Operations in proximity of minor bodies demands high levels of autonomy to achieve cost-effective safe and reliable solutions.Autonomous trajectory and operations planning capability plays a pivotal role in this.A goa...Operations in proximity of minor bodies demands high levels of autonomy to achieve cost-effective safe and reliable solutions.Autonomous trajectory and operations planning capability plays a pivotal role in this.A goal-oriented guidance strategy for on-board implementation is presented in this paper to achieve high level mission objectives with impulsive control capability.The methodology is based on abstract reachability analysis performed on the control domain combining model predictive control theory with artificial potential fields algorithms.The formulation of the optimization problem in a general and flexible way allows to target different goals while being compliant with an arbitrary number of mission constraints.In particular,two main contributions to the field are proposed in this work:a way of embedding non-uniform observation constraints in the formulation to deal with challenging illumination conditions,and the inclusion of specific operational constraints to be compliant both with ground operations and on-board replanning.The methodology is applied to the Milani mission,one of the two Hera’s CubeSats,targeting a global coverage of the main attractor,Didymos,and detailed observations of specific features on the secondary asteroid,Dimorphos.The authors,being involved in the mission analysis,image processing,and GNC design of the platform,believe that this methodology also represents a viable tool for efficiently generating flight dynamics references during operations.Different metrics are investigated to achieve mission objectives leading to four application scenarios that are discussed in this work.Results are compared in terms of computational cost,convergence properties and efficiency.These results represent a step forward in enabling autonomous guidance capability for CubeSats proximity operations.展开更多
A novel Mars orbit insertion strategy that combines ballistic capture and aerobraking is presented.Mars ballistic capture orbits that neglect the aerodynamics are first generated,and are distilled from properly comput...A novel Mars orbit insertion strategy that combines ballistic capture and aerobraking is presented.Mars ballistic capture orbits that neglect the aerodynamics are first generated,and are distilled from properly computed stable and unstable sets by using a pre-established method.A small periapsis maneuver is implemented at the first close encounter to better submit a post-capture orbit to the aerobraking process.An adhoc patching point marks the transition from ballistic capture to aerobraking,from which an exponential model simulating the Martian atmosphere and a box-wing satellite configuration are considered.A series of apoapsis trim maneuvers are then computed by targeting a prescribed pericenter dynamic pressure.The aerobraking duration is then estimated using a simplified two-body model.Yaw angle tuning cancels the inclination deflections owing to out-of-plane perturbation from the Sun.A philosophy combining in-plane and out-of-plane dynamics is proposed to simultaneously achieve the required semi-major axis and inclination.Numerical simulations indicate that the developed method is more efficient in terms of the fuel consumption,insertion safety,and flexibility when compared with other state-of-the-art insertion strategies.展开更多
文摘Operations in proximity of minor bodies demands high levels of autonomy to achieve cost-effective safe and reliable solutions.Autonomous trajectory and operations planning capability plays a pivotal role in this.A goal-oriented guidance strategy for on-board implementation is presented in this paper to achieve high level mission objectives with impulsive control capability.The methodology is based on abstract reachability analysis performed on the control domain combining model predictive control theory with artificial potential fields algorithms.The formulation of the optimization problem in a general and flexible way allows to target different goals while being compliant with an arbitrary number of mission constraints.In particular,two main contributions to the field are proposed in this work:a way of embedding non-uniform observation constraints in the formulation to deal with challenging illumination conditions,and the inclusion of specific operational constraints to be compliant both with ground operations and on-board replanning.The methodology is applied to the Milani mission,one of the two Hera’s CubeSats,targeting a global coverage of the main attractor,Didymos,and detailed observations of specific features on the secondary asteroid,Dimorphos.The authors,being involved in the mission analysis,image processing,and GNC design of the platform,believe that this methodology also represents a viable tool for efficiently generating flight dynamics references during operations.Different metrics are investigated to achieve mission objectives leading to four application scenarios that are discussed in this work.Results are compared in terms of computational cost,convergence properties and efficiency.These results represent a step forward in enabling autonomous guidance capability for CubeSats proximity operations.
基金This work was supported by the National Natural Science Foundation of China(No.11602301)the Science and Technology Laboratory on Space Intelligent Control for National Defense(No.KGJZDSYS-2018-12)the National Key R&D Program of China(No.2019YFA0706601).
文摘A novel Mars orbit insertion strategy that combines ballistic capture and aerobraking is presented.Mars ballistic capture orbits that neglect the aerodynamics are first generated,and are distilled from properly computed stable and unstable sets by using a pre-established method.A small periapsis maneuver is implemented at the first close encounter to better submit a post-capture orbit to the aerobraking process.An adhoc patching point marks the transition from ballistic capture to aerobraking,from which an exponential model simulating the Martian atmosphere and a box-wing satellite configuration are considered.A series of apoapsis trim maneuvers are then computed by targeting a prescribed pericenter dynamic pressure.The aerobraking duration is then estimated using a simplified two-body model.Yaw angle tuning cancels the inclination deflections owing to out-of-plane perturbation from the Sun.A philosophy combining in-plane and out-of-plane dynamics is proposed to simultaneously achieve the required semi-major axis and inclination.Numerical simulations indicate that the developed method is more efficient in terms of the fuel consumption,insertion safety,and flexibility when compared with other state-of-the-art insertion strategies.
