Precision Control Autonomous Systems for NEO Mission Design

Precision Control Autonomous Systems for NEO Mission DesignKarl WilliamsMatthew ZimmerProject Basis / MotivationAsteroid mission has received a lot of attention in recent yearsDefense, economic and exploration purposes

Current missionsDAWN and HAYABUSA II (2014-15 Launch)

Orbital control as not been demonstrated around objects of small diameters500 meter in diameter scaleLets Look at an Example.

Classifying the ProblemNeed to determine regions of natural stabilityBalance between complex gravitation, solar radiation pressure and third body perturbationsWhich orbital parameters are needed such that our spacecraft stays in orbit for a longer duration of time disregarding external control

Standardizing the ModelRunning multiple simulations on different computersProne to error due to changing initial conditionsAsteroid characteristicsEpochRotationGravity ModelCreate a standard satellite model Surface AreaDry MassFuel mass

25143 Itokawa (JAXA 2005)Standardizing the ModelCustom Ion Engine ModelMaximum & Minimum PowerSpecific ImpulseMass Flow Rate

Based on existing 8 cm Ion Engine*

*L3 Communications

PID ControlProportional, Integral, Derivative ControlError Function: Current altitude vs desired altitudeExecutionProportional push based on errorIntegral constant summation (plus correction) of the error over the simulation Derivative monitors the positions rate of change and helps to eliminate rapid fluctuations leading to overshoot

SimulationsInterface Matlab and STK

Orbital Mechanics vs PID ControlHohmann Transfer is useful for direct controlPID is useful for indirect control

Multiple simulations ranImpulsive burnsFinite burns

Questions?We would like to thank:Josh Johnson, Chris ChurchDr. Ron Fevig, Dr. William SemkeNorth Dakota Space Grant ConsortiumUND Seed/Planning Grant for Collaborative Research, Proposal Entitled, The Development of Predictive Control for Autonomous SystemsNSF Grant #EPS-081442