Fault Tolerant Algorithms for In-orbit Manufacture

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There is a large drive for in-orbit manufacturing to help realise ambitious large-scale missions to the moon and beyond, and for use in space-based services such as telecommunications and Earth observation. However, there are several issues within the field related to the detection of failures within the manufacturing process and the autonomous assembly of these structures directly on orbit.Investigating methods for the failure detection and recovery of objects in manufacture within a space environment is the prime focus for this project. Effort will be made to determine if the use of physical sensors, machine vision, and other inputs can correctly detect the different failure modes of a 3D printed object, such as delamination and surface/structural defects. This would require simulation and comparison of both the dynamics of the printer throughout the printing process, and the printed object itself at any stage for visual comparison. This initial body of work will inform the rest of the project. It is expected that machine vision will be needed to detect non-printer related faults. There is only limited research available within this area. It is envisioned that a combination of physical sensors on the printer and the machine vision algorithms will be able to detect faults and defects within the printed objects in real-time.Once a robust method for detecting faults has been developed, methods to evaluate and recover the printing object can be investigated; such as the removal of stray material via robotic arm, or addition of material in the failure region. Again, there is limited work available in this area and there are multiple solutions that can be envisioned. Initial efforts will be based on the severity of the fault. For example, small imperfections, such as warping, may be recoverable in real-time with the addition of single layers to compensate. Algorithms for deciding on the severity of the error and how the error can be recovered will be a significant output of this work.Recovery of an object requires significant research into simulation techniques to determine which, if any, methods will allow a print to continue. Optimisation algorithms can be used to establish what the optimal method of recovery should be, while, for more serious defects, the use of a robotic manipulators could remove affected regions of an object for reprinting.Since target application is intended to support in-orbit manufacturing, the extreme space environment will provide constraints upon the design solutions. It is vital that the print success rate is as high as possible given the nature of the mission where manual intervention is impractical and the cost to launch feedstock is so great. This is even more so in the case of large-scale structural manufacture.