A range of space missions -- such as in-space inspection, diagnosis, assembly and situational awareness -- would be enhanced or enabled by the ability to maneuver an extremely small spacecraft in close proximity to other spacecraft.  However, the extremely small size of such spacecraft brings a strong sense of operational constraints in terms of available sensors, 6DOF actuation, and the need for collision avoidance.  Similarly, conventional control methods do not perform well in this regime due to the limitations of available thruster designs.

We have identified two methods to resolve this problem.  First, we have created a potential-function-based control approach to robustly manage the thruster limitations.  This method has the added benefit of allowing us to create complex motion behaviors from simple primitives. For the sensing problem, we estimate the total system state using an image-based navigation system augmented by rate gyros.

In this seminar, we will outline the scope of the problem, identify the key constraints, and then present the potential function control and image-based navigation methods.  Simulator results and, where possible, hardware-in-the-loop experiments will be discussed.