Edouard Richard

Design of reduced-order observers without internal delays

This paper provides a simple and systematic design method of reduced-order observers without internal delays for systems having a time delay in the state variables. Necessary and sufficient conditions for the existence of these observers are given.

Simultaneous observer based sensor diagnosis and speed estimation of Unmanned Aerial Vehicle

In this contribution we investigate the problem of simultaneous observer based sensor diagnosis and speed estimation of unmanned aerial vehicle (UAV). The main features lie in the use of a useful bank of reduced order observers to detect and isolate faulty sensors and in the same time to provide unbiased speed estimation of UAV from accelerometers. From a structural analysis, we provide all trajectories for which faults would be detected and estimated. The theoretical result is summarized into the stability analysis, established through the Lyapunov approach and Barbalat lemma. The existence condition is expressed in terms of physical variables of the UAV. Performances and easiness of implementation of the proposed technique are shown through a quadrotor UAV.

REDUCED-ORDER OBSERVER-BASED POINT-TO-POINT AND TRAJECTORY CONTROLLERS FOR ROBOT MANIPULATORS

This paper presents a design procedure for a reduced-order observer-based controller dedicated to n-joint robot manipulators. It is assumed that only the joint angular positions are measured. The joint angular velocities are estimated via an exponential reduced-order observer. Two types of control laws based on this observer are studied: point-to-point control with gravity compensation and trajectory control. Sufficient conditions to ensure the closed-loop stability are given. Performances of the reduced-order observer used with these two control laws are illustrated in a simulation study of a two-degrees-of-freedom robot manipulator.

Nonlinear Backstepping Based Trajectory Tracking Control of a Gun Launched Micro Aerial Vehicle

This paper considers the question of obtaining a nonlinear trajectory tracking control law for a comprehensive design of a Gun Launched Micro Aerial Vehicle (GLMAV), a new Micro Aerial Vehicle (MAV) concept using two bladed coaxial contra-rotating rotors. The MAV packaged in a projectile is launched using the energy delivered by a portable weapon. When it reaches the apogee, the projectile is transformed in such a way that the MAV becomes operational over the zone to be observed. A detailed GLMAV nonlinear mathematical model, taking into consideration external wind, is presented for hover and near hover flight conditions. The problem is di cult due to that external wind and to the presence of small body forces that can not be directly incorporated into the control design. A control Lyapunov function, used to analyze the closed loop performance of the system, is then derived for an approximate model using standard backstepping techniques. The whole design procedure of the backstepping based control law is conducted within the paper. This control law is then applied to the whole model of the GLMAV and a numerical simulation is used to demonstrate the control laws nominal performance. Following this, other numerical simulations are used to demonstrate the control law performance in presence of noise measurement and external wind. Finally, the designed nonlinear control law succeeds in enforcing the desired trajectories robustly with respect to noise measurement, external wind and approximations made in the modeling of the GLMAV.

H∞ Reduced-Order Output Feedback Controller For Trajectory Tracking Of Robot Manipulators

Abstract This paper is dedicated to trajectory tracking problem with disturbance attenuation (L2) in robotics systems via a reduced-order output feedback controller, without velocity measurement. This controller ensures both semi-global asymptotic stability of the closed-loop system and external disturbance attenuation.

Two robust static output feedback H ∞ control architectures for a Gun Launched Micro Aerial Vehicle

In this paper, the design process of two robust H∞ control architectures for a Gun Launched Micro Aerial Vehicle - GLMAV - is presented. The process starts with the developement of a nonlinear dynamic model reflecting the important elements of the GLMAV. This model is then linearized around hover and used for the design of static output feedback H∞ controllers for position and orientation control. Unlike the full-order H∞ controller synthesis case, the H∞ optimization problem of static output feedback (SOF) controllers cannot be parameterized as a convex optimization problem. The cone complementarity linearization algorithm is therefore used to overcome the nonconvexity problem due to the constraint on the controller order. Finally, numerical simulations show the efficiency of the designed controllers.

Disturbance Attenuation Via a Reduced-Order Output Feedback Controller for Rigid Robotics Manipulators

Abstract This note presents a solution to the problem of external disturbance attenuation in robotics systems via a reduced-order output feedback controller. The proposed controller based on a point-to-point control law ensures both asymptotic stability of the equilibrium point of the robot system and external disturbance attenuation. The approach is based on the notion of the L 2 -gain.

Reduced-order H/sub /spl infin// observer for robot manipulators

This paper discusses a design procedure of an asymptotic reduced-order H/sub /spl infin// observer for a n-joint rigid robot manipulator. The possibility of estimating the joint angular velocities via the proposed observer is investigated, which provides an asymptotic convergence of the reconstruction error, and attenuates the effect of the external disturbances on the robot model.