Curve Sketcher 1Ch

Curve Sketcher 1Ch identifies inversions (peaks and valleys) in an input data stream. Furthermore, local maxima of the absolute difference between two consecutive values (referred to as Delta) can be identified. Analogous to a continuous curve, the identified peaks and valleys correspond to local maxima and minima. Delta corresponds to the slope, so that a maximum of the absolute values of Delta can be associated with an inflection point.

Optionally, a Boolean signal can be selected for the Enable Execution input so that the algorithm is only active if the value of the selected signal is TRUE.

Configuration options

• Threshold Reversal: threshold for identifying reversals. Reversals are only detected if their difference from the next reversal exceeds the value of Threshold Reversal.
  Below are three examples of peak identification using the parameter Threshold Reversal.
  (a) The value y₃ is identified as a peak immediately after processing the value y₄ because the difference between y₃ and y₄ is greater than Threshold Reversal.
  (b) The value y₃ is not identified as a peak because the difference between y₃ and y₄ is smaller than Threshold Reversal and the curve starts rising again after y₄.
  (c) The value y₂ is identified as a peak after processing the value y₅ because the difference between y₂ and y₅ exceeds Threshold Reversal. The value y₂ cannot be identified as a peak beforehand because the difference between y₂ and y₃ (y₄) is less than/equal to Threshold Reversal and it is not known whether the values will continue to decrease.

• Threshold Delta: threshold for identifying Delta maxima. Maxima of the absolute difference of two successive values (delta) are detected only if the difference between successive deltas exceeds Threshold Delta.
  Below are three examples of identifying the Delta maxima with the parameter Threshold Delta . The upper diagrams show the original input signals, the lower ones the corresponding delta.
  (a) The value y₄ is identified as a maximum after processing the value y₅ because the difference between the two deltas exceeds Threshold Delta.
  (b) No maximum is identified because the difference between the deltas is less than Threshold Delta.
  (c) The value y₃ is identified as a maximum after processing the value y₆.

Regardless of Threshold Delta, at least one maximum of the Delta between two reversals is detected.

Output Values

• Last Peak: Indicates the y-value of the last identified peak.
• Time Last Peak: Indicates the timestamp of the last identified peak.
• Count Peaks: Indicates the total number of counted peaks.
• Last Valley: Indicates the y-value of the last identified valley.
• Time Last Valley: Indicates the timestamp of the last identified valley.
• Count Valleys: Indicates the total number of counted valleys.
• Value at Max Delta: Indicates the y-value of the analyzed stream (input variable) that is led by the last detected maximum of delta. The value delta is the difference between Value at Max Delta and the value that reached one cycle before.
• Max Delta: Indicates the last identified local maximum of the absolute difference between two successive values in the input stream.
• Time Max Delta: This is the timestamp of Value at Max Delta.
• Count Max Delta: Indicates the total number of counted local maxima of delta.

Standard HMI Controls

For the Curve Sketcher 1Ch algorithm, the following HMI controls are available for generating an Analytics Dashboard:

1. CurveSketcher control visualizes the output values Last Peak, Time Last Peak, Count Peaks, Last Valley, Time Last Valley, Count Valley, Last Delta, Time Last Delta and Count Delta as well as the input value of the data.

2. The Table Control visualizes all output values: Last Peak, Time Last Peak, Count Peaks, Last Valley, Time Last Valley, Count Valley, Value at Max Delta, Last Delta, Time Last Delta and Count Delta.

Alternatively, customer-specific HMI controls can be mapped in the Curve Sketcher 1Ch algorithm using the Mapping Wizard.