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EP-4063975-B1 - RST SMITH PREDICTOR

EP4063975B1EP 4063975 B1EP4063975 B1EP 4063975B1EP-4063975-B1

Inventors

  • FALCONI, FRANCO
  • CAPITANEANU, STEFAN
  • GUILLARD, Hervé
  • RAÏSSI, Tarek

Dates

Publication Date
20260506
Application Date
20220222

Claims (14)

  1. A control system (100) for controlling a device or system, comprising: memory; and at least one processor configured to: receive (1310) a setpoint signal as input; and perform (1320) closed loop control of the device or system by outputting a control signal according to the setpoint signal and a response model of the device or system using a predictive control algorithm, the predictive control algorithm being a Smith predictor and configured to implement control according to a polynomial representation for regulation, sensitivity and tracking and further implement non-linearity or time delay compensation using the response model, the closed loop control being tunable using an adjustable single parameter for accelerating or decelerating the closed loop control relative to an open loop control scenario, wherein the polynomial representation comprises at least transfer functions R, S and T for regulation, sensitivity and tracking, respectively, a coefficient of each of the transfer functions R, S and T being a function of the adjustable single parameter, and wherein the response model includes a linear part and a non-linear part, and the predictive control algorithm employs the response model to remove non-linearity, thereby compensating for time delay and enabling linear control through an RST control strategy.
  2. The control system (100) of any one of the preceding claims, wherein the closed loop control includes a feedback loop to an output of a command law to make an estimation of an input disturbance.
  3. The control system (100) of any one of the preceding claims, wherein the device or system comprises equipment to be controlled in an industrial process or system.
  4. The control system (100) of any one of the preceding claims, wherein the time delay comprises a dead time.
  5. The control system (100) of any one of the preceding claims, further comprising: one or more sensors for sensing operating characteristic(s) of the device or system, which is feedback for closed loop control.
  6. The control system (100) of any one of the preceding claims, wherein the memory and at least one processor are part of a controller for an industrial process or system.
  7. A computer-implemented method (1300) of controlling a device or system, comprising: receiving (1310) a setpoint signal as input; and performing (1320) closed loop control of the device or system by outputting a control signal according to the setpoint signal and a response model of the device or system using a predictive control algorithm, the predictive control algorithm being a Smith predictor and configured to implement control according to a polynomial representation for regulation, sensitivity and tracking and further implement non-linearity or time delay compensation using the response model, the closed loop control being tunable using an adjustable single parameter for accelerating or decelerating the closed loop control relative to an open loop control scenario, wherein the polynomial representation comprises at least transfer functions R, S and T for regulation, sensitivity and tracking, respectively, a coefficient of each of the transfer functions R, S and T being a function of the adjustable single parameter, and wherein the response model includes a linear part and a non-linear part, and the predictive control algorithm employs the response model to remove non-linearity, thereby compensating for time delay and enabling linear control through an RST control strategy.
  8. The computer-implemented method (1300) of claim 7, wherein the closed loop control includes a feedback loop to an output of a command law to make an estimation of an input disturbance.
  9. The computer-implemented method (1300) of any one of claims 7 - 8, wherein the device or system comprises equipment to be controlled in an industrial process or system.
  10. The computer-implemented method (1300) of any one of claims 7 - 9, wherein the time delay comprises a dead time.
  11. The computer-implemented method (1300) of any one of claims 7 - 10, further comprising: sensing operating characteristic(s) of the device or system using one or more sensors, the sensed operating characteristic(s) being feedback for closed loop control.
  12. The computer-implemented method (1300) of any one of claims 7 - 11 , further comprising: analyzing operation(s) of the device or system to determine if the closed loop control needs to be tuned; and adaptively tuning the closed loop control using the adjustable single parameter if the closed loop control needs to be tuned.
  13. The computer-implemented method (1300) of any one of claims 7 - 12, wherein the operations of receiving and performing are implemented by a controller for an industrial process or system.
  14. A tangible computer medium storing computer executable code, which when executed by one or more processors, is configured to implement a method of controlling a device or system, the method comprising: receiving a setpoint signal as input; and performing closed loop control of the device or system by outputting a control signal according to the setpoint signal and a response model of the device or system using a predictive control algorithm, the predictive control algorithm being a Smith predictor and configured to implement control according to a polynomial representation for regulation, sensitivity and tracking and further implement non-linearity or time delay compensation using the response model, the closed loop control being tunable using an adjustable single parameter for accelerating or decelerating the closed loop control relative to an open loop control scenario, wherein the polynomial representation comprises at least transfer functions R, S and T for regulation, sensitivity and tracking, respectively, a coefficient of each of the transfer functions R, S and T being a function of the adjustable single parameter, and wherein the response model includes a linear part and a non-linear part, and the predictive control algorithm employs the response model to remove non-linearity, thereby compensating for time delay and enabling linear control through an RST control strategy.

