Browsing by Author "Pierrot, François"
Now showing 1 - 20 of 25
Results Per Page
Sort Options
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 AIR2, un robot parallèle à actionnement pneumatique à deux degrés de liberté pour les applications de prise et dépose d'objets(2011) Chikh, Lotfi; Baradat, Cédric; Poignet, Philippe; Pierrot, François; Michelin, Micaël; Tecnalia Research & InnovationA two degrees-of-freedom pneumatically driven parallel robot has been developed for pick-and-place of payloads comprised between 5 and 20 kg using standard double acting cylinders cheaper than electrical motors. After the general presentation of the robot, the actuator models are developed and a novel control strategy is introduced based on a cascade scheme with a predictive position controller and an inner H∞ force control. Some experimental results are then presented and analyzed in order to show the effectiveness of the controllers.Item Anti-windup design for saturation management during piezo-actuated vibration attenuation of the high-speed parallel robot Par2(IFAC Secretariat, 2013) Douat, Luiz R.; Queinnec, Isabelle; Garcia, Germain; Michelin, Micaël; Pierrot, François; Tarbouriech, Sophie; Tecnalia Research & InnovationThe two degrees of freedom parallel robot Par2 is designed for high-speed and high-accuracy industrial pick-and-place operation tasks. As a result of high acceleration trajectories, its end-effector undergoes some undesirable vibrations after reaching the stop position, compromising precision and leading to an increase in the operation cycle time. Accelerometer sensors placed on the end-effector and piezoelectric patch actuators wrapped around the robot arms are employed in order to actively reduce these vibrations. Without taking into account saturation limitations, a robust controller is designed, minimizing vibrations for the robot nominal operating point but failing for some extreme operating points, due to high control efforts. An anti-windup strategy is then employed to deal with the saturation of the actuator. Such a strategy presents the advantage, with respect to the strategy which would consider a controller with smoother control efforts, to maintain a good level of vibration attenuation on the whole operation domain. Simulations and experimental results attest the adequacy of the proposed solution.Item A combined GPC-H ∞ cascade control for pneumatic actuators: A comparative study(2012) Chikh, Lotfi; Poignet, Philippe; Pierrot, François; Baradat, Cédric; Michelin, Micaël; Tecnalia Research & InnovationThis paper presents a comparison study between three types of pneumatic actuators. The goal is to choose the most suitable for low cost and high power-to-weight pick-and-place parallel robotic tasks. A cascade strategy scheme with an outer predictive position controller and an inner pressure H ∞ controller is developed and adapted for both cylinders and PAMs. Experimentations show that the cascade scheme presents better results than state of the art sliding mode control: the predictive controller reduces the time response and guarantees good dynamic tracking while the H ∞ inner pressure controller provides more robustness relatively to load variations which are important requirements for pick-and place robotic tasks.Item Dynamic modeling and identification of Par4, a very high speed parallel manipulator(2006) Nabat, Vincent; Company, Olivier; Pierrot, François; Poignet, Philippe; Tecnalia Research & InnovationThis paper introduces the dynamic modeling and the identification of Par4, a four-degree-of-freedom parallel manipulator producing Schonflies motions (three translations and one rotation about a fixed axis). First of all, this paper presents how this robot is developed with the goal of reaching very high speed. Indeed, it is an evolution of Delta, H4 and I4 robots architectures: it keeps their advantages while overcoming their drawbacks. Experimentations done with the prototype prove that the robot is able to reach very high accelerations (15 G) and to perform an Adept cycle in 0.25 s. In order to improve its dynamic accuracy, a dynamic control could be necessary. Thus, this paper presents the dynamic modeling of the manipulator using a simplified Newton-Euler approach. The originality of this computation is to model the traveling as two separated parts and to determine the dynamic effects applied on each of them. Finally, since a dynamic control requires a good evaluation of dynamic parameters, an experimental dynamic identification is presented.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 Flexible model identification of the parallel robot par2(2010) Douat, Luiz R.; Queinnec, Isabelle; Garcia, Germain; Michelin, Micaël; Pierrot, François; Tecnalia Research & InnovationThe open-loop flexible modes identification of a high-speed and high-accuracy pick-and-place parallel robot is carried out based on two approaches: an ARMAX model and a subspace identification technique. Models of piezoelectric dynamics and disturbances can be obtained for many distinct operation conditions, allowing, in a future work, the conception of robust control laws.Item A generalized predictive force controller for electropneumatic cylinders(IFAC Secretariat, 2010) Chikh, Lotfi; Poignet, Philippe; Pierrot, François; Michelin, Micäel; Tecnalia Research & InnovationIs it possible to synthesize an easy-to-implement predictive force controller for electropneumatic cylinders? In this paper, this problem is treated in details. As an electropneumatic cylinder is a highly nonlinear actuator, our strategy is based on the precise nonlinear modeling of the actuator and the application of a feedback linearization strategy. This enables to have an equivalent linearized model and therefore, to find an explicit solution of the predictive optimization problem. The obtained controller is then an easy-to-implement one and the number of control parameters is very reduced: the weighting coefficient and the prediction horizon. Experimental results prove the availability of this control approach and good performances in terms of capacity of tracking long duration static forces of high amplitudes.