This paper presents the mathematical modeling and the design of an optimal pressure tracking controller for an often used setup in pneumatic applications. Two pneumatic chambers are connected with a pneumatic tube. The pressure in the second chamber is to be controlled using two switching valves connected to the first chamber and based on the pressure measurement in the first chamber. The optimal control problem is formulated and solved using the MPC framework. The designed controller shows good tracking quality, while fulfilling hard constraints, like maintaining the pressure below a given upper bound.

MELO, F. E. M. Modeling and linear parameter-varying identification of a two-tank system. 2017. 82 f. Dissertação (Mestrado em Engenharia Elétrica)–Centro de Tecnologia, Universidade Federal do Ceará, Fortaleza, 2017. / Submitted by Marlene Sousa (mmarlene@ufc.br) on 2017-09-06T17:29:24Z No. of bitstreams: 1 2017_dis_femmelo.pdf: 6250467 bytes, checksum: 7ec83fc628244552eb74ae6b40c6fbc0 (MD5) / Approved for entry into archive by Marlene Sousa (mmarlene@ufc.br) on 2017-09-06T17:30:18Z (GMT) No. of bitstreams: 1 2017_dis_femmelo.pdf: 6250467 bytes, checksum: 7ec83fc628244552eb74ae6b40c6fbc0 (MD5) / Made available in DSpace on 2017-09-06T17:30:18Z (GMT). No. of bitstreams: 1 2017_dis_femmelo.pdf: 6250467 bytes, checksum: 7ec83fc628244552eb74ae6b40c6fbc0 (MD5) Previous issue date: 2017-07-18 / This work addresses the modeling and the linear parameter-varying (LPV) system identification of a coupled two-tank system (TTS). The system is a multiple input multiple output (MIMO) with two inputs and two outputs. In order to obtain a suitable model for this system, a first-principle approach based on the mass balance principle is followed. It turns out that the modeling process was driven by the geometrical shape of the tanks. Thus, most of its parameters are based on the tanks’ dimensions. When it comes to the LPV identification, several methods are presented ranging from the classical results from the regression approach to the current support vector machines (SVM) based methods. All the identification algorithms presented are extended in order to cope with the MIMO systems. Additionally, a method based on instrumental variables support vector machines was adapted from the general nonlinear case to the LPV case. A new LPV model with two independent scheduling variables is proposed driven by prior knowledge on the process model. The results obtained with this new LPV model have showed a good performance in describing the TTS behavior. Furthermore, they were better than an LPV model considering only a single scheduling variable. / Este trabalho lida com a modelagem e identificação com abordagem de sistemas com parâmetros variantes (LPV) de um sistema de dois tanques acoplados (TTS). Esse sistema é do tipo múltipla entrada múltipla saída (MIMO) com duas entradas e duas saídas. Com a finalidade de obter um modelo adequado para esse sistema, é feita uma abordagem fenomenológica baseada no princípio do balanço de massa. Descobre-se que o processo de modelagem é dependente da forma geométrica dos tanques. Assim, a maioria dos seus parâmetros são baseados nas dimensões dos tanques. Quando se trata de identificação de sistemas LPV, vários métodos são apresentados desde os resultados clássicos baseados em regressão até os métodos atuais baseados em máquinas de vetor de suporte. Todos os algoritmos de identificação apresentados são estendidos para lidar com sistemas MIMO. Além disso, um método baseado em variáveis instrumentais com máquinas de vetor de suporte foi adaptado do caso não linear geral para o caso LPV. Um novo modelo LPV com duas variáveis de scheduling é proposto baseado em conhecimento a priori no modelo do processo. Os resultados obtidos com esse novo modelo LPV mostraram bom desempenho ao descrever o comportamento do sistema de dois tanques. Ademais, eles foram melhores do que um modelo LPV considerando apenas uma variável de scheduling.

This paper presents the mathematical modeling and the design of an optimal pressure tracking controller for an often used setup in pneumatic applications. Two pneumatic chambers are connected with a pneumatic tube. The pressure in the second chamber is to be controlled using two switching valves connected to the first chamber and based on the pressure measurement in the first chamber. The optimal control problem is formulated and solved using the MPC framework. The designed controller shows good tracking quality, while fulfilling hard constraints, like maintaining the pressure below a given upper bound.