SkySails Power attached to mast, ready to launch (August 2016)

96 SkySails towing kite being launched from catamaran Race for Water (April 2017)

97 SkySails towing kite being launched from catamaran Race for Water (May 2017)

98 Recent Advances in Automation of Tethered Flight at SkySails Power Manfred Quack, Michael Erhard SkySails Power GmbH

This contribution presents most recent advances in au- ditions, where significant heave, pitch and roll move- tomation of tethered flight at SkySails and the applica- ments can occur depending on the prevailing sea state. tion to yacht propulsion. Experimental data obtained Although the underlying feed-forward, feed-back control from the very recent Atlantic crossing of the yacht “Race approach is significantly relying on model information, For Waterž [1] will be presented. This solar yacht, weigh- data from flights at very low apparent wind speeds as ing approximately 100 metric tons and measuring 35 m, well as data from flight in rainy conditions show the ro- Manfred Quack features a propulsion system capable of running the bustness of this approach, in spite of the expected model Research & Development yacht by 100 % renewable energy and has recently been mismatch in such conditions. An analysis of propul- SkySails Power GmbH equipped with a SkySails kite system [2]. sive performance data shows that under ideal conditions, a 30 m2-sized kite alone can propel the ship to higher Tethered flight automation for at speeds than the 500 m2 on-board photovoltaic arrays, Luisenweg 40 SkySails has first been developed for traction of large ma- underlining the high power density of airborne wind en- 20537 Hamburg rine vessels [3] with kite sizes ranging from 20 m2 up to ergy, when comparing kite and photovoltaic array areas. Germany 320 m2. Subsequently, in order to demonstrate the ap- plicability of the kite system to electric power generation [email protected] References: from airborne wind energy in lift mode [4], flight automa- www.skysails.de tion algorithms have been extended to allow for optimal [1] http://odyssey.raceforwater.org pumping cycles [5] and demonstrated on a 55 kW small- [2] http://www.skysails-yacht.com scale functional prototype [6]. [3] Erhard, M., Strauch, H.: Control of towing for seagoing ves- In this work, experiences from both applications are sels. IEEE Transations on Control Systems Technology, 21(5), 1629ś merged to extend the flight automation algorithms for 1640 (2013) application to traction of yachts. Key novelties include [4] Loyd, M. L.: . Journal of energy, 4(3), 106ś111 the use of target point control in traction applications, (1980) a versatile control pod setup suitable for the use of a [5] Erhard, M., Strauch, H.: Flight control of tethered kites in au- range of different kite sizes and finally a stepping set point tonomous pumping cycles for airborne wind energy. Control Engi- 40 adaptation of the wind window angle for force control. neering Practice, , 13ś26 (2015) Flight test data from the yacht “Race For Waterž for kite [6] Erhard, M., Strauch, H., Diehl, M.: Automatic control of optimal sizes ranging from 20 m2 to 40 m2 shows that the con- pumping cycles in airborne wind energy. In Book of Abstracts, Air- trol approach is suitable for application in offshore con- borne Wind Energy Conference, June 15ś16, Delft (2015)

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