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A neural network (NN)-based compensation control is proposed for the trajectory tracking of robotic manipulators with unknown dynamics. This compensation controller includes a PD feedback controller, a nonlinear feedback controller and a neural network compensator with input modification. The PD controller and the nonlinear feedback controller are used to ensure the stability of the robot system,...
The stabilization problem of an underactuated surface vessel is addressed in this paper. A discontinuous control approach with two stage control laws switched on at given time is proposed based on the stability analysis of the global transformed system. With the aid of terminal sliding mode (TSM) method, the two asymptotically stabilizing control laws for the transformed subsystems are designed independently...
This paper considers the use of higher order sliding mode observers to address the problem of actuator fault estimation in a satellite leader/follower system. It is argued that if only relative position information between the leader and follower spacecraft is available, the problem of reconstructing an actuator fault signal, modelled as an additive unknown input to the system, represents one of estimating...
This paper presents a robust fault detection and diagnosis (FDD) scheme for abrupt and incipient faults in a class of nonlinear dynamic systems. A nonlinear observer which synthesizes second order sliding mode techniques and wavelet networks is proposed for online monitoring. The second order sliding mode is designed to eliminate the effect of system uncertainties on the state observation. Moreover,...
In this paper, a new approach to estimation of unknown inputs and faults in a class of nonlinear systems is presented. The approach is based on the design of a cascade connection of two sliding mode observers. The first is used for estimation of state and unknown inputs and the second is used for fault detection. An important feature of the proposed approach is that the state trajectories do not leave...
The problem of trajectory tracking by means of dynamic partial state feedback for the kinematic model of the unicycle mobile robot is addressed and solved. It is shown that the combination of a classical dynamic full information controller with an exponentially stable angular attitude estimator, designed using the immersion and invariance technique, yields a locally asymptotically stable closed-loop...
In this paper, adaptive variable structure neural control is investigated for a class of uncertain SISO nonlinear systems in a Brunovsky form with state time-varying delays and unknown dead-zone input. The unknown time-varying delay uncertainties are compensated for using appropriate Lyapunov-Krasovskii functionals in the design. The approach removes the assumption of linearity function outside the...
An autopilot design for autonomous closed-coupled formation flight of aircrafts is considered and addressed via quasi-continuous high order sliding mode control (HOSM.) The proposed HOSM-formation flight autopilot provides the trailing aircraft with bounded, continuous output tracking and minimizes effects of vortex uncertainty on the aircraft aerodynamic drag force. The performance of the proposed...
In this paper, we discuss the classical problem of attitude stabilization for a rigid spacecraft with external disturbances. Almost all the control laws for attitude stabilization problem in the literature can only guarantee at best exponential convergence of the attitude with infinite settling time. We employ finite-time control techniques including terminal sliding mode approach and continuous finite-time...
In this paper, we propose a design of an active-queue-management (AQM) scheme based on delay dependent sliding-mode-control (SMC), which is aimed at robust stabilization of network system with delay in both the input and state variables. A sliding surface that is based on a predictor has been designed to minimize the effect of the input delay. An AQM controller is derived to ensure the existence of...
Electrostatic force generation in MEMS Lateral Comb Resonators is not a function of the distance of the stationary and the moving plate (shuttle) in the direction of the movement. However, manufacturing imperfections and sometimes faulty conditions make the device operate asymmetrically which cause the rotational movement, orthogonal to the conventional direction of movement and put the device in...
To achieve fast and agile missile flight, carefully designed micro-actuated flow effectors relying on smart structures is a promising technology thanks to their compactness and lightweight properties. Indeed, micro- actuated flow effectors are ideal candidates to carry out active flow control. Such effectors can be mounted on a compliant mechanism and be actuated by means of antagonistic shape memory...
A higher order sliding mode observer is proposed to estimate exactly the observable states and asymptotically the unobservable ones in MIMO nonlinear systems with unknown inputs and stable internal dynamics. In addition the unknown inputs can be identified asymptotically. Numerical examples illustrate the efficacy of the proposed observer.
The notion of fractal dynamics is introduced, and a conjecture is formulated that the character of parasitic dynamics of real control systems is fractal. This property is particularly important for sliding mode (SM) control systems. A model of fractal dynamics is proposed. The characteristics of fractal dynamics are studied in the frequency and time domains. It is shown that due to the fractal nature...
The control problem of nonlinear discrete-time systems based on the Takagi-Sugeno (T-S) fuzzy model was addressed. A nonlinear system dynamic model is represented by a T-S fuzzy model. The global T-S fuzzy model of nonlinear system was transformed into linear uncertain system model. So the stabilization problem of nonlinear systems becomes the robust stabilization problem of linear uncertain systems...
An output feedback sliding mode controller was recently introduced for linear uncertain systems with unknown control direction based on monitoring functions. Nonlinear systems were also considered but restricted to output dependent nonlinearities. Global or semi-global exact output tracking was obtained. Here, generalization is achieved to include nonlinearities depending on unmeasured states and...
A dynamical sliding-mode control is used to avoid different bit sticking problems present in a conventional vertical oilwell drillstring. The control goal of driving the rotary velocities of drillstring components to a constant positive value is achieved by means of this control. A discontinuous lumped- parameter torsional model of four degrees of freedom is considered. This model allows to describe...
This paper is about the application of second order sliding mode control to solving automatic space docking problem. Two problems are considered herein, first the establishment of a close formation by the steering of the last stage thrust engine, and its proper termination, and then the docking by itself using centre of gravity and attitude thrusters. The design is based on a combination of second...
This paper describes a robust nonlinear control approach for modern diesel engines having multiple combustion modes in particular low temperature combustion (LTC) and conventional diesel combustion. An innovative hybrid control system is designed to track different key engine operating variable sets at different combustion modes as well as avoid singularity which is inherent for turbocharged diesel...
This paper presents sliding mode pulse width modulation (SMPWM) control methodologies for a current- controlled inverter. Discussion begins with circuit analysis, proper references, and design of sliding surfaces. Based on this formulation, two novel approaches adopt sliding mode concept are proposed to make the system tracking selected references. Three-phase currents and the neutral point voltage...
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