be controlled. The parameters of the chosen form can then be determined in various ways, involving measurement or calculation of the characteristics of the system to be controlled.
In many control systems, the controller parameters are fully defined by the initial design, and the controller provides satisfactory control. However, in some systems, the operating conditions and/or system characteristics vary widely with time; for example, the characteristics of a cargo ship will differ widely depending on its speed, whether it is fully laden or in ballast, etc. In such circumstances, it may be desirable for the control system to be adaptive. For that, the characteristics of the system are monitored and the parameters of the controller are adjusted accordingly. Thus the control system does not merely calculate the control signal in dependence on the measured quantity; it also adapts itself to changes which are detected in the general characteristics or behaviour of the system being controlled by continual parameter adjustment.
One known controller design technique is known as H.infin. (H-infinity) design. This has various advantages, but it has the drawback that the calculations involved in determining an H.infin. controller in any particular instance are in general very complicated and involved. The H.infin. method has therefore generally been used for the initial (off-line) design of controllers.
BRIEF SUMMARY OF THE INVENTION
The main purpose of the present invention is to provide a control system which is of the H.infin. type (in a sense discussed in detail later) and which is sufficiently simple in the calculations involved for the controller calculations to be carried out in an on-line system. As explained above, such a system is an adaptive system, because the controller is being updated regularly.
Accordingly the present invention provides an industrial controller for controlling an industrial process, comprising a controller unit fed with a reference signal (r) and the output (y) of the process, a parameter estimator fed with the output (u) of the controller unit and the output (y) of the process and producing estimated polynomials A, B, and C, and a controller design unit fed with A, B, and C and feeding the controller unit with coefficients for implementing a polynomial ratio control function (C.sub.n /C.sub.d), characterized in that the controller design unit comprises means for stori
REFERENCES:
patent: 4578747 (1986-03-01), Hideg et al.
patent: 4639853 (1987-01-01), Rake et al.
patent: 4641235 (1987-02-01), Shigemasa et al.
patent: 4674028 (1987-06-01), Shioya et al.
patent: 4774667 (1988-09-01), Kuraoka et al.
patent: 4791548 (1988-12-01), Toshikawa
patent: 4879643 (1989-11-01), Chakravavty et al.
patent: 4882526 (1989-11-01), Iino et al.
International Journal of Control vol. 46, No. 4, Oct. 1987, Grimble, N.J.:"Infinity Robust Controller for Self-Tuning Control", pp. 1429-1444.
M. J. Grimble, "Infinity Robust Controller for Self-Tuning Control Applications, Part 2, Self-Tuning and Robustness", International Journal of Control, vol. 46, No. 5, Nov. 1987, pp. 1819-1840.
Hwang et al., "Adaptive Control of Optimal Model Matching in H-Infinity-Norm Space", IEEE Proceedings, vol. 135, No. 4, Jul. 1988, pp. 295-301.
Fairbairn Niall A.
Grimble Michael J.
National Research Development Corporation
Smith Jerry
Trammell Jim
LandOfFree
Industrial control systems does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Industrial control systems, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Industrial control systems will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1991608