How to Perform a Step Test

Tuning PID controllers is a multi-step process.  While it is important to understand each step in the process, performing the bump test and collecting dynamic data is the most crucial step that generally dictates the outcome.  This post delves into one particular type of test – the Step Test – before introducing other tests commonly used in PID controller tuning.

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How Does the Derivative Term Affect PID Controller Performance?

Derivative is the third term within the PID. In mathematical terms the word derivative is defined as the slope of a curve. Seen in the context of strip chart data derivative represents the rate of change in error – the difference between the Process Variable (PV) and Set Point (SP). Like the proportional and integral terms within a PID controller, the derivative term seeks to correct for error. Valuable as the third term can be in maintaining effective control, experience suggests that appropriate uses of derivative are not entirely clear.

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