Abstract
Is investigated the accuracy of the transition from a continuous system to a discrete system for various variants of approximation of continuous links with discrete ones, as well as the magnitude of the sampling step and the degree of turn aside of the structural scheme of the system. The research is conducted on the example of a system consisting of an object and two proportional-integral-differential regulators.In our case, the object is unstable, representing an inverted pendulum on a trolley with one input and two outputs.The first regulator stabilizes the angle of deviation of the pendulum, and the second regulator fulfills the predetermined position of the trolley.This system is considered in many works, and in our case we consider the transition from a continuous system to a discrete one and is analyzed the discrepancy of transient processes.To switch from a continuous system to a discrete one, you can use several methods.For example, replace the integrator block on a discrete block by using the "zoh" commands – zero order hold and "foh" – fast order hold for different sampling steps.Are shown transitional processes of a continuous and discrete system are given. Also, is shown transition process to the system in the case of use transfer functions of the entire system "input-output" to discrete ones.When sampling, simulation errors are not significant.When the folding of the structural scheme, sampling errors decrease. Also, with a decrease in the sampling step, errors are reduced.

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