Design of two-layered fractional order fuzzy logic controllers applied to robotic manipulator with variable payload

• Two-layered fractional order fuzzy logic controller (TL-FOFLC) is implemented for robotic manipulator.
• The optimal controller parameters are obtained with cuckoo search algorithm.
• Robustness analysis of proposed scheme is done with its integer order design, conventional FLC and PID controllers.
• The proposed scheme outperforms its integer order design, conventional FLC and PID controller.

The robotic manipulators are highly coupled and nonlinear systems wherein the time-varying parameters and uncertainties adversely affect the characteristics and response of these systems. Hence, these systems require an effective and robust controller to handle such complexities which is a difficult challenge for control engineers. This paper presents two-layered fractional order fuzzy logic controller (TL-FOFLC) scheme for a two-link planar rigid robotic manipulator with payload for trajectory tracking task. For the optimal design, the controller parameters of the proposed scheme are obtained with potential meta-heuristic technique named as cuckoo search algorithm (CSA). In order to ensure effectiveness, the performance of proposed TL-FOFLC is compared with that of its integer order design approach, i.e., two-layered FLC (TL-FLC), single-layered FLC (SL-FLC), and the conventional proportional-integral-derivative (PID) controllers. Further, the robustness testing is carried out for parameter variations and external disturbance rejection.