This paper is devoted to modelling and control algorithms for a load transportation system composed of one or multiple helicopters, where the load is coupled by the means of flexible ropes. The coupled helicopter system allows overcoming the payload limitation of a single small size helicopter and keeps most of its advantages, like small costs of operation, low maintenance costs and increased safeness due to the lower mass and size of the rotor blades. Therefore the system can be utilized whenever the use of full size helicopters is impossible, too expensive or prohibited by law. We are working on the deployment and repairing of distributed sensor networks using a transportation system based on multiple small size helicopters. Other applications would be the deployment of fire fighting equipment, e.g. gas masks, on a roof of a burning building, where it is too dangerous to use full size helicopters and there is not enough room in the fire trucks to carry bigger UAVs with them. The problem of load transportation using one or two full size helicopters (twin lift helicopter system) connected to the load by means of flexible ropes has been discussed in the aerospace research community at least since 1960. As we have shown in our previous work there is a fundamental difference in the mathematical description between small and full size helicopters. Therefore, also the control design for the case of small size helicopters is different. To our knowledge the control of a load transportation system composed of small size helicopters has not been studied until now. In this paper the complete mechanical setup of the load transportation system based on one or more small size helicopters will be presented. This includes a short description of the used UAVs, explanations what types of additional sensors are needed and how the load is mounted. A model of one/multiple helicopters transporting a load is introduced. This model is used in simplified form for the controller design and in full form for simulation. The controller for one and two helicopters, which is based on a state feedback controller, as well as the controller for three and more helicopters, which is based on a non linear controller, will be explained in detail. Both controllers utilize an underlying non-linear orientation controller. To increase the robustness and performance of the system a compensator feedback loop, based on forces measured in the ropes, is proposed. The controllers were tested in simulation using the full non-linear model of the helicopter(s) coupled to the load using ropes. Real flight experiments were successfully conducted during autumn and winter of 2007 and their results are presented in the work.


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    Title :

    Load transportation system based on autonomous small size helicopters


    Contributors:


    Publication date :

    2008


    Size :

    9 Seiten, 14 Bilder, 6 Quellen



    Type of media :

    Conference paper


    Type of material :

    Storage medium


    Language :

    English






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