Patent EP0649191A1 successfully refreshed from Google Patents.
Patent EP0462815A2 successfully refreshed from Google Patents.
EP0462815A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Receding horizon based adaptive control having means for minimizing operating costs
Assignee: Honeywell Inc
•
Filing: 1991-06-19
•
Granted: —
•
Expires: 2011-06-19
Abstract
Abstract An adaptive and predictive controller has self tuning capabilities, the receding horizon window and sample interval being determined by the tuning mechanism automatically, based on the relationship between the controlled and manipulated variables. The interval and window may be set by the user as well. Constraints on the manipulated and controlled variables at the end of the horizon window are accommodated automatically. In addition to providing servo regulatory control the controller simultaneously minimises operating costs. <IMAGE>
Inventors
- 👤 J. Ward Macarthur
- 👤 Michael A. Woessner
- 👤 David A. Wahlstedt
- 👤 Wendy K. Foslien
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-04 12:20
CPC Classifications
G; G05; G05B; G05B13/00; G05B13/02; G05B13/0205; G05B13/026
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
235 words
A controller for controlling the manipulated variable inputs to a plant to achieve a desired controlled variable output trajectory which is sensitive to the outputs from said plant wherein said controller receives user input and provides output signals to effect control moves wherein said controller establishes a model identification based on the manipulated variable inputs and the controlled variable outputs from the plant, said controller characterised by: a tuner (23) for establishing a control sample rate and for establishing the first m increments of a horizon window which has a total of m+l increments and a control law calculator means (25, 26) having a recursive model based predictor to predict the nominal control variable output trajectory that would occur without changes to the manipulated variables, said predictor deriving its model from the identified model, and having a model based corrector, also based on the same identified model, to specify the changes required of the manipulated variable outputs to satisfy the following criteria: a) the errors between the controlled variables and their respective setpoints become zero after m control moves b) the errors between the controlled variables and their respective setpoints are zero for l additional control moves c) the change in the manipulated variables during the last n control moves of the m+l horizon take on their prescribed beta values said specified manipulated variable changes being used to determine the output signals for the actuators.
Claim 2
Dependent Claim
99 words
A controller according to Claim 1 characterised in that said controller further comprises: optimizer calculator means (28) for providing manipulated variable sequences that results in optimal cost performance without compromising servo-regulatory performance having: access means for using the control law calculator (25) such that the predictor can be used to predict the effect on the plant as would be measured by the outputs of any hypothetical change made in any manipulated variable, calculator means for determining the optimal set of manipulated variable changes during the horizon window based on the predicted effects of the changes over the horizon window.
Claim 3
Dependent Claim
53 words
A controller according to Claim 1 or 2 characterised in that the tuner (23) further comprises a heuristic supervisor which receives plant output information and manipulated variable information and compares this information on an ongoing basis to detect system instability, and when detected, effects modification of the horizon window to remove the instability.
Claim 4
Dependent Claim
42 words
A controller according to Claim 3 characterised in that the determination of instability will provide for one of three alternative actions on the part of the tuner (23): (a) change the horizon window, (b) change the identified model, (c) initiate a retune.
Claim 5
Dependent Claim
33 words
A controller according to any preceding Claim characterised in that the horizon window established by the tuner (23) is based on the inflection point as well as the line-out of the plant output.
Claim 6
Dependent Claim
63 words
A controller according to any of Claims 2 to 5 characterised in that said optomizer calculator means (28) establishes an optimal cost value set for the free manipulated variables at the current time increment by iteratively finding the costs for a range of values of the free manipulated variables and selecting the lowest cost subset using the feedforward capability of the control law.
Claim 7
Dependent Claim
53 words
A controller according to any preceding Claim characterised in that the user input includes specification of the horizon window by specifying one or both of the lengths of m and l, the set point, the manipulated variable values in the manual control mode, the control mode (automatic, manual, tune), and the cost function.
Claim 8
Dependent Claim
35 words
A controller according to Claim 6 or 7 characterised in that the iterative cost finding function is repeated for each increment within the horizon window and the optimization process is repeated at each control step.
Claim 9
Independent Claim
203 words
A method of controlling the manipulated variable inputs to a plant to achieve a desired controlled variable output trajectory which is sensitive to the outputs from said plant wherein said method includes receiving user input and providing output signals to effect control moves to establish a model identification based on the manipulated variable inputs and the controlled variable outputs from the plant, said method characterised by: establishing a control sample rate and the first m increments of a horizon window which has a total of m+l increments and predicting the nominal control variable output trajectory that would occur without changes to the manipulated variables, said predicting step incorporating deriving its model from the identified model, and specifying the changes required of the manipulated variable outputs to satisfy the following criteria: a) the errors between the controlled variables and their respective setpoints become zero after m control moves b) the errors between the controlled variables and their respective setpoints are zero for l additional control moves c) the change in the manipulated variables during the last n control moves of the m+l horizon take on their prescribed beta values said specified manipulated variable changes being used to determine the output signals for the actuators.
Claim 10
Dependent Claim
157 words
A process for regulating a system with a controller which provides inputs to a plant and receives outputs from the plant indicating changes in the plant, the process characterised by the steps of: a) establishing a horizon window comprised of sampling increments of time such that the sampling interval will be long enough to provide useful control move change periods and short enough to substantially reduce the appearance of unwanted oscillations of the controlled variable trajectory, b) predicting the nominal controlled variable output trajectory, c) predicting the controlled output trajectory based on the control moves required to reach a user-defined setpoint trajectory at a given time of m increments within the horizon window, d) constraining the controlled output trajectory to remain at the user defined output state for l increments beyond said m increments, and constraining the control moves to a user specified beta for the last n increments of the l part of the horizon window.
Claim 11
Dependent Claim
74 words
A method according to Claim 9 or 10, characterised by providing manipulated variable sequences that results in optimal cost performance without compromising servo-regulatory performance including the steps of: predicting the effect on the plant as would be measured by the outputs of any hypothetical change made in any manipulated variable, determining the optimal set of manipulated variable changes during the horizon window based on the predicted effects of the changes over the horizon window.
Claim 12
Dependent Claim
44 words
A method according to Claim 9, 10 or 11 characterised by receiving plant output information and manipulated variable information and comparing this information on an ongoing basis to detect system instability, and when detected effecting modification of the horizon window to remove the instability.
Claim 13
Dependent Claim
33 words
A method according to Claim 12, characterised by the determination of instability providing for one of three alternative actions: a) change the horizon window, b) change the identified model, c) initiate a retune.
Claim 14
Independent Claim
33 words
A method according to any of Claims 9 to 13 characterised in that the horizon window as established is based on the inflection point as well as the line-out of the plant output.
Claim 15
Independent Claim
57 words
A method according to any of Claims 11 to 14 characterised by establishing an optimal cost value set for the free manipulated variables at the current time increment by iteratively finding the costs for a range of values of the free manipulated variables and selecting the lowest cost subset using the feedforward capability of the control law.
Claim 16
Independent Claim
56 words
A method according to any of Claims 9 to 15 characterised in that the user input includes specification of the horizon window by specifying one or both of the lengths of m and l, the set point, the manipulated variable values in the manual control mode, the control mode (automatic, manual, tune), and the cost function.
Claim 17
Independent Claim
37 words
A method according to any of Claims 14 to 16 characterised in that the iterative cost finding function is repeated for each increment within the horizon window and the optimization process is repeated at each control step.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
Maintenance schedule is calculated for granted US utility patents.