Browsing by Author "Poignet, Philippe"
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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 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 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 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 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 A predictive robust cascade position-torque control strategy for Pneumatic Artificial Muscles(IEEE Computer Society, 2010) Chikh, Lotfi; Poignet, Philippe; Pierrot, François; Michelin, Micaël; Tecnalia Research & InnovationA robust cascade strategy is proposed and tested on an electropneumatic testbed for parallel robotic applications. It is applied on Pneumatic Artificial Muscles (PAMs). Nonlinear models are developed and presented. By specifying the pressure average between the two muscles, it is possible to control the torque by controlling the pressure in each muscle. A constrained LMI based H ∞ controller is synthesized for the pressure inner loop. A computed torque is applied on the torque loop and a Generalized Predictive Controller (GPC) controller is then applied to control position of the muscles. Experimental results show the feasibility of the control strategy and good performances in terms of robustness and dynamic tracking.