Sequential control is one of the most successful multi-loop methods for enhancing the performance of linear controllers. This method
can improve the effectiveness of control strategy and minimizes the disturbance impact. To achieve good control performance it is
important that the parameters of the sequential controller be appropriately and precisely. Thus, having sufficient insight into process
performance and dynamics of the system is necessary for designing sequential control. Sequential controls are usually designed using
Nichols or Bode diagram that have high complexity of the analysis.
The methods mentioned can be used for linear systems, but if the system is nonlinear, designing will be difficult. Intelligent
techniques of optimization such as Firefly Algorithm have proven their capabilities in designing the controllers. In this paper, we aim
at designing sequential controllers for controlling robotic arm in the presence of external disturbances. Designing method based on the
firefly algorithm is described. Results of simulation and performance of the controller are also presented.