| "Modern control engineering" is a compulsory course in mechanical engineering. The application of state-space method not only deepens the cognizance of some important problems in control areas, but also makes people solve multi-input-multi-output systems more easily. And it provides the method of generalizing the conclusion of linear invariant system to complex system. But for the students it is difficult to master the mathematical model in state space state equation. So it is urgently to visualize the abstract theory through experimental ways and deepen the students'understanding of modern control theory. As to modern control theory mainly based on state equation, it could not take experiment through the practical experiments instruments. But with the development of science and technology, the union of computer technology, equipment technology, digital signal processing technology, standard bus technology and software engineering technology started a new milestone of virtual instrumentation instrument technology, so we can construct the virtual experimental system of modern control engineering with the strongly analytical skill of computer to finish the experiment.The virtual experimental system of modern control engineering uses LabVIEW 8.60 software and Control Design and Simulation toolkit. At present LabVIEW software developed by the American NI company is the most popular platform for virtual instrument's development. Its most characteristic is to use a graphical program mode. The virtual experimental system mainly introduced the five basic concept or theorem in modern control engineering and their experimental analysis, including the experiment about the interchange between modern control engineering's mathematical model-state space and classical control engineering's mathematical model-transfer function; the experiment about achieving the discretization of linear continuous system; the experiment about judging a system's controllability and observability according to the system's state equation; the experiment about getting the state feedback matrix and the state equations bringing observer through using the pole collocation method; the experiment about judging the stability of a system based on the lyapunov stability theory. Finally, through analysing the actual APC system, virtual experimental system further demonstrates the application of modern control engineering.As this virtual experiment system should include a lot, the design of overall structure uses subpanel technology and transfers the subroutine through the combination of event structure and button. And through the combination of enum constant, queue-ActiveX and the shift register of while cycle, we solve the conflict when transferring different subroutines. In addition in the design of how to transfer the subroutine, we use a series of functions about build path, strip path, in order to simplify the transfer. Finally in order to make interface aesthetics, we set the properties of window and the color and display mode of different ActiveX.Every design of experiment adopted the series of VI procedures in the control design and simulation kit, such as the experiment about mathematical model uses "Convert to State-Space Model VI" and "Draw State-Space Equation VI" to achieve shifting transfer function to state equation.This virtual experimental system is simple and easy to operate. It is fully compatible with the course of modern control engineering. Now it has been applied to teaching, and received a good result. Its various experiments help students understanding those boring mathematical theory deeply. And it also can strengthen the students'perceptual knowledge, improve the interest about learning.The widespread use of computers in schools also indicated that by using computer to develop a suitable virtual experimental system of modern control engineering has a great development prospects. And it is also the direction of future development to the universities'laboratory. |
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