Authors:
Przemyslaw Ignaciuk
and
Michał Morawski
Affiliation:
Lodz University of Technology, Poland
Keyword(s):
Nonlinear Control, Sampled-Data Systems, Variable Structure Control, Actuator Saturation.
Related
Ontology
Subjects/Areas/Topics:
Computer and Microprocessor-Based Control
;
Informatics in Control, Automation and Robotics
;
Nonlinear Signals and Systems
;
Signal Processing, Sensors, Systems Modeling and Control
Abstract:
In the effort to achieve high convergence rate, at the same time avoiding implementation difficulties and poor robustness of time-optimal controllers, the concept of soft Variable Structure Control (VSC) may be applied. The classical formulation of soft VSC in continuous time domain assumes smooth switching among an infinite number of controllers. Since nowadays control laws are implemented digitally, changing the control structure is limited to sampling instances, which leads to quasi-soft VSC. The paper investigates how the favourable characteristics of dynamic soft VSC can be extended to input-constrained systems with finite sampling. The design procedure and stability analysis are conducted directly in discrete time domain. The resulting nonlinear control law is synthesised into a form substantially different from its continuous-time counterpart. However, smooth control action and fast convergence of continuous soft VSC is retained. The properties of the obtained control system a
re formally proved and confirmed experimentally.
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