FRACTIONAL ORDER PI λ D µ CONTROLLER: APPLIED TO CONTROL A MANIPULATOR ROBOT WRIST ZENNIR Youcef (a) , MAKHBOUCHE Adel (b) (a,b) Automatic Laboratory of Skikda, Route El-Hadeaik, BP26. 21000 Skikda, Algeria skikda.dz - adel.makbouche@univ (b) , skikda.dz - youcef.zennir@univ (a) ABSTRACT The work presented in this paper focuses on the use of multi- controller approach to control a robot wrist (STÄUBLI robot RX 90). A description and a nonlinear Mathematical model of process have been presented along with the local parametric models around operating points. Due to the advantage of fractional order PID control compared to conventional PID, a Fractional order PID controller has been developed around each selected operating points for each local parametric models with the Oustaloup recursive approximation method (ORA) method are presented. at the end we present the results obtained in the different simulations with 3D simulation robot model developed in CAO solid Works software and some perspectives for future work. Keywords: Modeling, Local Control, Multi-controller control, Fractional PID controller, Approximation Oustaloup method. 1. INTRODUCTION Invariant linear model for a physical process can only be an approximation. Indeed, a physical process generally has non-linearities (Slotine 1991) that are not taken into account in the modeling process. For some operating points of the physical process a local linear model can be determined. Two ways can be used to derive these linear models the first is based on the priori knowledge of the process and the second using identification. We may then seek to enslave the whole process in operational space using the local information (Balakrishnan 1994), (Chebassier, 1999). The objectives of this work are to develop a control structure in which control law is deduced from a set of controllers that are working together. The controllers parameters are deduced from the local models of the process. The purpose of the multi-controller command (Balakrishnan 1997) is to control the output of any process in space operation using controls developed by different local controllers. The diagram block of the multi-controllers control approach is represented as follows: Figure 1: Multi-controller structure approach. The multi-controller command is used to specify: • The controller’s structures. • The switching type (Pagès 2000; Duchamp 1998). Different solutions are proposed such as: • Fractional order PID controllers (Bensafia 2011). • Digital RST controller and Adaptive controllers (Karimi 1998) (Toscano 1997). • Frank or fuzzy switching (Pagès 2000; Foulloy 1998). • Direct or indirect approach to collaboration control law (Pagès 2000; Foulloy 1998). In our work we have choose the use of an indirect approach based on local fractional order PID controllers and frank switching for robot wrist control. 2. PROCESS MODELING The geometric series structure model of STÄUBLI Robot Rx-90 is give by the figure 2 (Khalil 2009): Proceedings of the Int. Conf. on Integrated Modeling and Analysis in Applied Control and Automation, 2015 ISBN 978-88-97999-63-8; Bruzzone, Dauphin-Tanguy, Junco and Longo Eds. 97