An efficient fractional-order self-adjusted fuzzy PD regulator for nonlinear mechanical systems

In this paper, a novel smart control scheme, namely, Fractional-Order Self-Adjusted Fuzzy Proportional plus Derivative, i.e., FOSAFPD regulator is proposed for mechanical systems. The scheme is evaluated for effective control of a nonlinear mechanical Single-Input and Single-Output system (SISO), i.e., the tractor's ' s active suspension system, and a Multi-Input and Multi-Output system (MIMO), i.e., coupled double pendulum system. The FOSAFPD regulator is a Takagi-Sugeno model-based self-regulated adaptive regulator containing a non-integer order differential operator. It possesses nonlinear behaviour and adjusts the scaling factors based on error and its rate of change at run-time. The closed-loop performance of the FOSAFPD regulator is assessed with its integer order counterpart, Integer-Order Self-Adjusted Fuzzy Proportional plus Derivative (IOSAFPD) regulator. The scaling factors of FOSAFPD and IOSAFPD regulators were tuned using the Grey Wolf Optimization technique. Further, both the regulators are critically tested for measurement noise and latency in the control signal and feedback loop. The presented simulation study revealed that the FOSAFPD regulator outperformed the IOSAFPD regulator both in SISO and MIMO systems.