Fractional order multi-controller design to control a manipulator robot wrist

The paper presents a new multi-controllers approach of control applied to control a manipulator robot wrist (Staubli RX-90). A brief overview of the process with a non-linear and linear mathematical modeling of the process. Principle of multi-controllers approach of control is briefly presented. Our new proposals concerning the type of the controllers used in the multi-controller approach of control and which are robust fractional order controllers (as FOPID and FOPI) to improve the robustness of the control. Two approximation methods used to approximate the fractional order (recursive approximation method (ORA) of Oustaloup for FOPID and singularity function method of Charef for FOPI). Controllers´ synthesis with the principle of approximation methods is presented. Different simulations were performed to illustrate the effectiveness of the new multi-controllers structures of control and also to differentiate approximations methods with the settings parameters controller and the approximation order followed by a conclusion and some perspectives for future work.