System and method for compressing production data stream and filtering compressed data with different criteria

• US 9,116,907 B2
• Filed: 08/16/2013
• Issued: 08/25/2015
• Est. Priority Date: 08/16/2012
• Status: Active Grant

• Current Assignee: Siemens AG
• Original Assignee: Siemens AG
• Inventors: Olmino, Paolo
• Primary Examiner(s): Ruiz, Angelica
• Application Number:
  US13/968,612
• Publication Number:
  US 20140052701A1
• Time in Patent Office: 739 Days
• US Class Current: 1/1
• CPC Class Codes: G05B 19/058 Safety, monitoring
• CPC Class Codes: G05B 21/02 electric
• CPC Class Codes: G05B 2219/32404 Scada supervisory control and data acquisition
• CPC Class Codes: G06F 11/3082 the data filtering being achieved by aggregating or compressing the monitored data
• CPC Class Codes: G06F 16/1744 using compression, e.g. sparse files
• CPC Class Codes: G06F 16/24568 Data stream processing; Continuous queries

Abstract

Production data are streamed by a shop floor (a field) of a plant towards a data compression processor inside a MES/ERP server. The data stream is segmented in field data intervals of variable duration, each one carrying a tag composed of initial timespan s°, final timespan e°, and the variation v° undergone by the monitored variable. The processor takes a first incoming tag and calculates a data compression interval of constant duration y which is a function of e°, then it creates a vector [s°, e°, v°, m=v°, n=e°−s°]. Until the incoming tags fall into the current compression interval, subsequent variations v° are summed up and subsequent s° and e° updated, obtaining an updated vector [s, e, v, m, n], otherwise the compression vector is stored in a SQL database and a new compression interval entered.

Claims

1. A system for compressing a data stream coming from a shop floor defined as a field of a plant, the data stream being segmented in field data intervals, each of the field data intervals carrying a tag composed of at least a value v°

associated to a monitored variable and a timestamp when the monitored variable was recorded or calculated, the system comprising;

a first buffering device for temporarily storing tags coming from the field;

a programmable processing device containing firmware configured for having access to said first buffering device and taking the subsequent values v° and

accumulating the values within compression time intervals as summation data values v being compressed values v;

a second buffering device;

a database accessible by said programmable processing device for storing the compressed values v taken from said second buffering device;

a post-processing device for querying said database;

said firmware of said programmable processing device programmed to;

calculate an end value w of a current compression interval by means of the following function;

w(e°

)=z+ceiling[(e°

−

z)/y]×

y

in which;

z indicates a start of a compression process, y is a predetermined constant indicating a duration of each compression interval, e°

is a timestamp indicating an end of a current field data interval entering a current compression interval at first and further including a timestamp s°

indicating the start;

calculate a duration n=e°

−

s°

of a data interval entering the current compression interval at first; and

compare every subsequent timestamp e°

with the end value w and updating s°

, e°

until e°

≦

w is detected, as soon as the condition is false storing in said database a vector [s, e, v, v°

, n] wherein s, e, v, are updated s°

, e° and

accumulated v°

, and entering a new compression interval, a metric v°

/n constituting a multiplier usable, whenever requested, for linearly interpolating the value v°

across at least one of two ends of at least one filtering interval to be prefigured for postponed aggregation of entering compressed values v.

2. A method for compressing a data stream coming from a shop floor defined as a field of a plant, the data stream being segmented in field data intervals, each of the field data intervals carrying a tag composed of at least a value v°

associated to a monitored variable and a timestamp when the monitored variable was recorded or calculated, which comprises the steps of;

a) receiving tags sent from the field;

b) accumulating subsequent values v°

during a compression time interval to obtain summation data values defined as compressed values v, the step b) further including the sub steps of;

b1) calculating an end value w of a current compression interval by means of the following function;

w(e°

)=z+ceiling[(e°

−

z)/y]×

y;

in which;

z indicates a start of a compression process, y is a predetermined constant indicating a duration of each compression interval, e°

is a timestamp indicating an end of a field data interval entering a current compression interval at first and further including a timestamp s°

indicating the start;

b2) calculating a duration n=e°

−

s°

of a data interval entering the current compression interval at first;

b3) comparing every subsequent timestamp e°

with the end value w and updating s°

, e°

until e°

≦

w is detected, as soon as condition is false storing in the database during step c) a vector [s, e, v, v°

, n] wherein s, e, v, are updated s°

, e° and

accumulated v°

, and entering a new compression interval, a metric v°

/n constituting a multiplier usable, whenever requested, for linearly interpolating the value v°

across at least one of two ends of at least one filtering interval to be prefigured for postponed aggregation of entering compressed values v; and

c) storing the compressed values v in a database and repeating the steps a) to c) while a compression process is on-going.

3. The method according to claim 2, wherein an aggregation into filtering intervals avails of selectable filtering criteria depending on a positioning of a duration n in respect of boundaries of the filtering interval.

4. The method according to claim 3, which further comprises:

calculating a lower end a and an upper end b of the filtering interval such that (a−

z)/y and (b−

z)/y are integers;

whenever selected filtered criterion requires it, an interpolation of the value v°

at the lower end a is performed by multiplying v°

by a ratio between (a−

s°

) and (e°

−

s°

), while the interpolation at the upper end b is performed by multiplying v°

by a ratio between (b−

s°

) and (e°

−

s°

).

5. The method according to claim 4, wherein for the selected filtering criterion and for each compression interval a further aggregation is performed by accumulating respective linear combinations of contributions, each belonging to a subset of time slices overlapping to the compression interval, either totally or partially, and having associated a boundary condition of the filtering criterion.