Multivariable nonlinear process controller

An apparatus for controlling a process having process inputs and process outputs comprising at least one controlled variable, the process being responsive to at least one manipulated variable for changing the process in relation to the controlled variable, said apparatus comprising:

• a) measuring means for measuring values of at least one of said process outputs and generating at least one process output signal representative thereof;
• b) setpoint means for receiving at least one setpoint which represents a target value of the controlled variable;
• c) control means, coupled to said measuring means and the process, for generating a selected value of the manipulated variable and at least one optimum prediction time as a function of the setpoint and the process output signal, said control means utilizing a nonlinear function generator previously trained to determine a selected value of the manipulated variable and the optimum prediction time, the optimum prediction time representing the effective response time of the process to a change in the setpoint, and the selected value of the manipulated variable representing a change in the process needed to produce a value of the controlled variable that approaches the setpoint as advanced by the optimum prediction time;
• d) an integral control means for providing integral control action in response to the process output signal, the setpoint, and the optimum prediction time, thereby calculating an inner setpoint in order to compensate for process changes, the optimum prediction time being used in generating an integral time constant, said integral control means producing the inner setpoint for use by the control means;
• and
• e) actuator means, coupled to said control means and the process, for applying the manipulated variable to the process.

An apparatus for controlling a process having process inputs and process outputs comprising at least one controlled variable and at least one inferential variable, the process responsive to at least one manipulated variable for changing the process in relation to the controlled variable, said apparatus comprising:

• a) a first measuring means for measuring values of a measured process output generating at least one controlled variable representative thereof;
• b) a second measuring means for measuring a process output thereby producing an approximate indication of the controlled variable and generating at least one inferential variable representative thereof;
• c) setpoint means for receiving at least one setpoint which represents a target value of the controlled variable;
• d) control means, coupled to said measuring means and the process, for generating a selected value of the manipulated variable and at least one optimum prediction time as a function of the setpoint and the inferential variable, said control means utilizing a nonlinear function generator previously trained to determine the selected value of the manipulated variable and the optimum prediction time, the optimum prediction time representing the effective response time of the process to a change in the setpoint, and the selected value of the manipulated variable representing a change in the process needed to produce the controlled variable that approaches the setpoint as advanced by the optimum prediction time;
• e) an integral control means for providing integral control action in response to the controlled variable, the setpoint, and the optimum prediction time, thereby computing an inner setpoint in order to compensate for process changes, the optimum prediction time being used for generating the integral time constant, said integral control means producing the inner setpoint for use by the control means;
• and
• f) an actuator means coupled to said control means and the process, for applying the manipulated variable to the process.

A multivariable nonlinear controller for controlling a process having process outputs comprising of at least one controlled variable, and an actuator affecting the process, the controller comprising:

• a) means for receiving a signal representative of at least one of the process outputs;
• b) means for receiving at least one setpoint indicating a target value of the controlled variable;
• c) control means, in communication with the process output signal and the setpoint, said control means, utilizing a nonlinear function generator to produce at least one selected value of the manipulated variable to affect the process, said control means performing the operations of:
• i) performing an integral control action using the process output signal, the setpoint, and an integral time constant, and generating at least one adjusted setpoint representative thereof;
• ii) operating the nonlinear function generator as a function of the process output signal and the adjusted setpoint, and producing an optimum prediction time representing a response time of the controlled variable to the adjusted setpoint, the optimum prediction time used to compute the integral time constant for the integral control action, the nonlinear function generator producing the selected value of the manipulated variable for affecting the controlled variable as advanced by the optimum prediction time;
• and
• iii) transmitting the selected value of the manipulated variable to the actuator for affecting the process.

A multivariable nonlinear controller for controlling a process having a process output comprising controlled and inferential variables, and an actuator affecting the process, the controller comprising:

• a) means for receiving at least one process output signal;
• b) means for generating at least one inferential variable representing approximate indications of the controlled variable;
• c) means for receiving at least one setpoint indicating a target value of the controlled variable;
• d) control means, in communication with the process output signal and the setpoint, said control means, utilizing a nonlinear function generator to produce at least one selected value of the manipulated variable to affect the process, said control means performing the operations of:
• i) performing an integral control action using the process output signal, the setpoint, and an integral time constant, and generating at least one adjusted setpoint representative thereof;
• ii) operating the nonlinear function generator in response to the inferential variable and the adjusted setpoint, and producing an optimum prediction time representing a response time of the controlled variable to the adjusted setpoint, the optimum prediction time used to generate the integral time constant for the integral control action, the nonlinear function generator producing the selected value of the manipulated variable for affecting the controlled variable to approach the setpoint as advanced by the optimum prediction time;
• and
• iii) transmitting the manipulated variable to the actuator for affecting the process.

A method for controlling a process having process inputs, process outputs comprising of at least one controlled variable, and an actuator affecting the process, the method utilizing a nonlinear function generator for computing at least one manipulated variable for use by the actuator to affect the controlled variable, the method comprising the steps of:

• a) measuring the process output generating at least one process output signal representative thereof;
• b) receiving at least one setpoint representing the target value of the controlled variable;
• c) operating the nonlinear function generator as a function of the process output signal and the setpoint to generate a selected value of the manipulated variable, the nonlinear function generator previously trained to generate the selected value of the manipulated variable based on an optimum prediction time, the optimum prediction time representing a response time of the controlled variable to the setpoint, and the selected value of the manipulated variable representing a change made to the process in order to affect the controlled variable to approach the setpoint as advanced by the optimum prediction time;
• and
• d) transmitting the manipulated variable to the actuator for applying the manipulated variable to the process.

A system for controlling a process, the process having process inputs, process outputs comprising of a plurality of controlled variables, and an actuator affecting the process, the system comprising:

• a) first control means for generating a plurality of selected values of the manipulated variables for use by the actuator for affecting the process, said first control means performing the steps of:
• i) measuring load disturbances of the process and generating a plurality of measured load variables representative thereof and generating the derivative, with respect to time, of the measured load disturbances, thereby producing a plurality of derivative measured load variables representative thereof;
• ii) measuring a plurality of process outputs generating a plurality of process output signals representative thereof and generating the derivative of the process output signal producing a plurality of derivative process output signals representative thereof;
• iii) receiving a plurality of adjusted setpoints representing values of the controlled variables for use by the first control means in determining the selected values of the manipulated variables;
• iv) producing the selected values of the manipulated variables and a plurality of optimum prediction times as a function of the adjusted setpoints, the measured load variables, the derivative measured load variables, the inferential variables, and the derivative inferential variables, the optimum prediction time representing a response time of the controlled variable to the adjusted setpoint, and the selected values of the manipulated variable representing changes made to the process in order to affect the controlled variables to approach the adjusted setpoints as advanced by the optimum prediction time;
• v) transmitting the selected values of the manipulated variable to the actuator for application to the process;
• b) second control means for generating the adjusted setpoint by performing the steps of:
• i) receiving a desired setpoint representing a target value of the process;
• ii) measuring the process thereby generating a controlled variable representative thereof;
• iii) determining whether the manipulated variable has been limited and generating a logic signal representative thereof;
• and
• iv) calculating the adjusted setpoint by performing an integral control action as a function of the desired setpoint, the controlled variable, the logic signal, and the optimum prediction time produced from said first control means, said calculation step producing the adjusted setpoint for use by the first control means in generating the manipulated variables which will affect the process.