Optimal control for hover pendulum motion of unmanned helicopter

Purpose During the authors’ practical experiments about designing hover controller for unmanned helicopter, they find pendulum motion exists, thus destroying their expected control performance, such as perfect tracking, target detection, accurate attacking etc., so they turn to study how to suppress pendulum motion through designing one additional controller to guarantee pendulum motion sufficiently small. More specifically, the detailed mechanism of hover pendulum motion is analyzed to yield one accurate nonlinear dynamical equation, corresponding to hover pendulum motion. To apply the existed linear optimal control strategy directly, the necessary linearization process is needed to derive one approximated linear state equation, including the explicit form of control input. After describing their idea about pendulum control structure from the point of practice, linear optimal control strategy is proposed to design the ideal controller without external noise. Then its improved robust controller is also given through solving their difference game problem or min-max problem. From their obtained closed forms of the pendulum controller, they are all one linear state feedback form, being convenient to implement in practical engineering. Finally, to achieve the mission of theory for application, they use their established practical platform to do some simulations, so proving the theoretical results. The purpose of this paper aims to design one optimal controller to suppress hover pendulum motion for unmanned helicopter. Design/methodology/approach First, considered the practical hover motion of unmanned helicopter, its detailed mechanism is analyzed to get one linear state equation after the authors’ complex mathematical derivation. Second, their idea of control structure and control design is applied to design one linear state feedback controller through the derived optimal control strategy. Third, one practical platform is established to prove their control idea. Findings From the authors’ introduction and knowledge, control exists everywhere. As unmanned helicopter has become increasingly important as one tactical weapon, so they think how to design controller for hover pendulum motion, while suppressing the hover pendulum. Specifically, they give the detailed theoretic derivation and practical platform. Originality/value To the best knowledge of the authors’ knowledge, pendulum motion control is to stop the swing as soon as possible and suppress the oscillatory motion of pendulum angle. Then, based on that linear state equation for hover pendulum motion, linear optimal control strategy is applied to achieve above two dual missions, i.e. controlling the motion or pendulum suspension point and eliminating or suppressing the pendulum phenomenon.