Optimal control of a twin rotor MIMO system using LQR with integral action

The twin rotor MIMO system (TRMS) is a helicopter-like system that is restricted to two degrees of freedom, pitch and yaw. It is a complicated nonlinear, coupled, MIMO system used for system identification, the verification of control methods and observers. This paper details the design procedure for a suboptimal tracking controller using a linear quadratic regulator (LQR) with integral action. It was found that the LQR controller with integral action (LQI) provided performance superior to existing optimal controllers in the literature.