лур / Symbolic Algebra Tools

SYMBOLIC ALGEBRA TOOLS FOR CONTROL TEACHING

Symbolic algebra languages offer an exciting opportunity for the development of online teaching aids. Some of the facilities have been developed to support the teaching of control engineering concepts, using Mathematica. The type of user-interface facilities that can be created and the ease with which control manipulations can be carried out are presented.

Accuracy is a major problem in various computing tasks which arise in scientific and engineering studies. While most modern numerical subroutine libraries on linear algebra, which are widely used in control system CAD, are generally good at producing results with no large errors. There are many occasions where large errors or failures, can occur due to the numerical sensitivity of the data concerned. Symbolic algebra languages, such as Mathematica and Maple, all handle fractional numerical forms with infinite precision. Thus, working with symbols, where necessary, and rational numbers, cancellation and simplification of sub-expressions are more readily performed, giving enhanced accuracy, performance and code simplification. This now allows many of the more compact results, which have emerged from algebraic systems theory and rely on the accurate manipulation of polynomial functions, to be implemented.

There are also many occasions, in the implementation of algorithms, where numerical approximations are used because the symbolyc tools available cannot directly handle even simple differential and integral equations.

These latter functions cannot only be handled exactly in symbolic form, but also in many cases need only be done once for a whole class of systems. Such situation can arise in the modeling analysis, design or optimization aspects of control systems.