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## Publications

Publications (286)

Cuspidal robots can travel from one inverse kinematic solution (IKS) to another without meeting a singularity. This property can be analyzed by understanding the inverse kinematic model (IKM) as well as the singularities in the joint space and in the workspace. In this article, we revisit the geometrical interpretation of the IKM with conics. The c...

Cuspidal robots are robots with at least two inverse kinematic solutions that can be connected by a singularity-free path. Deciding the cuspidality of a generic 3R robots has been studied in the past, but extending the study to six-degree-of-freedom robots can be a challenging problem. Many robots can be modeled as a polynomial map together with a...

Cuspidal robots can travel from one inverse kinematic solution to another without meeting a singularity. The name cuspidal was coined based on the existence of a cusp point in the workspace of 3R serial robots. The existence of a cusp point was proved to be a necessary and sufficient condition for orthogonal robots to be cuspidal, but it was not po...

Cuspidal robots can travel from one inverse kinematic solution to another without meeting a singularity. The name cuspidal was coined based on the existence of a cusp point in the workspace of 3R serial robots. The existence of a cusp point was proved to be a necessary and sufficient condition for orthogonal robots to be cuspidal, but it was not po...

Estimating the motion between two bones is crucial for understanding their biomechanical function. The vertebral column is particularly challenging because the vertebrae articulate at more than one surface. This paper proposes a method to estimate 3D motion between two avian vertebrae, by bones surface reconstruction and contact modeling. The neck...

The vertebrate skeleton is composed of articulated bones. Most of the articulations are classically described using mechanical joints, except the intervertebral joint. The aim of this study was to identify a joint model with the same mechanical features as the cervical joints. On the neck vertebrae, six articular surfaces participate in the joint:...

This paper is devoted to the control and identification of a manipulator with three anti-parallelogram joints in series, referred to as X-joints. Each X-joint is a tensegrity one-degree-of-freedom mechanism antagonistically actuated with cables and springs in parallel. As compared to manipulators built with simple revolute joints in series, manipul...

This paper proposes design strategies and a comparative study of two antagonistically actuated tensegrity joints: a revolute (R) joint and an anti-parallelogram (X) joint. Geometrically, the R-joint has a fixed center of rotation while the X-joint has a moving center of rotation. Both joints are equipped with two lateral springs and are actuated by...

Implementing efficient actuators with good backdriveability properties is of primary importance for the design of high-performance performance bipedal robots. Nowadays, the use of linear direct drive electric motors is an interesting choice. This actuation scheme is closer to the efficient muscular system of human legs. However, the efficiency of l...

Industrial robotic manipulators mostly use revolute or prismatic joints. In this paper, an anti-parallelogram mechanism, referred to as X-joint, is considered as an alternative choice to a revolute joint in the kinematic design of robots. This choice lends itself well to a remote actuation with cables, which contributes to lower inertia. We show th...

This paper compares the static performances of two types of antagonistically actuated joints: a revolute (R) joint and an antiparallelogram (X) joint. Both joints are equipped with lateral springs and actuated with two opposite cables running through the springs. The comparative study is conducted on the basis of their wrench-feasible workspace and...

We present the SIROPA Maple Library which has been designed to study serial and parallel manipulators at the conception level. We show how modern algorithms in Computer Algebra can be used to study the workspace, the joint space but also the existence of some physical capabilities w.r.t. to some design parameters left as degree of freedom for the d...

Piping inspection robots are of greater interests in industries such as nuclear, chemical and sewage. The design of such robots is highly challenging owing to factors such as locomotion inside pipes with varying diameters, cable management, and complex pipe bends (or) junctions. A rigid bio-inspired caterpillar type piping inspection robot was deve...

Piping inspection robots are of greater interests in industries such as nuclear, chemical and sewage. The design of such robots is highly challenging owing to factors such as locomotion inside pipes with varying diameters, cable management, and complex pipe bends (or) junctions. A rigid bio-inspired caterpillar type piping inspection robot was deve...

Piping inspection robots are of greater interests in industries such as nuclear, chemical and sewage. The design of such robots is highly challenging owing to factors such as locomotion inside pipes with varying diameters, cable management, and complex pipe bends (or) junctions. A rigid bio-inspired caterpillar type piping inspection robot was deve...

