Rigid body models with two controls cannot be locally asymptotically stabilized by continuous sta... more Rigid body models with two controls cannot be locally asymptotically stabilized by continuous state feedbacks. Existence of a locally stabilizing smooth time-varying feedback has however been proved. Here, such a feedback is ezplicitely derived.
In this paper we deal with robust control of a class of nonlinear systems which contain uncertain... more In this paper we deal with robust control of a class of nonlinear systems which contain uncertainties. It can be viewed as an extension of the work in Corless and Leitmann [IEEE Trans. Aurom. Conrrol, AC-Xi, 1139-1144 (1981)] for the cases where the vector of uncertainties is only partially known. To cope with the uncertainties, an adaptive controller using a dead-zone and a hysteresis function is proposed, and both the uniform boundedness of all the closed-loop signals and uniform ultimate boundedness of the system state are guaranteed. In contrast with some previous attempts to relax the a priori knowledge on the uncertainties bounds by using a discontinuous control law, we propose continuous control laws in this paper. Hence, chattering problems (which have practical importance) can be avoided.
It is known that rigid body models with two controls cannot be locally asymptotically stabilized ... more It is known that rigid body models with two controls cannot be locally asymptotically stabilized by continuous feedbacks which are functions of the state only. This impossibility does no longer hold when the feedback is also a function of time, or when it is discontinuous. A locally stabilizing smooth time-varying feedback is here explicitly derived by using Center Manifold Theory combined with averaging and Lyapunov techniques.
2018 IEEE Conference on Control Technology and Applications (CCTA), 2018
This paper addresses the problems of estimating the position of an object moving in $n(\geq\ 2)$ ... more This paper addresses the problems of estimating the position of an object moving in $n(\geq\ 2)$ -dimensional Euclidean space using possibly biased velocity measurements and possibly biased range measurements of one or multiple source points. The proposed solutions exploit the Continuous Riccati Equation (CRE) to calculate observer gains yielding global uniform exponential stability of zero estimation errors. These results are obtained under persistent excitation (p.e.) conditions whose satisfaction i) depends on the number and relative positioning of source points and on the object motion properties, and ii) ensures uniform observability and good conditioning of the CRE solutions. In particular, these conditions can be satisfied in the case of a single source point and a moving object. Simulation results illustrate the performance of the proposed observers in this latter case.
2018 IEEE International Conference on Robotics and Automation (ICRA), 2018
This paper revisits the problem of estimating the attitude, linear velocity and depth of an IMU-C... more This paper revisits the problem of estimating the attitude, linear velocity and depth of an IMU-Camera with respect to a planar target. The considered solution relies on the measurement of the optical flow (extracted from the continuous homography) complemented with gyrometer and accelerometer measurements. The proposed deterministic observer is accompanied with an observability analysis that points out camera's motion excitation conditions whose satisfaction grants stability of the observer and convergence of the estimation errors to zero. The performance of the observer is illustrated by performing experiments on a test-bed IMU-Camera system.
Rigid body models with two controls cannot be locally asymptotically stabilized by continuous sta... more Rigid body models with two controls cannot be locally asymptotically stabilized by continuous state feedbacks. Existence of a locally stabilizing smooth time-varying feedback has however been proved. Here, such a feedback is ezplicitely derived.
In this paper we deal with robust control of a class of nonlinear systems which contain uncertain... more In this paper we deal with robust control of a class of nonlinear systems which contain uncertainties. It can be viewed as an extension of the work in Corless and Leitmann [IEEE Trans. Aurom. Conrrol, AC-Xi, 1139-1144 (1981)] for the cases where the vector of uncertainties is only partially known. To cope with the uncertainties, an adaptive controller using a dead-zone and a hysteresis function is proposed, and both the uniform boundedness of all the closed-loop signals and uniform ultimate boundedness of the system state are guaranteed. In contrast with some previous attempts to relax the a priori knowledge on the uncertainties bounds by using a discontinuous control law, we propose continuous control laws in this paper. Hence, chattering problems (which have practical importance) can be avoided.
It is known that rigid body models with two controls cannot be locally asymptotically stabilized ... more It is known that rigid body models with two controls cannot be locally asymptotically stabilized by continuous feedbacks which are functions of the state only. This impossibility does no longer hold when the feedback is also a function of time, or when it is discontinuous. A locally stabilizing smooth time-varying feedback is here explicitly derived by using Center Manifold Theory combined with averaging and Lyapunov techniques.
2018 IEEE Conference on Control Technology and Applications (CCTA), 2018
This paper addresses the problems of estimating the position of an object moving in $n(\geq\ 2)$ ... more This paper addresses the problems of estimating the position of an object moving in $n(\geq\ 2)$ -dimensional Euclidean space using possibly biased velocity measurements and possibly biased range measurements of one or multiple source points. The proposed solutions exploit the Continuous Riccati Equation (CRE) to calculate observer gains yielding global uniform exponential stability of zero estimation errors. These results are obtained under persistent excitation (p.e.) conditions whose satisfaction i) depends on the number and relative positioning of source points and on the object motion properties, and ii) ensures uniform observability and good conditioning of the CRE solutions. In particular, these conditions can be satisfied in the case of a single source point and a moving object. Simulation results illustrate the performance of the proposed observers in this latter case.
2018 IEEE International Conference on Robotics and Automation (ICRA), 2018
This paper revisits the problem of estimating the attitude, linear velocity and depth of an IMU-C... more This paper revisits the problem of estimating the attitude, linear velocity and depth of an IMU-Camera with respect to a planar target. The considered solution relies on the measurement of the optical flow (extracted from the continuous homography) complemented with gyrometer and accelerometer measurements. The proposed deterministic observer is accompanied with an observability analysis that points out camera's motion excitation conditions whose satisfaction grants stability of the observer and convergence of the estimation errors to zero. The performance of the observer is illustrated by performing experiments on a test-bed IMU-Camera system.
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Papers by Claude Samson