Songyan Wang

Moving-Mass Trim Control System Design for Spinning Vehicles

The ability of a moving-mass control system to control the attitudes of a spinning vehicle is investigated. For the self-learning and adaptive abilities of neural networks, the hybrid attitude control scheme is produced to improve the dynamic performances of the complicated nonlinear system. An analysis of the torque disturbances caused by the relative movements of the masses to the vehicles body reveals that the total movements of the masses are inclined to be minimized to mitigate these coupling effects. And based on the optimal theory, the mass position algorithm, which determines the mass location to realize the offset of the center of mass of system, is designed. A nonlinear eight degree-of-freedom simulation of a spinning vehicle with two internal moving elements demonstrates the abilities of the hybrid attitude control scheme and the mass position algorithm to effectively control the attitudes of spinning vehicles

Multiple missiles cooperative guidance based on leader-follower strategy

According to the characteristics of multiple missiles cooperative guidance, a time-cooperative guidance architecture based on leader-follower strategy is proposed. This architecture is composed of individual guidance for each missile and coordinating strategy of the whole system. The central process unit situated at the leader coordinates the system, and the cooperative information is broadcasted from leader to followers. The coordinate information includes expected impact time and relative motion information of leader and target. The time-cooperative guidance architecture has the characteristics of brief structure, short coordinate time and little information to hand on. For the features of structure and the follower have no seeker, a specific and feasible algorithm of line of sight rate is presented, the requirement of follower computation and detection equipment is decreased. Simulation results show the proposed architecture can realize coordinated attack effectively.

Moving-mass control system for spinning vehicle guidance based on GA

The ability of a moving-mass trajectory control system to control a spinning vehicle is investigated. The nonlinear equations of system motion with two internal moving elements are provided, and the influence to the system of moving-mass movements with respect to the vehicles body is described. For the complexity of the nonlinear moving-mass control system, the effectiveness of each element of governing equations is analyzed to indicate the controllability of system in theory. For the parameter search capacity of genetic algorithm, the hybrid trajectory control scheme, which calculates the desired offset of the center of mass of system to realize the corrections of the vehicles trajectory, is produced to improve the dynamic performance of the system. A nonlinear eight-degree-of-freedom simulation of a typical mission profile demonstrates the ability of the hybrid controller to effectively control the vehicles trajectory

Integrated guidance and control design considering system uncertainty

The hypersonic vehicle has the characteristics of strong coupling, high uncertainty and complex nonlinearity, leading to an unsatisfactory control performance with the traditional design method. In this paper, an integrated guidance and control design approach is proposed to cope with this problem. A time-varying longitudinal integrated guidance and control model is first formulated, and then the overall uncertainty consisting of the un-modeled dynamic, parameter uncertainty and external disturbance is taken into account. A novel finite-time extended state observer is developed to estimate and compensate it in real time. Furthermore, an integrated guidance and control algorithm utilizing back-stepping method and the dynamic inverse is put forward. It has been theoretically proved that the finite-time extended state observer system and the cascade system are globally finite-time stable. Numerical simulation results under different kinds of uncertainty with different amplitude and frequency are presented to illustrate the effectiveness and feasibility of the proposed approach. The proposed integrated guidance and control possesses a better convergence performance and stronger disturbance rejection property in existence of the mismatched uncertainty and parameter uncertainty.

Multiple flight vehicles cooperative guidance law based on extended state observer and finite time consensus theory

An extended state observer based cooperative guidance method is proposed for multiple flight vehicles intercepting a coming maneuver target. The guidance geometry for multiple flight vehicles-target is established, and a cooperative guidance law used multi-agent cooperative control theory is designed for multiple flight vehicles. To deal with the uncertainty of the maneuver target, the target acceleration is considered as a disturbance, which is observed using an extended state observer, and compensated in the guidance law. Simulation results show that the designed extended state observer can estimate the target acceleration accurately, and the proposed cooperative guidance can satisfy the demands for controlling the intercept time, and hence the cooperative interception can be achieved.

Continuous non-smooth approach based terminal guidance law with extended state observer

In this paper terminal guidance law considering uncertain factors for flight vehicle is investigated. In order to improve the terminal guidance accuracy, continuous non-smooth control theory based nonlinear guidance law which can make the states converge in finite time is derived. Then a finite-time convergence extended state observer is introduced into the control system for compensating the uncertainties in it. With the aid of numerical simulation, it demonstrates the effectiveness of the approach to yield better terminal accuracy in the presence of abrupt disturbance.

Trajectory tracking control based on improved particle swarm optimization

Since the tightly coupled, highly nonlinear and notoriously uncertain nature of hypersonic flight vehicle(HFV) dynamics, any state which does not meet the constraint may lead the system states to diverge. In this paper, differential flatness approach is applied to linearize the longitudinal model of HFV. According to the established trajectory, all the time-varying states and control inputs can be obtained by differential flatness approach, which is advantageous to protect states from exceeding the constraint before flight simulation. A state feedback controller is proposed. An improved particle swarm optimization algorithm is proposed to obtain the optimal parameters, which can ensure both convergence property of the system and large enough search space of parameters. A case study is presented to illustrate the effectiveness of the proposed methodology.

Improved semi-major axis iterated method for Lambert's problem

Lamberts problem, as the basis of designing the transfer orbit is reviewed. According to the Lagrange equations, the available range of the transfer time is proposed, then, the improved method for the Lamberts problem and the calculation method of part of the orbital elements basing on the thought of the semi-major axis iterated are obtained. Furthermore, the Newton iteration method is used in solving the semi-major axis, which has improved the computational efficiency. Then, through analyzing the results calculated by the classic Battin-Vaughans solution and the improved semi-major axis iterated method, the new method is proved efficient and accurate. Finally, the formulas of elliptic orbit, hyperbolic orbit and the parabolic orbit derived from the orbital elements are given.

Adding a power integrator technique based terminal guidance law

In this paper a novel terminal guidance law for hypersonic vehicle is investigated. In order to accelerate the convergence rate of line of sight angle, adding a power integrator technique based nonlinear guidance law which can make the line of sight converge to zero in finite time is proposed. Then rigorous stability analysis of finite-time convergence is shown. It demonstrates the effectiveness of the approach by numerical simulation meanwhile the approach have strong robustness in the presence of disturbance.

Finite-time convergent sliding-mode guidance law based on Extended-State-Observer

Fast maneuvering target may lead to the guidance law providing a lower terminal precision. In order to solve this problem, a finite-time sliding-mode guidance law based on Extended-State-Observer(ESO) is proposed. First of all, guidance law design model is established based on two-dimensional relative motion model. Aiming at the design model, combine the theory of finite-time control and sliding-mode variable structure control method to design a finite-time sliding-mode guidance law. Then, a finite-time ESO is designed to estimate target-maneuver and compensate it in designed guidance law. It is theoretically proved that the designed guidance law can guarantee the stability of the system state. Finally, verify the effectiveness of the designed guidance law by means of numerical simulation.