Anti-windup Control Strategy For A Multi-vectored Propeller Aerostat

The stability analysis and anti-windup controller design for a multi-vectored propeller aerostat with asymmetric constraints were addressed.The paper was organized as follows:A nonlinear dynamic model of the multi-vectored propeller aerostat was analyzed.The performance,including the maximum forward speed,the maximum vertical speed and the maximum yaw angular speed,was given based on the nonlinear model.Three typical kinematic modes: oscillatory mode,heave mode and surge mode were acquired from a linearized model.The disturbance responses of the nonlinear and the linear models at the equilibrium point were illustrated to validate the effectiveness of linearized model.A stability condition for the saturated closed-loop system was proposed and proved.First,a linear transformation was applied to transferring the asymmetric constraints into symmetric constraints with an amplitude-bounded exogenous disturbance.Then,a stability condition based on a quadratic Lyapunov function for the saturated closed-loop system was proposed.The condition took both amplitude-bounded exogenous disturbance and energy-bounded exogenous disturbance into consideration.The controller design problem was transformed into a convex optimization problem expressed in linear matrix inequality(LMI)form.Finally,a state feedback controller was designed.The simulation showed the effectiveness of the controller under disturbance.Two anti-windup controller design methods was proposed,including a direct method and an indirect method.The direct method got the controller and the compensator in one step while the indirect method separated this process into two procedure.First it got a controller without the consideration of saturation.Then a compensator was added to balance the saturation.Simulation results showed that both methods guaranteed the stability of saturation system.Given the flight model parameters and disturbance,the controller parameters can be calculated offline with both methods proposed in this paper,which lowereds the demand of the flight control computer.The methods can be tested in flight experiments.