Autonomous robotic assembly by mobile field robots has seen significant advances in recent decades, yet practicality remains elusive. Identified challenges include better use of state estimation to and reasoning with uncertainty, spreading out tasks to specialized robots, and implementing representative joining methods. This paper proposes replacing 1) self-correcting mechanical linkages with generalized joints for improved applicability, 2) assembly serial manipulators with parallel manipulators for higher precision and stability, and 3) all-in-one robots with a heterogeneous team of specialized robots for agent simplicity. This paper then describes a general assembly algorithm utilizing state estimation. Finally, these concepts are tested in the context of solar array assembly, requiring a team of robots to assemble, bond, and deploy a set of solar panel mockups to a backbone truss to an accuracy not built into the parts. This paper presents the results of these tests.1 E. E. Komendera is with the Structural Mechanics and Concepts Branch,

This article provides a survey overview of the techniques, mechanisms, algorithms, and test and validation strategies required for the design of robotic grappling vehicles intended to approach and grapple free-flying client satellites. We concentrate on using a robotic arm to grapple a free-floating spacecraft, as distinct from spacecraft docking and berthing, where two spacecraft directly mate with each other. Robotic grappling of client spacecraft is a deceptively complex problem: It entails designing a robotic system that functions robustly in the visually stark, thermally extreme orbital environment, operating near massive and extremely expensive yet fragile client hardware, using relatively slow flight computers with limited and laggy communications. Spaceflight robotic systems are challenging to test and validate prior to deployment and extremely expensive to launch, which significantly limits opportunities to experiment with new techniques. These factors make the design and operation of orbital robotic systems significantly different from those of their terrestrial counterparts, and as a result, only a relative handful of systems have been demonstrated on orbit. Nevertheless, there is increasing interest in on-orbit robotic servicing and assembly missions, and grappling is the core requirement for these systems. Although existing systems such as the Space Station Remote Manipulator System have demonstrated extremely reliable operation, upcoming missions will attempt to expand the types of spacecraft that can be safely and dependably grappled and berthed. Expected final online publication date for the Annual Review of Control, Robotics, and Autonomous Systems, Volume 5 is May 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

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Research into controlling how robotic manipulation of materials can impart stresses into the system is a novel realm. Great robustness is needed to handle a variety of autonomous behaviors for the uncertainty of reaction from materials of different properties ranging from lightweight gossamer to stiffer truss structures. Currently robotic manipulation for space applications is done on a very case by case basis but in-space assembly (ISA) and servicing applications introduce a large number of possible uncertainties and anomalies that would be a departure from regular operations.My mechatronics thesis project focused on the development a Soft Stewart Platform (SSP) robot with precise 6 Degrees of Freedom (DOF) position control. A platform such as this could provide high precision with compliance to handle a diversity of material strengths, from stiff heterogenous structures to soft goods. The SSP concept is comprised of six Soft Linear Actuators (SLAs) with precision length control. An additional benefit of a SSP versus the conventional hard Stewart platform is the ability to store the robot in a compact state that is shorter than half the full actuator length, the limit for conventional electric linear actuators.The main application selected for this SSP concept was as an end effector to robotically manipulate gossamer structures and mitigate the impartment of stress and conduct specified testing on space telescope sunshields for how this manipulation could benefit deployment and handle servicing of anomaly cases. Overall, my research would provide benefits to NASA missions such as deploying, or recovering from failed deployment, of space telescope sunshields critical for astrophysics science such as exoplanet observations.