Adaptive gain controller

• US 4,218,733 A
• Filed: 11/13/1978
• Issued: 08/19/1980
• Est. Priority Date: 11/13/1978
• Status: Expired due to Term

• Current Assignee: ABB Instrumentation SpA (ABB Limited)
• Original Assignee: Sybron Corporation (Envista Holdings Corporation)
• Inventors: Maselli, Stephen A.
• Primary Examiner(s): Ruggiero, Joseph F.
• Application Number:
  US05/959,498
• Time in Patent Office: 645 Days
• Field of Search: 364/105, 364/106, 364/118, 364/120, 318/561, 318/619, 318/620, 318/609, 318/610
• US Class Current: 700/37
• CPC Class Codes: G05B 13/0205 not using a model or a simulator of the controlled system

Abstract

A controller for process control has an adaptive gain. The controller is used as part of a closed feedback loop, and will, in response to different variables, maintain a constant loop gain regardless of non-linearities in the system.

Signals representing the variables are transformed into corresponding active gain factors. The active gain of the controller is computed as a function of the product of the active gain factors and then translated to an output signal. One or more active gain factor is defined as having a first gain factor, at least one breakpoint, and a second gain factor. If two breakpoints are used, a base gain is interposed. Furthermore, one or more variables may have a step function as an active gain factor.

Claims

1. A controller for closed loop control of a process, said controller having the ability to change its active gain to compensate for process non-linearity so as to maintain a substantially constant closed loop gain, and being comprised of:

a plurality of inputs for receiving signals representing variables;

computing means for transforming said signals into corresponding active gain factors and for computing the active gain of the controller as a function of the product fo the active gain factors; and

means for translating the calculated active gain to an output signal;

wherein at least one of said variables has a corresponding active gain factor defined by a first corresponding gain factor, a breakpoint, and a second corresponding gain factor.

2. The controller of claim 1 wherein said corresponding active gain factor is further defined by said first corresponding gain factor, said breakpoint, a second breakpoint, a corresponding base gain interposed between said breakpoints, and said second corresponding gain factor.

3. The controller of claim 1 wherein each of a first set of said variables has a corresponding active gain factor defined by a first corresponding gain factor, a breakpoint and a second corresponding gain factor and each of a second set of variables has a corresponding active gain factor characterized as a step function.

4. The controller of claim 3 wherein the first set of variables represent process, deviation and remote input and the second set of variables represent output and external contact.

5. The controller of claim 1 wherein each of a first set of variables has a corresponding active gain factor defined by a first corresponding gain factor, a first breakpoint, a second breakpoint, a corresponding base gain interposed between said breakpoints, and a second correspondinng gain factor and each of a second set of variables has a corresponding active gain factor characterized as a step function.

6. The controller of claim 5 wherein the first set of variables represent process, deviation, and remote input and the second set of variables represent controller output and external contact.

7. The controller of claims 4 or 6 wherein one variable in the first set is used for both process and remote output.