Browsing by Author "Chikh, Lotfi"
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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 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 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.Item Some investigations into the optimal dimensional synthesis of parallel robots(2016-04-01) Kelaiaia, Ridha; Zaatri, Abdelouahab; Company, Olivier; Chikh, Lotfi; Tecnalia Research & InnovationIn this paper, we will perform a comparison between two approaches of dimensional synthesis of parallel robots. The first one concerns the single-objective optimization approach; in this case, the dimensional synthesis is expressed by taking into account only one performance criterion but enables to get a final solution if it exists. The second one concerns the multi-objective optimization approach; it enables to simultaneously take into account several performance criteria. However, this approach appears to provide a set of solutions instead of a single expected final solution which should directly enable to carry out the structural synthesis. In fact, the search of a single final solution is postponed to a further step where the designers have to impose and/or restrict certain parameters. And we will establish if it is really necessary to make a multi-objective optimization approach or if a single-objective is sufficient to reach the objectives set in the specifications (user requirements). A discussion is proposed concerning the arising questions related to each approach and leading to the optimal dimensional synthesis. The PAR2 robot with two degree-of-freedom is used to exemplify the analysis and the comparison of the two approaches. The proposed comparison can be applied to any classes of parallel robots.