Sequential Control of Electromagnets for CubeSat Docking Attitude Alignment

Autonomous docking is an essential component of spacecraft innovation. It allows spacecraft to link together, allowing in-space assembly (constructing larger, more sophisticated space structures using building pieces) and on-orbit servicing (transferring goods and services in space). Non-contact docking is a concept in which two or more spaceships are secured together but do not make physical touch. This makes it safer to attach to another spacecraft because if there are any faults during the rendezvous and proximity operations phase, the chances of collision and subsequent failure are less. As a result, there are fewer chances of contact and leakage problems. For bigger “mother” spacecraft, smaller non-contact docking spacecraft can be utilized for formation flying, surveillance, security, and defect detection. One of the safest approaches to this problem is electromagnetic levitation. A magnetic field will keep the CubeSat in place while allowing it to “hover” around the mothership. This study describes the concept and technology required for a soft rotational lock between the two spacecraft. Active illumination signals such as flashing LEDs and photodetectors might be used to identify the docking spacecraft. Then, they will approach each other and align so that both magnets are in close proximity. We suggest employing electromagnets for alignment and non-contact docking once the two spacecraft are near enough to one another. A rotational lock between the two spacecraft is accomplished by an algorithm that turns on a ring of electromagnets sequentially in the two spacecraft, causing a differential in attractive forces to provide a roll and then an orientation lock. We then compare this method to other methods, such as incorporating ratiometric sensors, which will raise the voltage in the electromagnet as the magnetic field rises, with negative feedback to assist it in stabilizing. In addition, the system will include concentric anti-polar magnets that resist and attract each other to maintain a steady posture. Finally, we propose verification and validation methods for the system and provide a working prototype as a proof of concept.