Introduction
We are a team of six final-year Engineering students from the University of Southampton, currently working on our Master’s group project. Our project aims to address the growing issue of space debris in Earth’s orbit. We are developing the Scalable, Origami-inspired, Active Recovery Gripper (SOAR-Gripper) as a potential solution.
The Debris Problem
The increasing volume of debris significantly limits the use of orbital resources and endangers the safety of operational spacecraft. High-profile incidents, such as the collision between Iridium 33 and Cosmos 2251, have further emphasised the urgency of addressing this issue. Simulations run by the European Space Agency and NASA show that even in a scenario where no additional objects are introduced into space, the number of debris objects would continue to grow due to fragmentation from existing debris, collisions, and other cascading effects. This highlights the need for adaptable remediation methods, such as Active Debris Removal (ADR).
Current research in the field of ADR focuses on developing reliable and cost-effective systems to address the growing threat posed by debris. The SOAR-Gripper aims to contribute to these efforts by providing a scalable and efficient solution for capturing and removing space debris.
Our Solution
Origami-inspired engineering, particularly its application in soft robotics, is gaining traction as a potential solution due to its adaptability and efficiency. Given that the dimensions of debris is often unknown prior to launch of an ADR mission, our goal is to design a gripper that utilises the unique benefits of origami-inspired soft robotics. This will allow the gripper to adapt to various sizes and shapes of debris.
Actuation of Gripper
We have chosen to use shape memory alloys (SMAs) to actuate the gripper and enable it to switch between its open and closed positions. SMAs can ‘remember’ a shape and return to it when heated to their activation temperature. To control the heating process, we aim to design a circuit that activates the SMAs when a piece of debris approaches.
Electronic Circuit
A crucial aspect of our project is the design of the electronic circuit, which will ensure the gripper’s shape-changing capabilities are fully utilisable, ensuring that each cell is fully controllable.
The key component that gives us full control of the gripper is the MOSFET. MOSFETs are a type of transistor that can regulate the flow of current between two terminals by applying a voltage to a third terminal. With their high efficiency and fast switching speeds, MOSFETs allow us to control the gripper’s actuation smoothly and efficiently.
SMAs themselves have negligible resistance, so to ensure proper operation of the circuit, we are using 1.5Ω wire wound chassis mount resistors. These resistors are critical for ensuring a controlled heating process. Wire wound resistors are designed to dissipate heat effectively, preventing circuit components from overheating.
Results and Impact
We have successfully designed the circuit, and the next step is integrating it into our gripper model. We are grateful to have received funding from RS for our project, which has allowed us to purchase high-quality SMA with an activation temperature that suits our design, as well as other essential electronic components. This support ensures the development of a safe and efficient circuit.
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