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Re: PID Loops
When looking at the LV VI, be a little careful that it doesn't add to the confusion. You know how there are multiple formulas for computing the slope of a line? Well there are multiple ways to write the formula for a PID.
The one most often used in robotics is called the parallel form or ideal form, and the terms are independent and the P, I, and D coefficients are all multiplied gains.
The LV VI implements the academic form or standard form, the one most often used for industrial plant control. The proportion gain affects the I and D results as well, and the I and D coefficients are time based and the I coefficient is a divisor instead of a gain. The time units are long because the processes often change slowly, and convention is to use seconds.
The wikipedia article (near the bottom) covers the conversions and some of the other implementation techniques in the LV one that make it more stable for industry.
By the way, we are considering including both forms and a number of additional control tools in the future. Any feedback or requests?
Greg McKaskle
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