CONTROLLER-DESIGN FOR NONLINEAR-SYSTEMS VIA DIFFERENT TRANSFORMATIONS

The designs of the level control in process flow systems with the type s of cylindrical, conical and hemispherical configurations are studied . All of the systems are non-linear and can be transformed to the line ar systems. However, we find that the transformation is not unique and that the non-linear output signal is also different depending on the choice of the transformation function. How to find a suitable transfor mation function is now investigated. First, we define the suitable tra nsformation function be integratable, invertable and effective. Then, define a sensitivity function for finding an appropriate form. Finally , by introducing a variable lambda(x) to the transformation function, one degree of freedom is obtained and two classes of suitable forms fo r transformation function are recommended. The simulation results demo nstrate that the same non-linear output responses with a better perfor mance can be obtained by the suitable choice of the transformation fun ction.