R. Bearee - Academia.edu (original) (raw)

Papers by R. Bearee

IFAC-PapersOnLine, 2017

In this work, redundancy resolution has been employed to increase the Cartesian mechanical rigidi... more In this work, redundancy resolution has been employed to increase the Cartesian mechanical rigidity of 7 DOF robot manipulators during tasks requiring stiff interactions with the environment (e.g. milling or drilling). The Cartesian static stiffness of the end-effector for a given joint configuration is deduced from an identified joints stiffness model. The Cartesian reflected rigidity evolution over an analytically computed self-motion of the manipulator shows significant variations that clearly highlight the need to select the right set of joint angles among the possible ones. A global optimization scheme of the redundant DOF is proposed to determine the stiffest robot configurations for a given pose of the end-effector. An experimental study on 7 DOF KUKA LBR iiwa then shows the relevance of the proposed approach in finding the redundant robot joint angles that optimize this rigidity criteria.

IECON 2006 - 32nd Annual Conference on IEEE Industrial Electronics, 2006

ABSTRACT This paper addresses the problem control synthesis for a class of electromechanical syst... more ABSTRACT This paper addresses the problem control synthesis for a class of electromechanical systems, which can be accurately decomposed into lumped parameters. The control design methodology using the causal ordering graph is based on a "natural" representation of the process and on two complementary inversion principles leading to a state control structure. This paper generalizes the concept of inversion and proposes a systematic method of control synthesis, starting from a model based on the concept of localized energies and described by the COG. We demonstrate that some control solutions, conventional or particular, can be determined. Experimental results confirm the validity of the suggested methodology

This paper addresses the problem of modelling and control synthesis for a class of electromechani... more This paper addresses the problem of modelling and control synthesis for a class of electromechanical systems, which can be accurately decomposed into lumped constant parameters. The control design methodology presented in our former publications is based on a "natural" representation of the process and on two complementary inversion principles leading to a state control structure. This paper generalizes the concept of inversion and proposes a systematic method of control synthesis for the electromechanical processes, starting from a model based on the concept of localized energies and described by the Causal Ordering Graph (COG). We demonstrate that some control solutions, conventional or particular, can be expressed theoretically. The main interest is the systematic deductive aspect of the methodology, aiming at a faithful copy of the desired trajectories.

2013 15th European Conference on Power Electronics and Applications (EPE), 2013

This paper presents a new powder transportation system that uses a high frequency flexural statio... more This paper presents a new powder transportation system that uses a high frequency flexural stationary wave coupled with a low frequency horizontal displacement of a beam to produce the transport of the powder. The ultrasonic wave is produced with the help of piezoelectric cells glued under the beam and is used to decrease the friction coefficient between the powder and the beam surface.

In this article, we justify the use of parametric planar Pythagorean Hodograph spline curves in p... more In this article, we justify the use of parametric planar Pythagorean Hodograph spline curves in path planning. The elegant properties of such splines enable us to design an efficient interpolator algorithm, more precise than the classical Taylor interpolators and faster than an interpolator based on arc length computations.

The use of industrial robots in many fields of industry like prototyping, pre-machining and end m... more The use of industrial robots in many fields of industry like prototyping, pre-machining and end milling is limited because of their poor accuracy. Robot joints are mainly responsible for this poor accuracy. The flexibility of robots joints and the kinematic errors in the transmission systems produce a significant error of position in the level of the end-effector. This paper presents these two types of joint errors. Identification methods are presented with experimental validation on a 6 axes industrial robot, STAUBLI RX 170 BH. An offline correction method used to improve the accuracy of this robot is validated experimentally.

This paper is concerned with preliminary results on robot vibratory modes on-line estimation. The... more This paper is concerned with preliminary results on robot vibratory modes on-line estimation. The dominating oscillatory mode of the robot arm is isolated by comparing the robot position given by the motors encoders and an external measure at the tool-tip of the robot arm. In this article the external measurement is provided by a laser tracker. The isolation of the oscillation permits to identify the vibratory mode, i.e. the natural frequency and the damping ratio of the undesired phenomena. Here we propose a comparison between the algebraic method and the sliding modes for the parameter identification. This comparison is motivated by the fact that both methods provide finite time convergence. Experimental identifications are proposed on a 6 degrees of freedom (DOF) manipulator robot, Stäubli RX-170B.

