Method for computer-aided design of a product or process

• US 6,289,255 B1
• Filed: 11/24/1998
• Issued: 09/11/2001
• Est. Priority Date: 11/25/1997
• Status: Expired due to Term

• Current Assignee: Tokyo Electron Limited
• Original Assignee: Voyan Technology Incorporated (Plantronics, Inc.)
• Inventors: Shah, Sunil C., Pandey, Pradeep
• Primary Examiner(s): Gordon, Paul P.
• Assistant Examiner(s): Garland, Steven R.
• Application Number:
  US09/199,708
• Time in Patent Office: 1,022 Days
• Field of Search: 700/33, 700/53, 700/36, 700/97, 700/98, 700/274, 700/266, 700/121, 700/104, 700/83, 700/105, 700/165, 700/182, 705/8, 703/1, 703/2, 716/1, 716/2, 716/4, 716/9, 716/10, 706/903, 706/904, 706/919, 706/920, 706/921
• US Class Current: 700/97
• CPC Class Codes: G05B 17/02 electric
• CPC Class Codes: G06F 30/00 Computer-aided design [CAD]

Abstract

A method for computer-aided design. The method includes the steps of representing a computer-aided design activity as a design cycle and defining a goal of the design activity. The method also includes the steps of defining alternate design steps toward achieving the goal. According to one embodiment, the design activity is represented as a graph containing the alternate design steps. According to this embodiment, a cost metric is assigned for each of the alternate design steps that includes elements representing relative costs of taking each of a plurality of paths in the graph. Element values and bounds on the cost metric are the determined by searching the graph to project costs incurred upon execution of each of the alternate design steps to achieve the goal. The cost of achieving the goal is then optimized by selecting one of the alternate design steps associated with a smallest cost metric.

Claims

1. A method for computer-aided design comprising the steps of:

representing a computer-aided design activity as a design cycle;

defining a goal of the design activity;

defining a first design step toward achieving the goal;

defining an alternate design step toward achieving the goal;

assigning a cost metric for each of the first design step and the alternate design step;

estimating relative costs and bounds on the cost metric; and

optimizing a cost of achieving the goal.

2. The method of claim 1, further comprising the step of:

representing the design activity as a graph containing the first design step and the alternate design step.

3. The method of claim 2, wherein the step of estimating element values and bounds on the cost metric is performed by searching the graph to project costs incurred upon execution of the first design step and the alternate design step to achieve the goal.

4. The method of claim 2, wherein the graph is a state space graph comprising a plurality of design states, each including a plurality of alternative design substeps and outcomes of the plurality of alternative design substeps.

5. The method of claim 1, wherein the step of assigning a cost metric includes elements representing relative costs of taking each of a plurality of paths in the graph.

6. The method of claim 1, wherein the step of optimizing a cost of achieving the goal is performed by selecting one of the first design step and the alternate design step associated with a smallest cost metric.

7. The method of claim 1, further comprising the steps of:

executing the design cycle, including,

receiving an actual cost metric element value during execution;

replacing an estimated value of the cost metric element with the actual value;

reestimating bounds on the cost metric using the actual value; and

reoptimizing the cost of achieving the goal.

8. The method of claim 7, further comprising the steps of:

receiving an indication of whether accuracy or speed is a more important design criterion; and

using the indication in the step of reoptimizing.

9. The method of claim 1, wherein the design cycle requires a plurality of iterations, and wherein the step of optimizing includes performing calculations using an incremental algorithm that uses results of calculations related to one iteration of the plurality of iterations in calculations related to subsequent iterations of the plurality of iterations.

10. The method of claim 1, further comprising the steps of:

receiving an indication of whether accuracy or speed is a more important design criterion; and

using the indication in the step of optimizing.

11. The method of claim 1, wherein the cost metric comprises an interaction complexity that is a quantification of an amount of information to be processed by the user for a transaction between the user and a user interface.

12. The method of claim 1, wherein the cost metric comprises a computational complexity that is an indication of a number of computational operations to be performed in a computational task.

13. The method of claim 1, wherein the cost metric comprises a computational response time that indicates a time for a machine to complete a computation.

14. The method of claim 1, wherein the cost metric comprises a number of required user decisions in an interaction between a user and a user interface.

15. The method of claim 1, wherein the cost metric comprises an equipment test time.

16. The method of claim 1, wherein the cost metric comprises an estimate of numerical reliability that is an indication of numerical accuracy of results and sensitivity to numerical input errors.

