Comparative Study of Speed Control Algorithms for UAV Applications

This paper presents performance comparison of three speed control schemes (engine throttle control) for LAV applications. First scheme uses fixed throttle levels (three levels for cruise climb and descend) however no speed feedback was used in the control loop. Second scheme also uses fixed throttle levels however number of levels are increased and switching is performed based on speed feedback using rule based decisions making techniques. Third scheme uses modern robust speed control, designed using H_infin loop shaping. The H_infin controller design requires an accurate linear model, which was obtained by system identification using available nonlinear simulations. The proposed algorithms were implemented in C/C++ and tested in 6-DOF simulations. Simulation results showed that the rule based decision making scheme gave acceptable performance, however the H_infin controller worked better in the presence of disturbances in all flight conditions e.g. cruise, climb, descend and rolling keeping speed in a small band of a fixed reference value.