Résumé: This article address the identification problem of the natural frequency and the damping ... more Résumé: This article address the identification problem of the natural frequency and the damping ratio of a second order continuous system where the input is a sinusoidal signal. An algebra based approach for identifying parameters of a Mass Spring Damper (MSD) ...

Control Engineering Practice, 2010

Nowadays, the adaptation of industrial robots to carry out high-speed machining operations is str... more Nowadays, the adaptation of industrial robots to carry out high-speed machining operations is strongly required by the manufacturing industry. This new technology machining process demands the improvement of the overall performances of robots to achieve an accuracy level close to that realized by machine-tools. This paper presents a method of trajectory planning adapted for continuous machining by robot. The methodology used is based on a parametric interpolation of the geometry in the operational space. FIR filters properties are exploited to generate the tool feedrate with limited jerk. This planning method is validated experimentally on an industrial robot.

ABSTRACT In this article, we justify the use of parametric planar Pythagorean Hodograph spline cu... more ABSTRACT In this article, we justify the use of parametric planar Pythagorean Hodograph spline curves in path planning. The elegant properties of such splines enable us to design an efficient interpolator algorithm, more precise than the classical Taylor interpolators and faster than an interpolator based on arc length computations.

ABSTRACT Afin d’accroître leur compétitivité les entreprises ont recours de plus en plus à des sy... more ABSTRACT Afin d’accroître leur compétitivité les entreprises ont recours de plus en plus à des systèmes robotisés pour realiser différentes tâches complexes. Ces robots sont très attractifs par leur coût mais nécessitent d’introduire des capteurs externes afin de garantir une plus grande précision de mouvement. Un enjeu majeur concerne la co-activité avec l’homme. Fort de l’acquisition très récente du système de vision low-cost, Leap Motion, qui présente des caractéristiques de précision inégalées à ce coût, nous proposons un premier travail d’apprentissage, par un système robotisé, de la gestuelle d’un opérateur. L’objectif est de reproduire des tâches complexes en 3D sans contraintes pour l’opérateur. Cette interaction permet d’engendrer un nuage de points et de directions très précises. Afin de garantir une bonne répétabilité du mouvement sur notre robot UR10, nous réalisons une interpolation de ces données par des splines polynomiales minimisant la norme L1. Ce formalisme développé récemment présente une complexité de calcul linéaire avec les données et permet de conserver la forme des données même lorsque le pas de discrétisation n’est pas uniforme en espace.

Journal Européen des Systèmes Automatisés, 2004

ABSTRACT This paper deals with the specific influence of the jerk value on the behaviour of indus... more ABSTRACT This paper deals with the specific influence of the jerk value on the behaviour of industrial high-speed systems. The physical relationships between the jerk maximum value, the vibratory level reached and the effective movement time are formalised on a axis-drive model taking account of the main control parameters and effects of a predominating deformation mode. Experimental tests conducted on three test-setups with different architectures and characteristics demonstrate the effectiveness of the suggested approach in estimating the evolution of the maximum residual oscillations.

2010 IEEE Vehicle Power and Propulsion Conference, 2010

ABSTRACT In this paper, a trajectory generator based on causal modeling is presented. This strate... more ABSTRACT In this paper, a trajectory generator based on causal modeling is presented. This strategy is applied to the velocity constraint trajectory generation of an automatic subway. The constraints take into account of passengers comfort by the use of imposed maximum jerk and acceleration values. The proposed velocity generator is enhanced by the use of torque model of the DC machines. The proposed velocity planning method is applied to a model of the VAL subway and comparisons with the present control structure are provided.

