Final Design

The deliverable for the ISAM challenge was a CAD animation demonstrating a three-step process within the proposed system during use.

For our proposed autonomously assembling rail system, the three steps that were highlighted can be seen below:

In addition to these animations, key components of the proposed system were conceptually fleshed out, and can be seen below along with some key highlighted features. 

Rail Unit Design

• T-slot creates mechanical connection to drivetrain, which is necessary in the microgravity to keep the drivetrains in contact with the rail

• 90° symmetry allows four different orientations of connection, reducing manipulation required in during assembly and disassembly

• Simple geometry allows multiple manufacturing methods and materials

• Prototyped using 50.8 x 50.8 x 127 mm units; dimensions can change based on mission requirements

Connection Mechanism

• Square profile ensures beams orient correctly

• Compliant clip requires no extra components for assembly which can be performed by a single actuator

• Female connector negative space makes beam hollow, reducing 3D printing times and improving material efficiency

• Steep angle on backside of connector: higher force required to disconnect than connect

Curved Rail Units

• 90° and 45° turn rail units were designed and prototyped to allow drivetrains to access all 3D space around host satellite

• Curvature analysis was conducted utilizing the prototyped drivetrain's geometry, and it was found that a 90° turn would be impractical to manufacture and store within payload dimensions

• The 45° turn unit allows more flexibility when building rail paths to a location, making it more attractive

T-Slider

• Elliptical shape was selected to allow for the slider to turn corners and choose a path on a split rail by rotating about its center axis

  • Experiments showed that an elliptical T-slider got jammed in the T-slot less than other geometries

• Hinge mechanism allows for turning on the inside and outside faces of the rail, allowing access to all 3D space

• The implemented system will include bearings on T-slider faces to reduce friction

Drivetrain

• Left drivetrain was prototyped and tested over the course of the project and was determined to be a viable option for the system

• Right drivetrain is a monorail concept that could also work well for the system

• Implemented drivetrain would be custom-built for the torque, speed, and power requirements of each mission

• Drivetrains are an area that is thoroughly understood, so team energy was spent on details of other aspects of the system

Rail Unit Storage System

• Spring-loaded similar to a firearm magazine allows rail units to be pulled out for retrieval

• Restocking requires the reverse operation, pushing rail unit back into opening of storage magazine

• Only one beam accessible at once

• All rails retrieved from same position at opening of magazine makes retrieval reliable

• Proof-of-concept magazines hold 5 rail units, allowing for a total storage of 25 rail units