Observer design for discrete nonlinear descriptor systems

• Published in: UKACC International Conference on Control. Control '96 pp. 831 - 836
• Main Author: Shields, D.N
• Format: Conference Proceeding
• Language: English
• Published: London IEE 1996
• Subjects: Algebra; Control system analysis and synthesis methods; Discrete control systems; Nonlinear control systems; Robotics; Simulation, modelling and identification; Stability in control theory; discrete time systems; nonlinear observer; flexible joint robot; nonlinear descriptor systems; quadratic Lyapunov function; Lipschitz nonlinearities; feedback; Riccati equations; nonlinear control systems; control nonlinearities; state estimation; robots; Riccati equation; observers; singular value decomposition; Lyapunov methods
• ISBN: 0852966660; 9780852966662
• DOI: 10.1049/cp:19960660

A nonlinear observer is considered for a class of discrete nonlinear descriptor systems subject to unknown inputs. This class is partly characterised by globally Lipschitz nonlinearities and a member system may be singular. First, the system is transformed into SVD-form from which a preliminary feedback control function can be designed, if needed, to render the system causal. Then a nonlinear observer is proposed which is based on the solution of a Riccati equation and on the use of a quadratic Lyapunov function. A design algorithm is given and applied to the estimation of the states of a flexible joint robot.