Proceedings of the 16th IFAC World Congress, 2005, 2005

Vibration-free positioning is a basic objective in industrial high-speed systems, i.e. systems fo... more Vibration-free positioning is a basic objective in industrial high-speed systems, i.e. systems for which axes are submitted to significant dynamical demands. The focus of this paper is on the pragmatic formalisation of the influence of some jerk-controlled movement laws on the residual vibrations. Analysis of limited-jerk, harmonic-jerk and minimum-jerk laws is conducted on a simplified axis drive model that accounts for axis control parameters and for predominant mode effects. Experimental measurements performed on industrial test-setups demonstrate the effectiveness of the proposed approach in estimating the evolution of the vibration level according to each movement law. A c c e l e r a t i o n V e l o c i t y V m A m J J e r k T a T v P o s i t i o n T L A + T j t A c c e l e r a t i o n V e l o c i t y V m A m P o s i t i o n T L A = > t A c c e l e r a t i o n V e l o c i t y J e r k P o s i t i o n T M J V m J A m t A c c e l e r a t i o n V e l o c i t y J e r k P o s i t i o n V m J A m ? @ T L A + T j

ABSTRACT Afin d’accroître leur compétitivité les entreprises ont recours de plus en plus à des sy... more ABSTRACT Afin d’accroître leur compétitivité les entreprises ont recours de plus en plus à des systèmes robotisés pour realiser différentes tâches complexes. Ces robots sont très attractifs par leur coût mais nécessitent d’introduire des capteurs externes afin de garantir une plus grande précision de mouvement. Un enjeu majeur concerne la co-activité avec l’homme. Fort de l’acquisition très récente du système de vision low-cost, Leap Motion, qui présente des caractéristiques de précision inégalées à ce coût, nous proposons un premier travail d’apprentissage, par un système robotisé, de la gestuelle d’un opérateur. L’objectif est de reproduire des tâches complexes en 3D sans contraintes pour l’opérateur. Cette interaction permet d’engendrer un nuage de points et de directions très précises. Afin de garantir une bonne répétabilité du mouvement sur notre robot UR10, nous réalisons une interpolation de ces données par des splines polynomiales minimisant la norme L1. Ce formalisme développé récemment présente une complexité de calcul linéaire avec les données et permet de conserver la forme des données même lorsque le pas de discrétisation n’est pas uniforme en espace.

IFAC-PapersOnLine, 2017

In this work, redundancy resolution has been employed to increase the Cartesian mechanical rigidi... more In this work, redundancy resolution has been employed to increase the Cartesian mechanical rigidity of 7 DOF robot manipulators during tasks requiring stiff interactions with the environment (e.g. milling or drilling). The Cartesian static stiffness of the end-effector for a given joint configuration is deduced from an identified joints stiffness model. The Cartesian reflected rigidity evolution over an analytically computed self-motion of the manipulator shows significant variations that clearly highlight the need to select the right set of joint angles among the possible ones. A global optimization scheme of the redundant DOF is proposed to determine the stiffest robot configurations for a given pose of the end-effector. An experimental study on 7 DOF KUKA LBR iiwa then shows the relevance of the proposed approach in finding the redundant robot joint angles that optimize this rigidity criteria.

IECON 2006 - 32nd Annual Conference on IEEE Industrial Electronics, 2006

ABSTRACT This paper addresses the problem control synthesis for a class of electromechanical syst... more ABSTRACT This paper addresses the problem control synthesis for a class of electromechanical systems, which can be accurately decomposed into lumped parameters. The control design methodology using the causal ordering graph is based on a "natural" representation of the process and on two complementary inversion principles leading to a state control structure. This paper generalizes the concept of inversion and proposes a systematic method of control synthesis, starting from a model based on the concept of localized energies and described by the COG. We demonstrate that some control solutions, conventional or particular, can be determined. Experimental results confirm the validity of the suggested methodology

This paper addresses the problem of modelling and control synthesis for a class of electromechani... more This paper addresses the problem of modelling and control synthesis for a class of electromechanical systems, which can be accurately decomposed into lumped constant parameters. The control design methodology presented in our former publications is based on a "natural" representation of the process and on two complementary inversion principles leading to a state control structure. This paper generalizes the concept of inversion and proposes a systematic method of control synthesis for the electromechanical processes, starting from a model based on the concept of localized energies and described by the Causal Ordering Graph (COG). We demonstrate that some control solutions, conventional or particular, can be expressed theoretically. The main interest is the systematic deductive aspect of the methodology, aiming at a faithful copy of the desired trajectories.

