A Design Procedure for Robust Actuator and Sensor Fault Detection

This paper considers the design of an integrated observer structure termed as Proportional Integral Fading Unknown Input Observer (PIFUIO). The advantages of PIO and UIO observers are used in robust fault detection. The UIO decouples the unknown input disturbance while PIO allows to estimates the faults. It is shown that the fading term of this observer plays a distinct role in reliable estimation of faults decoupled from the unknown disturbance or vice versa. The robust detection of sensor fault is also considered with the presence of unknown inputs. Indirect and direct design procedures for sensor fault detection are provided. Numerical examples are included to illustrate the advantage of PIFUIO

Optimal Tracking for Nonlinear Interconnected Dynamic Systems using State Dependent Riccati Equation

This paper considers the problem of optimal control of nonlinear single and multiple interconnected dynamic systems using state dependent Riccati equation (SDRE). SDRE method mimics the classical LQR method of optimal linear control for a large class of nonlinear systems. It relies on a non-unique factorization of nonlinear systems known as the state dependent coefficient (SDC) parametrization. The paper initially provides a comprehensive derivation of SDRE for a single nonlinear system represented by SDC. Then, the necessary equations are given for multiple interconnected dynamic system based on the generalized SDC representation. We show the effectiveness of SDRE method and compare it with the method of control law partitioning or the method of computed-torque control (CTC), which has been used in control of robotics manipulators. Illustrative examples are given to demonstrate the usefulness of SDRE method as applied to single and multiple interconnected inverted pendulum as well as robotic manipulator