A Control Framework for CUBESAT Rendezvous and Proximity Operations using Electric Propulsion
Bo-Chuan Lin, Chun-Wei Kong, Simone Semeraro, Jay W. McMahon
TL;DR
The paper addresses rendezvous and proximity operations for two CubeSats in low Earth orbit when only a single body-fixed resistojet is available and real-time relative-state access is limited. It introduces a modular control framework based on four maneuver blocks that steer the chaser’s mean orbital elements toward a designed safety ellipse, using Hill's relative-motion model and mean-element updates derived from GNSS data. Key contributions include the practical decomposition of RPO into four thrust-based blocks, a safety-ellipse-centric control strategy compatible with power and sensing constraints, and a STK-based demonstration achieving a final safety ellipse of $14$ km $\times$ $27$ km $\times$ $8$ km with $ΔV=29.4$ m/s over a $41$-day maneuver. This work demonstrates the feasibility of low-thrust, indirect-information RPO for nanosatellite pairs and informs future autonomous relative navigation and control under limited state updates.
Abstract
A control framework is presented to solve the rendezvous and proximity operations (RPO) problem of the EP-Gemini mission. In this mission, a CubeSat chaser is controlled to approach and circumnavigate the other uncooperative CubeSat target. Such a problem is challenging because the chaser operates on a single electric propulsion thruster, for which coupling between attitude control and thrust vector, and charging of the electric propulsion system must be taken into consideration. In addition, the access to relative states in real time is not achievable due to the onboard hardware constraints of the two CubeSats. The developed control framework addresses these limitations by applying four modularized maneuver blocks to correct the chaser's mean orbit elements in sequence. The control framework is based on a relative motion called safety ellipse to ensure a low collision risk. The complete EP-Gemini mission is demonstrated by the implementation of the proposed control framework in a numerical simulation that includes high order perturbations for low Earth orbit. The simulation result shows that a safety ellipse is established after a 41-day RPO maneuver, which consumes 44$\%$ of the total fuel in terms of $ΔV$. The resulting 3-dimensional safety ellipse circumnavigates the target with an approximate dimension of 14 km $\times$ 27 km $\times$ 8 km.