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This article deals with the problem of robust fractional-order fixed-structure controller design for commensurate and non-commensurate fractional-order interval systems using fractional Kharitonov theorem. The contribution of this study is to develop a simple control methodology to stabilize the fractional-order Kharitonov-defined vortex polynomials. Using the idea of robust stability testing function and extending it to the systems under study, the straightforward graphical and systematic procedures are proposed to investigate the robust stability of the system by searching for a non-conservative fractional-order Kharitonov region in the controller parameters plane. This region can establish all the fractional-order controllers that make the uncertain fractional-order systems stable. The relation between the fractional-order Kharitonov region and the parameters of the stabilizing controller is also found. Finally, comparison results with three relevant works are given to illustrate the feasibility of the proposed method.

The particular family of lower mobility parallel manipulators by employing modified version of Delta robot is proposed in this paper. The proposed novel mechanism like ordinary Delta parallel mechanism has three degrees of pure translational freedom. One of the main differences between this mechanism and Delta parallel mechanism is the position of robot's three active joints relative to each other which has caused the change in geometry of platforms, and shapes the asymmetrical structure in the robot mechanism and its workspace. Another difference arises from an architectural optimization methodology by consideration of mixed performance index which has been utilized in this mechanism for reaching a better compromise between the dexterity of manipulator and its workspace. After introducing architecture of the robot, developed kinematic closed-form solution is verified using MSC.Adams©. Then Jacobian matrix is generated in order to evaluate the singularity problem of proposed mechanism. After that, workspace of the robot is investigated and compared with ordinary Delta mechanism.