Genetic Algorithm for Decentralized PI Controller Tuning of a Multi-Span Web Transport System Based on Overlapping Decomposition

The use of multi-span web transport systems often requires dedicating a particular effort for defining a control system able to protect the integrity of the web. In web handling processes there is a clear need for controlling web velocity and tension. As for any control problem, the best results are achieved when there is a clear understanding of the controlled process. Starting from a new mathematical model called Transfer Matrix Model for a more accurate description of a web transport system, an optimization study for identifying parameters of the PI controllers for a decentralized multiinput and multi-output system (MIMO) has been proposed. The possibility of using PI controllers for each section is attractive considering that an overlapping system decomposition may permit to take into account the mutual interaction of the neighbor sections reaching specified performance objectives. Finally, by using a nonlinear interpolation of the trend of a preliminary database of values obtained through genetic algorithm, a self-tuning strategy is proposed to estimate optimal PI parameters under certain conditions, avoiding the long identification process and making the system flexible and adaptive. Simulations and experimental results validate and illustrate the effectiveness and the simplicity of the proposed method by considering several different set-points.The 2017 Asian Control Conference -ASCC 2017, December 17-20, 2017, Gold Coast Convention Centre, Australi

Implementation and Validation of a Lumped Model for an Experimental Multi-Span Web Transport System

Correct modeling is necessary in order to design a better control system or to identify the plant parameters experimentally. On the web dynamics itself, lumped parameters expressions may be used to designate a web section between two adjacent drive rolls, and there is the necessity of incorporating the property of viscoelasticity to the web. Lumped model of an experimental multi-span web transport system is based on the conservation mass, torque balance and viscoelasticity. A new way for describing this kind of MIMO system has been introduced through a four by four Transfer Matrix which considers mutual interactions between inputs and outputs. Finally, comparing experimental data with Transfer Matrix parametric expressions, it has been possible to identify the system parameters and thus fully validate the effectiveness of the proposed dynamic lumped model.The 2017 Asian Control Conference -ASCC2017, December 17-20, 2017, Gold Coast Convention Centre, Australi

A composite hydrogel for brain tissue phantoms

Synthetic phantoms are valuable tools for training, research and development in traditional and computer aided surgery, but complex organs, such as the brain, are difficult to replicate. Here, we present the development of a new composite hydrogel capable of mimicking the mechanical response of brain tissue under loading. Our results demonstrate how the combination of two different hydrogels, whose synergistic interaction results in a highly tunable blend, produces a hybrid material that closely matches the strongly dynamic and non-linear response of brain tissue. The new synthetic material is inexpensive, simple to prepare, and its constitutive components are both widely available and biocompatible. Our investigation of the properties of this engineered tissue, using both small scale testing and life-sized brain phantoms, shows that it is suitable for reproducing the brain shift phenomenon and brain tissue response to indentation and palpation