tailieunhanh - Challenges and Paradigms in Applied Robust Control Part 13

Tham khảo tài liệu 'challenges and paradigms in applied robust control part 13', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 16 Robust Networked Control Wojciech Grega Department of Automatics AGH University of Science and Technology Poland 1. Introduction Most of integrated industrial control systems adopt a multilevel vertical control hierarchy. Logically such a system Fig. 1 is structured in three levels the direct device control level the supervisory level and the management level Grega 2010 Tatjewski 2007 Grega at al. 2009 . The basic task of the direct device control level is to maintain the process states at the prescribed set values. The device controller level provides an interface to the hardware either separate modules or microprocessors incorporated in the equipment to be controlled. Here mainly PID digital control algorithms are implemented - in some cases these are more advances control methods such as multivariable control or adaptive functions. A number of embedded control nodes and Programmable Logical Controllers PLC are used as the frontends to take the control tasks. High speed networks and fieldbuses are implemented at the direct control level to exchange in real time the information between front-ends and the device controllers and vertically with the supervisory control level. This architecture has the advantage of locating the hard real-time activities as near as possible to the equipment. Fig. 1. Multilevel structure of an industrial control system 350 Challenges and Paradigms in Applied Robust Control The supervisory level comprises workstations and industrial PCs providing high-level control support database support graphic man-machine interface network management and general computing resources. Classically the supervisory level calculates set points for controllers according to the defined criteria. For this purpose more complex mathematical models of the process are employed at this level to find the optimal steady-state by solving optimisation and identification tasks. Due to the rapid development of control technology there is growing scope for more .