Description

FIELD The present disclosure is directed to a control system for controlling a device or system, a computer-implemented method of controlling a device or system, and a tangible computer medium storing computer executable code. BACKGROUND Process control can refer to a methodology for controlling the operational parameters of a process by monitoring one or more of its characteristics over time. It is used to ensure that the quality and the efficiency of a process do not vary substantially during a single run or over the course of several runs. Process control can be employed in the manufacturing sector as well as service and other industries. LANDAU I D: "Robust digital control of systems with time delay (the Smith predictor revisited)", PROCEEDINGS OF THE 33RD IEEE CONFERENCE ON DECISION AND CONTROL, 1994., discloses a predictive control system using a Smith-predictor combined with an RST controller. SUMMARY The present disclosure provides a control system for controlling a device or system according to claim 1, a computer-implemented method of controlling a device or system according to claim 7 and a tangible computer medium storing computer executable code according to claim 14. Embodiments are given in the subclaims, the description and the drawings. The control method and system can be implemented, for example, through a controller(s) for an industrial process or system. According to the invention, the response model includes a linear part and a non-linear part (e.g., pure delay or feedback delay). The predictive control algorithm employs the response model to remove non-linearity (e.g., separate the linear part from the non-linear part), thereby compensating for time delay and enabling linear control through an RST control strategy (e.g., the linear part is controlled by the RST control strategy). The time delay can be a dead time. In accordance with an embodiment, the closed loop control can include a feedback loop to an output of a command law to make an estimation of an input disturbance. In accordance with another embodiment, the device or system comprises equipment to be controlled in an industrial process or system. In yet a further embodiment, the control method and system can further involve sensing operating characteristic(s) of the device or system using one or more sensors. The sensed operating characteristic(s) can be feedback for closed loop control. Furthermore, the control method and system also can involve analyzing operation(s) of the device or system to determine if the closed loop control needs to be tuned; and adaptively tuning the closed loop control using the adjustable single parameter (e.g., changing a value of the parameter) if the closed loop control needs to be tuned. The closed loop control can be adaptively tuned according to analysis of the operations of the device or system or sensed, measured or derived operating characteristic(s) of the device or system. DESCRIPTION OF THE FIGURES The description of the various example embodiments is explained in conjunction with the appended drawings. Fig. 1 is a high-level block diagram of an example control system using a predictive control algorithm, in accordance with an embodiment of the present disclosure.Fig. 2 is block diagram of a general structure of a Smith predictor.Fig. 3 is a block diagram of an RST Smith predictor or controller incorporating an additional feedback to the output of the command law to make an estimation of the input disturbance, which can be implemented in the control system of Fig. 1, in accordance with an embodiment of the present disclosureFig. 4 is an open loop block diagram related to the control architecture of Fig. 3.Fig. 5 is a graph showing simulation results of system output for the different control methods, in accordance with an embodiment.Fig. 6 is a graph showing simulation results of controller output for the different control methods, in accordance with an embodiment.Fig. 7 is a graph showing simulation results of system output for the different control methods, in accordance with an embodiment.Fig. 8 is a graph showing simulation results of controller output for the different control methods, in accordance with an embodiment.Fig. 9 is a graph showing simulation results of system output for the different control methods, in accordance with an embodiment.Fig. 10 is a graph showing simulation results of controller output for the different control methods, in accordance with an embodiment.Fig. 11 illustrates a block diagram of an RST Smith predictor or controller incorporating an additional feedback to the output of the command law to make an estimation of the input disturbance, which can be implemented in the control system of Fig. 1, in accordance with a further embodiment of the present disclosure.Fig. 12 illustrates an example method of configuring a control system, such as in Fig. 1, to implement an RST Smith predictor or controller to control operation of a device or system (e.g., a plan