The Modelling Simulation and Control of Helicopters Operating With External Loads

The paper reports progress made on a project concerned with the modelling, simulation and control of helicopters operating with external loads. The project objective is to investigate control schemes that ensure that safe handling qualities are maintained throughout the widest possible flight envelope, whilst taking a holistic view of such operations. The use of co-operative lift and associated modelling and operating issues is a central theme of the project. The concept uses multiple helicopters to carry heavy or bulky loads that could not be carried using a single helicopter alone. The modelling and simulation aspects of the project have incorporated some novel new approaches to modelling slung load systems using commercial software including Matlab Simulink, SimMechanics and FLIGHTLAB. Matlab Real-Time xPC Target was used to integrate the Matlab slung-load models with the HELIFLIGHT motion simulator at The University of Liverpool. This enabled the dynamics and stability of slung load configurations to be analysed offline before performing piloted closed-loop tests. The paper describes the approach taken and shows the key results from preliminary handling qualities analysis.