Parameterized neurocontrollers

• US 5,486,996 A
• Filed: 01/22/1993
• Issued: 01/23/1996
• Est. Priority Date: 01/22/1993
• Status: Expired due to Term

• Current Assignee: Honeywell Incorporated (Honeywell International Inc.)
• Original Assignee: Honeywell Incorporated (Honeywell International Inc.)
• Inventors: Graber, Wendy K. F., Konar, Ahmet F., Samad, Tariq
• Primary Examiner(s): Gordon, Paul P.
• Application Number:
  US08/008,963
• Time in Patent Office: 1,096 Days
• Field of Search: 364/148, 364/152, 364/162, 364/157, 364/158, 364/187, 395/21, 395/23, 395/22
• US Class Current: 700/32
• CPC Class Codes: G05B 13/027 using neural networks only

Abstract

A controller based on a neural network whose output is responsive to input signals that represent user or designer defined control system parameters which may include process parameters, control parameters and/or disturbance parameters. The neural network can be "trained" to mimic an existing controller which may or not receive inputs of control system parameters. The trained neural network controller may have advantages of faster execution and reduced code size. The neural network can also be trained to result in a nonlinear controller that is more powerful than an existing controller.

Claims

1. A controller of a process which accepts modification of its behavior through input signals representative of parameters that are members of a set of parameters including:

control parameters p_c, process parameters p_p, and disturbance parameters p_d (which may collectively be called P) wherein said controller comprises a neural network;

wherein the neural network is trained to mimic an existing controller which receives inputs from the set of all P inputs or any subset thereof (except only the subset including only P, I and D inputs), and x_p, y, y_r, u and all algebraic, differential and integral operators of these x_p, y, y_r and u inputs, and has an output in a closed loop use, said training occurring by;

collecting said P parameters, said x_p, y_r, y, u and any other of said inputs as data, and

using said collected data as training data in a learning program which modifies the neural network in a training phase at least until an output from said neural network is similar or identical to the acceptable output generated by said existing controller;

wherein;

x_p is dynamic state variables of the process,

y is a process output signal,

y_r is a reference input signal, and

u is a control adjustment signal and,

coupling said modified neural network to a second process similar to a first process previously controlled by the existing controller; and

applying said neural network to the second process using inputs that the existing controller would have used to control the first process so that the neural network controls the second process.

2. A controller as set forth in claim 1 wherein said controller comprises an input controller processor and a plurality of other controllers, at least one of which other controllers is a neural network.

3. A controller as set forth in claim 2, wherein said input controller processor passes data to inputs of the plurality of other controllers and wherein at least one of said plurality of other controllers further comprises an output controller processor that reviews outputs of said input controller processor and said plurality of other controllers and determines which of those outputs is used as input to the process.

4. A controller as set forth in claim 1 wherein the neural network is trained to extremize criteria using any training method from the set of training methods:

Stochastic, non-gradient based, nonlinear;

genetic;

steepest descent; and

second order methods.

5. A controller as set forth in claim 1 wherein training is done off-line over a variety of process models.

6. A controller as set forth in claim 1, wherein the neural network is trained to mimic an existing controller which receives inputs from the set of all P inputs or any subset thereof (except only the subset including P,I and D inputs), and x_p, y, y_r, u and all algebraic, differential and integral operators of these x_p, y, y_r and u inputs, with an output in a closed loop use, said training occurring by:

placing said neural network into the closed control loop so as to receive said P parameters, said x_p, y_r, y, u and any other of said inputs and also input from a learning program which modifies the network in a training phase at least until the u output from said neural network is similar or identical to the output generated by said existing controller,

allowing said existing controller to run in said closed-loop use until said training phase is accomplished; and

,

placing the trained neural network in the closed loop so as to run the process in said closed-loop use.

7. A controller as set forth in claim 6 wherein said neural network, after said training phase, is employed to run said closed-loop use.

8. A controller of a process which accepts modification of its behavior through input signals representative of parameters that are members of a set of parameters including:

control parameters p_c, process parameters p_p, and disturbance parameters p_d (which may collectively be called P) wherein said controller comprises a neural network;

wherein said inputs received by said controller are from the set of inputs including all P inputs or any subset thereof (except only P,I,D inputs), and x_p, y, y_r, u and all algebraic, differential and integral operators of these x_p, y, y_r and u inputs;

wherein training is done off-line over a variety of process models, and further comprising;

an input controller processor means for passing data to other controllers and wherein said input controller processor means further comprises an output controller processor that reviews the outputs of other controllers and determines which of those is used as input to the process, wherein;

x_p is dynamic state variables of the process,

y is a process output signal,

y_r is a reference input signal, and

u is a control adjustment signal; and

wherein the output controller processor provides an output signal that is used as input to the process as determined by said output controller processor.

9. A controller of a process which accepts modification of its behavior through input signals representative of parameters that are members of a set of parameters including:

control parameters p_c, process parameters p_p, and disturbance parameters p_d (which may collectively be called P) wherein said controller comprises a neural network;

wherein said inputs received by said controller are from the set of inputs including all P inputs or any subset thereof (except only P,I,D inputs), and x_p, y, y_r, u and all algebraic, differential and integral operators of these x_p, y, y_r and u inputs;

wherein said controller comprises an input controller processor and a plurality of other controllers, at least one of which other controllers is a neural network; and

wherein;

x_p is dynamic state variables of the process,

y is a process output signal,

y_r is a reference input signal, and

u is a control adjustment signal; and

wherein said controller provides a control signal to at least one actuator associated with the process so that a detectable physical change occurs in the characteristics of the process.