Scheme for the Balance Between Stability and Maneuverability of Hypersonic Vehicle

Since the aerodynamic center moving backward sharply in hypersonic flight,the stability margin of the hypersonic vehicle increases largely while the maneuverability decreases.We proposed a novel method to solve this contradiction.We used relaxed static stability(RSS)to improve the maneuverability in hypersonic flight,and designed the stability augmentation system(SAS)to ensure the stability in subsonic flight.Therefore,the relationship between static stability and maneuverability was quantitatively analyzed in the first step,and the numerical value of RSS was obtained on the premise of good maneuverability.Secondly,the relationship between static stability and aerodynamic parameters was quantitatively analyzed.We properly adjusted aerodynamic parameters based on the quantitative relationship to achieve the specific static stability set in the first step,and therefore provided the engineering realization methods.The vehicle will be statically unstable in subsonic flight with the specific static stability.Lastly,SAS was needed to ensure the stability of the vehicle in subsonic flight.Simulation studies were conducted by comparing the linear SAS to the nonlinear SAS,and the results showed that the nonlinear dynamicinversion controller can synthesize with proportional-integrall-derivative(PID)controller robustly and stabilize the hypersonic vehicle.

A novel approach to the attitude stabilization structure for ducted-fan operative aerial robots:Finding improvements for modeling error and strong external transient disturbance

This research concerns a novel attitude stabilization structure for a ducted-fan aerial robot to work against modeling error and strong external transient disturbance,and it focuses on two main control targets:modeling error compensation,and the improvement of disturbance resistance along the rolling channel.For the first research objective,we proposed an adaptive nominal controller with the reconfigurable control law design based on the estimation of the modeling error found in the closed-loop.Results of simulations and corresponding flight tests verified that the proposed adaptive control structure is robust against both constant and time-varying modeling error.For the other research objective,a SAC(Stability Augmentation Control)structure was devised based on the CMG(Control Moment Gyroscope)theory in order to provide extra moment which effectively withstands the transient disturbance beyond the CDG(Critical Disturbance Gain).Furthermore,we studied the corresponding controller for the SAC via the SMC(sliding mode control)theory,while the working mechanism and performance of the SAC were verified through a specially devised prototype.