Implementation and Test of a Semi-Closed Loop HHC-Algorithm with the DLR’S Multiple Swashplate System

This paper discusses the design, integration and test of a Higher Harmonic Control algorithm capable of both vibration control and in-flight blade tracking in conjunction with DLR's multiple swashplate control system (META). The design of the control algorithm is described in detail and the results of coupled numerical investigations with both MbDyne and DLR's comprehensive rotor code to determine the algorithm's performance, are presented. The integration of the control-algorithm into the realtime control software is shown for the META system, where for safety reasons a semi-open loop approach was implemented. First tests of the controllers in-flight tracking mode to reduce 1/rev loads during hover have successfully been conducted at the DLR's rotor test facility, yielding a 94.2% reduction in 1/rev vibratory loads while maintaining constant rotor thrust.