Atlas Copco PowerMACS 4000, User Manual

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Tightening
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6.5.3.5 Gradient
Parameters : Threshold Torque, Angle distance, No degrees, Gradient Low, Gradient High
Function : Calculates and checks the gradient of the torque curve, that is, the ratio of torque vs. angle.
The gradient is calculated as the difference in torque Angle distance apart divided by the
Angle distance. The first gradient is calculated Angle distance after Threshold torque has
been reached. A new gradient is calculated every time a new torque and angle sample is
available, that is, normally once every millisecond.
The calculated gradient is compared against the limits and stored in trace as a gradient
curve. One or both of the gradient limits can be left empty. If both are empty no restriction
check is active, but the calculated gradient is still stored in the trace.
The torque samples used for the gradient calculation are filtered using a sliding window
average filter. The No degrees parameter defines the sliding window angle over which
mean values are calculated.
In case the step runs backwards compared to the step direction the restriction ends the step
if limit is specified. If no limit is configured the gradient calculation is restarted and there is a
gap in the trace curve until the first new gradient can be calculated.