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 H∞ control applied to the vibration minimization of the parallel robot Par2(2011) Douat, Luiz R.; Queinnec, Isabelle; Garcia, Germain; Michelin, Micaël; Pierrot, François; Tecnalia Research & InnovationConceived for high-speed and high-accuracy pick-and-place tasks, the parallel robot Par2 aims at reducing industrial operation cycle times. As a consequence of its high acceleration levels, the end-effector precision at the stop positions is subjected to undesirable vibrations of the manipulator's arms, leading consequently to an increase in the cycle time. Piezoelectric patches are wrapped around the robot arms in order to actively minimize these vibrations, which are by their turn measured by three accelerometers orthogonally oriented and placed on the end-effector. After submitting the robot to an identification procedure, the obtained model is used to synthesize a reduced order H∞ control law that succeeds in minimizing the residual vibrations.Item Identification and vibration attenuation for the parallel robot par2(2014-01) Douat, Luiz R.; Queinnec, Isabelle; Garcia, Germain; Michelin, Micaël; Pierrot, François; Tarbouriech, Sophie; Tecnalia Research & InnovationPar2 is a parallel robot with two degrees of freedom designed for high-speed and high-accuracy industrial pick-and-place operation tasks. As a result of the high acceleration trajectories, the end-effector undergoes some undesirable vibrations after reaching the stop positions, compromising its precision and leading to an increase in the operation cycle time. Accelerometer sensors placed on the end-effector and piezoelectric patch actuators wrapped around the robot arms are employed in order to actively reduce these vibrations in a noncollocated closed-loop setting. After submitting the robot to an identification procedure, the obtained nominal model is used to synthesize a reduced order controller with the H∞ loop-shaping technique. Performance analysis as well as simulation and experimental results show that vibration reduction is achieved around the nominal operating point, but fails for some extreme operating points, due to high control efforts. An anti-windup strategy is then employed to deal with the saturation of the actuator, which allows achieving vibration attenuation on the whole operation domain, for a given configuration of the robot at the stop point.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 mixed GPC-H∞ robust cascade position-pressure control strategy for electropneumatic cylinders(2010) Chikh, Lotfi; Poignet, Philippe; Pierrot, François; Baradat, Cédric; Tecnalia Research & InnovationA robust cascade strategy combining an outer position predictive control loop and an inner H∞ pressure control loop is proposed and tested on an electropneumatic testbed for parallel robotic applications. Two types of cylinders are tested, the standard double acting cylinder and the rodless one. A position/pressure difference (or force) strategy is developed and implemented. As the behavior of the nonlinear cylinders is nonlinear, a feedback linearization strategy is adopted. A Generalized Predictive Controller (GPC) is synthesized for the position outer loop and a constrained LMI based H∞ controller is synthesized for the pressure inner loop. Experimental results show the feasibility of the control strategies and good performances in terms of robustness and dynamic tracking.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 determination of cable characteristics for large dimension cable-driven parallel mechanisms(2010) Riehl, Nicolas; Gouttefarde, Marc; Baradat, Cédric; Pierrot, François; Tecnalia Research & InnovationGenerally, the cables of a parallel cable-driven robot are considered to be massless and inextensible. These two characteristics cannot be neglected anymore for large dimension mechanisms in order to obtain good positioning accuracy. A well-known model which describes the profile of a cable under the action of its own weight allows us to take mass and elasticity into account. When designing a robot, and choosing actuator and cable characteristics, a calculation of maximal tension has to be done. However, because cable mass has a significant effect on cable tensions, a model including cable mass has to be included in the design step. This paper proposes two methods to determine the appropriate cable and hence the maximal tensions in the cables. Applied to a large dimension robot, taking cable mass into account is proved to be necessary in comparison with an equivalent method based on the massless cable modeling. In this paper, only moving platform static equilibria are considered (slow enough motions).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.