Sensor Craft Control Using Drone Craft with Coulomb Propulsion System
The Coulomb propulsion system has no exhaust plume impingement problem with neighboring spacecraft and does not contaminate their sensors because it requires essentially no propellant. It is suitable to close formation control on the order of dozens of meters. The Coulomb forces are internal forces of the formation and they influence all charged spacecraft at the same time. Highly nonlinear and strongly coupled equations of motion of Coulomb formation makes creating a Coulomb control method a challenging task. Instead of positioning all spacecraft, this study investigates having a sensor craft be sequentially controlled using dedicated drone craft. At least three drone craft are required to control a general sensor craft position in the inertial space. However, the singularity of a drone plane occurs when a sensor craft moves across the drone plane. A bang-bang control method with a singularity check can avoid this problem but may lose formation control as the relative distances grow bounded. A bang-coast-bang control method utilizing a reference trajectory profile and drone rest control is introduced to increase the control effectiveness. The spacecraft are assumed to be floating freely in inertial space, an approximation of environments found while underway to other solar system bodies. Numerical simulation results show the feasibility of sensor craft control using Coulomb forces.