Research On Several Key Technologies For Unmanned Helicopter Flight Control

Unmanned helicopter owns basic abilities with the help of the primary control strategy, which,however, could not obtain advanced performances, especially in complex environment. The problemsexisted in the primary control strategy make it difficult to satisfy the requirement of application for theunmanned helicopter. To improve the flight performance for unmanned helicopter in complexenvironment, advanced control strategy is presented, which based on the primary control strategy.The primary hover control law is difficult to obtain high precision for position control on theeffect of dynamic wind. However, a high precision position control scheme based on nonlinear PID ispresented. The scheme increases position control precision by nonlinear feedback technology, whichbenefits the auto landing.The primary forward flight control law could not adjust the disturbance due to crosswind, whichresults in big sideslip angle. To reject the disturbance due to crosswind, two anti-crosswind strategiesare presented, contain the head-free anti-crosswind strategy, which rejects the crosswind bydirectional static stability, and the lateral overload control strategy, which reject the crosswind bycontrolling lateral overload, which is equivalent to sideslip angle.To improve the primary transition control strategy, which can not satisfy the constraints of heightand hovering position, a transition control strategy based on height trajectory and ground velocityversus range-to-go profile. With the strategy, the whole transition process is divided to three phases,named height transition phase, velocity transition phase and position transition phase, whichaccomplish the transition task cooperatively.Integrated simulation is carried out to evaluate the performances of the advanced control strategy.The simulation result indicates that the high precision position control scheme could obtain highprecision for position, which improves the safety for auto landing; the two anti-crosswind strategiescould reject the disturbance due to crosswind, with small sideslip angle; the transition strategy couldsatisfy the constrains of height, velocity and hovering position.