Exponential functional relationship generator method and system for implementation in digital logic

• US 5,935,200 A
• Filed: 11/21/1997
• Issued: 08/10/1999
• Est. Priority Date: 11/21/1997
• Status: Expired due to Term

• Current Assignee: Unisys Corporation
• Original Assignee: Unisys Corporation
• Inventors: Whittaker, Bruce Ernest
• Primary Examiner(s): Malzahn, David H.
• Application Number:
  US08/975,273
• Time in Patent Office: 627 Days
• Field of Search: 364/753, 364/722, 364/735, 708/606, 708/277, 708/446
• US Class Current: 708/606
• CPC Class Codes: G06F 7/556 Logarithmic or exponential functions

Abstract

A system and method for developing a digital control signal Y for setting a target module (D) according to a digital setpoint signal A, a digital feedback signal C, a difference digital signal X=A-C in an exponential relationship, such that Y=2^X+1 -1. An N bit digital signal X is translated exponentially via a simple, non-complex programmable array logic unit to an expanded N+q digital bit signal providing an exponentially expanded response for the control signal Y to reset the target module D to an optimally desired setting.

Claims

1. A method for exponentially expanding the digital signal value of a first valued input digital signal (X) into a second-valued digital output signal (Y) for controlling the setting of a target digital module (D) whereby Y is a dependent variable exponentially related to a digital signal X where X represents the difference between a set-point signal A and a feedback signal C, said method comprising the steps of:

(a) generating a difference signal X on bus lines of n digital bits where X is the value of said set-point signal (A) reduced by said feedback signal (C) from said target digital module (D);

(b) utilizing said input digital signal (X) plus the integer 1 as an exponent of the base "2" in a gating unit as input to develop a digital output control signal Y on output bus lines of n+q bits for exponentially expansive control of said target digital module, (D), by implementing the sequence of Y=2^X+1 -1.

2. The method of claim 1 which includes the step of:

(c) converting said digital output signal Y to an exponentially expansive voltage value for control of said target digital module back to a set-point which will make X=0.

3. A system for digitally generating a control signal for a target module utilizing an exponential expansion logic circuit for increasing an N bit digital input signal to an N+q bit digital output signal, said system comprising:

(a) means to develop a digital difference signal X an input bus of N bit lines where X represents the digital difference value between a set-point signal A reduced by a feedback signal C from said target module;

(b) means to utilize the binary base "2" raised to the X+1 power for developing a value which is reduced by "1" to generate a resultant digital output signal Y of N+q bits where q represents a digital offset value corresponding to the exponential digital value of X.

4. The system of claim 3 where said means to develop a digital difference signal X includes:

(a1) means to generate said digital set-point signal A by an operator through a digital signal generator;

(a2) means to sense the deviation of said target module from a desired set-point generated by said signal A to provide said digital difference signal X.

5. The system of claim 3 where said means to utilize the base 2 raised to the X+1 power includes:

(b1) programmable array logic (PAL) means providing a combination of AND-OR logic gates for transforming said N bit input X signal to an N+q bit output signal Y and for solving the equation Y=2^X+1 -1.

6. The system of claim 5 wherein said programmable array logic means includes:

(b1a) means for utilizing said N bit digital input signal X as input to develop said N+q bit digital output signal Y for control of said target module at a desired setting.

7. A method for developing an output digital control signal Y for controlling a target device (D) where signal Y is an exponentially expanded value of an input digital signal (X) which represents the difference between a digital set-point signal (A) and a digital feedback signal (C) comprising the steps of:

(a) generating a digital difference signal X as the digital difference between a set-point signal (A) and a feedback signal (C), said signal X designated as a digital input signal to a logic gating unit;

(b) feeding said logic gating unit with "mi" digital input lines of said digital input signal X;

(c) retrieving from said logic gating unit, which executes the equation of Y=2^X+1 -1, an output control signal Y of "mo" digital lines where "mo" is larger in numerical value than "mi".

8. The method of claim 7 which further includes the step of:

(d) transmitting said output control signal Y to a target device (D).