Modelling of a twin rotor system: a particle swarm optimization approach

A scaled and simplified version of a practical helicopter, namely the twin rotor multi-input multi-output system (TRMS) is often used as a laboratory platform for control experiments. This system resembles a helicopter in many aspects. Since the TRMS permits both 1 and 2 degrees of freedom (DOF) motions, it can be considered as a static test rig for an air vehicle. This study presents investigations into modelling of the TRMS using particle swarm optimization (PSO). First, 1-DOF models are extracted for both vertical (pitch) and horizontal (yaw) channels independently. Then, a 2-DOF parametric model is developed taking cross-coupling between the channels into consideration. A particle swarm algorithm that uses time-varying inertia weight factor and time-varying acceleration coefficients is considered in this work. The effectiveness of the algorithm in modelling the system is validated and verified in terms of tracking, stability, and ability of derived model in capturing the dynamics of the system. Time domain and frequency domain results of the derived models clearly show the potential of PSO in solving such control problems.