基于非线性预测方法的开关式导引律设计

以大气层外拦截为背景,研究了带有开关输入的不确定非线性系统的预测控制方法。根据Fliess级数展开理论,得到了系统输出预测值与控制输入以及不确定性的关系式。通过选择二次型代价函数,得到了预测控制中优化问题的描述。由于代价函数中含有不确定性,结合开关控制输入的特点,给出了一种应用非线性规划求解优化问题的方法。最后,将该方法应用到大气层外拦截中,考虑弹-目相对距离及视线转率存在不确定性的情况,设计了开关导引律,并给出了代价函数中加权系数的选择方法。仿真结果表明,该方法在保证拦截精度的情况下,减少了发动机的开关次数。

Design of on-off guidance law based on nonlinear predictive control

For the exo-atmospheric interception,the model predictive control(MPC) of nonlinear systems with uncertainty and on-off inputs is studied.The Fliess functional expansion is used to describe the relationship between the outputs and both control inputs and uncertainty.Using the quadratic criterion,the optimal control problem of MPC is obtained.In order to deal with the uncertainty in criteria,a solving method of optimization,which uses nonlinear programming and combines the characteristic of on-off inputs,is proposed.Finally,the method is applied to exo-atmospheric interception.In the case of an uncertain relative distance and the rate of line-of-sight,the on-off guidance law is designed.The simulation results show that the proposed method guarantees high interception accuracy and reduces the on-off times of the thruster.