Local Robotic Assembly of Large Spacecraft Structures

Apollo 11 Postdoctoral Fellowships at Purdue - Proposal

This collaborative proposal, led by Dr. Kawai Kwok (AAE) and Dr. Yu She (IE), aims to establish the foundational materials joining and robotic manipulation technologies to enable local and on-demand assembly and reconfiguration of composite aerospace structures. Delivering spacecraft and aircraft structures to their sites of operation is a requisite for long-journey space and defense expeditions. From the Earth to the Geostationary Orbit is a 36,000 km supply line and continuously transporting large and delicate spacecraft to orbit as integral units is faced with payload space availability and launch survival challenges. Navy vessels encounter similar difficulties with storing and launching aircraft on decks in remote territories. The ability to locally assemble and disassemble primary structures from building-block elements on site will lower the logistical footprint and vulnerability of the supply chain.

​Current lightweight spacecraft are constructed from thermoset composites where available assembly methods involve significant surface preparation or structural modification at the joining locations. Thermoplastic composites, on the other hand, are readily welded by combined thermal and mechanical actions and offer an attractive route for automation. Robotic welding of thermoplastic composites is being rapidly developed today for aircraft construction, but without consideration of the mass, volume and power constraints associated with in-space and remote operations. To make assembly of primary structures viable in highly constrained environments, the materials and equipment involved in the entire operation must be minimized. On the materials joining front, the PI (Dr. Kwok) is developing a resistance welding method using embedded carbon nanotube films, which serve as both the heater element and the structural  reinforcement, minimizing the mass by leverage material multi-functionality. Robotic manipulation is the other critical component in the assembly process that has yet to be developed. This fellowship will support a postdoctoral scholar to develop robotic systems for assembling and disassembling large truss structures made of thermoplastic composite elements in space environments.

Research Goals

  1. Design of mechanical robotic arms for gripping, positioning, orienting, and squeezing. The robotic arms will be able to manipulate structural elements without damage and to apply sufficient mechanical pressure during welding.
  2. Development of a sensory perception scheme for the robotic system. The integrated sensor will be enable tactile feedback and reactive control when manipulating structural elements.
  3. Development of a gravity compensation testbed for simulating robotic operations in microgravity condition. The testbed will allow probing of gravitational effects on the various degrees of freedom of the robotic system.

Expected Deliverables

  1. Proof-of-Concept Robot Prototype: A robotic system with sensing and manipulation capabilities to demonstrate assembly of a composite truss and prove the proposed concept.
  2. Gravity Compensation Test Platform: A generic experimental apparatus for compensating gravitational effects while preserving the kinematics of the robots.
  3. Funding Proposal: A funding proposal to the Office of Naval Research based on the developed and demonstrated hardware.
  4. The postdoctoral fellow is expected to publish journal articles, conference papers, and apply for patents when suitable.

Principal Investigators

Associate Professor Kawai Kwok
School of Aeronautics and Astronautics, Purdue University

Assistant Professor Yu She
Edwardson School of Industrial Engineering, Purdue University

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