Optimal control for elliptic orbital rendezvous based on line-of-sight dynamic model

Optimal control methods for autonomous rendezvous on theelliptical orbit were discussed in line-of-sight(LOS) coordinate frame. Forthe rendezvous courses with constrained proximity aspects, an LOS dynamicmodel with respect to LOS measurement information was adopted so that LOSangle could be controlled directly. Then the rendezvous problem wasformulated as a nonlinear optimal control problem. The State-DependentRiccati Equation(SDRE) controller and \theta-D controller were derivedrespectively. Also an SDRE approach with the control thrust along the axisof Local Vertical / Local Horizontal(LVLH) frame was discussed for theavailability of control thrust. Numerical simulations demonstrated thefeasibility of the control strategies in constrained-aspect rendezvousmissions. The \theta-D controller got a higher computational efficiencyand lower control accuracy comparing with the SDRE controller. Moreover, theSDRE controller also could be achieved while the control thrust fixed withthe LVLH axis.