A planar tensegrity manipulator made of two X-mechanisms in series is studied in this paper. Contrary to a classical 2-R linkage, the proposed architecture does not contain elements subject to bending and it can be driven with remote actuation and cables in an antagonistic way. Accordingly, it is an interesting candidate for the design of lightweig...

A lower-mobility parallel manipulator with multiple operation modes can be considered as inherently reconfigurable. This is the case for 4-RUU parallel manipulators that have three different operation modes. Allowing the first revolute joint axis to have any horizontal orientation leads to a dual reconfigurable 4-rRUU mechanism. This paper presents...

This paper studies a tensegrity manipulator mimicking a bird neck. This manipulator is built upon assembling several X-shape one-dof tensegrity mechanisms in series. A methodology is proposed to derive the dynamic model using Lagrange’s equations. The dynamic model is used to design a dynamic control law. This control law is applied to a backward-a...

This paper presents a preliminary survey of the use of direct drive linear motors for joint actuation of a humanoid robot. Their prime asset relies on backdrivability, a significant feature to properly cushion high impacts between feet and ground during dynamic walking or running. Our long-term goal is the design of high performance human size bipe...

This paper presents a preliminary survey of the use of direct drive linear motors for joint actuation of a humanoid robot. Their prime asset relies on backdrivability, a significant feature to properly cushion high impacts between feet and ground during dynamic walking or running. Our long-term goal is the design of high performance human size bipe...

Constraint equations of a parallel manipulator can be used to analyze their kinematic behaviour. This paper deals with the determination of the algebraic constraint equations of a 3-RUU parallel manipulator with two approaches. The first one is based on the manipulator geometry and the second one uses the Linear Implicitization Algorithm. The obtai...

This paper deals with the optimal design of an antagonistically actuated X-shape Snelson tensegrity mechanism to be used in a preliminary bird neck model made of a series of cascaded such mechanisms. The mechanism, subject to its own weight and to the weight of the subsequent mechanisms, is designed to maximize its wrench feasible workspace under g...

This paper analyzes the workspace of a planar 2-X manipulator, i.e. made of two crossed four-bar mechanisms in series. This architecture has some advantages over classical 2-R manipulators such as its ability to be driven with tendons, but its kinematics is more challenging because of a variable instantaneous center of rotation of the X-mechanisms....

This chapter is dedicated to the so-called cuspidal robots; i.e., those robots that can move from one inverse geometric solution to another without meeting a singular configuration. This feature was discovered quite recently and has then been fascinating a lot of researchers. After a brief history of cuspidal robots, the chapter provides the main f...

This PhD is part of the AVINECK project which involves biologists and roboticists guided by the following assumption : "The bird neck, an arm for the robot". The project aims at : • having a better understanding of musculo-skelettal systems in bird necks. • Designing an efficient and innovative robotic arm inspired from nature. Tensegrity structure...

This paper deals with the kinematic analysis and enumeration of singularities of the six degree-of-freedom 3-RPS-3-SPR series–parallel manipulator (S–PM). The characteristic tetrahedron of the S–PM is established, whose degeneracy is bijectively mapped to the serial singularities of the S–PM. Study parametrization is used to determine six independe...

Tensegrity mechanisms are composed of rigid and tensile parts that are in equilibrium. They are interesting alternative designs for some applications, such as modeling musculo-skeleton systems. Tensegrity mechanisms are more difficult to analyze than classical mechanisms as the static equilibrium conditions that must be satisfied generally result i...

Tensegrity mechanisms have several interesting properties that make them suitable for a number of applications. Their analysis is generally challenging because the static equilibrium conditions often result in complex equations. A class of planar one-degree-of-freedom (dof) tensegrity mechanisms with three linear springs is analyzed in detail in th...

This paper aims to shed light on the determination of the true mobility for a 3-RPS-3-SPR series-parallel manipulator, which was claimed to be six in [6] without any proof, and shown to be five in [3, 4] with an erroneous proof. Screw theory is used to derive the kinematic Jacobian matrix and the twist system of the mechanism, leading to the determ...

