Tu Duc Nguyen

Observer design for a flexible robot arm with a tip load

In this paper, we consider the observer design for a flexible robot arm with a tip load. The robot arm is modeled as an Euler-Bernoulli beam. The beam is clamped to a motor at one end and attached to a force actuator at the other. Based on measurements at the boundaries, an exponentially stable observer is proposed. The existence, uniqueness and stability of solutions of the proposed observer are based on semigroup theory. Numerical simulation results are included to illustrate the performance of the proposed observer.

Tracking and observer design for a motorized Euler-Bernoulli beam

In this paper, we consider the planar tracking problem and the observer design for an Euler-Bernoulli beam, clamped to a motor at one end and to a force actuator at the other. The control law for the motor is based on cancellation of terms at the boundary such that the desired error dynamics are obtained, and the control law for the force actuator is chosen such that the energy is extracted from the system. We also propose an exponential stable observer. The convergence of the observer is unaffected by the control laws. The stability analysis of the controlled system and the convergence of the observer are based on the semigroups theory. Numerical simulation results are included to illustrate the performance of the proposed control laws and the proposed observer. The simulation results are in agreement with the theoretical results.

Output tracking control of a flexible robot arm

In this paper, we address the problem of output feedback tracking control of a. The robot arm is modeled as an Euler-Bernoulli beam. The beam is clamped to amotor at one end and attached to a force actuator at the other. Based on measurements at the boundaries, a uniformly exponentially stable observer is proposed. Using the information from the observer, a tracking controller which allows the robot arm to follow time-varying references and damp out the elastic vibrations is designed. The existence, uniqueness and stability of solutions of the closed loop system and the observer are based on semi group theory. Numericals imulation results are included to illustrate the performance of the proposed control laws and the proposed observer. The simulation results are in agreement with the theoretical results.

Stabilization of towed cables

In this paper, we consider the stabilization problem for towed cables. The dynamics of the cables are described by nonlinear partial differential equations. The dynamics of the depth controllers are given by ordinary differential equations. Based on measurements at the depth controllers, exponential stable control laws are proposed. The stability analysis of the closed loop system is based on Lyapunov theory. The existence and uniqueness of solutions of the closed loop system are based on semigroup theory.

Modelling and Control of Offshore Marine Pipeline during Pipelay

Abstract A model suited for control tasks is developed for a submerged offshore pipe during the pipelay operation. The pipe is fixed in the touchdown point at the seabed in one end and attached to a pipelay vessel in the other end. The developed model is discrete and is on the form of the robot equation with minimal coordinates. Thus the methods of controller synthesis and stability analysis can be applied directly. The model constitutes a hyper redundant system and it is shown that this system is passive. A PID-controller has been suggested. The simulation results are in agreement with the theoretical results.

Second-order Observer for a Class of Second-Order Distributed Parameter Systems

This note addresses the observer design problem for a class of second order distributed parameter systems. Particularly, second order distributed parameter systems without distributed damping (or non-strictly positive distributed damping) are studied. Based on finite number of measurements, exponentially stable observer is designed. The existence, uniqueness and stability of solutions of the observer are based on semigroup theory. The developed procedure is illustrated via an example. Numerical simulation results are included. Simulation results are in agreement with the theoretical results

Output Feedback Stabilization of a Class of Second-Order Distributed Parameter Systems

This note addresses the output feedback stabilization problem for a class of second order distributed parameter systems. Particularly, second order distributed parameter systems without distributed damping (or non-strictly positive distributed damping) are studied. By following the same approach as in the previous work of the authors (2005), exponentially stable observer and controller are designed. The main analysis tool is semigroup theory. The results are illustrated via an example

Output Feedback Stabilization of Towed Marine Cable

This paper addresses the output feedback stabilization of towed marine cable. We consider a towed marine cable, attached to depth controllers at both ends. The dynamics of the cable are described by a nonlinear partial differential equation, adopted from (Ersdal [2004] and Kennedy [1987]). The dynamics of the depth controllers are given by ordinary differential equations. Based on boundary measurements, exponentially stable observer is designed. Using the information from the observer and boundary measurements, exponentially stabilizing controllers are proposed. The observer and controllers depend only on boundary measurements, the costs are thus minimized and spillover instability is avoided.

Observer design for a towed seismic streamer cable

Abstract In this paper, observer design for a towed seismic streamer cable is considered. Based on measurements at the boundaries, an uniformly exponentially stable observer is proposed. The stability analysis of the observer is based on Lyapunov theory. The existence and uniqueness of the solutions of the observer are based on semigroup theory. To illustrate the performance of the observer, numerical simulation results are presented.

Observer for Euler-Bernoulli beam with hydraulic drive

It is shown how to extend passivity and contraction results for flexible mechanisms with electrical drives to systems with hydraulic drives.