Robust Adaptive Controller and Observer Design for a Class of Nonlinear Systems with Unknown Backlash- Like Hysteresis

in 2011 IEEE International Conference on Control System, Computing and Engineering (2011, November)

This paper presents a controller and observer design for a class of nonlinear systems that have: i. the coupling of the unmeasured states and unknown parameters ii. unknown Backlash- Like Hysteresis (BLH ... [more ▼]

This paper presents a controller and observer design for a class of nonlinear systems that have: i. the coupling of the unmeasured states and unknown parameters ii. unknown Backlash- Like Hysteresis (BLH) at its actuation. Firstly, we use a developed mathematical model of the BLH in which the BLH is cast into two terms; a linear term and a bound. Then a robust adaptive control law, unmeasured states observer, and unknown parameters estimator are designed such that global stability is achieved for all signals involved. Using the suggested scheme, simulation is carried out for a single- link mechanical system with a BLH exist at its actuation and dynamic friction torque exerts on the joint. Excellent tracking performance is obtained through the suggested approach and all closed loop signals are bounded. [less ▲]

Robust Control Design for Spacecraft Attitude Systems with Unknown Dead Zone

in 2011 IEEE International Conference on Control System, Computing and Engineering (2011, November)

In this paper, we consider the challenge of controlling inherently complicated nonlinear systems accompanied by input's hard nonlinearities characterized by unknown parameters. This challenge is addressed ... [more ▼]

In this paper, we consider the challenge of controlling inherently complicated nonlinear systems accompanied by input's hard nonlinearities characterized by unknown parameters. This challenge is addressed in this paper by considering the problem of controlling the attitude of a spacecraft when unknown dead zones exist at the actuators. The spacecraft's dynamics is described by the exact form of Euler's equations of motion, allowing for the case of large angle of rotations to be considered. We propose a control scheme that ensures the spacecraft's attitude to track time-varying maneuvers with an exponential tracking error convergence and robustness to actuator dead zones uncertainties. Numerical simulation results along with the theoretical proof show that the proposed control scheme can successfully stabilize the attitude of the spacecraft and achieve the desired tracking performance. [less ▲]

Adaptive Sliding Mode Control Design for a Class of Nonlinear Systems with Unknown Dead Zone of Unknown Bounds

in Abstract book of 1st International Conference on Energy, Power, and Control (2010, December)

The control problem for a class of nonlinear systems that contain the coupling of unmeasured states and unknown parameters is addressed. The system actuation is assumed to suffer from unknown dead zone ... [more ▼]

The control problem for a class of nonlinear systems that contain the coupling of unmeasured states and unknown parameters is addressed. The system actuation is assumed to suffer from unknown dead zone nonlinearity. The parameters bounds of the unknown dead zone to be considered are unknown. Adaptive sliding mode controller, unmeasured states observer, and unknown parameters estimators are suggested such that global stability is achieved. Simulation for a single link mechanical system with unknown dead zone and friction torque is implemented for proving the efficacy of the suggested scheme. [less ▲]

Stable Robust Adaptive Control of a Robotic Manipulator with Unknown Dead Zone and Friction Torques

in World Academy of Science, Engineering and Technology (2010)

The problem of controlling a two link robotic manipulator, consisting of a rotating and a prismatic links, is addressed. The actuations of both links are assumed to have unknown dead zone nonlinearities ... [more ▼]

The problem of controlling a two link robotic manipulator, consisting of a rotating and a prismatic links, is addressed. The actuations of both links are assumed to have unknown dead zone nonlinearities and friction torques modeled by LuGre friction model. Because of the existence of the unknown dead zone and friction torque at the actuations, unknown parameters and unmeasured states would appear to be part of the overall system dynamics that need for estimation. Unmeasured states observer, unknown parameters estimators, and robust adaptive control laws have been derived such that closed loop global stability is achieved. Simulation results have been performed to show the efficacy of the suggested approach. [less ▲]

Stable Robust Adaptive Controller and Observer Design for a Class of SISO Nonlinear Systems with Unknown Dead Zone

in 2009 International Conference on Control and Automation (2009, November)

This paper presents a new stable robust adaptive controller and observer design for a class of nonlinear systems that contain i. coupling of unmeasured states and unknown parameters ii. unknown dead zone ... [more ▼]

This paper presents a new stable robust adaptive controller and observer design for a class of nonlinear systems that contain i. coupling of unmeasured states and unknown parameters ii. unknown dead zone at the system actuator. The system is firstly cast into a modified form in which the observer and parameter estimation become feasible. Then a stable robust adaptive controller, state observer, parameter update laws are derived that would provide global adaptive system stability and desirable performance. To validate the approach, simulation was performed to a single-link mechanical system with a dynamic friction model and unknown dead zone exists at the system actuation. Then a comparison is presented with the results when there is no dead zone at the system actuation. [less ▲]