Anti-disturbance Flight Control For Unmanned Helicopter Under Stochastic Disturbances

In this paper,the fight control is studied for the unmanned helicopter systems under stochastic disturbances.Due to the complicated and changing surroundings of the flying helicopter,the stochastic disturbances are considered in the unmanned helicopter models which will improve the control per-formance of the control systems.The stochastic disturbances are classified as different items,and are rejected and attenuated using different anti-disturbance control schemes.Uniting the disturbance-observer-based-control method and stochastic Markovian jump control system theory,several kinds of anti-disturbance flight controllers are designed for unmanned helicopter systems.The research results of this paper are given as follows:1.The problem of model reference resilient control is investigated for the unmanned helicopter systems with the time-varying disturbances,stochastic disturbances and unmeasurable states.A distur-bance observer and a state observer are built to estimate the time-varying disturbances and unmeasurable states.Combining the methods of model reference control and disturbance-observer-based-control,two kinds of robust resilient control schemes are proposed,which guarantee that the unmanned helicopter closed-loop tracking error systems are robustly stochastically stable with H_∞performance.Simulation results are presented to show the effectiveness of the model reference resilient control method.2.The tracking control problem is investigated for the unmanned helicopter under the time-varying disturbances,the input stochastic perturbations and the unmeasurable flapping motion states.A state observer and a disturbance observer are constructed to estimate the unmeasurable states and the time-varying disturbances,and the estimations of the disturbances are used in the feedforward controller design.Under the input stochastic perturbations,a feedback controller is constructed to guarantee the stochastic stability of the closed-loop error systems.Using the stochastic control theory and the linear matrix inequality technique,the stability of the closed-loop error systems is analyzed,and the gain of the controller is acquired via a solvable sufficient condition.An example is presented to illustrate the effectiveness of the proposed method.3.The issue of anti-disturbance control is investigated for the unmanned helicopter attitude and altitude systems with multiple stochastic disturbances.The disturbances are divided into two parts:one is described by the switching systems with Markovian jump parameters;the other one is from the stochastic modeling noise.Combining the disturbance-observer-based-control method,the backstep-ping control approach and the stochastic Markovian jump system control theory,a flight controller is constructed to guarantee that the attitude and altitude unmanned helicopter systems track the predefine attitude and altitude within reasonable bounds.Simulations are given to show the effectiveness of the proposed method.4.The stochastic robust anti-disturbance control is studied for unmanned helicopter systems under multiple stochastic disturbances.Combining the feedback linearization method,backstepping control scheme with disturbance-observer-based-control technology,a stochastic anti-disturbance flight controller is constructed for the full-degree-of-freedom unmanned helicopter systems to reject and at-tenuate the influence of these disturbances,and ensure that the predefined tracking tasks are achieved.Meanwhile,the boundedness in probability of tracking errors is guaranteed via the stochastic Marko-vian jump control system theory.An example is given to verify the effectiveness of the proposed control methods.5.The anti-disturbance fight/propulsion control is discussed for the nonlinear unmanned heli-copter systems with time-varying disturbances and stochastic disturbances.The engine control systems are controlled to maintain in a desired rotate speed.Based on the engine control systems,a flight controller is constructed by uniting the disturbance-observer-based-control method and other nonlinear control schemes.The stochastic stability control theory is used to prove the asymptotical bounded-ness in 4th moment of the closed-loop tracking error systems.Simulation results are given to show the effectiveness of the proposed control method.