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Default Out-of-the-Box Settings Prevent the PID Controller from Achieving its Goal
Tuning a PID controller doesn’t have to be hard. Whether a practitioner chooses to tune control loops manually or with the help of software, the procedure is relatively straight forward and can produce highly effective results. It can be argued that using software is faster and provides more optimal results than manual tuning, but that’s an argument that largely depends on the economic importance of the PID control loop in question. In the end, the goal is the same: To tune for improved control loop performance.
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.
How Often Should PID Control Loops be Tuned?
When it comes to PID control loops and the right time for tuning practitioners generally fall into one of two camps. There is the group that adheres to a philosophy whereby PID control loops should be tuned more or less every year. That’s that. No debate. And there is another group that believes the answer for control loop tuning isn’t so cut and dried. From their perspective, it depends on the loop. It varies based on conditions. There is wisdom in both of these viewpoints.
How Do I Calculate Dead-Time?
Adults can learn a thing or two from children. That’s especially true when it comes to matters of time. Whereas adults view it as fashionable to show up to a social event 15 or more minutes late, children can’t wait to go and be a part of the action. When at a theme park adults typically their time strolling from place to place while children know that each minute of delay can cost hours longer in line. Simply put: When it comes to time every second matters. That viewpoint seems highly relevant to process control, control loop tuning, and calculating Dead-Time. Dead-Time is generally the model parameter that’s easiest to calculate when tuning a PID controller.