Variable transport delay modelling mechanism

• US 8,700,366 B1
• Filed: 05/14/2012
• Issued: 04/15/2014
• Est. Priority Date: 09/06/2005
• Status: Active Grant

• Current Assignee: The MathWorks, Inc.
• Original Assignee: The MathWorks, Inc.
• Inventors: Zhang, Fu, Yeddanapudi, Murali
• Primary Examiner(s): FREJD, RUSSELL WARREN
• Application Number:
  US13/470,891
• Time in Patent Office: 701 Days
• Field of Search: 703/2
• US Class Current: 703/2
• CPC Class Codes: G06F 17/10 Complex mathematical operations function generation by table look-up G06F1/03; evaluation of elementary functions by calculation G06F7/544

Abstract

A method, system and apparatus for managing data in a buffer reduces the data density of the buffer by downsampling input buffer data. The buffer holds a plurality of input data points associated with an index. The buffer may have a capacity and a data density that represents a logical distance between indices of adjacent input data points. When the buffer is at or near the capacity, a rule may be applied to the data buffer. The rule may downsample the input data and reduces the data density of the buffer. The rule may include, for example, removing every k^th input data point, or removing the least-used data points. Removed data points may be retrieved by deriving the removed data points from data points that remain in the buffer.

Claims

1. An electronic-device implemented method comprising:

interacting with a buffer using a processor of an electronic device, the buffer;

holding a plurality of input data points, the plurality of input data points being associated with a plurality of indices, the plurality of indices representing positions of the plurality of input data points with respect to each other,

having a capacity, and

having a data density representing a logical distance between indices of adjacent ones of the plurality of input data points;

identifying that the buffer is at or near a threshold,

the threshold related to the capacity of the buffer, and

the identifying performed using the processor of the electronic device; and

applying a rule to the buffer when the buffer is at or near the threshold, where the applying;

downsamples the plurality of input data points by removing at least one intermediate input data point from the buffer, and

reduces the data density of the buffer.

2. The method of claim 1, wherein the rule specifies removing every k^th K input data point from the buffer, where k is a positive integer.

3. The method of claim 1, wherein the rule comprises removing from the buffer a least-used data point that is a subject of a least number of requests from a requesting entity.

4. The method of claim 1, wherein the rule comprises removing from the buffer a least-used data point that is a subject of a least cumulative number of requests from a plurality of requesting entities.

5. The method of claim 1, wherein the data density represents an average distance between indices of adjacent ones of the plurality of input data points.

6. The method of claim 1, wherein the threshold is the capacity of the buffer.

7. The method of claim 1, further comprising:

receiving a request for a requested data point that is not stored in the buffer;

interpolating between two of the plurality of input data points stored in the buffer to derive the requested data point; and

returning the requested data point in response to the request.

8. The method of claim 1, wherein each index is associated with a time at which a respective data point was collected, and wherein the logical distance between the indices of the adjacent ones of the plurality of input data points is a temporal distance.

9. The method of claim 1, wherein the plurality of input data points represent a variable transport delay representative of delayed data provided to the buffer, the variable transport delay used by a dynamic system represented in a model by one or more differential equations.

10. The method of claim 9, wherein the variable transport delay is determined by:

identifying an initial time at which one of the plurality of input data points starts and an ending time at which the one of the plurality of input data points ends;

calculating an instantaneous time delay using the initial time, the ending time and the input data point;

integrating the instantaneous time delay; and

assigning the integrated instantaneous time delay as the variable transport delay.

11. A non-transitory device readable storage medium holding instructions, the instructions comprising:

instructions that, when executed by a processor of an electronic device, cause the processor to;

interact with a buffer, the buffer;

holding a plurality of input data points, the plurality of input data points being associated with a plurality of indices, the plurality of indices representing positions of the plurality of input data points with respect to each other,

having a capacity, and

having a data density representing a logical distance between indices of adjacent ones of the plurality of input data points;

identifying that the buffer is at or near a threshold,

the threshold related to the capacity of the buffer, and

the identifying performed using the processor of the electronic device; and

apply a rule to the buffer when the buffer is at or near the threshold, where the applying;

downsamples the input data by removing at least one intermediate input data point from the buffer, and

reduces the data density of the buffer.

12. The medium of claim 11, wherein the rule comprises removing every k^th input data point from the buffer, where k is a positive integer.

13. The medium of claim 11, wherein the downsampling of the plurality of input data occurs when the buffer is at the capacity.

14. The medium of claim 11, further holding instructions for:

receiving a request for a requested data point that is not stored in the buffer; and

interpolating between two of the plurality of input data points stored in the buffer to derive the requested data point; and

returning the requested data point in response to the request.

15. The medium of claim 11, wherein the plurality of input data points represent a variable transport delay representative of delayed data provided to the buffer, the variable transport delay used by a dynamic system represented in a model by one or more differential equations.

16. A system comprising:

a storage for storing a buffer; and

a processor for;

interacting with the buffer, the buffer;

storing a plurality of input data points, the plurality of input data points being associated with a plurality of indices, the plurality of indices representing positions of the plurality of input data points with resect to each other,

having a capacity, and

having a data density representing a logical distance between indices of adjacent ones of the plurality of input data points;

identifying that the buffer is at or near a threshold,

the threshold related to the capacity of the buffer, and

the identifying performed using the processor of the electronic device; and

applying a rule to the buffer when the buffer is at or near the threshold, where the applying;

downsamples the plurality of input data points by removing at least one intermediate input data point from the buffer, and

reduces the data density of the buffer.

17. The system of claim 16, wherein the rule comprises removing every k^th input data point from the buffer, where k is a positive integer.

18. The system of claim 16, wherein the downsampling of the plurality of input data occurs when the buffer is at the capacity.

19. The system of claim 16, wherein the processor further:

receives a request for a requested data point that is not stored in the buffer; and

interpolates between two of the plurality of input data points stored in the buffer to derive the requested data point; and

returns the requested data point in response to the request.

20. The system of claim 16, wherein the plurality of input data points represent a variable transport delay representative of delayed data provided to the buffer, the variable transport delay used by a dynamic system represented in a model by one or more differential equations.