2013 15th European Conference on Power Electronics and Applications (EPE), 2013

This paper presents a new powder transportation system that uses a high frequency flexural statio... more This paper presents a new powder transportation system that uses a high frequency flexural stationary wave coupled with a low frequency horizontal displacement of a beam to produce the transport of the powder. The ultrasonic wave is produced with the help of piezoelectric cells glued under the beam and is used to decrease the friction coefficient between the powder and the beam surface.

In this article, we justify the use of parametric planar Pythagorean Hodograph spline curves in p... more In this article, we justify the use of parametric planar Pythagorean Hodograph spline curves in path planning. The elegant properties of such splines enable us to design an efficient interpolator algorithm, more precise than the classical Taylor interpolators and faster than an interpolator based on arc length computations.

The use of industrial robots in many fields of industry like prototyping, pre-machining and end m... more The use of industrial robots in many fields of industry like prototyping, pre-machining and end milling is limited because of their poor accuracy. Robot joints are mainly responsible for this poor accuracy. The flexibility of robots joints and the kinematic errors in the transmission systems produce a significant error of position in the level of the end-effector. This paper presents these two types of joint errors. Identification methods are presented with experimental validation on a 6 axes industrial robot, STAUBLI RX 170 BH. An offline correction method used to improve the accuracy of this robot is validated experimentally.

This paper is concerned with preliminary results on robot vibratory modes on-line estimation. The... more This paper is concerned with preliminary results on robot vibratory modes on-line estimation. The dominating oscillatory mode of the robot arm is isolated by comparing the robot position given by the motors encoders and an external measure at the tool-tip of the robot arm. In this article the external measurement is provided by a laser tracker. The isolation of the oscillation permits to identify the vibratory mode, i.e. the natural frequency and the damping ratio of the undesired phenomena. Here we propose a comparison between the algebraic method and the sliding modes for the parameter identification. This comparison is motivated by the fact that both methods provide finite time convergence. Experimental identifications are proposed on a 6 degrees of freedom (DOF) manipulator robot, Stäubli RX-170B.

Résumé: This article address the identification problem of the natural frequency and the damping ... more Résumé: This article address the identification problem of the natural frequency and the damping ratio of a second order continuous system where the input is a sinusoidal signal. An algebra based approach for identifying parameters of a Mass Spring Damper (MSD) ...

Control Engineering Practice, 2010

Nowadays, the adaptation of industrial robots to carry out high-speed machining operations is str... more Nowadays, the adaptation of industrial robots to carry out high-speed machining operations is strongly required by the manufacturing industry. This new technology machining process demands the improvement of the overall performances of robots to achieve an accuracy level close to that realized by machine-tools. This paper presents a method of trajectory planning adapted for continuous machining by robot. The methodology used is based on a parametric interpolation of the geometry in the operational space. FIR filters properties are exploited to generate the tool feedrate with limited jerk. This planning method is validated experimentally on an industrial robot.

ABSTRACT In this article, we justify the use of parametric planar Pythagorean Hodograph spline cu... more ABSTRACT In this article, we justify the use of parametric planar Pythagorean Hodograph spline curves in path planning. The elegant properties of such splines enable us to design an efficient interpolator algorithm, more precise than the classical Taylor interpolators and faster than an interpolator based on arc length computations.

ABSTRACT Afin d’accroître leur compétitivité les entreprises ont recours de plus en plus à des sy... more ABSTRACT Afin d’accroître leur compétitivité les entreprises ont recours de plus en plus à des systèmes robotisés pour realiser différentes tâches complexes. Ces robots sont très attractifs par leur coût mais nécessitent d’introduire des capteurs externes afin de garantir une plus grande précision de mouvement. Un enjeu majeur concerne la co-activité avec l’homme. Fort de l’acquisition très récente du système de vision low-cost, Leap Motion, qui présente des caractéristiques de précision inégalées à ce coût, nous proposons un premier travail d’apprentissage, par un système robotisé, de la gestuelle d’un opérateur. L’objectif est de reproduire des tâches complexes en 3D sans contraintes pour l’opérateur. Cette interaction permet d’engendrer un nuage de points et de directions très précises. Afin de garantir une bonne répétabilité du mouvement sur notre robot UR10, nous réalisons une interpolation de ces données par des splines polynomiales minimisant la norme L1. Ce formalisme développé récemment présente une complexité de calcul linéaire avec les données et permet de conserver la forme des données même lorsque le pas de discrétisation n’est pas uniforme en espace.

