Hybrid QFT/H for control of nonlinear systems: An example of position control of a Pendulum

This work presents the control design of an uncertain nonlinear pendulum using a combined QFT/Hinfin technique. The uncertain nonlinear model of the plant is replaced by a set of linear time invariant equivalent (LTIE) plants through local linearization. The weight selections are then obtained from Hinfin theory to subsequently achieve a robust controller for the set of LTIE models. To enhance closed loop response characteristics, a pre filter analogous to quantitative feedback (QFT) design is incorporated. The single hybrid controller that combines the QFT and Hinfin control techniques ensures performance and robustness for the nonlinear pendulum. Simulations and experimental results are presented to validate the approach.