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.