17. The method of claim 1, further comprising the step of independently computing an error computation.

18. A method for designing a signal processing system that is represented as a design cycle, comprising the steps of:

using the design cycle representation to create a plurality of alternate process steps toward achieving a predefined goal of the signal processing system;

assigning cost metrics to each of the alternate process steps;

estimating a range of values for each of the assigned cost metrics; and

optimizing a cost of achieving the predefined goal.

19. The method of claim 18, wherein the plurality of alternate process steps are contained in a graph.

20. The method of claim 19, wherein the step of assigning cost metrics is performed using a plurality of paths between the alternate process steps on the graph.

21. The method of claim 20, wherein the step of estimating a range of values is performed based upon projected execution of each of the plurality of paths.

22. The method of claim 20, wherein the step of optimizing the cost of achieving the predefined goal is performed by selecting one of the plurality of paths associated with a smallest cost metric of the assigned cost metrics.

23. The method of claim 19, wherein the graph is a state space graph and wherein at least one of the plurality of alternate process steps comprises a plurality of alternate methods by which the process step is accomplished, further including the step of choosing a method of the alternate methods.

24. The method of claim 23, further comprising the steps of:

performing at least one iteration of the design cycle using the optimized cost;

during an iteration of the design cycle, receiving at least one actual value for at least one of the assigned cost metrics;

replacing the estimated range of values for the assigned cost metric with the actual value;

reestimating a range of values for remaining assigned cost metrics; and

reoptimizing the cost of achieving the predefined goal.

25. The method of claim 24, further comprising the steps of:

receiving an indication of whether accuracy or speed is a more important design criterion; and

using the indication in the step of reoptimizing.

26. The method of claim 18, further comprising the steps of:

receiving an indication of whether accuracy or speed is a more important design criterion; and

using the indication in the step of optimizing.

27. The method of claim 18, wherein the cost metrics comprise an interaction complexity that is a quantification of an amount of information to be processed by the user for a transaction between the user and a user interface.

28. The method of claim 18, where in the cost metrics comprise a computational complexity that is an indication of a number of computational operations to be performed in a computational task.

29. The method of claim 18, where in the cost metrics comprise a computational response time that indicates a time for a machine to complete a computation.

30. The method of claim 18, wherein the cost metrics comprise a number of required user decisions in an interaction between a user and a user interface.

31. The method of claim 18, wherein the cost metrics comprise an equipment test time.

32. The method of claim 18, wherein a cost metric comprises an estimate of numerical reliability that is an indication of numerical accuracy of results and sensitivity to numerical input errors.

33. The method of claim 18, further comprising the step of independently computing an error computation.

34. The method of claim 18, wherein the process is the thermally activated process of silicon oxide growth carried out in an oxidation furnace, and wherein the signal processing system controls the oxidation furnace.

35. The method of claim 34, further comprising the steps of:

during execution of the design cycle, receiving measured values for physical properties of the process; and

converting the measured values to visual representations for display on a computer display including graphical representations and pictorial representations.

36. The method of claim 35, further comprising the steps of:

displaying representations of design steps in the design cycle on the computer display;

receiving an indication from a user of a design step of the design steps to be executed.

37. The method of claim 36, further comprising the step of displaying a representation of the cost metrics on the computer display.

38. A computer readable medium having stored thereon instructions which when executed cause the computer to perform the steps of:

converting a design cycle that characterizes a design activity into a plurality of alternate process steps for achieving a predefined goal of the design activity;

assigning estimated cost metrics to the alternate process steps;

executing the design cycle for at least one iteration;

replacing associated estimated cost metrics with actual cost metrics; and

using the actual cost metrics to calculate new estimated cost metrics.

39. The medium of claim 38, wherein the plurality of alternate process steps are contained in a graphical representation.

40. The medium of claim 39, wherein the estimated cost metrics are assigned between paths of the alternate process steps on the graph.

41. The computer readable medium of claim 40, wherein the steps performed further comprise:

optimizing the design cycle by selecting paths between the alternate process steps are assigned smaller estimated cost metrics;

receiving an indication of whether accuracy or speed is a more important design criterion; and

using the indication in the step of optimizing.

42. The computer readable medium of claim 41, wherein at least one of the process steps can be accomplished by a plurality of methods, and where the step of optimizing includes considering different costs of accomplishing the process step using different methods of the plurality of methods.

43. The medium of claim 38, wherein in the step of replacing associated estimated cost metrics with actual cost metrics is performed as process steps are completed in an iteration of the design cycle.