采用有限推力的火星捕获制动策略

Capture and Brake Strategy for Mars Explorer with Finite-Thrust

针对火星探测的捕获制动问题,建立了描述推力沿速度反方向、推力方向固定和推力匀速转动3种制动策略的有限推力模型。以消耗的燃料质量和入轨近火点的高度误差为双目标,利用多目标粒子群算法优化控制参数,得到多目标问题的Pareto非劣解集和Pareto前沿。仿真校验时采用均匀设计法初始化种群,发现推力沿速度反方向时捕获效率最高;方向固定时近火点高度误差小;推力匀速转动会抬升近火点高度,但推力方向与速度反方向夹角小,燃料消耗较少。推力方向匀速转动的策略可以作为优先选用的策略,当出现故障需紧急制动时可启用推力沿速度反方向策略,控制探测器先被火星捕获。仿真表明双目标优化可比燃料最优的单目标提供更全面的决策信息,有助于确定设计方案。

To solve the capture and brake problem of Mars prober, this paper establishes the model of finite-thrust, involving three different strategies. Multi-objective particle swarm optimization algorithm is used to minimize both fuel consumption and periapsis distance error, and method of uniform design is applied to initialize particle populations. After simulation, Pareto-optimal set and Pareto front are obtained. It＇s indicated that capture strategy of fixeddirection thrust produced smaller periapsis distance error, whereas capture process where thrust direction is anti- parallel to velocity saves more fuel due to less gravity loss. Periapsis height is increased for strategy with constant rotation rate of thrust, and fuel consumption is moderate because of small angle between thrust direction and reverse direction of velocity vector. The idea of two optimized objectives can provide more comprehensive decision-making information than single objective of fuel consumption.