System has the gain of 1 if, for example, 50% of the input signal/variable causes the system output to achieve exactly 50%. Regarding the gain value, we need to look at it as to a relative value. Controlled system analysis stops here, though you might find that your controlled system is equivalent to the second-order system with the following transfer function (where the gain, K, is one for simplicity). From that ratio, users will be able to determine the order of the transfer function, and, in the case of the most common, second-order transfer function, you can find out both time constants. On the time (t) axis you should be able to mark two distinguished line segments, T u and T n. Now plot a tangent line going through the inflection point of the curve as it is shown in Figure 3.
#Computer simulation software
Courtesy: Peter Galan, a retired control software engineer What you will get will be very likely a “S” shaped curve as it is shown in Figure 3.įigure 3: Transfer function of controlled system is shown in an “S” shaped curve. The best way is to apply a step function at the input to the system and to capture and plot its time response. If you cannot mathematically describe your controlled system, treat it as a “black box” and find its transfer function by a different way. It sounds easy, but even for the simplest controlled system, like a servomechanism with a dc servo motor, it can take enormous amount of time to finalize its mathematical description. If you are designing the controlled system yourself, then you might be able to model (describe) it with a set of differential equations. For the control purposes, area of interest is the transfer function of the system, preferably in a well-known (s-domain) form: You need to extract as much information about the controlled system as possible. The first phase of a control system design is the controlled system (plant) analysis. Courtesy: Peter Galan, a retired control software engineer Control system design: System analysis Figure 2: Block diagram of digital closed-loop control system is shown.
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