Optimal Fractional Order PID based on a Modified Ziegler-Nichols method

Industry requires simple, yet efficient tuning methods for controllers. One of these tuning methodologies is the popular Ziegler-Nichols approach that requires little information regarding the process and has some pre-definite tuning rules. Although intensive research has been done in non-integer order controllers and their advantages have been demonstrated, their complexity and tedious tuning kept them away from industrial acceptance. In this manuscript, an existing Ziegler-Nichols method for fractional order controllers is modified to yield optimal parameters. The tuning rules and the optimization algorithm are simple, yet they lead to efficient fractional orders controllers. Simulation results are included to validate the proposed method.