This paper addresses the dimensional synthesis and design optimization of a three-degree-of-freedom planar U-shape fixed base 2PRP-PRR parallel manipulator to maximize its workspace. Two kinematic design solutions are proposed and their link parameters are optimized to maximize the workspace. Furthermore, accuracy analysis of the optimized manipula...

This paper analyzes the kinematics of planar tensegrity manipulators made of two Snelson’s X-shape mechanisms in series. The variable instantaneous center of rotation of each mechanism renders the kinematic analysis of the resulting manipulator more challenging. A general formulation of the direct kinematics is set. A method is proposed to solve th...

This paper analyses the dynamics of an antagonistically actuated tensegrity mechanism. The mechanism is subject to gravity effects, which produce both stable and unstable equilibrium configurations. The workspace is shown to be not necessarily connected and its size depends on both the geometric, spring and actuator parameters of the mechanism. The...

This paper investigates a situation pointed out in a recent paper, in which a non-singular change of assembly mode of a planar 2-RPR-PR parallel manipulator was realized by encircling a point of multiplicity 4. It is shown that this situation is, in fact, a non-generic one and gives rise to cusps under a small perturbation. Furthermore, we show tha...

Tensegrity mechanisms have several interesting properties that make them suitable for a number of applications. Their analysis is generally challenging because the static equilibrium conditions often result in complex equations. A class of planar one-degree-of-freedom (dof) tensegrity mechanisms with three linear springs is analyzed in detail in th...

This paper deals with the comparison of 3-RPS and 3-SPR parallel manipulators based on their operation modes and singularity-free workspace. The operation modes of the 3-SPR manipulator are identified by using algebraic geometry. Those operation modes amount to the operation modes of the 3-RPS parallel manipulator, which has already been studied in...

This chapter is dedicated to the so-called cuspidal robots, i.e. those robots that can move from one inverse geometric solution to another without meeting a singular confuguration. This feature was discovered quite recently and has then been fascinating a lot of researchers. After a brief history of cuspidal robots, the chapter provides the main fe...

This paper investigates a situation pointed out in a recent paper, in which a non-singular change of assembly mode of a planar 2-RPR-PR parallel manipulator was realized by encircling a point of multiplicity 4. It is shown that this situation is, in fact, a non-generic one and gives rise to cusps under a small perturbation. Furthermore , we show th...

A method for joint trajectory planning of kinematically redundant parallel manipulators is presented in this paper. The method is based on the use of feasibility maps that allow the graphical assessment of postures related to the different working modes of the manipulator. Thus, in such maps suitable trajectories are found in order to improve the p...

The design of new manipulators requires the knowledge of their kinematic
behaviour. Important kinematic properties can be characterized by the
determination of certain points of interest. Important points of interest are
cusps and nodes, which are special singular points responsible for the
non-singular posture changing ability and for the existenc...

Medical and service robotics integrates several disciplines and technologies such as mechanisms, mechatronics, biomechanics, humanoid robotics, exoskeletons, and anthropomorphic hands.
This book presents the most recent advances in medical and service robotics, with a stress on human aspects. It collects the selected peer-reviewed papers of the Fou...

This paper presents some analytical results related to the determination of the singular poses of the 3-RPS parallel manipulator at which it gains two degrees of freedom. The forward kinematic univariate (FKU) of the manipulator acquires a special structure at such a pose. All such poses have been identified in the closed-form, using a Stüdy-parame...

This paper deals with the characterization of the operation modes of the 4-RUU parallel manipulator with an algebraic approach, namely the Study's kinematic mapping of the Euclidean group SE(3). As the 4-RUU parallel manipulator is an over-constrained manipulator, it can be decomposed into two 2-RUU parallel manipulators. The manipulators are descr...

p>The design of new manipulators requires the knowledge of their kinematic behaviour. Important kinematic properties can be characterized by the determination of certain points of interest. Important points of interest are cusps and nodes, which are special singular points responsible for the non-singular posture changing ability and for the existe...

The subject of this paper is about the study of the operation modes and the singularity conditions of the 3-PRS parallel manipulator with different arrangements of prismatic joints. The three prismatic joints of the PRS legs are attached to the base with an angle α between the horizontal plane of the base and their directions.
By using an algebraic...