Browsing by Author "Krut, Sébastien"
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Item An agile manufacturing system for large workspace applications(Springer Verlag, 2013) Yang, Hai; Baradat, Cédric; Krut, Sébastien; Pierrot, François; MEDIOS DE PRODUCCIÓN Y ROBOTICA; Tecnalia Research & InnovationREMORA aims at offering an agile robotic solution for manufacturing tasks done on very large parts (e.g.: very long and slender parts found in aeronautic industries). For such tasks, classical machine-tools are designed at several tens of meters. Both their construction and operation require huge infrastructure supports. REMORA is a novel lightweight concept and flexible robotic solution that combines the ability of walking and manufacturing. The robot is a mobile manufacturing system which can effectuate operations with good payload capacity and good precisions for large workspace applications. This new concept combines parallel kinematics to ensure high stiffness but low inertia, and mobile robotics to operate in very large workspaces. This results in a machining center of new generation: 1. Agile manufacturing system for large workspace applications; 2. Heavy load and good precisions; 3. 5-axis machining and 5-axis locomotion/clamping; 4. Self-reconfigurable for specific tasks (workspace and force); 5. Flexible and multifunctional (machining, fixture).Item An agile manufacturing system for large workspace applications(2016-07-01) Yang, Hai; Baradat, Cédric; Krut, Sébastien; Pierrot, François; MEDIOS DE PRODUCCIÓN Y ROBOTICA; Tecnalia Research & InnovationREMORA aims at offering an agile robotic solution for manufacturing tasks done on very large parts (e.g., very long and slender parts found in aeronautic industries). For such tasks, classical machine tools are designed at several tens of meters. Both their construction and operation require huge infrastructure supports. REMORA is a novel lightweight concept and flexible robotic solution that combines the ability of walking and manufacturing. The robot is a mobile manufacturing system which can effectuate operations with good payload capacity and good precisions for large workspace applications. This new concept combines parallel kinematics to ensure high stiffness but low inertia and mobile robotics to operate in very large workspaces. This results in a machining center of new generation: (1) agile manufacturing system for large workspace applications, (2) heavy load and good precisions, (3) 5-axis machining and 5-axis locomotion/clamping, (4) self-reconfigurable for specific tasks (workspace and force), and (5) flexible and multifunctional.Item Effects of non-negligible cable mass on the static behavior of large workspace cable-driven parallel mechanisms(2009) Riehl, Nicolas; Gouttefarde, Marc; Krut, Sébastien; Baradat, Cédric; Pierrot, François; Tecnalia Research & InnovationCable-driven robots are currently extensively studied. Generally, for this type of manipulators, cables are considered to be massless and inextensible. But for large working volume applications, their mass cannot be neglected. Based on a well-known model which describes the profile of a cable under the action of its own weight, the inverse and forward kinematics of minimally constrained cable-driven manipulators can be numerically computed. This paper studies the effects of taking cable mass into account by comparison to classical massless cable model. It highlights the real effects of such a model on cable lengths to reach a given position. The effects on cable tensions are also studied.Item Heli4: A parallel robot for scara motions with a very compact traveling plate and a symmetrical design(2006) Krut, Sébastien; Company, Olivier; Nabat, Vincent; Pierrot, François; Tecnalia Research & InnovationThis paper introduces Heli4 a new 4 degree-of-freedom parallel robot. It is inspired by the Delta architecture, but was designed to overcome its limitations, using an articulated traveling plate. Unlike most articulated traveling plates, Heli4's traveling plate is very compact. Among other positive aspects is its symmetrical design. This paper gives the geometrical models, and particularly the forward position relationship which can be obtained in a closed form. In a third part, a detailed study of the robot singularities is made by taking into account the not-so-classic internal singularities.Item A high-speed parallel robot for scara motions(2004) Krut, Sébastien; Nabat, Vincent; Company, Olivier; Pierrot, François; Tecnalia Research & InnovationThis paper introduces a new 4 degree-of-freedom parallel robot. It presents its architecture inspired by FlexPicker, an ABB machine based on the Delta architecture, while overcoming its drawbacks. This paper exposes the way to get the geometrical models, and particularly the forward position relationship which can be obtained in a closed form. In a third part, a detailed study of the robot singularities is made by taking into account the not-so-classic internal singularities. Design conditions are obtained for isostatic and over-constrained cases. The robot optimization and its workspace are finally presented.Item Locomotion approach of REMORA: A reonfigurable mobile robot for manufacturing Applications(2011) Yang, Hai; Krut, Sébastien; Baradat, Cédric; Pierrot, François; MEDIOS DE PRODUCCIÓN Y ROBOTICA; Tecnalia Research & InnovationThis paper presents the locomotion approach of a novel quadruped robot which is able to carry various effectors for achieving manufacturing tasks in large workspaces. Equipped with lockers on some of the passive joints and clamping devices at the end of its limbs, this quadruped uses eight actuators for achieving manufacturing tasks as well as locomotion tasks. In the following sections, we first present the proposed robot and its two working modes. Then, the locking strategy of the robot is formulated as an optimization problem. Also, a practical method for managing the limbs swinging movement is addressed. At last, the presented approach is applied on two concrete examples. Possessing a low degree of kinematic redundancy, the proposed quadruped shows a reasonable locomotion capacity which allows it to achieve locomotion with respect to some extra constrains in its workspaces.Item A new