Safety-critical autonomous spacecraft proximity operations via potential function guidance

This paper details the development and evaluation of potential function guidance for path constrained proximity maneuvers of spacecraft at the International Space Station. The method requires the definition of a scalar potential function that represents the constrained operating environment. The potential function has a minimum at the desired goal position and has regions of high potential at path constraints. The spacecraft controls are chosen such that the rate of descent of the potential function is rendered negative definite. This ensures that the spacecraft state converges to the desired goal point without violating path constraints, such as keep-out zones and approach corridors. It is demonstrated that complex path planning with both V-bar and R-bar approaches can be achieved using a minimum of computational effort. Furthermore, since the method may be mathematically validated it is attractive for safety critical applications such as ATV and HTV proximity operations.