A novel trajectory control and navigation analysis software approach is developed. The program quickly determines trajectory dispersions, navigation errors, and required maneuver Delta v at selected key points along a nominal trajectory. It can be used for mission design and planning activities or in autonomous flight systems to help determine the best trajectories, the best maneuver locations, and the best navigation update times to ensure mission success. These features are illustrated with two simple examples. The software works by applying linear covariance analysis techniques to a closed-loop guidance, navigation, and control (GNC) system. The nonlinear dynamics and flight software models of a closed-loop six-degree-of-freedom Monte Carlo simulation are linearized. Then, linear covariance techniques are used to produce a program that will accurately predict 3-sigma trajectory dispersions, navigation errors, and Delta v variations. Although the application presented is orbital rendezvous, the tools, techniques, and mathematical formulations are applicable to a variety of other space missions and GNC problems including atmospheric entry, low-thrust electric propulsion missions, translunar injection and lunar orbit insertion, lunar ascent/descent, and formation-flying missions.
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