Journal Européen des Systèmes Automatisés, 2004

ABSTRACT This paper deals with the specific influence of the jerk value on the behaviour of indus... more ABSTRACT This paper deals with the specific influence of the jerk value on the behaviour of industrial high-speed systems. The physical relationships between the jerk maximum value, the vibratory level reached and the effective movement time are formalised on a axis-drive model taking account of the main control parameters and effects of a predominating deformation mode. Experimental tests conducted on three test-setups with different architectures and characteristics demonstrate the effectiveness of the suggested approach in estimating the evolution of the maximum residual oscillations.

2010 IEEE Vehicle Power and Propulsion Conference, 2010

ABSTRACT In this paper, a trajectory generator based on causal modeling is presented. This strate... more ABSTRACT In this paper, a trajectory generator based on causal modeling is presented. This strategy is applied to the velocity constraint trajectory generation of an automatic subway. The constraints take into account of passengers comfort by the use of imposed maximum jerk and acceleration values. The proposed velocity generator is enhanced by the use of torque model of the DC machines. The proposed velocity planning method is applied to a model of the VAL subway and comparisons with the present control structure are provided.

Proceedings of the 16th IFAC World Congress, 2005, 2005

Vibration-free positioning is a basic objective in industrial high-speed systems, i.e. systems fo... more Vibration-free positioning is a basic objective in industrial high-speed systems, i.e. systems for which axes are submitted to significant dynamical demands. The focus of this paper is on the pragmatic formalisation of the influence of some jerk-controlled movement laws on the residual vibrations. Analysis of limited-jerk, harmonic-jerk and minimum-jerk laws is conducted on a simplified axis drive model that accounts for axis control parameters and for predominant mode effects. Experimental measurements performed on industrial test-setups demonstrate the effectiveness of the proposed approach in estimating the evolution of the vibration level according to each movement law. A c c e l e r a t i o n V e l o c i t y V m A m J J e r k T a T v P o s i t i o n T L A + T j t A c c e l e r a t i o n V e l o c i t y V m A m P o s i t i o n T L A = > t A c c e l e r a t i o n V e l o c i t y J e r k P o s i t i o n T M J V m J A m t A c c e l e r a t i o n V e l o c i t y J e r k P o s i t i o n V m J A m ? @ T L A + T j

ABSTRACT Afin d’accroître leur compétitivité les entreprises ont recours de plus en plus à des sy... more ABSTRACT Afin d’accroître leur compétitivité les entreprises ont recours de plus en plus à des systèmes robotisés pour realiser différentes tâches complexes. Ces robots sont très attractifs par leur coût mais nécessitent d’introduire des capteurs externes afin de garantir une plus grande précision de mouvement. Un enjeu majeur concerne la co-activité avec l’homme. Fort de l’acquisition très récente du système de vision low-cost, Leap Motion, qui présente des caractéristiques de précision inégalées à ce coût, nous proposons un premier travail d’apprentissage, par un système robotisé, de la gestuelle d’un opérateur. L’objectif est de reproduire des tâches complexes en 3D sans contraintes pour l’opérateur. Cette interaction permet d’engendrer un nuage de points et de directions très précises. Afin de garantir une bonne répétabilité du mouvement sur notre robot UR10, nous réalisons une interpolation de ces données par des splines polynomiales minimisant la norme L1. Ce formalisme développé récemment présente une complexité de calcul linéaire avec les données et permet de conserver la forme des données même lorsque le pas de discrétisation n’est pas uniforme en espace.