Dynamic Matrix Control of a 3DOF Helicopter with Stabilising Inner Loop

This paper investigates the use of a dual-loop control system for a laboratory helicopter with three degrees of freedom, namely pitch, elevation and travel. The goal consists of following a travel reference at constant elevation while limiting pitch excursion. A first-principles model of the helicopter was initially employed to design the inner loop through a Discrete Linear Quadratic Regulator (DLQR) formulation. With this stabilising controller in place, the step response to a travel command was acquired to design a Dynamic Matrix Control (DMC) scheme with pitch constraints. The dual-loop architecture was implemented in a multirate manner, with DMC acting as a command governor for the DLQR controller. Experimental results are presented to show the efficacy of the overall control system.