Practically Implementable Model Predictive Controller for a Twin Rotor Multi-Input Multi-Output System

Abstract

Model Predictive Control (MPC) is a well-established control strategy for the optimal control of constrained multivariable systems. Twin Rotor Multi-Input Multi-Output System (TRMS) is a nonlinear system with significant cross-coupling between the horizontal and vertical axes presenting formidable challenges in modelling and control design. There are instances when a theoretical design may pose problems when it comes to practical implementation, particularly when the design is for nonlinear systems. In this context, this paper presents a practically implementable MPC design for TRMS which has been implemented successfully on a laboratory TRMS test-rig. The presented design is more suited for TRMS because it can handle the control constraints associated with the system through the optimization algorithm underlying the MPC scheme. From the view point of the system, all the control objectives are addressed, viz., stabilizing the system in a coupled condition and making its beam to track a specified reference trajectory or reach desired positions in 2DOF (two degrees of freedom) without violating the control input constraints. The design also incorporates the disturbance rejection requirement. Both simulation and experimental results are presented to show that the results from practical implementation are in accordance with the simulated results.