concept of self-reconfigurable mobile machining centers(2010) Yang, Hai; Krut, Sébastien; Baradat, Cédric; Pierrot, François; MEDIOS DE PRODUCCIÓN Y ROBOTICA; Tecnalia Research & InnovationIn this paper, several considerations for designing industry oriented robots which combine the mobility of legged robots and advantages of parallel mechanisms are outlined. A tripod and a quadruped with the same kind of legs are studied. The robots' kinematic models are built for achieving the machining and walking scenarios. The simulations show that: integrating some clamping devices and some lockable passive joints, six actuators are enough to build a legged manipulator which can not only perform 6-axis machining but can also walk on a curved supporting media. Using the "modified condition number" index, the two mechanisms are compared. They have similar workspaces and static wrench performances during the machining phase. During walking processes, however, their behaviors are different, and each of them shows interesting features depending on application requirement.Item A novel 4 DoFs (3T-1R) parallel manipulator with actuation redundancy – Workspace analysis(Kluwer Academic Publishers, 2014) Shayya, Samah; Krut, Sébastien; Company, Olivier; Baradat, Cédric; Pierrot, François; Petuya, Victor; Pinto, Charles; Petuya, Victor; Lovasz, Erwin-Christian; Lovasz, Erwin-Christian; Pinto, Charles; Tecnalia Research & Innovationpaper presents a novel 4 dofs (3T-1R1) parallel actuatedly redundant mechanism and its workspace analysis, based on a performance index involving velocity and force capabilities. The robot is capable of performing a half-turn2 about the z axis. Moreover, having all of its prismatic actuators along one direction; the x motion is independent- only limited by the stroke of the prismatic actuators. The mechanism is characterized by elevated dynamical capabilities having its actuators at base.Item On the design of mobile parallel robots for large workspace applications(2011) Yang, Hai; Krut, Sébastien; Pierrot, François; Baradat, Cédric; MEDIOS DE PRODUCCIÓN Y ROBOTICA; Tecnalia Research & InnovationIn this paper, several considerations for designing industry oriented robots which combine the mobility of legged robots and advantages of parallel mechanisms are outlined. For designing such optimized robots in terms of simplicity and performance, a topology study is done based on the mobility analysis. Applying some design constraints, potential topologies of such robots are identified. One architecture is chosen for designing a tripod robot. Both inverse and forward kinematic problems of this robot are derived in order to simulate its gait motion. The analysis and simulations show that: integrating some clamping devices and some lockable passive joints, six actuators are enough to build a legged manipulator which can not only perform 6-axis machining but can also walk on a curved supporting media.Item On the performance evaluation and analysis of general robots with mixed dofs(Institute of Electrical and Electronics Engineers Inc., 2014-10-31) Shayya, Samah; Krut, Sébastien; Company, Olivier; Baradat, Cédric; Pierrot, François; Tecnalia Research & InnovationThis paper deals with the kinetostatic performance evaluation regarding translational and rotational motions of general robots with mixed operational degrees of freedom (dofs). Also, robots with different types of actuators can be analyzed based on the same approach without any problem. Besides, the generality of the approach embraces serial, parallel, actuatedly or kinematically redundant robots. The paper seeks clarifying the issue and providing a relevant solution. It also clarifies some other useful points in this matter.Item Optimal design of a 4-DOF parallel manipulator: From academia to industry(2009) Pierrot, François; Nabat, Vincent; Company, Olivier; Krut, Sébastien; Poignet, Philippe; Tecnalia Research & InnovationThis paper presents an optimal design of a parallel manipulator aiming to perform pick-and-place operations at high speed and high acceleration. After reviewing existing architectures of high-speed and high-acceleration parallel manipulators, a new design of a 4-DOF parallel manipulator is presented, with an articulated traveling plate, which is free of internal singularities and is able to achieve high performances. The kinematic and simplified, but realistic, dynamic models are derived and validated on a manipulator prototype. Experimental tests show that this design is able to perform beyond the high targets, i.e., it reaches a speed of 5.5 m/s and an acceleration of 165 m/s2. The experimental prototype was further optimized on the basis of kinematic and dynamic criteria. Once the motors, gear ratio, and several link lengths are determined, a modified design of the articulated traveling plate is proposed in order to reach a better dynamic equilibrium among the four legs of the manipulator. The obtained design is the basis of a commercial product offering the shortest cycle times among all robots available in today's market.Item Par2: A spatial mechanism for fast planar two-degree-of-freedom pick-and-place applications(2011-02) Company, Olivier; Pierrot, François; Krut, Sébastien; Baradat, Cédric; Nabat, Vincent; Tecnalia Research & InnovationThis paper introduces a new two-degree-of-freedom (dof) parallel manipulator producing two translations in the vertical plane. One drawback of existing robots built to realize these dof is their lack of transversal stiffness, another one being their limited ability to provide very high acceleration. Indeed, these architectures cannot be lightweight and stiff at the same time. The proposed parallel architecture is a spatial mechanism which guarantees a good transversal stiffness. It is composed by two actuated kinematic chains, and two passive chains built in the transversal plane. The key feature of this robot comes from the two passive chains which are coupled to create a kinematic constraint: the platform stays in one plane. A stiffness analysis shows that the robot can be lighter and stiffer than a classical 2-dof mechanism. A prototype of this robot is presented and preliminary tests show that accelerations above 400 ms-1 can be achieved while keeping a low tracking error.