To develop our project, we loosely followed a design process for mechanical engineering designs from the University of Waterloo: 

Identify the need 

1. Define the problem 
2. Create a simple statement, stating the objectives clearly: “Design a mechanism to facilitate in-space assembly and docking” 
3. Determine a unit of analysis : Since we do not have the ability to test our model, we incorporated this aspect into part 2. 

Research other solutions: this is a list of the resources we looked at. Please see the references for links 

1. NASA’s On-Orbit Assembly and Manufacturing Concept: https://www.youtube.com/watch?v=xP4_Q7iIlb0&ab_channel=NASALangleyResearchCenter  
2. In-orbit Assembly Mission for the Space Solar Power Station (Paper) : https://doi.org/10.1016/j.actaastro.2016.08.019 
3. Tendon-Actuated Lightweight In-Space Manipulator (TALISMAN) 
4. ON-ORBIT ASSEMBLY OF SPACE ASSETS: A PATH TO AFFORDABLE AND ADAPTABLE SPACE INFRASTRUCTURE (PDF) : https://aerospace.org/sites/default/files/2018-05/OnOrbitAssembly_0.pdf  
5. Archinaut : https://www.popularmechanics.com/space/satellites/a26428/archinaut-made-in-space/   
6. https://madeinspace.us/capabilities-and-technology/archinaut/ 
7. Commercial Infrastructure for Robotic Assembly and Services (CIRAS) 
8. DEXTRE 

What are the shortfalls of existing solutions? 

1. NASA’s solution is not versatile; it is not immediately clear how large objects may be constructed. 
2. In-orbit Assembly Mission for the Space Solar Power Station employs free flying robots that refuel using solar panels delivered in the payload. This is a specialized solution. As such, end-effectors for robotic arms are already known. This is not versatile when developing a scalable solution. 
3. TALISMAN must be fixed in a location according to its implementation in NASA’s OSAM. This would make the construction of space objects a more difficult maneuver 
4. We feel that CIRAS’ role in the OSAM model does not fully realize the potential of smaller-scale automated in-space construction. 
5. Archinaut’s 3d printing solution is innovative, however, with only a scanner, printing and grabbing end-effector, we feel there is too little diversity. 
6. DEXTRE is a versatile robot that employs two modular arms. Since it is almost completely autonomous however, it is extremely large and space inefficient. 

What are the benefits of solving the problem? 

1. With modular structure design and assembly, the cost is spread out over time, as components can be delivered in individual payloads 
2. One would be able to construct objects which may not be possible under the influence of the earth’s gravitation field at Earth’s surface. 
3. Objects not able to be launched on earth due to size and weight constraints may be built and deployed in space. 
4. Access to an in-orbit station allows for easy docking for repairs, additions 
5. The versatility allows for the construction of smaller and larger objects using a single system 

Define the constraints to the problem: 

1. Constraints and Criteria 
2. Weight/fuel cost  /15   
3. Cost       /20  
4. Power Consumption    /20   
5. Modularity – the ability to assemble AND take apart    /20   
6. Versatility    /10  
7. Durability    /15   
8. *Weights were assigned to each criterion, together totalling 100. This process was done qualitatively. It is used to judge different design concepts.  

Brainstorm ideas to solve the problem (Ideation) 

1. The first idea that was conceived consisted of a 3-axis design, akin to a 3d printer. We found that maneuvering around the object to reach certain angles was inefficient. The design was also limited to the initial size constraints of the “box.” 
2. The second idea was two beams along a circular beam. We thought it was also, not scalable, and might in fact use more energy because of the three arms attached to the inner ring. 
3. The third idea was a gyroscope design of sorts. It attempts to simplify the problem of getting reaching angle on the object. With further thought, however, we realized that the size of the smallest ring was a serious limitation. 

Design selection: Select the top few criteria, (~5), assign and normalize weights 

1. The top design (design ii) achieved a score of 59 out of 100.  
2. Note that this is only the score for the initial design, we iterated and improved on the design throughout the development process. 
3. Mechanical Design 
4. Preliminary sketch 
5. Please see the PowerPoint presentation for the initial sketch 
6. *A problem we encountered while iterating our design was how the radius of the outer circle would increase. We designed multiple folding/hinge mechanisms and eventually settled on the foldable block and rail design. This allowed for blocks to be slotted into the circle easily, increasing the circle’s radius as its perimeter increases. The blocks were also designed to be foldable for easy storage if the radius of the circle needed to decrease.  

Re-sketch with manufacturing and joining processes in mind 

1. Since we were not focussing on choosing specific parts, we instead decided which existing robots to implement on our design: 
2. A smaller version of DEXTRE, which stores modular end-effectors inside the containing ring 
3. CIRAS is used to manufacture modular blocks, increasing the radius of the ring 

CAD model 

1. Please see the PowerPoint presentation for a screenshot of the orthographic projection of both the docking station and the modular blocks to be built by CIRAS 

Ensure objects are in the right place and have the appropriate size relative to each other (but no specified units) 

1. The dimensions of the modular blocks built by CIRAS were changed because the team felt the monorail segment was too small. 
2. A secondary ring was added in order to decrease construction time, as well as aid in assembly and disassembly. 

Re-build CAD model 

Describe any optimization strategy used 

1. We optimized our design as we sketched out initial designs. Optimization also took place in the CAD stage.  

Estimate performance 

1. We feel that since the docking station is completely modular, it can support extremely large designs, limited only by the strength and rigidity of the design of sub-components

Reflect on better designs  

1. Since structural integrity is of concern in large constructions, it follows that the docking station itself should be modular. This functionality allows many docking stations to join together in space, should there be a need to work on extremely large projects. Furthermore, these docking stations may detach easily and function independent of another docking station. Note that this does not change the decided-upon design of the docking station 

Prototype 

1. A Lego construction of an early design prototype was created. Please see the PowerPoint presentation. 

We referenced NASA’s OSAM design and the tools employed in that design in order to create our solution. These tools/robots were DEXTRE and CIRAS. 

Presentation.pptx

NASA’s On-Orbit Assembly and Manufacturing Concept 

1. https://www.youtube.com/watch?v=xP4_Q7iIlb0&ab_channel=NASALangleyResearchCenter  

In-orbit Assembly Mission for the Space Solar Power Station (Paper) 

1. https://doi.org/10.1016/j.actaastro.2016.08.019 

Tendon-Actuated Lightweight In-Space Manipulator (TALISMAN) 

ON-ORBIT ASSEMBLY OF SPACE ASSETS: A PATH TO AFFORDABLE AND ADAPTABLE SPACE INFRASTRUCTURE (PDF) 

1. https://aerospace.org/sites/default/files/2018-05/OnOrbitAssembly_0.pdf  

Archinaut 

1. https://www.popularmechanics.com/space/satellites/a26428/archinaut-made-in-space/   
2. https://madeinspace.us/capabilities-and-technology/archinaut/ 

DEXTRE 

1. https://www.asc-csa.gc.ca/eng/iss/dextre/default.asp